Tesis sobre el tema "Bender element"
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Johnson, Sean (Sean Michael). "Modeling a bender element test using Abaqus Finite Element Program". Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/64573.
Texto completoCataloged from PDF version of thesis.
Includes bibliographical references (p. 253-255).
Finite Element Methods hold promise for modeling the behavior of an unsaturated soil specimen subjected to bender element agitation. The immediate objective of this research project is to reproduce a bender element test using Abaqus Finite Element Software assuming elastic and isotropic conditions. Extensive compressions were made of bender element testing of unsaturated Ticino Sand specimens uniaxially compressed and the Abaqus Finite Element Method program simulation. The research determined that the mesh resolution of a numerical analysis are optimal at a resolution of a twentieth of the shear wavelength and the integration time step has a negligible effect on the observed wave velocity. Moreover, it is possible to reproduce an uniaxially stressed bender element experiments of unsaturated Ticino sand in an Abaqus Finite Element Method program with relatively minimal error of the body wave velocity measurements if the source receiver distance is beyond two shear wavelengths and the reflected signals from the boundaries are suppressed.
by Sean Johnson.
S.M.
Lo, Kai Fung. "Small-strain shear modulus and damping ratio determination by bender element /". View abstract or full-text, 2005. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202005%20LOK.
Texto completoKnutsen, Mirjam. "On Determination of Gmax by Bender Element and Cross-Hole Testing". Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for bygg, anlegg og transport, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-27232.
Texto completoHasan, Ahmed M. "Small strain elastic behaviour of unsaturated soil investigated by bender/extender element testing". Thesis, University of Glasgow, 2016. http://theses.gla.ac.uk/7492/.
Texto completoLi, Bo. "EFFECT OF FABRIC ANISOTROPY ON THE DYNAMIC MECHANICAL BEHAVIOR OF GRANULAR MATERIALS". Case Western Reserve University School of Graduate Studies / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=case1291071699.
Texto completoAraya, Contreras Sofía Esperanza. "Medición de parámetros dinámicos de arena con finos mediante columna resonante". Tesis, Universidad de Chile, 2017. http://repositorio.uchile.cl/handle/2250/145564.
Texto completoChile es uno de los países más sísmicos del mundo; escenario de grandes terremotos en el pasado y con toda seguridad, en el futuro. En particular, los suelos son afectados por movimientos sísmicos. Por lo que es importante conocer las propiedades dinámicas del suelo (rigidez máxima Gmax , curvas de degradación G/Gmax y el amortiguamiento D ) para el correcto diseño de proyectos de ingeniería. Existen distintos ensayos para medir parámetros dinámicos del suelo, sometiéndolos a pequeñas y grandes deformaciones. El módulo de corte G y el amortiguamiento D se obtienen con ensayos de laboratorio y terreno. En particular, en laboratorio, uno de los ensayos que cubre un mayor rango de deformación es el de columna resonante (D4015-15, 2016). Este trabajo de título consistió en realizar ensayos de columna resonante en arenas de relave del muro del tranque El Torito (Mina de cobre El Soldado). Los ensayos fueron hechos con probetas de arena preparadas entre 35% y 85% de densidad relativa, y confinamientos que variaron entre 1 [kg/cm2] y 4 [kg/cm2]. Los resultados obtenidos se compararon con los obtenidos en el equipo Bender Element. Los Gmax dieron entre 40 y 180 [MPa]. Los ensayos de columna resonante entregaron rigideces máximas moderadamente mayores (5%) a los de Bender Element. Esto debido posiblemente a que las probetas del primer ensayo se vieron menos alteradas en su confección. Todas las curvas de degradación del módulo de corte G/Gmax y amortiguamiento D varían respecto a su deformación al corte con una tendencia que concuerda con lo observado en la literatura. A mayor confinamiento, las muestras tienen mayor rigidez inicial, mayor G/Gmax y menor amortiguamiento. A mayor índice de vacíos, las probetas tienen menor rigidez inicial y mayor G/Gmax , el amortiguamiento no tiene mayor variación respecto este parámetro. El comportamiento de las muestras al 5% de saturación es similar al de las muestras saturadas.
Karam, Jean-Paul. "Etude de la rhéologie des loess du Nord de la France - Application à l'évaluation de leur risque de liquéfaction". Phd thesis, Ecole des Ponts ParisTech, 2006. http://pastel.archives-ouvertes.fr/pastel-00002185.
Texto completoRizzi, Vera Federica. "Studio della riattivazione della frana di Montevecchio (FC) mediante misure in sito e in laboratorio". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amslaurea.unibo.it/13411/.
Texto completoMohsin, AKM. "AUTOMATED Gmax MEASUREMENT TO EXPLORE DEGRADATION OF ARTIFICIALLY CEMENTED CARBONATE SAND". Thesis, The University of Sydney, 2008. http://hdl.handle.net/2123/5003.
Texto completoMohsin, AKM. "AUTOMATED Gmax MEASUREMENT TO EXPLORE DEGRADATION OF ARTIFICIALLY CEMENTED CARBONATE SAND". University of Sydney, 2008. http://hdl.handle.net/2123/5003.
Texto completoSoil Stiffness is an important parameter for any geotechnical engineering design. In laboratory tests it can be derived from stress-strain curves or from dynamic measurement based on wave propagation theory. The second method is a more accurate and direct method for measuring stiffness at very small strains. Until now dynamic measurements have usually been obtained manually from the triaxial test. Attempts have been made to automate the procedure but have apparently failed due to the high level of variability in dynamic measurements. Moreover, triaxial tests of soil can be very lengthy and manual dynamic measurements can be very tedious and impractical for long stress-path tests. In this research a computer program has been developed to automate the stiffness measurement (using bender elements) based on the cross- correlation technique. In this method the program records all the peaks and corresponding arrival times in the cross-correlation signal during the test. The stiffness is calculated and displayed on the screen continuously. The Bender Element enabled to get the small strain shear modulus. An arbitrary “Chirp” waveform of 4 kHz frequency was used for this purpose. Subsequently Bender Element test results were checked by ‘Sine’ waveforms of frequencies 5kHz to 20kHz, as well as by manual inspection of the arrival time. This thesis discusses the method and some of the difficulties in truly automating the process. Finally some results from a number of stress path tests on uncemented and cemented calcareous sediments are presented. Bender elements have been used by many researchers to determine the shear modulus at small strain. Most previous studies have used visual observation of arrival time, which is time consuming and often requires some judgement from the operator. This thesis will describe the use of cross-correlation as a method for automation of Gmax measurement. Cross-correlation has been claimed to be unreliable in the past. However, it will be shown that provided several peaks in the cross-correlation signal are monitored it is possible to follow the variation of Gmax throughout consolidation and shearing. The measurement can be made at regular intervals within the software controlling a stress-path apparatus. Details of the apparatus used and practical considerations including selection of waveform and frequency are discussed. A series of drained cyclic triaxial tests was carried out on artificially cemented and uncemented calcareous soil of dry unit weights 13, 15, and 17 kN/m3 and sheared with constant effective confining stress 300 kPa. Gypsum cement contents of 10%, 20% and 30% of the dry soil weight were used. In addition a series of stress path tests were performed on Toyuora sand samples. Results will be presented for two uncemented and one cemented sand. In addition to the bender elements, all tests had internal instrumentation to monitor axial and lateral strains. Results will be presented for Toyura sand to show that the measurements are consistent with those obtained by other methods. Results will also be presented for carbonate sand subjected to a wide range of stress paths. Finally, results will be presented for the carbonate sand cemented with gypsum. The degradation of Gmax of the cemented soil subjected to variety of monotonic and cyclic stress-paths is presented. Analysis of the results includes assessment of the factors influencing Gmax for uncemented sand. Preliminary analysis indicates that in order of importance these are the mean effective stress, the stress history, void ratio and stress ratio. For cemented sand, Gmax is initially constant and independent of stress path. After yielding the modulus degrades, becoming increasingly stress level dependent and eventually approaches the value for uncemented sand. Factors influencing the rate of degradation are discussed. For the Toyuora sand samples the effects of end restraint on the stress-strain response at small strains were investigated. The conventional method of mounting triaxial specimen has the effect of introducing friction between sample and end platen during a compression test. This inevitably restricts free lateral movement of the specimen ends. Frictional restraint at the sample ends causes the formation of 'dead zones' adjacent to the platens, resulting in non-uniform distribution of stress and strain (and of pore pressure if undrained). On the other hand the specimen with 'free' ends maintain an approximate cylindrical shape instead of barrelling when subjected to compression, resulting in a more uniform stress distribution.
Rio, Joao Filipe Meneses Espinheira. "Advances in laboratory geophysics using bender elements". Thesis, University College London (University of London), 2006. http://discovery.ucl.ac.uk/1348997/.
Texto completoBate, Bate. "Engineering behavior of fine-grained soils modified with a controlled organic phase". Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/39627.
Texto completoFu, Lei. "Application of Piezoelectric Sensors in Soil Property Determination". Case Western Reserve University School of Graduate Studies / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=case1089850793.
Texto completoSharifipour, Mohammad. "Caractérisation des sols par propagation d'ondes analyse critique de la technique des bender extender elements". Nantes, 2006. http://archive.bu.univ-nantes.fr/pollux/show.action?id=1d7aacac-7a0c-4cdd-bd26-c0cddb4cf572.
Texto completoThe research work deals with the analysis of the « bender-extender elements » technique, used worldwide for the identification of elastic properties in the very small strains domain ( < 10-5 to 10-6). This technique consists in propagating both compression (P) and shear waves (S) through a soil sample. The relevance of the standard interpretation method (called time analysis), which was assessed during an international round robin test, is first discussed. Then, alternative frequency analysis is presented and also criticized. This discussion is supported by an extensive experimental program in dry granular materials (glass beads, lead beads, Toyoura sand, Hostun sand). Both the time and frequency analysis present some subjectivity about the identification of the wave time-of-flight but leads to a similar solution provided that some precautions are taken into account. The frequency analysis highlights a specific evolution of the peak frequency of the output signals versus the applied stress. This evolution is put in parallel with the evolution of the wave velocities. Considering many approaches, we show that the output signals result from the dynamic behaviour of the piezo-ceramics sensors embedded into a constrained soil. Finally, the study is extended to the case of saturated soils and partially saturated soils
Georgetti, Giovana Bizão. "Deformabilidade de um solo laterítico não saturado". Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/18/18132/tde-20032015-103943/.
Texto completoStiffness is a fundamental property in geotechnical design. The fact that strains are in the smallto- very small strain range in several engineering works and the limitations of testing techniques in measuring such level of strains led to the development of dynamic techniques, such as resonant column and bender elements. Specifically, the bender elements technique has been increasingly used due to the simplicity in performing tests and computing the maximum shear modulus of the soil. Several studies have been carried out to assess stiffness properties of dry or saturated soils via bender elements, however, studies of this nature are still relatively scarce in unsaturated soils. This research investigated the influence of some variables, like suction and confining stress, on the stiffness of a lateritic unsaturated soil, typical of São Paulo State, via bender elements, resonant column and triaxial compression tests with local gauges. Furthermore, aiming at a more complete characterization of this soil, triaxial compression tests were performed in order to quantify its shear strength. Results from these tests suggested the occurrence of strain hardening on undisturbed specimens, and a planar shear strength envelope was used to represent the compacted sample data. Regarding soil stiffness, results indicated that it increases with a reduction in the compaction moisture content or an increase in isotropic confining stress or suction. Data from bender elements tests were nicely represented by a power function when maximum shear modulus and suction were normalized by the net confining stress. Results of unsaturated compacted soil obtained from bender elements and resonant column tests were compared and slightly larger shear wave velocities were noticed in bender elements tests, which were attributed to the larger testing frequencies used in these tests.
Bender, Amelie [Verfasser]. "Zustandsüberwachung zur Prognose der Restlebensdauer von Gummi-Metall-Elementen unter Berücksichtigung systembasierter Unsicherheiten / Amelie Bender". Paderborn : Universitätsbibliothek, 2021. http://d-nb.info/1226217370/34.
Texto completoBortolotto, Marina Schnaider. "Bender elements, ultrasonic pulse velocity, and local gauges for the analysis of stiffness degradation of an artificially cemented soil". reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2017. http://hdl.handle.net/10183/172327.
Texto completoStiffness at small strains and its respective degradation are crucial information to determine more precise design parameters. Despite their importance, these properties are not usually investigated. Thus, the objective of the present work was to study the stiffness degradation of artificially cemented Osorio sand by means of different laboratory methods. The choice for a cemented material was based on environmental, economic, and technical appeals. The present study also aimed to develop and validate a Bender Elements (BE) system that can provide reliable results in the evaluation of soil degradation. BE pairs were built for bench and triaxial tests. In addition, a signal amplifier, as well as scripts were specially developed for the interpretation of data in the time domain. Increase in stiffness during the curing process was evaluated by shear wave velocity measured by BE and an ultrasonic pulse wave velocity (UPV) equipment under atmospheric pressure conditions. Stiffness degradation tests were conducted in a specially modified triaxial chamber for BE installation After seven days of atmospheric curing, specimens were sheared in the modified triaxial equipment, while stiffness changes were obtained by BE tests and internal instrumentation. The results showed that the developed BE system was capable of successfully evaluating the studied soil. The comparison between BE and UPV results was not conclusive regarding soil dependence on frequency. Shear module degradation obtained with the two methodologies presented an adequate agreement for the specimen with the smaller amount of cement. Shear moduli obtained with BE were slightly larger than those obtained with internal measurements. Also, BE results interpretation in the time domain for cemented specimens, especially in the triaxial tests, was difficult to perform, reinforcing the need to combine different interpretation methods when BE are used.
Santos, Roberto Aguiar dos. "Comportamento anisotrópico de um solo laterítico compactado". Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/18/18132/tde-22032016-104302/.
Texto completoCompacted embankments can have anisotropic behavior, depending on several factors, including the compaction water content. The aim of this study was to investigate some aspects regarding the inherent anisotropy of a lateritic soil, caused by the compaction process. After performing the geotechnical, mineralogical and microstructural characterization, properties of shear strength, hydraulic conductivity, compressibility and deformability were investigated. This soil this soil was classified as lateritic sand. The grainsize distribution curve indicates 12% the fine particle aggregation. The methodology developed in order to correct the increase in dry density of the lower layers, generated by the compression process, was effective. From the compaction curve, representative samples corresponding to the three compaction water content conditions, representing the dry side, the optimal water content and the wet side were considered. Specimens were trimmed parallel and orthogonally to the compaction layers. The porosimetry tests showed a bimodal behavior in the pore size distribution and also that the compaction water content did not influence the size of the micropores. For the compacted soil sample corresponding to the dry side and optimum water content, the shear strength corresponding to the orthogonal direction was higher than that corresponding to the parallel direction to the compaction layers. However, they were almost equal for both the orthogonal and the parallel directions to the compaction layers. This behavior is due to the higher capacity of the soil at a given moisture content, to absorb the energy applied and distribute it in parallel and orthogonal direction. The analysis the values of maximum shear modulus of the material showed that increasing compaction water content reduces the anisotropy degree. Among the investigated properties, the hydraulic conductivity anisotropy of the samples corresponding to the wet branch was the most pronounced, showing permeability eight times higher in the vertical direction than that in the horizontal direction. Finally, the discussions and analyzes presented in this study showed that the degree of anisotropy directly depends on the compaction water content and decreases with increase confining stress applied to the soil specimens.
Fernandes, Jeferson Brito [UNESP]. "Resistência e deformabilidade de um solo não saturado a partir de ensaios triaxiais". Universidade Estadual Paulista (UNESP), 2016. http://hdl.handle.net/11449/143473.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
O principal objetivo deste trabalho é estudar o comportamento geomecânico de um solo tropical não saturado, a fim de avaliar o efeito da sucção nos resultados de ensaios de resistência e de deformabilidade. As amostras são classificadas como areia fina pouco argilosa, de composição granulométrica semelhante nas três profundidades estudadas (1,5, 3,0 e 5,0 m). Além desses solos apresentarem praticamente nenhuma plasticidade, as curvas de retenção da água mostraram que eles têm valores de entrada de ar próximo a 2 kPa e zonas de dessaturação verticalizadas. As envoltórias de resistência determinadas a partir de ensaios triaxiais saturados e não saturados mostraram que o acréscimo no ângulo de atrito e na coesão é devido principalmente à sucção e às características físicas do solo de cada profundidade. Verificou-se que a previsão da resistência não saturada pode ser feita empregando uma função hiperbólica em conjunto com uma função da porosidade quando a razão entre os ângulos de atrito ϕb/ϕ’ no estado saturado é menor que a unidade. Estudou-se também a variação do módulo de cisalhamento máximo (G0) para diferentes condições de sucção, confinamento e de carregamento. A determinação de G0 desses solos foi feita por meio de ensaios triaxiais equipados com transdutores de flexão, chamados de bender elements. Esses resultados mostraram que a variação de G0 em função do estado de tensões e de deformações pode ser adequadamente representada por modelos matemáticos que levam em consideração, além do estado de tensões, o efeito das variações na sucção e na porosidade. Por meio dos dados experimentais obtidos, verificou-se ainda que a compressibilidade desses solos pode ser inserida como variável independente no modelo que considera o efeito da porosidade nas variações de G0.
The objective of this work is to study the geomechanical behavior of a tropical unsaturated soil in order to evaluate the influence of the soil suction on shear strength and deformability test data. The soil samples are classified as clayed fine sand with similar grain size constitution in the three studied depths (1.5, 3.0 and 5.0 m). Besides these soils have almost no plasticity, the water retention curves indicated that these soils present air entry value near to 2 kPa and a vertical desaturation zone. Shear strength envelopes determined via saturated and unsaturated triaxial tests showed that the increase in friction angle and cohesion is mainly due to the suction and to the soil physical characteristics at each depth. When the saturated friction angle ratio (ϕb/ϕ’) is less than one, the unsaturated shear strength prediction can be made using a hyperbolic function together with a function of porosity. The variation of the maximum shear modulus (G0) at different conditions of suction, liquid confining pressure and loading are also studied. The G0 values were determined for these soils in triaxial tests equipped with bender elements. These results indicated that the variation of G0 as a function of the stress and strain state can be properly represented by mathematical models, which take into account the effect of the suction and porosity variation besides the stress state. It was also found by means of the experimental data that the compressibility of these soils can be plugged as an independent variable in a model which considers the influence of soil porosity in the G0 variations.
Wehlack, Veronika [Verfasser], Klaus [Akademischer Betreuer] Bengler, Angelika [Gutachter] Bullinger-Hoffmann y Klaus [Gutachter] Bengler. "Automated Driving: Development of a Drowsiness Management Concept and Evaluation of Related Key Elements / Veronika Wehlack ; Gutachter: Angelika Bullinger-Hoffmann, Klaus Bengler ; Betreuer: Klaus Bengler". München : Universitätsbibliothek der TU München, 2020. http://d-nb.info/1206337621/34.
Texto completoBendel, Verena [Verfasser], Andreas [Akademischer Betreuer] Pack y Bent T. [Akademischer Betreuer] Hansen. "Volatilitätskontrollierte Fraktionierung refraktär-lithophiler Elemente in Meteoriten und der Erde / Verena Bendel. Gutachter: Andreas Pack ; Bent T. Hansen. Betreuer: Andreas Pack". Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2014. http://d-nb.info/1055814582/34.
Texto completoSpencer, Laura Marie. "Evaluation of sand treated with colloidal silica gel". Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/37131.
Texto completoBedin, Jucélia. "Estudo do comportamento geomecânico de resíduos de mineração". reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2010. http://hdl.handle.net/10183/26869.
Texto completoProduction and deposition of mining tailings is a problem confronting geotechnical engineers given the dimension of tailings deposits and environmental risks. The direct launching of tailings in reservoirs contained by dikes consists in a common type of waste disposal. These dikes can be constructed by successive upstream embankments, a relatively simple and economical process adopted in some countries. Although it is a low cost process, the upstream embankment is an operation of great risk, especially because tailings are susceptible to liquefaction and also because the stability of the dams can be threatened by excess of pore pressures generated inside the deposit during construction. To meet design requirements of disposal of residues it is therefore essential to understand the behavior of these materials. Tailings show a considerable variability in their physical, chemical and mineral characteristics that confer a distinct behavior to the geo-materials usually found in natural deposits. The present work gives emphasis to gold and bauxite tailings that encompass substantial economic and environmental interest in Brazil. In the thesis, an extensive laboratory geotechnical investigation program is carried out in an attempt to characterize these residues and to establish design constituent parameters. For comparative purposes an inert silty material is also tested. Compressibility and hydraulic conductivity were measured in oedometer tests performed at constant load and constant hydraulic gradient tests. Triaxial tests were carried out at high stress levels and different stress paths in order to establish the position and shape of the critical state line. In addition measured with Bender Elements are evaluated. The results between the oedometer consolidation (OCL), isotropic consolidation (ICL) and critical sate (CSL) lines allowed the static liquefaction response to be directly assessed. In a e-log (p’) space, the onset of a meta-stable behaviour significantly changes the slope of the CSL relative to both ICL and OCL. The same change in slope is observed on both the state parameter and the small strain shear modulus measured by bender elements when plotted against mean stress. Based on these evidences it is advocated that the CSL of the tailing is highly non-linear in nature, which lead to three distinct soil responses: a stable response when OCL, ICL and CSL exhibit similar slopes, a meta-stable beahaviour at lower stress leading to liquefaction and a crushable response for higher mean stresses. Advanced research on tailings from mining industries with due recognition of the phenomena of liquefaction may prevent dam failure, and consequently may prevent major environmental disasters.
Aris, Mohamed. "Investigations expérimentales des effets de la microstructure sur le comportement des milieux granulaires et sur l'instabilité de liquéfaction". Thesis, Aix-Marseille, 2012. http://www.theses.fr/2012AIXM4018.
Texto completoThis work aims to achieve a better experimental characterization of the undrained behavior of the Hostun HN31 sand at the local scale, depending on the different procedures used for sample reconstitution. We particularly highlight the influence of the microstructure on the mechanical behavior of sand especially in relation to liquefaction instability. The key point of this work consists of the use of piezoelectric transducers to measure shear wave velocities within triaxial sand specimens. These specimens have been prepared by different methods, namely: moist tamping, dry pluviation and water pluviation. The obtained results highlight the considerable influence of the deposition mode on the mechanical behavior of sand. They show that for the same initial density, and at the same confining pressure, the mechanical behavior is very different from the three preparation methods. Furthermore, the values of shear wave velocity are different from one deposition mode to another. Concerning the anisotropy, the material prepared by moist tamping presents an inherent degree of anisotropy, which it is however minimal. On the other hand, dry pluviation and water pluviation induce more isotropic initial structures. Moreover, the initial anisotropy is less important than the anisotropy induced by loading. These experimental results indicate that the initial state of a granular medium can not be described by only couple of scalar variables of initial density and confining pressure: a variable that can reflect the initial microstructure and an evolution law of this variable are necessary to model the experimental observations
Floss, Márcio Felipe. "Parâmetros de controle da resistência e rigidez de solos granulares artificialmente cimentados". reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2012. http://hdl.handle.net/10183/75906.
Texto completoThe soil cement technique itself is an effective tool in the improvement of different soils, adapting them to the needs of geotechnical engineering. Such treatment of the soils might be used in the construction of road subgrades, railway platform subgrades, support layers for shallow foundations, in the encapsulation of contaminated soils in liquefaction prevention of loose granular soils and in barriers for containment of contamination. Thus, this study aimed at measuring the influence of the amount of cement and porosity on the mechanical behavior of granular soils – cement mixtures. Thus, unconfined compression, Brazilian tensile, bender elements and triaxial tests were carried out in order to obtain a dosage methodology for granular soils treated with cement. To this end, an artificial sand-gravel soil, a fine sand soil of basaltic origin, a fine sand soil of granitic origin and lastly, a coarse sandy soil, also of granitic origin were used. Early strength Portland cement was used as cementing agent, as well as distilled water. Cylindrical specimens were cast with different levels of cement and porosity. Strength tests were performed after 7 days curing in an environment with controlled temperature and humidity. Assays were performed using bender elements throughout the curing time, up to 7 days. Finally, a full analysis was performed using data obtained in present work, together with results of other granular soils treated with cement obtained through a literature review, in order to improve understanding of soil cement technique and enhance a dosage methodology of soil cement.
Hoch, Bruna Zakharia. "Misturas de chalk com cimento : estudo da rigidez, resistência e durabilidade". reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2017. http://hdl.handle.net/10183/169813.
Texto completoChalk is a limestone formed by calcite, with up to 95% of calcium carbonate content. It can be found in Western Europe and it covers about 15% of the area of the United Kingdom. Many constructions and infrastructure works are carried out on chalk, and unpredictable situations still happen due to the lack of knowledge of its geotechnical behavior. Undisturbed, chalk is a weak rock that remains stable. However, when crushed, it breaks easily. These challenges, coupled with the abundance of this material in the UK, have led chalk to be studied in recent years for a better understanding of its characteristics and behavior. One of the ways of improving the chalk behavior is with the addition of Portland cement to the material, which is developed in this research. The chalk used in the testing was collected in St. Nicholas, Kent, UK, and characterised as CIRIA Grade A/B, low to medium density. The material was crushed in the laboratory until it became sandy silt, with D50 of 0.035 mm. The material was mixed with high initial strength Portland cement, at 3, 5 and 7% in relation to the dry soil mass The results of unconfined compression, traction by diametral compression and initial stiffness (G0) tests showed a gain of strength with the increase of cement content and specific dry unit weights in the studied samples. The strength data was analyzed as a function of the porosity by the volumetric content of cement (/Civ), showing the influence of the level of cementation and compaction in the strength of the mixture. The adjustment exponent of 0.28 in the cementing agent volume generated better determination coefficients in the results. There was an almost linear relationship between initial stiffness and unconfined compression strength. The stiffness versus time curves showed a logarithmic trend for the evolution of G0 with time in all samples. In the durability tests, the higher the dry unit weight and cement content of the sample, the lower the mass loss. The stiffness remained practically constant during the 12 cycles.
Bansod, Yogesh Deepak. "Computational Simulation of Mechanical Tests of Isolated Animal Cells". Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-263397.
Texto completoLin, Bao-Yan y 林保延. "Estimation of the Dynamic Properties of Sands by Bender Element Tests". Thesis, 2005. http://ndltd.ncl.edu.tw/handle/64988652901855787926.
Texto completo國立臺灣科技大學
營建工程系
93
This research performed bender element tests with different frequencies of waves on Yaun-Lin sand and Hsin-Dian sand to study the effects of frequencies on the arriving time of shear wave; and the suitable range of frequencies was determined first. Then, bender element tests with suitable frequencies were carried out together with cyclic triaxial tests on Yaun-Lin sand to establish the relationship between shear wave velocity and liquefaction resistance. Test results showed that the arriving time of shear wave would be obviously underestimated and the signal received is very weak and hard to distinguish when the input frequency is below 5 kHz. When the input frequency is above 20 kHz, there would be larger errors in determination of the arriving time by different methods of analyses. There exists a quite good relationship between shear wave velocity and liquefaction resistance. Compared with the curves suggested by Andrus and Stokoe (1996), the liquefaction resistances estimated by bender element tests of this research are slightly higher than their results at the same shear wave velocities.
Rio, J. "Advances in laboratory geophysics using bender elements". Doctoral thesis, 2006. https://repositorio-aberto.up.pt/handle/10216/16198.
Texto completoRio, J. "Advances in laboratory geophysics using bender elements". Tese, 2006. https://repositorio-aberto.up.pt/handle/10216/16198.
Texto completoKrupička, Martin. "Stanovení anizotropie tuhosti brněnského téglu pomocí bender elementů". Master's thesis, 2020. http://www.nusl.cz/ntk/nusl-434787.
Texto completoSantos, Paulino André Dias. "Caracterização da rigidez inicial de areias utilizando Bender Elements". Master's thesis, 2015. http://hdl.handle.net/10316/38646.
Texto completoA caracterização adequada da rigidez de um solo é um aspeto fundamental na modelação do comportamento de qualquer obra geotécnica. Estudos efetuados comprovam que a rigidez é neste tipo de materiais altamente não linear e que só para extensões inferiores a aproximadamente 0.001% se pode assumir um comportamento elástico. Para tão baixas deformações é usual considerar que o solo apresenta uma rigidez constante denominada usualmente por módulo de distorção máximo, Gmax. No entanto para extensões superiores a rigidez tende a decair rapidamente, observando-se uma redução de cerca de 90% do seu valor para extensões da ordem de 1%. Uma das dificuldades na caracterização da curva de degradação da rigidez prende-se com a determinação de Gmax, visto que este parâmetro apenas pode ser obtido realizando ensaios que induzam na amostra níveis de deformação muito pequenos. Uma das possibilidades mais frequentemente utilizadas consiste na realização de ensaios laboratoriais usando bender elements. Este tipo de ensaios permite estimar a velocidade de propagação das ondas de corte, VS, num solo, a qual se encontra diretamente relacionada com o Gmax, desde que se assuma que, para estes níveis de deformação, o solo se pode considerar como estando em regime elástico. O trabalho realizado nesta dissertação tem como principal objetivo a determinação do valor de Gmax de dois tipos de solos arenosos da região de Coimbra, recorrendo a ensaios laboratoriais de bender elements. A avaliação do Gmax tem igualmente como propósito complementar a caracterização destes solos arenosos, que tem já vindo a ser realizada no Laboratório de Geotecnia da Universidade de Coimbra. Para uma maior facilidade de interpretação dos resultados foram utilizadas amostras reconstituídas através um método de pluviação desenvolvido localmente. O trabalho contempla a realização de ensaios em amostras com diferentes densidades relativas a fim de avaliar a influência deste parâmetro na rigidez inicial dos solos. Um outro aspeto analisado é o efeito do confinamento lateral e o seu impacto no valor de Gmax. Para tal, ao longo de cada ensaio a tensão de confinamento das amostras foi progressivamente aumentada até patamares pré-estabelecidos. Pretendeu-se ainda analisar a influência de carregamentos cíclicos no valor da rigidez, pelo que foram executados vários ciclos de carga e descarga em cada ensaio. Por último efetuou-se uma comparação detalhada dos resultados obtidos entre as duas areias de Coimbra ensaiadas bem como com outros valores de referência publicados na bibliografia para solos com características similares.
An adequate characterization of the soil stiffness is a fundamental aspect when modelling the behaviour of any geotechnical work. Studies show that the stiffness in this type of materials is highly nonlinear and that only for small strains, lower than about 0.001%, it is possible to assume an elastic behaviour. For such small strains it is assumed that the soil has a constant stiffness usually known as maximum shear modulus, Gmax. However, for higher strains, stiffness tends to decrease sharply, and a decrease of about 90% of its value can be reached for strains around 1%. One of the major difficulties when characterizing the stiffness degradation curve is related with the determination of Gmax, as it can only be obtained by performing tests that induce very small strain levels in the sample. One of most frequently used possibilities in laboratory testing is using bender elements. This type of tests allows the determination of the propagation velocity of the shear waves VS, in the soil, which is directly related to Gmax, if it is assumed that the soil remains within the elastic threshold. The work performed in this thesis primarily aims to evaluate the value of Gmax for two types of sandy soils of the Coimbra region, by performing bender elements tests. The determination of Gmax, is part of the characterization program established for these sandy soils that is currently being carried out at the Geotechnical Laboratory of the University of Coimbra. For a simpler interpretation of the results, reconstituted samples through a pluviation method developed locally were tested. The work also includes a set of tests with different densities in order to evaluate the influence of this parameter in the initial stiffness of the soil. Another aspect that will also be analysed further is the effect of lateral confinement on the value of Gmax. In order to achieve that, the confinement pressure in each test was progressively increased to predefined levels. The influence of cyclic loading on stiffness value was also analysed. Thus, different cycles of loading and unloading in each test were carried out in each test. Finally, a comparison of the results obtained for the two Coimbra sands is presented. Those results are also compared with reference values published in the literature for soils with similar characteristics.
Mohammad, Roshnara. "Dynamic properties of compacted soils using resonant column with self-contained bender elements". 2008. http://hdl.handle.net/10106/1001.
Texto completoJarvis, Kevin Donald Gibson. "The application of piezoceramic bender elements to the laboratory measurement of elastic wave velocities". Thesis, 1994. http://hdl.handle.net/2429/3452.
Texto completoSilva, Ana Rita Dias de Sousa e. "Numerical modelling of the dynamic behaviour of a soil in true triaxial tests with bender elements". Master's thesis, 2014. https://repositorio-aberto.up.pt/handle/10216/73440.
Texto completoSilva, Ana Rita Dias de Sousa e. "Numerical modelling of the dynamic behaviour of a soil in true triaxial tests with bender elements". Dissertação, 2014. https://repositorio-aberto.up.pt/handle/10216/73440.
Texto completoWang, Chung-Ju y 王崇儒. "Using bender elements to evaluate the shear wave velocity in dynamic centrifuge modeling test and its applocation". Thesis, 2010. http://ndltd.ncl.edu.tw/handle/10630303167185199692.
Texto completo國立中央大學
土木工程研究所
98
In this research, a bender elements system and the related software have been developed for evaluating the in-flight shear wave velocity in dynamic centrifuge tests. The in-flight shear wave velocity and the calculated maximum shear modulus profiles of the models were obtained. Before and after seismic events shear wave velocity profile can also be determined, and the profile is used to evaluate the change of dynamic soil property and the liquefaction potential of soil bed based soil resistance criteria in terms of shear wave velocity. During earthquakes the shear modulus would change with time. The developed bender element system is capable of measuring the evolution of shear wave velocity on the model during shaking as well. The test result shows that the shear wave velocities decrease with the increase of excess pore water pressure during shaking, while the shear wave velocities gradually increase as the excess pore water pressure dissipates after stop of shaking.
Silva, Joana Marques Saraiva de Almeida e. "Estudo de liquefacção estática e cíclica de um silte com recurso a ensaios triaxiais com Bender Elements". Master's thesis, 2010. http://hdl.handle.net/10216/60230.
Texto completoSilva, Joana Marques Saraiva de Almeida e. "Estudo de liquefacção estática e cíclica de um silte com recurso a ensaios triaxiais com Bender Elements". Dissertação, 2010. http://hdl.handle.net/10216/60230.
Texto completoChen, Fu-fang y 陳賦舫. "Use of bender elements to investigate the evolution of shear wave velocity during undrained shearing in triaxial tests". Thesis, 2011. http://ndltd.ncl.edu.tw/handle/05858860839108514076.
Texto completo國立中央大學
土木工程研究所
99
The cyclic shear stress induced by earthquakes would increase the excess pore water pressure and decrease the soil strength in a saturated sand deposit. For investigating the mechanism of sand during shearing, a pair of bender elements was mounted in both the cap and pedestal of the triaxial apparatus. Using the bender elements can measure the shear wave velocity while the saturated sand specimen was subjected to slow shearing. Therefore, the maximum shear modulus,Gmax, one of the key parameters for predicting dynamic behavior of soil, can be evaluated by the measured shear wave velocity (Vs) during the consolidated-undrained triaxial test at different stress paths. Before the test, the bender elements were waterproofed, shielded, and grounded in order to work in the saturated sand specimens and to reduce electromagnetic interference of received signals. Besides, for knowing the properties of bender elements and determining the criterion of arrival time of the measured wave, three kinds of exciting waveforms and different ranges of exciting frequencies were examined at the consolidation stage in advance. The test results showed that the most suitable transmitting signal was a single sine pulse with frequencies between 12 kHz to 15 kHz. The increase in the isotropic confining pressure increased the shear wave velocity. Nevertheless, during shearing, the shear wave velocity was affected by not only the effective confining pressure but also the stress state on the soil specimen. By the regression analysis, an empirical equation was proposed to predict the shear wave velocity based on the void ratio and the effective mean stress of soil specimen. The predicted values were closed to the measured ones when the stress ratio was greater than 0.5 and less than 3.
Chang, Hsin-Pei Nicol. "The relationship between void ratio and shear wave velocity of gold tailings". Diss., 2004. http://hdl.handle.net/2263/25319.
Texto completoDissertation (MEng)--University of Pretoria, 2006.
Civil Engineering
MEng
Unrestricted