Dissertationen: „Geotechnical methods“

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Sleiman, Maya. „2D Modelling of GeosyntheticallyReinforced Piled Embankments : Calibration Methods in PLAXIS 2D & Review of AnalyticalGuidelines“. Thesis, KTH, Jord- och bergmekanik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-291424.

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This thesis focuses on the 2D modelling of Geosyntheticaly Reinforced Piled Embankments (GRPE) in PLAXIS 2D. In doing so, it explores two main aspects: 1) the calibration of Interface Stiffness Factors (ISFs) governing the soil-pile interaction of Embedded BeamRow (EBR) elements in PLAXIS 2D, and 2) the prospects and limitations of modelling geogrids (GR) in PLAXIS 2D when underlain by EBR elements; although several studies have validates the EBR element in modelling piles, none address the geogrid-EBR interaction and its implications on modelling GRPE systems. The thesis performs the calibration and validation processes using the full-scale GRPE structure ASIRI (Amélioration des Sols parInclusions Rigide) as documented in Briançon and Simon, 2012 and Nunez et al., 2013. Calibration of the EBR’s ISFs is done against 1) load-displacement curve of a test pile, 2)load-displacement of the structure’s monitored piles, and 3) differential soil-pile settlement. Model results for soil settlement, pile settlement, and pile load are then compared to reported values from the ASIRI site. Results show that the natural deviation between the structure and test pile’s load - displacement results in a wide range of possible calibration values for the ISFs, making calibration based on a test pile’s load-displacement curve an unpractical method. Even when such natural deviations were eliminated by calibrating the model against the structure’s reported values for pile load-displacement, model predictions for subsoil displacement were compromised. It is thus advisable to calibrate the EBR element with respect to soil settlement, pile settlement, and pile load rather than solely on a load-displacement curve as to avoid high divergences in soil-pile differential settlement. Modelling geogrids in GRPE systems, PLAXIS 2D underestimates GR strain due to its inability to simulate GR deflection: EBR elements are superimposed on top of a continuous soil mesh, thus allowing the embankment soil to settle through the EBR element. This unrealistically minimizes GR deflection, which underestimates GR strain when modelling GRPEs in PLAXIS 2D. In addition to validating the 2D modelling of GRPE systems, the thesis conducts a comparative literature review of GRPE design guidelines, focusing on the British BS8006 (2010), the German EBGEO (2011), and the Dutch CUR226 (2016). It then applies the latter two to the ASIRI full scale case study and compares results for predicted maximum GR strainand displacement to those from the PLAXIS 2D model and ASIRI measurements. The literature review shows that the geogrid load distribution is highly dependent on the state of subsoil support, where a uniform distribution is more appropriate for high subsoil support, and an inverse-triangular one more appropriate for low subsoil support. However, the analytical analysis of the ASIRI case shows that the triangular distribution, previously dismissed as unrealistic by the literature review, gives satisfactory results due to a combination of soil sliding and high subsoil support at the ASIRI site.
Examensarbetet utvärderar 2D modellering av bankpålning med geosyntetisk armering (Geosyntheticallt Reinforced Piled Embankments – GRPE) i PLAXIS 2D. Examensarbetet utforskar två huvudaspekter: 1) kalibrering av Interface Stiffness Factors (ISFs) som styrjord-påle samspelet av Embedded Beam Row (EBR) element i PLAXIS 2D, och 2) möjligheter och begränsningar vid modellering av geonät i PLAXIS 2D när de ligger över EBR element. Även om flera studier har validerat användningen av EBR element för modelleringenav pålning, har inga behandlat samspelet geonät-EBR samt dess implikationer på modelleringen av GRPE. I arbetet har kalibrerings- och valideringsprocesser genomförts genom att använda den fullskaliga GRPE strukturen ASIRI (Amélioration des Sols par Inclusions Rigide) som dokumenterats i Briançon och Simon(2012) samt Nunez et al. (2013). Kalibrering av EBR ISFshar utförts mot: 1) last/förskjutningssamband av testpålar, 2) last/förskjutningssambad av övervakade pålar i strukturen, och 3) jord-påle differenssättningen. Modellens resultat försättningar i jorden, deformation i pålarna och lasten i pålarna jämförs med mätningar från ASIRI. Resultaten visar att naturliga avvikelser mellan strukturens- och testpålens last/förskjutningssambad resulterar i ett brett spektrum av möjliga kalibreringsvärden för ISFs, som gör kalibrering mot testpålens last/förskjutningssambad opraktisk. Även vid justering för detta genom kalibrering mot strukturpålens last/förskjutningssambad minskade modellens noggrannhet för sättningar i jorden. Det är således lämpligt att kalibrera EBR element motsättningar i jorden, deformation i pålarna och lasten i pålarna i stället för bara last/förskjutningssambaden för att undvika hög divergens i differenssättningen jord-påle. Vid modellering av GRPE-geonät underskattar PLAXIS 2D töjningen i geonäten på grund av sin oförmåga att simulera geonätens utböjning. EBR element ligger över ett kontinuerligt beräkningsnät av jord (soil mesh) som tillåter bankfyllningen att sätta genom EBRelement. Detta förhindrar utböjningen i geonätet som resulterar i en underskattning av töjningen i nätet vid modellering av GRPE i PLAXIS 2D. Förutom validering av 2D modelleringen av GRPE strukturer utför examensarbetet en jämförande literaturstudie av GRPE dimensioneringsriktlinjer med fokus på Brittisk BS8006 (2010), Tysk EBGEO (2011), och Nederländsk CUR226 (2016). De två sista nämnda riktlinjerna tillämpas på ASIRI för att prognosticera maximum geonättöjning och utböjning. Beräkningsresultat jämförs med värden från PLAXIS 2D modellen och mätningar från ASIRI. Litteraturstudien visar att geonätens belastningsfördelning är beroende främst på stödet från den underliggande jorden. Likformig belastningsfördelningen är lämpligare för en hög stödnivå och en invers-triangulär belastningsfördelningen för en låg stödnivå. Dock visar den analytiska analysen av ASIRI strukturen att en triangulär belastningsfördelning, som ansågs vara orealistisk i litteraturstudien, ger tillfredsställande resultat. Det är på grund av kombinationen av ’jordensglidning’ och hög stödnivå från den underliggandejorden i ASIRI:s fall.

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Sleiman, Maya. „2D Modelling of Geosynthetically Reinforced Piled Embankments : Calibration Methods in PLAXIS 2D & Review of Analytical Guidelines“. Thesis, KTH, Jord- och bergmekanik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-291424.

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This thesis focuses on the 2D modelling of Geosyntheticaly Reinforced Piled Embankments (GRPE) in PLAXIS 2D. In doing so, it explores two main aspects: 1) the calibration of Interface Stiffness Factors (ISFs) governing the soil-pile interaction of Embedded BeamRow (EBR) elements in PLAXIS 2D, and 2) the prospects and limitations of modelling geogrids (GR) in PLAXIS 2D when underlain by EBR elements; although several studies have validates the EBR element in modelling piles, none address the geogrid-EBR interaction and its implications on modelling GRPE systems. The thesis performs the calibration and validation processes using the full-scale GRPE structure ASIRI (Amélioration des Sols parInclusions Rigide) as documented in Briançon and Simon, 2012 and Nunez et al., 2013. Calibration of the EBR’s ISFs is done against 1) load-displacement curve of a test pile, 2)load-displacement of the structure’s monitored piles, and 3) differential soil-pile settlement. Model results for soil settlement, pile settlement, and pile load are then compared to reported values from the ASIRI site. Results show that the natural deviation between the structure and test pile’s load - displacement results in a wide range of possible calibration values for the ISFs, making calibration based on a test pile’s load-displacement curve an unpractical method. Even when such natural deviations were eliminated by calibrating the model against the structure’s reported values for pile load-displacement, model predictions for subsoil displacement were compromised. It is thus advisable to calibrate the EBR element with respect to soil settlement, pile settlement, and pile load rather than solely on a load-displacement curve as to avoid high divergences in soil-pile differential settlement. Modelling geogrids in GRPE systems, PLAXIS 2D underestimates GR strain due to its inability to simulate GR deflection: EBR elements are superimposed on top of a continuous soil mesh, thus allowing the embankment soil to settle through the EBR element. This unrealistically minimizes GR deflection, which underestimates GR strain when modelling GRPEs in PLAXIS 2D. In addition to validating the 2D modelling of GRPE systems, the thesis conducts a comparative literature review of GRPE design guidelines, focusing on the British BS8006 (2010), the German EBGEO (2011), and the Dutch CUR226 (2016). It then applies the latter two to the ASIRI full scale case study and compares results for predicted maximum GR strainand displacement to those from the PLAXIS 2D model and ASIRI measurements. The literature review shows that the geogrid load distribution is highly dependent on the state of subsoil support, where a uniform distribution is more appropriate for high subsoil support, and an inverse-triangular one more appropriate for low subsoil support. However, the analytical analysis of the ASIRI case shows that the triangular distribution, previously dismissed as unrealistic by the literature review, gives satisfactory results due to a combination of soil sliding and high subsoil support at the ASIRI site.
Examensarbetet utvärderar 2D modellering av bankpålning med geosyntetisk armering (Geosyntheticallt Reinforced Piled Embankments – GRPE) i PLAXIS 2D. Examensarbetet utforskar två huvudaspekter: 1) kalibrering av Interface Stiffness Factors (ISFs) som styrjord-påle samspelet av Embedded Beam Row (EBR) element i PLAXIS 2D, och 2) möjligheter och begränsningar vid modellering av geonät i PLAXIS 2D när de ligger över EBR element. Även om flera studier har validerat användningen av EBR element för modelleringenav pålning, har inga behandlat samspelet geonät-EBR samt dess implikationer på modelleringen av GRPE. I arbetet har kalibrerings- och valideringsprocesser genomförts genom att använda den fullskaliga GRPE strukturen ASIRI (Amélioration des Sols par Inclusions Rigide) som dokumenterats i Briançon och Simon(2012) samt Nunez et al. (2013). Kalibrering av EBR ISFshar utförts mot: 1) last/förskjutningssamband av testpålar, 2) last/förskjutningssambad av övervakade pålar i strukturen, och 3) jord-påle differenssättningen. Modellens resultat försättningar i jorden, deformation i pålarna och lasten i pålarna jämförs med mätningar från ASIRI. Resultaten visar att naturliga avvikelser mellan strukturens- och testpålens last/förskjutningssambad resulterar i ett brett spektrum av möjliga kalibreringsvärden för ISFs, som gör kalibrering mot testpålens last/förskjutningssambad opraktisk. Även vid justering för detta genom kalibrering mot strukturpålens last/förskjutningssambad minskade modellens noggrannhet för sättningar i jorden. Det är således lämpligt att kalibrera EBR element motsättningar i jorden, deformation i pålarna och lasten i pålarna i stället för bara last/förskjutningssambaden för att undvika hög divergens i differenssättningen jord-påle. Vid modellering av GRPE-geonät underskattar PLAXIS 2D töjningen i geonäten på grund av sin oförmåga att simulera geonätens utböjning. EBR element ligger över ett kontinuerligt beräkningsnät av jord (soil mesh) som tillåter bankfyllningen att sätta genom EBRelement. Detta förhindrar utböjningen i geonätet som resulterar i en underskattning av töjningen i nätet vid modellering av GRPE i PLAXIS 2D. Förutom validering av 2D modelleringen av GRPE strukturer utför examensarbetet en jämförande literaturstudie av GRPE dimensioneringsriktlinjer med fokus på Brittisk BS8006 (2010), Tysk EBGEO (2011), och Nederländsk CUR226 (2016). De två sista nämnda riktlinjerna tillämpas på ASIRI för att prognosticera maximum geonättöjning och utböjning. Beräkningsresultat jämförs med värden från PLAXIS 2D modellen och mätningar från ASIRI. Litteraturstudien visar att geonätens belastningsfördelning är beroende främst på stödet från den underliggande jorden. Likformig belastningsfördelningen är lämpligare för en hög stödnivå och en invers-triangulär belastningsfördelningen för en låg stödnivå. Dock visar den analytiska analysen av ASIRI strukturen att en triangulär belastningsfördelning, som ansågs vara orealistisk i litteraturstudien, ger tillfredsställande resultat. Det är på grund av kombinationen av ’jordensglidning’ och hög stödnivå från den underliggandejorden i ASIRI:s fall.

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Bhamidipati, Raghava A. „Use Of Laboratory Geophysical And Geotechnical Investigation Methods To Characterize Gypsum Rich Soils“. UKnowledge, 2016. http://uknowledge.uky.edu/ce_etds/45.

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Gypsum rich soils are found in many parts of the world, particularly in arid and semi-arid regions. Most gypsum occurs in the form of evaporites, which are minerals that precipitate out of water due to a high rate of evaporation and a high mineral concentration. Gypsum rich soils make good foundation material under dry conditions but pose major engineering hazards when exposed to water. Gypsum acts as a weak cementing material and has a moderate solubility of about 2.5 g/liter. The dissolution of gypsum causes the soils to undergo unpredictable collapse settlement leading to severe structural damages. The damages incur heavy financial losses every year. The objective of this research was to use geophysical methods such as free-free resonant column testing and electrical resistivity testing to characterize gypsum rich soils based on the shear wave velocity and electrical resistivity values. The geophysical testing methods could provide quick, non-intrusive and cost-effective methodologies to screen sites known to contain gypsum deposits. Reconstituted specimens of ground gypsum and quartz sand were prepared in the laboratory with varying amounts of gypsum and tested. Additionally geotechnical tests such as direct shear strength tests and consolidation tests were conducted to estimate the shear strength parameters (drained friction angle and cohesion) and the collapse potential of the soils. The effect of gypsum content on the geophysical and geotechnical parameters of soil was of particular interest. It was found that gypsum content had an influence on the shear wave velocity but had minimal effect on electrical resistivity. The collapsibility and friction angle of the soil increased with increase in gypsum. The information derived from the geophysical and geotechnical tests was used to develop statistical design equations and correlations to estimate gypsum content and soil collapse potential.

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Holmström, Robin, und Dmytro Yakubov. „Evaluation of future trial embankments : A study of measurement methods to apply on Lampen test embankments, Kalix, Sweden“. Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-62824.

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At the Lampen site outside of Kalix, Sweden two embankments with heights 1,5m and 2m have been built to study and test the properties of sulfide soil that is located in the Gulf of Bothnia coastal areas. In this master thesis investigations have been done on what more could be done at the Lampen site today concerning new technics, measurements, observations and calculations etc. rather than building new embankments. Conclusions have been drawn from a total of 7 cases including Lampen what more could be done at the Lampen site. Verifications have also been done on the work made at the different cases. It was concluded that the work on all the different cases could be verified in some way against hand calculations or PLAXIS models beside the Murro test embankment site because this work had too little release data aterial given. Made verifications gave corresponding results to the described and measured ones in the real cases. Cases that have been looked at are: 􀀀 Murro test embankment (Karstunen et.al, 2005) 􀀀 Test embankment constructed to failure on soft marine clay in Malaysia (Brand, 1991) 􀀀 Test embankment on hydraulically placed PFA (Pulverized Fuel Ashes) in the United Kingdom (Cousens, et al., 2003) 􀀀 Trial Embankment on peat in Booneschans the Netherlands (Zwanenburg, et al., 2012) 􀀀 A case study on sulphide soil on road of E12 north link, Västerslätt, Umeå, Sweden (Törnqvist, 2013) 􀀀 Follow up and evaluation of settlements on the road 760 in Norrbotten, Sweden (Johansson, 2010) 􀀀 Test Embankments Lampen, Sweden (Andersson, 2012) From these cases it was concluded that more calculations in Plaxis 2D, Plaxis 3D and maybe Geosuite settlements software programs should be done at the Lampen site, both for long term and short term behavior and settlements as the only current model made is an Embacko V1.02 which is based on the work and results by Andersson (2012). Also verifications should be made by hand calculations on the models as this had not been done until today. Further disturbed samples should have been taken at the Lampen site as it have been done at the Murro site in Finland as this site is built on similar ground conditions with sulfide soil. Heavy equipment used at the site and as well the building of the embankments might have disturb or influenced the soil so the properties might have been changed. Also a couple of new measurement technics have been looked at for Lampen. The looked at technics are optics fibers, drones and ShapeAccelArray (SAA). ShapeAccelArray (SAA) devices could be installed at some different points on the site, down through the soil profile to give better readings on vibrations, accelerations, deformations and settlements. A drone could also be used during the snow free period to fly daily-predefined paths and make a 3D mapping of the geotechnical structures. And if the embankments would be built now again from the start it would be a good idea to install from the start a smart geotextile with polymer optical fibers (POF) totally covering the whole embankment size. This would give continues reading on deformations and displacements. But since the measurements and all other work at the Lampen site in the project went well and gave good results there is no need to do further changes.

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Santos, Rodríguez Cristian de. „Backanalysis methodology based on multiple optimization techniques for geotechnical problems“. Doctoral thesis, Universitat Politècnica de Catalunya, 2015. http://hdl.handle.net/10803/334179.

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Nowadays, thanks to the increase of computers capability to solve huge and complex problems, and also thanks to the endless effort of the geotechnical community to define better and more sophisticated constitutive models, the challenge to predict and simulate soil behavior has been eased. However, due to the increase in that sophistication, the number of parameters that define the problem has also increased. Moreover, frequently, some of those parameters do not have a real geotechnical meaning as they just come from mathematical expressions, which makes them difficult to identify. As a consequence, more effort has to be placed on parameters identification in order to fully define the problem. This thesis aims to provide a methodology to facilitate the identification of parameters of soil constitutive models by backanalysis. The best parameters are defines as those that minimize an objective function based on the differences between measurements and computed values. Different optimization techniques have been used in this study, from the most traditional ones, such as the gradient based methods, to the newest ones, such as adaptive genetic algorithms and hybrid methods. From this study, several recommendations have been put forward in order to take the most advantage of each type of optimization technique. Along with that, an extensive analysis has been carried out to determine the influence on soil parameters identification of what to measure, where to measure and when to measure in the context of tunneling. The Finite Element code Plaxis has been used as a tool for the direct analysis. A FORTRAN code has been developed to automate the entire backanalysis procedure. The Hardening Soil Model (HSM) has been adopted to simulate the soil behavior. Several soil parameters of the HSM implemented in Plaxis, such as E_50^ref, E_ur^ref, c and f, have been identified for different geotechnical scenarios. First, a synthetic tunnel case study has been used to analyze all the different approaches that have been proposed in this thesis. Then, two complex real cases of a tunnel construction (Barcelona Metro Line 9) and a large excavation (Girona High-Speed Railway Station) have been presented to illustrate the potential of the methodology. Special focus on the influence of construction procedures and instruments error structure has been placed for the tunnel backanalysis, whereas in the station backanalysis, more effort has been devoted to the potential of the concept of adaptive design by backanalysis. Moreover, another real case, involving a less conventional geotechnical problem, such as Mars surface exploratory rovers, has been also presented to test the backanalysis methodology and the reliability of the Wong & Reece wheel-terrain model; widely adopted by the terramechanics community, but nonetheless, still not fully accepted when analyzing lightweight rovers as the ones that have been used in recent Mars exploratory missions.
Actualmente, gracias al aumento de la capacidad de los ordenadores para resolver problemas grandes y complejos, y gracias también al gran esfuerzo de la comunidad geotécnica de definir mejores y más sofisticados modelos constitutivos, se ha abordado el reto de predecir y simular el comportamiento del terreno. Sin embargo, debido al aumento de esa sofisticación, también ha aumentado el número de parámetros que definen el problema. Además, frecuentemente, muchos de esos parámetros no tienen un sentido geotécnico real dado que vienen directamente de expresiones puramente matemáticas, lo cual dificulta su identificación. Como consecuencia, es necesario un mayor esfuerzo en la identificación de los parámetros para poder definir apropiadamente el problema. Esta tesis pretende proporcionar una metodología que facilite la identificación mediante el análisis inverso de los parámetros de modelos constitutivos del terreno. Los mejores parámetros se definen como aquellos que minimizan una función objetivo basada en la diferencia entre medidas y valores calculados. Diferentes técnicas de optimización han sido utilizadas en este estudio, desde las más tradicionales, como los métodos basados en el gradiente, hasta las más modernas, como los algoritmos genéticos adaptativos y los métodos híbridos. De este estudio, se han extraído varias recomendaciones para sacar el mayor provecho de cada una de las técnicas de optimización. Además, se ha llevado a cabo un análisis extensivo para determinar la influencia sobre qué medir, dónde medir y cuándo medir en el contexto de la excavación de un túnel. El código de Elementos Finitos Plaxis ha sido utilizado como herramienta de cálculo del problema directo. El desarrollo de un código FORTRAN ha sido necesario para automatizar todo el procedimiento de Análisis Inverso. El modelo constitutivo de Hardening Soil ha sido adoptado para simular el comportamiento del terreno. Varios parámetros del modelo constitutivo de Hardening implementado en Plaxis, como E_50^ref, E_ur^ref, c y f, han sido identificados para diferentes escenarios geotécnicos. Primero, se ha utilizado un caso sintético de un túnel donde se han analizado todas las distintas técnicas que han sido propuestas en esta tesis. Después, dos casos reales complejos de una construcción de un túnel (Línea 9 del Metro de Barcelona) y una gran excavación (Estación de Girona del Tren de Alta Velocidad) se han presentado para ilustrar el potencial de la metodología. Un enfoque especial en la influencia del procedimiento constructivo y la estructura del error de las medidas se le ha dado al análisis inverso del túnel, mientras que en el análisis inverso de la estación el esfuerzo se ha centrado más en el concepto del diseño adaptativo mediante el análisis inverso. Además, otro caso real, algo menos convencional en términos geotécnicos, como es la exploración de la superficie de Marte mediante robots, ha sido presentado para examinar la metodología y la fiabilidad del modelo de interacción suelo-rueda de Wong y Reece; extensamente adoptado por la comunidad que trabajo en Terramecánica, pero aún no totalmente aceptada para robots ligeros como los que se han utilizado recientemente en las misiones de exploración de Marte.

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Salehian, Ali. „PREDICTING THE DYNAMIC BEHAVIOR OF COAL MINE TAILINGS USING STATE-OF-PRACTICE GEOTECHNICAL FIELD METHODS“. UKnowledge, 2013. http://uknowledge.uky.edu/ce_etds/9.

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This study is focused on developing a method to predict the dynamic behavior of mine tailings dams under earthquake loading. Tailings dams are a by-product of coal mining and processing activities. Mine tailings impoundments are prone to instability and failure under seismic loading as a result of the mechanical behavior of the tailings. Due to the existence of potential seismic sources in close proximity to the coal mining regions in the United States, it is necessary to assess the post-earthquake stability of these tailings dams. To develop the aforementioned methodology, 34 cyclic triaxial tests along with vane shear tests were performed on undisturbed mine tailings specimens from two impoundments in Kentucky. Therefore, the liquefaction resistance and the residual shear strength of the specimens were measured. The laboratory cyclic strength curves for the coal mine specimens were produced, and the relationship between plasticity, density, cyclic stress ratio, and number of cycles to liquefaction were identified. The samples from the Big Branch impoundment were generally loose samples, while the Abner Fork specimens were dense samples, older and slightly cemented. The data suggest that the number of loading cycles required to initiate liquefaction in mine tailings, NL, decreases with increasing CSR and with decreasing density. This trend is similar to what is typically observed in soil. For a number of selected specimens, using the results of a series of small-strain cyclic triaxial tests, the shear modulus reduction curves and damping ratio plots were created. The data obtained from laboratory experiments were correlated to the previously recorded geotechnical field data from the two impoundments. The field parameters including the SPT blow counts (N1)60, corrected CPT cone tip resistance (qt), and shear wave velocity (vs), were correlated to the laboratory measured cyclic resistance ratio (CRR). The results indicate that in general, the higher the (N1)60 and the tip resistance (qt), the higher the CSR was. Ultimately, practitioners will be able to use these correlations along with common state-of-practice geotechnical field methods to predict cyclic resistance in fine tailings to assess the liquefaction potential and post-earthquake stability of the impoundment structures.

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Katsigiannis, Georgios. „Modern geotechnical codes of practice and new design challenges using numerical methods for supported excavations“. Thesis, University College London (University of London), 2017. http://discovery.ucl.ac.uk/10037673/.

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Eurocode 7 (EC7), which is the geotechnical engineering design standard in Europe, introduces the concept of partial safety factors and distinguishes between Serviceability Limit State (SLS) and Ultimate Limit State (ULS). While EC7 allows the use of Finite Element Methods (FEM) for ULS, there is limited guidance in a number of issues. The thesis focuses on a number of constitutive models of increasing complexity and both the characteristic and design values of the model parameters are derived for the London Clay and a soft Marine clay. The challenges associated with factoring the undrained shear strength when using total and effective stress parameters are discussed. The use of FEM for ULS design of supported excavations, is highlighted using simple excavation examples and two deep excavation case histories; the Moorgate Crossrail Station and the Exhibition Road Building of the Victoria & Albert Museum. The different factoring combinations and strategies, required by EC7, are compared in terms of the calculated design internal structural forces, illustrating that the use of more advanced models can have significant advantages. Moreover, comparisons are made between the design prop loads calculated from the FEM and a number of empirical methods. The HYD limit state, as described in EC7, relates to the upward flow of water through the soil towards a free surface. The HYD verification, using FEM, can be performed with two approaches; the soil block approach by calculating the equilibrium of a rectangular soil block and the integration point approach by checking that the equilibrium is satisfied at each integration point. Thorough comparisons between the two approaches using benchmark geometries illustrate the benefits of using more advanced approaches for such stability verifications.

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Kane, William F. „Geologic and geotechnical controls on the stability of coal mine entries“. Diss., Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/64668.

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Roof and rib failures in underground coal mines are one of the major problems facing the industry today. In addition to safety considerations, the resulting economic impact of such failures is staggering. Uncovering and replacing buried and damaged equipment and clearing entries can account for a large expenditure in lost man-hours and machinery. Yet, because of the complex nature of their formation, geological variability, and structural characteristics, coal mine roof strata are one of the least controllable of all mine design parameters. This is especially true along the leading (southeastern) edge of the Appalachian coalfields where considerable faulting and movement have contributed to hazardous coal mining roof conditions. For this research, a detailed study of several mines, in the southern Appalachian coalfields, was undertaken to determine the most prominent geomechanical factors affecting roof stability and to evaluate their influence in promoting unstable ground conditions. In order to accomplish this task, the major geological and geomechanical features found to be detrimental to the coal mine roof within the Appalachian basin were identified and mapped in four Virginia mines. Statistical processing by chi-square and linear regression analysis as well as analytical analysis by the finite element method were used to determine the influence of geology, mine-layout, and support methods on roof stability. It was found that some easily determined parameters can be successfully used to predict potentially unstable areas. A simplified roof classification system was developed based on the geomechanical parameters, which can be used to assess the stability of a particular roof type. A Roof Rating Index was also devised capable of expressing the probability of failure under a given set of geomechanical conditions.
Ph. D.

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Kiflu, Henok Gidey. „Optimized Correlation of Geophysical And Geotechnical Methods In Sinkhole Investigations: Emphasizing On Spatial Variations In West-Central Florida“. Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4709.

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Abstract Sinkholes and sinkhole-related features in West-Central Florida (WCF) are commonly identified using geotechnical investigations such as standard penetration test (SPT) borings and geophysical methods such as ground penetrating radar (GPR) and electrical resistivity tomography (ERT). Geophysical investigation results can be used to locate drilling and field testing sites while geotechnical investigation can be used to ground truth geophysical results. Both methods can yield complementary information. Geotechnical investigations give important information about the type of soil, groundwater level and presence of low-density soils or voids at the test location, while geophysical investigations like GPR surveys have better spatial coverage and can resolve shallow stratigraphic indicators of subsidence. In GPR profiles collected at 103 residential sites in covered-karst terrain in WCF, sinkhole-related anomalies are identified using GPR and SPT methods. We analyze the degree to which the shallow features imaged in GPR correlate spatially with the N-values (blow counts) derived from SPTs at the 103 residential sites. GPR anomalies indicating sinkhole activity are defined as zones where subsurface layers show local downwarping, discontinuities, or sudden increases in amplitude or penetration of the GPR signal. "Low SPT values" indicating sinkhole activity are defined using an optimization code that searched for threshold SPT value showing optimum correlation between GPR and SPT for different optimal depth ranges. We also compared these criteria with other commonly used geotechnical criteria such as weight of rod and weight of hammer conditions. Geotechnical results were also used to filter the data based on site characteristics such as presence of shallow clay layers to study the effectiveness of GPR at different zones. Subsets of the dataset are further analyzed based on geotechnical results such as clay thickness, bedrock depth, groundwater conditions and other geological factors such as geomorphology, lithology, engineering soil type, soil thickness and prevalent sinkhole type. Results are used to examine (1) which SPT indicators show the strongest correlations with GPR anomalies, (2) the degree to which GPR surveys improve the placement of SPT borings, and (3) what these results indicate about the structure of sinkholes at these sites. For the entire data set, we find a statistically significant correlation between GPR anomalies and low SPT N-values with a confidence level of 90%. Logistic regression analysis shows that the strongest correlations are between GPR anomalies and SPT values measured in the depth range of 0-4.5 m. The probability of observing a GPR anomaly on a site will decrease by up to 84% as the minimum SPT value increases from 0 to 20 in the general study area. Boreholes drilled on GPR anomalies are statistically significantly more likely to show zones of anomalously low SPT values than boreholes drilled off GPR anomalies. We also find that the optimum SPT criteria result in better correlation with GPR than other simple commonly used geotechnical criteria such as weight of rod and weight of hammer. Better correlations were found when sites with poor GPR penetrations are filtered out from the dataset. The odds ratio showed similar result while the result varied with the depth range, statistics and threshold SPT value (low N- value with optimum correlation), with a maximum observed odds ratio of 3. Several statistical results suggest that raveling zones that connect voids to the surface may be inclined, so that shallow GPR anomalies are laterally offset from deeper zones of low N-values. Compared to the general study area, we found locally stronger correlation in some sub-regions. For example, the odds ratio found for tertiary hawthorn subgroup were 25 times higher than the odds ratio found for the general study area (WCF).

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Arens, Kevin C. „Remediation Methods for Subgrade Settlements of Existing Roadways: Lifetime Cost-Benefit Analysis“. University of Dayton / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1575537943683836.

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Bloodworth, Alan Graham. „Three-dimensional analysis of tunnelling effects on structures to develop design methods“. Thesis, University of Oxford, 2002. http://ora.ox.ac.uk/objects/uuid:9c789d79-efa1-43fa-b2e1-e08d01de63db.

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The subject of this thesis is the verification of a three-dimensional numerical modelling approach for the prediction of settlement damage to masonry buildings due to tunnelling in soft ground. The modelling approach was developed by previous researchers at Oxford, and was applied to three sites, representative of a range of practical configurations. The first involved the excavation of a shaft close to the corner of an eighteenth century church in London. The second involved tunnelling with very low cover beneath the foundations of a terrace of cottages at Ramsgate, Kent. The third was the relatively well-known case of tunnelling beneath the Mansion House, London, for construction of the extension to the Docklands Light Railway in the late 1980’s. The overall conclusion of the project is that the modelling procedures are suitable for application to the detailed assessment of the response of buildings to tunnelling. Particular features of the procedures are that the building is modelled together with the ground and a representation of the tunnel excavation, and in three dimensions. It has been confirmed that all these features are necessary to model the building response, which may include a combination of shear deformation, arching and bending behaviour. Further lessons have been learned concerning the importance of the self-weight of the building in determining overall settlements, how to model openings such as doors and windows in façades, and whether it is necessary to model the building foundation. It has not proved possible, through lack of time, to model the advance of tunnels beneath buildings within this thesis. This, however, is observed to be an important effect in the field, particularly in causing damage to internal walls. It is recommended that further research be carried out in this area. This project made use of large-scale non-linear finite element analysis. The demand on computing resources was high, stimulating many enhancements to the software, the most important of which was parallelisation of the analysis program for use on the Oxford Supercomputer. To obtain optimum results, larger model sizes are required. The computing resources to enable this should become more commonly available within the next few years, enabling the modelling techniques to be used routinely.

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Martos, Justin Riley. „Fault Mapping with the Refraction Microtremor and Seismic Refraction Methods along the Los Osos Fault Zone“. DigitalCommons@CalPoly, 2012. https://digitalcommons.calpoly.edu/theses/873.

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The presence of active fault traces in proximity to any new infrastructure project is a major concern for the design process. The relative displacements that can be experienced in surface fault rupture during a seismic event must be either entirely avoided or mitigated in some way. Blind faults present a significant challenge to engineers attempting to identify these hazards. Current standards of practice employed to locate these features are time consuming and costly. This work investigates the geophysical methods of refraction microtremor (ReMi) and seismic refraction with regard to their applicability in this task. By imaging a distinct lateral variation in the shear wave velocity (Vs) profile across a short horizontal distance, these methods may provide a means of constraining traditional investigation techniques to a more focused area. The ReMi method is still very new, but holds key advantages over other geophysical methods in its ease of application and ability to achieve good results in highly urban settings. It is one of the few geophysical techniques that does not suffer in the presence of high amplitude ambient vibrations. The seismic refraction method is here applied in an attempt to corroborate data obtained through the ReMi analysis procedure. Sensitivity, precision parametric studies are carried out in order to learn how to best apply the ReMi method. Both tests are then applied at a previously trenched fault trace to determine whether the data can be matched to the subsurface information. Finally, the methods are deployed at a location with an inferred fault trace where little to nothing is known about the subsurface. The precision study indicates a coefficient of variation for the ReMi method on the order of 7%. At the known fault trace both methods generally agree qualitatively with available subsurface data and each other. Using the ReMi method, a marked shift is observed in the Vs profile laterally across the fault trace. In the case of the inferred fault trace, the same type of lateral variation in the Vs profile is observed using the ReMi method. The seismic refraction at this site does not agree with the ReMi data, but seems reasonable given the visible geomorphology. Receiver arrays placed in close proximity to the inferred fault trace recorded erratic signals during seismic refraction testing, and displayed abnormal response modes after transforming the ReMi data to frequency-slowness space. These anomalies may possibly be attributed to the presence of abnormal subsurface structural geometry indicative of faulting.

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Agreda, Principe Santos Oliver, und Ascencio Erick Andrés Avila. „Análisis probabilístico de riesgo geotécnico en excavaciones profundas utilizando anclajes post-tensados en edificaciones de Lima Metropolitana“. Bachelor's thesis, Universidad Peruana de Ciencias Aplicadas (UPC), 2020. http://hdl.handle.net/10757/652547.

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La presente investigación tuvo como objetivo principal, determinar el riesgo geotécnico de excavaciones profundas utilizando anclajes post-tensados en edificaciones de Lima Metropolitana, aplicando métodos probabilísticos a partir de un abordaje estadístico simple, basado en la hipótesis fundamental de la distribución normal gaussiana de las variables envueltas.En primer lugar, se utilizó el parámetro fundamental de los anclajes post-tensados, la capacidad última de adherencia en la interacción suelo-lechada de cemento τult, (resistencia en la ruptura). Este parámetro se obtuvo de dieciséis (16) ensayos de arrancamiento a escala natural de anclajes post-tensados cimentados en el conglomerado de Lima Metropolitana, obtenidos de la tesis de maestría de Puelles (2011). En segundo lugar, se realizó un diseño de anclajes post-tensados de edificaciones en Lima Metropolitana de 3, 4 y 5 anillos de 10.50, 13.50 y 16.50 m de profundidad respectivamente. Para ello, se utilizó la metodología FHWA con el objetivo de obtener la capacidad de carga de diseño (TD) de anclajes post-tensados. Además, se ejecutó modelos y modelamientos en el software Slide v6.0 (método equilibrio límite), para realizar el análisis de estabilidad de los mismos. Para ello, se tuvo en cuenta las siguientes variables: los parámetros geotécnicos representativos de Lima Metropolitana, la profundidad de estudio (10.50 a 16.50 m.) y la sobrecarga de edificaciones colindantes. Por último, con los parámetros obtenidos (τult y TD) se definió las curvas estadísticas de distribución de solicitación y resistencia. Luego, se aplicó los métodos probabilísticos e interpretación respectiva, determinado así el riesgo geotécnico para cada caso de estudio.
The main objective of this research was to determine the geotechnical risk of deep excavations using post-tensioned anchors in buildings in Metropolitan Lima, applying probabilistic methods based on a simple statistical approach, based on the fundamental hypothesis of the Gaussian normal distribution of the variables wrapped. Firstly, the fundamental parameter of the post-tensioned anchors was used, the ultimate capacity of adhesion in the soil-cement grout interaction τult, (resistance to rupture). This parameter was obtained from sixteen (16) natural scale pull-out tests of post-tensioned anchorages cemented in the conglomerate of Metropolitan Lima, obtained from the master's thesis of Puelles (2011). Secondly, a design of post-tensioned anchorages of buildings in Metropolitan Lima of 3, 4 and 5 rings of 10.50, 13.50 and 16.50 m depth, respectively, was carried out. For this, the FHWA methodology was used with the objective of obtaining the design load capacity (TD) of post-tensioned anchors. In addition, models and modeling were executed in the Slide v6.0 software (limit equilibrium method), to perform their stability analysis. For this, the following variables were taken into account: the representative geotechnical parameters of Metropolitan Lima, the study depth (10.50 to 16.50 m.) And the overload of neighboring buildings. Finally, with the obtained parameters (τult and TD) the statistical curves of the distribution of stress and resistance were defined. Then, the probabilistic methods and respective interpretation were applied, thus determining the geotechnical risk for each case study.
Tesis

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Carletto, Marcos Francisco Wosgrau. „Jet Grouting (sistema monofluido): um método teórico simplificado para a previsão do diâmetro das colunas“. Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/3/3145/tde-13102009-154059/.

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O jet grouting é uma das técnicas de tratamento de solos mais utilizadas em todo o mundo. Consiste em jatear uma calda de cimento a altíssima velocidade no subsolo, com ou sem a adição de água e/ou ar comprimido. Os fluidos são injetados através de minúsculos bicos posicionados na extremidade de uma composição especial de hastes, que giram à velocidade constante enquanto sobem lentamente em direção à superfície do terreno. O jato remove e mistura o solo, produzindo um corpo consolidado de formato aproximadamente cilíndrico (a coluna de jet grouting). Variando os parâmetros operacionais (pressão de bombeamento, quantidade e diâmetro dos bicos, velocidade de extração das hastes, relação água/cimento da calda) e em função do tipo de solo, podem ser obtidas colunas de diâmetros variáveis dentro de um amplo intervalo. Na busca do diâmetro desejado, a escolha dos parâmetros de tratamento é feita atualmente com base em regras empíricas nem sempre pertinentes, causando muitas vezes o fracasso do tratamento ou, ainda, tornando-o excessivamente oneroso. Esta tese de doutorado apresenta um método simplificado para a previsão do diâmetro das colunas de jet grouting (sistema monofluido). Conjugando a análise racional do fenômeno físico de interação jatosolo (Modoni et al., 2006) à facilidade de aplicação característica dos métodos empíricos, propõe-se uma ferramenta ágil para a escolha da combinação mais adequada dos parâmetros de tratamento.
Jet grouting is one of the most popular ground improvement techniques all over the world. The method is based on high-speed grouting of water-cement mixtures and/or other fluids (air, water) into the subsoil. The fluids are injected through small diameter nozzles placed on a grout pipe, which is continuously rotated at a constant rate and slowly raised towards the ground surface. The jet removes and mixes the soil, producing a cemented body of quasi-cylindrical shape (the jet grouting column). Varying the operational parameters (grout pressure, number and diameter of the nozzles, monitor lifting rate, water-cement ratio of the grout) and as a function of the soil type, columns of variable diameters can be obtained in a wide interval. Currently, in search of the required diameter, the choice of the operational parameters is done on the basis of empirical rules not always relevant, causing very often the failure of the treatment or making it excessively onerous. This thesis presents a simplificated method for the prediction of the column diameter (single fluid system). Conjugating the rational analysis of the physical phenomenon of jetsoil interaction (Modoni et al., 2006) to the typical easiness of empirical methods application, an agile tool is proposed for the choice of the most appropriate combination of the operational parameters.

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Santos, Stephane do Nascimento. „Simulação numérica de dutos enterrados, submetidos à perda de apoio e elevação localizada“. Universidade do Estado do Rio de Janeiro, 2014. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=9092.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Os recentes desastres ocorridos no país, como o rompimento da adutora em Campo Grande e os desastres relacionados às enchentes urbanas, mostram a necessidade de desenvolvimento de pesquisas científicas que auxiliem na compreensão e no dimensionamento das estruturas projetadas para atender a demanda da população. Os métodos analíticos e experimentais mais utilizados possuem algumas limitações de ordem teórica ou prática. Por outro lado, os métodos numéricos, capazes de simular etapas construtivas e envolver materiais com diferentes modelos constitutivos numa mesma análise, buscam atender às necessidades práticas dos projetos de geotecnia e, ao mesmo tempo, complementam os modelos analíticos e experimentais. Nesse trabalho foram realizadas comparações entre resultados obtidos em ensaios experimentais e resultados extraídos do modelo computacional, buscando aumentar a compreensão sobre a interação solo-estrutura em relação à distribuição de tensões mobilizadas e aos deslocamentos e deformações provocados. A simulação numérica foi feita com a utilização do PLAXIS/3D, software de análise geotécnica baseado no método dos elementos finitos. Os ensaios foram confeccionados na Escola de Engenharia de São Carlos/USP por Costa (2005) e envolveram dutos enterrados submetidos à perda de apoio ou elevação localizada. O estudo experimental foi realizado através de modelos físicos compostos por um maciço de areia pura, contendo um tubo repousando sobre um alçapão no centro do vão. Os modelos físicos foram equipados com instrumental capaz de medir as deflexões e as deformações específicas ao longo do duto, além das tensões totais no maciço de solo circundante e na base do equipamento.
Recent disasters that occurred in this country, like the failure of a pipeline in Campo Grande and others disasters related to urban flooding, show us the need for developing scientific researches that help us to understand the behavior of these structures and to design them to serve the population. Analytical and experimental methods have some theoretical and practical limitations. On the other hand, numerical methods are capable to simulate staged constructions and to analyze together materials with different constitutive models, supplying practical necessities of geotechnical projects and complementing analytical and experimental models. In this dissertation comparisons between experimental results and numerical results have been made, trying to increase the comprehension about the interaction of soil and pipe with respect to mobilized stress distribution, displacements and strains. The numerical modeling was performed on PLAXIS 3D software, based on Finit Elements Method. The experimental test was made by Costa (2005) at São Carlos Engineering School/USP and involved buried pipes undergoing loss of support or elevation in a localized region along its length. Tests have been performed with physical models comprising dry and pure dry sand and a tube resting on a rigid trapdoor base located at the center of its length. The models were equipped with devices for measuring deflections and strains in the pipe, and total stresses in soil mass and in the lower boundary of the model.

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Ho, David Kar Hung. „Analyses of geotechnical construction by the finite element method“. Thesis, University of Manchester, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.277388.

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Ranjineh, Khojasteh Enayatollah [Verfasser], Thomas [Akademischer Betreuer] Ptak-Fix, Martin [Akademischer Betreuer] Sauter, Xavier [Akademischer Betreuer] Emery und Raimon [Akademischer Betreuer] Tolosana-Delgado. „Geostatistical three-dimensional modeling of the subsurface unconsolidated materials in the Göttingen area : The transitional-probability Markov chain versus traditional indicator methods for modeling the geotechnical categories in a test site / Enayatollah Ranjineh Khojasteh. Gutachter: Martin Sauter ; Xavier Emery ; Raimon Tolosana-Delgado. Betreuer: Thomas Ptak-Fix“. Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2013. http://d-nb.info/1044769602/34.

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Bandara, Samila Sanjeevanie. „Material point method to simulate large deformation problems in fluid-saturated granular medium“. Thesis, University of Cambridge, 2013. https://www.repository.cam.ac.uk/handle/1810/283928.

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Serna, Marcelo Alejandro Llano. „Experimental and numerical study of geotechnical problems using the material point method“. reponame:Repositório Institucional da UnB, 2016. http://repositorio.unb.br/handle/10482/22294.

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Tese (doutorado)—Universidade de Brasília, Faculdade de Tecnologia, Programa de Pós-Graduação em Geotecnia, 2016.
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O objetivo deste trabalho é investigar os mecanismos de alguns problemas geotécnicos submetidos a grandes deformações, e mais especificamente o cone de penetração e escorregamentos na área de estabilidade de taludes. O fenômeno de grandes deformações em Geotecnia pode ser observado em problemas de ensaios de campo como SPT, CPT, DMT; ensaios de laboratório como o ensaio de cone e de palheta; em aplicações práticas como a cravação de estacas e em encostas após a ruptura de um talude. Uma das principais limitações na prática da engenharia geotécnica é que as formulações tradicionais para o cálculo de estruturas dependem da hipótese de pequenas deformações. Na última década, com o aumento da capacidade computacional e surgimento de novos métodos numéricos, tornou-se factível a modelagem numérica de problemas de grandes deformações, gerando a possibilidade de estudá-los em maior detalhe. Este trabalho centra-se na aplicação do Método do Ponto Material (MPM). O MPM é uma ferramenta numérica que adota um esquema de discretização Euleriano-Lagrangiano, o que fornece um esquema sofisticado para resolver o balanço de momento linear quando se observam grandes deformações. O método foi aplicado à análise de ensaios de penetração de cone em laboratório e a problemas reais de escorregamentos de taludes com grandes movimentos de massa. Inicialmente, foram feitos ensaios diretos e indiretos de resistência ao cisalhamento em amostras de caulim. O programa de ensaios de laboratório inclui o ensaio de palheta, ensaio de cone, ensaio de compressão oedométrica e ensaio de compressão triaxial convencional. Como produto dos ensaios de laboratório, foram propostas algumas relações entre parâmetros de estados críticos e o ensaio de queda de cone. Também baseado nos ensaios de laboratório, o programa NairnMPM foi testado e calibrado para resolver problemas geotécnicos simples como o ensaio de cone e o colapso de uma coluna de solo. Depois disso e com o intuito de verificar a capacidade do MPM para resolver problemas de grande escala, foram simulados os escorregamentos de taludes na barragem de Vajont, na Itália, e na rodovia Tokai-Hokuriku, no Japão. Finalmente, foi testado o processo de modelagem do escorregamento de Alto Verde, na Colômbia, e as variáveis dinâmicas previstas no modelo foram usadas no cálculo de risco. Os resultados se ajustaram muito bem às observações de campo, destacando a potencialidade do MPM como ferramenta prática na modelagem de vários problemas de grandes deformações na engenharia geotécnica.
The goal of this work is to investigate the mechanisms of various geotechnical problems subjected to finite strains, more specifically the fall cone test and run-out process during landslides. Large deformation phenomena may be observed in field testing such as SPT, CPT, DMT; laboratory testing such as fall cone test, mini-vane test, and practical problems such as pile driving and run-out process during landslides. The main limitations in the practice of geotechnical engineering are due to the fact that a wide number of design frameworks are based on the small strain hypothesis. In the last decade, with the increasing computational capacity and the development of novel numerical methods; solving large deformation models have become feasible. This fact allows studying in detail a wide number of phenomena in geotechnics. This work focuses on the application of the Material Point Method (MPM). The MPM is a numerical tool that adopts a Eulerian-Lagrangian scheme. Moreover, it allows a solid framework to solve the linear momentum balance when finite strains are observed. The method was used in the simulation of the fall cone test and real scale mass movements in landslides. Initially, direct and indirect shear strength measurements on kaolin clay were performed. The laboratory testing program included mini-vane shear test, fall cone test, oedometric compression, and conventional triaxial compression test. As a result of the laboratory testing, interesting relationships between the critical state parameters and the fall cone were established. Furthermore, NairnMPM open source code was tested and calibrated using the laboratory results to later solve simple geotechnical problems such as fall cone test and the collapse of a soil column. Afterwards, the possibility of simulating real-scale problems in landslides was addressed. The slope failure in Vajont, Italy, and Tokai-Hokuriku Expressway, Japan, were considered. Finally, the framework was tested in a landslide in Alto Verde, Colombia. The computed dynamic quantities were used in risk assessment of landslides. The results matched very well with field observations highlighting the potential of using MPM as a practical tool for modelling various problems involving large strains in geotechnical engineering.

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Silva, Felipe Nascimento da. „Análise de critérios de dimensionamento de carga em dutos de concreto instalados em vala na situação de recobrimento mínimo“. Universidade do Estado do Rio de Janeiro, 2014. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=8675.

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Perante diversas situações da engenharia são utilizadas formulações empíricas de dimensionamento baseadas em dados de campo e experiência profissional que definem muito o caráter subjetivo da metodologia padrão de projeto. O presente trabalho de pesquisa aborda os diversos métodos de obtenção dos esforços gerados em dutos enterrados submetidos a cargas dinâmicas e estáticas e sua posterior reavaliação através de modelagem numérica com o programa Plaxis 3D. Os métodos analíticos não convencionais foram comparados com o método padrão de cálculo sendo que o mesmo demonstrou ter uma boa precisão mesmo sem considerar outros fatores importantes como a parcela de resistência devida à coesão do solo e sua deformabilidade. A modelagem numérica demonstrou o conservadorismo do método de Marston e o subdmensionamento do espraiamento em prisma devido aos efeitos locais ocasionados pela adoção do recobrimento mínimo e sobrecarga dinâmica elevada. Também se observou, através da modelagem 3D, que a utilização dos dois métodos clássicos favorecem a obtenção de resultados dentro da razoabilidade.Verificou-se também, como resultado desta pesquisa, que a proposta de um método clássico modificado permite uma melhor aproximação da carga que atinge o duto.
In various engineering situations, empirical formulations of design, based on field data and professional experience which highly define the subjective nature of the standard design methodology, are used. This paper discusses the various methods of obtaining the stresses generated in buried pipelines, which are subjected to static and dynamic loads, and their subsequent re-evaluation by numerical modeling with Plaxis 3D program. The non-conventional analytical methods were compared with the standard method of calculation and it has demonstrated good accuracy even without considering other factors such as soil cohesion and deformability. The numerical modeling demonstrated the conservatism of the Marston method and subsiding of the prism spread due to local effects caused by the adoption of minimum cover and high dynamic overload and due to how the use of two classical methods favor reasonable results. A classic modified method that would allow a closer approximation of the load was also proposed.

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McKay, Sara E. „Geotechnical analysis of horizontal drains as a landslide mitigation method in western Washington /“. abstract and full text PDF (free order & download UNR users only), 2006. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1437660.

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Thesis (M.S.)--University of Nevada, Reno, 2006.
"August, 2006." Includes bibliographical references (leaves 93-97). Library also has microfilm. Ann Arbor, Mich. : ProQuest Information and Learning Company, [2006]. 1 microfilm reel ; 35 mm. Online version available on the World Wide Web.

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Zhou, Hongjie. „Numerical study of geotechnical penetration problems for offshore applications“. University of Western Australia. Centre for Offshore Foundation Systems, 2008. http://theses.library.uwa.edu.au/adt-WU2008.0239.

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The research carried out in this thesis has concentrated on the application of numerical solutions to geotechnical penetration problems in offshore engineering. Several important issues closely relevant to deep-water oil and gas developments were investigated, covering installation of suction caisson foundations, interpretation of fullflow penetrometers and shallow penetration of a cylindrical object (submarine pipeline or T-bar), all in clayey sediments such as are often encountered in deep-water sites. These problems are commonly characterised by large vertical movements of structural elements relative to the seabed. A large deformation finite element method was adopted and further developed to simulate these challenging problems, referred to as Remeshing and Interpolation Technique with Small Strain. In this approach, a sequence of small strain Lagrangian increments, remeshing and interpolation of stresses and material properties are repeated until the required displacement has been reached. This technique is able to model relative motion between the penetrating objects and the soil, which is critical for evaluating soil heave inside the caissons, the effect of penetration-induced remoulding on the resistance of full-flow penetrometers, and influence of soil surface heave on the embedment of pipelines. '...' Simple expressions were presented allowing the resistance factors for the T-bar and ball penetrometers to be expressed as a function of the rate and strain-softening parameters. By considering average strength conditions during penetration and extraction of these full-flow penetrometers, an approximate expression was derived that allowed estimation of the hypothetical resistance factor with no strain-softening, and hence an initial estimate of the stain-rate dependency of the soil. Further simulations of cyclic penetration tests showed that a cyclic range of three diameters of the penetrometers was sufficient to avoid overlap of the failure mechanism at the extremes and mid-point of the cyclic range. The ball had higher resistance factors compared with the T-bar, but with similar cyclic resistance degradation curves, which could be fitted accurately by simple expressions consistent with the strain-softening soil model adopted. Based on the curve fitting, more accurate equations were proposed to deduce the resistance factor with no strain-softening, compared with that suggested previously based on the resistances measured in the first cycle of penetration and extraction. The strain-rate dependency was similar in intact or post-cyclic soil for a given rate parameter. The resistance factor for the post-cyclic condition was higher than that for the initial conditions, to some degree depending upon soil sensitivity and brittleness parameter. For the shallow penetration of a cylindrical object, the penetration resistance profile observed from centrifuge model tests was very well captured by the numerical simulation. The mechanism of shear band shedding was reproduced by the numerical technique, although the frequency of the shear band generation and the exact shape of the heave profile were not correctly captured, which were limited by the simple strainsoftening soil model adopted.

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Bertel, Jeffrey D. „Analytical study of the spectral-analysis-of-surface-waves method at complex geotechnical sites“. Diss., Columbia, Mo. : University of Missouri-Columbia, 2006. http://hdl.handle.net/10355/4625.

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Thesis (M.S.) University of Missouri-Columbia, 2006.
The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on August 21, 2007) Includes bibliographical references.

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Javakhishvili, Zurab. „The coupled finite-boundary element method applied to the analysis of geotechnical engineering problems“. Thesis, London South Bank University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261020.

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Yan, Li. „Hydraulic gradient similitude method for geotechnical modelling tests with emphasis on laterally loaded piles“. Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/31899.

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A study has been undertaken to evaluate and apply the hydraulic gradient similitude method to geotechnical model testings. This method employs a high hydraulic gradient across granular soils to effectively increase self-weight stresses in the model. Testing principle and procedures are presented, and the factors affecting test results discussed. An apparatus (UBC-HGST) using this testing principle has been developed. Three applications are presented in which the hydraulic gradient similitude method is evaluated, and the existing concepts and methods of analysis for the problems studied are examined. In the footing tests, it is found that the scaling laws implied in the hydraulic gradient modelling test are satisfied, and are similar to those of the centrifuge modelling technique. Load-settlement curves are found to be similar to those in centrifuge tests. The test results illustrate the importance of the stress level in the load-settlement responses. Terzaghi's bearing capacity formula is compared with the observed bearing capacities under different stress levels. It is found that due to the stress level effects, the bearing capacity coefficient, Nγ, decreases linearly with footing width on the log-log scale which is in accordance with other model study and analytical results. In the downhole and crosshole seismic tests, results are used to evaluate the empirical equations that relate shear wave velocity and soil stresses in terms of field stress condition. It is found that although the various equations can predict the insitu shear wave velocity profile reasonably well, only the equation which is based on the significant stresses in the wave propagation and particle motion directions can predict the variation of velocity ratio between the downhole and SH crosshole tests. It is also found that the stress ratio has some effects on the downhole (or SV crosshole) tests, but not on the SH crosshole tests. This indicates that only the stress ratio in the plane of wave propagation is important to the shear wave velocity. Comparison between the downhole and SH crosshole tests shows that the structure anisotropy was about 10% in terms of shear wave velocity. Prediction of Ko values using shear wave measurement is evaluated, and its practical difficulties are addressed. In the laterally loaded pile tests, the pile response to static and cyclic loadings at various stress levels controlled by the hydraulic gradients is examined in terms of pile head response, pile bending moment and soil-pile interaction P-y curves. For the static loading, pile head response and bending moment are found to be significantly affected by the soil-pile relative stiffness, pile diameter, loading condition and pile head fixity. However, little effects of loading eccentricity and pile head fixity are found on the P-y curves. While pile diameter is found to have effects on the P-y curves at large pile deflection, its effects are negligible at small deflecton range. The effects of relative soil-pile stiffness on the P-y curves due to stress levels can be normalized by the soil modulus and pile diameter for the curves below 1 pile diameter, as computed by the plane strain finite element analysis. Two methods of generating P-y curves are suggested, and found to give satisfactory results as compared with the test data and the prediction given by API code (1987). For cyclic loading, different pile responses are observed in "one-way" as compared to "two-way" cyclic loading. The cyclic P-y curves are derived, and found to be highly nonlinear and hysteretic, and change with number of loading cycles. From these studies, it is shown that the hydraulic gradient similitude method provides a simple and inexpensive means of model testing for many geotechnical engineering problems and adds to the data base from which methods of analysis can be evaluated.
Applied Science, Faculty of
Civil Engineering, Department of
Graduate

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Černý, Vít. „Optimalizace geotechnického průzkumu a monitoringu při navrhování a provádění podzemních staveb“. Doctoral thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-234559.

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The presented thesis focuses primarily on issues of geotechnical survey and geotechnical monitoring for underground line constructions. It deals with the current practice of geotechnical survey and monitoring. Based on the knowledge gained from specific buildings in the Czech Republic (Královopolské tunnels, tram tunnel Žabovřeská) and based on the author's practical local and foreign experience submits suggestions regarding their mutual optimization in order to improve outputs and reduce financial costs.

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Kang, GiChun. „Assessing uplift displacement of buried geotechnical structures in liquefied ground during earthquakes“. 京都大学 (Kyoto University), 2010. http://hdl.handle.net/2433/120829.

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Granskär, Joakim. „Evaluation of SCPT-surveys as method for accessing dynamic modulus“. Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-68756.

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The purpose of this master thesis is to evaluate the results from the completed SCPT (Seismic Cone Penetration Test) surveys with respect to the methods ability to estimate dynamic young´s modulus. This has been done by comparing the result from SCPT to other seismic methods and dynamic parameters converted from “static” geotechnical surveys. SCPT is a relatively new method which has not been used by Sweco or in Sweden to any greater extent and is therefore of interest to be looked in to. By adding two geophones to an ordinary CPT (Cone Penetration Test) equipment as well as including strike plates, hammer and logger system one can log dynamic parameters in addition to the regular parameters logged by a CPT system. This is done by stopping the otherwise continuous CPT survey every meter and striking the strike plates, which are placed under the tracks of the drilling rig. Seismic waves will then travel through the soil down to the geophones and be used to calculate dynamic parameters. For this master thesis a total of 47 geotechnical and geophysical surveys have been considered. The location of these 47 are approximately 7 km north of Norrköping and have been conducted between the years 2016-2017 for the East Link Project. The geotechnical surveys are composed of weight-sounding, ram-sounding and CPT while the geophysical ones are SCPT, refraction-survey and MASW (Multichannel Analysis of Surface Waves). Static elastic parameters have been calculated using the geotechnical survey results according to the Swedish transportation administrations standardized methods. These have then been converted to dynamic parameters with the help of different relationships. When these have been converted they can be compared to SCPT results and other seismic survey methods which also use wave velocity, Poisson’s ratio and density to calculate dynamic elastic parameters. Based on the results from this thesis it can be concluded that the seismic test add-on to a standard CPTu survey is a good method for accessing dynamic modules and it gives extended information of the soil stratigraphy from one single survey point. After the studies and analyses conducted for this thesis it can be concluded that the proposed conversion between static and dynamic young’s modulus using the Alpan curve gives slightly higher values than the ones derived directly from shear waves using SCPT. The other conversion using cone tip resistance to shear wave velocity gives on the other hand slightly lower values than the ones measured with the SCPT. The analysis also indicate similar trends in results between the different seismic methods. These results does however also shows that the used assumptions are somewhat general for accurate comparisons between the methods.

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Wendlandt, Nichole Jean. „A Geotechnical Evaluation of the Launched Soil-Nailing Method of Landslide Stabilization in Summit County, Ohio“. Kent State University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=kent1239813377.

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GUTIERREZ, LUCAS LUDEÑA. „FORMULATION AND SOME APPLICATIONS OF MATERIAL POINT METHOD IN GEOTECHNICAL PROBLEMS IN STATIC AND DYNAMIC CONDITIONS“. PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2016. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=33844@1.

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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO
COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
PROGRAMA DE EXCELENCIA ACADEMICA
Em problemas geotécnicos podem ocorrer grandes deformações devido a chuvas prolongadas, sismos, deslizamentos de encostas, etc. Material point method (MPM) é um método de solução baseado no Método dos Elementos Finitos (MEF) que oferece vantagens para o cálculo estático e dinâmico que envolve deformações desse tipo. O objetivo desta dissertação é utilizar o MPM em problemas geotécnicos em condições estáticas e dinâmicas. Esta pesquisa mostra o procedimento de analises do MPM para a condição não acoplada (só solido sem presença de água) e depois acoplada. Para a revisão matemática de MPM se faz antes um resumo da teoria do MEF na metodologia de conservação de quantidade de movimento. Nestas duas formas de resolver os problemas geotécnicos foram expostos três exemplos simples. O primeiro é uma coluna de solo simulado sob os fundamentos da elasticidade, com o objetivo de verificar o deslocamento vertical pelo peso próprio. Isto foi resolvido mediante quatro diferentes métodos: analítica, MEF por resíduos ponderados, MEF por conservação de quantidade de movimento, e MPM. Todos eles consideram somente a fase solida. No segundo exemplo, tem-se solo na geometria de quadrado de lado 1 metro, onde busca-se obter as poropressões quando atingir a condição permanente enquanto os deslocamentos ocorrem ao longo do tempo; ou seja, a análise é acoplada e é resolvida pelo método MPM. Para uma aplicação mais realista, foi feita a análise (não acoplada) da barragem Palo Redondo, pertencente ao projeto Chavimochic, localizada na região de La Libertad, Perú. Nesta análise dinâmica considerou-se dois modelos constitutivos: Elástico e Mohr Coulomb, além de um sismo.
In geotechnical problems can happen large strains because of prolonged rains, earthquake, slide slope, etc. Material point method is a solution method based on the finite element method (FEM) which offers advantages for static and dynamic calculation that involve that kind of strains. The objective in this dissertation is to use the MPM in geotechnical problems in statics and dynamics conditions. This research shows the analysis procedure of MPM for uncoupled condition (only solids, without water) and then coupled. Before the mathematical theory of MPM, a review of the theory of FEM in the conservation of quantidade de movimento is done. In this two methodology were raised three examples. The first one is a soil column that was modeled elastically, in which the main objective in to analyze the vertical displacement because of own weight. This was solved by four different methods: analytically, FEM weighted residual, FEM conservation of momentum, and MPM. All of them consider only the solid phase. The second example is a square of soil with side 1 meter, where the objective is to know the pore-pressure in the permanent condition and at the same time the vertical displacement were generated, it means that the analysis is coupled and were solved by MPM. In order to make a more realistic application, Palo Redondo dam is analyzed (uncoupled condition), which belongs to the Chavimochic project located in La Libertad, region of Perú. This dynamic analysis was done considering two constitutive models: Elastic and Mohr Coulomb, additionally seismic forces.

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Wetterová, Alice. „Řešení stability svahu v náročných geotechnických podmínkách“. Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2012. http://www.nusl.cz/ntk/nusl-225706.

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Aim of the diploma thesis is design elements of slope stabilization in accordance with the planned highway D3 in Slovakia section of Cadca, Bukov - Svrčinovec and relocation of a local road. Objective subject is situated on the slopes of Cadca. In diploma thesis is an analysis of the area with the proposed stabilizing elements in the 5 GEO FEM, their assessment, including determining the overall stability of the territory according to the degree of safety.

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Brinck, Mårten, und Karl Stigenius. „Jet grouting as a method for sealing sheet pile excavations in Swedish conditions : A probabilistic approach“. Thesis, KTH, Jord- och bergmekanik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-259693.

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Jet grouting is a groundimprovement method that creates cemented columns in the soil. The soil isinjected with different pressurized fluids, through the monitor, to replace andcement the soil, often with water cement grout. There are three different commonsystems for ejecting the fluids, the single, double and triple fluid system.The process is performed from the ground surface by drilling to desired depthand then withdrawing the monitor while rotating and ejecting and thus creatinga column. There are many applications for this technique. However, this thesisfocus on using jet grouted columns in formation to seal sheet pile excavationsfrom water.

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Silva, João Paulo de Sousa. „Avaliação da influência do regime de fluxo no comportamento geotécnico de uma barragem de rejeito alteada pelo método de montante“. Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/3/3145/tde-28082015-145835/.

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A presente pesquisa faz uma avaliação da influenciado regime de fluxo na estabilidade de uma barragem construída pela disposição hidráulica de rejeitos. Usualmente, essas estruturas são avaliadas com modelos de equilíbrio limite adotando-se, de modo simplificado, uma superfície freática em um regime hidrostático. No entanto, em casos em que a condutividade hidráulica da fundação ou de camadas na base do aterro é relevante em relação à dos rejeitos, o fluxo se torna verticalizado e o gradiente significativo, portanto, a premissa de regime hidrostático se torna não válida. Com o objetivo de avaliar a influência desses fatores, foram realizadas análises numéricas, simulando condições de fluxo e seus reflexos nos fatores de segurança. Ademais, foi desenvolvida uma extensa análise de dados e cálculos no estudo de caso de uma barragem, com expectativa de ampliar a vida útil de uma Planta de beneficiamento de minério de ferro. Ao se incorporar a real distribuição de pressões neutras, medidas na barragem, concluiu-se que o seu Fator de Segurança era cerca de 20% maior do que o obtido em cálculos simplificados, que desconsideram o regime de fluxo descendente, admitido, por hipótese, na barragem em estudo. Alguns comentários quanto à segurança à liquefação foram feitos, exceto a liquefação dinâmica, que foge do escopo desse trabalho.
The present research evaluates the influence of the foundations permeability in the scheme of flow and in the stability of a dam built through the hydraulic tailings disposal. Usually, these structures are evaluated with models of equilibrium limit, considering, in a simplified way, a phreatic surface in a hydrostatic scheme. However, in cases in which the foundations hydraulic conductivity is relevant when related to the tailings, the flow becomes verticalized and the gradient becomes significant. Therefore, the hydrostatic scheme premise becomes not valid. With the purpose of evaluating the influence of these factors, numerical analysis were made, simulating flow conditions and their influence in the factor of safety. Moreover, an extensive data and calculations analysis was developed in the case study of a dam, with the expectation of increasing the lifetime of an ore mining beneficiation plan. When incorporating the actual distribution of porepressure, measured at the dam, it was concluded that the safety factor of the dam was about 20% higher than that obtained for simplified calculations, that disregard the downward flow regime, admitted in the dam under study. Some comments about the safety of liquefaction were made, except the dynamic liquefaction, beyond the scope of this work.

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Ravjee, Sachin. „Discrete element modelling investigating the effect of particle shape on backfill response behind integral bridge abutments“. Diss., University of Pretoria, 2018. http://hdl.handle.net/2263/64125.

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Integral bridges are designed without expansion joints or bearings to eliminate the maintenance and repair costs associated with them. Thus, the expansion and contraction due to daily and seasonal temperature variations of the deck of the bridge are restricted by the abutments, causing the abutments to move cyclically towards and away from the granular material used as backfill. This movement results in a stress accumulation in the backfill retained by the abutments. The Discrete Element Method (DEM) was used was used to perform a numerical sensitivity analysis, investigating the effect of granular particle shape on the response of backfill material retained by integral bridge abutments. Two DEM software suites were used to perform the simulations, namely STAR-CCM+, a commercial code, and Blaze-DEM, a research code under development at the University of Pretoria. Blaze-DEM makes use of Graphics Processing Unit (GPU) computing as opposed to traditional Central Processing Unit (CPU) computing. Blaze-DEM delivered computational times over 150 times faster than the equivalent simulation in STAR-CCM+. The results from the numerical sensitivity analysis showed that the particles with lower sphericities (higher angularities) experienced larger accumulations of stresses on the abutment as opposed to the more spherical particles. This was suggested to be a result of particle interlocking and reorientation.
Dissertation (MEng)--University of Pretoria, 2018.
Civil Engineering
MEng
Unrestricted

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Ratel, Alain. „Modélisation d'un sol renforcé par géosynthétique : application de la "méthode en déplacements"“. Grenoble 1, 1987. http://www.theses.fr/1987GRE10110.

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Pour les sols renforces, en particuler pour ouvrages de soutenements, etude du phenomene de l'interaction et proposition d'une nouvelle methode d'equilibre limite dite des "deplacements", prenant en compte la deformabilite du geotextile; nombreux exemples de calculs

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Emanuelsson, Patrik. „Study of a new method to measure the stresses in rock by image technology : Use of sawn slots and DIgital Image Correlation“. Thesis, Luleå tekniska universitet, Geoteknologi, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-68646.

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In rock constructions and mining it is important to know the current stress situation in the rock due to safety and construction reasons. Two of the widely used stress measurement methods are overcoring and hydraulic fracturing. Both methods are expensive, need new boreholes, and are complex and time consuming. The methods are also limited by the number of successfully achieved measurements series. An alternative method is therefore investigated by locally relieving stresses around the borehole wall using sawn slots. To determine the stresses in the rock, strain measurements will be done using optics and image processing of images taken before and after cutting of the slots. The images will be processed by a technique called Digital Image Correlation (DIC), a method where the pixels are fitted between the images by the greyscale. The thesis is roughly divided into three parts. The first part explains the basics of rock stresses and current stress measurement methods. The second part is a literature study of the theory behind optics and DIC. There is also a study about if it is possible to use optics from a smartphone and how it differs from a reference commonly used camera in DIC application. Last part consists of numerical calculations in 2D to investigate if there is a possibility to relieve the stress around the borehole walls by cutting slots. With the optics from a smartphone the borehole wall can be in focus on just a few millimeters distance. DIC is a well-developed method which has a good precision when being conducted right and with a good image quality. The combination of using a smartphone and DIC is, however, not fully investigated yet. Only one comparable study was found. It used a Sony tablet and measured the deformations instead of strains. However, that study showed that the measurement error was around 1% compared to the reference camera. When translating deformations into strains, it is most likely that the error will increase, because the error will also be affected from the difference in deformation before and after cutting the slots. The numerical part showed that it’s possible to relieve the stress at parts of the borehole walls for the investigated conditions. To fully relieve the stresses around the borehole wall, it is necessary to have two slots with a short c-c distance and relatively deep slots. In this case a c-c distance of 15 mm and slot depth of at least 25 mm are recommended.
Vid projekt inom berganläggningar och gruvor är det viktigt att känna till de rådande spänningar i berget i ett säkerhets- och konstruktionsperspektiv. I Sverige används framförallt två undersökningsmetoder - överborrning eller hydraulisk spräckning. Två metoder som dock är dyra och relativt få mätserier kan genomföras. En alternativ metod har därför undersökts där borrhålsväggen lokalt avlastas genom sågade slitsar. Töjningsmätning sker genom att fotografera borrhålsväggen innan och efter sågning av slitsarna. Därefter sker bildbehandling via Digital Image Correlation (DIC). En metod som jämför en pixels placerings förändring genom att matcha pixeln via gråskalan. Examensarbetet kan man säga är grovt indelat i tre delar. Den första delen innefattar teorin som handlar om bergspänningar samt nuvarande mätmetoder för att mäta bergsspänningar. Andra delen är en litteraturstudie som behandlar den bakomliggande teorin för optik och bildbehandling med DIC samt en kort undersökning om det är möjligt att använda den optiska tekniken som finns i en smartphone. Sista delen utgörs av numeriska modelleringar i 2D för att verifiera om det går att fullständigt avlasta ett borrhål genom sågade slitsar. Med optik som finns i en smartphone kan bergväggen vara i fokus på bara ett par millimeters avstånd. DIC i sig är en teknik som är så pass utvecklad att precisionen i mätningarna är väldigt god. Förutsatt att bildbehandling görs korrekt och bildkvalitén är god. Kombinationen med optik liknande den från smartphone och bildbehandling med DIC är dock inte fullständigt undersökt. Enbart en jämförbar studie har hittats där deformationsmätningar har gjort med hjälp av en Surfplatta från Sony. Denna undersökning visade att mätfelet mot en referenskamera är cirka 1%. Dock förstärks mätfelet vid töjningsmätningar. Förstärkningen beror dock även av deformationsskillnaden mellan innan och efter avlastning. Den numeriska delen har visat att det går att lokalt avlasta bergväggen fullständigt för det undersökta spänningsförhållandet. Dock krävs det att två slitsar sitter på ett litet c-c avstånd samt är relativt djupa. Två undersökta slitsuppsättningar har visat på fullständigt avlastning, samt ytterligare ett fall som skulle kunna vara användbart.

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Modenese, Chiara. „Numerical study of the mechanical properties of lunar soil by the discrete element method“. Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:c8908ef8-9652-4e8d-9b2f-49770f3ce815.

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Lunar soil, defined as the finest part of the lunar regolith which covers the entire surface of the Moon, has shown to have remarkable shear strength properties, highlighted by the clearly visible effects of soil cohesion. The main objective of this thesis is to unveil the physical explanations causing this unusual soil behaviour in a waterless, airless, lunar environment. Ultra-High Vacuum (UHV), in particular, is considered responsible for increasing the strength of surface energy forces due to lunar soil outgassing. In turn, the presence of surface energy forces, arising from van der Waals intermolecular forces, is thought to alter the mechanical properties of lunar soil. A particle-based microscopic approach by means of the Discrete Element Method (DEM) was utilised to investigate the effects of surface energy forces on the macroscopic soil be- haviour. A micro-mechanical contact model, based on the JKR theory, was selected to describe the inter-granular behaviour between lunar soil particles. Physical and geometrical parameters typical of lunar soil were employed. Several triaxial tests were run to identify a link, if any, between the microscopic surface energy parameter and the macroscopic soil cohesion, which was interpreted as a true soil cohesion. In addition, very low stress levels and high soil densities were simulated in order to take into account the low gravitational field and the high state of soil compaction caused by continuous meteorite impacts on the Moon. Results from triaxial tests were analysed at both the peak and critical state. It was found that in the ideal case of perfectly spherical grains, the presence of adhesion is a source of noticeable macroscopic soil cohesion. However, no influence was observed in terms of macroscopic friction angle. Furthermore, a brittle macroscopic soil behaviour was revealed, owing to the simulated inter-granular chemical bonds and the very low stress conditions applied. Finally, similar to the behaviour of cemented sands, very little cohesion was recorded at the critical state. Subsequently, particle shape effects were investigated by complementing the numerical model with a simple form of inter-particle rolling resistance. Simulations were also run with non-convex grains of increasing geometrical complexity in order to simulate more realistically the irregular shapes of lunar soil grains. In both cases, the interplay of surface energy forces with particle shape effects resulted in even higher shear strength, with predictions similar to the estimates of shear strength for real lunar soil. Once again, the peak strength was dominated by macroscopic cohesion which, on the other hand, was hardly observable at the critical state, confirming the tendency observed from spherical grains. Finally, the practical implications of the above findings were discussed in terms of bearing capacity, trafficability and slope stability on the lunar surface. In particular an analytical approach, based on the bearing capacity problem, was devised to study the performance of a rigid wheel rotating on a lunar terrain and operating under different dynamic conditions.

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Jedenius, Arthur. „Internal Erosion and Dam Stability : Analysis of the internal erosion effects on stability of an embankment dam“. Thesis, Luleå tekniska universitet, Geoteknologi, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-68551.

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Embankment dams encounter several problems in terms of dam safety. One of those problems is called internal erosion. This phenomenon is induced by the movement of fine particles within the dam due to seepage forces. If the dam is not able to self-heal, the eroded zones will increase which will eventually cause the dam to fail. Thus standards have been created by Svensk Energi and summarized in the Swedish dam safety guideline RIDAS 2012. These standards are used as a basic in the risk analysis of existing dams and provide guidelines for proper design of future dams.A dam in Sweden has presented recurring incidents related to internal erosion within the core. The impact of this internal erosion is analysed in this thesis with the use of Finite Element Method/Analysis (FEM/A). FEA models simulate the in situ stresses in the dam and calculate the strength. It also enables the analysis of changing hydraulic conductivity and its effect on the overall effective strength due to changing pore pressure and seepage forces. The analysis using numerical methods was performed in the program PLAXIS2D and SEEP/W while limit equilibrium analysis was done in SLOPE/W.The calculation in PLAXIS2D was performed by using the Mohr-Coulomb constitutive model. The in situ stresses are initially calculated using gravity loading since this is the preferred method on an uneven terrain instead of a K0-calculation. Then, through a set of phases in the program, zones where erosion is assumed to have occurred are changed. These zones have a higher permeability and will thus affect the pore pressures in the dam following Darcy’s law with permeability through a set medium.The increased permeability is set to follow an increased void ratio due to loss of fine material in the core. How this increase of void ratio affects the permeability is investigated through using Ren et al’s (2016) proposed equation for calculating permeability with a set void ratio. Their equation, apart from the usually used Kozeny-Carman equation, considers both effective and ineffective void ratio where the ineffective void ratios refers to the volume of pores that is immobile when flow is considered.The increased flow in the eroded zones of the core did not seem to impact the strength of the dam in much regard. The phreatic surface and thus the pore pressure did not change enough to influence the overall effective strength of the dam. It raises the question if the stability of an earth-rock fill dam will be affected due to increased pore pressure at all due to its draining properties and if it would rather fail due to increased seepage forces.

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Intsiful, Sekyi K. „DEFORMATION-BASED EXCAVATION SUPPORT SYSTEM DESIGN METHOD“. UKnowledge, 2015. http://uknowledge.uky.edu/ce_etds/29.

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Development in urban areas around the world has steadily increased in recent years. This rapid development has not been matched by the ever decreasing open space commonly associated with urban centers. Vertical construction, thus, lends itself a very useful solution to this problem. Deep excavation is often required for urban construction. Unfortunately, the ground movements associated with deep excavation can result in damage to adjacent buildings. Thus, it is critically important to accurately predict the damage potential of nearby deep excavations and designing adequate support systems. A new design method is proposed, as an attempt, to address the problem. The method is semi-empirical and directly links excavation-induced distortions experienced by nearby buildings and the components of the excavation support system. Unlike, the traditional limit equilibrium approach, the method is driven by the distortions in adjacent buildings. It goes further to propose a preliminary cost chart to help designers during the design phase. The benefit is that initial cost is known real time and will help speed up making business decisions. A new design flowchart is proposed to guide the designer through a step-by-step procedure. The method is validated using 2D Plaxis (the finite element program) simulation. Though the nature of deep excavation is three-dimensional, a plane strain condition is valid when the length of the excavation is long. Hence, two-dimensional finite element simulation was considered appropriate for this effort. Five hypothetical cases were compared and the model performed very well. The lack of available literature on this approach made verification difficult. It is hoped that future case histories will be used to ascertain the veracity of the deformation-based design method.

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Skarvelas, Georgios Aristeidis. „Reinforcement and Bonded Block Modelling“. Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-85984.

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The objective of this master’s thesis is to evaluate the use of Bonded Block Modelling (BBM) in 3DEC software combined with hybrid rock bolts, for three different cases. These cases included the laboratory rock bolt case, the shearing case and the blocky rock mass case. 3DEC is a Distinct Element Method (DEM) numerical software which can be used to simulate both continuum and discontinuum media in 3D. The Bonded Block Model in 3DEC can be used to simulate a rock mass as bonded polyhedral elements. The BBM is a relatively new numerical modelling technique. Earlier studies have focused mainly on laboratory test cases and less on field scale studies. The laboratory rock bolt test was introduced by Hoek and the main idea was to describe the way that rock bolts work. Four different rock bolt spacing designs were simulated and one unsupported model, in order to validate Hoek’s results. The diameter of the blocks was 15 cm while the zones were modelled with length of 5 cm. The tunnel on the shearing case was excavated at the depth of 1500 m. For the stress field, the in-situ stresses of Kiirunavaara mine were considered. The tunnel on the blocky case was excavated at the depth of 30 m and a gravitational stress field was assumed. The shearing model as well as the blocky model, were simulated on a quasi-3D model. The zone length for both cases was 0.1 m. In both cases, a discontinuum non-BBM was modelled first and then, a discontinuum BBM with different rock UCS values was simulated. The discontinuum BBM on the shearing case was simulated for rock UCS of 200, 100, and 50 MPa, while on the blocky case, it was simulated for rock UCS of 50 MPa. The Mohr – Coulomb constitutive model was selected for all three modelling cases. The conclusions of this work were the following: – The laboratory rock bolt model validated the results of Hoek. Hoek suggested that rock bolt spacing less than three times the average rock piece diameter would be sufficient to produce positive results. The stabilization of the rock pieces as well as the forming of the compression zone were achieved when this equation was satisfied. The geometry of the stabilized material as well as the compression zone, were also correct. – The discontinuum BBM on the shearing case with intact rock UCS of 200 MPa, produced similar results as the discontinuum non-BBM. This indicates that BBM can be applied for these cases and produce reliable results. The displacement of the fault was expected to be higher than the resulting values. The discontinuum BBM with reduced rock strength (100 MPa and 50 MPa) resulted in rock mass fragmentation. However, the fragmented rock pieces did not detach from the rock mass as the displacement values were not high enough. – The discontinuum BBM on the blocky case with intact rock UCS of 50 MPa, produced similar results as the discontinuum non-BBM. There were two discontinuities that affected the smooth transition of the displacement/stress results on the different blocks. The fragmentation of the rock mass due to the existence of the discontinuities did not produce any further rock mass movements. – The interaction between rock mass and rock bolts was evident in any modelling case. For the laboratory rock bolt model, the hybrid bolts design was vital for producing correct results. For the shearing model, the hybrid bolts were subjected to shearing movements due to fault movements. In the blocky model, the bolts in the roof of the tunnel were subjected to axial displacements, due to the existence of blocks. The recommendations for further work were the following: – The hybrid bolts in the laboratory rock bolt test were pretensioned only in the beginning of the computation phase. In reality, the tensioned bolts act at every moment and not only in the beginning. However, it would be interesting to see if the results are similar with continuously tensioned hybrid bolts. It is anticipated that the constantly tensioned hybrid bolts should be able to keep the compressive zones with high values throughout the whole cycling process. Thus, it is suggested for future modellers that this case could be modelled with continuously tensioned hybrid bolts. – The installation of rock bolts in the shear case as well as in the blocky case, was at the exact same time as the tunnel was excavated. This is not realistic fact because it is impossible to install the rock bolts exactly the same time as the tunnel excavated. Thus, it is suggested that those two cases could be modelled in the future with more focus on the stress relaxation factor.

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Koudela, Pavel. „Stanovení hodnot vstupních parametrů pokročilých materiálových modelů s využitím optimalizačních metod“. Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-372248.

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Choice of the constitutive model and determination of input parameters are necessary for a successful application of numerical methods in geotechnical engineering. Higher complexity of modern constitutive models results in an increase of the number of input parameters and time requirements for their calibration. Optimization methods are a possible solution for this problem. An application in which metaheuristic optimization method Particle swarm optimization (PSO) is involved is presented in this thesis. Critical review and testing of various PSO alternatives was performed in the first part of this thesis. The most efective PSO alternatives were chosen. In the second part connection between PSO algorithm and finite element solver was prepared. Automatization of determination of constitutive models input parameters was performed on three boundary value problems: laboratory test (oedometer), in-situ test (pressuremeter) and geotechical construction (retaining wall). Three types of constitutive models are used. Linear elastic-perfectly plastic Mohr-Coulomb model, elastoplastic non-linear Hardening soil model and Hardening soil - small strain model.

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Bůžková, Eliška. „Zajištění sanační jámy pro ekologické účely“. Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2012. http://www.nusl.cz/ntk/nusl-225487.

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As the trend in environmental care grows, the emphasis on removing the old environmental burdens is bigger. This thesis is dedicated to the case when the soil was contaminated by products of gas industry in the area of Jihomoravská plynárenská, a.s. in Brno - Zábrdovice . The aim of this work is to select the appropriate remediation technology and shoring remediation pit in mentioned locality. Diploma thesis also includes design and assessment of selected construction sheeting calculated by the method of dependent pressures, technology design and implementation of construction drawings.

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Bartolomeu, Daniel. „Análise da vulnerabilidade dos recursos hídricos na região urbana de São Carlos (SP) por vazamentos em postos de combustíveis, utilizando o método GOD e avaliação dos condicionantes geotécnicos“. Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/18/18132/tde-08112012-112827/.

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O constante avanço econômico e tecnológico que estamos vivendo, nos dias de hoje possui como uma das mais marcantes características o aumento na demanda de combustíveis para diversos usos. Fato que pode ser preocupante do ponto de vista ambiental, onde estes combustíveis representam grandes potenciais poluidores. Na área de estudos (região urbana de São Carlos - SP) já existem focos de poluição identificados pela CETESB, onde também ocorrem três importantes aquíferos: Bauru, Guarani (porosos) e Serra Geral (fraturado), estando estes em sessão aflorante (zona de recarga) e em sub-superfície. O mapeamento geológico-geotécnico é uma importante ferramenta, que pode ser empregada como método de diagnóstico fundamentando a análise de vulnerabilidade de contaminação dos recursos hídricos. Com a integração do mapeamento geotécnico e técnicas de caracterização específicas de áreas contaminadas poderemos proceder com uma análise de vulnerabilidade mais consistente. O método GOD, utilizado como parâmetro para a análise de vulnerabilidade, vem sendo muito utilizado tanto no cenário nacional como internacional. Neste trabalho se mostrou eficiente, sendo possível correlacionar as diversas classes de vulnerabilidade com os compartimentos geológico-geotécnicos definidos no mapeamento e com a análise dos condicionantes geotécnicos que podem deflagrar uma contaminação em cada unidade geológico-geotécnica definida.
The constant economic and technological advancement that we are living today has one of the most striking features an increase in fuel demand for different uses. This fact may be worrying the environmental point of view, where these fuels are major potential polluters. In the study area (urban area of Sao Carlos - SP) since there are outbreaks of pollution identified by CETESB, where also there are three major aquifers: Bauru, Guarani (porous) and Serra Geral (fractured), the latter being in session outcropping (zone charge) and sub-surface. The geological-geotechnical mapping is an important tool that can be used as a method of diagnosing the reasons for vulnerability analysis of contamination of water resources. With the integration of geologicalgeotechnical mapping and geotechnical characterization techniques to specific contaminated areas can proceed with a more consistent vulnerability analysis. The GOD method, used as a parameter for the vulnerability analysis, has been widely used in both the national and international scenario. In this work This method was successfully, it is possible to correlate the various classes of vulnerability compartments defined in the geological-geotechnical mapping and analysis of geotechnical conditions which may trigger a contamination in each unit defined.

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Macaro, Giulia. „Distinct element modelling of pipe-soil interaction for offshore pipelines on granular soils“. Thesis, University of Oxford, 2015. http://ora.ox.ac.uk/objects/uuid:cf38c129-502f-4d7d-aa8c-fea5d95ad2d2.

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Offshore on-bottom pipelines are subjected to cycles of thermal and pressure-induced axial expansion, which can cause them to buckle laterally. For an elegant and cost-effective solution, lateral buckling is allowed in a controlled manner. Of the various design parameters, the soil resistance has the greatest associated uncertainty. Previous studies of lateral pipe-soil interaction have used laboratory model tests and continuum-based numerical methods. However, they are economically and computationally expensive, and have mostly been restricted to pipes on undrained clay. To overcome this limitation, this thesis introduces the distinct element method (DEM) as a novel numerical tool for the study of lateral pipe-soil interaction for partially embedded offshore pipelines on sandy seabeds. The DEM directly models the particulate nature of sandy soils, allowing large displacements of discrete bodies and providing insights into the mechanics of the soil at a particle level. Pipe{soil interaction is studied by DEM analyses through four separate research stages: (i) mechanical characterisation of the soil, (ii) specimen preparation and pipeline implementation, (iii) small displacement pipe loading tests and (iv) large displacement pipe loading tests. The soil is modelled as an assembly of spherical particles exchanging contact forces, energy and momentum when they interact. At the microscopic scale, a novel moment-relative rotation contact law is introduced to account for the irregular shape of real sand grains. At a macroscopic scale, the mechanical behaviour of the sand is calibrated using experimental triaxial test data. Additional work includes the numerical preparation of a soil assembly and the implementation of a pipeline object in the open-source DEM code Yade. A novel specimen preparation technique is developed to assemble a homogeneous sample at a desired relative density. The pipeline is implemented as a cylindrical body with a continuously curved surface and a specific mass. Small displacement loading tests are performed, with a segment of the pipeline interacting with a 3D prismatic soil domain, replicating plane strain conditions. The influence of particle size, domain thickness, loading velocity and damping are investigated. The findings provide valuable recommendations for performing DEM simulations of this problem, balancing numerical accuracy and computational effort. Large displacement loading tests are performed to validate the DEM approach and to obtain detailed insights into the nature of the pipe-soil interaction. Monotonic vertical and lateral loading simulations are quantitatively compared with laboratory results. To replicate realistic loading conditions of the pipeline on the seabed, cyclic large displacement tests are also performed. Both the monotonic and the cyclic tests show a good level of agreement with experimental results obtained in previous research. Moreover, the numerical analyses provide insights into the evolution of particle motion and the failure mechanism within the soil.

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Bjureland, William. „On reliability-based design of rock tunnel support“. Licentiate thesis, KTH, Jord- och bergmekanik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-204919.

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Tunneling involves large uncertainties. Since 2009, design of rock tunnels in European countries should be performed in accordance with the Eurocodes. The main principle in the Eurocodes is that it must be shown in all design situations that no relevant limit state is exceeded. This can be achieved with a number of different methods, where the most common one is design by calculation. To account for uncertainties in design, the Eurocode states that design by calculation should primarily be performed using limit state design methods, i.e. the partial factor method or reliability-based methods. The basic principle of the former is that it shall be assured that a structure’s resisting capacity is larger than the load acting on the structure, with high enough probability. Even if this might seem straightforward, the practical application of limit state design to rock tunnel support has only been studied to a limited extent. The aim of this licentiate thesis is to provide a review of the practical applicability of using reliability-based methods and the partial factor method in design of rock tunnel support. The review and the following discussion are based on findings from the cases studied in the appended papers. The discussion focuses on the challenges of applying fixed partial factors, as suggested by Eurocode, in design of rock tunnel support and some of the practical difficulties the engineer is faced with when applying reliability-based methods to design rock tunnel support. The main conclusions are that the partial factor method (as defined in Eurocode) is not suitable to use in design of rock tunnel support, but that reliability-based methods have the potential to account for uncertainties present in design, especially when used within the framework of the observational method. However, gathering of data for statistical quantification of input variables along with clarification of the necessary reliability levels and definition of “failure” are needed.

QC 20170407

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Dubost, Julien. „Variabilité et incertitudes en géotechnique : de leur estimation à leur prise en compte“. Thesis, Bordeaux 1, 2009. http://www.theses.fr/2009BOR13808/document.

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L’évolution actuelle de l’ingénierie géotechnique place la maîtrise des risques d’origine géotechnique au cœur de ses objectifs. On constate aussi que la complexité des projets d’aménagement (à travers les objectifs coûts/délais/performances qui sont recherchés) est croissante et que les terrains choisis pour les recevoir présentent, quant à eux, des conditions géotechniques de plus en plus souvent « difficiles ». Ces conditions défavorables se traduisent par une variabilité forte des propriétés des sols, rendant leur reconnaissance et leur analyse plus complexe. Ce travail de thèse traite de la caractérisation de la variabilité naturelle des sols et des incertitudes liées aux reconnaissances géotechniques dans le but de mieux les prendre en compte dans les dimensionnements des ouvrages. Il se positionne dans le contexte de la maîtrise des risques de projet d’origine géotechnique. Les principaux outils statistiques servant à décrire la dispersion des données et leur structuration spatiale (géostatistique), ainsi que des méthodes probabilistes permettant d’utiliser leur résultats dans des calculs, sont présentés sous l’angle de leur application en géotechnique. La démarche est appliquée à un projet de plate-forme ferroviaire. Cette infrastructure a été implantée sur un site géologiquement et géotechniquement complexe, et présente aujourd’hui des déformations importantes dues aux tassements des sols. Une nouvelle analyse des données géotechniques a donc été entreprise. Elles ont, au préalable, été regroupées dans une base de données qui a facilité leur traitement statistique et géostatistique. Leur variabilité statistique et spatiale a été caractérisée permettant une meilleure compréhension du site. Le modèle géologique et géotechnique ainsi établi a ensuite été utilisé pour calculer les tassements. Une démarche en trois temps est proposée : globale, locale et spatialisée permettant une estimation des tassements et de leur incertitude, respectivement, à l’échelle du site, aux points de sondages, et spatialisée sur la zone d’étude. Les résultats montrent clairement l’intérêt des méthodes statistiques et géostatistiques pour la caractérisation des sites complexes et l’élaboration d’un modèle géologique et géotechnique du site adapté. La démarche d’analyse des tassements proposée met en avant le fait que les incertitudes des paramètres se répercutent sur les résultats des calculs de dimensionnement et expliquent le comportement global de l’infrastructure. Ces résultats peuvent se traduire sous forme d’une probabilité de ruine qui peut ensuite être utilisée dans un processus de prise de décision et de management des risques. D’une manière plus large, ce travail de thèse constitue une contribution à l’élaboration et l’analyse des campagnes de reconnaissances géotechniques, en ayant le souci d’identifier, d’évaluer et de prendre en compte la variabilité et les incertitudes des données lors des différentes phases du projet pour permettre une meilleure maîtrise du risque d’origine géotechnique
The current evolution of the geotechnical engineering places the risk management of geotechnical origin in the heart of its objectives. We also notice that the complexity of the projects of development (through the objectives costs/deadline/performances which are sought) is increasing and that soil chosen to receive them present unusual geotechnical conditions. These unfavourable conditions usually mean a strong variability of the soil properties, which induces soil investigation and data analysis more difficult. This work of thesis deals with the characterization of the natural variability of soils and with the uncertainties dues to geotechnical investigations, with the aim to better take them into account in geotechnical engineering project. This work takes place in the context of the management of the risk of project with geotechnical origin. The main statistical tools used for describe the scattering of the data and their spatial variability (geostatistic), as well as the probabilistic methods enabling to use their results in calculations, are presented under the view of their application in geotechnical design. The approach is applied to a project of railway platform. This infrastructure was located on a site where the geology and the geotechnical conditions are complex, and which present important deformations due to the soil settlements. A new analysis of geotechnical data was started again. First, geotechnical data were included in a database in order to ease their statistical and geostatistical treatment. Their statistical and spatial variability were characterized allowing a better understanding of the site. The geologic and geotechnical model so established was then used to assess the settlement effects. An analysis in three levels is proposed: global, local and spatial, which give means to estimate the settlement values and its uncertainty, respectively, on the scale of the site, on the boring points, and on zone of study according to the spatial connectivity of soil properties. The results clearly show the interest of statistical and geostatiscal methods in characterizing complex sites and in the elaboration of a relevant geologic and geotechnical model. The settlement analysis proposed highlight that the parameter uncertainties are of first importance on the design calculations and explain the global behaviour of the infrastructure. These results can be translated in the form of a reliabilitry analysis which can be then used in a process of decision-making and risk management. In a wider way, this work of thesis contributes toward the elaboration and the analysis of the geotechnical investigations, with the aim to identify, to estimate and to take into account the variability and the uncertainties of the data during the various stages of the project. It leads to better control of the risk of geotechnical origin

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Salloum, Nancy. „Evaluation de la variabilité spatiale des paramètres géotechnique du sol à partir de mesures géophysiques : application à la plaine alluviale de Nahr-Beyrouth (Liban)“. Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAU014/document.

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La variabilité spatiale des formations géologiques rend difficile la détermination des paramètres géotechniques nécessaires pour l'évaluation des aléas naturels (sismiques et gravitaires). Les méthodes d'imagerie géophysique, non-destructives et rapides, sont de plus en plus utilisées pour la reconnaissance de telles structures hétérogènes. Une campagne d'essais géophysiques et géotechniques a été réalisée dans la plaine alluviale de Beyrouth (Liban), ville soumise à un fort risque sismique, en vue de caractériser la variabilité des couches alluviales. Les résultats combinés ont permis de caractériser la structure 3D du site et de détecter la présence d'une couche d'argile molle, peu profonde et d'épaisseur variable. Cette couche de faible compacité, qui a rendu complexe l'interprétation des courbes de dispersion des ondes de surface, a une influence importante sur la réponse sismique du site. Les incertitudes reliées à la variabilité spatiale des propriétés géotechnique (N60) et géophysiques (Vs, ρ) ont pu être quantifiées au sein des couches rencontrées et les fonctions de distribution de ces paramètres ont été déterminées dans chaque couche à partir de ces essais, à la fois verticalement et horizontalement. Les valeurs de distance d'autocorrélation verticale (Vs, N60) et horizontale (ρ) obtenues ainsi que les valeurs de coefficient de variation se situent dans la gamme de valeurs trouvées dans la littérature. La réponse dynamique (amplification spectrale) de la plaine alluviale de Beyrouth a été simulée avec des modèles probabilistes unidimensionnels, et l'effet des trois paramètres statistiques (loi d'autocorrélation, distance d'autocorrélation et coefficient de variation) décrivant les variabilités des propriétés élastiques du sol (Vs) a été quantifié. Pour obtenir des réponses sismiques réalistes, un critère de sélection des profils Vs générés de façon probabiliste a été introduit afin de ne retenir que les profils compatibles (dans une gamme d'incertitude) avec la courbe de dispersion établie. Les modélisations probabilistes ont montré des différences significatives par rapport aux modélisations déterministes. Le principal paramètre probabiliste contrôlant l'amplification spectrale est le coefficient de variation, suivi de la distance d'autocorrélation, alors que le type de loi a peu d'influence. Enfin, nous avons vu que l'activité humaine peut avoir une influence significative sur l'application des méthodes géophysiques en site urbain. La compréhension d'un milieu complexe dans ce contexte nécessite de combiner toutes les méthodes géotechniques et géophysiques d'investigation afin d'obtenir un modèle robuste 2D/3D de la structure du sol
The spatial variability of geological formations makes it difficult to determine the geotechnical parameters necessary for the evaluation of natural hazards (seismic and gravity). The geophysical imaging methods, non-destructive and fast, are now increasingly used for heterogeneous structures of sub-surface recognition. Geophysical and geotechnical tests were carried out in the alluvial plain of Beirut (Lebanon), city with high seismic risk, to characterize the variability in the alluvial layers. Analyses of these tests were used to characterize the 3D structure of the site and to detect the presence of a shallow soft clay layer of variable thickness. This layer of low compactness, which made the interpretation of dispersion curves of surface waves complex, could be of prime importance for seismic response of the site. Using all the collected data, the uncertainties related to the spatial variability of geotechnical (N60) and geophysical (Vs, ρ) properties of soil were quantified in the layers encountered and the distribution functions of these parameters were determined in each layer, in both directions (vertical and horizontal). The autocorrelation distance in the vertical (Vs, N60) and horizontal (ρ) directions and the coefficient of variation are within the range of values founded in the literature. The dynamic response (spectral amplification) of the alluvial plain of Beirut was modeled by one dimensional probabilistic model and we quantified the effect of the three statistical parameters (autocorrelation function, autocorrelation distance and coefficient of variation) describing the elastic variability properties of soil (Vs). To obtain realistic seismic responses, we proposed a probabilistic (Vs) profile selection criteria in order to retain only compatible profiles (in a range of uncertainty) with the obtained dispersion curve. Probabilistic modeling showed significant differences from the deterministic modeling. It appeared that the main factor controlling probabilistic spectral amplification is the coefficient of variation (COVVs) followed by the autocorrelation distance, while the type of autocorrelation function has little influence. Finally, Human activity was also found to have a significant influence on the application of geophysical prospecting at this urban site. This case illustrates the need of combining investigation methods in order to understand the geophysical measurements in a complex medium and to reach a robust 2D/3D model

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Hazell, Edmund. „Numerical and experimental studies of shallow cone penetration in clay“. Thesis, University of Oxford, 2008. http://ora.ox.ac.uk/objects/uuid:6b5380f1-2d02-4da0-92e0-ae83ad5c4698.

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The fall-cone test is widely used in geotechnical practice to obtain rapid estimates of the undrained shear strength of cohesive soil, and as an index test to determine the liquid limit. This thesis is concerned with numerical modelling of the penetration of solids by conical indenters, and with interpretation of the numerical results in the context of the fall-cone test. Experimental studies of shallow cone penetration in clay are also reported, with the aim of verifying the numerical predictions. The practical significance of the results, in terms of the interpretation of fall-cone test results, is assessed. Results are reported from finite element analyses with the commercial codes ELFEN and Abaqus, in which an explicit dynamic approach was adopted for analysis of continuous cone indentation. Quasi-static analyses using an elastoplastic Tresca material model are used to obtain bearing capacity factors for shallow cone penetration, taking account of the material displaced, for various cone apex angles and adhesion factors. Further analyses are reported in which a simple extension of the Tresca material model, implemented as a user-defined material subroutine for Abaqus, is used to simulate viscous rate effects (known to be important in cohesive soils). Some analyses with the rate-dependent model are displacement-controlled, while others model the effect of rate-dependence on the dynamics of freefall cone indentation tests. Laboratory measurements of the forces required to indent clay samples in the laboratory are reported. Results from displacement-controlled tests with imposed step-changes in cone speed, and from freefall tests, confirm that the numerical rate-dependent strength model represents the observed behaviour well. Some results from experiments to observe plastic flow around conical indenters are also presented. Finally, additional numerical analyses are presented in which a critical state model of clay plasticity is used to study the variation of effective stress, strain and pore pressure around cones in indentation tests at various speeds.

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Čechová, Simona. „Vyhodnocení zatěžovacích zkoušek pilot z tryskové injektáže“. Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2021. http://www.nusl.cz/ntk/nusl-433418.

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The master thesis consists of a theoretical part and a practical part. In the theoretical part jet-grouting technology is described briefly. Mechanical properties of jet-grouted piles were characterized. Various estimation methods of ultimate pile bearing capacity are described in this thesis – analytical calculation of ultimate bearing capacity for bored piles and estimation of ultimate pile bearing capacity by analysis of load-displacement curve defined by CHIN (1970; 1972). Load transfer method for piles and hyperbolic load-transfer curve are introduced. As a part of the load-trasfer method analysis, a method of estimating ultimate pile shaft friction called beta method is defined. In the practical part were evaluated several static load tests of jet-grouted piles and were constructed their load-displacemnt curves. Then reverse analysis of the results from static load tests was performed using load-transfer method. Then ultimate pile bearing capacity was estimated using analytical calculation of pile bearing capacity for bored piles and using analysis of load-displacement curve with method by CHIN (1970; 1972). By evaluation of load transfer method and beta method ultimate shaft resistence for each pile was estimated. Results and load-displacement curves were compared.

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Gonçalves, Julio Fernandes. „Estudo numérico do comportamento de muros de solo reforçado com geossintético“. Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/3/3145/tde-18012017-163942/.

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O uso de reforços geossintéticos tem se apresentado como uma solução eficiente que permite reduzir os custos de implantação de estruturas de contenção. Seu comportamento pode ser estudado com a utilização de softwares de elementos finitos na intenção de obter configurações ainda mais econômicas. Neste trabalho foram simulados muros de solo reforçados com geossintéticos (MSRG) pelo método dos elementos finitos (software Plaxis 8.2), analisando-se como parâmetro o deslocamento máximo da face dos muros e a máxima força mobilizada no reforço. Inicialmente, desenvolveu-se e calibrou-se um modelo numérico a partir de um modelo físico construído e monitorado encontrado na literatura. Em seguida construiu-se um modelo numérico de MSRG hipotético e realizaram-se estudos paramétricos com as variáveis: tipo de solo, priorizando-se solos finos tropicais; rigidez e espaçamento do reforço; e inclinação e altura do muro. Os resultados corroboraram a bem sucedida prática nacional de construção de muros reforçados com solos finos tropicais, sendo que a coesão se mostrou um parâmetro importante no comportamento de MSRG construídos com solos finos.
The use of geosynthetic reinforcements is an efficient solution that reduces the costs of implantation of containment structures. Their behavior can be studied by the use of finite element software, with the goal to obtain more economical configurations. In this study, geosynthetic reinforced retaining walls (MSRG) were simulated by the finite element method (software Plaxis 8.2), analyzing as a parameter the maximum face displacement and the maximum force mobilized in the reinforcement. Initially, a numeric model was developed and calibrated from a constructed and monitored physical model of the literature. After, a numerical model of hypothetical MSRG was constructed and parametric studies were done with the following variables: soil type, prioritizing tropical fine soils; reinforcement stiffness and spacing, and slope and height of the wall. The results corroborated the successful brazilian practice at the building reinforced MSRG with tropical fine soils, due cohesion being an important parameter in the behavior of MSRGs constructed with fine soils.

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