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1
Chen, Yung-Chieh. "Seismic bearing capacity of shallow and deep strip foundation." Thesis, Imperial College London, 1997. http://hdl.handle.net/10044/1/8665.
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Vimalaraj, Panchalingam. "A simple equation for bearing capacity of a shallow foundation." abstract and full text PDF (free order & download UNR users only), 2006. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1438933.
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Kenny, M. J. "The bearing capacity of clay overlain by unreinforced and reinforced sand." Thesis, University of Strathclyde, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382354.
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Tiwari, Dipak. "BEARING CAPACITY OF SHALLOW FOUNDATION USING GEOGRID REINFORCED DOUBLE LAYERED SOIL." OpenSIUC, 2011. https://opensiuc.lib.siu.edu/theses/772.
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Since the last three decades, several studies have been conducted related to improvement in bearing capacity of pavements, embankments, and shallow foundations resting on geosynthetic reinforced soil. Most of the work has been carried out on single layer soil e.g., sand or clay layer only. Very few studies are available on a double layer soil system; but no study is available on the local soil of Carbondale, Illinois. The present study investigates the physical and engineering properties of a local soil and commonly available sand and improvement in the bearing capacity of a local soil for a rectangular footing by replacing top of the local soil with sand layer and placing geogrids at different depths. Seven tests on the model footing were performed to establish the load versus settlement curves of unreinforced and reinforced soil supporting a rectangular foundation. The improvement in bearing capacity is compared with the bearing capacity of the local soil and double layer unreinforced soil system. The test results focus on the improvement in bearing capacity of local soil and double layer unreinforced soil system in non-dimensional form i.e., BCR (Bearing Capacity Ratio). The results obtained from the present study show that bearing capacity increases significantly with the increasing number of geogrid layers. The bearing capacity for double layer soil increases, by placing three inch sand layer at the top of local soil, was not significant. The bearing capacity of the local soil increased at an average of 7% with three inches sand layer. The bearing capacity for the double layer soil increases with an average of 16.67% using one geogrid layer at interface of soils (i.e., local soil and sand) with u/B equal to 0.67. The bearing capacity for the double layer soil increases with an average of 33.33% while using one geogrid in middle of sand layer having u/B equal to 0.33. The improvement in bearing capacity for double layer soil maintaining u/B equal to 0.33 and h/B equal to 0.33; for two, three and four number geogrid layer were 44.44%, 61.11%, 72.22%, respectively. The results obtained from this research work may be useful for the specific condition or similar type of soil available anywhere to improve the bearing capacity of soil for foundation and pavement design.
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Rica, Shilton [Verfasser]. "Improved Design Methods for the Bearing Capacity of Foundation Piles / Shilton Rica." Düren : Shaker, 2019. http://d-nb.info/120221875X/34.
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Evans, Keith Martin. "A model study of the end bearing capacity of piles in layered calcareous soils." Thesis, University of Oxford, 1987. http://ora.ox.ac.uk/objects/uuid:574ae32d-bb91-4be7-aae6-d456f4c40b70.
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The results of a series of over 120 model tests to study the end bearing capacity of piles in layered calcareous soils are described. The tests were carried out on samples enclosed in a cylindrical testing chamber, 450 mm diameter and 450 mm high, which allowed independent control of horizontal and vertical stress in the range 25 kPa to 500 kPa. The samples consisted of a loose, uncemented calcareous sand consisting predominantly of foraminifera and mollusc micro-organisms (D50 = 0.2 mm, calcium carbonate content 92%). Into this was built a layer of the same material artificially cemented by a gypsum plaster. The layer had similar properties to naturally cemented deposits, and layers with unconfirmed crushing strengths in the range 500 kPa to 4000 kPa have been prepared. All samples were tested dry. Closed end model piles of 16mm diameter were jacked at 0.1mm/s into the sample, and continuous profiles of end bearing capacity obtained during penetration. A parametric study has been carried out to examine the effects on the bearing capacity of stress level, K0, cemented layer thickness (0.5 pile diameters to 5.0 pile diameters) and layer strength. In addition, tests have been conducted with different pile geometry, multiple cemented layers, and using dynamic installation techniques. The study has identified ranges of parameters for which brittle failure of the cemented layer occurs (low stress levels and high layer strengths) and ranges where the failure is ductile (high stresses and low layer strengths). Characteristic patterns have been observed of the variation of end bearing with position as a layer is penetrated. Examination of the samples after testing has revealed details of failure mechanisms. Simple procedures are proposed for modelling the bearing capacity of such layered systems, and some implications of the results for design methods are discussed.
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Hossain, Muhammad Shazzad. "Investigation of Soil Failure Mechanisms during Spudcan Foundation Installation." Thesis, Curtin University, 2004. http://hdl.handle.net/20.500.11937/2614.
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Mobile jack-up rigs are widely used in offshore oil and gas exploration and increasingly in temporary production and maintenance work. There is a steadily increasing demand for their use in deeper water and harsher environments. A typical modem jack-up has three independent legs, each equipped with a footing known as ‘spudcan’. This thesis is concerned with the performance of spudcan foundation subjected to vertical loading correspondent to preloading during its installation into uniform clay. The chief aim of this study is to investigate the bearing behaviour with the corresponding soil failure mechanisms during spudcan penetration. Centrifuge model test and Finite Element (FE) analysis are carried out extensively. In centrifuge modelling, a half-spudcan model and a full spudcan model are used. In the half- spudcan model test, a novel system for revealing soil failure mechanisms and measuring soil deformation has been adopted, in which the half-spudcan model is placed against a transparent window and a subsequent Particle Image Velocimetry (PIV) analysis is performed. The full-spudcan model test is conducted to measure the load-penetration response. In numerical simulation, both small strain and large deformation analyses are carried out with smooth and rough soil-spudcan interfaces considered. At the initial stage of penetration, it is observed that a cavity is formed above the spudcan as it is penetrating into a uniform clay. Meanwhile, soil flows towards the surface and thus soil heave forms close to the spudcan shoulders. With further penetration, the soil underneath the spudcan starts to flow back into the cavity on the exposed top of the spudcan. This backflow causes the spudcan to be embedded while the initially formed cavity remains open.Eventually, the spudcan becomes fully embedded and the soil flow mechanism reaches a fully localised failure mechanism with deep embedment. The lateral extent of visible distortion due to soil flow is confined well within 1.5-1.6 D (D: spudcan diameter). From both centrifuge and numerical investigations, it is found that in uniform clay, it is inevitable to form a cavity above the spudcan foundation. Thus, the stable cavity depth and soil back flow mechanisms are studied. It is clear that the back flow is caused by a Flow Failure, where it is due to the downward penetration of the spudcan. This is contrary to the Wall Failure that is the mechanism recommended by the current offshore design guidelines to estimate the stable cavity depth. In wall failure, the soil back flow is due to the cavity wall too high to stand. The stable cavity depth is estimated up to 4 times higher by the wall failure mechanism than the one by the flow failure. This explains that the wall failure is never observed in model test. Therefore, a new design chart with design formula is developed for design engineers in the stable cavity depth calculation. The spudcan bearing response is strongly correspondent with the variation of soil failure mechanisms during penetration. At the initial stage of the penetration, the spudcan bearing capacity increases with penetration, which is due to the increase of overburden pressure from cavity formation. At the second stage of the penetration, soil back flow embeds the spudcan, and the spudcan bearing capacity is increasing as the soil flow mechanism transits from its shallow failure mechanism to its deep failure mechanism.At the final stage of the penetration, the spudcan bearing capacity reaches its ultimate value, where the deep/localised failure mechanism remains. A rough spudcan shows 14 % higher bearing capacity than a smooth spudcan. And a flat-plate shows 8 % higher capacity than a spudcan with a same surface roughness. The ultimate bearing capacity factor N, = 10.5 in uniform soil is recommended as a conservative value when the deep failure mechanism is reached. A correspondent N, = 10.1 in NC clay is suggested for a deeply embedded spudcan.
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Hossain, Muhammad Shazzad. "Investigation of Soil Failure Mechanisms during Spudcan Foundation Installation." Curtin University of Technology, Department of Civil Engineering, 2004. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=15369.
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Mobile jack-up rigs are widely used in offshore oil and gas exploration and increasingly in temporary production and maintenance work. There is a steadily increasing demand for their use in deeper water and harsher environments. A typical modem jack-up has three independent legs, each equipped with a footing known as ‘spudcan’. This thesis is concerned with the performance of spudcan foundation subjected to vertical loading correspondent to preloading during its installation into uniform clay. The chief aim of this study is to investigate the bearing behaviour with the corresponding soil failure mechanisms during spudcan penetration. Centrifuge model test and Finite Element (FE) analysis are carried out extensively. In centrifuge modelling, a half-spudcan model and a full spudcan model are used. In the half- spudcan model test, a novel system for revealing soil failure mechanisms and measuring soil deformation has been adopted, in which the half-spudcan model is placed against a transparent window and a subsequent Particle Image Velocimetry (PIV) analysis is performed. The full-spudcan model test is conducted to measure the load-penetration response. In numerical simulation, both small strain and large deformation analyses are carried out with smooth and rough soil-spudcan interfaces considered. At the initial stage of penetration, it is observed that a cavity is formed above the spudcan as it is penetrating into a uniform clay. Meanwhile, soil flows towards the surface and thus soil heave forms close to the spudcan shoulders. With further penetration, the soil underneath the spudcan starts to flow back into the cavity on the exposed top of the spudcan. This backflow causes the spudcan to be embedded while the initially formed cavity remains open.<br>Eventually, the spudcan becomes fully embedded and the soil flow mechanism reaches a fully localised failure mechanism with deep embedment. The lateral extent of visible distortion due to soil flow is confined well within 1.5-1.6 D (D: spudcan diameter). From both centrifuge and numerical investigations, it is found that in uniform clay, it is inevitable to form a cavity above the spudcan foundation. Thus, the stable cavity depth and soil back flow mechanisms are studied. It is clear that the back flow is caused by a Flow Failure, where it is due to the downward penetration of the spudcan. This is contrary to the Wall Failure that is the mechanism recommended by the current offshore design guidelines to estimate the stable cavity depth. In wall failure, the soil back flow is due to the cavity wall too high to stand. The stable cavity depth is estimated up to 4 times higher by the wall failure mechanism than the one by the flow failure. This explains that the wall failure is never observed in model test. Therefore, a new design chart with design formula is developed for design engineers in the stable cavity depth calculation. The spudcan bearing response is strongly correspondent with the variation of soil failure mechanisms during penetration. At the initial stage of the penetration, the spudcan bearing capacity increases with penetration, which is due to the increase of overburden pressure from cavity formation. At the second stage of the penetration, soil back flow embeds the spudcan, and the spudcan bearing capacity is increasing as the soil flow mechanism transits from its shallow failure mechanism to its deep failure mechanism.<br>At the final stage of the penetration, the spudcan bearing capacity reaches its ultimate value, where the deep/localised failure mechanism remains. A rough spudcan shows 14 % higher bearing capacity than a smooth spudcan. And a flat-plate shows 8 % higher capacity than a spudcan with a same surface roughness. The ultimate bearing capacity factor N, = 10.5 in uniform soil is recommended as a conservative value when the deep failure mechanism is reached. A correspondent N, = 10.1 in NC clay is suggested for a deeply embedded spudcan.
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Králík, Michal. "Návrh založení dálničního mostu." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2019. http://www.nusl.cz/ntk/nusl-392075.
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Topic of this master`s thesis is founding of the hightway bridge, which is located between Lipník and Bělotín. Thesis is aimed for creating shallow foundation and foundation on piles and choosing which option is better. All evaluations have been made without specialized software and than compared with GEO5 results. Better solution will be completed with procedure for construction and drawing documentation.
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CIANCIMINO, ANDREA. "Performance of caisson foundations subjected to flood-induced scour." Doctoral thesis, Politecnico di Torino, 2021. http://hdl.handle.net/11583/2924992.
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Li, Davelouis Julio Raúl, and Chávez Juan Segundo Zegarra. "Diseño de propuestas de solución y evaluación técnico-económica para la cimentación de tres edificios de concreto armado de sistema de muros de 4, 6 y 8 pisos situados en un suelo de capacidad portante de 1.01kg/cm2." Bachelor's thesis, Universidad Peruana de Ciencias Aplicadas (UPC), 2019. http://hdl.handle.net/10757/626088.
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Se retirará este documento a solicitud del Sandra Rodriguez Dionisio, Coordinador de carrera de Ingeniería Civil. Fecha de solicitud mediante correo electrónuico 19-09-2019<br>La investigación consiste en la evaluación técnico-económica de tres alternativas de cimentación, las cuales son platea de cimentación, sistema de zapatas y micropilotes, estudiadas en tres proyectos situados en un suelo de baja capacidad portante igual a 1.01kg/cm2. Esto con el objetivo de determinar la alternativa de solución más óptima en función a los criterios técnico y económico, teniendo en cuenta que la opción de platea de cimentación es comúnmente la más empleada. En cuanto a los proyectos, estos corresponden a edificios multifamiliares de 4, 6 y 8 pisos, de material de concreto armado, de sistema estructural a base de muros y sin sótanos. Estos ese encuentran situados en un suelo arenoso (SP-SM), sin presencia del nivel freático ni fallas geológicas, perteneciente al distrito de Ica, provincia de Ica, departamento de Ica, Perú. Respecto al diseño de las alternativas de cimentación, estas se rigen bajo las exigencias de las normas de diseño vigentes en el Perú, correspondientes al Reglamento Nacional de Edificaciones (RNE). Asimismo, se utilizaron programas de software como ETABS y SAP2000, para complementar el análisis estructural de los edificios y diseño de las alternativas de cimentación. Posterior al diseño, se realizó la evaluación técnico-económica, proponiendo un plan de ejecución (cronograma) acorde con las características y contexto del proyecto, como también un presupuesto económico para cada caso. Finalmente, mediante un análisis comparativo que contrasta ambos criterios, se concluye la alternativa de cimentación más óptima para cada caso de estudio.<br>The investigation consists in technical and economic evaluation of foundation alternatives, which are foundation plate, shoe system and micropiles, for three projects located in a low bearing capacity soil of to 1.01kg/cm2. The study objective is determine the best foundation alternative according to technical and economic criteria, taking into account that foundation plate is commonly the most used. Corresponding to the projects, these are multifamily buildings of 4, 6 and 8 floors, of reinforced concrete material, structural system based on walls and without basements. In the same way, these projects are located in a sandy soil (SP-SM), without freatic level presence neither geological fails, located in Ica district, Ica province, Ica department, Peru. On the other hand, according to the foundation alternatives design, these are supported by the requirements of the peruvian design rules “Reglamento Nacional de Edificicaciones” (RNE). In the same way, software programs such as ETABS and SAP2000 were used to complement the study of buildings structural performance and foundation alternatives. After design, the technical-economic evaluation was carried out, proposing an execution plan (schedule) according to the characteristics and context of the projects, and an economic budget for each case. Finally, through a comparative analysis that contrats both criteria, the best foundation alternative por each case is concluded.<br>Tesis
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Peri, Elena. "An investigation on the behaviour of a shallow foundation resting on a layered soil near a slope." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2016.
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In questo progetto, portato avanti alla University of Western Australia, viene analizzato il comportamento di una fondazione superficiale su un pendio in sabbia sopra un deposito di argilla.
Dopo avere ricavato sperimentalmente i parametri di resistenza di sabbia e argilla, si è proceduto al calcolo con Plaxis 2D della capacità portante della fondazione a striscia sopra questa stratigrafia. I parametri che sono stati considerati in questi modelli sono sia geometrici che di resistenza.
Dopo l'analisi numerica si è elaborata un'equazione che lega capacità portante e tutti i parametri.
Oltre alla parte 2D si è studiata un'applicazione pratica 3D. Con Plaxis 3D si sono calcolati modelli rappresentanti un bulldozer su un pendio in sabbia sopra un deposito di terreno a grana fine.
Anche per questa applicazione si è elaborata un'equazione per ricavare la capacità portante.
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Conti, Claudio. "Small-scale physical modelling of piled foundations for offshore wind turbines application." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019.
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Nowadays, finding alternative energy sources is becoming more and more important. Europe is particularly focusing on wind energy and in offshore wind energy especially. An issue concerning offshore wind energy which is gaining more and more attention is the noise emissions due to impact driven pile foundation. The noise caused by the installation process has been judged as “potentially dangerous for marine fauna” from the German Authorities.
This research thesis is part of a project which examines a viable alternative installation method for the displacement of pile foundations for offshore wind energy called pile jacking. This technology should be developed to be cost-efficient, flexibly scalable and to produce considerably reduced vibration and air pollution emissions during its placement in the sea bed. Jacked piles technology would eliminate almost any noise deriving from the hammer impact.
As most offshore piled foundations have been installed by impact driving technology, the question arises as to how piles with different the stiffness and the capacity , can otherwise be installed.
In order to delineate the significant variables affecting the load-bearing capacity and especially the ultimate uplift capacity of a pile in saturated sand, a small-scale test campaign in scale 1:30 has been performed at the Test Center for Support Structures in Hanover. The campaign was supervised by the Department for Support Structures of Fraunhofer IWES. A testing schedule comprising of 15 small-scale geotechnical physical experiments was conducted on open-ended piles to an embedded length of 75 cm using two method of pile installation: static jacking and impact driving.
The aim of this thesis is to obtain preliminary experimental data and set out the main features of this technology.
The results obtained by this study reveal that static jacking installation lead to higher resistances and is overall beneficial to the mechanical load bearing behavior of pile foundations.
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López, Ana Priscilla Paniagua. "Two- and three-dimentional bearing capacity of shallow foundations." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for bygg, anlegg og transport, 2010. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-14406.
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Tapper, Laith. "Bearing capacity of perforated offshore foundations under combined loading." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:4beb1f5c-24d9-4359-a973-95dda05e550d.
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This thesis presents experimental work and numerical analysis that has been undertaken to assess the bearing capacity of perforated offshore foundations. Perforated foundations may be used to support subsea infrastructure, including as mudmats into which a number of perforations have been made, or as grillages which consist of a series of structurally connected strip footings. Larger gravity base foundations, such as for offshore wind turbines or oil and gas platforms, may adopt a single central perforation. The advantages of using perforated foundations can include reduced material requirements and easier offshore handling as a result of smaller weight and lower hydrodynamic forces during deployment. Limited guidance currently exists for assessing the bearing capacity of these foundation types. Bearing capacity of perforated foundations has been examined in this thesis under conditions of combined vertical, horizontal and moment loading which is typical in offshore settings. Undrained soil conditions have been considered, except for the case of grillages in which drained conditions are often most relevant. Experimental work has included centrifuge testing of ring and square annular foundations on clay, and 1g testing of grillage foundations on sand. Finite element modelling has also been undertaken to assess perforated foundation capacity. A Tresca material subroutine (UMAT) and an adaptive meshing scheme have been developed to improve the accuracy of the finite element analysis carried out. The results showed that perforated foundations can be an efficient foundation solution for accommodating combined loading. As a ratio of their vertical load capacity, perforated foundations may be able to withstand higher moment and horizontal loads compared with unperforated foundations. The experimental and numerical results have been used to develop design expressions that could be employed by practitioners to estimate the vertical and combined load bearing capacity of these foundation types.
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Amann, Kurt André Pereira. "Metodologia semiempírica unificada para a estimativa da capacidade de carga de estacas." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/3/3145/tde-21102010-094919/.
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A pesquisa parte do fato de que os métodos semiempíricos de estimativa da capacidade de carga de estacas não devem ser empregados indiscriminadamente em qualquer região do país sem as devidas adequações às características do solo local. Constata-se, com isso, que não existem metodologias específicas para proceder tais adequações e que o meio técnico acaba por realizar a mera classificação dos métodos em conservador ou contra a segurança, o que se constitui num certo paradigma. Assim, o presente trabalho propõe uma Metodologia Semiempírica Unificada (MSU), em três etapas. Na primeira delas, o projetista estima a capacidade de carga a partir da otimização das melhores práticas adotadas pelos diversos métodos semiempíricos utilizados no Brasil. Discutem-se ainda o embutimento da ponta e a criação de novos métodos semiempíricos. Na segunda etapa, realiza-se a verificação de desempenho com base nos critérios de ruptura aplicados à curva carga-recalque de provas de carga. Nessa etapa, as imprecisões do dito paradigma são apontadas e faz-se uma nova proposta de aplicação dos critérios de ruptura. Na terceira etapa, faz-se uma retroanálise para aferição da estimativa semiempírica unificada da primeira etapa. Propõe-se, assim, o uso da separação das parcelas de atrito e ponta por meio de métodos de transferência de carga, bem como pela proposta de ajustes polinomiais, no caso de ensaios instrumentados. A análise crítica desse processo gerou a proposta de uma nova abordagem matemática da transferência de carga. A correção dos valores adotados para os coeficientes semiempíricos de cada camada, individualmente, é feita pela proposta de aplicação do conceito de Hierarquia dos Solos (AMANN, 2000). Os resultados de correção dos métodos semiempíricos, contudo, são específicos para o solo de cada local em estudo. Assim, são utilizados, como exemplo, ensaios em diversas regiões do país, o que permite a verificação da aplicabilidade da metodologia proposta.<br>The research starts from the fact that the semiempirical methods for estimating the pile load capacity shouldn\'t be used indiscriminately in any country\'s region without making proper adjustments to the local soil characteristics. It is verified, from this, that there are no specific methodologies to make such adjustments and the geotechnical engineers find themselves forced to perform a simple classification of the methods in \"conservative\" or \"against the safety\", which constitutes a form of paradigm. In this context, this paper proposes a Unified Semiempirical Methodology (MSU) in three steps. In the first, the designer estimates the foundation load capacity from the optimization of best practices adopted by different semiempirical methods used in Brazil. A discussion is also made the toe embedment and the creation of new semiempirical methods. In the second step, the verification of the foundation performance is carried out, based on the failure criteria applied to the load-settlement curve of load tests. At this step, the inaccuracies from that paradigm are outlined and a new proposal is made for applying the failure criteria. In the third step, a backanalysis is accomplished to admeasure the unified semiempirical estimative from the first step. It is, thus, proposed to separate both shaft friction and toe resistance from the total load, by means of load transfer methods, and by the proposal of polynomial adjustments in the case of instrumented piles. With the critical analysis of this process, a new mathematical approach to load transfer is presented. The correction of the coefficients of the semiempirical methods is made by the application of the Soils\'s Hierarchy concept (AMANN, 2000). The results of semiempirical methods correction, however, are specific to the soils of each particular site. The applicability, of the proposed methodology, is illustrated using pile load tests from various parts of the country.
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Quoc, Van Nguyen. "Numerical modelling of the undrained vertical bearing capacity of shallow foundations." University of Southern Queensland, Faculty of Engineering and Surveying, 2008. http://eprints.usq.edu.au/archive/00006257/.
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[Abstract]The bearing capacity of foundations is a fundamental problem in geotechnical engineering. For all structures placed on a soil foundation, geotechnical engineers must ensure that the soil has sufficient load carrying capacity so that the foundation does not collapse or become unstable under any conceivable loading. The ultimate bearing capacity is the magnitude of bearing pressure at which the supporting ground is expected to fail in shear, i.e. a collapse will take place.During the last fifty years various researchers have proposed approximate techniques to estimate the short term undrained bearing capacity of foundations. The majority of existing theories are not entirely rigorous and contain many underlying assumptions. As a consequence, current design practices include a great deal of empiricism. Throughout recent decades, there has also been a dramatic expansion in numerical techniques and analyses, however, very few rigorous numerical analyses have been performed todetermine the ultimate bearing capacity of undrained soils.In this study, finite element analysis has been used to analyse a range of bearing capacity problems in undrained soil. The numerical models account for a range of variablesincluding footing size, shape, embedment depth, soil layering and undrained bearing capacity of footings on slopes.By using the powerful ability of computers a comprehensive set of solutions have been obtained therefore reducing the uncertainties apparent in previous solutions.
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Taiebat, Hossein Ali. "THREE DIMENSIONAL LIQUEFACTION ANALYSIS OF OFFSHORE FOUNDATIONS." Thesis, The University of Sydney, 1999. http://hdl.handle.net/2123/499.
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This thesis presents numerical techniques which have been developed to analyse three dimensional problems in offshore engineering. In particular, the three dimensional liquefaction analysis of offshore foundations on granular soils is the main subject of the thesis. The subject matter is broadly divided into four sections: 1)Development of an efficient method for the three dimensional elasto?plastic finite element analysis of consolidating soil through the use of a discrete Fourier representation of field quantities. 2)Validation of the three dimensional method through analyses of shallow offshore foundations subjected to three dimensional loading and investigation of the yield locus for foundations on purely cohesive soils. 3)Formulation of governing equations suitable for three dimensional liquefaction analyses of offshore foundations founded on granular soil, presentation of a method for liquefaction analyses, and application of the method in modified elastic liquefaction analyses of offshore foundations. 4)Application of a conventional elasto?plastic soil model in the liquefaction analyses of offshore foundations using the three dimensional finite element method. The finite element method developed in this thesis provides a rigorous and efficient numerical tool for the analysis of geotechnical problems subjected to three dimensional loading. The efficiency of the numerical tool makes it possible to tackle some of the problems in geotechnical engineering which would otherwise need enormous computing time and thus would be impractical. The accuracy of the numerical scheme is demonstrated by solving the bearing capacity problem of shallow foundations subjected to three dimensional loading. The generalized governing equations and the numerical method for liquefaction analyses presented in this thesis provide a solid base for the analysis of offshore foundations subjected to cyclic wave loading where they are founded on potentially liquefiable soil. The practicability of the numerical scheme is also demonstrated by a modified elastic liquefaction analysis of offshore foundations. The liquefaction phenomenon is redefined in the context of the conventional Mohr?Coulomb model, so that a relatively simple and practical model for elasto?plastic liquefaction analysis is presented. The three dimensional finite element method together with the numerical scheme for liquefaction analysis and the elasto?plastic soil model provide a suitable practical engineering tool for exploring the responses of offshore foundations subjected to cyclic wave loading.
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Taiebat, Hossein Ali. "THREE DIMENSIONAL LIQUEFACTION ANALYSIS OF OFFSHORE FOUNDATIONS." University of Sydney. Civil Engineering, 1999. http://hdl.handle.net/2123/499.
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This thesis presents numerical techniques which have been developed to analyse three dimensional problems in offshore engineering. In particular, the three dimensional liquefaction analysis of offshore foundations on granular soils is the main subject of the thesis. The subject matter is broadly divided into four sections: 1)Development of an efficient method for the three dimensional elasto?plastic finite element analysis of consolidating soil through the use of a discrete Fourier representation of field quantities. 2)Validation of the three dimensional method through analyses of shallow offshore foundations subjected to three dimensional loading and investigation of the yield locus for foundations on purely cohesive soils. 3)Formulation of governing equations suitable for three dimensional liquefaction analyses of offshore foundations founded on granular soil, presentation of a method for liquefaction analyses, and application of the method in modified elastic liquefaction analyses of offshore foundations. 4)Application of a conventional elasto?plastic soil model in the liquefaction analyses of offshore foundations using the three dimensional finite element method. The finite element method developed in this thesis provides a rigorous and efficient numerical tool for the analysis of geotechnical problems subjected to three dimensional loading. The efficiency of the numerical tool makes it possible to tackle some of the problems in geotechnical engineering which would otherwise need enormous computing time and thus would be impractical. The accuracy of the numerical scheme is demonstrated by solving the bearing capacity problem of shallow foundations subjected to three dimensional loading. The generalized governing equations and the numerical method for liquefaction analyses presented in this thesis provide a solid base for the analysis of offshore foundations subjected to cyclic wave loading where they are founded on potentially liquefiable soil. The practicability of the numerical scheme is also demonstrated by a modified elastic liquefaction analysis of offshore foundations. The liquefaction phenomenon is redefined in the context of the conventional Mohr?Coulomb model, so that a relatively simple and practical model for elasto?plastic liquefaction analysis is presented. The three dimensional finite element method together with the numerical scheme for liquefaction analysis and the elasto?plastic soil model provide a suitable practical engineering tool for exploring the responses of offshore foundations subjected to cyclic wave loading.
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Meng, Qiuhong. "Bearing capacity failure envelopes of foundations with skirts subjected to combined loading." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for bygg, anlegg og transport, 2013. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-23367.
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The bearing capacity of the foundation is reduced in combination with horizontal loads and moments, and can be further reduced when torsion moment is applied. Therefore, torsion moment must be taken into account when calculating the loading capacity. This is particularly relevant for offshore foundations (underwater structures), since torsion is often of considerable size.The aim of this thesis is to make a numerical study of a rectangular mudmat foundation subjected to vertical loading, horizontal loading and torsion moment. The numerical calculations were mainly calculated by the finite element program PLAXIS 3D. Meanwhile, hand calculations of bearing capacities with Janbu and Davis & Booker methods are also carried out for comparison. The numerical studies were limited to undrained loading condition, where the undrained shear strength increases linearly with depth for a rectangular mudmat foundation; a) with outer skirts only b) with both outer and inner skirtsVertical and horizontal bearing capacities of mudmat foundation from finite element program PLAXIS 3D correspond well with the hand calculation results by Janbu method. However, the vertical bearing capacities from PLAXIS 3D are slightly higher than Janbu method, with a differencial value of 460kN(Model 1) and 80 kN(Model 2), corresponding to a differencial of 6% and 1%, respectively. It may have several explanations:?The results of finite element programs is dependent on network element and element type. Theoretically, the analyses of model with more fine meshes and smaller average element size would generate more accurate results. ?PLAXIS 3D bulids a real 3-dimensional model, taking into consideration the 3D effections. However, Janbu method is based on the plane strain. However, torsional bearing capacity from PLAXIS 3D is almost twice the value determined from hand calculations, which may because of the conservative calculation method or some possible parametrical errors in PLAXIS 3D. By intergrating the FEM analyses package PLAXIS 3D with the Swipe test procedure of loading, the failure envelopes of mudmat foundation and approximating expressions are investigated. Through numerical computations and comparative analyses based on FEM, the two-dimensional failure envelopes of mudmat foundation are established by using proposed method to evaluate the stability of foundation under combined loadings. These results could be utilized to provide vital reference for the design and construction of mudmat foundation.
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Zhu, Fanyu. "Centrifuge modelling and numerical analysis of bearing capacity of ring foundations on sand." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0003/NQ36219.pdf.
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Al-Aghbari, Mohammed Yousuf Saif. "Bearing capacity of shallow strip foundations with structural skirts resting on dense sand." Thesis, University of Strathclyde, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367023.
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Makusa, Gregory Paul. "Mechanical properties of stabilized dredged sediments : for sustainable geotechnical structures." Licentiate thesis, Luleå tekniska universitet, Geoteknologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-17437.
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Dredging activities at Ports and Harbors are inevitable for the safe navigation of ships and vessels. Dredged material may range from very fine and contaminated sediments to sand and gravels. While, granular dredged material can be directly utilized in civil engineering applications, fine sediments may require further treatment before use. In geotechnical context, fine sediments are characterized by low shear strength and high compressibility. However, these unfavorable properties do not rule out the suitability of these fine dredged sediments for use in geotechnical construction, such as, road embankment, building foundation or as structural backfill in land reclamation. Mass stabilization solidification provides a comprehensive technology for amending fine sediments at high initial water content, resulting into construction materials of improved strength and reduced compressibility. The ultimate in-situ soil behavior types, stiffness and strength properties of stabilized mass depend on various factors such as binders, mixing equipment, curing temperature, in-situ boundary conditions and mostly important the applied preloading weight during the period of curing. However, despite improved mechanical properties for geotechnical applications, the performance of treated materials becomes susceptible to repeated freeze-thaw cycles. Understanding geotechnical design process, which includes evaluation of material properties, loading condition and selection of appropriate constitutive model, is an important task for settlement and stability analysis of structures founded on stabilized mass. The selection of suitable material model is vital for successful finite element analysis. Nevertheless, among all existing constitutive soil models, none of them can capture all aspects of soil behavior. Therefore, the meaningful and quantifiable predictions of field behaviors are possible only if, undisturbed samples or in-situ tests are used for determination of mechanical properties, and the predictive capacity of selected constitutive model comes from the comparison with field observations In the present research work, utilization of cone penetration test (CPT) data for evaluating the mechanical properties of stabilized dredged sediments for geotechnical design and analysis was presented. A large-scale field test at the Port of Gävle was utilized as a case study, to verify the simulated settlement of preloaded stabilized dredged sediments. The stabilized mass–soil classification behavior type was studied utilizing CPT classification charts. Computation of the primary consolidation settlement due to preloading weight were carried out in PLAXIS 2D geotechnical software and verified against field measurements. A suggestion to protect the stabilized mass against severe weather condition was discussed.<br>Godkänd; 2013; 20130409 (makusa); Tillkännagivande licentiatseminarium 2013-04-25 Nedanstående person kommer att hålla licentiatseminarium för avläggande av teknologie licentiatexamen. Namn: Gregory Paul Makusa Ämne: Geoteknik/Soil Mechanics and Foundation Engineering Uppsats: Mechanical Properties of Stabilized Dredged Sediments for Sustainable Geotechnical Structures Examinator: Professor Sven Knutsson, Institutionen för samhällsbyggnad och naturresurser, Luleå tekniska universitet Diskutant: Civ.ing. Forskningsdirektör Göran Holm, Statens Geotekniska Institut, Linköping Tid: Torsdag den 16 maj 2013 kl 10.00 Plats: F1031, Luleå tekniska universitet
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Mohamed, Fathi Mohamed Omar. "Bearing Capacity and Settlement Behaviour of Footings Subjected to Static and Seismic Loading Conditions in Unsaturated Sandy Soils." Thèse, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/30661.
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Several studies were undertaken by various investigators during the last five decades to better understand the engineering behaviour of unsaturated soils. These studies are justified as more than 33% of soils worldwide are found in either arid or semi-arid regions with evaporation losses exceeding water infiltration. Due to this reason, the natural ground water table in these regions is typically at a greater depth and the soil above it is in a state of unsaturated conditions. Foundations of structures such as the housing subdivisions, multi-storey buildings, bridges, retaining walls, silos, and other infrastructure constructed in these regions in sandy soils are usually built within the unsaturated zone (i.e., vadose zone). Limited studies are reported in the literature to understand the influence of capillary stresses (i.e., matric suction) on the bearing capacity, settlement and liquefaction potential of unsaturated sands. The influence of matric suction in the unsaturated zone of the sandy soils is ignored while estimating or evaluating bearing capacity, settlement and liquefaction resistance in conventional engineering practice. The focus of the research presented in the thesis has been directed towards better understanding of these aspects and providing rational and yet simple tools for the design of shallow foundations (i.e., footings) in sands under both static and dynamic loading conditions.
Terzaghi (1943) or Meyerhof (1951) equations for bearing capacity and Schmertmann et al. (1978) equation for settlement are routinely used by practicing engineers for sandy soils based on saturated soil properties. The assumption of saturated conditions leads to conservative estimates for bearing capacity; however, neglecting the influence of capillary stresses contributes to unreliable estimates of settlement or differential settlement of footings in unsaturated sands. There are no studies reported in the literature on how capillary stresses influence liquefaction, bearing capacity and settlement behavior in earthquake prone regions under dynamic loading conditions. An extensive experimental program has been undertaken to study these parameters using several specially designed and constructed equipment at the University of Ottawa.
The influence of matric suction, confinement and dilation on the bearing capacity of model footings in unsaturated sand was determined using the University of Ottawa Bearing Capacity Equipment (UOBCE-2011). Several series of plate load tests (PLTs) were carried out on a sandy soil both under saturated and unsaturated conditions. Based on these studies, a semi-empirical equation has been proposed for estimating the variation of bearing capacity with respect to matric suction. The saturated shear strength parameters and the soil water characteristic curve (SWCC) are required for using the proposed equation. This equation is consistent with the bearing capacity equation originally proposed by Terzaghi (1943) and later extended by Meyerhof (1951) for saturated soils. Chapter 2 provides the details of these studies.
The cone penetration test (CPT) is conventionally used for estimating the bearing capacity of foundations because it is simple and quick, while providing continuous records with depth. In this research program, a cone penetrometer was specially designed to investigate the influence of matric suction on the cone resistance in a controlled laboratory environment. Several series of CPTs were conducted in sand under both saturated and unsaturated conditions. Simple correlations were proposed from CPTs data to relate the bearing capacity of shallow foundations to cone resistance in saturated and unsaturated sands. The details of these studies are presented and summarized in Chapter 3.
Standard penetration tests (SPTs) and PLTs were conducted in-situ sand deposit at Carp region in Ottawa under both saturated and unsaturated conditions. The test results from the SPTs and PLTs at Carp were used along with other data from the literature for developing correlations for estimating the bearing capacity of both saturated and unsaturated sands. The proposed SPT-CPT-based technique is simple and reliable for estimation of the bearing capacity of footings in sands. Chapter 4 summarizes the details of these investigations.
Empirical relationships were proposed using the CPTs data to estimate the modulus of elasticity of sands for settlement estimation of footings in both saturated and unsaturated sands. This was achieved by modifying the Schmertmann et al. (1978) equation, which is conventionally used for settlement estimations in practice. Comparisons are provided between the three CPT-based methods that are commonly used for settlement estimations in practice and the proposed method for seven large scale footings in sandy soils. The results of the comparisons show that the proposed method provides better estimations for both saturated and unsaturated sands. Chapter 5 summarizes the details of these studies.
A Flexible Laminar Shear Box (FLSB of 800-mm3 in size) was specially designed and constructed to simulate and better understand the behaviour of model surface footing under seismic loads taking account of the influence of matric suction in an unsaturated sandy soil. The main purpose of using the FLSB is to simulate realistic in-situ soils behaviour during earthquake ground shaking. The FLSB test setup with model footing was placed on unidirectional 1-g shake table (aluminum platform of 1000-mm2 in size) during testing. The resistance of unsaturated sand to deformations and liquefaction under seismic loads was investigated. The results of the study show that matric suction offers significant resistance to liquefaction and settlement of footings in sand. Details of the equipment setup, test procedure and results of this study are presented in Chapter 6.
Simple techniques are provided in this thesis for estimating the bearing capacity and settlement behaviour of sandy soils taking account of the influence of capillary stresses (i.e., matric suction). These techniques are consistent with the methods used in conventional geotechnical engineering practice. The studies show that even low values of capillary stresses (i.e., 0 to 5 kPa) increases the bearing capacity by two to four folds, and the settlement of footings not only decreases significantly but also offers resistance to liquefaction in sands. These studies are promising and encouraging to use ground improvement techniques; such as capillary barrier techniques to maintain capillary stresses within the zone of influence below shallow foundations. Such techniques, not only contribute to the increase of bearing capacity, they reduce settlement and alleviate problems associated with earthquake effects in sandy soils.
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Zboranová, Monika. "Novostavba domova dôchodcov." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2016. http://www.nusl.cz/ntk/nusl-240125.
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The project deals with structure design of a new – built house for elderly with accommodation capacity up to 28 persons. It is situated on the south side of the village Papradno in a flat lot with area of 6018,4 m2.The house for elderly was designed for disabled people, it has got two floors with irregular shape and the floor area of 920,83 m2 . On the first floor there is an accommodation part of building situated on the southwest side and there is an another part of building where are situated rooms like (kitchen for serving meals, dining room, boiler room, changing room for employee...) it is situated on the northeast side. On the second floor there is an accommodation part of building it is identical as in the first floor. And the another part of second floor it has got rooms like (offices, storages, chapel, club room...). A bearing system composed of uninforcement concret foundation, wall system of ceramic block Porotherm and the slab system composed of bearing panels Spiroll. The Spiroll panels is a bearing system for flat roof with clasic layer order.
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Hossain, Muhammad Shazzad. "New mechanism-based design approaches for spudcan foundations in clay." University of Western Australia. School of Civil and Resource Engineering, 2009. http://theses.library.uwa.edu.au/adt-WU2009.0103.
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[Truncated abstract] Three-legged mobile jack-up rigs supported on spudcan foundations are used to perform most offshore drilling in shallow to moderate water depths, and are now capable of operating in water depths up to 130 m. With the gradual move towards heavier rigs in deeper water, and continuing high accident rates during preloading of the spudcan foundations, appraisal of the performance and safety of jack-up rigs has become increasingly important. A crucial aspect of this is to improve understanding of the mechanisms of soil flow around spudcan foundations undergoing continuous large penetration, and to provide accurate estimates of spudcan penetration resistance, avoiding excessive conservatism. Spudcan foundations undergo progressive penetration during preloading, contrasting with onshore practice where a footing is placed at the base of a pre-excavated hole or trench. However, spudcan penetration is generally assessed within the framework used for onshore foundations, considering the bearing resistance of spudcans pre-placed at different depths within the soil profile. The lack of accurate design approaches that take proper account of the nature of spudcan continuous penetration, which is particularly important in layered soil profiles, is an important factor in the high rate of accidents. ... It was found that when a spudcan penetrated into single layer clay, there were three distinct penetration mechanisms: during initial penetration, soil flow extended upwards to the surface leading to surface heave and formation of a cavity above the spudcan; with further penetration, soil began to flow back gradually onto the top of the spudcan; during deep penetration, soil back-flow continued to occur while the initial cavity remained unchanged. For spudcan penetration in stiff-over-soft clay, four interesting aspects of the soil flow mechanisms were identified: (a) vertically downward motion of the soil and consequent deformation of the layer interface; (b) trapping of the stronger material beneath the spudcan, with this material being carried down into the underlying soft layer; (c) delayed back-flow of soil around the spudcan into the cavity formed above the spudcan; (d) eventual localised flow around the embedded spudcan, surrounded by strong soil. At some stage during continuous spudcan penetration, the soil starts to flow back into the cavity above the spudcan. The resulting back-flow provides a seal above the penetrating spudcan and limits the cavity depth. It was shown that the current offshore design guidelines are based on the wrong criterion for when back-flow occurs. New design charts with robust expressions were developed to estimate the point of back-flow and hence the cavity depth above the installed spudcan. Load-penetration responses were presented in terms of normalised soil properties and geometry factors for both single layer and two-layer clay profiles, taking full account of the observed flow mechanisms. Further, guidelines were suggested to evaluate the likelihood and severity of spudcan punch-through failure in layered clays. Finally, the effect of strain-rate and strain-softening was examined, in an attempt to model real soil behaviour more closely. Adjustment factors were proposed to modify the design approaches developed on the basis of ideal elastic-perfectly plastic soil behaviour.
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Oktay, Emre Hasan. "Finite Element Analysis Of Laboratory Model Experiments On Behavior Of Shallow Foundations Under General Loading." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614210/index.pdf.
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In this study, a series of laboratory model experiments carried on shallow foundations is intended to be simulated through numerical modeling. The laboratory model tests were conducted by Fukui et al. (2005), over square shaped, shallow surfacial foundations located over air-dried Toyoura sand. Tests included centered vertical and combined loading cases on sand with 60% and 80% relative densities. Plastic limit loads obtained from numerical analyses and available analytical solutions in literature are compared to the laboratory test results and the differences are discussed.
Employment of Mohr - Coulomb yield criterion and linear elasticity, resulting in linear elastic perfectly plastic constitutive law, is one of the most common practices in modeling geotechnical problems. Accuracy of this approach for the modeled experiments is judged by comparison of analyses results with experimental findings and solutions in literature. Finite element method is utilized for modeling purposes, with Mohr-Coulomb yield criterion and linear elastic behavior. Abaqus 6-10.2 is selected as the analysis software, and two and three dimensional models are used in the analyses. Analyses, the results of which are compared with experimental findings, aim employment of associated flow rule. Additional analyses are conducted with varying dilation angles in order to examine the influence of unassociated flow rule on eccentric and concentric loading results.
Differences between the results of numerical analyses and experimental observations varied between 2% and 34%. Main reason of the difference is attributed to employed soil behavior modeling approach in analyses and the eccentric placement of model weight in monotonic horizontal loading experiments. In the case when this eccentric placement is accounted for in numerical models, it is seen that the difference diminished to vary between 8% and 18%, and order of the difference was similar for similar experiment cases. Therefore, based on this condition, it is seen that results of the modeled experiments are consistent, while in general they are somewhat higher than the results obtained from analyses and solutions in literature. Difference between the results of analyses and average of selected solutions in literature in both cases is at most 9%.
Finite element method employing Mohr-Coulomb failure criterion could provide results in close agreement with solutions in literature that inherently assume Mohr-Coulomb failure criterion as well. However, the same accuracy could not be obtained for experiments due to uncertainties involved in the material properties as well as the insufficiencies of the model to represent the behavior precisely. Finite element method has the potential to consider more advanced material models. Nonetheless, employment of Mohr-Coulomb failure criterion provides results with sufficient accuracy for most cases.
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Lee, Kok Kuen. "Investigation of potential spudcan punch-through failure on sand overlying clay soils." University of Western Australia. School of Civil and Resource Engineering, 2009. http://theses.library.uwa.edu.au/adt-WU2009.0212.
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When a jack-up foundation is installed on seabeds consisting of a sand layer overlying soft clay, potential for 'punch-through' failure exists. This happens due to an abrupt reduction in bearing resistance when the foundation punches a block of sand into the underlying soft clay in an uncontrolled manner. This can lead to a sudden large penetration that can cause temporary decommissioning and even toppling of the unit. This research has addressed this problem with the aim of developing a practical design method for the jack-up industry to assess potential punch-through hazards. This objective has been achieved with the successful development of a new conceptual model for predicting the peak penetration resistance and a consistent method for constructing a complete resistance profile of spudcan foundations penetrating through sand into the underlying clay. The analytical basis of the new conceptual model follows the approach for silo analysis, and takes into account the stress level and dilatant response of sand. It is therefore a significant improvement over the punching shear and load spread models recommended in the current industry guidelines SNAME (2002), which do not consider the strength properties of the sand. To provide relevant experimental data for the new model, an extensive series of 30 continuous penetration tests were performed using the UWA drum centrifuge. These experimental results were retrospectively simulated using finite element (FE) analysis, in order to back-calculate the stress-level dependent friction and dilation angles in the sand during peak penetration resistance. The back-analysis showed that larger values of peak resistance gave lower friction and dilation angles, which is consistent with gradual suppression of dilatancy under high confining stress. When compared to published results from visualisation experiments, the FE analysis showed a similar failure mechanism during peak resistance, where a frustum of sand was forced into the underlying clay, with the outer angle reflecting the dilation in the sand. This has formed the basis of the new conceptual model. The performance of the new model in predicting the experimental peak resistance was compared with other existing analytical methods. Additional experimental results, including those already in the literature, were incorporated in the comparative study. It was found that the new conceptual model generally gave a good prediction of the experimental values, while the prediction from SNAME (2002) was conservative, with the predicted values being about half the experimental results on average. It was also shown that the new model could be modified to predict the post-peak penetration resistance in the sand layer. Finally, an analytical method for predicting the resistance profiles in the underlying clay was devised based on new bearing capacity factors developed through FE analysis. By joining the values of peak resistance, post-peak resistance and the resistance profile in the underlying clay, a complete simplified penetration resistance profile for spudcan foundations in sand overlying clay can be generated. The predicted profiles were shown to match the experimental results well.
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Foppa, Diego. "Novo método para cálculo da capacidade de carga de fundações superficiais assentes sobre camada de reforço em solo cimento." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2016. http://hdl.handle.net/10183/156817.
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Pesquisas recentes têm mostrado que a utilização de camada de reforço em solo-cimento é uma alternativa para o aumento da capacidade de carga e redução dos recalques de fundações superficiais em solos de baixa resistência. Os métodos para previsão da capacidade de carga em sistemas de dupla camada encontrados na literatura trazem implícita a premissa de que a camada superior é contínua ou suficientemente maior que a largura da fundação. O objetivo desta pesquisa foi desenvolver um novo método para o cálculo de capacidade de carga de fundações superficiais assentes sobre uma camada de reforço em solo-cimento, considerando sua extensão lateral. Para tanto, foram realizados ensaios em modelos reduzidos de fundações contínuas assentes sobre um solo arenoso fofo, bem como, análises numéricas através do método dos elementos finitos. Observaram-se dois tipos distintos de ruptura. No primeiro, a camada de reforço é puncionada para dentro do solo natural, sem apresentar fissuras, até o deslocamento correspondente à capacidade de carga do solo natural No segundo, após um recalque inicial, a camada de reforço rompe com o aparecimento de uma fissura, que pode localizar-se junto à borda ou no eixo da fundação, e se propaga de baixo para cima, à medida que aumentam os recalques. Verificou-se que a máxima tensão de tração na camada de reforço é função da reação do solo na base do reforço e da relação Tr/Hr, onde Tr é a distância horizontal entre a borda da fundação e a borda do reforço e Hr é a espessura do reforço. A partir destas observações, foi desenvolvido um novo método de cálculo com a premissa de que a ruptura ocorra no solo e não na camada de reforço. Assim, é possível calcular a capacidade de carga considerando que fundação e reforço atuam como um elemento único, apoiado na mesma profundidade de assentamento do reforço. Ao mesmo tempo, é apresentada uma equação para previsão da máxima tensão de tração que atuará no reforço, a partir da qual, se pode dimensioná-lo com segurança.<br>Recent researches have shown that the use of soil-cement reinforcement layer is an alternative to increase bearing capacity and reduce settlements of shallow foundations in low resistance soils. The existing methods for predicting bearing capacity of double layer systems implicitly assume that the top layer is continuous or sufficiently greater than the foundation width. This study aims to develop a new method for bearing capacity calculation of shallow foundations supported by a soil-cement reinforcing layer, considering its lateral extension. Therefore, small scale tests of continuous foundations on a loose sandy soil, as well as, numerical analysis by the finite element method were carried out. It was observed two distinct types of failure. In the first, the reinforcement layer is punched through the sandy soil, without showing any cracking, up to a settlement which corresponds to the sand bearing capacity. In the second, after an initial settlement, the reinforcement layer breaks up, showing a fissure, which may be located near the edge or the axis of foundation, and propagates upward as the settlements continues. It was found that the maximum tensile stress in the reinforcement layer is a function of soil reaction on the reinforcement and the ratio Tr/Hr, where Tr is the horizontal distance between the edge of the foundation and the edge soil-cement layer and Hr is the thickness of the soil-cement layer. From these observations, it was developed a new calculation method, with the assumption that the failure occurs in the soil and not in the reinforcement layer. Thus, it is possible to calculate the bearing capacity considering that foundation and reinforcement act as a single element, supported at the same depth of the reinforcement base. In order to design the soil-cement layer, an equation for the maximum tensile stress prediction is provided.
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Scallet, Marcella Maschietto. "Comportamento de estacas escavadas de pequeno diâmetro em solo laterítico e colapsível da região de Campinas/SP." [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/257684.
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Orientador: Miriam Gonçalves Miguel<br>Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo<br>Made available in DSpace on 2018-08-17T14:10:40Z (GMT). No. of bitstreams: 1
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Previous issue date: 2011<br>Resumo: Este trabalho tem como objetivo estudar o comportamento de estacas escavadas de pequeno diâmetro, submetidas a carregamentos axiais de compressão através de provas de carga estática realizadas no Campo Experimental de Mecânica dos Solos e Fundações 2 da Unicamp. O CEMSF2 apresenta um perfil geológico cuja primeira camada é constituída de argila siltosa, coluvionar, laterítica e colapsível. Pretendeu-se avaliar as capacidades de carga e os recalques dessas estacas nas condições: a) sem pré-inundação e sem melhoria de ponta; b) sem pré-inundação e com melhoria de 1 ponta, com o lançamento de um volume de 18 litros de brita 1 no fundo da estaca antes da concretagem; c) com pré-inundação e sem melhoria de ponta e d) com préinundação e com melhoria de ponta. Todas as estacas foram submetidas a dois carregamentos (ensaios e reensaios), sob uma mesma condição acima descrita. Foram instalados tensiômetros convencionais para a leitura das sucções matriciais do solo durante a realização das provas de carga. Através das curvas carga versus recalque foram definidas as capacidades de carga e as resistências ao atrito lateral e de ponta, por meio de métodos de interpretação dessas curvas com o solo sem inundação e préinundado por 48horas, considerando as reduções dos valores da sucção matricial do solo, devido às duas condições de umidade. A capacidade de carga das estacas nos ensaios foi menor do que nos reensaios, para as estacas sem pré-inundação, devido ao aumento da resistência de ponta nos reensaios. Nas provas de carga com préinundação, em geral, não houve aumento de resistência de ponta dos ensaios para os reensa ios. A resistência ao atrito lateral foi maior que a resistência de ponta em todas as provas de carga. O lançamento de brita 1 não trouxe melhorias na capacidade de carga. Reduções consideráveis na capacidade de carga foram observadas em função da pré-inundação do solo, sendo essas reduções mais expressivas para as estacas com melhoria de ponta<br>Abstract: This paper aims to study the behavior of bored piles of small diameters, subjected to axial compression loads by static load tests carried out at the Field of Experimental Soil Mechanics and Foundation 2 at Unicamp. The CEMSF2 has a geological profile whose first layer is composed of silty clay, with coluvionar, lateritic, and collapsible features.This study intended to evaluate the load capacities and the settlements of these foundations in such conditions: a) without any pre- wetting nor improvement in the tip; b) without any pre-wetting but with a tip improvement, placing a volume of 18 liters of stones 1 in the base of the pile before concreting c) with pre- wetting but without tip improvement and d) with pre-wetting and tip improvement. All these piles were subjected to two loading (tests and retests), under the same test condition described above. Conventional tensiometers were installed to read the matric suctions of the soil during the performance of the load tests. Throughout the load versus settlement curves the load capacities and the strength to lateral friction and tip were defined using methods of interpretation of these curves with the soil without any pre-wetting and 48-hour-pre wetting, considering the reductions of the values of the soil matric suction due to two moisture conditions. The load capacity of piles in the tests was smaller than the one in the retests for the piles without any pre-flooding, due to the increase of the tip strength in the retests. In the load tests with pre-flooding, in general, there was not any increase of strength in the tip of the tests for the retests. The strength to the lateral friction was greater than the tip strength in all loading tests. The placing stones 1did not result any improvement to the bearing capacity. Considerable reductions in bearing capacity were observed because of the pre-wetting soil, such reductions are more significant for the piles with improved tip<br>Mestrado<br>Geotecnia<br>Mestre em Engenharia Civil
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Raja, Muhammad Nouman Amjad. "Load-settlement investigation of geosynthetic-reinforced soil using experimental, analytical, and intelligent modelling techniques." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2021. https://ro.ecu.edu.au/theses/2455.
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During the past five decades, numerous studies have been conducted to investigate the load-settlement behaviour of geosynthetic-reinforced soil. The main advantage of reinforced soil foundations are the increase in the bearing capacity and decrease in the settlement. Whereas, for pavement foundation design, the strength of the subgrade soil is often measured in terms of California bearing ratio (CBR). The researchers have suggested various methods to improve the quality of geosynthetic-reinforced foundations soils. In the recent past, the wraparound geosynthetic reinforcement technique has been proposed to strengthen the foundation soil effectively. However, there are several research gaps in the area; for example, there has been no analytical solution for estimating the ultimate bearing capacity of wraparound reinforced foundations, and there has been no evaluation of this technique under repeated loading conditions. Similarly, for planar geosynthetic-reinforced soil foundations, the prediction of load-settlement behaviour also requires more attention. The advent of artificial intelligence (AI) based modelling techniques has made many traditional approaches antiquated. Despite this, there is limited research on using AI techniques to derive mathematical expressions for predicting the load-settlement behaviour of reinforced soil foundations or the strength of reinforced subgrade soil.
This research is undertaken to examine the load-settlement behaviour of geosynthetic-reinforced foundation soils using experimental, analytical, and intelligent modelling methods. For this purpose, extensive laboratory measurements, analytical, numerical and AI-based modelling and analysis have been conducted to: (i) derive theoretical expression to estimate the ultimate bearing capacity of footing resting on soil bed strengthened by wraparound reinforcement technique; (ii) using detail experimental study, present the effectiveness of wraparound reinforcement for improving the load-settlement characteristics of sandy soil under repeated loading conditions; (iii) to build the executable artificial intelligence-based or computationally intelligent soft computing models and converting them into simple mathematical equations for estimating the (a) ultimate bearing capacity of reinforced soil foundations; (b) settlement at peak footing loads; (c) strength (California bearing ratio) of geosynthetic-reinforced subgrade soil; and (iv) to examine and predict the settlement of geosynthetic-reinforced soil foundations (GRSF) under service loading condition using novel hybrid approach, that is, finite element modelling (FEM) and AI modelling.
In the analytical phase, a theoretical expression has been developed for estimating the ultimate bearing capacity of strip footing resting on soil bed reinforced with the geosynthetic layer having the wraparound ends. The wraparound ends of the geosynthetic reinforcement are considered to provide the shearing resistance at the soil-geosynthetic interface as well as the passive resistance due to confinement of soil by the geosynthetic reinforcement. The values of ultimate load-bearing capacity determined by using the developed analytical expression have predicted values closer to the model studies reported in the literature, with a difference in the range of 0% to 25% with an average difference of 10%.
In the experimental phase, model footing load tests have been conducted on strip footing resting on a sandy soil bed reinforced with geosynthetic in wraparound and planar forms under monotonic and repeated loadings. The geosynthetic layers were laid according to the reinforcement ratio to minimise the scale effect. The effect of repeated load amplitude and the number of cycles, and the effect of reinforcement parameters, such as number of layers, reinforcement width, lap-length ratio and planar width of wraparound, were investigated, and their potential effect on the load-settlement behaviour has been studied. The wraparound reinforced model has shown about 45% lower average total settlement than the unreinforced model. In comparison, the double-layer reinforced model has about 41% at the cost of twice the material and 1.5 times the occupied land width ratio. Additionally, for lower settlement levels (s/B ≤ 5%), the wraparound geotextile with a smaller occupied land width ratio (bp/B = 3.5) has performed well in comparison to the wraparound with a slightly larger occupied land width ratio (bp/B = 4). However, the wraparound with occupied width ratio of 4 provides more stability to the foundation soil for higher settlement levels. The performance of the fully wrapped model (bp/B = 2.8) is more similar to that of the planar double-layer reinforced model (b/B = 4); however, it is noted that even the fully wrapped model outperforms the planar single-layer reinforced model with the same amount of geotextile and 50% less occupied land width
For data analytic methods, first historical data has been collected to build the various machine learning (ML) models, and then detailed comparison has been presented among the ML-based models and with other available theoretical methods. A comprehensive study was conducted for each model to choose its structure, optimisation, and tuning of hyperparameters and its interpretation in the form of mathematical expressions. The forecasting strength of the models was assessed through a cross-validation approach, rigorous statistical testing, multi-criteria approach, and external validation process. The traditional statistical indices such as coefficient of determination (R2), root mean square error (RMSE), mean absolute error (MAE), and mean absolute percent deviation (MAPD); along with several other modern model performance indicators, were utilised to evaluate the accuracy of the developed models. For ultimate bearing capacity (UBC) estimation, the performance of the extreme learning machine (ELM) and TreeNet models has shown a good degree of prediction accuracy in comparison with traditional methods over the test dataset. However, the overall performance of the ELM model (R2 = 0.9586, MAPD=12.8%) was better than that of the TreeNet model (R2 = 0.9147, MAPD =17.2%). Similarly, for settlement estimation at peak footing loads, multivariate adaptive regression splines (MARS) modelling technique has outperformed (R2 = 0.974, RMSE = 1.19 mm, and MAPD = 7.19%) several other robust AI-based models, namely ELM, support vector regression (SVR), Gaussian process regression (GPR), and stochastic gradient boosting trees (SGBT). For CBR, the competency and reliability of the several intelligent models such as artificial neural network (ANN), least median of squares regression (LMSR), GPR, elastic net regularization regression (ENRR), lazy K-star (LKS), M5 model trees, alternating model trees (AMT), and random forest (RF). Among all the intelligent modelling techniques, ANN (R2 = 0.944, RMSE = 1.74, and MAE = 1.27) and LKS (R2 = 0.955, RMSE = 1.52, and MAE = 1.04) has achieved the highest ranking score of 35 and 40, respectively, in predicting the CBR of geosynthetic-reinforced soil. Moreover, for UBC and settlement at peak footing loads, new model footing load tests, and for strength of reinforced subgrade soil, new CBR tests were also conducted to verify the predictive veracity of the developed AI-based models.
For predicting the settlement behaviour of GRSF under various service loads, an integrated numerical-artificial intelligence approach was utilised. First, the large-scale footing load tests were simulated using the FEM technique. At the second stage, a detailed parametric study was conducted to find the effect of footing-, geosynthetic- and soil strength- parameters on the settlement of GRSF under various service loads. Afterward, a novel evolutionary artificial intelligence model, that is, grey-wolf optimised artificial neural network (ANN-GWO), was developed and translated to the simple mathematical equation for estimating the load-settlement behaviour of GRSF. The results of this study indicate that the proposed ANN-GWO model predict the settlement of GRSF with high accuracy for training (RMSE = 0.472 mm, MAE = 0.833, R2 = 0.982), and testing (RMSE = 0.612 mm, MAE = 0.363, R2 = 0.962,) dataset. Furthermore, the predictive veracity of the model was verified by detailed and rigorous statistical testing and against several independent scientific studies as reported in the literature.
This work is practically valuable for understanding and predicting the load-settlement behaviour of reinforced soil foundations and applies to traditional planar geosynthetic-reinforced and as well as recently developed wraparound geosynthetic-reinforced foundation soil technique. For wraparound reinforced soil foundations, the analytical expression will be helpful in the estimation of ultimate bearing capacity, and experimental study shows the beneficial effects of such foundations systems in terms of enhancement in bearing capacity and reduction in the settlement, and economic benefits in terms of saving land area and amount of geosynthetic, under repeated loading conditions. Moreover, the developed AI-based models and mathematical expressions will be helpful for the practitioners in predicting the strength and settlement of reinforced soil in an effective and intelligent way and will be beneficial in the broader understanding of embedding the intelligent modelling techniques with geosynthetic-reinforced soil (GRS) technology for the automation in construction projects.
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Vianna, Ana Paula Fontana. "Influência da dimensão e da sucção matricial no comportamento de fundações superficiais assentes em solo arenoso não-saturado." Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/18/18132/tde-28042006-100500/.
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Analisa-se a influência da sucção matricial e da dimensão de sapatas na capacidade de carga e nos recalques de fundações rasas, assentes em areia não-saturada. Na primeira parte da pesquisa foram analisadas 14 provas de carga estática em placas metálicas rígidas assentes a 1,5 m de profundidade, com diâmetros de 0,20, 0,40 e 0,80m e em uma sapata circular de concreto com diâmetro de 1,50 m, no campo experimental de fundações da USP/São Carlos. Devido ao caráter colapsível do solo, a sucção matricial foi monitorada por meio de tensiômetros instalados no fundo da cava. Na segunda parte da pesquisa, foram realizados ensaios em centrífuga, na Universidade do Colorado em Boulder, utilizando-se placas metálicas de 30 mm, 50 mm e 100 mm, ensaiadas a 1 g, 5 g, 10 g, 15 g, 25 g, 50 g e 100 g. As placas foram assentes em maciço de areia em três condições de umidade: seca, inundada e não-inundada. A partir dos resultados obtidos, procedeu-se a análise da capacidade de carga levando-se em conta tanto o efeito da dimensão como o da sucção matricial. A influência da dimensão nos recalques também foi analisada. Ratificou-se que o aumento da sução matricial provoca um aumento substancial na capacidade de carga do sistema placa-solo e uma diminuição considerável nos recalques. Em relação à influência da dimensão no comportamento de fundações rasas, demonstrou-se que tanto a variação da capacidade de carga como a dos recalques não ocorre de forma linear e crescente como apresentado pelos métodos teóricos. Para pequenas dimensões da sapata, os valores de capacidade de carga e recalque aumentam<br>The influence of matric suction and size of footings in the bearing capacity and settlement of shallow foundations in unsaturated sandy soils are analyzed. Fourteen plate load tests were performed in the first part of the research. Rigid metallic plates with diameters 0,20, 0,40, 0,80 m and one concrete circular footing with 1,50 m were used in the tests. All plates and footing were positioned at 1,50 m depth. The tests were performed in the foundation experimental field of USP/São Carlos. Due to the soil collapsible character, the tests were performed with the monitoring of matric suction pressure through tensiometers installed in the bottom of the holes. Centrifuge tests were carried out at the University of Colorado at Boulder in the second part of the research. Metallic plates with 30 mm, 50 mm and 10 mm were used and the gravity levels were 1 g, 5 g, 10 g, 15 g, 25 g, 50 g e 100 g. The plates were positioned on top of a sandy soil with three moisture conditions: dry, flooded and non-flooded. Thus, the capacity will be analyzed taking into consideration both the geometry of the tested plates and the influence of the matric suction pressure. The footing size influence in the settlement was also analyzed. A substantial increase of the plate-soil system bearing capacity and a considerable decrease in the settlements, caused by matric suction increase, was confirmed. It was also demonstrated that the bearing capacity and settlements variations are not a linearly increasing function of the size as theoretical methods suggest. For small footings, the bearing capacity and settlement increase as the footing size decreases
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Ilčík, David. "Železobetonová konstrukce bytového domu." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2016. http://www.nusl.cz/ntk/nusl-240070.
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The diploma thesis is aimed for design and assessment main load bearing elements of a apart-ment building on the ultimate and serviceability limit state. Assessed parts of construction are reinforced concrete slab over the second floor, column and shear wall in the first floor, stairway slab and foundation pad. The elements are assessed in a structural design report according valid standard. There is created drawings. Internal forces are calculated using software Scia Engineer, where is modeled and loaded the construction.
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Štramberský, Martin. "Návrh předpjaté nádrže." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2014. http://www.nusl.cz/ntk/nusl-226967.
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The matter of this diploma thesis is a static storage tank for petroleum substances, the study of a solution for appropriate shape of shell and its effort to dihedral for roofing, and the study of effect of the storage of inner roofs walls of the tank to the size of the internal forces. The internal walls are carried out by the method of finite elements in the engineering program Scia Engineering 2013 and on the basis of it, designing of the framing sections of the tank. There is a calculation part of the lower horizontal bias wreaths of the shell and internal supporting wall. All the components are assessed on the 1st limit state of the load-bearing capacity and the 2nd limit state of the application (emergence cracks, limiting voltage in the concrete and a prestressing steel). The existing external wall is assessed only on the marginal status load of carrying capacity. The part of diploma thesis is also drawing documentation, accompanying report and technical report. The goal of the diploma thesis was to design the tank without an occurrence of the cracks in the concrete so as the vertical wall was prestressing only in the horizontal direction and the optimal proposal roof tanks as an addition.
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Kondáš, Ondřej. "Polyfunkční dům Brno, Černovice - stavebně technologický projekt." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-265233.
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The aim of this master's thesis is the construction-technological project of the entire building focusing on major construction building - Multifunctional house, which is based on large-diameter piles. The main part of thesis are budget of object and time schedules of construction. Part of the thesis is organization of construction and design of the site eguipment, technological regulation of selected work, quality control and solving transport relations including oversize cargo. It also deals with the design of mechanical assemblies, health and safety, safety of environment and design of instructions for use of building.
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Ip, Kai Wing. "Bearing capacity for foundation near slope." Thesis, 2005. http://spectrum.library.concordia.ca/8784/1/MR14249.pdf.
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The bearing capacity of the foundation is a primary concern in the field of foundation engineering. The self weight of the structure and the applied loads are transferred to the soil safely and economically. The load at which the shear failure of the soil occurs is called the ultimate bearing capacity of the foundation. Quite often, structures are built on or near a slope. This is due to land limitation, such as for bridges or for architectural purposes. The ultimate bearing capacity of the foundations for these buildings is significantly affected by the presence of the slope. Design of foundations under these conditions is complex and the information available in the literature is limited. A numerical model was developed to simulate the case of strip foundation near slope, using the finite element technique together with the program "PLAXIS". The parameters believed to govern this behavior were examined individually to determine their effect on the ultimate bearing capacity of a strip footing. The superposition method was used in the analyses to calculate the bearing capacity factors, N c , N q , and N Þ , independently. The results produced by the present numerical model were compared with the available experimental data. An analytical model was also developed for the problem stated to predict the ultimate bearing capacity of a strip footing. Design theory, design procedure and design charts are presented for practical use
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Yu, Hsing-Yun, and 游欣運. "Inclined Bearing Capacity of Shallow Foundation." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/29521479766462762870.
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碩士<br>淡江大學<br>土木工程研究所<br>81<br>This research attempts to establish a new analytical method to calculate the bearing capacity factors No, Nq and Nr of shallow foundations under inclined loads and the ultimate bearing capacity quit .This method is based on Terzaqhi's failure mechanism(assuming the failure surface under a shallow foundation is a combination of a logarthmic spiral curve and a straight line). The Rankine's theory of passive earth pressure , and the method of moment equili-brium are utilized in the limited equilbrium analysis.
The results show that, in the case of vertical loads, the values of the bearing capacity factors Nc, Nq obtained by this method is approximately the same as of Terzaghi(1943), Prakash and Saran (1971), Saran(1971), Narita and Yamaguchi(1989), and Saran and Agarwal(1991); howrvrt, they are larger than that of Caquot-Kerisel(1949), Meyerhof(1951), Sokolovski(1965) and Chen(1975). As far as the Nr is concerned, the values are similar to that of prakash and Saran(1971) but smaller than that of Saran(1971), Chen(1975), Narita and Yamaguchi(1989), and saran and Agarwal(1991).
In the case of strip foundation under inclined loads, the theoretical values agree fairly well with Meyerhof's experimental values(1953, 1980, 1981). And when compared with all the experimen-tal data from literature, the theoretical values of the ultimate bearing capacity of anyfoundation using a modified Terzaghi's shape factors also agree approximately Meyerhof's laboratory data.
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Wang, Cheng-Guang, and 王程廣. "Preliminary Study of Bearing Capacity of Shallow Foundation on Reinforced SoilPreliminary Study of Bearing Capacity of Shallow Foundation on Reinforced SoilPreliminary Study of Bearing Capacity of Shallow Foundation on Reinforced Soil." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/74500852488759345197.
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碩士<br>國立宜蘭大學<br>土木工程學系碩士班<br>95<br>Adding geosynthetics into soil has been widely used for Geotechnical Engineering for a long time;however, the interface between soil and geosynthetics still contains a lot of unknowns, which we need to study moreto have better understanding. Langyang Plain contains weak soil with high proportion of fine particulates. Typical problems such as insufficient bearing capacity and excessive settlement always happen when shallow foundation constructed. Thus, the original idea of this proposal comes to mind - utilizing geosynthetics to improve the bearing capacity of shallow foundation on weak soil.
First, this research employs the theory developed by Terzaghi for the bearing capacity of shallow foundation. The proposed bearing capacity equation of reinforced shallow foundation considers tension, shear, and pull out failures, which lead to different consequences of bearing capacity. The reinforced soils are sand and clay. In this research, it is found that to reinforce in clayey soil can get better effect than in sandy soil. In addition, reinforced depth is lesser in small friction angle soil than big friction angle soil.
In the laboratory, two kinds of soils (sand and clay) are used for the bearing capacity test. The testing results are recorded (both the bearing capacity and the settlement) to compare the influence between reinforced soil and non-reinforced(??) soil. It is found that to reinforce in clay leads to a better result than in sand. The field bearing capacity test, which use geosynthetics on the subgrade of road, comes out a remarkable result of bearing 8 tons by weight.
In this research, we also simulate the laboratory test and field test by PLAXIS finite element program. PLAXIS is used to model the laboratory test with two different soils (clay and sand) first. After that, the PLAXIS is used again to simulate the field test for different backfill depth. reinforcing in the clayey soil has a better result than in the sandy soil. The simulated result of reinforced field test shows that the required depth of backfill material is 50cm, which is also similar to field test results.
Parametric study shows that the effect of layer number is important for bearing capacity and settlement control. On ther other hand, the lesser depth of reinforcement layer comes out lesser amount of settlement. Besides, the effect of reinforcement depth is more obvious than of layer number on settlement control.
This research verifies that reinforced shallow foundation can provide higher bearing capacity and smaller settlement??. In addition, it is also found that reinforcing on weak soil can provide better effect of bearing capacity than on strong soil. Thus, geosynthetics is suitable for solving the problem of insufficient bearing capacity of shallow foundation on weak soil.
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WANG, MENG-YI, and 王孟熙. "Bearing capacity of shallow foundation adjacent to slope." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/82905615610397023732.
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Kuo, Ming-Wei, and 郭明瑋. "Numerical Analysis on Bearing Capacity of Foundation over Slope." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/34436492102448187416.
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碩士<br>國立中央大學<br>土木工程研究所<br>92<br>In this study, FLAC is applied to numerically simulate the behavior of foundation bearing mechanism over horizontal ground and slope. The effect of reduced bearing capacity due to slope is analyzed with slope angles of 10°, 20°, and 30°. Design chart with bearing capacity factors and reducing factor for slope is introduced for applications. The concept of reducing factor is to normalize the bearing capacity factors for horizontal ground with those for slope.
The parameters for numerical analysis are: height and slope angle for slopes; position and embedded depth for foundations; friction angle, dilation angle and cohesion for soil material properties. Combinations of parameters under different slope angles are studied to evaluate the effect of reducing factor.
When a foundation is placed on the edge of a slope, bearing capacity decreases with slope height increases till critical height (Hcr) is reached. Under this circumstance, the effect of reduced bearing capacity due to slope is maximized and the bearing capacity retains a constant no matter how the height of slope increases beyond Hcr . For the effect of foundation relative position, the reducing factors, αγs, αcs and αqs increase with the increasing of distance between edge of a slope and foundation . The critical distance, beyond which the slope effect no longer exists, increases with the increasing of friction angle and slope angle. Above relationships are mainly affected by slope angle and friction angle, but not obvious by dilation angle.
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B, aruah N. irupam. "A study on Bearing Capacity of Submerged Rock Foundation." Thesis, 2014. http://ethesis.nitrkl.ac.in/5524/1/212CE1021-13.pdf.
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For more urbanization, engineering structures are not limited to underground tunnels or metro stations, engineers are constructing underground multistoried building even underground city. Therefore accurate assessment of rock strength is necessary for the rational design of underground structures. Bearing capacity is one of the most important factor for assessment of rock strength. Various studies on determination of bearing capacity for intact as well as jointed rock mass have been performed. Concisely, various studies have been performed for determination of bearing capacity of rock mass under dry condition while for submerged condition, it is outnumbered. In this study, determination of submerged bearing capacity of rock mass is attempted. Most cases, the rock substratum is considered to be homogeneous, intact, but the practical scenario does not recommend so. In-situ rock mass variability renders the deterministic analysis to be inefficient and hence there arises the necessity for probabilistic or reliability analyses to model the uncertainties. Rather than calculating a deterministic factor of safety, a reliability based analysis is more appropriate for geotechnical design. Present study comprises of different aspects regarding ultimate bearing capacity of rock foundations for both dry and submerged condition. These are, development of algorithmic modelling for determination of ultimate bearing capacity for both dry and submerged condition, analysis of behavior of ultimate bearing capacity due to the effect of submergence, comparative study between theorem mechanisms and reliability analysis through Monte-Carlo simulation for various parameters of rock mass. The data generated from the mentioned aspects are represented in graphical form and histogram bar charts are developed from Monte Carlo simulation.
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Cerato, Amy B. "Scale effects of shallow foundation bearing capacity on granular material." 2005. https://scholarworks.umass.edu/dissertations/AAI3163655.
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This project investigated the scale effects of shallow foundation bearing capacity on granular materials to evaluate the observed decreasing trend of the bearing capacity factor, Nγ, with increasing footing width, B, for a given sand at a given density. Model and prototype scale square and circular footing tests ranging in size from 25.4 mm to 914.4 mm, were performed on two compacted sands at three relative densities. Results of model scale footing tests indicate that the bearing capacity factor, Nγ , is dependent on the absolute width of the footing for both square and circular footings. Direct shear box tests were performed in three different size shear boxes. Results of the direct shear tests indicate that there is a substantial scale effect; i.e., as the box size increases the friction angle, &phis;, decreases. The results of the direct shear box tests also show that the Mohr-Coulomb strength envelope is non-linear. The curvature shows higher strengths at low normal stresses and lower strengths at high normal stresses. High strengths at low confining stresses found in the direct shear box can help to explain the scale effect seen in small footings. Both the footing tests and direct shear tests were modeled using a lower and higher order Finite Element model. New Nγ values versus friction angle were generated using Drucker-Prager (1952) plane strain conditions. The values match the results of the footing tests from this study extremely well, while all other previously published solutions overpredict Nγ at high friction angles. The higher order model utilized the parameter, internal length, which has been shown to be a function of panicle shape, degree of interlocking and binder stiffness. The internal length parameter accurately predicted the direct shear, model and prototype footing test results. Although the scale effect of shallow foundation bearing capacity on granular materials still cannot be quantified, it can be predicted with the addition of the internal length parameter and the understanding that particle interlocking at low stresses significantly influences the results of the strength of a small scale footing and of a shear test.
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Chang, Jen-Chen, and 張振成. "The Ultimate Bearing Capacity of Shallow Foundation on Poorly Cemented Sandstone." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/wpjeyx.
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博士<br>國立交通大學<br>土木工程系所<br>96<br>The present paper aims to investigate the bearing behavior and failure mechanism of a shallow foundation of level ground and on/behind the crest of a poorly cemented sandstone slope. As a marginal geo-material, the load-bearing behavior of soft rock may not be closely modeled by the common theories. A clear understanding of the actual failure mechanisms of poorly cemented sandstone is crucial for estimating its bearing capacity. It is attempted to develop a bearing capacity theory for the geomaterial according to the observed failure mechanism from model tests in this study
Load-bearing model tests of strip footing on slope crest for slopes with various slope angles (0, 10, 20, and 30 degrees) and for footing at various setback distances (1 and 2.5 times of footing width) from 20° slope crest were conducted. The model rock slope was made of artificial rock that simulates natural poorly cemented sandstone. The comparison of various physical indices and mechanical properties supports that the mechanical properties of artificial soft rock are reasonablly close to the target natural soft rock. Based on a series of load-bearing model tests, it was found the ultimate bearing capacity decreases with the increase of the slope angle or the setback distance of footing. For slope angle greater than 30°, the influence of slope on the ultimate bearing capacity is more obvious. When the setback distance exceeds 2.5 times of the footing width or so, the ultimate bearing capacity is close to that of level ground.
Referred to the load-deformation curves, the load-bearing process can be divided into four stages; namely, the initial stress-adjusting stage, the linear stage, the non-linear stage, and finally, the ultimate stage. The active zone, in a shape of an inverted triangle, exists under the footing base. It is noted, as the slope angle increases and setback distance decreases, the shape of the inverted triangle deformed more toward the sloping side. In the active zone, the foundation material deformed downward and laterally toward to the sloping side. Hence, the vertical stress is the major principle stress . When the shear fractures composed of the passive zone finally reached the slope surface, the footing foundation would lose its bearing capacity eventually. The passive zone was formed by crack extended onto the slope surface. The passive zone was pushed laterally and outward. In the passive zone, is parallel to ground. A transition zone, which may contain one or two radial cracks, is located between the active and the passive zones. In the transition zone, the shear cracks provided stress discontinuities between the active zone and the passive zone; it enables the major principle plane rotate progressively from the active zone to the passive zone. The fracture models in two sides of footing were symmetrical only in the level-ground case which has the largest bearing capacity. Based on the observed behavior from the model tests, the failure mechanism may be modeled as a multi-block translation mechanism.
From the failure mechanism observed in the load-bearing model tests, it appears that common theories neither for soils nor for rigid rocks can fully model the bearing failure mechanism on poorly cemented sandstone. Unlike a plastic behavior in soil and brittle behavior in rigid rock, the failure mechanism for poorly cemented rock develops both plastic deformation and shear fractures in a progressive process.
Based on the experimentally observed failure mechanism, a simplified plastic collapse mechanism is proposed and an upper-bound solution based on a muti-block translation mechanism is formulated. Failure zones were divided into the active zone, the transitional zone, and the passive zone. In this study, it assumed that the transition zone contained three rigid triangle wedges with two velocity discontinuities. The angle of the rotation angle of the major principle stress from the active zone to the passive zone is affected by slope angle and setback distance. The upper-bound solution agrees well with the experimental bearing capacity for slope angle less than .
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Lin, Jing-Ying, and 林志盈. "Study of Ultimate Bearing Capacity of Shallow Foundation on Layered Soils." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/q3629w.
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碩士<br>義守大學<br>土木與生態工程學系<br>104<br>Ultimate bearing capacity and settlement analysis are two of the most important design items in the foundation design of structure. In homogenious sils, the theory for ultimate bearing capacity is very clear. But in the layered soils, the ultimate bearing capacity theory has not been to a definite conclusion. More research effort could be entered in this subject. In this research, the main objective is the ultimate bearing capacity of the layered soils. Finite element method will be adopted to obtain the ultimate bearing capacity for layered soils in several different cases.
The ultimate bearing capacity for single stiff clays and soft clays was respectively studied first. In the case of interlayer soils of stiff clays and soft clays, finite element method was adopted to obtain the relationship of foundation load and settlement and then the ultimate bearing capacity for layered clays. In this research, stiff clays and soft clays were with different stratum thickness, undrained shear strength and elastic modulus etc.. Therefore the ultimate bearing capacity for layered clays could be obtained in terms of ultimate bearing capacity of stiff clays and soft clays respectively. Therefore the complete understanding for ultimate bearing capacity of layered soils could be reached.
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Lai, Guo-Hao, and 賴國豪. "Laboratory Testing on Enhancing the Bearing Capacity of Shallow Foundation by Geotextile." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/60282588381756593172.
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碩士<br>朝陽科技大學<br>營建工程系<br>102<br>Reinforced soils have been used in the earth works for a long time. The strength of the soils are increased by the interaction between the geotextiles and soils. The geotextiles have long been used in earth retaining structures, but relatively little studies have been performed on reinforced shallow foundations.
This thesis extends the previous study performed by Shao-Yi Chung (2011) Laboratory tests were conducted to study the improvement of bearing capacity of shallow foundations reinforced by geotextile. The dimensions of the test cell are 90cm (L) × 90cm (W) × 100cm (H). A hydraulic loading system is used to apply the normal force to a (L) × 10cm (W) × 5cm (H) stripe footing. The unreinforced bearing capacity was obtained first and was compared with value calculated using Terzaghi’s equation. Various parameters such as: the burial depth of the reinforcement, the length of the reinforcement, the number of layers and the distance between layers were varied to investigate the improvement of bearing capacity.
Results of this study indicate that the optimum burial depth of the reinforcement is about 0.4 times the width strip footing, with a bearing capacity ratio(BCR) of about 1.67. The optimum reinforcement length is about 3 times the width of the strip footing with a BCR value of 1.81. Results of this study are in accord with previous numerical simulations performed by Shao-Yi Chung.
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Yi, Shao, and 鍾劭一. "Preliminary Study of Enhancing the Bearing Capacity of Shallow Foundation by Geotextile." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/54812582411963221149.
Full textAbstract:
碩士<br>朝陽科技大學<br>營建工程系碩士班<br>100<br>For weak soils, geotextiles are often used to composed a compound material to improve the engineering properties of soils. The geotextiles provide tensile resistance by interaction with soils thus improve their engineering properties. The geotextiles have long been used in earth retaining structures, but relatively little study have been performed on their use in reinforced shallow foundation.
In this study we simulated the reinforced shallow foundation and study the effects of different parameters on its bearing capacity by FLAC2D Finite Difference program. First, the bearing capacity of a unreinforced strip foundation was simulated and compared with the theoretical solution to verify the numerical model. The effects of different parameters, such as the depth of the reinforcement, the length of the geotextile, the number of layers and the distance between layers were also studied.
This research verifies that the reinforced shallow foundation can provide higher bearing capacity, especially for weak soils. Thus, should be a good alternative for ground improvement.
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Chung, Wen-Jen, and 鍾文仁. "Influence of neighboring footing on the foundation bearing capacity in numerical analysis." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/32793474030895129316.
Full textAbstract:
碩士<br>國立雲林科技大學<br>營建工程系碩士班<br>97<br>In recent years, the city expands rapidly.When we build the foundation, it will exist many buildings in the neighborhood.It often causes damage to neighboring buildings because of excavation. In order to avoid affect neighbor foundation, we study the influence of neighboring footing to bearing capacity in this thesis. Therefore, we change the width of footing, the depth of footing and the spacing of footing to observe the change of bearing capacity under the loading on the footing.
From these numerical results, when the ratio of footing spacing and width is between 0 and 1, the bearing capacity will increase obviously.When the depth of neighboring footing increases, the bearing capacity of existing footing will also decrease significant.When the width of both footings are 1 meter, it will reach to 10.77% decrement of bearing capacity.
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Yeh, Tsan-Yu, and 葉贊育. "Analytical Solution for Bearing Capacity in Transversely Foundation --- Use Slip Line Method." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/91560146023012100382.
Full textAbstract:
碩士<br>國立交通大學<br>土木工程研究所<br>81<br>It is very important for engineering safety to predict the
bearing capacity of foundation rock before engineering
strctures with large loads are built on the rock. Isotropic
solutions for the bearing capacity in foundation rocks cannot
be used for rocks that exhibit strength anisotropy. A few
analytical solutions for the bearing capacity in anisotropic
foundation rocks were proposed. These solutions are limited to
rock masses with strength anisotropy because of one set of weak
planes and bounded by a flat surface. For the bearing
capacities in aniostropic foundation rock on sloping ground or
on the crest of sloping ground, analytical solutions were not
considered for rocks with strength anisotropy in the
literature. In this thesis, new analytical solutions for the
bearing capacities and slip line in foundation rock with
strength anisotropy on flat surface and on the crest of sloping
ground are presented by slip line method. In the solutions, the
foundation rocks are modelled as plastic materials and satisfy
associate flow rules and modified Hoek-Brown failure critrion.
Numerical examples are conducted to investigate the effect of
the dip direction and angle of strata, the slope angle, and the
location of foundation at the crest of sloping ground on the
bearing capacity in the rocks with strength anisotropy.
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Strahler, Andrew W. "Bearing capacity and immediate settlement of shallow foundations on clay." Thesis, 2012. http://hdl.handle.net/1957/28739.
Full textAbstract:
Shallow foundations are extensively used to support structures of all
sizes and derive their support from near surface soils. Thus, they are typically
embedded up to a few meters into the soil profile. Designers of shallow
foundations are required to meet two limit states: overall failure of the soil
beneath the foundation (bearing capacity) and excessive settlement. Existing
bearing capacity design methods use an assumed shearing plane within the soil
and perfectly plastic soil behavior to estimate the ultimate resistance available.
The immediate settlement of a shallow foundation is typically approximated
using an elasticity-based method that does not account for actual, nonlinear
soil behavior. A load test database was developed from footing load tests
reported in the literature to assess the accuracy and uncertainty in existing
design methodologies for calculating bearing capacity and immediate
settlement. The assessment of uncertainty in bearing capacity and immediate
settlement was accomplished through the application of a hyperbolic bearing
pressure-displacement model, and the adaptation of the Duncan-Chang soil
constitutive model to footing displacements.
The prediction of bearing capacity using the general bearing capacity
formula was compared to the bearing capacity extrapolated from the load test
database using a hyperbolic bearing pressure-displacement model. On average
the general bearing capacity formula under-predicts the bearing capacity and
exhibits a significant amount of variability. The comparison was used to
develop resistance statistics that were implemented to produce resistance
factors for an LRFD based design approach using AASHTO load statistics.
The Duncan-Chang model was adapted to predict bearing pressure displacement
curves for footings in the load test database and used to estimate
governing soil parameters. Bearing pressure-displacement curves fitted to the
observed curves were used to back calculate soil stiffness. The soil stiffness
was used with an elasticity-based displacement prediction method to evaluate
the accuracy of the method. Finally, the back-calculated modulus from the
fitted Duncan-Chang model was used to assess the accuracy and uncertainty
associated with the elasticity-based K-factor, a correlation based stiffness
parameter. In general the comparisons indicate that the current design
procedures over-predict the bearing pressure associated with a given
displacement and exhibit a significant amount of uncertainty.<br>Graduation date: 2012
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CHENG, CHUN-YEN, and 鄭俊煙. "Upper bound limit analysis for the bearing capacity of shallow foundation on slope." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/29391553793382615666.
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