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Cuthbertson-Black, Robert. "The interaction between a flighted steel pipe pile and frozen sand." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ57528.pdf.
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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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Burali, d'Arezzo Francesca. "Installation effects due to pile surging in sand." Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.709370.
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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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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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Gui, Meen-Wah. "Centrifuge and numerical modelling of pile and penetrometer in sand." Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.361612.
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Wilson, Daniel W. "Soil-pile-superstructure interaction in liquefying sand and soft clay /." Davis, Calif. : Center for Geotechnical Modeling, Dept. of Civil and Environmental Engineering, University of California, Davis, 1998. http://cgm.engr.ucdavis.edu/download/html.
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Al-Defae, Asad Hafudh Humaish. "Seismic performance of pile-reinforced slopes." Thesis, University of Dundee, 2013. https://discovery.dundee.ac.uk/en/studentTheses/829dd554-a7e9-4c61-9206-01909793666c.
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Shallow embankment slopes are commonly used to support elements of transport infrastructure in seismic regions. In this thesis, the seismic performance of such slopes in non-liquefiable granular soils has been investigated and an extensive programme of centrifuge testing was conducted to quantify the improvements to seismic slope performance which can be achieved by installing a row of discretely spaced vertical precast concrete piles. This study focussed on permanent movement and dynamic response at different positions within the slope, especially at the crest, which would form key inputs into the aseismic design of supported infrastructure. In contrast to previous studies, the evolution of this behaviour under multiple sequential strong ground motions is studied through dynamic centrifuge modelling, analytical (sliding-block) and numerical (Finite Element) models. This thesis makes three major contributions. Firstly, an improved sliding-block (‘Newmark’) approach is developed for estimating permanent deformations of unreinforced slopes during preliminary design phases, in which the formulation of the yield acceleration is fully strain-dependent, incorporating the effects of both material hardening/softening and geometric hardening (re-grading). This is supported by the development of numerical (Finite Element) models which can additionally predict the settlement profile at the crest of the slope and also the dynamic ground motions at this point, for detailed seismic design were also developed. It is shown that these new models considerably outperform existing state-of-the art models which do not incorporate the geometric changes for the case of an earthquake on a virgin slope. It is further shown that only the improved models can correctly capture the behaviour under further earthquakes (e.g. strong aftershocks) and therefore can be used to determine the whole-life performance of a slope under a suite of representative ground motions that the slope may see during its design life, and allow improved estimates of the seismic performance of slopes beyond their design life. The finite element models can accurately replicate the settlement profile at the crest (important for highway or rail infrastructure) and quantify the dynamic motions which would be input to supported structures, though these were generally over-predicted. Secondly, the principles of physical modelling have been used to produce realistically damageable model piles using a new model reinforced concrete (both a designed section specifically detailed to carry the bending moments induced by the slipping soil mass and a nominally reinforced section with low moment capacity). This was used to investigate how piles can stabilise slopes under earthquake events and how the permanent deformation and the dynamic response of stabilised slope are strongly influenced by the pile spacing (S/B) especially at the minimum pile spacing (i.e. S/B=3.5). This is consistent with previous suggestions made for the optimal S/B ratio for encouraging soil arching between piles at maximum spacing both under monotonic conditions, and for numerical investigations of the seismic problem. These were supported by further centrifuge tests on conventional ‘elastic’ piles which were instrumented to measure seismic soil-pile interaction. The importance of reinforcement detailing was also highlighted, with the nominally reinforced section yielding early in the earthquake; the damaged piles subsequently only offer a small (though measureable) reduction in seismic slope performance compared to the unreinforced case. It was demonstrated that both permanent deformations at the slope crest (e.g. settlement) and dynamic ground motions at the crest can be significantly reduced as pile spacing reduced. Finally, a coupled P-y and elastic continuum approach for modelling soil-pile interaction has been used to develop a Newmark procedure applicable for pile-reinforced slopes. It was observed that the single pile resistance is mobilising at beginning of the earthquake’s time and it is strongly influenced by pile stiffness properties, pile spacing and the depth of the slip surface. It was observed also that the depth of the slip surface and pile spacing (S/B) play an important role in the determination of the permanent deformation of the slope. The results show great agreement to centrifuge test data in term of the permanent deformation (settlement at the crest of the slope) with slight differences between the measured (centrifuge) and calculated (this procedure) maximum bending moments.
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Su, Dong. "Centrifuge investigation on responses of sand deposit and sand-pile system under multi-directional earthquake loading /." View abstract or full-text, 2005. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202005%20SU.
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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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Walsh, J. Matthew. "Full-scale lateral load test of a 3x5 pile group in sand /." Diss., CLICK HERE for online access, 2005. http://contentdm.lib.byu.edu/ETD/image/etd955.pdf.
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Jebur, A. A. J. "An experimental and theoretical study of pile foundations embedded in sand soil." Thesis, Liverpool John Moores University, 2018. http://researchonline.ljmu.ac.uk/9211/.
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This study aimed to examine the load carrying capacity of model instrumented piles embedded in sand soil, and to develop and verify reliable, highly efficient predictive models to fully correlate the non-linear relationship of pile load-settlement behaviour using a new, self-tuning artificial intelligence (AI) approach. In addition, a new methodology has been developed, in which the most effective pile bearing capacity design parameters can be precisely determined. To achieve this, a series of comprehensive experimental pile load tests were carried out on precast concrete piles, steel closed-ended piles and steel open-ended piles, comprised of three slenderness ratios of 12, 17 and 25, using an innovative calibrated testing rig, designed and manufactured at Liverpool John Moores University. The model piles were tested in a large pile testing chamber at a range of different densities of sand; loose (18%), medium (51%) and dense (83%). It is worth noting that novel structural fibres were utilised and optimised for different volume fractions to enhance the mechanical performance of concrete piles. The obtained results revealed that the higher the values of the of the pile effective length, Lc (embedded length of pile), sand density, and the soil-pile angle of shearing resistance, the higher the axial load magnitudes to reach the yield limit. This can be attributed to the increase in the end bearing point and mobilised shaft resistance. In addition, the plastic mechanism occurring in the surrounding soil was identified as the leading cause for the presence of nonlinearity in the pile-load tests. Furthermore, a new enhanced self-tuning supervised Levenberg-Marquardt (LM) training algorithm, based on a MATLAB environment, was introduced and applied in this process. The proposed algorithm was trained after conducting a comprehensive statistical analysis, the key objectives being to identify and yield reliable information from the most effective input parameters, highlight the relative importance “Beta values” and the statistical significance “Sig values” of each model input variable (IV) on the model output. To assess the accuracy and the efficiency of the employed algorithm, different measuring performance indicators (MPI), suggested in the open literature, were utilised. Common statistical performance indexes, i.e., root mean square error (RMSE), Pearson’s moment correlation coefficient (p), coefficient of determination (R), and mean square error (MSE) for each model were determined. Based on the graphical and numerical comparisons between the experimental and predicted load-settlement values, the results revealed that the optimum models of the LM training algorithm fully characterised load-settlement response with remarkable agreement. Additionally, the proposed algorithm successfully outperformed the conventional approaches, demonstrating the feasibility of the current study. New design charts have been developed to calculate the individual contribution of the most significant pile bearing capacity design parameters “the earth pressure coefficient (K) and the bearing capacity factor (N )”. The improved approach takes into account the change in sand relative density, pile material type, and the pile slenderness ratios. It is therefore a significant improvement over most conventional design methods recommended in the existing design procedures, which do not consider the influence of the most significant parameters that govern the pile bearing capacity design process.
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Marsh, Robert Ashall. "Passive Earth pressures on a pile cap with a dense sand backfill /." Diss., CLICK HERE for online access, 2010. http://contentdm.lib.byu.edu/ETD/image/etd3356.pdf.
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Walsh, James Matthew. "Full-Scale Lateral Load Test of a 3x5 Pile Group in Sand." BYU ScholarsArchive, 2005. https://scholarsarchive.byu.edu/etd/605.
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Although it is well established that spacing of piles within a pile group influences the lateral load resistance of that group, additional research is needed to better understand trends for large pile groups (greater than three rows) and for groups in sand. A 15-pile group in a 3x5 configuration situated in sand was laterally loaded and data were collected to derive p-multipliers. A single pile separate from the 15-pile group was loaded for comparison. Results were compared to those of a similar test in clays. The load resisted by the single pile was greater than the average load resisted by each pile in the pile group. While the loads resisted by the first row of piles (i.e. the only row deflected away from all other rows of piles) were approximately equal to that resisted by the single pile, following rows resisted increasingly less load up through the fourth row. The fifth row consistently resisted more than the fourth row. The pile group in sand resisted much higher loads than did the pile group in clay. Maximum bending moments appeared largest in first row piles. For all deflection levels, first row moments seemed slightly smaller than those measured in the single pile. Maximum bending moments for the second through fifth rows appeared consistently lower than those of the first row at the same deflection. First row moments achieved in the group in sand appeared larger than those achieved in the group in clay at the same deflections, while bending moments normalized by associated loads appeared nearly equal regardless of soil type. Group effects became more influential at higher deflections, manifest by lower stiffness per pile. The single pile test was modeled using LPILE Plus, version 4.0. Soil parameters in LPILE were adjusted until a good match between measured and computed responses was obtained. This refined soil profile was then used to model the 15-pile group in GROUP, version 4.0. User-defined p-multipliers were selected to match GROUP calculated results with actual measured results. For the first loading cycle, p-multipliers were found to be 1.0, 0.5, 0.35, 0.3, and 0.4 for the first through fifth rows, respectively. For the tenth loading, p-multipliers were found to be 1.0, 0.6, 0.4, 0.37, and 0.4 for the first through fifth rows, respectively. Design curves suggested by Rollins et al. (2005) appear appropriate for Rows 1 and 2 while curves specified by AASHTO (2000) appear appropriate for subsequent rows.
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Marsh, Robert Ashall. "Passive Earth Pressures on a Pile Cap with a Dense Sand Backfill." BYU ScholarsArchive, 2009. https://scholarsarchive.byu.edu/etd/1958.
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Pile groups are often used to provide support for structures. Capping a pile group further adds to the system's resistance due to the passive earth pressure from surrounding backfill. While ultimate passive earth pressure under static loading conditions can be readily calculated using several different theories, the effects of cyclic and dynamic loading on the passive earth pressure response are less understood. Data derived from the full-scale testing of a pile cap system with a densely compacted sand backfill under static, cyclic, and dynamic loadings was analyzed with particular focus on soil pressures measured directly using pressure plates. Based on the testing and analyses, it was observed that under slow, cyclic loading, the backfill stiffness was relatively constant. Under faster, dynamic loading, the observed backfill stiffness decreased in a relatively linear fashion. During cyclic and dynamic loading, the pile cap gradually developed a residual offset from its initial position, accompanied by a reduction in backfill force. While the pile cap and backfill appeared to move integrally during static and cyclic loadings, during dynamic loading the backfill exhibited out-of-phase movement relative to the pile cap. Observed losses in backfill contact force were associated with both cyclic softening and dynamic out-of-phase effects. Force losses due to dynamic loading increased with increasing frequency (which corresponded to larger displacements). Losses due to dynamic loading were offset somewhat by increases in peak force due to damping. The increase in contact force due to damping was observed to be relatively proportional to increasing frequency. When quantifying passive earth forces with cyclic/dynamic losses without damping, the Mononobe-Okabe (M-O) equation with a 0.75 or 0.8 multiplier applied to the peak ground acceleration can be used to obtain a reasonable estimate of the force. When including increases in resistance due to damping, a 0.6 multiplier can similarly be used.
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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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Christensen, Dustin Shaun. "Full Scale Static Lateral Load Test of a 9 Pile Group in Sand." Diss., CLICK HERE for online access, 2006. http://contentdm.lib.byu.edu/ETD/image/etd1267.pdf.
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Valentine, Todd J. "Dynamic Testing of a Full-Scale Pile Cap with Dense Silty Sand Backfill." Diss., CLICK HERE for online access, 2007. http://contentdm.lib.byu.edu/ETD/image/etd2021.pdf.
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Runnels, Immanuel Kaleoonalani. "Dynamic Full-Scale Testing of a Pile Cap with Loose Silty Sand Backfill." Diss., CLICK HERE for online access, 2007. http://contentdm.lib.byu.edu/ETD/image/etd1854.pdf.
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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.
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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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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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Doreau, Malioche Jeanne. "Grain-scale investigation of sand-pile interface under axial loading conditions using x-ray tomography." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAI066/document.
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Cette thèse présente une étude expérimentale des mécanismes contrôlant la réponse macroscopique d’une interface sable-pieu sous sollicitations axiales monotones et cycliques. Une approche innovante associant la tomographie rayons X à des outils avancés d’analyses d’images en trois dimensions (3D) est utilisée dans le but d’extraire des informations à différentes échelles, notamment à l’échelle micro. L’analyse quantitative du comportement individuel des grains situés au voisinage du pieu fournit une collection de données 3D qui pourraient être utilisées pour la validation de modèles numériques ou théoriques.Une série de tests est réalisée sur un pieu instrumenté à pointe conique installé par vérinage monotone dans un échantillon dense de sable calcaire. Après l’installation, le pieu est soumis à un grand nombre de cycles axiaux contrôlés en déplacements (jusqu’à 2000 cycles), à contraintes constantes. Ces essais ont été conduits dans une mini chambre de calibration qui permet d’acquérir des tomographies rayons X à haute résolution après différentes étapes de chargement. Il est admis que le dispositif expérimental n’est pas représentatif des conditions d’essais sur pieux in-situ pour les raisons principales suivantes : le ratio entre le diamètre de la chambre le diamètre du pieu et le ratio entre le diamètre du pieu et la taille moyenne des grains sont bien inférieurs aux ratios recommandés dans la littérature afin de limiter les effets d’échelle. Par conséquent, les résultats obtenus dans ce travail ne peuvent et ne doivent pas être directement extrapolés pour le design de pieux réels. Cependant, un tel dispositif permet de reproduire qualitativement des tendances similaires à celles observées à l’échelle macro sur des essais à grande échelle et d’observer des mécanismes se déroulant à l’échelle micro.Les images 3D obtenues par reconstruction des tomographies rayons X sont utilisées afin d’identifier et de suivre l’évolution des grains individuels. Le champ cinématique complet en 3D est mesuré grâce à un code de corrélation d’images numériques 3D (DIC), « TomoWarp2 ». Des outils de traitement d’image sont également employés pour suivre les changements de porosité et la production de fines par broyage des grains à l’interface.Pendant la mise en place du pieu, plusieurs zones où les déplacements se concentrent sont identifiées. Une recirculation des grains le long du fût du pieu est mise en évidence. Globalement, le sable a un comportement dilatant à l’exception d’une fine couche (épaisseur d’environ 3 à 4·D50) autour du pieu où les fines sont produites. Pendant les cycles, la réponse macroscopique de l’interface montre une évolution en deux phases, avec une augmentation non négligeable de la résistance du fût dans la seconde phase. Pour ces deux phases, la mesure de la cinématique granulaire révèle un comportement du sol différent associé à une densification importante à l’interface. Dans la première phase, le sol se contracte radialement dans une zone de 4·D50 d’épaisseur. Ce phénomène est certainement dû au réarrangement granulaire mesuré par DIC. Dans la seconde phase, les grains de sables se déplacent difficilement et la densité à l’interface atteint un seuil pour lequel le frottement sur le pieu augmente de manière significative<br>This doctoral work presents an experimental investigation into the mechanisms governing the macroscopic response of sand-pile interface during monotonic installation and subsequent axial cyclic loading. An innovative approach combining x-ray tomography and advanced image analysis tools is employed to extract information at different scales, including the micro-scale. A quantitative analysis of the behavior of individual sand grains in the vicinity of the pile offers valuable three-dimensional (3D) data set against which theoretical or numerical approaches could be tested.A series of tests is run on an instrumented close-ended conical model pile installed by monotonic jacking in a dense calcareous sand sample. Following the installation, the model pile is submitted to a large number of axial displacement-controlled loading cycles (a few thousands cycles) under constant normal stress. The tests are performed in a mini-calibration chamber that allows the acquisition of high resolution x-ray images at different stages of the loading. The chamber is admittedly not representative of field pile testing conditions for the main following reasons: the calibration chamber-to-pile diameter ratio and the sand particle-to-pile diameter ratio are far below the ratios recommended in the literature to limit scale effects on the interface response. Consequently, the results presented in this work can not, and should not, be directly extrapolated to field pile design. Yet, such a setup is able to reproduce qualitatively trends that are similar to those obtained at the macro-scale on large-scale experiments and allows the observation of full-field mechanisms taking place at the micro-scale.3D images resulting from the reconstruction of the x-ray scans are used to identify and follow the evolution of individual sand grains. Full-kinematics are measured thanks to a 3D Digital image Correlation (DIC) code, “TomoWarp2”. Image processing tools are also employed to measure local porosity changes and the production of fines by grain crushing at the interface.During pile installation, different zones where grains displacements concentrate are identified. A recirculation of the grains alongside the pile is also observed. Globally, the sand mass exhibits a dilative behavior except within a relatively thin layer (about 3 to 4·D50 thickness) around the model pile where grain crushing occurs. During subsequent loading cycles, the macroscopic response of sand-pile interface shows a two-phases evolution, with a non negligible increase of shaft resistance in the latter phase. For these two phases, the measurement of grain kinematics reveals a different behavior of the sand mass associated with a significant densification at the interface. In the first phase, the sand mass contracts radially within a region of thickness 4·D50. This mechanism is likely due to inter-granular rearrangement as measure by DIC. In the second phase, sand grains hardly move and the sand mass reaches a threshold density for which the friction on the shaft starts to increase substantially
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Wong, Ming Hoi. "Investigation of capacity, interactions and failure criteria of jacked pile groups in sand by centrifuge modelling /." View abstract or full-text, 2004. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202004%20WONGM.
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Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2004.<br>Includes bibliographical references (leaves 146-151). Also available in electronic version. Access restricted to campus users.
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Sabry, Mohab. "Shaft resistance of a single vertical or batter pile in sand subjected to axial compression or uplift loading." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/MQ64056.pdf.
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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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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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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.
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Cummins, Colin R. "Behavior of a full-scale pile cap with loosely and densely compacted clean sand backfill under cyclic and dynamic loadings /." Diss., CLICK HERE for online access, 2009. http://contentdm.lib.byu.edu/ETD/image/etd2839.pdf.
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Cummins, Colin Reuben. "Behavior of a Full-Scale Pile Cap with Loosely and Densely Compacted Clean Sand Backfill under Cyclic and Dynamic Loadings." BYU ScholarsArchive, 2009. https://scholarsarchive.byu.edu/etd/1684.
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A series of lateral load tests were performed on a full-scale pile cap with three different backfill conditions, namely: with no backfill present, with densely compacted clean sand in place, and with loosely compacted clean sand in place. In addition to being displaced under a static loading, the pile cap was subjected to low frequency, small displacement loading cycles from load actuators and higher frequency, small displacement, dynamic loading cycles from an eccentric mass shaker. The passive earth pressure from the backfill was found to significantly increase the load capacity of the pile cap. At a displacement of about 46 mm, the loosely and densely compacted backfills increased the total resistance of the pile cap otherwise without backfill by 50% and 245%, respectively. The maximum passive earth pressure for the densely compacted backfill occurred at a displacement of approximately 50 mm, which corresponds to a displacement to pile cap height ratio of 0.03. Contrastingly passive earth pressure for the loosely compacted backfill occurred at a displacement of approximately 40 mm. Under low and high frequency cyclic loadings, the stiffness of the pile cap system increased with the presence of the backfill material. The loosely compacted backfill generally provided double the stiffness of the no backfill case. The densely compacted backfill generally provided double the stiffness of the loosely compacted sand, thus quadrupling the stiffness of the pile cap relative to the case with no backfill present. Under low frequency cyclic loadings, the damping ratio of the pile cap system decreased with cap displacement and with increasing stiffness of backfill material. After about 20 mm of pile cap displacement, the average damping ratio was about 18% with the looser backfill and about 24% for the denser backfill. Under higher frequency cyclic loadings, the damping ratio of the pile cap system was quite variable and appeared to vary with frequency. Damping ratios appear to peak in the vicinity of the natural frequency of the pile cap system for each backfill condition. On the whole, damping ratios tend to range between 10 and 30%, with an average of about 20% for the range of frequencies and displacement amplitudes occurring during the tests. The similar amount of damping for different ranges of frequency suggests that dynamic loadings do not appreciably increase the apparent resistance of the pile cap relative to slowly applied cyclic loadings.
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Yadak, Reza. "Comparing CPT Results and Numerical Method Investigations to Assess the Behaviour of Pile and Sand and Mixed Soil Using ABAQUS." Thesis, Curtin University, 2020. http://hdl.handle.net/20.500.11937/84165.
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The cone penetration test (CPT) is a method used to determine the geotechnical engineering properties of soils and delineating soil stratigraphy. This study demonstrates the expansion of numerical models using ABAQUS software, which are purposed to be used to predict the load-settlement and the ultimate bearing capacity behavior of pile foundations embedded in sand and mixed soil. This achieved by validating numerical results, using ABAQUS, and CPT site investigations.
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Lings, Martin L. "Contributions to the understanding of deep excavations in stiff clay and stiffness anisotropy also pile shaft friction and sand-steel interfaces." Thesis, University of Bristol, 2008. http://hdl.handle.net/1983/6fc1f459-b593-4b23-9059-9de25b8aae05.
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El, Haffar Ismat. "Physical modeling and study of the behavior of deep foundations of offshore wind turbines in sand." Thesis, Ecole centrale de Nantes, 2018. http://www.theses.fr/2018ECDN0021/document.
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La capacité axiale et latérale des pieux foncés dans du sable de Fontainebleau NE34 ont été étudié à l’aide d’essais sur modèles réduits centrifugés. L’effet de la méthode d’installation, de la densité et de la saturation du sable, du diamètre du pieu, de la géométrie de sa pointe (ouvert /fermé) et de sa rugosité sur la capacité axiale a été étudié. Une augmentation significative de la capacité en traction est observée dans les pieux foncés cycliquement, contrairement aux pieux foncés d’une manière monotone à 100 × g. La saturation du sable dense accélère la formation du bouchon lors de l'installation du pieu. L'augmentation de la rugosité du pieu et de la densité du sable accroissent significativement le frottement latéral des pieux testés. Dans tous les cas, les capacités de pieux sont comparées aux codes de dimensionnement des éoliennes offshore. Une étude paramétrique de l'effet de la méthode d'installation, de l'excentricité de la charge et de la saturation du sable sur la réponse latérale des pieux foncés est ensuite réalisée grâce à l'utilisation d'un pieu instrumentée. Le pieu est chargé d’une manière monotone puis un millier de cycles sont appliqués. Une nouvelle méthode a été développée pour la détermination des constantes d'intégration pour déterminer le profil de déplacement latéral du pieu. La méthode d'installation influence directement le comportement global (moment maximum et déplacement latéral) et local (courbes p-y) des pieux. L'effet de l'excentricité de la charge et de la saturation du sable sur le comportement des pieux est également présenté. Dans chaque cas, une comparaison avec les courbes p-y extraites du code DNVGL est réalisée<br>The axial and lateral capacity of piles jacked in Fontainebleau sand NE34 are studied using centrifuge modelling at 100×g. The effect of the installation method, sand density and saturation, pile diameter and pile tip geometry (open or closed-ended) and pile roughness on the axial capacity of piles are firstly studied. A significant increase in the tension capacity is observed in cyclically-jacked piles unlike piles monotonically jacked at 100×g. The saturation of dense sand accelerates plug formation during pile installation. The increase in pile roughness and sand density increases significantly the shaft resistance of the piles tested here. For all the cases, pile capacities are compared with the current design codes for offshore wind turbines. A parametric study of the effect of the installation method, load eccentricity and sand saturation on the lateral response of jacked piles is then realized using of an instrumented pile. The pile is loaded monotonically, then a thousand cycles are applied. A new methodology has been developed for determining of the constants needed in the integration procedure to identify the lateral displacement profile of the pile. The installation method influences directly the global (maximum moment and lateral displacement) and local behaviour (p-y curves) of the piles. The effect of the load eccentricity and sand saturation on the behaviour of the piles is also presented. In each case a comparison with the p-y curves extracted from the DNVGL code is realized
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TAKAGI, Kenji, 光夫 野津, Mitsuo NOZU та ін. "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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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-pieu<br>This 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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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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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.<br>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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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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GUERRA, Lara. "MODELLAZIONE FISICA DI PALI TRIVELLATI IN SABBIA." Doctoral thesis, Università degli studi di Ferrara, 2010. http://hdl.handle.net/11392/2388691.
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The dissertation deals with the modelling of the behaviour of bored pile,
embedded in a coarse grained soil, axially loaded in tension and
compression, with particular attention to the mobilization of the lateral
and the base capacities.
A series of almost 60 centrifuge tests has been carried out on free-headed
and close-ended rough model piles, instrumented and not, whose
dimensions varies from 8 mm to 32 mm in diameter and 160 mm to 320
mm in length. The tests have been carried out at various acceleration
levels between 30g and 160g, thus simulating a large series of prototype
dimensions. The “ideally non-displacement” model piles are embedded
in a very fine silica sand, called FF, pluvially deposed at a medium and a
high density.
To analyse the load direction effect on the mobilisation of the skin
friction, the results of tension tests are compared with those gathered in
compression at same state conditions.
A series of almost 150 direct shear constant normal stiffness tests, on
interface between FF sand and rigid aluminium plates of various surface
roughness has been performed.
All centrifuge and direct shear constant normal stiffness tests have been
performed at the ISMGEO laboratories (Istituto Sperimentale Modelli
Geotecnici in Seriate BG, Italy), which totally financed the experimental
program.
The conceptual framework of the physical modelling of bored pile
foundation in centrifuge is described in the first part of the thesis,
underlining the limitations mainly connected to the scale effects. The
experimental set up, the model piles dimensions and characteristics, the mechanical properties of the FF sand, the sample deposition technique,
the test instrumentations and procedures are also outlined.
The common empirical correlations for the prediction of the shaft
resistance are summarised and applied to the centrifuge test results; a
new formulation to evaluate the normal stress variation, acting on the pile
shaft at peak friction, is also proposed, which take into account for the
density of the sand.
The scale effects on the ultimate shaft resistance and on the correlated
settlement are analysed so as the displacement scaling law which has to
be applied on the interface behaviour to scale the settlement of model
pile to prototype scale.
The critical and ultimate base resistance of model non-displacement piles
loaded in centrifuge tests are evaluated using the most common practical
correlations. New formulations for the evaluation of the critical base
resistance from a cone penetration test and the sand state parameters are
presented.
The main conclusions derived from the centrifuge loading tests on model
piles, from the direct shear constant normal stiffness interface tests and
form some literature data, are summarised in the last chapter together
with future developments of the research.
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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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Yonan, Shafik J. "Pipe jacking forces in sand." Thesis, Loughborough University, 1993. https://dspace.lboro.ac.uk/2134/15343.
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In this research work, a comprehensive review of investigations into pipe jacking operations, and in particular the forces generated during the process, is presented. The factors affecting these forces were examined and their influence was studied in order to give a clear indication on the their magnitude and behaviour. A model scale testing facility, based on a 1.8m X 1.5m X 1.5m high steel tank, has been developed together with hydraulic jacking facilities and scale model pipes of 200mm diameter having both steel and concrete surfaces. In this facility the actual pipe jacking operation can be simulated, so that a study of the jacking forces could be made with the use of appropriate instrumentation techniques and computerised data recording. A series of tests was conducted to examine the influence of several parameters on the jacking forces, such as overcut ratio, type of soil, type of pipe surface, overburden pressure, and the rate of jacking. These parameters were in relation to the distance jacked. Two granular soils, uniformly graded Leighton Buzzard sand and well-graded River sand, were used as the material surrounding the pipeline, that is the material through which the pipes were jacked. Laboratory analysis on the soil materials was conducted and the relationship between results obtained from these tests and scale model testing were established. The interface friction between the surface of the pipeline and the surrounding soil was determined. The results show a peak in the jacking forces at the start of the jacking process, followed by a decrease and leveling off as the jacking continued. The graph is very similar to the stress/strain relationship of a typical granular soil. Both steel and concrete pipes were used in the tests to detennined the influence of pipe surface, and to a lesser degree pipe joint, characteristics. Higher forces were recorded for concrete pipes. The jacking rate was kept constant and consistent for all tests. It was found to have little effect on the magnitude of the jacking forces. The jacking forces were measured automatically using a computer. The results show a clear trend of increase in the jacking forces when the overburden pressure and jacking length were increased. Tests using different overcut ratios have indicated that a minimum jacking force might be achieved at a specific overcut ratio. The results of this research show that the jacking forces are influenced by a number of parameters. These include the overburden pressure, overcut ratio, pipe diameter, jacking length and the influence of the surrounding material. This is fully demonstrated by establishing a method of jacking forces prediction, termed herein the Loughborough Method.
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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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Osho, Adeyemi Joseph. "Effects of pipe orientation on sand transportation." Thesis, Cranfield University, 2013. http://dspace.lib.cranfield.ac.uk/handle/1826/8409.
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Sand transport in hilly terrain geometry is different and complex to understand compared to horizontal pipeline, due to the influence of the geometry that greatly affect multiphase flow and sand behaviour at the dip. The overall aim of this research work is to use experimental method to investigate the effects of multiphase flow behaviour on sand transport in a dip configuration. Experimental work was carried out to understand the complex dynamic mechanisms that exist during sand multiphase flow using 2” inch dip test facility with different inclination angles of ±24° and ±12° configurations. In order determine the multiphase flow parameters and sand flow regimes, extensive data were collected and analysed from continuous local measurement of instantaneous liquid hold up and sand hold up using conductivity rings. Significant observations were made during this study from which several conclusions were made. In the air–water test, three slug behaviours were observed at the dip: complete stratified flow downhill with slug initiation at dip; stratified flow (with energetic ripple) downhill with slug initiation and slug growth upward dip; and aerated slug downhill and slug growth at the dip. These behaviours are different from published work on this subject with low angle of inclination. The data analysis revealed that the two types of slug initiation mechanisms (wave growth and wave coalescence) observed are geometry specifics. The slug translational velocities (at the dip and uphill section) were used as criterion to determine the flow condition for each slug initiation mechanism at the dip. Significant observations were made during this study from which several conclusions were made. In the air–water test, three slug behaviours were observed at the dip: complete stratified flow downhill with slug initiation at dip; stratified flow (with energetic ripple) downhill with slug initiation and slug growth upward dip; and aerated slug downhill and slug growth at the dip. These behaviours are different from published work on this subject with low angle of inclination. The data analysis revealed that the two types of slug initiation mechanisms (wave growth and wave coalescence) observed are geometry specifics. The slug translational velocities (at the dip and uphill section) were used as criterion to determine the flow condition for each slug initiation mechanism at the dip. Five sand-water flow regimes (full suspension, streak, saltation, sand dune, and sand bed) were established by physical observation and data analysis. It was also observed that sand streaks were denser towards the central line of pipe bottom in the downhill pipe than that in uphill pipe. At downhill pipe section, there were sand gathering toward the central line of the pipe bottom. The characteristics of sand transportation at the dip section were found slightly different from downhill and uphill pipe for higher sand concentrations. When dense streak occurred at the downhill, the sand particles become dispersed at the dip. The minimum transport conditions (MTC) were determined at different sand concentration. The sand minimum transport condition in the dip section was found to be slightly lower than those in the downhill and uphill section. The minimum transport condition for a single phase water flow for the 24˚ dip. test section was slightly higher (with difference of about 0.1m/s) than that of the 12˚ at the downward and upward of the dip section at low sand concentration. In addition, local sand measurements using conductivity time series results at the downhill and uphill section showed the influence of sand concentration and flow condition on sand flow patterns. The air-water-sand results showed that sand deposits occurred in uphill section after sand transport at the downhill and dip sections. This was due to different flow regimes exhibited at the different pipe sections. The stratified (wavy) flow was the dominant flow in downhill pipe; therefore sand was observed transporting within the liquid film as thin streak for most of test conditions. The slug initiation at the dip section was observed to be a major factor that influences the sand behaviour. Sand particles in the slug unit (at the dip and uphill of the pipe) were observed to be entrained in the slug body once slug is initiated, thereby changing the force vector generating turbulence flow at the front of slug body. Once the sand particles entered the film zone of the slug unit, they immediately stopped moving forward due to the film velocity significantly lower than the slug body coupled with gravity effect. . Sand particles were found to be falling back while travelling with the water film at some conditions, until they were picked up by the next slug body. The results of this work provide a better understanding to the study of multiphase flow for pipeline design and most especially sand behaviour at the dip. The sand dune regime is identified distinctively using conductivity ring technique which would assist in determining the operating conditions that allow sand dune formation. The knowledge of flow condition at full suspension of sand is an important parameter to determine the erosion rate over the life span of the pipeline. Also, the quantity of sand bed and flow condition of sand settling at the dip is useful information for production chemist in order to determine the effectiveness of corrosion inhibitor at the bottom of the pipe. In conclusion, sand transport characteristics and MTC were strongly dependent on the gas-liquid flow regime and pipe geometry; and cannot be generalised on the superficial liquid and gas velocities of the transport fluid.
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GIRETTI, Daniela. "MODELLING OF PILED RAFT FOUNDATIONS IN SAND." Doctoral thesis, Università degli studi di Ferrara, 2010. http://hdl.handle.net/11392/2389285.
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A piled raft is a composite foundation in which the piles are used as
settlement reducers and they share, with the raft, the load from the
superstructure. The applied load is transferred from the raft to the
shallow soil and to the pile heads, and from the piles it is diffused
through the shaft and the base to deeper soil. The pile–raft and pile–pile
interactions represent the distinctive aspect of the piled raft foundations
since they modify the load–bearing behaviour of each foundation
component, compared to an analogous isolated element, thus determining
the overall foundation behaviour.
The main aim of this thesis is to highlight the effects of the raft–soil–pile
interactions on the resistance and stiffness of axially loaded piled raft
foundations in sand.
A series of centrifuge tests on models of rigid circular piled rafts in loose
saturated sand has been performed to this end, employing both non
displacement and displacement piles. The raft settlement and the load
transmitted to the pile heads and bases were monitored during the tests,
which also included unpiled raft and isolated pile tests.
The test results have been analysed in terms of bearing capacity and
stiffness; the former according to a load efficiency method, the latter by
comparing the values obtained from centrifuge tests with those evaluated
through a simplified analytical method.
ii Modelling of Piled Raft Foundations in Sand D. Giretti
In order to clarify the effect of the pressure transmitted by the raft to the
soil on the behaviour of a single capped pile, some of the centrifuge tests
were simulated via finite element numerical analyses, using an elasto–plastic strain hardening constitutive model for the sand. The geometry
and the dimensions of the numerical models corresponded to those of the
physical ones and the simulations were carried out applying an
accelerated gravitational field to the mesh.
The influence of a granular layer, interposed between the raft and the pile
heads, on the load transfer mechanism has also been analysed, through an
additional series of centrifuge tests which was performed on square rigid
raft models on displacement piles in dry dense sand.
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Conti, Claudio. "Small-scale physical modelling of piled foundations for offshore wind turbines application." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019.
Find full textAbstract:
Nowadays, finding alternative energy sources is becoming more and more important. Europe is particularly focusing on wind energy and in offshore wind energy especially. An issue concerning offshore wind energy which is gaining more and more attention is the noise emissions due to impact driven pile foundation. The noise caused by the installation process has been judged as “potentially dangerous for marine fauna” from the German Authorities.
This research thesis is part of a project which examines a viable alternative installation method for the displacement of pile foundations for offshore wind energy called pile jacking. This technology should be developed to be cost-efficient, flexibly scalable and to produce considerably reduced vibration and air pollution emissions during its placement in the sea bed. Jacked piles technology would eliminate almost any noise deriving from the hammer impact.
As most offshore piled foundations have been installed by impact driving technology, the question arises as to how piles with different the stiffness and the capacity , can otherwise be installed.
In order to delineate the significant variables affecting the load-bearing capacity and especially the ultimate uplift capacity of a pile in saturated sand, a small-scale test campaign in scale 1:30 has been performed at the Test Center for Support Structures in Hanover. The campaign was supervised by the Department for Support Structures of Fraunhofer IWES. A testing schedule comprising of 15 small-scale geotechnical physical experiments was conducted on open-ended piles to an embedded length of 75 cm using two method of pile installation: static jacking and impact driving.
The aim of this thesis is to obtain preliminary experimental data and set out the main features of this technology.
The results obtained by this study reveal that static jacking installation lead to higher resistances and is overall beneficial to the mechanical load bearing behavior of pile foundations.
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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 pieu<br>The 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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Wang, Dong. "Investigation of laterally loaded pile in sands using DEM." Thesis, University of Macau, 2012. http://umaclib3.umac.mo/record=b2586268.
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Kumar, Kavita. "Catalyseurs sans métaux nobles pour pile à combustible régénérative." Thesis, Poitiers, 2017. http://www.theses.fr/2017POIT2284/document.
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Le dihydrogène (H2) se présente comme le futur vecteur énergétique pour une économie basée sur des ressources propres et respectueuses de l'environnement. Il est le combustible idéal de la pile à combustible régénérative constituée de deux entités : un électrolyseur pour sa production, et une pile à combustible pour sa conversion directe en énergie électrique. Ce système présente l'avantage d'être compact et autonome. Cependant, l'amélioration de l'activité catalytique des matériaux, leur stabilité et l'élimination de métaux nobles dans leur composition sont nécessaires. Des catalyseurs bifonctionnels à base de métaux de transition associés au graphène ont alors été synthétisés. L'interaction oxyde-graphène a été étudiée sur un catalyseur Co3O4/NRGO. À faible teneur en cobalt, l'interaction entre les atomes de cobalt de l'oxyde et les atomes d'azote greffés sur les plans de graphène a été observée par voltammétrie cyclique. Cette interaction est responsable d'une diminution de la taille des nanoparticules de cobaltite et de l'activité de celles-ci vis-à-vis de la réaction de réduction du dioxygène (RRO). La substitution du cobalt par le nickel dans des structures de type spinelle (NiCo2O4/RGO) obtenu par voie solvothermale, a permis d'améliorer les performances électrocatalytiques vis-à-vis de la RRO et de la RDO. Ce matériau et un autre de type Fe-N-C préparé en collaboration avec un laboratoire de l'Université Technique de Berlin ont servi de cathode dans des études préliminaires réalisées en configuration pile à combustible alcaline à membrane échangeuse d'anion (SAFC)<br>Hydrogen, as an environmentally friendly future energy vector, is a non-toxic and convenient molecule for regenerative fuel cell, which connects two different technologies: an electrolyzer for H2 production, and a fuel cell for its direct conversion to electric energy. This kind of system possesses many advantages, such as lightness, compactness and more autonomy. However, improvement of activity and durability of electrode materials free from noble metals in their composition is needed. Thereby, bifunctional catalysts composed of transition metals deposited onto graphene-based materials were synthesized. The interaction between the metal atom of the oxide and the graphene doped heteroatom in the Co3O4/NRGO catalyst was investigated physicochemically. With a low cobalt loading, the interaction between cobalt and nitrogen was characterized by cyclic voltammetry, which revealed that it was responsible for decreasing the oxide nanoparticle size, as well as increasing the material activity towards the oxygen reduction reaction (ORR). The substitution of Co by Ni in the spinel structure (NiCo2O4/RGO) obtained by solvothermal synthesis, allowed the enhancement of the electrocatalytic performances towards the ORR and OER. Moreover, this catalyst as well as another material prepared in collaborative program with a lab from Technical University of Berlin were used as cathode in preliminary studies undertaken on solid alkaline fuel cell (SAFC)
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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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