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Chaudhry, Anjum Rashid. "Static pile-soil-pile interaction in offshore pile groups." Thesis, University of Oxford, 1994. http://ora.ox.ac.uk/objects/uuid:7b4c8d56-184f-4c8d-98c9-2d9c69a1ef55.
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This thesis is a theoretical study, using both finite element and boundary element methods, of the behaviour of single-piles and pile groups under vertical and lateral loading. It offers an improved understanding of the soil-structure interaction that occurs in pile groups, particularly closely spaced piles subjected to lateral loads. The potential of a two- dimensional idealisation of what is a three-dimensional problem is demonstrated by achieving real insight into the complex nature of pile-soil and pile-soil-pile interaction in pile groups. A new load transfer mechanism is presented for a rigid, axially loaded vertical pile. From this an improvement is then derived to the analytical solution for pile head settlement given by Randolph and Wroth (1978). The improved mechanism has the further merit that it can be applied also to solutions for flexible piles and pile groups. The improved analytical solution is further adapted in the development of two correcting layers specifically for vertically loaded piles to model infinite boundaries in the finite element model. The correcting layers help in establishing superiority of the finite element method over the boundary element method. To model pile-soil interaction, a purely cohesive interface element is developed and then validated by performing various two-dimensional test problems, including stability analysis of flat surface footings. Footing-soil interface tension is successfully modelled in this way - an outcome that entails a significant modification to the Hansen (1970) bearing capacity solution. Stability analysis is also carried out of conical footings using a three-dimensional finite element model: the results help to explain the applicability of the existing bearing capacity theories to conical footings. The ultimate lateral soil reaction is determined and various pile loading stages are investigated through parametric studies. Study of the stage immediately following pile installation (i.e. the consolidation stage) highlights the need to develop an effective stress analysis for laterally loaded piles. Pile-soil interaction is studied using the cohesive interface element presented earlier, which proves to be quite successful in smoothing out the stress discontinuities around the pile. A new material model for frictional soils is presented, and validated by using it to model an extension test: it captures well post-peak behaviour and takes care of the effects of dilation on the response of laterally loaded piles. Finally, mechanisms of interaction in closely spaced pile groups are studied. Simple analytical expressions are derived which quantify the effects of interaction. A new method of analysis is presented for single-piles and pile groups which offers a considerable degree of reliability without having to do either impossibly expensive full scale field tests or prohibitively expensive full three-dimensional analysis using the currently available computers.
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Lee, Cheol-Ju. "The influence of negative skin friction on piles and in pile groups." Thesis, University of Cambridge, 2001. https://www.repository.cam.ac.uk/handle/1810/272078.
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Satyamurthy, Ranjan. "Investigations of pile foundations in brownfields." ScholarWorks@UNO, 2005. http://louisdl.louislibraries.org/u?/NOD,219.
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Thesis (M.S.)--University of New Orleans, 2005.Title from electronic submission form. "A thesis ... in partial fulfillment of the requirements for the degree of Master of Science in the Department of Civil and Environmental Engineering"--Thesis t.p. Vita. Includes bibliographical references.
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Thavaraj, Thuraisamy. "Seismic analysis of pile foundations for bridges." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0017/NQ48728.pdf.
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Lee, Yoke Poh. "Cyclic analysis of laterally loaded pile foundations." Thesis, University of Glasgow, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.388555.
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Carbonari, Sandro. "Seismic response of structures on pile foundations." Doctoral thesis, Università Politecnica delle Marche, 2009. http://hdl.handle.net/11566/242284.
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Yilmaz, Beren. "An Anlaytical And Experimental Study On Piled Raft Foundations." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12611500/index.pdf.
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Two different concepts and design procedures namely settlement reducing piles and piled raft foundations have been studied independently in this thesis.
A laboratory study is conducted on model rafts with differing number of model settlement reducing piles. Pile length, pile diameter, type of soil and size of raft are kept constant and settlements are measured under sustained loading. Remolded
kaolin is consolidated under controlled stresses before tests are performed in model boxes. The tests are conducted under two sustained loadings of 75 kPa and 40 kPa. 0(raft), 16 and 49 number of piles are used. During the tests, all of the skin friction is mobilized. Several tests are conducted for each combination to see the variability. It is concluded that increasing the pile number beyond an optimum value is inefficient as far as the amount of settlement is considered. Also an analytical procedure has been followed to calculate settlements with increasing number of piles. In the second part of this thesis, finite element analyse have been performed on a piled raft foundation model, using Plaxis 3D Foundation Engineering software. This analyse are supported with analytical methods. The piled raft model is loaded with
450 kPa raft pressure. The studies are conducted in two sets in which different pile lengths are used25 m and 30 m respectively. The numbers of piles are increased from 63 to 143. All other parameters are kept constant. The results showed that again an optimum number of piles will be sufficient to reduce the settlement to the acceptable level. The analytical methods indicate a similar behavior. The comparison and results are presented in the study.
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Chu, Lok Man. "Centrifuge modeling of vessel impacts on bridge pile foundations /." View abstract or full-text, 2010. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202010%20CHU.
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Besar, Jusoh bin. "Load capacity of pile foundations : load test interpretation hypotheses." Thesis, Cardiff University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309047.
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Atves, Colleen E. "A Fuzzy Logic Analysis of Sustainable Concrete Pile Foundations." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1282670915.
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Horne, John C. "Effects of liquefaction-induced lateral spreading on pile foundations /." Thesis, Connect to this title online; UW restricted, 1996. http://hdl.handle.net/1773/10195.
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Arta, Mahmood Reza. "The behaviour of laterally loaded two-pile groups." Thesis, Durham University, 1992. http://etheses.dur.ac.uk/6122/.
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The response of piles and two-pile groups to lateral loading has been studied by field tests and computationally. Due to the lack of field test data and because of uncertainty concerning the pile/soil system it has been suggested that further experimental studies of pile groups under lateral loading should be undertaken. The research was conducted through a series of tests on vertical single piles and two-pile groups at various spacing and pile cap overhang heights, to identify the lateral stiffness, bending moment and axial force distribution. Attempts were also made to measure the in-situ total lateral soil pressure on the pile walls. Piles were designed to behave as "long" pile since most piles used in the U.K. are long and flexible. Piles were instrumented with strain gauges for measurement of bending moments and axial forces. Field tests were conducted in a sand trench using 4.0m long piles. A stiff steel pile cap was used to connect head of the two piles firmly together. Linear elastic back analyses of single pile tests were carried out to estimate the soil modulus profile with depth. Thereafter comparisons were made between the field test results on two-pile groups, published analyses and also a three dimensional finite element analysis. Tests results showed that the lateral stiffness of a two-pile groups tends towards a limit as spacing increases. A similar result was found from predictive and finite element analyses. The ratio between the maximum pile shaft bending moment and horizontal force varied between dry and wet season, being greater in the latter. The ratio between maximum reverse bending moment and horizontal load increased as the pile spacing and the overhang increased. Similar results results were found by finite element analysis. One of the main achievements in this research was the measurement of the axial forces in the vertical piles due to lateral loading. It was found that as the pile spacing increased and pile cap overhang height decreasd the peak axial forces per unit load decreased. Similar results were obtained by three dimensional finite element analysis.
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Leung, Yat Fai. "Foundation optimisation and its application to pile reuse." Thesis, University of Cambridge, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.608973.
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Bransby, Mark Fraser. "Piled foundations adjacent to surcharge loads." Thesis, University of Cambridge, 1995. https://www.repository.cam.ac.uk/handle/1810/251968.
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Al-Khazaali, Mohammed. "Soil-Pile, Pile Group Foundations and Pipeline Systems Interaction Behavior Extending Saturated and Unsaturated Soil Mechanics." Thesis, Université d'Ottawa / University of Ottawa, 2019. http://hdl.handle.net/10393/38843.
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Rapid growth in population along with positive trends in global economy over the past several decades has significantly contributed to an increased demand for various infrastructure needs worldwide. For this reason, the focus of this thesis has been directed towards extending the mechanics of unsaturated soils, which is an emerging geotechnical engineering field to investigate the behavior of two key infrastructure systems, namely pile foundations and energy pipeline systems. The mechanism of soil-pile foundations and soil-pipeline systems interaction behavior has several similarities.
Both these infrastructure facilities require comprehensive understanding of the soil-structure interaction mechanism. Reliable estimation of mechanical properties of both the soil and the soil-structure interface is required for the rational interpretation the load-displacement behavior of pile foundations and pipeline systems. Currently, the design of systems is predominantly based on design codes and guidelines that use empirical procedures or employ the principles of saturated soil mechanics. In many scenarios, pile foundations extend either totally or partly in unsaturated soils as the groundwater table level in many regions is at a greater depth. Such scenarios are commonly encountered in semi-arid and arid regions of the world. In addition, pipeline systems are typically buried at shallow depths in unsaturated soil strata, which are susceptible to wetting and drying, freezing and thawing cycles or both, due to seasonal environmental changes. Capillary stress or matric suction in the unsaturated zone increases the effective stress contribution towards the shear strength and stiffness of soil and soil-structure interface. Extending saturated soil mechanics to design or analyze such structures may lead to erroneous estimation of pile foundation carrying capacity or loads transferred on pipeline body from the surrounding unsaturated soil.
Experimental, analytical and numerical investigations were undertaken to study the behavior of single pile, pile group, and pipeline systems in saturated and unsaturated sands under static loading. The experimental program includes 40 single model pile and 2×2 pile group, and six prototype pipeline tests under saturated and unsaturated condition. The results of the experimental studies suggest that matric suction has significant contribution towards the mechanical behavior of both pile foundation and pipeline system.
The axial load carrying capacity of single pile and pile group increased approximately 2 to 2.5 times and the settlement reduced significantly compared to saturated condition. The influence of matric suction towards a single pile is significantly different in comparison to pile group behavior. The cumulative influence of matric suction and stress overlap of pile group behavior in sandy soils result in erroneous estimation of pile group capacity, if principles of saturated soil mechanics are extended. Group action plays major role in changing the moisture regime under the pile group leading to incompatible stress state condition in comparison to single pile behavior.
On the other hand, the peak axial load on the pipe is almost 2.5 folds greater in unsaturated sand that undergoes much less displacement in comparison to saturated condition. Such an increase in the external axial forces may jeopardize the integrity of energy pipeline systems and requires careful reevaluation of existing design models extending the principles of unsaturated soil mechanics. Two analytical design models to estimate the axial force exerted on pipeline body were proposed. The proposed models take account of matric suction effect and soil dilatancy and provide smooth transition from unsaturated to saturated condition. These models were developed since measurement of the unsaturated soil and interface shear strength and stiffness properties need extensive equipment that require services of trained professional, which are expensive and time consuming. The models utilize the saturated soil shear strength parameters and soil-water characteristic curve (SWCC) to predict the mechanical behavior of the structure in saturated and unsaturated cohesionless soils. The prototype pipeline experimental results were used to verify the proposed models. The predicted axial force on pipeline using the proposed models agrees well with the measured behavior under both saturated and unsaturated conditions.
Moreover, numerical techniques were proposed to investigate the behavior of pile foundation and pipeline system in saturated and unsaturated sand. The proposed methodology can be used with different commercially available software programs. Two finite element analysis programs were used in this study; namely, PLAXIS 2D (2012) to simulate soil-pile foundation behavior and SIGMA/W (2012) to simulate soil-pipeline system behavior. The proposed techniques require the information of unsaturated shear strength and stiffness, which can be derived from saturated soil properties and the SWCC. The model was verified using pile and pipeline test results from this study and other research studies from the published literature. There is a good agreement between the measured behavior and the predicted behavior for both the saturated and unsaturated conditions. The methodology was further extended to investigate the behavior of rigid and flexible pipelines buried in Indian Head till (IHT) during nearby soil excavation activity. The simulation results suggest that excavation can be extended safely without excessive deformation to several meters without the need for supporting system under unsaturated condition.
The studies summarized in the thesis provide evidence that the principles of saturated soil mechanics underestimate the pile foundations carrying capacity as well as the axial force exerted on pipelines in unsaturated soils. Such approaches lead to both uneconomical pile foundation and unsafe pipeline systems designs. For this reason, the pile and pile group carrying capacity and pipeline axial force should be estimated taking into account the influence of matric suction as well as the dilatancy of the compacted sand. The experimental studies, testing techniques along with the analyses of test results and the proposed analytical and numerical models are useful for better understanding the pile foundation and buried pipeline behaviors under both saturated and unsaturated conditions. The proposed analytical and finite element models are promising for applying the mechanics of unsaturated soils into conventional geotechnical engineering practice using simple methods.
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He, Liangcai. "Liquefaction-induced lateral spreading and its effects on pile foundations /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC IP addresses, 2005. http://wwwlib.umi.com/cr/ucsd/fullcit?p3208640.
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Forni, Fabio. "Investigating the axial response of pile foundations for offshore wind turbines." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017.
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I crescenti problemi legati ai cambiamenti climatici rendono l'impiego delle energie rinnovabili sempre più interessante.
In questa ottica, in Germania si sta pianificando di aumentare la produzione di energia pulita attraverso lo sfruttamento dell’energia eolica. Nuovi impianti di turbine eoliche sono previsti nel Mare del Nord in acque medio profonde (25-45m) dove la parte immersa della struttura della turbina eolica (chiamata sottostruttura) è spesso costituita da una struttura jacket (traliccio) o tripod (a treppiedi). Questo tipo di sottostrutture trasmettono principalmente carichi assiali alle fondazioni (in genere fondazioni su palo), e il carico a trazione è la forza che maggiormente ne influenza il dimensionamento.
Molte compagnie energetiche tedesche sono interessate a migliorare l’efficienza e i costi dei loro impianti eolici e, per questo, incaricano università ed istituti di ricerca (come il Fraunhofer IWES) per indagarne gli aspetti, come ad esempio il comportamento delle fondazioni offshore.
All’autore di questa tesi è stata data l’opportunità di studiare e lavorare al Fraunhofer IWES e perciò questa tesi tratterà del compramento di pali caricati assialmente e staticamente pensati per sottostrutture jacket o tripod per turbine eoliche.
Nello studio effettuato per questa tesi, i dati seprimentali, ottenuti da una campagna sperimentale condotta (in larga scala 1:10 1:5) su pali infissi in terreno sabbioso, sono confrontati attraverso l’impiego delle load-transfer curves (funzioni che descrivono il comportamento d’interfaccia palosuolo) usando sia un’approccio classico (fornito dal metodo di calcolo API Main Text) sia approcci più recenti (dati dai metodi di calcolo CPT).
Uno script Matlab creato appositamente dall’autore di questa tesi riesce ad implementare 11 diversi tipi di load-transfer curves. Il lavoro di tesi si conclude con un esempio pratico in grado di fornire un’idea di come questo script può essere usato nella progettazione.
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Al-Mousa, Ahmed A. "Investigation of pile foundations in the Al Hasa Area, Saudi Arabia." Thesis, University of Portsmouth, 2011. https://researchportal.port.ac.uk/portal/en/theses/investigation-of-pile-foundations-in-the-al-hasa-area-saudi-arabia(0f380983-84a0-402e-b627-604fa5eb150e).html.
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The Eastern Province of Saudi Arabia is experiencing a building boom of midsize and large scale construction projects. The expansion of these development projects is at risk due to the relatively unstudied soils of the area which pose serious problems for new foundations. As larger, heavier buildings are proposed for the region, an appropriate foundation system is needed for these problematic soils. One populated area of the Eastern Province is Al-Hasa, a densely populated oasis of agriculture and communities experiencing a boom in construction. The foundations of these new, heavier buildings are experiencing settlement due to the weak soils of the oasis. A comprehensive study of foundation solutions tailored to these specific conditions is now available. The main problem for construction in the Al-Hasa area of Saudi Arabia is the presence of clay layers,bwhich extend to a depth of 50 meters below the ground surface and are covered with a weak soil, such as Sabkha, cavities and expansive soil. Shallow foundations on this type of clay experience considerable settling problems throughout the life of the building. Therefore, to overcome this problem, a pile foundation is a logical alternative foundation system. Existing information on using pile foundations is examined and advanced through numerical analyses and analytical studies of the geotechnical characteristics and geological conditions of the area. A definitive understanding of the characteristics of Al-Hasa soils supports the need for a more successful foundations system. Field and laboratory tests were carried out in the Al-Hasa area to ascertain the characteristics of the soils in relation to known soil characteristics. Crucially, two case-studies of large building foundations, one a hotel, the other a hospital, are documented and the application of value-engineering to foundations is investigated. Four main applications result from this study. The first is a parametric study of the bearing capacity of single piles detailed for different sizes, depths, and loads in the unique soils of Al-Hasa. In the second, the settlement of single piles and pile groups, as well as a group action ratio, for different scenarios is researched for predictive applications. In the third, a formula for the critical depth of piles and liners is concluded for the local conditions. Finally the cost optimization of pile groups is analized in order to form a basis for pile design guidelines in the Al-Hasa area of Saudi Arabia. The software program ELPLA was utilized to calculate the optimum raft and pile rafts foundations for these problematic soils.
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Dithinde, Mahongo. "Characterisation of model uncertainty for reliability-based design of pile foundations." Thesis, Stellenbosch : Stellenbosch University, 2007. http://hdl.handle.net/10019.1/21612.
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Dissertation (PhD)--University of Stellenbosch, 2007.ENGLISH ABSTRACT: To keep pace with international trends, the introduction of geotechnical limit state design in South Africa is inevitable. To pave the way for implementation of limit state pile design in the country, the study quantifies model uncertainty in the classic static pile design formula under the Southern African geologic environment. The generated model uncertainty statistics are used to calibrate partial resistance factors in a reliability-based design framework. A series of pile performance predictions by the static formula are compared with measured performances. To capture the distinct soil types for the geologic region of Southern Africa as well as the local pile design and construction experience base, pile load tests and associated geotechnical data from the Southern African geologic environment are used. The methodology of collecting, compiling, and analyzing the pile load tests to derive the measured ultimate pile capacities is described. To facilitate the computation of the theoretical capacities, the site specific geotechnical data in the database are transformed to the desired engineering soil properties through well established empirical correlations. For a given pile test case, model uncertainty is presented in terms of a model factor computed as the ratio of the measured to the theoretical capacity, leading to n realisations of the model factor. To facilitate further interpretation and generalisation of the model factor realisation data, statistical analysis is carried out. The statistical analysis comprises of graphical representation by histograms, outliers detection and correction of erroneous values, and using the corrected data to compute the sample moments (mean, standard deviations, skewness and kurtosis) needed in reliability analysis. The analyses demonstrate that driven piles depict higher variability compared to bored piles irrespective of materials type. Furthermore, for a given pile installation method (driven or bored) the variability in non-cohesive materials is higher than that in cohesive materials. In addition to the above statistics, reliability analysis requires the theoretical probability distribution for the random variable under consideration. Accordingly it is demonstrated that the lognormal distribution is the most appropriate theoretical model for the model factor. Another key basis for reliability theory is the notion of randomness of the basic variables. To verify that the variation in the model factor is not explainable by deterministic variations in the database, an investigation of correlation of the model factor with underlying pile design parameters is carried out. It is shown that such correlation is generally weak. Correlation can have a significant impact on the calculated reliability index if not accounted for. Accordingly, the effects of the exhibited correlation is investigated through an approach based on regression theory in which systematic effects of design parameters are taken into account (generalised model factor). The model factor statistics from the conventional approach and those from the generalised model factor approach are used to determine reliability indexes implied by the current design practice. It is demonstrated that no significant improvement in values of the reliability indexes is gained by taking into account the effects of the weak correlation. The model factor statistics derived on the basis of the standard model factor approach are used to calibrate resistance factors. Four first order reliability methods are employed for the calibration of resistance factors. These include; the Mean Value First-Order Second Moment approach, an Approximate Mean Value First-Order Second Moment approach, the Advanced First-Order Second Moment approach using Excel spreadsheet, and the Advanced First-Order Second Moment approach (design point method). The resistance factors from the various calibration methods are presented for the target reliability index values of 2.0, 2.5, and 3.0. The analyses of the results demonstrate that for a given target reliability index, the resistance factors from the different methods are comparable. Furthermore, it is shown that for a given material type, the resistance factors are quite close irrespective of the pile installation method, suggesting differentiation of partial factors in terms of materials types only. Finally, resistance factors for use in probabilistic limit state pile design in South Africa are recommended.
AFRIKAANSE OPSOMMING: Ten einde in pas te bly met internasionale neigings, is dit onafwendbaar dat geotegniese limietstaat-ontwerp in Suid Afrika ingevoer word. Ter voorbereiding vir die plaaslike toepassing van limietstaatontwerp op heipale, kwantifiseer hierdie ondersoek onsekerheid rondom die model vir klassieke statiese heipaalontwerpformules in die Suid Afrikaanse geologiese omgewing. Die statistiek van modelonsekerheid wat gegenereer is, word gebruik om parsiële weerstandsfaktore in ’n betoubaarheid-gebasseerde ontwerpraamwerk te kalibreer. ’n Reeks voorspellings van die gedrag van heipale volgens die statiese formules word vergelyk met die gemete gedrag. Om die kenmerkende grond-tipes in die geologiese gebied van Suidelike Afrika sowel as die plaaslike ondervinding met heipaalontwerp en - konstruksie vas te lê, word heipaaltoetse en die gassosieerde geotegniese data vanuit hierdie geologiese omgewing gebruik. Die metodiek vir die versameling, saamstelling en analise van heipaaltoetse om uiterste kapasiteite daarvan te bepaal, word beskryf. Terreinspesifieke geotegniese data in die databasis word getransformeer na die vereisde ingenieurseienskappe volgens gevestigde empiriese korrelasies. Vir ’n gegewe heipaaltoets word modelonsekerheid weergegee in terme van ’n modelfaktor wat bereken word as die verhouding van die gemete tot die teoretiese kapasiteit waaruit n uitkomstes van die modelfaktor dus gegenereer word. Om verdere interpretasie en veralgemening van die modelfaktordata te vergemaklik, word ’n statistiese analise daarop uitgevoer. Die statistiese analise bestaan uit grafiese voorstellings deur middel van histogramme, uitkenning van uitskieters en verbetering van foutiewe waardes, waarna die statistiese momente (gemiddeld, standaardafwyking, skeefheid en kurtose) vir gebruik in betroubaarheidsanalise bereken word. Volgens die analises toon ingedrewe heipale ’n groter veranderlikheid as geboorde pale, ongeag die grondtipe. Verder is die veranderlikheid van heipale in kohesielose materiale hoër as in kohesiewe materiale, ongeag die installasiemetode (ingedrewe of geboor). Bykomend tot bogemelde statistiek, vereis betroubaarheidsanalise die teoretiese waarskynlikheidsdistribusie van die ewekansige veranderlike onder beskouing. Ooreenkomstig word illustreer dat die log-normale verspreiding die mees toepaslike verspreiding vir die modelfaktor is. ’n Verdere sleutelvereiste vir betroubaarheidsteorie is die mate van ewekansigheid van die basiese veranderlikes. Om te bepaal of die variasie in die modelfaktor nie deur deterministiese veranderlikes in die databasis verduidelik kan word nie, word ’n ondersoek na die korrelasie van die modelfaktor met onderliggende heipaalontwerpfaktore uitgevoer. Sodanige korrelasie is in die algemeen as laag bevind. Korrelasie kan ’n belangrike invloed op die berekende betroubaarheidsindeks hê indien dit nie in ag geneem word nie. Dienooreenkomstig word die effek van die getoonde korrelasie ondersoek met behulp van die metode van regressie-analise waarin sistematiese effekte van ontwerpparameters in berekening gebring word (veralgemeende modelfaktor). Die modelfaktorstatistiek wat volg uit die konvensionele benadering en dié van die veralgemeende benadering word gebruik om betroubaarheidsindekse te bepaal wat deur die bestaande ontwerppraktyk geïmpliseer word. Die bevinding is dat daar nie ’n noemenswaardige verbetering in die waardes van die betroubaarheidsindekse is wanneer die effek van die swak korrelasie in berekening gebring word nie. Die statistiek van die modelfaktor wat afgelei is volgens die standaardbenadering word gebruik om die weerstandsfaktore te kalibreer. Vier eerste-orde betroubaarheidsmetodes word gebruik om die weerstandsfaktore te kalibreer, naamlik die Gemiddelde Waarde Eerste-Orde Tweede Moment benadering, die Benaderde Gemiddelde Waarde Eerste-Orde Tweede Moment benadering, die Gevorderde Eerste-Orde Tweede Moment benadering waarin ’n Excel sigblad gebruik word en die Gevorderde Eerste-Orde Tweede Moment benadering (die ontwerppuntmetode). Die weerstandsfaktore vanaf die verskillende kalibrasiemetodes word weergegee vir waardes van 2.0, 2.5 en 3.0 van die teikenbetroubaarheidsindeks. ’n Ontleding van die resultate toon dat vir ’n gegewe teiken betroubaarheidsindeks die weerstandsfaktore vanaf die verskillende metodes vergelykbaar is. Verder word getoon dat vir ’n gegewe grondsoort, die weerstandsfaktore vir verskillende metodes van installasie van die heipaal nie veel verskil nie. Dit wil dus voorkom asof parsiële faktore in terme van die grondsoort uitgedruk kan word. Ten slotte word weerstandsfaktore vir gebruik in plastiese limietstaatontwerp van heipale in Suid Afrika aanbeveel.
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Haigh, Stuart Kenneth. "Effects of earthquake-induced liquefaction on pile foundations in sloping ground." Thesis, University of Cambridge, 2002. https://www.repository.cam.ac.uk/handle/1810/284009.
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This thesis details the results of an investigation into the behaviour of slopes of liquefiable sand under earthquake loading and the influence of these laterally spreading slopes on inclusions such as pile foundations passing through them. A study of the behaviour of these slopes has been carried out using the techniques of dynamic centrifuge modelling. Eight tests were carried out on laterally spreading slopes and a further five on slopes containing instrumented pile foundations. Each model was subjected to a sinusoidal input motion using a Stored Angular Momentum earthquake actuator, causing liquefaction of the sand and lateral spreading of the slope. Data from instruments measuring acceleration, fluid pressure, total stress and bending moment were logged during the earthquake and analysed to reveal information relating to the performance of these slopes during earthquakes. The experiments highlighted the importance of the dilation of liquefied soil to the behaviour of liquefiable slopes. Slope movements were limited by dilation during each cycle of the earthquake which prevented significant soil flow velocities from building up and large pressures were applied to piles from the liquefied soil owing to dilation of soil close to the pile foundation. It was shown that these large lateral forces were not wholly transmitted into bending moments due to the dynamic response of the piles, but this could be the cause of significant pile damage in other situations. It was also seen that present design methods are non-conservative for both the induced bending moments and the applied lateral loads. Further research is needed to develop better design guidance for this situation. The data from these experiments was compared with the results of a number of numerical models constructed during this work in order to simplify the prediction of the behaviour of these slopes. The displacements of the slopes were compared with those predicted using a Newmarkian sliding block approach modified to include the effects of excess pore pressures. This was shown to give reasonable agreement with centrifuge data, though it requires input of a measured or predicted time-history of excess pore pressure to calculate threshold accelerations.
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Pérez-Herreros, Jesús. "Dynamic soil-structure interaction of pile foundations : experimental and numerical study." Thesis, Ecole centrale de Nantes, 2020. http://www.theses.fr/2020ECDN0002.
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La réponse dynamique d’une structure supportée par des fondations profondes constitue un problème complexe d’Interaction Sol-Structure (ISS). Sous chargement sismique, les pieux sont soumis à la sollicitation imposée par le sol (interaction cinématique) et aux forces d’inertie transmises par la superstructure (interaction inertielle). Le dimensionnement des fondations profondes soumises à des sollicitations sismiques est souvent réalisé au moyen de méthodes conservatrices visant à assurer que les fondations ne soient pas endommagées. La plupart de ces méthodes considèrent le comportement de la fondation élastique linéaire et par conséquent la capacité de la fondation à dissiper de l’énergie du fait des mécanismes non-linéaires est négligée. Cette approche était justifiée dans le passé en raison du manque d’informations sur le comportement non-linéaire des fondations et de l’absence d’outils numériques adaptés. De telles limitations deviennent de plus en plus obsolètes, puisqu’un nombre pertinent de résultats expérimentaux et numériques sont maintenant disponibles, ainsi que de nouvelles méthodes de conception (Pecker et al. 2012). Dans cette thèse, le comportement des pieux isolés et des groupes de pieux sous chargement sismique est étudié avec une approche couplant l’expérimental et le numérique. Des essais dynamiques en centrifugeuse sont effectués avec un sol stratifié, plusieurs configurations de fondations et une série de séismes et sollicitations sinusoïdales. Des calculs non-linéaires aux éléments finis sont également effectués et comparés aux résultats expérimentaux afin d’étudier la capacité des modèles numériques à reproduire de manière satisfaisante la réponse non-linéaire des fondations. Un nouveau macroélément pour les groupes de pieux sous chargement sismique est proposé et validé numériquement. Le macroélément permet de prendre en compte les effets de groupe et leur variation avec la fréquence de sollicitation (interaction pieu-sol-pieu) ainsi que la non-linéarité développée dans le système. Le nouveau macroélément est enfin utilisé pour effectuer une analyse dynamique incrémentale (IDA) du pylône centrale d’un pont à haubansThe dynamic response of a structure supported by pile foundations is a complex Soil-Structure Interaction (SSI) problem. Under earthquake loading, the piles are subjected to loadings due to the deformation imposed by the soil (kinematic interaction) and to the inertial forces transmitted by the superstructure (inertial interaction). The design of deep foundations under seismic loadings is often carried out by means of conservative methods that aim to assure zero damage of the foundation. Most of these methods consider the behavior of the foundation as linear elastic. As a result, the capability of the foundation to dissipate energy during seismic loading due to nonlinear mechanisms is neglected. This approach was justified in the past due to the lack of information about the nonlinear behavior of foundations and the absence of adapted numerical tools. Such limitations are becoming more and more obsolete, as a relevant number of experimental and numerical results are now available as well as new design methods (Pecker et al. 2012). In this Ph.D, the behavior of single piles and pile groups under seismic loading is studied using both experiments and finite element calculations. Dynamic centrifuge tests are carried out with a multilayered soil profile, several foundation configurations and a series of earthquakes and sinusoidal base shakings. Nonlinear finite element calculations are also performed and compared to experimental results to investigate the ability of current computational models to satisfactorily reproduce the nonlinear response of foundations. A novel macroelement for pile group foundations under seismic loading is developed and numerically validated. It allows taking into account the group effects and their variation with the loading frequency (pile-soil-pile interaction) as well as the nonlinearity developed in the system. Finally, the macroelement model for pile groups is used to perform an Incremental Dynamic Analysis (IDA) of the main pylon of a cable-stayed bridge
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Qin, Hongyu. "Response of Pile Foundations due to Lateral Force and Soil Movements." Thesis, Griffith University, 2010. http://hdl.handle.net/10072/365515.
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This research has investigated the response of pile foundations subjected to lateral force applied directly to pile head and loadings arising from lateral soil movements of the surrounding ground. The behaviour of pile foundations subjected to lateral soil movements was studied through physical modelling with a specially designed testing apparatus. Laboratory experiments have been undertaken on a single pile embedded in progressive moving sand. A triangular loading block was used in the model tests to induce a progressive soil movement profile. Apart from eight general tests, sixteen tests were conducted on a single pile to examine the effects of the distance between the source where soil movements were induced and the pile location, the magnitude of axial load applied at pile head, the variation of loading block angle, varying combination of sliding and stable layer depths, and pile diameter on the responses of piles. The results of previously conducted pile tests with a uniform soil movement profile were compared with those of the current tests to examine the effect of soil movement profiles on the pile behaviour. Simple solutions were proposed for predicting the pile responses. They provided good estimate of the development of maximum bending moment and maximum shear force in the piles with soil movement. Importantly, the maximum bending moments induced by the soil movements were found to be linearly related to the maximum shear forces (sliding thrust), independent of the magnitude and depth of soil movement and soil movement profiles. Experiments have also been conducted on pile groups in progressive moving sand, including various pile group configurations and spacing. Both free-head and cappedhead fixity conditions have been considered. The findings show that the resistances of the piles to lateral soil movements significantly rely on their locations in a group, especially for piles arranged in a line parallel to the soil movement direction. The results of the pile group tests were compared with those of the single pile tests. Group factors were defined in terms of maximum bending moment and modulus of subgrade reaction to quantify the impact of group effect. The simple solutions developed were extended for predicting the response of individual piles in a group with soil movement. The static and cyclic responses of laterally loaded piles in cohesionless soils have been investigated as well. Guideline for estimating the design parameters for laterally loaded rigid piles in cohesionless soils were provided from extensive back calculation of measured responses of fifty-one pile tests. The elastic-plastic solutions presented by Guo (2008) were used in the back calculation. Simple expressions were presented for estimating the parameters used in the solutions. The reliability of the back calculation, the effects of the ratio of loading eccentricity to pile embedded length on the nonlinear pile response and lateral load capacity were investigated. Additionally, the apparatus was modified to apply cyclic lateral loading, with which a series of model tests were conducted on piles in dry sand under static and cyclic loadings. Analyses of the test results show that the cyclic load level has a greater impact on the pile behaviour than the number of cycles. It is noted that the gradient of the limiting force profile will decrease and the modulus of subgrade reaction will increase, after a number of unloading and reloading cycles. The induced maximum bending moment can be estimated from the applied lateral load, eccentricity of the load, and the depth at which the maximum bending moment occurs.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Engineering
Science, Environment, Engineering and Technology
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Saffari-Shooshtari, Nader. "Constant normal stiffness direct shear testing of chalk-concrete interfaces." Thesis, University of Surrey, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328819.
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Ahmed, Mahmoud Nasser Hussien. "Effects of Nonlinear Soil-Structure Interaction on Lateral Behavior of Pile Foundations." 京都大学 (Kyoto University), 2011. http://hdl.handle.net/2433/151949.
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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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Herbst, Mark Alan. "Impact of Mass Mixing on the Lateral Resistance of Driven-Pile Foundations." Diss., CLICK HERE for online access, 2008. http://contentdm.lib.byu.edu/ETD/image/etd2353.pdf.
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Jayasinghe, Laddu Bhagya. "Blast response and vulnerability assessment of piled foundations." Thesis, Queensland University of Technology, 2014. https://eprints.qut.edu.au/71184/1/Laddu%20Bhagya_Jayasinghe_Thesis.pdf.
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This research treated the response of pile foundations to blast loads. The influence of important parameters was investigated. The research techniques and the results will enable safer design of pile foundations that are vulnerable to blast loads.
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Ayfan, Emad. "Design method for axially loaded piled raft foundation with fully mobilised friction piles." Doctoral thesis, Universite Libre de Bruxelles, 2012. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209604.
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In the present work, a settlement-based method is proposed to design piled raft foundation. The proposed design method is found to be very efficient, economical and requires less calculation time. Simple software can be used to execute all the interactions and loop calculations.Unlike methods with numerical techniques, there are practically no limitations for the number of individual piles under the raft, size of the group and the group shape or layout. It can also be applied to piles with different length or piles that are located within multi-layered soils.
The raft is designed first according to the allowable settlement that is pre-defined by the structural requirements and with the necessary factor of safety. When raft suffers excessive settlement, then the load that causes excess raft settlement beyond the required limit is to be transferred to the fully mobilised frictional piles.
The fully mobilised shaft (with no end bearing) piles are designed with factor of safety close to unity since their function is only to reduce raft settlement and since the raft has an adequate bearing capacity.
Geometry of these piles is chosen to fully mobilise their shafts capacity with low settlement level in order to comply with load/settlement requirement and reduce raft settlement to the pre-defined level.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished
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Papagiannis, Michail. "WIND TURBINE FOUNDATIONS IN CLAY : Technical and economic considerations for proposals for wind turbine foundations." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-353397.
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This thesis approaches the problem of the cost-efficient wind turbine foundation on an onshore site of clayey soil characteristics. The given soil stratigraphy includes a layer of clay and two sands of different density. The characteristics of the soil and the water level that were used as input come from a site in Peloponissos, Greece. The applied wind, static and seismic loads on this study were resolved with the German DIN standards, and other related research and European standards. The safety factors were adjusted for wind turbines. For the pile solution, after the bearing and overturning adequacy against the horizontal and vertical loads was proven with the calculation of the DIN equations, then the model was inserted in the Pfahl program using DIN 4017 equations to calculate settlements. Firstly, a shallow foundation of various dimensions in the clay layer over the water level with all the necessary checks was considered. Afterward, a deep foundation solution of a single bored pile, with reinforcement steel casing, of various diameters was investigated. The different foundation solutions were assessed and compared on a technical and economic basis. As a conclusion, the 0.70 meter diameter single pile was chosen as the best solution because it needs only a few days for construction, and it is the most cost-efficient. The chosen circular footing was of a diameter of 10 meters and 1.5 meter raft thickness, but proved unfeasible because of high excavations costs. The checks on the DIN standards and Eurocode that set the boundaries for the design in the two cases were recognised and possible future work goals were discussed.
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Ng, Tsz Man. "Optimization of pile group foundations in non-linear soil using hybrid genetic algorithms /." View abstract or full-text, 2006. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202006%20NG.
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Miner, Dustin David. "The Effect of Flowable Fill on the Lateral Resistance of Driven-Pile Foundations." Diss., CLICK HERE for online access, 2009. http://contentdm.lib.byu.edu/ETD/image/etd3308.pdf.
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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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Zhou, Jialin. "Performance of Full Scale Tests of Piles in Different Soil Conditions." Thesis, Griffith University, 2018. http://hdl.handle.net/10072/381531.
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With the soaring requirement for building space in metropolises, high-rise buildings are becoming increasingly popular. Pile foundations can resist more loading through end bearing and friction resistance than can shallow foundations; hence, the use of pile foundations is more common. As a structural element that transfers the loads from upper structures into the soil layers, piles can be categorised into precast piles and cast-in-situ piles. As a result of their numerous advantages—such as convenience of construction without considering the transfer of piles, cost and schedule of construction—bored piles are the most accepted type of piles in construction projects...Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Eng & Built Env
Science, Environment, Engineering and Technology
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Yuksekol, Umit Taner. "A Simple Assessment Of Lateral Pier Response Of Standard Highway Bridges On Pile Foundations." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/3/12608135/index.pdf.
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Group of piles are widely used deep foundation systems to resist lateral and vertical loads. Seismic and static performance of pile groups mostly depend on soil type, pile spacing and pier rigidity.
Not many pile lateral load tests have been performed due to high costs. Advanced and complex analytical methods were developed over the years to assess nonlinear lateral pile response. This research is conducted aiming at developing a practical analysis method to verify the lateral performance of pile groups and its effect on overall response of bridge utilizing the available pile lateral load test data. Empirical constants derived from evaluation of lateral load tests are used in a simple formulation to define the nonlinear behavior of the pile-soil system. An analysis guideline is established to model the nonlinear soil-bridge interaction by the help of a general purpose structural analysis program comprising recommendations for various cases. Results of the proposed method is compared to the results of industry accepted advanced methods using response spectrum and nonlinear time history analyses to assess the suitability of this new application. According to the analysis results, proposed simple method can be used as an effective analysis tool for the determination of response of the superstructure.
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Jardine, Richard. "Investigations of pile-soil behaviour, with special reference to the foundations of offshore structures." Thesis, Imperial College London, 1985. http://hdl.handle.net/10044/1/8519.
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Gohl, W. Blair. "Response of pile foundations to simulated earthquake loading : experimental and analytical results volume I." Thesis, University of British Columbia, 1991. http://hdl.handle.net/2429/30882.
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The analysis of the dynamic response of pile foundations to earthquake shaking is a complex problem and has been treated using concepts developed from the theory of elasticity, applicable to low level shaking, and to models incorporating non-linear soil response appropriate for stronger shaking intensities. A review of available field reports indicates that due to the lack of complete instrumental recordings describing the response of full scale pile foundations to earthquake loading, the above analysis techniques are in large measure unchecked.
To provide a reliable data base suitable for checking various models of dynamic pile foundation response, a series of small scale model tests on single piles and pile groups embedded in dry sand foundations were carried out on shaking tables at the University of British Columbia. A similar series of tests were carried out using a geotechnical centrifuge equipped with a base motion actuator located at the California Institute of Technology. Under the centrifugal forces acting on the model, full scale stress conditions are simulated in the sand foundation. Since soil behaviour is stress level dependent, the centrifuge tests are considered to provide a more realistic simulation of full scale pile foundation behaviour. Both the shake table and centrifuge single pile tests were carried out using both sinusoidal and random earthquake input motions over a range of shaking intensities. From the data, details of soil-pile interaction were elucidated. This provided a basis for improvement in methods of estimating required input parameters used in the dynamic analysis of pile foundations.
Prior to each test, shear wave velocity measurements were made throughout the prepared
sand foundations using piezoceramic bender elements. This technique has proved
particularly useful in the centrifuge environment since the bender element source and receivers could be triggered remotely from off the centrifuge arm while the model was in flight. The shear wave velocity data were used to compute small strain, elastic shear moduli in the soil which have been found to be in close agreement with predictions made using an equation proposed by Hardin and Black (1968). Elastic compression wave velocities
were also identified from the bender element responses recorded during the shake table tests.
The single pile tests demonstrated that significant non-linearity and strain softening occurs in near field soil response, which is responsible for reductions in fundamental vibration frequency and pile head stiffness parameters with increasing amplitudes of lateral pile vibration. An analysis technique developed to estimate average effective strains around a single pile leads to predictions of large modulus reduction around the pile, depending on the amplitude of pile vibration.
Soil reaction pressures (p) due to relative horizontal movement between the soil and the pile (y) were deduced from the test data for various cycles of shaking, or so-called p-y curves. The cyclic p-y curves developed show clearly the non-linear, hysteretic near field response near the pile head. Approximately linear elastic p-y response occurs at greater depth. Backbone p-y curves computed using procedures recommended by the American Petroleum Institute (API) are in poor agreement with the experimental shake table and centrifuge measurements. Material damping inferred from the area within the p-y hysteresis loops increases, in general, with increasing pile deflection level. The experimental
p-y hysteresis loops were reliably simulated using a Ramberg-Osgood backbone curve and the Masing criterion to model unload-reload response.
Comparing the flexural response observed on single piles during the shake table and centrifuge tests, the depth of maximum bending moment relative to the pile diameter has been observed to be greater in the shake table tests. This can be anticipated from
the laws of model similitude. Cyclic p-y curves developed from the shake table and centrifuge tests also show substantial differences, with the shake table p-y curves being stiffer than predicted using the API procedures, while the opposite behaviour was found in the high stress, centrifuge environment. Damping in the low stress level environment of the shake table has been found to be greater than under full scale stress conditions in the centrifuge.
Two-pile tests, where the piles have been oriented inline, offline or at 45 degrees to the direction of shaking, indicate that pile to pile interaction is very strong for inline and 45 degree shaking, and is relatively minor for offline shaking. Interaction effects observed under low and high intensities of shaking die off with increasing pile separation distance at a quicker rate than predicted using elastic interaction theory. Interaction effects for inline and offline cyclic loading may be neglected for centre to centre pile spacings of about six and three pile diameters, respectively. For close pile separations during inline shaking, elastic theory underpredicts the extent of interaction. Similar conclusions were reached from the shake table and centrifuge tests conducted. Based on the experimental data and data available from the literature, modifications to elastic pile interaction coefficients have been suggested.
Predictions of single pile response to earthquake shaking have been made using an uncoupled, sub- structure approach incorporating non-linear pile head springs and equivalent
viscous dashpots (foundation compliances) derived from the test data. The foundation
compliances account for the deflection level dependent stiffness and damping characteristics
of the below ground soil-pile system. The measured free field surface motions have been used as the input excitation. Agreement between computed and measured pile responses was found to be excellent. A fully coupled analysis using the commercially available program SPASM8, where the below ground portions of the pile are directly
considered in the numerical discretization of the problem has also been used. Interaction
between the soil and vibrating ground is accounted for using a Kelvin-Voight model which includes non-linear Winkler springs and equivalent viscous dashpots to simulate radiation damping. Free field ground motions deduced from an independent free field response analysis using the computer program SHAKE are applied to the free field end of the soil-pile interaction elements. Using this full coupled model, the possible effects of kinematic interaction are accounted for. Results from the analysis show that SPASM8 underpredicts pile flexural response. A key difficulty in using an analysis of this kind is the accurate determination of free field input motions to be used along the embedded length of the pile.
A computer program, PGDYNA, has been developed to analyse the uncoupled response
of a superstructure supported by a group of foundation piles, taking into account non-linearity of the pile head compliances and the effects of pile group interaction. Interaction
factors developed from the experimental test program were used to calculate deflection level dependent pile head stiffnesses. Preliminary testing of the program indicates
that use of the free field surface motions as input, neglecting the effects of kinematic interaction, leads to an overestimate of pile group response.Applied Science, Faculty of
Civil Engineering, Department of
Graduate
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Bohn, Cécilia. "Serviceability and safety in the design of rigid inclusions and combined pile-raft foundations." Thesis, Paris Est, 2015. http://www.theses.fr/2015PEST1096/document.
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Les inclusions rigides sont un concept récent développé dans le prolongement des fondations mixtes, avec un matelas de transfert de charges entre les colonnes et la structure. Des méthodes de calculs et des concepts de sécurité existent pour ces systèmes combinés, notamment en France où le module pressiométrique mesuré et les recommandations ASIRI (IREX 2012) pour les inclusions rigides sont utilisés. Le dimensionnement classique des pieux basé sur une simple vérification de la portance des colonnes isolées ne peut pas être appliqué à ces systèmes combinés. Les tassements peuvent être plus importants du fait de la part significative de charge reprise par le sol. Le présent travail est une contribution au développement des méthodes de calcul et de dimensionnement en déplacement (préconisé par l'Eurocode 7, EN 1997-1 2004) pour les systèmes combinés sous charge verticale, en particulier au niveau international où des mesures in situ de module de sol ne sont généralement pas disponibles. Les éventuelles particularités de ces systèmes, notamment la sensibilité de colonnes non renforcées de petit diamètre, devaient également être examinées. La méthode de transfert de charge (“load transfer method”, LTM) est identifiée comme un outil d'ingénieur particulièrement adapté au calcul des systèmes combinés présentant une géométrie relativement simple. L'interaction sol-colonne en frottement et en pointe est définie par des courbes de transfert de charge (ou courbes “t-z” et “q-z”). Les méthodes en milieu continu comme la méthode des éléments finis sont à réserver en général aux cas complexes. Le comportement non-linéaire des semelles est examiné sur la base de mesures obtenues dans la littérature. Cette étude aboutit à la proposition d'une courbe charge-tassement hyperbolique pour les semelles. Cette courbe de mobilisation est définie de sorte qu'il y ait concordance avec la méthode linéaire habituelle pour un tiers de la charge ultime de la semelle. Le comportement de pieux isolés est étudié avec de nombreux essais de chargement instrumentés et non-instrumentés pour différents types de pieux et de sol. Une alternative aux courbes de transfert de charge selon Frank et Zhao (1982), basées sur le module pressiométrique, est recherchée. Des courbes de transfert de charge de type racine cubique et hyperbolique sont proposées pour tous types de pieux et de sol. La raideur des courbes proposées dépend d'une bonne estimation des valeurs ultimes de frottement et de résistance de pointe. Au contraire, la raideur initiale des courbes de Frank et Zhao est entièrement définie par le module pressiométrique, ce qui permet d'éviter des erreurs en termes de raideur. Les courbes de mobilisation proposées pour les fondations superficielles et pour les pieux sont combinées et étendues au cas des systèmes combinés. Cette méthode est implémentée comme option LTM dans le programme KID (Keller company 2015). Les prévisions avec le modèle proposé sont en très bonne adéquation avec les mesures effectuées sur 3 sites documentés dans la littérature. Une étude paramétrique montre une transition continue entre la fondation mixte et les inclusions rigides et une possibilité d'optimisation avec une diminution significative des efforts dans les colonnes et dans la fondation superficielle si un matelas est utilisé. En complément, une comparaison avec des calculs en éléments finis en 3D dans un cas théorique de semelle sur colonnes confirme que la méthode de transfert de charge développée est très performante pour des géométries simples. Une analyse de sensibilité est effectuée avec des modèles éléments finis axisymmétriques et 3D avec Plaxis (2013, 2014). Les imperfections géométriques ont principalement une incidence sur l'intégrité structurelle des colonnes non-armées de faible diamètre. Cependant, ces effets sont atténués dans les systèmes combinés en comparaison avec la colonne isolée du fait des possibilités de redistribution des charges dans le systèmeRigid inclusions represent a further development of combined pile-raft foundations, comprising a load transfer platform between the columns and the structure. Calculation methods and design concepts are available for such combined systems in particular in France, based on measured pressuremeter modulus values and on the French recommendations ASIRI for rigid inclusions (IREX 2012). The conventional pile design consisting only of a bearing capacity check for the individual column cannot be applied to such combined systems. The expected settlements may be larger due to a significant load proportion supported by the soil. The present work contributes to the development of displacement-based calculation methods (advocated by the Eurocode 7, EN 1997-1 2004) and design methods for combined systems under vertical loads, in particular on an international level where in general no in situ soil modulus values are measured. Possible particularities of such systems, like the sensitivity of unreinforced small-diameter columns, also had to be investigated. The load transfer method (LTM) is identified as a straightforward engineering tool for the calculation of combined systems with relatively simple geometries. The soil-column interaction in terms of skin friction and tip resistance is described by deformation-dependent load transfer curves (or “t-z” and “q-z” curves). Continuum methods like the finite element method should be preferred only for complex cases in general. The non-linear load-settlement behaviour of single footings up to failure is analysed based on measurements given in the literature. This yields the proposal of a hyperbolic load-settlement curve for footings. This mobilization curve is defined in a way to match the linear usual method for one third of the footing ultimate load. The behaviour of single piles is investigated based on numerous available instrumented and non-instrumented pile load tests with different pile and soil types. A reliable alternative to the load transfer curves after Frank and Zhao (1982), which are based on the pressuremeter modulus, is sought. Cubic root and hyperbolic axial load transfer curves are proposed for all pile and ground types. The stiffness accuracy of the proposed curves depends on an accurate estimation of the ultimate skin friction and tip resistance values. On the contrary, the initial stiffness of the Frank and Zhao curves is fully described by the pressuremeter modulus, avoiding thus errors in the stiffness. The proposed mobilization curves for the shallow and pile foundation behaviours are combined and extended for all combined systems. The proposed method is implemented as the LTM option into the software KID (Keller company 2015). The prediction with the developed model matches very well the measurements made for 3 different cases from the literature. A parametric study shows a smooth transition between the combined pile-raft foundation case and the rigid inclusion case and a potential for optimisation with a significant reduction of the internal forces in the columns and in the rigid slab when a load transfer platform is used. In addition, a comparison with 3D finite element calculations for a theoretical footing case with columns confirms that the developed load transfer method is very reliable for simple geometries. Sensitivity investigations using the axisymmetric and 3D finite element method with Plaxis (2013, 2014) are performed. Geometrical imperfections impact mainly the structural integrity of small-diameter unreinforced columns. However, these effects are reduced in combined systems compared to the single column case due to the possibility of redistribution of the loads within the system
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Adsero, Matthew E. "Effect of jet grouting on the lateral resistance of soil surrounding driven-pile foundations /." Diss., CLICK HERE for online access, 2008. http://contentdm.lib.byu.edu/ETD/image/etd2381.pdf.
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Adsero, Matthew E. "Impact of Jet Grouting on the Lateral Strength of Soil Surrounding Driven Pile Foundations." BYU ScholarsArchive, 2008. https://scholarsarchive.byu.edu/etd/1378.
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Jet grouting was used to strengthen the soft soil surrounding the piles and the pile cap of two full-scale driven pile foundations. Soilcrete columns, created by jet grouting, were placed underneath the pile cap and surrounding the piles of the first foundation. Two rows of soilcrete columns were placed around the perimeter of one-side of the second. All of the jet grouting took place after construction of the pile caps. Laboratory testing of the soilcrete slurry showed the columns as having a design unconfined compressive strength of 550-650 psi, compared with the native soil strength of only 6-8 psi (850-1150 psf). Lateral loading of the pile foundation was then performed on these foundations. The results of this test were compared with a similar test performed on the same foundations under native soil conditions. The total lateral capacity of the pile foundation treated underneath the pile cap was increased by 500 kips, which equals an increase of 175%. The total lateral capacity of the pile foundation treated adjacent to the pile cap was 150%. Results of testing suggest that each of the jet-grout treated zones displaced as a rigid block. A majority of the increased lateral resistance came from the passive soil resistance acting on the face of the blocks and the adhesive soil resistance acting on the sides and bottom of the block as it displaced through the native soil. The remaining soil resistance, not accounted for by the passive and adhesive soil resistance, can potentially be attributed to increased soil pile interaction, which is predicted from the decrease in pile head rotation during loading following soil treatment.
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Petek, Kathryn Ann. "Development and application of mixed beam-solid models for analysis of soil-pile interaction problems /." Thesis, Connect to this title online; UW restricted, 2006. http://hdl.handle.net/1773/10186.
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Korec, Michael. "Založení nové a sanované podpěry "Starého mostu" přes Dunaj v Bratislavě." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-227604.
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The thesis is focused on the reconnstruction of the "Old Bridge“ in Bratislava. Part of the reconstruction is the foundations of a new pier and redevelopment of an existing pier. The introduction provides an overview of methods used for the foundations within the river and from there onwards, the most suitable method haas been selected. The piers foundation is designed in several variants, coupled with the drawings. In conclusion, the variants were compared and the most suitable one was selected.
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Haskell, Jennifer Jane Margaret. "Guidance for the design of pile groups in laterally spreading soil." Thesis, University of Cambridge, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.648830.
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Tedesco, Giacomo. ""Offshore tower or platform foundations: numerical analysis of a laterally loaded single pile or pile group in soft clay and analysis of actions on a jacket structure"." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2014. http://amslaurea.unibo.it/6802/.
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Laterally loaded piles are a typical situation for a large number of cases in which deep foundations are used. Dissertation herein reported, is a focus upon the numerical simulation of laterally loaded piles. In the first chapter the best model settings are largely discussed, so a clear idea about the effects of interface adoption, model dimension, refinement cluster and mesh coarseness is reached. At a second stage, there are three distinct parametric analyses, in which the model response sensibility is studied for variation of interface reduction factor, Eps50 and tensile cut-off. In addition, the adoption of an advanced soil model is analysed (NGI-ADP). This was done in order to use the complex behaviour (different undrained shear strengths are involved) that governs the resisting process of clay under short time static loads. Once set a definitive model, a series of analyses has been carried out with the objective of defining the resistance-deflection (P-y) curves for Plaxis3D (2013) data. Major results of a large number of comparisons made with curves from API (America Petroleum Institute) recommendation are that the empirical curves have almost the same ultimate resistance but a bigger initial stiffness. In the second part of the thesis a simplified structural preliminary design of a jacket structure has been carried out to evaluate the environmental forces that act on it and on its piles foundation. Finally, pile lateral response is studied using the empirical curves.
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Angar, Mohammad Mustafa. "Reinforcement Layout in Concrete Pile Foundations : A study based on non - linear finite element analysis." Thesis, KTH, Betongbyggnad, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-278214.
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The main topic of this thesis concerns the behavior of concrete pile cap supported by four piles with two varying positions of longitudinal reinforcements. The positions include top of piles and bottom of the pile cap. For this purpose, non-linear finite element models of a pile cap are created using software ATENA 3D. The goal was to observe which position of reinforcement yields the higher bearing capacity and to observe the failure modes in the models. To achieve the above goals, a short review of theoretical background concerning shear phenomena is performed. This, in order to enhance the knowledge regarding shear stresses, shear transfer mechanism, factors affecting shear capacity, modes of shear failure and relate them to the behavior of pile cap. Furthermore, the calculation of shear resistance capacity based on Eurocode 2 using strut and tie method and sectional approach is presented. The numerical analysis started by creating four pile cap models in ATENA 3D. The difference between the models being the position and ratio of longitudinal reinforcement. The purpose behind two reinforcement ratios were to observe the behavior of pile cap model in two cases: a) when failure occurs prior to yielding of reinforcement; b) when failure occurs while reinforcement is yielding. The models are then analyzed using software ATENA Studio. The results revealed that placing the reinforcement on top of piles in case (a) increased the capacity of the model by 23.5 % and in case (b) increased the capacity by 18.5 %. This because the tensile stresses were found to be concentrated on top of piles rather than the bottom of the pile cap. The final failure mode in the model with top reinforcement position was crushing of the inclined compressive strut at the node beneath the column and in the model with bottom reinforcement position, the splitting of the compressive strut due to tensile stresses developed perpendicular to the inclined strut. The potential advantage of placing the reinforcement at the bottom were a better crack control in serviceability limit state and a slightly less fragile failure mode compared to the top position of reinforcement. A parametric study was performed in the model as well to observe the effects of various parameters on the results obtained. It was found that fracture energy had the most significant effect on the results obtained. Finally, a comparison between the results of numerical analysis and analytical design approaches based on strut and tie method and sectional approach was performed. The comparison reveals that the design values obtained based on strut and tie method for the model were very conservative. In particular, the equation for the strength of inclined compressive strut based on Eurocode 2 was very general.Det huvudsakliga ämnet för den här avhandlingen handlar om beteendet hos pålfundament som stöds av fyra pålar med två olika positioner av längsgående armering. Positionerna inkluderar toppen av pålarna och botten av slagdynan. För detta ändamål skapas icke-linjära finita elementmodeller av en slagdyna med mjukvaran ATENA 3D. Målet var att observera vilket armeringsläge som ger den högre bärkapaciteten och att identifiera brottmekanismen i modellerna. För att uppnå ovanstående mål utförs en kort genomgång av teoretisk bakgrund rörande skjuvningsfenomen. Detta för att förbättra kunskapen om skjuvspänningar, skjuvöverföringsmekanism, faktorer som påverkar skjuvkapacitet, skjuvbrott och relaterar dem till beteendet hos slagdynan. Beräkningen av skjuvmotståndet baserad på Eurocode2 med hjälp av Srut and tie-metod och sektionsmetod. Den numeriska analysen började med att skapa fyra pålfundament i ATENA 3D. Skillnaden mellan modellerna är positionen och förhållandet mellan längsgående armering. Syftet bakom två armeringsförhållanden var att observera beteendet hos slagdynan i två fall: a) när brott inträffar innan armering plasticeras; b) när brott inträffar medan armeringen plasticeras. Modellerna analyseras sedan med hjälp av programvaran ATENA Studio. Resultaten visade att placering av armeringen ovanpå pålarna i fall a) ökade modellens kapacitet med 23,5% och i fall (b) ökade kapaciteten med 18,5%. Detta på grund av att dragspänningarna visade sig vara koncentrerade på toppen av pålarna snarare än på botten av slagdynan. Det slutliga brottet i modellen med topparmeringsposition var krossning av det lutande tryckstaget vid noden under pelaren. I modellen med bottenarmeringsposition delades kompressionsstaget på grund av dragspänningar vinkelrätt mot det lutande staget. The potential advantage of placing the reinforcement at the bottom were a better crack control and slightly less fragile failure mode compared to the top position of reinforcement. En parametrisk studie genomfördes också i modellen för att observera effekterna av olika parametrar på de erhållna resultaten. Det visade sig att brottenergi hade den mest signifikanta effekten på de erhållna resultaten. Slutligen genomfördes en jämförelse mellan resultaten från numerisk analys och analytiska designmetoder baserade på strut and tie-metoden och sektionsmetoden. Jämförelsen avslöjar att de designvärden som erhölls baserat på strut and tie-metoden för modellen var mycket konservativa. I synnerhet var ekvationen för kapaciteten hos det lutande tryckstag baserad på Eurocode 2 mycket generell.
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Lemme, Nathan A. "Effectiveness of Compacted Fill and Rammed Aggregate Piers for Increasing Lateral Resistance of Pile Foundations." BYU ScholarsArchive, 2010. https://scholarsarchive.byu.edu/etd/2393.
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Compacted fill and rammed aggregate piers (RAPs) were separately installed adjacent to a 9-ft by 9-ft by 2.5-ft driven pile foundation founded in soft clay. The compacted fill used to laterally reinforce an area of 11 ft by 5 ft by 6 ft deep adjacent to the pile cap was clean concrete sand. The thirty-inch diameter RAPs were installed in three staggered rows to a depth of 12.5 ft below the ground surface adjacent to the pile cap to test the increase in lateral resistance afforded by their installation. The foundation was laterally loaded and load, displacement, and strain readings were recorded. The results of this testing were compared with similar tests performed with virgin soil conditions. The total lateral capacity of the pile foundation increased by 5 percent or14 kips due to compacted fill placement against the face of the pile cap. The passive force acting only on the pile cap decreased from 54 kips in the virgin case to 30 kips after installation of the compacted fill, a decrease of about 45 percent. The total lateral capacity of the pile foundation that was retrofit with RAPs was increased by 18 percent or 52 kips as compared to an identical pile cap in virgin clay. The passive force acting on the pile cap at 1.5 inches of pile cap displacement was determined to be approximately 50 kips, showing a slight decrease in passive resistance as compared to the tests performed on virgin soil. Both reinforcement techniques reduced pile head rotation and the bending moments in the shallow portions of the piles.
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Nasr, Jonathan A. "Development of a Design Guideline for Bridge Pile Foundations Subjected to Liquefaction Induced Lateral Spreading." PDXScholar, 2018. https://pdxscholar.library.pdx.edu/open_access_etds/4160.
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Effective-stress nonlinear dynamic analyses (NDA) were performed for piles in liquefiable sloped ground to assess how inertia and liquefaction-induced lateral spreading combine in long-duration vs. short-duration earthquakes. A parametric study was performed using input motions from subduction and crustal earthquakes covering a wide range of earthquake durations. The NDA results were used to evaluate the accuracy of the equivalent static analysis (ESA) recommended by Caltrans/ODOT for estimating pile demands. Finally, the NDA results were used to develop new ESA methods to combine inertial and lateral spreading loads for estimating elastic and inelastic pile demands.
The NDA results showed that pile demands increase in liquefied conditions compared to nonliquefied conditions due to the interaction of inertia (from superstructure) and kinematics (from liquefaction-induced lateral spreading). Comparing pile demands estimated from ESA recommended by Caltrans/ODOT with those computed from NDA showed that the guidelines by Caltrans/ODOT (100% kinematic combined with 50% inertia) slightly underestimates demands for subduction earthquakes with long durations. A revised ESA method was developed to extend the application of the Caltrans/ODOT method to subduction earthquakes. The inertia multiplier was back-calculated from the NDA results and new multipliers were proposed: 100% Kinematic + 60% Inertia for crustal earthquakes and 100% Kinematic + 75% Inertia for subduction earthquakes. The proposed ESA compared reasonably well against the NDA results for elastic piles. The revised method also made it possible to estimate demands in piles that performed well in the dynamic analyses but could not be analyzed using Caltrans/ODOT method (i.e. inelastic piles that remained below Fult on the liq pushover curve). However, it was observed that the pile demands became unpredictable for cases where the pile head displacement exceeded the displacement corresponding to the ultimate pushover force in liquefied conditions. Nonlinear dynamic analysis is required for these cases to adequately estimate pile demands.
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Choi, Sin Yi. "Improving termination criteria for press-in pile construction focusing on setup effects and cyclic loading effects /." View abstract or full-text, 2008. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202008%20CHOI.
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Winkley, Anna Margaret Mathieson. "Impacts of liquefaction and lateral spreading on bridge pile foundations from the February 22nd 2011 Christchurch earthquake." Thesis, University of Canterbury. Civil and Natural Resources Engineering, 2013. http://hdl.handle.net/10092/8705.
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The Mw 6.2 February 22nd 2011 Christchurch earthquake (and others in the 2010-2011 Canterbury sequence) provided a unique opportunity to study the devastating effects of earthquakes first-hand and learn from them for future engineering applications. All major events in the Canterbury earthquake sequence caused widespread liquefaction throughout Christchurch’s eastern suburbs, particularly extensive and severe during the February 22nd event. Along large stretches of the Avon River banks (and to a lesser extent along the Heathcote) significant lateral spreading occurred, affecting bridges and the infrastructure they support.
The first stage of this research involved conducting detailed field reconnaissance to document liquefaction and lateral spreading-induced damage to several case study bridges along the Avon River. The case study bridges cover a range of ages and construction types but all are reinforced concrete structures which have relatively short, stiff decks. These factors combined led to a characteristic deformation mechanism involving deck-pinning and abutment back-rotation with consequent damage to the abutment piles and slumping of the approaches.
The second stage of the research involved using pseudo-static analysis, a simplified seismic modelling tool, to analyse two of the bridges. An advantage of pseudo-static analysis over more complicated modelling methods is that it uses conventional geotechnical data in its inputs, such as SPT blowcount and CPT cone resistance and local friction. Pseudo-static analysis can also be applied without excessive computational power or specialised knowledge, yet it has been shown to capture the basic mechanisms of pile behaviour. Single pile and whole bridge models were constructed for each bridge, and both cyclic and lateral spreading phases of loading were investigated. Parametric studies were carried out which varied the values of key parameters to identify their influence on pile response, and computed displacements and damages were compared with observations made in the field. It was shown that pseudo-static analysis was able to capture the characteristic damage mechanisms observed in the field, however the treatment of key parameters affecting pile response is of primary importance. Recommendations were made concerning the treatment of these governing parameters controlling pile response. In this way the future application of pseudo-static analysis as a tool for analysing and designing bridge pile foundations in liquefying and laterally spreading soils is enhanced.
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Daoulas, John Christos. "Finite element analyses of pile load tests performed in the Yorktown formation, Newport News, Virginia." Thesis, Virginia Tech, 1988. http://hdl.handle.net/10919/43588.
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Ozturk, Sevki. "Distribution Of Bending Moments In Laterally Loaded Passive Pile Groups A Model Study." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/2/12610378/index.pdf.
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In this study, bending moment distributions developed in laterally loaded passive pile and passive pile groups in cohesionless soil were investigated in laboratory conditions through model pile experiments. Different from the active pile loading, the lateral load was given directly to the piles using a movable large direct shear box. In these experiments strain gauges fastened to the piles and a computer based data reading system were used. The strain values were measured at five levels on the piles. The behavior of a single pile and a pile group having five piles were investigated through strain measurements in order to observe bending moment distribution on the piles.
After evaluating the test results, the behavior of passive single pile was found to be similar to the results obtained in early studies. Negative bending moments were observed at the specified depths above the shear plane and positive bending moments were measured at the level of the shear plane and below the shear plane. Maximum bending moments were obtained at 0.7L (L: Length of Pile) for single piles and piles in the group. Above the shear plane, maximum bending moments within the pile
group were found to be developed on the piles nearest to the loading. On the shear plane maximum bending moments were developed on the piles farthest from the loading just like active piles. Below the shear plane, maximum bending moments were developed mainly on the piles nearest to the loading.