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1
Villeneuve, Joey. "Laboratory Testing for Adfreeze Bond of Sand on Model Steel Piles". Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/37323.
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This study explored the available adfreeze data published in literature and the techniques used to obtain it. Two methods were selected and modified to complete series of adfreeze bond test. A model pile pull-out method consisting of pulling a pile out a large specimen of soil was the first method used. The second method was modified from an interface shearing apparatus developed by Dr. Fakharian and Dr. Evgin at the University of Ottawa in 1996 and allowed preparing, freezing and testing the specimen in place.
The material and soil tested for this study were provided by EXP Services Inc. The model pile, a galvanized HSS 114.3 x 8.6 section, is commonly used to install solar panels. Soil was taken from a future solar farm site in proximity to Cornwall, Ontario.
The study had for objective to develop a low cost adfreeze laboratory testing method. Limitations of the technics and apparatus used were observed. While the results of a model pile pull-out test compared to previous data publish by Parameswaran (1978), the interface shear series of test presented more limitations. The interface shearing method has been previously study by Ladanyi and Thériault (1990).
Issues with the interface shear method due to the water content of the soil as well as the range of normal stress applied to the specimen both during testing and freezing. The data obtained was inconclusive and the method will be studied in future research program.
This studied approach the adfreeze testing with new improvement. The main contribution of this study is the data obtained by measuring and observing adfreeze of ice poor sand with varying water content. The measurements allowed to study the effect that increasing water content has on the interface bond strength.
The modifications made to interface shear apparatus are also major new contribution provided by this research. The apparatus was converted in a small freezer chamber using insulation panel and vortex tubes. Which was used to freeze the specimen in the testing chamber and testing adfreeze in place without handling the shear box arrangement.
2
Jeffrey, John. "Investigating the performance of continuous helical displacement piles". Thesis, University of Dundee, 2012. https://discovery.dundee.ac.uk/en/studentTheses/9877bf01-2251-4b34-aa8b-0ff9fc36a264.
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The Continuous Helical Displacement (CHD) pile is an auger displacement pile developed by Roger Bullivant Ltd in the UK. The CHD pile is installed in-situ through the use of a drilling auger, in a similar fashion to European screw piles and as such, it has performance characteristics of both displacement and non-displacement piles Based on field experience, it is known that the load capacity performance of the CHD pile significantly exceeds the current design predictions, particularly when installed in sand. Model CHD piles were created in pluviated test beds at a range of different densities and compared to model displacement and non-displacement piles. The load tests show that the CHD piles have a similar ultimate capacity to displacement piles. Instrumentation of the model piles allowed load distribution throughout the pile length to be determined. The tests allowed design parameters to be established, with it being shown that the CHD has lower bearing capacity factors and higher earth pressure coefficients than current suggestions .The disturbance to the in-situ soil conditions caused by the installation of the CHD piles was measured using a model CPT probe. The CHD pile was found to cause significant changes in soil relative density laterally around the pile shaft while displacement piles show changes predominantly below the pile base. The CHD pile is found to cause a densification of the in situ soil for all relative densities with the greatest increase occurring in loose sand. The ultimate capacity of the CHD pile is determined from load tests carried out on field CHD piles with the aid of capacity prediction methods for piles which have not been loaded to their ultimate capacity. The results from model testing have been applied to field pile tests to allow the development of design parameters including appropriate pile diameter, bearing capacity factor Nq and the earth pressure coefficient k which are suitable for CHD piles.
3
Shublaq, E. W. "A study of model pile group-sand interaction". Thesis, University of Leeds, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375520.
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Abdelaziz, Gamal. "An axisymmetrical model for a single vertical pile in sand". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/NQ59226.pdf.
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Camões, Lourenço João. "Numerical Modelling of Non-Displacement Piles in Sand : The importance of the dilatancy in the resistance mobilization". Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASC033.
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Cette thèse se concentre sur la réponse des pieux installés dans le sable lorsqu'ils sont soumis à des actions verticales et en particulier concernant la pertinence du comportement volumétrique du sol sur cette réponse. À l'interface sol-pile, lorsque le sol est déformé par cisaillement, des déformations volumétriques (généralement dilatation) se produisent, ce qui provoque une importante variation de l'état de contrainte. Cela se fait à l'aide de modèles numériques par éléments finis en adoptant le modèle élastoplastique ECP, une loi constitutive réaliste pour décrire le comportement du sol dans le massif et celui se trouvant dans la zone où les déformations se localizent à l'interface sol-pieu. Ce modèle, formulé en contraintes effectives, est un modèle multiméchanismes qui tient compte des facteurs importants qui influencent le comportement du sol, comme l'élasticité non linéaire, la plasticité incrémentale ou la description de l'état critique. D'autres aspects importants, comme la distinction entre comportement dilatant et contractant, la définition de lois de flux ou distinction entre des différents états de compacité peuvent être considérés via les paramètres du modèle. Ce n'est qu'avec un modèle rhéologique avancé, capable de capturer le comportement réel du sol, qu'il sera possible de modéliser l'interaction sol-pieuThis thesis' focus is the response of non-displacement piles installed in sand when subjected to axial load, specifically in the relevance of soil's volumetric behavior on this response. At the soil-pile interface, when the soil is distorted by shear volumetric deformations (usually dilatation) occur, which causes a significant variation in the stress state. That is done with the support of finite element numerical models by adopting the elastoplastic ECP model, a realistic constitutive law for the soil and the soil-pile interface. This model, written in terms of effective stresses, is a multimechanisms model that takes into account important factors that influence soil behaviour, such as non-linear elasticity, incremental plasticity or the critical state definition. Other important aspects, such as the distinction between dilating or contractive behaviour, flow rule or density index, can be considered via the model parameters. Only with an advanced soil model, that captures the real behaviour of the soil, it is possible to model the involved phenomena
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Masson, Benoît. "Des piles de sable aux automates de sable". Phd thesis, Université de Nice Sophia-Antipolis, 2006. http://tel.archives-ouvertes.fr/tel-00144448.
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Dans cette thèse nous étudions différents systèmes dynamiques discrets permettant de simuler la formation des piles de sable. Le comportement des modèles de base SPM ou IPM(k) est bien connu dans des conditions initiales spécifiques. Nous étendons ces résultats à des conditions initiales plus générales, et nous introduisons le modèle SSPM qui ajoute de la symétrie à ces modèles et améliore leur réalisme. Dans un second temps, nous étudions un autre système dynamique, les automates de sable. Ils sont définis de manière analogue aux automates cellulaires, avec la contrainte supplémentaire qu'uneconfiguration n'admet pas de « trous ». Ces automates peuvent simuler tous les modèles de piles de sable définis localement, et à l'aide d'un cadre mathématique solide, ils permettent d'obtenir des résultats plus généraux. Nous nous intéressons à la dynamique des automates de sable, plus précisément aux propriétés de réversibilité d'un automate, et nous étudions la décidabilité de propriétés caractérisant les piles de sable classiques : conservation des grains et périodicité ultime.
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Cameron, Donald Anthony. "Analysis Of Buried Flexible Pipes In Granular Backfill Subjected To Construction Traffic". Thesis, The University of Sydney, 2005. http://hdl.handle.net/2123/680.
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This thesis explores the design of flexible pipes, buried in shallow trenches with dry sand backfill. The thesis reports the comprehensive analysis of twenty-two full-scale load tests conducted between 1989 and 1991 on pipe installations, mainly within a laboratory facility, at the University of South Australia. The pipes were highly flexible, spirally-wound, uPVC pipes, ranging in diameter from 300 to 450 mm. Guidelines were required by industry for safe cover heights for these pipes when subjected to construction traffic. The tests were designed by, and conducted under the supervision of, the author, prior to the author undertaking this thesis. As current design approaches for pipes could not anticipate the large loading settlements and hence, soil plasticity, experienced in these tests, finite element analyses were attempted. Extensive investigations of the materials in the installations were undertaken to permit finite element modelling of the buried pipe installations. In particular, a series of large strain triaxial tests were conducted on the sand backfill in the buried pipe installations, to provide an understanding of the sand behaviour in terms of critical state theory. Subsequently a constitutive model for the soil was developed. The soil model was validated before implementation in an element of finite element program, AFENA (Carter and Balaam, 1995). Single element modelling of the triaxial tests proved invaluable in obtaining material constants for the soil model. The new element was applied successfully to the analysis of a side-constrained, plate loading test on the sand. The simulation of the buried pipe tests was shown to require three-dimensional finite element analysis to approach the observed pipe-soil behaviour. Non-compliant side boundary conditions were ultimately adjudged chiefly responsible for the difficulty in matching the experimental data. The value of numerical analyses performed in tandem with physical testing was apparent, albeit in hindsight. The research has identified the prediction of vertical soil pressure above the pipe due to external loading as being the major difficulty for designers. Based on the finite element analyses of the field tests, a preliminary simple expression was developed for estimation of these pressures, which could be used with currently available design approaches to reasonably predict pipe deflections.
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Cameron, Donald Anthony. "Analysis Of Buried Flexible Pipes In Granular Backfill Subjected To Construction Traffic". University of Sydney. Civil Engineering, 2005. http://hdl.handle.net/2123/680.
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This thesis explores the design of flexible pipes, buried in shallow trenches with dry sand backfill. The thesis reports the comprehensive analysis of twenty-two full-scale load tests conducted between 1989 and 1991 on pipe installations, mainly within a laboratory facility, at the University of South Australia. The pipes were highly flexible, spirally-wound, uPVC pipes, ranging in diameter from 300 to 450 mm. Guidelines were required by industry for safe cover heights for these pipes when subjected to construction traffic. The tests were designed by, and conducted under the supervision of, the author, prior to the author undertaking this thesis. As current design approaches for pipes could not anticipate the large loading settlements and hence, soil plasticity, experienced in these tests, finite element analyses were attempted. Extensive investigations of the materials in the installations were undertaken to permit finite element modelling of the buried pipe installations. In particular, a series of large strain triaxial tests were conducted on the sand backfill in the buried pipe installations, to provide an understanding of the sand behaviour in terms of critical state theory. Subsequently a constitutive model for the soil was developed. The soil model was validated before implementation in an element of finite element program, AFENA (Carter and Balaam, 1995). Single element modelling of the triaxial tests proved invaluable in obtaining material constants for the soil model. The new element was applied successfully to the analysis of a side-constrained, plate loading test on the sand. The simulation of the buried pipe tests was shown to require three-dimensional finite element analysis to approach the observed pipe-soil behaviour. Non-compliant side boundary conditions were ultimately adjudged chiefly responsible for the difficulty in matching the experimental data. The value of numerical analyses performed in tandem with physical testing was apparent, albeit in hindsight. The research has identified the prediction of vertical soil pressure above the pipe due to external loading as being the major difficulty for designers. Based on the finite element analyses of the field tests, a preliminary simple expression was developed for estimation of these pressures, which could be used with currently available design approaches to reasonably predict pipe deflections.
9
Sheikhtaheri, Mohamadjavad. "Experimental and Numerical Modeling Studies for Interpreting and Estimating the p–δ Behavior of Single Model Piles in Unsaturated Sands". Thèse, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/30712.
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The design of pile foundations in conventional geotechnical engineering practice is based on the soil mechanics principles for saturated soils. These approaches are also extended to pile foundations that are placed totally or partially above the ground water table (i.e., vadose zone), where the soil is typically in a state of unsaturated condition. Such approaches lead to unrealistic estimations of the load carrying capacity and the settlement behavior of pile foundations. Some studies were undertaken in recent years to understand the influence of the matric suction towards the bearing capacity of model pile foundations placed in unsaturated fine-grained and coarse-grained soils. The conventional and methods were modified to interpret the contribution of shaft carrying capacity of single piles in fine-grained soils (e.g., Vanapalli and Taylan 2011, Vanapalli and Taylan 2012). Also, the conventional method has been used to understand the contribution of matric suction towards the shaft resistance in unsaturated sands (Vanapalli et al. 2010).
One of the key objectives of the present research study is directed to determine the contribution of matric suction towards the bearing capacity and settlement behavior of model single pile foundations in unsaturated sands. A series of single model pile load tests were performed in a laboratory environment to study the contribution of the matric suction towards the total, shaft, and base bearing capacity of the model piles with three different diameters (i.e., 38.30, 31.75, and 19.25 mm) in two unsaturated sands (i.e., a clean commercial sand and a super fine sand). Hanging column method (i.e., plexi glass water container) was used to control the matric suction values in the compacted sands in the test tank by varying the water table. The results of the testing programs indicate the significant contribution of the matric suction towards the bearing capacity of single model piles (i.e., 2 to 2.5 times of base bearing capacity and 5 times of shaft bearing capacity under unsaturated conditions in comparison with saturated condition). The test results were interpreted successfully by modifying the conventional methods for estimating the pile shaft bearing capacity (i.e., β method) and base bearing capacity (i.e., Terzaghi 1943, Hansen 1970 and Janbu 1976). In addition, semi-empirical methods were proposed for predicting the bearing capacity of single model piles using the effective shear strength parameters (i.e., c' and ϕ') and the soil-water characteristic curve (SWCC). There is a good agreement between the measured and the predicted bearing capacity of single model piles using the semi-empirical models proposed in this study.
In addition, numerical investigations were undertaken using the commercial finite element analysis program SIGMA/W (Geostudio 2007) to simulate the load-displacement (i.e., p-δ) behavior of the single model piles for the two sands (i.e., clean commercial sand and super fine sand) under saturated and unsaturated conditions. An elastic-perfectly plastic Mohr-Coulomb model that takes into account the influence of the matric suction was used to simulate the load-displacement (i.e., p-δ) behavior. The numerical approach proposed in this thesis is simple and only requires the information of the effective shear strength parameters (i.e., c' and ϕ'), the elastic modulus (i.e., Esat) under saturated conditions, the soil-water characteristic curve (SWCC), and the distribution of the matric suction with respect to depth.
The approaches proposed in this thesis can be extended to determine the in-situ load carrying capacity of single piles and also simulate the load-displacement (i.e., p-δ) behavior. The studies presented in this thesis are promising and encouraging to study their validity in-situ conditions. Such studies will be valuable to implement the mechanics of unsaturated soils into geotechnical engineering practice.
10
Mazutti, Júlia Hein. "Estudo do atrito lateral no arrancamento de estacas modelo instaladas por fluidização em areia". reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2018. http://hdl.handle.net/10183/183019.
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O objetivo desta dissertação consiste em aprofundar o entendimento dos mecanismos que controlam o atrito lateral sob arrancamento de estacas instaladas por fluidização em areia. A técnica de instalação é estudada como uma alternativa para a utilização de estacas torpedo na fixação de plataformas offshore. Trabalhou-se em laboratório com o arrancamento de estacas metálicas circulares em modelo reduzido. Foram utilizados três diâmetros de estacas modelo, simulando três diferentes escalas: 14 mm (1:76), 16,2 mm (1:67) e 21,3 mm (1:50). Foram realizados 8 ensaios de arrancamento (24 horas após a fluidização) em estacas modelo instaladas por fluidização em solo arenoso com densidade relativa de 50% e submetido à sobrecarga de 2,236 kPa. Foram também realizados 17 ensaios de arrancamento em estacas modelo pré-instaladas (sem fluidização) em areia com densidade relativa de 30%, simulando uma instalação sem perturbação do solo, uma vez que esta é a densidade relativa aproximada que a areia atinge após o processo de fluidização. Os resultados foram comparados com pesquisas anteriores de arrancamento de estacas instaladas por fluidização em areia. Para um aumento médio de 2 vezes a tensão vertical efetiva nas estacas modelo instaladas por fluidização com sobrecarga, observa-se um ganho médio de 1,8 na resistência. O coeficiente de empuxo lateral de serviço para estes ensaios não apresentou diferenças significativas em relação ao mesmo tipo de ensaio sem sobrecarga. As estacas instaladas por fluidização com sobrecarga e estacas pré-instaladas (sem perturbação) apresentam valores de constantes e independentes das profundidades instaladas, com respectivas médias de 0,15 e 0,31. O valor de parece aumentar com o tempo para as estacas fluidizadas (efeito setup) devido à reconstituição das tensões radiais. Os valores de estacas cravadas em areia densa diminuem seu valor com o aumento da profundidade instalada (e da tensão efetiva média atuante), por restrição de dilatação, tendendo ao valor de encontrado para ensaios pré-instalados realizados neste trabalho.The main goal of this study is to deepen the understanding of the shaft friction behavior under tension loads of piles installed by fluidization in Osório sand. The installation technique is studied as an alternative for the use of torpedo piles in offshore platforms anchoring. This work was done in laboratory with metallic circular piles in reduced model. Three diameters of model piles were used, simulating three different scales: 14 mm (1:76), 16,2 mm (1:67) and 21,3 mm (1:50). Eight pullout tests (24 hours after fluidization) were carried out on model piles installed by fluidization in sandy soil with a relative density of 50% and subjected to a surcharge of 2,236 kPa. Eighteen pullout tests were performed on pre-installed (non-fluidized) model piles in sand with a relative density of 30%, simulating an installation without soil disturbance, since this is the approximate relative density reached after the process of fluidization. The results were compared with previous studies of pullout resistance of fluidized piles in sand. For an average increase of 2 times the vertical effective stress in the model piles installed by fluidization with surcharge, an average increase of 1,8 times is observed in the pullout resistance. The lateral earth pressure coefficient on the pile shaft for these tests did not show significant differences in relation to the same type of test without surcharge. For tests installed by fluidization and pre-installed tests (without soil disturbance), remains constant and independent of the installed depths, with respective averages of 0,15 and 0,31. The value seems to increase with time for fluidized tests (setup effect) due to the reconstitution of the radial tensions. The values for pullout tests in driven model piles in dense sand decrease their value with the increase of the installed depth (and the increase of the vertical effective stress), by restriction of the expansive behavior, tending to the value found for pre-installed tests carried out in this work.
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Robinson, R. B. "Piles in sand and in sand overlying clay". Thesis, University of South Wales, 1989. https://pure.southwales.ac.uk/en/studentthesis/piles-in-sand-and-in-sand-overlying-clay(8c43e7a9-c869-4a1f-a044-30741f2964bc).html.
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This thesis examines the behaviour of single 60mm and 114mm segmented tubular steel piles driven and placed into loose sand and loose sand overlying clay. The soil was placed and instrumented under controlled conditions in a 3.0m diameter by 3.0m deep concrete tank. The 60mm pile was dynamically driven using a pneumatically controlled driving rig, whilst the 114mm pile was driven at a constant rate of penetration via a hydraulic jack. The static and dynamic axial load distributions were monitored for the 60mm pile. The variation in local shaft friction and radial effective stress were monitored along the pile shaft of the 114mm pile, together with the distribution of axial load within the pile. The pore water pressure was continuously monitored at selected points in the clay from the placement of the overburden to the final stages of the experiment. The density of the sand was carefully controlled during placement and was subsequently measured at the relevant point in the experiment. Vertical and radial displacements were monitored within the sand. For the two soil profiles radial shear and vertical effective stresses were recorded at a defined level within the strata. Data from both the pile and soil instrumentation was recorded throughout the pile installation and load testing programme by an Orion Data Logger which was interfaced with a Commodore PET micro computer. The results show: (i) During pile installation the major principal stress acting at depth within a soil profile, appears to emanate from the face of the active wedge driven ahead of the pile. (ii) The boundary of the sand/clay interface has a considerable effect on the development of soil displacements and the effective vertical stress developed within the overlying sand. (iii) The radial displacement during pile installation is directly related to the pile diameter. Within a sand profile the peak radial displacement can be predicted using an empirical compaction factor adjustment to a theoretical representation of radial soil movement. (iv) In sand, the local unit shaft friction and the radial effective stress are practically constant along the pile shaft for a given pile embedment and increases at a diminishing rate with pile embedment. (v) At full pile embedment and ultimate applied load, the local coefficient of earth pressure KZ, for a driven pile may approach or exceed the value of Kp near the top of the pile and tend to a lower limit of 0.6 near the pile base. (vi) For a placed insitu pile at ultimate applied load, the local coefficient of earth pressure Kz may be less than Kp near the top of the pile and tend to Ka near the pile base. (vii) Adjacent to the pile shaft the radial effective stress is the major stress. (viii) The development of shaft friction is directly related to displacements within the surrounding sand and on the sand/clay interface. (ix) The influence of the underlying clay layer affects the development of shaft friction to varying limits above and below the sand/clay interface. (x) For shallow pile penetrations into the clay layer the drawdown of sand and sand plug driven ahead of the pile significantly reduces the pore water pressure generated at the soil/pile interface. (xi) The development and radial distribution of pore water pressure within the clay can be represented be a logarithmic expression. (xii) The maximum compressive strain due to pile installation in a sand profile radiates from below and around the pile base. These results are compatible with and extend previous research work at the Polytechnic of Wales. They illustrate how soil behaviour and soil/pile interaction are influenced by the method of pile installation and the boundary effects of an incompatible underlying layer.
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TAKAGI, Kenji, 光夫 野津, Mitsuo NOZU, 利弘 野田, Toshihiro NODA, 敏浩 高稲, Toshihiro TAKAINE i 健次 高木. "水～土連成計算を用いた砂杭拡径による砂地盤の締固めメカニズムの一考察". 土木学会, 2001. http://hdl.handle.net/2237/8642.
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Sakr, Mohammed A. "Centrifuge modeling of tapered piles in sand". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0018/MQ58078.pdf.
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Al-Hadid, Tareq N. M. "Pull-out tests on bent piles in sand". Thesis, University of Sheffield, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358951.
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Axelsson, Gary. "Long-term set-up of driven piles in sand". Doctoral thesis, KTH, Civil and Environmental Engineering, 2000. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3009.
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Nazir, Ramli Bin. "The moment carrying capcity of short piles in sand". Thesis, University of Liverpool, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240279.
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Peng, Jing-Rui. "Behaviour of finned piles in sand under lateral loading". Thesis, University of Newcastle Upon Tyne, 2006. http://hdl.handle.net/10443/1732.
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Reviewing the development of offshore wind farms, large-diameter monopiles have been widely used as foundations for offshore wind structures. Unlike onshore foundations which are mainly used to transmit vertical load into the ground, offshore foundations are usually subjected to large environmental loads from wind, wave and current which could exceed 30% of their gravity load. In order to improve the lateral resistance of monopiles, a finned pile has been proposed. Empirical and Numerical methods were used to simulate pile head lateral load and displacement (P-Y) curves, and the efficiency of fins under static loading has been estimated. Pile soil response along the pile was predicted based on the distribution of deflection, bending moment, shear force and soil resistance. Three-dimensional charts from FEM analysis represent pile and soil responses especially the soil reaction around the fins. To compare the lateral resistances of a monopile and of finned piles with various fin dimensions, 1 G model tests were carried out. Tests were conducted in a 1 cubic metre steel tank filled with dry dense sand. Based on the results of ultimate lateral loads, fin efficiency under static and repeated loadings was determined. A modified relationship of load deflection behaviour has been suggested. Small-scale lateral cyclic load tests were performed in order to determine the effect of fin length on the lateral displacement of laterally loaded piles. Ten thousand cycles were used in each test to represent twenty years of environmental loading on offshore structures. Variables included the magnitude, frequency and direction ofthe load, the pile tip condition and the fin length. The efficiency of fins was evaluated by measuring the reduction of displacement of the pile head. The relationship between maximum load and displacement established from lateral load-displacement curves demonstrates that fins have significant impact on vertical and horizontal displacements. Piles subjected to combined loads were tested, and the failure envelopes of normalised combined loads represent the lateral resistance increase resulted from the use of finned piles. Under combined cyclic loading with various load features, a finned pile showed better performance in lateral resistance than a monopile. In order to achieve the optimum fin efficiency, the ideal fin width should be equal to half of the pile diameter and the fin length should be equal to half of the pile length. Outcomes from this research provide concepts for laterally loaded piles and useful parameters for the design of finned piles. The device of cyclic loading system and the use of 3D finite element method (FEM) can be applied in the future study of finned piles.
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Marshall, Alec. "Tunnelling in sand and its effect on pipelines and piles". Thesis, University of Cambridge, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.611442.
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Rafiei, A. "Understanding the thermo-mechanical behaviour of thermal piles in sand". Thesis, University College London (University of London), 2017. http://discovery.ucl.ac.uk/1544011/.
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Thermal piles are piled foundations that can be used both to extract heat at shallow depth from the ground and to transfer load from the structure to the ground. Despite an increased number of applications of thermal piles in recent years, knowledge of the thermo-mechanical behaviour of thermal piles is still limited. The literature reveals that additional thermal loading results in considerable induced axial load and stress along the pile, that can lead to a reduction in safety factor down to 1. Also, there are inconsistencies in the literature regarding the thermo-elastic/plastic, reversible/irreversible response of thermal piles and also on the effects of cyclic thermal loading on the side shear friction at the soil–pile interface. Moreover, the framework proposed in the Thermal Pile Standard (Ground Source Heat Pump Association, 2012) has not been tested for various soils conditions. In this study, the effect of thermo-mechanical loading on the mechanical performance of thermal piles and the soil–pile interface is investigated. A 1g laboratory model was developed using a stainless steel model pile embedded in medium-dense, dry sand. Strain and temperature along the pile were monitored using multiplexed fibre Bragg grating sensors. A 2D finite difference heat transfer model was developed in Matlab, predicting the temperature profiles within the soil. Findings from the numerical model were used to design the location of the temperature sensors in the soil. Laboratory tests were divided into five scenarios, involving both shaft resisting and shaft and base resisting piles. It was found that under thermo-mechanical loading, up to 68.4% of the maximum induced load was transferred to the pile toe for the shaft resisting pile, compared to virtually none under mechanical loading. It was further found that the level of restraint caused by medium-dense sand with a relative density of 57% was rather limited in the absence of surcharge load and the degree of freedom varied between 0.97 and 1.0. Moreover, it was found that the location of the null point shifts during each heating/cooling period. For a shaft and base resisting pile heated up to 50°C, the maximum induced thermal load was found to be 90% of the ultimate capacity of the pile. The maximum induced stress remained below the BS 8004:1986 (British Standards Institution, 1986) recommendations. Irreversible settlements were observed for both types of pile. The load threshold, where the limit to thermo-elastic behaviour was observed, was found to be up to 18% of the ultimate pile capacity, while this value was up to 31% in the case of shaft and base resisting pile. Despite an increase in the side friction during heating periods (up to 32% compared to the friction under ultimate state mechanical loading), the subsequent cooling periods seemed to reduce the friction level, and cyclic skin friction degradation and accumulation of pile settlement were observed in the heating and cooling cycles. The results also show deviations from the proposed framework for a model pile in sand mainly due to a variable friction angle at the soil–pile interface.
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Cowburn, S. J. "An experimental investigation of cyclically, axially loaded piles in sand". Master's thesis, University of Cape Town, 1993. http://hdl.handle.net/11427/8303.
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Bibliography: leaves 91-93.The research work involved the installation and cyclic load testing of large-scale pressure-grouted, instrumented piles in sand in the laboratory. The major objective of this experimental investigation was to establish the effects of the mean cyclic load level and amplitude on the pile behaviour during cyclic loading. Of particular interest was the study of the skin friction distributions along the pile shafts in order to understand the processes involved. Cyclic loading was limited to one-way loading in load-controlled mode. A literature review showed a lack of experimental data on the cyclic behaviour of large-scale pressure-grouted piles. The results of a number of small model tests in sand are discussed and the major trends of pile performances are highlighted to facilitate comparison of the observations made in this research. It was found that no definite testing procedure for cyclically-loaded piles is common to the various investigations. A research program and procedure of load applications was therefore developed to allow the isolation of the individual influences of the most significant cyclic parameters, the mean cyclic load level and the amplitude. In total 12 piles were installed using the same sand preparation and pile installation techniques. The tests only varied with regard to the applied loading procedure
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Alansari, Omar Mohamed A. "Capacity and behavior of steel pipe piles in dry sand /". Digital version accessible at:, 1999. http://wwwlib.umi.com/cr/utexas/main.
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Xu, Xiangtao. "Investigation of the end bearing performance of displacement piles in sand". University of Western Australia. School of Civil and Resource Engineering, 2007. http://theses.library.uwa.edu.au/adt-WU2007.0086.
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[Truncated abstract] The axial performance of piles in sand remains an area of great uncertainty in geotechnical engineering. Over the years, database studies have shown that the existing method for offshore piles (e.g. API 2000) is unreliable. There is therefore a clear need for an improved predictive method, which incorporates the state-ofthe- art understanding of the underlying controlling mechanisms. This Thesis is dedicated to address the factors influencing the end bearing performance of displacement piles in siliceous sand with a view to proposing and justifying an improved design formulation. Firstly, a database of displacement pile load tests in sand with CPT data was compiled in collaboration with James Schneider (Schneider 2007). It features the widest database with also the latest available pile load test data (e.g. Euripides, Ras Tanajib, Drammen etc) in electronic form. Evaluation of the three new CPTbased methods (Fugro-05, ICP-05 & NGI-05) against this database has revealed a broadly similar predictive performance despite their end bearing formulations being remarkably different. This anomaly promoted the author to extend the database to include additional tests with base capacity measurements to form new base capacity databases for driven and jacked piles, which resulted in the UWA- 05 method for end bearing of displacement piles in sand. This method accounts for the pile effective area ratio, differentiates between driven and jacked piles, and employs a rational qc averaging technique. ... Field tests were performed in Shenton Park, Perth to supplement the database study and, in particular, to examine the effect of the incremental filling ratio (IFR). 10 open-ended and 2 closed-ended piles were tested in compression followed by tension. The test results provide strong support for the UWA-05 method for base capacity evaluation employing the CPT qc values and the effective area ratio. A series of jacked pile tests was carried out on the UWA beam centrifuge, to further explore the factors affecting pile base response. In total, four uniform and four layered centrifuge samples were prepared and tested at various stress levels and relative densities using three separate pile diameters. The resistance ratio (qb0.1/qc,avg) is found to be independent of the absolute pile diameter, effective stress and soil relative density. The tests in layered soil enabled quantification of the reduction in penetration resistance when a pile/cone approaches a weak layer and revealed the significant influence on base stiffness of underlying soft clay layers. The stiffness decay curves (G/GIN vs. w/D, where GIN is initial operational shear stiffness) measured in static load tests were found to vary with ratios of GIN/qc, while there was a unique relationship between G/GIN and qb/qc. A detailed parametric study was carried out (using the FE code PLAXIS) by idealising pile penetration using a spherical cavity expansion analogue in layered soil. The numerical predictions compare well with the centrifuge results and their generalization enabled guidelines to be established for end bearing in layered soil.
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Mirzoyan, Artak Davit. "Lateral Resistance of Piles at the Crest of Slopes in Sand". Diss., CLICK HERE for online access, 2007. http://contentdm.lib.byu.edu/ETD/image/etd2088.pdf.
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Xiao, Qiong. "The loading path dependence of sand constitutive behaviour and its relationship with pressure dip in sand piles". Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/47037/.
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The subject of granular materials attracts substantial interests from both the academic and engineering communities. Their ubiquitous existences in nature and industries certify their engineering importance. Although relatively straightforward at the particle scale, the collective response of granular materials could be very complicated. The pressure dip under a sand pile is one among many intriguing phenomena that granular materials exhibit. It refers to a small dip in pressure appearing underneath the sand pile with the peak pressure observed away from the centre of the sand pile. Since first reported by Hummel and Finnan (1920), this counter-intuitive phenomenon has attracted extensive research endeavours in the past few decades. It is now generally believed that the construction history is crucial to the pressure dip formation, but a quantitative explanation is not yet available. An in-depth explanation in pressure dip formation would range three different scales: the particle-scale, the continuum-scale when the material could be treated as a representative volume element (RVE) and the system scale, in this case, the scale of the sand pile. Discrete element method (DEM) is a great tool in the study of granular materials by modelling it directly from the particle scale. This research sets out to investigate the pressure dip formation of granular materials using the discrete element method. It is however noted that the dimension of the system that DEM can practically simulate is limited. Therefore, the research project is achieved by conducting DEM simulation of sand pile and DEM simulation of elementary behaviour in parallel. Numerical experiments have been carried out using discrete element method to simulate the formation of sand pile in the three-dimension (particle diameter of 1.2 ± 0.4 mm) with the base plane diameter of 260mm , following three different procedures: a) boundary removal method; b) rain deposition and c) point deposition. Pressure dip phenomenon is observed following the point deposition but not the boundary removal method and rain deposition method. The stress distribution of invariants p,q,b are studied within the sand pile at the final stage. The boundary removal method and rain deposition method result in a larger confining pressure and deviatoric stress in the centre than the point deposition method, with b value approximately 0.2 for the three methods. This differences in pressure profiles suggest that the history dependence and the loading path dependence of granular materials play a central role in explaining the pressure dip formation. Discrete element simulations have also been conducted to investigate the RVE stress-strain responses of the granular materials. The numerical algorithm previously proposed by Li et al. (2013; 2016) has been implemented in LIGGGHTS. Numerical experiments have been conducted to study the effect of void ratio and the intermediate principal stress ratio b on the material response to proportional loading, as well as to non-proportional loading using the radius expansion method. It shows the peak and critical stress ratio are both decreased with the increase of b value. With regards to the non-proportional loading path, significant plastic deformation is observed especially with a larger stress ratio. The packing following all the three construction methods are in a loose state. And their initial structures are different from that following the radius expansion method. A sample is extracted from the deposited specimen under the boundary removal method to study the impact of the initial state. A smaller shear stress with a larger void ratio is observed for the deposited sample than the radius expansion prepared sample for the triaxial shear. Furthermore, under the rotation shear, the size of strain trajectory is increased larger for the deposited sample when increases the stress ratio. The “stress-force-fabric” (SFF) relationship is employed to interpret the effect of internal structure on material constitutive behaviour. Due to the higher value of average particle size and larger probability of strong contact force for the deposited sample, it produces a larger average coordination number and directional averaged contact force, accompanied with a smaller degree of fabric anisotropy and contact force anisotropy. This may be the reason of the lower shear resistance during shearing. Post-processing of the particle-level stress data from the sand pile simulations suggests that granular materials form different internal structure and experience different stress history following different construction methods. For the point deposition, a larger magnitude of σrz and a higher degree of fabric anisotropy are observed in the central region at the progressive stages. It implies that the constitutive phenomenon has a relationship with the path of the construction history. In addition, the point deposition test also generates a larger rotation of the major principal stress direction than the boundary removal and rain deposition tests. According to RVE simulations, it suggests the granular materials are under a triaxial compression loading path and a rotational loading path underneath the apex for the rain deposition and point deposition respectively. This increases the probability of forming arches and granular materials may experience a higher plastic deformation underneath the central apex during the point deposition. The particle-scale mechanism has been carried out to study the material behaviour with the loading path dependence of sand pile. Different stress field is observed with various construction histories. It demonstrates the pressure dip phenomenon may relate to the memory of the fabric anisotropy and the potential effect of plastic deformation. Moreover, a better understanding in this problem is believed to improve the problems of silos, retaining wall and embankments. It may be useful for the development of constitutive modelling of the stress field.
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Leo, Riccardo. "The axial response of offshore piles in sand from large scale tests". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017.
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This thesis focuses on deep foundations used in offshore environment, in particular for offshore wind turbines. Piles are necessary when the bearing capacity of the shallow soil layers is not enough to ensure stability. Piles can work on both axial and lateral response. In the thesis only axially loaded piles will be considered. The analysis of the axial behavior of piles should be considered in terms of ultimate capacity as well as the load transfer mechanism between the pile and the soil.
The technical aim of this thesis concerns the understanding of the load transfer curves, their extrapolation and the exploration of load distribution along the pile during a given load. To achieve this, a thorough study of literature on current design methods is carried out and two instrumented piles will be analysed in order to understand how the load is distributed along the pile shaft and how experimental load transfer curves can be extrapolated.
The more general aim of this work is to optimize design procedures and try to reduce the cost related piles and their installation in offshore environment, since it is quite known to be higher than onshore fields, as it will be explained in the first chapter of this thesis.
A geotechnical software IGtH Pile developed by the Institute of geotechnical Engineering (IGtH), Leibniz Universität Hannover will be used in the evaluation of the ultimate capacity and the results will be compared with a Matlab code developed at the IWES research institute.
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Deeks, Andrew David. "An investigation into the strength and stiffness of jacked piles in sand". Thesis, University of Cambridge, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.612501.
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Nunez, Ian Louis. "Centrifuge model tension piles in clay". Thesis, University of Cambridge, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.316783.
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Weaver, Thomas Jay. "Behavior of liquefying sand and CISS piles during full-scale lateral load tests /". Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC IP addresses, 2001. http://wwwlib.umi.com/cr/ucsd/fullcit?p3029643.
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Kevan, Luke Ian. "Full-Scale Testing of Blast-Induced Liquefaction Downdrag on Driven Piles in Sand". BYU ScholarsArchive, 2017. https://scholarsarchive.byu.edu/etd/6966.
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Deep foundations such as driven piles are often used to bypass liquefiable layers of soil and bear on more competent strata. When liquefaction occurs, the skin friction around the deep foundation goes to zero in the liquefiable layer. As the pore pressures dissipate, the soil settles. As the soil settles, negative skin friction develops owing to the downward movement of the soil surrounding the pile. To investigate the magnitude of the skin friction along the shaft three driven piles, an H-pile, a closed end pipe pile, and a concrete square pile, were instrumented and used to measure soil induced load at a site near Turrell, Arkansas following blast-induced liquefaction. Measurements were made of the load in the pile, the settlement of the ground and the settlement of piles in each case. Estimates of side friction and end-bearing resistance were obtained from Pile Driving Analyzer (PDA) measurements during driving and embedded O-cell type testing. The H-pile was driven to a depth of 94 feet, the pipe pile 74 feet, and the concrete square pile 72 feet below the ground surface to investigate the influence of pile depth in response to liquefaction. All three piles penetrated the liquefied layer and tipped out in denser sand. The soil surrounding the piles settled 2.5 inches for the H-pile, 2.8 inches for the pipe pile and 3.3 inches for the concrete square pile. The piles themselves settled 0.28 inches for the H-pile, 0.32 inches for the pipe pile, and 0.28 inches for the concrete square pile. During reconsolidation, the skin friction of the liquefied layer was 43% for the H-pile, 41% for the pipe pile, and 49% for the concrete square pile. Due to the magnitude of load felt in the piles from these tests the assumption of 50% skin friction developing in the liquefied zone is reasonable. Reduced side friction in the liquefied zone led to full mobilization of skin friction in the non-liquefied soil, and partial mobilization of end bearing capacity. The neutral plane, defined as the depth where the settlement of the soil equals the settlement of the pile, was outside of the liquefied zone in each scenario. The neutral plane method that uses mobilized end bearing measured during blasting to calculate settlement of the pile post liquefaction proved to be accurate for these three piles.
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Abbassian, Fariba. "Behaviour of simple and compound piles in saturated sand under horizontal and oblique pull". Thesis, Queen Mary, University of London, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285070.
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Reddy, Eadala Sai Baba. "An investigation into the behaviour of piles in sand under vertical cyclic tensile loads". Thesis, University of Nottingham, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.339687.
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Juirnarongrit, Teerawut. "Effect of diameter on the behavior of laterally loaded piles in weakly cemented sand /". Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC IP addresses, 2002. http://wwwlib.umi.com/cr/ucsd/fullcit?p3071009.
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Hollenbaugh, Joseph Erick. "Full-Scale Testing of Blast-Induced Liquefaction Downdrag on Auger-Cast Piles in Sand". BYU ScholarsArchive, 2014. https://scholarsarchive.byu.edu/etd/5494.
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Deep foundations like auger-cast piles and drilled shafts frequently extend through liquefiable sand layers and bear on non-liquefiable layers at depth. When liquefaction occurs, the skin friction on the shaft decreases to zero, and then increases again as the pore water pressure dissipates and the layer begins to settle, or compact. As the effective stress increases and the liquefiable layer settles, along with the overlaying layers, negative skin from the soil acts on the shaft. To investigate the loss of skin friction and the development of negative skin friction, soil-induced load was measured in three instrumented, full-scale auger-cast piles after blast-induced liquefaction at a site near Christchurch, New Zealand. The test piles were installed to depths of 8.5 m, 12 m, and 14 m to investigate the influence of pile depth on response to liquefaction. The 8.5 m pile terminated within the liquefied layer while the 12 m and 14 m piles penetrated the liquefied sand and were supported on denser sands. Following the first blast, where no load was applied to the piles, liquefaction developed throughout a 9-m thick layer. As the liquefied sand reconsolidated, the sand settled about 30 mm (0.3% volumetric strain) while pile settlements were limited to a range of 14 to 21 mm (0.54 to 0.84 in). Because the ground settled relative to the piles, negative skin friction developed with a magnitude equal to about 50% of the positive skin friction measured in a static pile load test. Following the second blast, where significant load was applied to the piles, liquefaction developed throughout a 6-m thick layer. During reconsolidation, the liquefied sand settled a maximum of 80 mm (1.1% volumetric strain) while pile settlements ranged from 71 to 104 mm (2.8 to 4.1 in). The reduced side friction in the liquefied sand led to full mobilization of side friction and end-bearing resistance for all test piles below the liquefied layer and significant pile settlement. Because the piles generally settled relative to the surrounding ground, positive skin friction developed as the liquefied sand reconsolidated. Once again, skin friction during reconsolidation of the liquefied sand was equal to about 50% of the positive skin friction obtained from a static load test before liquefaction.
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Abood, Awad Shihan. "Load capacity of piled foundations under non-cyclic and cyclic uplift loading". Thesis, Cardiff University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329618.
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Wu, Zexiang. "Modélisation du comportement des sables sous la condition de cisaillement simple et applications au calcul des pieux". Thesis, Ecole centrale de Nantes, 2017. http://www.theses.fr/2017ECDN0045/document.
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La thèse vise à étudier le comportement mécanique des sables sous la condition de cisaillement simple et à son application au calcul des pieux. Tout d'abord, un modèle de sable récemment développé (SIMSAND) prenant en compte l'état critique est introduit avec une procédure directe de détermination des paramètres. Le modèle est implanté dans un code de calcul aux éléments finis qui a fait l’objet de différentes validations. Ensuite, le modèle est amélioré en considérant l'anisotropie inhérente lors de la rotation des contraintes principales sous la condition de cisaillement simple et a été validé en utilisant les résultats des essais tri axiaux et de cisaillement simple sur le sable de Fontainebleau. Les essais de cisaillement simple sont analysés en imposant les conditions de sollicitations réelles tridimensionnelles appliquées par l’appareillage utilisé. L'inhomogénéité de l'échantillon avec l'effet de la taille de l'échantillon est également étudiée. Puis, des essais de cisaillement simple cycliques drainés et non-drainés sur le sable de Fontainebleau sont effectués pour étudier les caractéristiques sous charges cycliques, telles que la dégradation de la contrainte normale effective et l'accumulation de la déformation volumique, compte tenus de certains facteurs comme l’indice des vide initial, la contrainte normale appliquée, le rapport de contrainte de cisaillement cyclique et le rapport de contrainte de cisaillement moyenne. Sur la base de ces résultats, deux modèles analytiques sont proposés pour prédire la dégradation à long terme de la contrainte normale effective et l'accumulation des déformations volumiques en fonction du nombre de cycles. En outre, les essais cycliques de cisaillement simple sont simulés par le modèle SIMSAND amélioré en utilisant une technique d'inversion de contrainte. Enfin, on simule une série de pieux modèles sous charges monotone et cyclique pour laquelle la résistance en pointe du pieu est évaluée ainsi que la réponse du sol entourant le pieuThe thesis aims to study the mechanical behaviour of sand under simple shear condition and to apply the results to the numerical simulation of pile foundation. First, a recently developed critical state sand model (SIMSAND) is introduced with a straight forward procedure of parameters determination, implemented into a finite element code and then subjected to a series of validations. Then, the model is enhanced by considering the inherent anisotropy during the principal stress rotation under the simple shear condition and validated by using results of both triaxial tests and simple shear tests on Fontainebleau sand. Simple shear tests are analysed by simulating in three-dimensions the real conditions imposed by the simple shear apparatus. The inhomogeneity of the samples with the effect of sample size is also investigated. Furthermore, undrained and drained cyclic simple shear tests on Fontainebleau sand are conducted to investigate the cyclic responses, such as the effective normal stress degradation and the volumetric strain accumulation, respectively, considering some impact factors such as the initial void ratio, the normal stress, the cyclic shear stress ratio and the average shear stress ratio. Based on these results, two analytical models are proposed to predict the long-term degradation of the effective normal stress and the accumulation of the volumetric strain with the number of cycles. Moreover, the cyclic simple shear tests are simulated by the enhanced SIMSAND model by incorporating the stress reversal technique. Finally, a series of model pile tests under monotonic and cyclic loadings are simulated based on which the cone resistance of the piles is evaluated as well as the response of the soil surrounding the pile
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Siraty, A. "Behaviour of model foundations on sand". Thesis, University of South Wales, 1992. https://pure.southwales.ac.uk/en/studentthesis/behaviour-of-model-foundations-on-sand(0fe38501-fbc3-4a79-8b3f-44f7d6cdf721).html.
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The aim of the present research is to examine the behaviour of foundation/sand interaction under load at a pre-failure stage generally known as "Serviceability". The semi-full scale foundation used is a purpose designed bolted steel box, instrumented to measure contact stresses and displacements at selected points. Three types of foundation/sand interaction cases were examined, namely: smooth surface, rough surface and smooth embedded. The sand used was Leighton Buzzard, placed under controlled conditions in a 3.0m diameter by 3.0m deep concrete tank. The vertical and horizontal displacements of the sand were monitored using displacement transducers and inclinometers. The former were also used to monitor the deformation of the foundation. Stress measuring transducers were installed at the underside of the foundation to record the normal and shear stresses at the soil/structure interface. Density changes within the sand were measured before and after loading. Each test was controlled using a "Management" program. Raw data were recorded using a Data Logger which was interfaced with a micro computer. Finite Element analysis was used to model the foundation/soil behaviour and the testing environment. The variation of both displacements and stresses, once processed, was plotted with position. The results were then compared with experimental data using back analysis techniques. Various parameters were subsequently established and verified. The main findings of this investigation are: Contact stresses increase from zero to twin peak distributions positioned symmetrically about the centre line of the foundation. The variation of normal stress with depth is such that only residual stresses remain at a depth of z=2.0B. The inclusion of base roughness was found to mobilize the stresses and displacements in the sand within a boundary closer to the loaded foundation. The imposition of surcharge resulted mainly in increased magnitude of stresses and displacements while their variation with depth remained similar to those of the smooth surface condition. Both experimental and F.E. results indicated the existence of a zone referred to as the tensile zone, the depth and boundary of which depended on the characteristics of the foundation i.e. base roughness and depth of embedment.
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Monzón, A. Juan Carlos (Monzón Alvarado). "Review of CPT based design methods for estimating axial capacity of driven piles in siliceous sand". Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/34667.
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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2006.Includes bibliographical references (leaves 81-83).
The Cone Penetration Test has been used for more than 30 years for soil exploration purposes. Its similarities in mode of installation with driven piles provides the potential of linking key variables of pile design and performance, such as base resistance and shaft friction, to measured cone tip resistance. Large scale pile load tests, performed in the last two decades, have shown better agreement with recent CPT based design criteria, than with conventional American Petroleum Institute (API) earth pressure approach design guidelines. The CPT based design methods provide a more coherent framework for incorporating soil dilation, pile size effect, pile plugging during installation, and the friction at the pile-soil interface. A review, of four recent CPT based design methods and the API design guidelines, for estimating axial capacity of driven piles in siliceous sands was performed by comparing their predictive performance to six documented on-shore piles with load tests. First, a detailed site investigation based on CPT data was performed to validate the provided soil profile, and to evaluate the accuracy of the CPT readings to identify and classify soil strata.
(cont.) Three piles were selected for further study and axial capacity calculations. Three of the design methods, UWA-05, ICP-05 and NGI-05, prove to accurately predict axial pile capacities for on-shore short piles founded on sites where sand dominates. Analysis against a larger and more detailed database is required to validate their performance in multilayer soil profiles.
by Juan Carlos Monzón A.
M.Eng.
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Jacobson, Linnea, i Viktor Karlsson. "Design Model for Driven Concrete Piles According to Eurocode". Thesis, Linköpings universitet, Kommunikations- och transportsystem, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-118573.
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Pålning är en vanlig grundläggningsmetod för att överföra laster från överliggande konstruktioner genom svaga eller instabila jordlager till fasta jordlager eller berg. En typ av påle som ofta används är den slagna spetsburna betongpålen som slås ned genom till exempel lös lera till fast berg. 2011 trädde Eurokod in som gällande regelverk för dimensionering av bärverk. Införandet innebar förändringar i dimensionering av bland annat slagna spetsburna betongpålar. Företaget WSP i Norrköping har tidigare använt ett beräkningshjälpmedel för att få en uppfattning om en spetsburen betongpåles bärförmåga. Detta beräkningshjälpmedel blev i och med införandet av Eurokod inte längre giltigt. En önskan från WSP var att klargöra vad som gäller för dimensionering av spetsburna betongpålar enligt Eurokod och att ett nytt beräkningshjälpmedel skulle skapas om så var möjligt. När litteraturstudien för examensarbetet utfördes stod det klart att inget samlat dokument som beskrev alla delar av dimensionering av slagna spetsburna betongpålar fanns. Syftet med examensarbetet blev i och med det att sammanställa och tydliggöra gällande regelverk kring dimensionering av slagna spetsburna betongpålar. I den teoretiska referensramen sammanställs gällande regler och tillvägagångssätt för att utföra dimensioneringsberäkningar för en slagen spetsburen betongpåle. Det som sammanställts kan ses som ett förslag på hur dimensionering av en slagen spetsburen betongpåle kan genomföras. Resultatet visar att det är möjligt att skapa ett tillförlitligt beräkningsprogram som kan beräkna bärförmågan hos en spetsburen betongpåle enligt Eurokod. Vid jämförelsen av bärförmågan beräknad med det tidigare beräkningshjälpmedlet och det nya visade det sig att det nya ger en högre bärförmåga och framförallt ett noggrannare beräknat resultat.
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Sands, Timothy Bryan. "Interaction between model bored piles and swelling London clay". Thesis, University of Hertfordshire, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289605.
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Han, Jie. "An experimental and analytical study of the behavior of fiber-reinforced polymer piles and pile-sand interactions". Diss., Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/20296.
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Yotte, Sylvie. "Contribution a l'analyse theorique et experimentale du comportement d'un massif sous l'effet de sollicitations liees au foncage et au vibrofoncage". Nantes, 1988. http://www.theses.fr/1988NANT2025.
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Simulation du vibrofoncage d'un pieu dans un massif sableux, assimile a un demi-espace viscoelastique, par une methode semi-analytique, en decomposant le pieu en sources reparties; resolution, a partir des equations de propagation d'ondes, par la transformee de hankel, permettant d'etablir en un point les deplacements dus aux ondes de volume et de rayleigh. Etude experimentale sur un modele plan (modele de schneebeli) et sur un modele reduit fonce en cuve
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Alkroosh, Iyad Salim Jabor. "Modelling pile capacity and load-settlement behaviour of piles embedded in sand & mixed soils using artificial intelligence". Thesis, Curtin University, 2011. http://hdl.handle.net/20.500.11937/351.
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This thesis presents the development of numerical models which are intended to be used to predict the bearing capacity and the load-settlement behaviour of pile foundations embedded in sand and mixed soils. Two artificial intelligence techniques, the gene expression programming (GEP) and the artificial neural networks (ANNs), are used to develop the models. The GEP is a developed version of genetic programming (GP). Initially, the GEP is utilized to model the bearing capacity of the bored piles, concrete driven piles and steel driven piles. The use of the GEP is extended to model the load-settlement behaviour of the piles but achieved limited success. Alternatively, the ANNs have been employed to model the load-settlement behaviour of the piles.The GEP and the ANNs are numerical modelling techniques that depend on input data to determine the structure of the model and its unknown parameters. The GEP tries to mimic the natural evolution of organisms and the ANNs tries to imitate the functions of human brain and nerve system. The two techniques have been applied in the field of geotechnical engineering and found successful in solving many problems.The data used for developing the GEP and ANN models are collected from the literature and comprise a total of 50 bored pile load tests and 58 driven pile load tests (28 concrete pile load tests and 30 steel pile load tests) as well as CPT data. The bored piles have different sizes and round shapes, with diameters ranging from 320 to 1800 mm and lengths from 6 to 27 m. The driven piles also have different sizes and shapes (i.e. circular, square and hexagonal), with diameters ranging from 250 to 660 mm and lengths from 8 to 36 m. All the information of case records in the data source is reviewed to ensure the reliability of used data.The variables that are believed to have significant effect on the bearing capacity of pile foundations are considered. They include pile diameter, embedded length, weighted average cone point resistance within tip influence zone and weighted average cone point resistance and weighted average sleeve friction along shaft.The sleeve friction values are not available in the bored piles data, so the weighted average sleeve friction along shaft is excluded from bored piles models. The models output is the pile capacity (interpreted failure load).Additional input variables are included for modelling the load-settlement behaviour of piles. They include settlement, settlement increment and current state of loadsettlement. The output is the next state of load-settlement.The data are randomly divided into two statistically consistent sets, training set for model calibration and an independent validation set for model performance verification.The predictive ability of the developed GEP model is examined via comparing the performance of the model in training and validation sets. Two performance measures are used: the mean and the coefficient of correlation. The performance of the model was also verified through conducting sensitivity analysis which aimed to determine the response of the model to the variations in the values of each input variables providing the other input variables are constant. The accuracy of the GEP model was evaluated further by comparing its performance with number of currently adopted traditional CPT-based methods. For this purpose, several ranking criteria are used and whichever method scores best is given rank 1. The GEP models, for bored and driven piles, have shown good performance in training and validation sets with high coefficient of correlation between measured and predicted values and low mean values. The results of sensitivity analysis have revealed an incremental relationship between each of the input variables and the output, pile capacity. This agrees with what is available in the geotechnical knowledge and experimental data. The results of comparison with CPT-based methods have shown that the GEP models perform well.The GEP technique is also utilized to simulate the load-settlement behaviour of the piles. Several attempts have been carried out using different input settings. The results of the favoured attempt have shown that the GEP have achieved limited success in predicting the load-settlement behaviour of the piles. Alternatively, the ANN is considered and the sequential neural network is used for modelling the load-settlement behaviour of the piles.This type of network can account for the load-settlement interdependency and has the option to feedback internally the predicted output of the current state of loadsettlement to be used as input for the next state of load-settlement.Three ANN models are developed: a model for bored piles and two models for driven piles (a model for steel and a model for concrete piles). The predictive ability of the models is verified by comparing their predictions in training and validation sets with experimental data. Statistical measures including the coefficient of correlation and the mean are used to assess the performance of the ANN models in training and validation sets. The results have revealed that the predicted load-settlement curves by ANN models are in agreement with experimental data for both of training and validation sets. The results also indicate that the ANN models have achieved high coefficient of correlation and low mean values. This indicates that the ANN models can predict the load-settlement of the piles accurately.To examine the performance of the developed ANN models further, the prediction of the models in the validation set are compared with number of load-transfer methods. The comparison is carried out first visually by comparing the load-settlement curve obtained by the ANN models and the load transfer methods with experimental curves. Secondly, is numerically by calculating the coefficient of correlation and the mean absolute percentage error between the experimental data and the compared methods for each case record. The visual comparison has shown that the ANN models are in better agreement with the experimental data than the load transfer methods. The numerical comparison also has shown that the ANN models scored the highest coefficient of correlation and lowest mean absolute percentage error for all compared case records.The developed ANN models are coded into a simple and easily executable computer program.The output of this study is very useful for designers and also for researchers who wish to apply this methodology on other problems in Geotechnical Engineering. Moreover, the result of this study can be considered applicable worldwide because its input data is collected from different regions.
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Betru, Getachew. "The behaviour of model fluke anchors in sand". Thesis, Heriot-Watt University, 1995. http://hdl.handle.net/10399/1283.
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Werner, Bradley T. Haff Peter K. Haff Peter K. Tombrello Thomas A. "A physical model of wind-blown sand transport /". Diss., Pasadena, Calif. : California Institute of Technology, 1987. http://resolver.caltech.edu/CaltechETD:etd-08042008-114600.
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McCall, Amy Jean Taylor. "Full-Scale-Lateral-Load Test of a 1.2 m Diameter Drilled Shaft in Sand". BYU ScholarsArchive, 2006. https://scholarsarchive.byu.edu/etd/403.
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The soil-structure interaction models associated with laterally loaded deep foundations have typically been based on load tests involving relatively small diameter foundations. The lateral soil resistance for larger diameter foundations has been assumed to increase linearly with diameter; however, few, if any load tests have been performed to confirm this relationship. To better understand the lateral resistance of large diameter deep foundations in sand, a series of full scale, cyclic, lateral load tests were performed on two 1.2 m diameter drilled shafts and a 0.324 m diameter steel pipe pile in sand. Although the tests involve two different foundation types, the upper 2.4 m of the profile, which provides the majority of the lateral resistance, consists of sand compacted around both foundation types. Therefore, these test results make it possible to evaluate the effect of foundation diameter on lateral soil resistance. The drilled shafts were first loaded in one direction by reacting against a fifteen-pile group. Subsequently a load test was performed in the opposite direction by reacting against a 9-pile group. The soil profile below the 2.4 m-thick layer of compacted sand consisted of interbedded layers of sand and fine-grained soil. For the drilled shaft load tests, pile head deflection and applied load were measured by string potentiometers and load cells, respectively. Tilt was also measured as a function of depth with an inclinometer which was then used to calculate deflection and bending moment as a function of depth. For the pipe pile, deflection and applied load were also measured; however, bending moment was computed based on strain gauges readings along the length of the pile. The lateral response of the drilled shafts and pipe pile were modeled using the computer programs LPILE (Reese et al., 2000), SWM6.0 (Ashour et al., 2002), and FB-MultiPier Version 4.06 (Hoit et al., 2000). Comparisons were made between the measured and computed load-deflection curves as well as bending moment versus depth curves. Soil parameters in the computer programs were iteratively adjusted until a good match between measured and computed response of the 0.324 m pipe pile was obtained. This refined soil profile was then used to model the drilled shaft response. User-defined p-multipliers were selected to match the measured results with the calculated results. On average very good agreement was obtained between measured and computed response without resorting to p-multipliers greater than 1.0. These results suggest that a linear increase in lateral resistance with foundation diameter is appropriate. LPILE typically produced the best agreement with measured response although the other programs usually gave reasonable results as well. Cyclic loading generally reduced the lateral resistance of the drilled shafts and pile foundation by about 20%.
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Dapp, Steven Douglas. "Static Lateral Load Testing of Model Piles in Clay Soil Phase 1". DigitalCommons@USU, 2000. https://digitalcommons.usu.edu/etd/4544.
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This research project was done on behalf of the Utah Department of Transportation (UDOT). Model piles were subjected to static lateral loading in homogeneous, undisturbed clay with a known undrained shear strength. The dimensions of length, diameter, height from soil to applied load, and a pile stiffness parameter as was determined by dimensional analysis to be consistent will common full-scale steel pipe piles commonly used by UDOT. Bending moment profiles of the model pile were obtained for Lateral loads using foil type strain gages. Pile head deflection and soil response (p-y curves) were determined from these measured pile moment profiles.
Model pile test results were compared to predictions made by the computer design packages Florida Pier (a 3-D, nonlinear, finite element analysis program written at the University of Florida) and COM624P.
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Nguyen, Van-Tri. "Thermal and thermo-mechanical behavior of energy piles". Thesis, Paris Est, 2017. http://www.theses.fr/2017PESC1160/document.
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Le comportement thermique et thermo-mécanique des pieux énergétiques est étudié par plusieurs approches : mesures au laboratoire sur des éprouvettes de sol, modélisation physique en modèle réduit, expérimentations sur pieu en vraie grandeur, et calculs numériques/analytiques. D’abord, la conductivité thermique d’un loess à l’état non saturé est mesurée en fonction de la teneur en eau et de la succion. Les résultats montrent une relation univoque entre la conductivité thermique et la teneur en eau pendant un cycle d’humidification/séchage alors qu’une boucle d’hystérésis est observée pour la relation entre la conductivité thermique et la succion. Deuxièmement, des essais thermiques sont réalisés sur un pieu énergétique expérimental en vraie grandeur pour étudier le transfert thermique à l’échelle réelle. Troisièmement, une solution analytique est proposée pour simuler la conduction thermique d’un pieu énergétique vers le sol environnant pendant un chauffage. Les tâches mentionnées ci-dessus concernant le comportant thermique sont ensuite complétées par des études sur le comportement thermo-mécanique des pieux énergétiques. D’un côté, des expérimentations sont réalisées sur un modèle réduit de pieu installé dans un sable sec ou dans une argile saturée. Trente cycles thermiques, représentant trente cycles annuels, sont appliqués au pieu sous différentes charges axiales en tête. Les résultats montrent un tassement irréversible avec les cycles thermiques ; ce tassement est plus important sous une charge axiale plus grande. De plus, le tassement est plus marqué pendant les premiers cycles thermiques et devient négligeable pour les cycles suivants. De l’autre côté, les travaux expérimentaux sur le modèle réduit de pieu sont complétés par les calculs numériques utilisant la méthode des éléments finis. Cette approche est d’abord validée avec les résultats obtenus sur le pieu modèle avant d’être utilisée pour prédire les résultats des expérimentations en vraie grandeurThe thermal and thermo-mechanical behavior of energy piles is investigated by various approaches: laboratory measurement on small soil samples, physical modeling on small-scale pile, experiments on real-scale pile, and analytical/numerical calculations. First, the thermal conductivity of unsaturated loess is measured simultaneously with moisture content and suction. The results show a unique relationship between thermal conductivity and moisture content during a wetting/drying cycle while a clear hysteresis loop can be observed on the relationship between thermal conductivity and suction. Second, thermal tests are performed on a full-scale experimental energy pile to observe heat transfer at the real scale. Third, an analytical solution is proposed to simulate conductive heat transfer from an energy pile to the surrounding soil during heating. The above-mentioned tasks related to the thermal behavior are then completed by studies on the thermo-mechanical behavior of energy piles. On one hand, experiments are performed on a small-scale pile installed either in dry sand or in saturated clay. Thirty thermal cycles, representing thirty annual cycles, are applied to the pile under various constant pile head loads. The results show irreversible pile head settlement with thermal cycles; the settlement is higher at higher pile head load. In addition, the irreversible thermal settlement is the most significant during the first cycles; it becomes negligible at high number of cycles. On the other hand, the experimental work with small-scale pile is completed with numerical calculations by using the finite element method. This approach is first validated with the results on small-scale pile prior to be used to predict the results of full-scale experiments
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Louw, Hendrik. "Modelling horizontally loaded piles in the geotechnical centrifuge". Diss., University of Pretoria, 2020. http://hdl.handle.net/2263/73182.
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Pile foundations are extensively used to support various structures that are constructed in soft/loose soils, where shallow foundations would be considered ineffective due to low bearing capacities and large settlements. The design of these structures to accommodate lateral applied loads in particular, usually imposed by winds, water and earth pressures, has gained popularity over the past few decades. The behaviour of horizontally loaded piled foundations is a complex soil-structure interaction problem and is usually concerned with the relative stiffness between the pile and the surrounding soil, where the relative stiffness is a function of both the stiffness and properties of the pile and the stiffness of the soil.
Many design assumptions and methods used for pile foundations are based on the principles observed from metal piles. This raises the question of the validity and accuracy of assumptions and methods for the use of analysing and designing reinforced concrete piles, that exhibits highly non-linear material behaviour and changing pile properties after cracking. Due to the elastic behaviour of metal sections, these methods typically only focus on the soil component of the soil-structure interaction problem, only allowing changes and non-linear behaviour of the soil surrounding the pile to take place upon load application, mostly disregarding the behaviour and response of the pile itself.
The main purpose and objective of the study was to determine whether aluminium sections in a centrifuge could be used to realistically and sufficiently accurately model the monotonic and cyclic response of reinforced concrete piles subjected to lateral loading. This was observed though a number of tests conducted in a geotechnical centrifuge on scaled aluminium and reinforced concrete piles, subjected to both monotonic and cyclic loading.
After conducting the tests on both the scaled aluminium and reinforced concrete piles in the centrifuge it was concluded that aluminium sections cannot be used to accurately model and predict the lateral behaviour of reinforced concrete piles. Both the scaled aluminium and reinforced concrete piles proved to model the concept of laterally loaded piles quite well regarding bending at low loads. However, even at low lateral loads, the observed response of the scaled reinforced concrete was significantly different than that observed from the scaled aluminium pile. Furthermore, as the magnitude of the applied load and bending increased, the scaled reinforced concrete pile cracked, resulting in non-linear behaviour of the section under loading, which was not the case for the scaled aluminium pile that remained uncracked. This contributed to the difference in behaviour between the piles studied, therefore, the true material behaviour and failure mechanisms involved with reinforced concrete piles were not replicated by using a scaled aluminium pile section. The non-linear behaviour of the scaled reinforced concrete pile after cracking affected both the behaviour of the pile, as well as the response of the soil surrounding the pile, in contrast with the behaviour observed from the scaled aluminium pile.Dissertation (MEng)--University of Pretoria, 2020.
The Concrete Institute
Concrete Society of Southern Africa
WindAfrica project
Civil Engineering
MEng (Structural Engineering)
Unrestricted
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Dabeet, Antone E. "A practical model for load-unload-reload cycles on sand". Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/4082.
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The behaviour of sands during loading has been studied in great detail. However, little
work has been devoted to understanding the response of sands in unloading. Drained
triaxial tests indicate that, contrary to the expected elastic behaviour, sand often exhibit
contractive behaviour when unloaded. Undrained cyclic simple shear tests show that the
increase in pore water pressure generated during the unloading cycle often exceeds that
generated during loading. The tendency to contract upon unloading is important in
engineering practice as an increase in pore water pressure during earthquake loading
could result in liquefaction.
This research contributes to filling the gap in our understanding of soil behaviour in
unloading and subsequent reloading. The approach followed includes both theoretical
investigation and numerical implementation of experimental observations of stress
dilatancy in unload-reload loops. The theoretical investigation is done at the micromechanical
level. The numerical approach is developed from observations from drained
triaxial compression tests. The numerical implementation of yield in unloading uses
NorSand — a hardening plasticity model based on the critical state theory, and extends
upon previous understanding. The proposed model is calibrated to Erksak sand and then
used to predict the load-unload-reload behaviour of Fraser River sand. The trends
predicted from the theoretical and numerical approaches match the experimental
observations closely. Shear strength is not highly affected by unload-reload loops.
Conversely, volumetric changes as a result of unloading-reloading are dramatic.
Volumetric strains in unloading depend on the last value of stress ratio (q/p’) in the
previous loading. It appears that major changes in particles arrangement occur once peak
stress ratio is exceeded. The developed unload-reload model requires three additional
input parameters, which were correlated to the monotonic parameters, to represent
hardening in unloading and reloading and the effect of induced fabric changes on stress
dilatancy. The calibrated model gave accurate predictions for the results of triaxial tests
with load-unload-reload cycles on Fraser River sand.
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Nguyen, Tuong Quy. "A three dimensional model for vertical piles in sand". Thesis, 1991. http://spectrum.library.concordia.ca/4739/1/NN64756.pdf.
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