Dissertations / Theses: 'Embankment on soft soils'

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Manivannan, Ganeshalingam Aerospace Civil &amp Mechanical Engineering Australian Defence Force Academy UNSW. "Viscoplastic modelling of embankments on soft soils." Awarded by:University of New South Wales - Australian Defence Force Academy. School of Aerospace, Civil and Mechanical Engineering, 2005. http://handle.unsw.edu.au/1959.4/38743.

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A major instrumented geosynthetic reinforced approach embankment was constructed to 5.5 m elevation above ground, with prefabricated vertical drains, over a soft compressible clay deposit at Leneghan, Newcastle, Australia in May 1995. The field monitoring of settlements for over six years shows that the embankment manifests significant creep. The instrumentation, field performance and the finite element analyses for predicting the long-term performance of this embankment are described in this thesis. The maximum settlement of 1.1 m was observed one year after the completion of construction. However, the embankment continued to settle at a rate of 0.4 mm/day for the next 5 years. The horizontal displacements of 0.09-0.14 m at various locations and the maximum reinforcement strains of 0.67% were recorded. A numerical model was developed to perform a fully coupled large deformation elasto-viscoplastic finite element analysis for this performance prediction based on creep model proposed by Kutter and Sathialingam (1992). The foundation soil was modelled with creep material behaviour using six noded linear strain triangular elements. A well-documented case history ??? Sackville embankment, New Brunswick, Canada was analysed using this model as a benchmark problem and the model was found to predict all the behaviour characteristics reasonably well. The results obtained from finite element analysis using this model are shown to be in reasonable agreement with the observed performance of Leneghans embankment in terms of settlements, horizontal displacements, excess pore pressures and geosynthetic strains. But, the prediction of settlements was less than satisfactory beyond April 1999. Finite element analyses were performed to study the sensitivity of this embankment behaviour on the variation of hydraulic conductivity values and geosynthetic reinforcement properties. This sensitivity study indicated that the kv variation, the kh/kv ratio and the nominal values of geosynthetic properties adopted in the benchmark analysis are reasonable enough for the long-term behaviour prediction.

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Krenn, Harald. "Numerical modelling of embankments on soft soils." Thesis, University of Strathclyde, 2008. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21985.

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The design of embankments on soft soils requires a reliable estimate of deformations and stability of the embankment. Natural soft soils are structured materials, and as a consequence they exhibit anisotropy in their stress-strain-strength behaviour. The complex nature of soft soil makes it very difficult for designers to estimate deformations during construction and over time. The properties of very soft clays, silts and organic soils can be improved with deep mixing. Conventional design methods are very limited and do not account for the complex stress-strain-strength behaviour of the soft soil and/or the deep mixed soil. Numerical techniques, such as the finite element method provide a powerful tool, given the complex stress-strain-strength behaviour of the soft soil and/or the deep mixed material can be taken into account using advanced constitutive models. The aim of the thesis is to investigate through 2D and 3D numerical simulations using advanced constitutive models the behaviour of embankments constructed on soft clays. In addition to embankments constructed on natural soils, embankments on deep mixed columns are studied. Simulations investigate the effect of anisotropy, apparent interparticle bonding and destructuration on the predicted response. It was found that ignoring anisotropy and destructuration leads to underprediction of surface settlements and horizontal displacements. However, although the effect of anisotropy was more pronounced than the effect of destructuration, the latter is needed to represent the measured remoulded and natural undrained strength in time. Constitutive models with a hyperbolic stress-strain relationship give a good representation of the non-linear behaviour of deep mixed material. 3D simulations of embankments on deep mixed columns showed that with increasing column spacing, differential settlements occur between column and soil. The results furthermore demonstrate that floating columns can be very effective in settlement reduction.

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Schaefer, Vernon Ray. "Analysis of reinforced embankments and foundations overlying soft soils." Diss., Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/49886.

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The use of tensile reinforcement to increase the tensile strength and shear strength of soils has lead to many new applications of reinforced soil. The use of such reinforcing in embankments and foundations over weak soils is one of the most recent applications of this technology. The studies conducted were concerned with the development of and application of analytical techniques to reinforced soil foundations and embankments over weak soils. A finite element computer program was modified for application to reinforced soil structures, including consolidation behavior of the foundation soil. Plane strain and axisymmetric versions of the program were developed and a membrane element developed which has radial stiffness but no flexural stiffness. The applicability of the program was verified by comparing analytical results to case histories of reinforced embankments and to model studies of reinforced foundations. A simplified procedure for computing the bearing capacity of reinforced sand over weak clay was developed which is more general than those previously available. Good agreement with available experimental results was obtained, providing preliminary verification of the procedure. Extensive analyses were made of a reinforced embankment successfully constructed with no sign of distress, and of two reinforced embankments constructed to failure. These analyses showed that good agreement can be obtained between measured and calculated reinforcement forces, settlements, and pore pressures for both working and failure conditions. The analyses further show that the use of the finite element method and limit equilibrium analyses provide an effective approach for the design of reinforced embankments on weak foundations.
Ph. D.
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Zhao, Lin Shuang. "Modelling column-supported and geosynthetic-reinforced embankment on soft soil foundation." Thesis, University of Macau, 2018. http://umaclib3.umac.mo/record=b3951591.

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TEIXEIRA, CHRISTIANO FARIA. "SETTLEMENT ANALYSIS OF AN EMBANKMENT ON VERY SOFT SOIL IN BARRA DA TIJUCA." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2012. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=21333@1.

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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO
COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
PROGRAMA DE EXCELENCIA ACADEMICA
um depósito de solos muito moles da Barra da Tijuca (Baixada de Jacarepaguá), que pertence a uma planície costeira do Rio de Janeiro (RJ). O perfil de solos muito moles de fundação possuía até 17 m de espessura, caracterizados pelo Nspt igual a 0. O aterro foi construído em etapas e os recalques foram acelerados com a instalação de drenos verticais pré-fabricados na fundação. A construção do aterro durou cerca de 1,5 ano e foi monitorada por meio de instrumentação geotécnica. Campanhas de ensaios de campo e laboratório foram realizadas para determinação das características geotécnicas dos solos. Dez amostras foram coletadas em dois furos verticais de duas localidades virgens do depósito. Para evitar o amolgamento, cada etapa do processo de amostragem, desde a coleta até a moldagem dos corpos de prova, foi conduzida tomando-se cuidados especiais. Os corpos de prova foram moldados nas condições indeformada (horizontal e vertical) e completamente amolgada. Os procedimentos de moldagem dos corpos de prova foram associados à excelente qualidade da maioria dos corpos de prova moldados e por isso foram descritos detalhadamente. Todas as conclusões do trabalho levaram em consideração apenas os resultados dos ensaios realizados com corpos de prova considerados de excelente qualidade. Os ensaios de campo foram realizados em furos adjacentes aos furos onde foram coletadas as amostras indeformadas e na mesma região em que foram instalados grupos de instrumentos geotécnicos. A análise dos resultados dos ensaios de campo e laboratório e dos registros da instrumentação revela a existência de dois horizontes de solos muito moles que exibem características distintas e são separados por uma lente de areia contínua. O solo do horizonte superior (até 5 m de profundidade), que provavelmente foi formado após um período geológico de descarregamento do horizonte inferior, é caracterizado pelas condições de baixas tensões efetivas. O solo do horizonte inferior também está sob baixas tensões efetivas, contudo com uma tensão de préadensamento caracterizada pela diferença sp - sv0 25 kPa (constante com a profundidade), a qual pode ser associada ao mecanismo de carregamento e descarregamento mecânico. Uma correlação entre OCR (obtidas em ensaios de adensamento) e a razão Su/s’v0 (obtidas de ensaios de palheta e CPTu) foi atualizada para os solos do depósito. A alta compressibilidade dos solos foi confirmada pelos dados da instrumentação do aterro que mostraram recalques superficiais da ordem de 50 por cento da espessura do aterro (4,5 m). Os valores de Ca/Cc para os solos do depósito foram superiores aos valores característicos da maioria dos solos que se tem registro. Relações práticas para descrever a permeabilidade dos solos foram atualizadas. Os coeficientes de adensamento dos solos foram determinados por diversas formas e os resultados dos mesmos, apesar de apresentarem grande variabilidade (até dez vezes), não mostraram tendência quando os valores de campo (ensaios e dados de instrumentação) e laboratório foram comparados. O amolgamento dos corpos de prova afetou as características de permeabilidade e compressibilidade (primária e secundária) dos solos de ambos horizontes, mas os efeitos do mesmo foram mais severos nos solos do horizonte inferior. Uma previsão numérica, na qual se adotou um modelo para solo mole com fluência e foram considerados os parâmetros de laboratório, superestimaram levemente os recalques do aterro com o tempo.
This work presents a settlement analysis of an embankment built on a very soft soil deposit in Barra da Tijuca (Baixada de Jacarepaguá), which is located in Rio de Janeiro’s coast. The geotechnical profile shows a very soft soil with thickness reaching 17 m, with Nspt equal 0. The embankment was built in stages and its settlements were accelerated with prefabricated drains. The construction lasted about 1,5 year and was monitored by means geotechnical instrumentation. Field and laboratory test programs were carried out to define the geotechnical characteristics of the soil. Ten samples were collected from two vertical boreholes before any loading was applied to the soil. To avoid disturbance, each stage of sample process, from sampling to specimen preparation, was conducted with special procedures. Tests have been carried out both in undisturbed (vertical and horizontal directions) and completely disturbed conditions. The specimen preparation procedures are described in detail. Conclusions considered only the results of tests conducted on specimens with excellent quality. The in-situ tests were performed in vertical boreholes next to boreholes where the undisturbed samples were collected and in the same location in which geotechnical instruments group were installed. The analysis of the field and laboratory tests and instrumentation data revealed the existence of two very soft soil layers exhibiting distinct characteristics which are separated by a continuous sand lens. The upper soil layer (from surface down to about 5 m depth), that was probably formed after an unloading geological period of the underlying layer, is characterized by low effective in situ stresses. The underlying soil is also under low in-situ effective stresses, but with a preconsolidation pressure characterized by the difference s’p - s’v0 25 kPa (constant with depth). A correlation between OCR (from consolidation tests) and Su/sv0 ratio (from vane and CPTU tests) for similar soils has been updated. The high compressibility of soils was confirmed by the embankment instrumentation data. Ca/Cc values, higher than usual for most known soils, were found. Practical relationships have been updated to describe the permeability of the deposit. Soil consolidation coefficients were estimated in different ways and values, even though have showed large difference (up to ten times), did not showed tendency when laboratory or field (tests and instrumentation data) values were compared. Disturbance affected the permeability and compressibility (primary and secondary) characteristic of the soils of both layers, but its effects were more severe in the underlying layer. A numerical prediction, in which a creep-soft-soil model was used and parameters obtained from the laboratory tests were considered, lightly overestimated the embankment settlements with time.

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Bamunawita, Chamari. "Soft clay foundation improvement via prefabricated vertical drains and vacuum preloading." Access electronically, 2004. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20041013.160202/index.html.

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Ampuero, Milagros Victoria Fuertes. "Análise numérica e analítica de aterros reforçados sobre solos moles com uma camada superficial de areia." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/3/3145/tde-03072013-153310/.

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Os aterros reforçados sobre solo mole de resistência crescente com a profundidade, podem apresentar problemas durante o processo construtivo com respeito às rupturas e aos recalques inesperados. O presente trabalho visa avaliar o comportamento dos aterros reforçados a través de um estudo numérico, levando aos aterros até a ruptura sob condição não-drenada devido ao carregamento rápido, com o objetivo de estimar a influência da rigidez do reforço nas deformações, além disso, estudar o mecanismo da interação solo-reforço para um aterro reforçado. Foi utilizada a metodologia apresentada por Hinchberger & Rowe (2003), que leva em conta os recalques imediatos durante e após a construção. As análises numéricas de tensão-deformação foram realizadas pelo software PHASE 2, a calibração do programa foi feita com a literatura de aterros reforçados. Pretendeu-se mostrar a influência de uma camada superficial de areia sobre a argila mole na altura de ruptura e na deformação do reforço. Pelo método de elementos finitos foi definida uma metodologia para calcular as deformações do reforço para uma altura determinada e avaliar a estabilidade mediante o método de equilíbrio limite. Além disso, essa metodologia pode ser empregada para dimensionar o reforço requerido para um determinado fator de segurança.
Reinforced embankments on soft clayey soil where the strength increases with depth may present problems during construction process relative to failure and unexpected settlements. This study aims to evaluate the embankments behavior with a numerical study; the embankments were taken to failure in the undrained shear strength condition due to rapid upload to study the effect of reinforcement tensile stiffness on the reinforcement strains. Besides, it aimed to study the mechanism of soil-reinforcement interaction for a reinforced embankment. The method of Hinchberger & Rowe (2003) was used, which considers the displacements before and post construction. The numeric analysis of stress-strain was performed by the software PHASE 2; the calibration of the software was made according to published reinforced embankment literature. The study intends to show the influence of a sand layer above the clayey soil, on the failure height and reinforcement strains. Based on finite elements methods, a methodology was defined to estimate the reinforcement strains for a required design height and to study the stability by performing limit equilibrium analysis. Furthermore, this methodology could be used to specify the required reinforcement stiffness for a specific factor of safety.

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Pickles, A. R. "The application of critical state soil mechanics to predict ground deformations below an embankment constructed on soft alluvium." Thesis, City University London, 1989. http://openaccess.city.ac.uk/7404/.

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An embankment has been constructed to a maximum height of approximately twelve metres at Beckton, east London. The embankment is underlain by up to eight metres of alluvium and made ground. The embankment was monitored during construction. Centreline settlements of the order of O.6m and horizontal movements at the embankment toe of up to O.1Sm were measured. The excess pore pressures generated during construction were found to dissipate rapidly. Soil samples recovered from the site have been tested at city University. The alluvial clay is shown to have extremely variable compression characteristics and it is not possible to determine a single set of critical state soil parameters from the "undisturbed" soil samples. The use in design of parameters derived from reconstituted soil samples is investigated. Laboratory test results indicate that a small quantity'of organic matter in the soil has a large effect on the engineering properties of the alluvial clay. The importance of not dry~ng soils which contain organic matter is highlighted. It is shown that, despite the effects of the organic matter, critical state concepts and in particular the modified Cam clay soil model can be used to predict the behaviour of the alluvial clay in a wide variety of laboratory tests. standard methods of determining the yield stress or preconsolidation pressure are shown to be inadequate when used to analyse the results of compression tests performed at a constant rate of loading. An alternative method, the Lambda construction, is proposed and this is shown to be both reliable and objective. Two distinct testing methods have been used to probe the state boundary surface of the reconstituted alluvial clay samples. The results of these tests appear to indicate the existence of a single state boundary surface for both Ko and isotropically compressed samples. This surface has a shape similar to that predicted by the modified Cam clay soil model. This result conflicts with the findings of many other investigators. Finite element modelling of the embankment construction has been carried out. A single set of soil parameters derived from tests on the reconstituted clay were used to represent the alluvial stratum. The construction of the embankment was modelled as a drained event. The results are shown to compare favourably with the actual field data.

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Widodo, Slamet. "Analysis of dynamic loading behaviour for pavement on soft soil." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2014. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-129531.

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The increasing need for regional development has led engineers to find safe ways to construct the infrastructure of transportation on soft soils. Soft soil is not able to sustain external loads without having large deformations. The geotechnical properties of soft soil which is known for its low bearing capacity, high water content, high compressibility and long term settlement as well. In pavement engineering, either highway or runway as an infrastructure, a pavement encompasses three important parts namely traffic load, pavement and subgrade. Traffic load generated from tire pressure of vehicle and/or airplane wheels are usually around 550 kPa even more on the surface of the pavement. Pavement generally comprises granular materials with unbounded or bounded materials located between traffic load and subgrade, distributing the load to surface of subgrade. One of the promising soil improvement techniques is a piled embankment. When geosynthetics layer is unrolled over piles, it is known as geosynthetics supported piled embankment. Particularly in deep soft soil, when piles do not reach a hard stratum due to large thickness of the soft soil, the construction is an embankment on floating piles. Furthermore, because of different stiffness between piles and subsoil, soil arching effect would be developed there. By using Finite Element analysis, some findings resulted from experimental works and several field tests around the world as field case studies are verified. Some important findings are as follows: the stress concentration ratio is not a single value, but it would be changed depending on the height of embankment, consolidation process of subsoil, surcharge of traffic load, and tensile modulus of geosynthetics as well. Ratio height of embankment to clear piles spacing (h/s) around 1.4 can be used as a critical value to distinguish between low embankment and high embankment. When geosynthetics is applied to reinforce a pavement/embankment, the vertical distance of geosynthetics layers and number of geosynthetics layers depend on the quality of pavement material. The lower layer of geosynthetics withstands a tensile stress higher than upper layer. Primary reinforcements for geosynthetics in piled embankments are located at span between piles with maximum strains at zones of adjacent piles. Traffic load that passes through on the surface of the pavement can reduce the soil arching, but it can be restored during the off peak hours. Settlements of embankments on floating piles can accurately be modelled using the consolidation calculation type, whereas the end-bearing piles may be used the plastic calculation type. Longer piles can be effectively applied to reduce a creep. By applying length of floating piles more than 20% of soft soil depth, it would have a significant impact to reduce a creep on a deep soft soil.

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Antunes, Caroline Sidrim Gomes Leite Mansur. "Comportamento dos aterros que compõem a obra do Arco Metropolitano do Rio de Janeiro." Universidade do Estado do Rio de Janeiro, 2012. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=5528.

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O presente trabalho tem como objetivo a análise do comportamento dos aterros instrumentados que compõem a obra do Arco Metropolitano do Rio de Janeiro. Os resultados da instrumentação de campo serão discutidos e retroanalisados, juntamente com dados disponíveis na literatura, buscando-se a definição de parâmetros confiáveis, representativos do comportamento da argila compressível da região em estudo. O Arco Metropolitano do Rio de Janeiro é uma rodovia projetada que servirá como ligação entre as 5 principais rodovias que cortam o município do Rio de Janeiro. Dada a magnitude da obra e a ocorrência de significativas espessuras de solos moles em alguns trechos da região, determinados aterros que compõem a rodovia foram instrumentados com placas de recalque e inclinômetros, instalados em diferentes estações de monitoramento, no intuito de avaliar os deslocamentos verticais e horizontais dos aterros durante o processo construtivo. De posse de parâmetros confiáveis, procede-se à simulação numérica do processo construtivo de um dos aterros, a partir do programa PLAXIS, de elementos finitos. Os resultados numéricos são confrontados com a instrumentação de campo (fornecida por placas de recalque) e com os resultados de previsões teóricas (teoria de adensamento unidimensional). Em projetos de aterros sobre solos compressíveis, a instrumentação geotécnica é de grande importância, pois permite acompanhar o desenvolvimento de todo o processo construtivo, e as deformações decorrentes da sobrecarga imposta pelo lançamento de camadas de aterro. A imposição de um carregamento sobre solos de alta compressibilidade e baixa resistência pode acarretar em grandes deformações ao longo do tempo, além de rupturas indesejáveis do solo de fundação. Os resultados comprovaram que a modelagem numérica mostrou-se uma ferramenta adequada para a previsão dos recalques totais e tempos de adensamento. A definição de parâmetros representativos, com base em ensaios executados em amostras de boa qualidade, é o primeiro passo para a previsão coerente da evolução dos recalques com o tempo. A retroanálise do comportamento de aterros sobre solos moles permite a reavaliação das premissas de projeto, uma vez que as limitações das teorias de análise e a dificuldade na seleção de parâmetros, muitas vezes acarretam em estimativas de recalque incoerentes com as observações de campo.
The present work aims to analyze instrumented embankments behavior that composes the Rio de Janeiros Arco Metropolitano construction. Field instruments results will be discussed and reanalyzed, altogether with data available in literature, seeking to define reliable parameters, representative of the compressible clay behavior into the studied area. The Rio de Janeiros Arco Metropolitano is a road designed to work as a link between the five major highways that cross Rio de Janeiro city. Given to the works magnitude and the occurrence of significant thickness of soft soil in some parts of the region, some landfills that form the highway were instrumented with inclinometers and settlement plates installed in different monitoring stations in order to evaluate the vertical and horizontal landfill during the construction process. Armed with reliable parameters, it will be carried out to the numerical simulation of the construction process of a landfill, from the program PLAXIS, of finite elements. The numerical results will be compared with field instrumentation (provided by boards of repression) and the results of theoretical predictions (one-dimensional consolidation theory). In projects of embankments on compressible soil, geotechnical instrumentation is very important because it allows following the development of the entire construction process and the deformations due to overload imposed by the release of embankment layers. The imposition of a load on soils high compressibility and low resistance can lead to large deformations over time and undesirable disruptions in foundation soil. Concerning the numerical modeling, results proved to be a suitable tool to total settlements and times of consolidation prediction. The representative parameters definition, based on tests performed on good quality samples, is the first step for predicting the development of coherent repression with time. The reanalysis of the embankments behavior on soft soil permits the revaluation of the premises of the project, since the theory limitations of analysis and the difficulty in selecting parameters often leads to inconsistent estimates of repression with field observations.

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Blanco, Edwin Fernando Ruiz. "Geosynthetic-reinforced embankments on soft soils : numerical analysis of the strain mobilization in the reinforcement at failure, service condition and staged construction." Instituto Tecnológico de Aeronáutica, 2013. http://www.bd.bibl.ita.br/tde_busca/arquivo.php?codArquivo=2780.

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In this dissertation, the behavior of geosynthetic reinforced embankments constructed on soft cohesive foundations under undrained and partially drained conditions is examined by conducting a rigorous numerical analysis using the finite element method for some particular case studies. Special attention is given to the mobilized strains in the geosynthetic reinforcement at embankment failure, short and long-term working conditions state and during staged construction considering the influence of the time-dependency of the system in terms of construction rate, excess pore pressure dissipation and viscous deformations in the soil foundation (i.e., creep). The effects of reinforcement stiffness and adopted constitutive model are also investigated. The obtained results highlight the importance of assessing the allowable compatible reinforcement strain at failure and taking into account this soil-reinforcement interaction. It is illustrated the significant combined influence of consolidation process and soft soil creep deformation on the numerically observed embankment performance at working conditions, particularly in terms of mobilized reinforcements strains. Finally, an approximate approach for studying numerically staged constructed embankments is presented, pointing out the adequate definitions of Limit States for the considered stages and the effects of time in the embankment behavior.

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Alves, Nelson Santos de Oliveira. "Estudo do comportamento de aterros reforçados sobre solos moles com utilização de drenos verticais pré-fabricados." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/3/3145/tde-03112014-153454/.

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Neste trabalho apresentou-se a simulação numérica de aterros reforçado sobre argila mole com uso de drenos verticais pré-fabricados. O objetivo foi analisar o comportamento de um aterro reforçado com geossintético aliado ao uso de drenos verticais pré-fabricados. As análises numéricas de tensão-deformação foram realizadas pelo software PLAXIS 8.2. 2D. Pretendeu-se analisar as influências da rigidez do reforço, espaçamento entre drenos, velocidade de construção, construção do aterro em etapas, no comportamento dos aterros, como recalques verticais, deformações laterais e deformação do reforço. Foi utilizada a metodologia apresentada por Li & Rowe (2001), para a validação da modelagem dos aterros. A calibração do programa foi feita com a literatura de aterros reforçados. Nos resultados apresentados foram verificadas vantagens, como por exemplo: aceleração dos recalques e possibilidade da construção de aterros mais altos. O MEF mostrou que pode ser útil na escolha do reforço mais adequado para a condição de obra desejada, juntamente com espaçamento entre drenos. Foi possível verificar que a combinação de ambos os elementos pode ser bastante vantajosa em relação à utilização de apenas um deles. As deformações do reforço determinadas pelo MEF podem ser usadas para escolher o reforço adequado para um aterro sobre solo mole. Através dos resultados do método de elementos finitos pretendeu-se definir uma metodologia para calcular as deformações do reforço para uma altura de aterro determinada.
This paper presents the numerical simulation of reinforced embankment on soft clay with the use of prefabricated vertical drains. The objective is to analyze the behavior of a geosynthetic reinforced embankment along with the use of prefabricated vertical drains. The numerical analyzes of the stress-strain were performed by software PLAXIS 8.2. 2D. It was intended to analyze the influence of the stiffness of the reinforcement spacing between drains, construction speed, construction of the embankment in stages, the behavior of the landfill as settlements vertical, lateral deformations and deformation strengthening. We used the method presented by Li & Rowe (2001), to validate the modeling of landfills. The calibration was performed with the program literature reinforced embankments. In the following results were observed advantages such as: speeding up the possibility of repression and construction of embankments higher. MEF showed that may be helpful in selecting the most suitable for enhancing the desired work condition, with the spacing between drains. It can be seen that the combination of both elements can be quite advantageous over the use of just one. The deformation of the reinforcement determined by MEF can be used to choose the proper reinforcement for an embankment on soft soil. Through the results of the finite element method was intended to define a methodology to calculate the deformations of the reinforcement to a height of embankment determined.

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Araújo, Danielle Batista Dias de. "Análise das deformações dos aterros que compõem a obra do Arco Metropolitano do Rio de Janeiro." Universidade do Estado do Rio de Janeiro, 2015. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=9297.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
O presente trabalho tem como objetivo a análise numérica do comportamento dos aterros instrumentados que compõem a obra do Arco Metropolitano do Rio de Janeiro. Os resultados da instrumentação de campo serão retroanalisados, juntamente com dados disponíveis na literatura, buscando-se a definição de parâmetros confiáveis, representativos do comportamento da argila compressível da região em estudo. O Arco Metropolitano do Rio de Janeiro é uma rodovia projetada que servirá como ligação entre as principais rodovias que cortam o município do Rio de Janeiro. Devido a presença de grandes espessuras de solo compressível em alguns trechos da região, cortados pelo traçado da rodovia, instrumentos de monitoramento, como placas de recalque e inclinômetros, foram utilizados para avaliar os deslocamentos verticais e horizontais dos aterros durante o processo construtivo. Para este trabalho foram selecionados trechos de aterros representativos, devido à magnitude dos recalques, qualidade do resultado da instrumentação e diferentes métodos construtivos. A partir da análise dos parâmetros de projeto e dos parâmetros encontrados na literatura, procede-se à simulação numérica do processo construtivo dos aterros selecionados com o programa PLAXIS, de elementos finitos, através de modelagem bidimensional. Os resultados numéricos são confrontados com a instrumentação de campo (placas de recalque e inclinômetros) e com os resultados de previsões teóricas (teoria de adensamento unidimensional). Os resultados comprovaram que a modelagem numérica mostrou-se uma ferramenta adequada para a previsão dos recalques totais, tempos de adensamento e ganho de resistência ao longo do tempo. A retroanálise do comportamento de aterros sobre solos moles permite a reavaliação das premissas de projeto, uma vez que as limitações das teorias de análise e a dificuldade na seleção de parâmetros, muitas vezes acarretam em estimativas de recalque incoerentes com as observações de campo.
This study aims to numerical analysis of the behavior of instrumented embankments that compose the the Arco Metropolitano from Rio de Janeiro. The field instrumentation results will be retroanalysed, together with data available in the literature, seeking the definition of reliable parameters, representative of the behavior of compressible clay in the area of study. The Arco Metropolitano of Rio de Janeiro is a highway designed to link the main highways that cross the city of Rio de Janeiro. Due to the presence of large compressible soil thickness in some parts of the region, cut by the route of the highway, monitoring instruments, such as settlement plates and inclinometers, were used to evaluate the vertical and horizontal displacements of the landfill during the construction process. Representative landfills stretches were selected for this study due to the magnitude of settlements, quality of the result of instrumentation and different construction methods. By the analysis of the parameters from this project and the parameters found in the literature, it proceeds to the numerical simulation of the construction process of landfills selected with the PLAXIS software, of finite elements, through two-dimensional modeling. The numerical results are compared with field instrumentation (provided by settlement plates and inclinometer) and the results of theoretical predictions (one-dimensional consolidation theory). Results showed that the numerical modeling proved to be a suitable tool for the prediction of total settlements, thickening times and gaining strength over time. The back analysis of soft soils on landfill behavior allows the reassessment of project assumptions, once the limitations of the analysis of theories and the difficulty in the selection of parameters often results in estimates of repression inconsistent with the field observations.

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14

Ellis, Edward Alan. "Soil-structure interaction for full-height piled bridge abutments constructed on soft clay." Thesis, University of Cambridge, 1998. https://www.repository.cam.ac.uk/handle/1810/283725.

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15

Walker, Rohan. "Analytical solutions for modeling soft soil consolidation by vertical drains." Access electronically, 2006. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20060725.102120/index.html.

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16

Navin, Michael Patrick. "Stability of Embankments Founded on Soft Soil Improved with Deep-Mixing-Method Columns." Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/28654.

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Foundations constructed by the deep mixing method have been used to successfully support embankments, structures, and excavations in Japan, Scandinavia, the U.S., and other countries. The current state of practice is that design is based on deterministic analyses of settlement and stability, even though deep mixed materials are highly variable. Conservative deterministic design procedures have evolved to limit failures. Disadvantages of this approach include (1) designs with an unknown degree of conservatism and (2) contract administration problems resulting from unrealistic specifications for deep mixed materials. This dissertation describes research conducted to develop reliability-based design procedures for foundations constructed using the deep mixing method. The emphasis of the research and the included examples are for embankment support applications, but the principles are applicable to foundations constructed for other purposes. Reliability analyses for foundations created by the deep mixing method are described and illustrated using an example embankment. The deterministic stability analyses for the example embankment were performed using two methods: limit equilibrium analyses and numerical stress-strain analyses. An important finding from the research is that both numerical analyses and reliability analyses are needed to properly design embankments supported on deep mixed columns. Numerical analyses are necessary to address failure modes, such as column bending and tilting, that are not addressed by limit equilibrium analyses, which only cover composite shearing. Reliability analyses are necessary to address the impacts of variability of the deep mixed materials and other system components. Reliability analyses also provide a rational basis for establishing statistical specifications for deep mixed materials. Such specifications will simplify administration of construction contracts and reduce claims while still providing assurance that the design intent is satisfied. It is recommended that reliability-based design and statistically-based specifications be implemented in practice now.
Ph. D.

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17

Holko, Jeffrey M. "Shear Strength Correlations for Ohio Highway Embankment Soils." Ohio University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1205248711.

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18

Havel, Frantisek. "Creep in soft Soils." Doctoral thesis, Norwegian University of Science and Technology, Faculty of Engineering Science and Technology, 2004. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-297.

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As more and more constructions are concentrated in densely populated urban areas, there is an increasing need to construct buildings and geotechnical structures on soft clay materials, which usually produce significant creep deformation. Although a lot of research work has been related to the creep behaviour of a natural clay material, there are still many questions about this phenomenon. Even today, prediction of the time dependent deformation is generally very problematic. Detailed laboratory, in-situ and numerical studies of soft soil creep are necessary for the better understanding and consequently, better prognosis of this behaviour. All these studies were performed and will be presented in this thesis.

The long-term, one-dimensional consolidation has been investigated by oedometer tests on undisturbed Norwegian Kvenild quick clay, undisturbed Norwegian Glava clay, undisturbed and remolded Norwegian Onsøy clay and undisturbed Czech Terlicko clayey shale. All tests have been performed in an incremental loading oedometer apparatus with a lever arm, where, in the case of the Glava clay and the Terlicko clayey shale, two sizes of oedometer rings have been used. Detailed means of evaluating the stress-strain-time oedometer behaviour using a time resistance concept introduced by Professor Nilmar Janbu [46,48] is described. The application of the Soft-soil-creep model is presented. This is implemented in the geotechnical finite element program PLAXIS 8.1, for the mathematical modelling of the longterm oedometer test, with emphasis on the correct choice of the input parameters based on the oedometer test results, and their influence to the model’s behaviour.

The undrained and drained deviatoric creep behaviour of the Norwegian Glava clay and the Czech Terlicko clayey shale have been studied under triaxial compression. Two different triaxial apparatuses have been used in the study - standard triaxial apparatus made by Wille Geotechnik Gmbh and unique Creep Triaxial apparatus made at NTNU. A large number of undrained and drained deviatoric creep tests under different conditions have been carried out on 100x50 mm (1:2) and 50x50 mm (1:1) cylindrical specimens. Evaluation of the deviatoric creep behaviour based on the time resistance concept together with detailed description of tests conditions is reported. Data is presented showing the relation between stress level, i.e. degree of shear mobilisation at the start of the creep, time, pore pressure development and accumulated axial creep strain. Significant effort has been put into the study of the undrained triaxial tests on 1:1 clay specimens in general and undrained deviatoric creep triaxial tests on 1:1 clay specimens in particular. The problem connected with the pore pressure development and measurement is presented. A 2D numerical study of the undrained triaxial deviatoric creep tests has been done on 1:1 and 1:2 specimens using the finite element program PLAXIS 8.1. There is also a comparison of the laboratory and numerical behaviour.

Study of the viscosity and creep behaviour of a natural clay has been performed with modular compact rheometer. The MCR 300 rheometer has been used for the rheological investigation of the Norwegian Glava clay. Oscillatory, rotational and creep tests have been done with this apparatus. The basic characterisation of these tests is presented together with their evaluation. Deviatoric creep tests on modular compact rheometer have been evaluated based on the time resistance concept and compared with deviatoric creep tests on a standard triaxial apparatus. The analysis of the Czech Terlicko dam with emphasis on the creep behaviour has been performed based on the cooperation with the Povodi Odry, a.s., Czech Republic. A detailed investigation of the undisturbed clayey shale from the Terlicko dam substratum has been done in the geotechnical and geological laboratory. The characterisation of Terlicko clayey shale is reported base on the laboratory tests results. The in-situ behaviour of the Terlicko dam with emphasis to the uplift of the righthand slope hillside is described. In order to understand the in-situ behaviour a numerical study of the Terlicko dam has been done with PLAXIS 8.1 and Soft-soilcreep model. Results from this 2D numerical test together with recommendations and suggestions are presented.

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19

Ma, Evan Sau Yue. "Finite element analysis of embankment on soft Indian River clay." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/99623.

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Thesis: M. Eng., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2015.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 102-103).
This thesis re-analyzed the performance of an approach embankment for a new bridge across the Indian River Inlet in Delaware. The 115 ft. wide mechanically stabilized earth embankment (up to 45 feet above ground level) was founded on a 60 ft. deep layer of soft clay. Consolidation of the soft, normally consolidated clay was accelerated through installation of an array of prefabricated vertical drains. The performance was monitored during staged construction and for a period of 1.25 years after construction (2006-2008). During this, the embankment settled up to 6.5 feet, while large lateral spreading in the clay was restrained by overlying sand layers. The side walls tilted by up to 1.1°. The measured ground movement far exceeded the expectations of the designers and the embankment was eventually dismantled in 2008. The current research evaluates site conditions from field investigations carried out in 2003 and 2007 which included a program of 1 -D consolidation and triaxial laboratory shear testing on clay samples. Plane strain numerical analyses were carried out using PLAXIS 2D AETM using the Modified Cam-Clay and MIT-E3 effective stress models to represent clay behaviour. The numerical predictions are generally in very consistent agreement with measured settlements below the embankment and with lateral deflections measured by inclinometers. The analyses show significant lateral deformations arise due to asymmetry in the loading particularly during the staged construction of the embankment. The current results suggest that the measured performance could be credibly predicted using available site investigation and laboratory test data.
by Evan Sau Yue Ma.
M. Eng.

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20

Rujikiatkamjorn, Cholachat. "Analytical and numerical modelling of soft clay foundation improvement via prefabricated vertical drains and vacuum preloading /." Access electronically, 2005. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20060523.123914/index.html.

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21

Kwok, C. M. "Finite element studies of reinforced embankments on soft ground." Thesis, University of Sheffield, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382420.

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22

Sam, Wa Ngai. "Numerical modeling of embankment on soft marine clay stabilized by vertical drains." Thesis, University of Macau, 2003. http://umaclib3.umac.mo/record=b1445106.

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23

Mwasha, Abrahams Patton. "Limited life basal reinforcement for an embankment built on saturated soft clay." Thesis, University of Wolverhampton, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.420219.

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24

FORMIGHERI, LUIS EDUARDO. "BEHAVIOR OF AN EMBANKMENT ON A SOFT CLAY DEPOSIT AT BAIXADA FLUMINENSE." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2003. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=4261@1.

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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
O comportamento de um aterro sobre argila mole da Baixada Fluminense foi estudado. Este aterro foi executado para a implantação da Indústria Rio Polímeros, com 3 metros de espessura, assente sobre um colchão drenante. Antes da construção, a área foi coberta com uma manta de geotêxtil. Para acelerar os recalques do aterro, geodrenos foram instalados na argila mole. O aterro foi instrumentado com inclinômetros, placas de recalque e piezômetros. Durante a construção, foram observadas rupturas em áreas localizadas do aterro. Ensaios de palheta e piezocone foram realizados em diferentes etapas da obra. A resistência não drenada (Su) nos ensaios de palheta apresentaram-se dentro dos valores reportados em trabalhos anteriores. Nos ensaios de piezocone, Su apresentou um decréscimo com a profundidade. Os valores de OCR, estimados com o piezocone, situaram-se entre 1,5 e 3,0. O comportamento do aterro foi avaliado quanto a recalques e estabilidade. O método de Asaoka permitiu uma estimativa satisfatória do coeficiente de adensamento e dos recalques. Os recalques estimados pela teoria de Terzaghi foram cerca de 2,5 vezes maiores do que os registrados no campo, devido a incertezas na compressibilidade da argila mole. O método de Asaoka indicou, para drenagem puramente vertical, um valor de cv cerca de 100 vezes maior que os valores de ensaios de laboratório e 2 vezes menor que os valores estimados para drenagem combinada e para ensaios de piezocone. A estabilidade do aterro foi avaliada em análises por equilíbrio limite. Os resultados confirmaram a existência de uma potencial instabilidade em algumas regiões do aterro.
The behavior of an embankment on a soft clay deposit at Baixada Fluminense was studied. This embankment was constructed for implantation of Rio Polimeros Industry. The embankment layer is 3m thick and is placed over a layer of granular material. Before construction the entire area was covered with a geotextil. Geodrains were also installed to accelerate clay layer settlements. Some localized embankment failures were observed during construction. Vane and CPTU tests were performed at different construction stages. Values of undrained strength (Su), provided by vane tests, are in agreement with results reported in literature, for soft clay deposits at Baixada Fluminense. On the other hand, CPTU tests indicated a Su profile decreasing with depth. OCR values were estimated between 1.5 and 3.0. The performance of the embankment construction was evaluated with respect to its stability and settlement. The Asaoka`s method allowed a suitable evaluation of both coefficient of consolidation and final settlements. However, settlements computed by Terzaghi`s theory were about 2.5 times greater than monitored field values. These differences were attributed to uncertainties related to the clay layer compressibility parameters. The vertical coefficient of consolidation, computed with Asaoka`s method, was 100 times greater than laboratory results and 2 times smaller than values estimated for combined consolidation and by CPTU data. The embankment stability was evaluated with limit equilibrium analyses. The results confirmed the occurrence of instability conditions at localized embankment areas.

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25

Li, Maoxin. "Seepage induced instability in widely graded soils." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/862.

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Internal instability of a widely graded cohesionless soil refers to a phenomenon in which its finer particles migrate within the void network of its coarser particles, as a result of seepage flow. Onset of internal instability of a soil is governed by a combination of geometric and hydromechanical constraints. Much concern exists for embankment dams and levees built using soils with a potential for internal instability. Migration of finer particles to a boundary where they can exit, by washing out, may cause erosion or piping failure and, occasionally, induce collapse of these soil structures. There is a need, in professional practice, to better understand the phenomenon and to develop improved methods to evaluate the susceptibility of a soil. A series of permeameter tests was performed on six widely-graded cohesionless materials. The objectives are to assess the geometric indices proposed for evaluation of susceptibility, and examine hydromechanical factors influence the onset of internal instability. A modified slurry mixing technique, with discrete deposition, was found satisfactory for reconstitution of the homogeneous saturated test specimens. The onset of internal instability was founded to be triggered by a combination of effective stress and hydraulic gradient. The finding yields a hydromechanical envelope, unique for a particular gradation shape, at which internal instability initiated. Three commonly used geometric criteria were comprehensively evaluated with reference to these experimental data and also a database compiled from the literature. The relative conservatism of each criterion was examined and a modified semi-empirical geometric rule then proposed based on the capillary tube model. A theoretical framework for plotting the hydromechanical envelope was established based on an extension of the α concept of Skempton and Brogan, and subsequently verified by test data. Finally, a novel unified approach was proposed to assess the onset of internal instability, based on combining geometric and hydromechanical indices of a soil.

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26

Chung, Shin Fun. "Characterisation of soft soils for deep water developments." University of Western Australia. School of Civil and Resource Engineering, 2005. http://theses.library.uwa.edu.au/adt-WU2005.0079.

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[Truncated abstract] This research has studied the penetration and extraction resistance profiles of different types of penetrometers in soft clay. The penetrometers of interest include the cone, T–bar, ball and plate. Effects of the surface roughness and aspect ratio of the T–bar penetrometer on its resistance have also been investigated. Undrained shear strength, Su, profiles derived from the penetration tests are compared with the shear strengths measured from field vane shear tests and laboratory (triaxial and simple shear) tests. Both in situ and centrifuge model penetration tests were undertaken for the research. In addition, ‘undisturbed’? tube samples were retrieved from both the field and the centrifuge strongbox samples (after completion of the centrifuge tests) for laboratory testing. The in situ testing was carried out in Western Australia, at the Burswood site near Perth, with tests including cone, T–bar, ball and plate penetrometer tests, and vane shear tests. Interestingly, the T–bar, ball and plate (‘full-flow’) penetrometers showed a narrow band of resistance profiles both during penetration and extraction, with a range of around 15 % between the highest and lowest profiles and standard deviation of 15 %. However, the cone penetrometer gave similar resistance at shallow depths but increasingly higher penetration resistance at depths greater than 7 m – a phenomenon that is also common in offshore results. During extraction, the cone penetrometer gave a higher resistance profile than the full–flow penetrometers for much of the depth of interest. The Su profile measured directly from the vane shear tests falls within the Su profiles derived from the penetration resistances of the full–flow penetrometers, using a single bearing factor, N = 10.5 (the value originally suggested in the literature for a T–bar penetration test). Again, the cone penetrometer demonstrated diverging results, requiring two separate values for the cone factor, Nkt (10.5 initially increasing to 13 for depths below 10 m) in order to give Su similar to the vane shear tests. This highlights the possible variability of the cone factor with depth. Cyclic penetration and extraction tests were performed at specific depths for each fullflow penetrometer. These tests comprised displacement cycles of ±0.5 m about the relevant depth, recording the penetration and extraction resistances over five full cycles. The results may be used to derive the remoulded strength and sensitivity of the soil. Laboratory tests such as triaxial and simple shear tests were performed on ‘undisturbed’ tube samples retrieved from the same site to evaluate the in situ shear strengths in the laboratory. However, the resulting Su data were rather scattered, much of which may be attributed to variable sample quality due to the presence of frequent shell fragments and occasional silt lenses within the test samples. In general, N factors for the full–low penetrometers, back–calculated using Su values measured from the simple shear tests, fell mainly in a range between 9.7 and 12.8 (between 10.4 and 12.2 for the standard size T–bar (250 mm x 40 mm))

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AZEVEDO, FERNANDO DUARTE. "SETTLEMENTS OF THE SOFT SOILS DEPOSIT CAMBOINHAS, RJ." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2015. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=25351@1.

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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
O acompanhamento dos recalques de aterros, por meio de nivelamento topográfico periódico, permite estimar a evolução dos mesmos, bem como retroanalisar os parâmetros adotados em determinado projeto. Neste trabalho, recalques foram medidos em um aterro experimental sobre um depósito com 12 m de espessura de solos moles em Camboinhas, Niteroi (RJ), construído entre o final de 1977 e o início de 1978. O aterro serviu como modelo em escala real para a realização de estudos geotécnicos diversos na PUC-Rio, auxiliando o projeto de um empreendimento imobiliário da época. A obra foi embargada pouco tempo após seu início e, desde então, nenhum empreendimento foi realizado. Em 2013, novas amostras Shelby foram extraídas, para a realização dos ensaios de laboratório desta pesquisa. Ensaios de campo também foram realizados. Verificou-se que os recalques causados pela construção do aterro ainda estão ocorrendo, 37 anos após sua execução. Compararam-se, também, os valores de OCR de laboratório com os obtidos por meio de correlações empíricas com os resultados de campo. Por fim, foram feitas previsões da evolução do recalque médio com o tempo e da magnitude do valor total médio.
Monitoring of embankment settlements using periodic topographic leveling allows one to preview their evolution, and to assess the parameters used in a specific design. In this research, settlements of an experimental embankment constructed between the end of 1977 and the beginning of 1978, over a 12 m thick soft soils deposit in Camboinhas, Niteroi (RJ), were monitored. At that time, the embankment served as large model to help designing of a commercial housing development. The work was hampered shortly after the end of embankment s construction and, since then, no enterprise was held. In 2013, in this research, new Shelby samples were obtained in order to carry out series of laboratory tests. Settlements due to the embankment construction were noted to be still progressing. Also, OCR values from laboratory tests were compared to those empirically evaluated from field results. Finally, the magnitude of total settlement and its progress with time were estimated.

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28

Palmer, Andrew L. "Load Transfer Mechanisms for Piles in Soft Soils." DigitalCommons@USU, 1994. https://digitalcommons.usu.edu/etd/4603.

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The purpose of this thesis is to interpret pile load test data for several instrumented piles to determine the load transfer characteristics of driven piles in soft so ils. Piles develop resistance to axial loads through two different mechanisms, side friction and end bearing. The rate that resistance develops is dependent upon soil type , pile type, and movement of the pile with respect to the soil. This thesis addresses load transfer for driven pipe piles in deep lacustrine deposits along the Wasatch Front area of Utah. The piles used in this study were installed for the support of highway structures in the Salt Lake City area. The information used in this study was obtained from the Utah Department of Transportation. Suggestions for pile capacity prediction are included as part of this study.

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Dong, K., D. P. Connolly, O. Laghrouche, P. K. Woodward, and Costa P. Alves. "The stiffening of soft soils on railway lines." Elsevier, 2018. https://publish.fid-move.qucosa.de/id/qucosa%3A73234.

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Railway tracks experience elevated rail deflections when the supporting soil is soft and/or the train speed is greater than approximately 50% of the wave propagation velocity in the track-soil system (i.e. the critical velocity). Such vibrations are undesirable, so soil replacement or soil improvement of the natural soil (or alternatively mini-piles or lime-cement treatment) is often used to increase track-ground stiffness prior to line construction. Although areas of existing soft subgrade might be easily identified on a potential new rail route, it is challenging to determine the type and depth of ground remediation required. Therefore, major cost savings can be made by optimising ground replacement/improvement strategies. This paper presents a numerical railway model, designed for the dynamic analysis of track-ground vibrations induced by high speed rail lines. The model simulates the ground using a thin-layer finite element formulation capable of calculating 3D stresses and strains within the soil during train vehicle passage. The railroad track is modelled using a multi-layered formulation which permits wave propagation in the longitudinal direction, and is coupled with the soil model in the frequency-wavenumber domain. The model is validated using a combination of experimental railway field data, published numerical data and a commercial finite element package. It is shown to predict track and ground behaviour accurately for a range of train speeds. The railway simulation model is computationally efficient and able to quickly assess dynamic, multi-layered soil response in the presence of ballast and slab track structures. Therefore it is well-suited to analysing the effect of different soil replacement strategies on dynamic track behaviour, which is particularly important when close to critical speed. To show this, three soil-embankment examples are used to compare the effect of different combinations of stiffness improvement (stiffness magnitude and remediation depths up to 5 m) on track behaviour. It is found that improvement strategies must be carefully chosen depending upon the track type and existing subgrade layering configuration. Under certain circumstances, soil improvement can have a negligible effect, or possibly even result in elevated track vibration, which may increase long-term settlement. However, large benefits are possible, and if detailed analysis is performed, it is possible to minimise soil improvement depth with respect to construction cost.

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Jeyakanthan, Velautham Engineering &amp Information Technology Australian Defence Force Academy UNSW. "Electro-osmotic stabilisation of soft soils : a numerical approach." Awarded by:University of New South Wales - Australian Defence Force Academy. Engineering & Information Technology, 2009. http://handle.unsw.edu.au/1959.4/44101.

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A numerical formulation for two-dimensional electro-osmotic consolidation in soft clays was derived from the basic equations of fluid flow, current flow and virtual work law. And, a well known elasto-plastic soil model, Modified Cam Clay was embedded into the formulation and implemented into the finite element program AFENA. The formulation was evaluated by comparing the predicted settlement and pore water pressure response with the values obtained from laboratory tests. The tests were conducted in an electro-osmotic triaxial apparatus, which was modified from a standard triaxial apparatus to facilitate electro-osmotic consolidation and required measurements. A series of electro-osmotic consolidation tests under different initial stress conditions were conducted to evaluate the finite element model and very good agreements between the observed and predicted results were observed. Another set of electro-osmotic tests were conducted with the similar initial stress, but different boundary conditions to examine the effects of electrochemical changes during the electro-osmosis. The study showed an apparent increase in the preconsolidation pressure and alteration in the coefficient of consolidation as a result of the electrochemical changes. A one-dimensional electro-osmotic consolidation problem was simulated and analysed, and the settlement and pore water pressure responses were compared with the solutions obtained from Esrig's (1968) one-dimensional theory. Another problem involving combined electro-osmotic and direct loading consolidation was also analysed and the results were compared with the solutions obtained from Wan and Mitchell's (1976) theory. Excellent matches were observed in both cases mentioned above for constant values of electro-osmotic and hydraulic permeabilities. However, the effects of varying electro-osmotic and hydraulic permeabilities, which are practically far more significant and not adopted in the theories mentioned above, were also analysed and the results presented. An attempt was made to simulate and analyse one of the successful field trial of electro-osmotic stabilisation conducted by Bjerrum et al (1967) on Norwegian quick clay. Good agreement between the predicted and reported settlement was observed for the first 50days of the treatment period. However, the model over-predicted the settlement after this period and the possible causes for this variation are discussed.

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Kamrat-Pietraszewska, Daniela. "Numerical modelling of soft soils improved with stone columns." Thesis, University of Strathclyde, 2011. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=23168.

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Natural soft soils are very complex materials and geological processes greatly influence their stress-strain behaviour. Natural soft soils exhibit anisotropy and interparticle bonding, and their stress-strain response is time-dependent. Taking account of those soil characteristics is paramount for realistic and accurate predictions of soft soil behaviour. Geotechnical properties of natural soft soils can be improved with various techniques, such as stone columns. Stone columns are mainly used for settlement and consolidation time reduction, however underneath an embankment stone columns also enhance the slope stability. Despite the wide range of applications of stone columns, current design methods of stone columns are for the greater part based on simple assumptions and do not account for the complex soil-column interaction. Numerical methods are still fighting for their place in industrial design. They could be used, as a complementary solution to well-known empirical design proc edures, for gaining a better understanding of the behaviour of soil improved with stone columns and for the optimisation of existing design procedures. Behaviour of a stone column foundation is largely governed by the surrounding soil, its compressibility characteristics and the stress-strain-strength response. The models commonly used by civil engineering practitioners predict often inaccurate and over-conservative stress-strain response, as characteristics of soft soils are ignored and the complexity of the soil-column interaction is neglected. The novelty of this research lies in accounting for the complex features of natural soft soil behaviour, such as non-linearity, anisotropy, destructuration and viscosity, in soil modelling. Following that, the work enables optimisation of the design of stone column foundations by reducing the risk of unexpected ground movements. Three-dimensional numerical studies on the effect of mechanical and physical properties of stone columns and the impact of soft soil layer thickness are carried out by application of advanced constitutive models to represent the soft soil mass. Additionally, the research aimed for the development of an advanced constitutive model which takes account of all important characteristics of soft soil, leading to more realistic predictions of soft soil behaviour. Next, the influence of anisotropy, apparent interparticle bonding and viscosity on predicted stress-strain response of the stone column foundation constructed on soft soil was studied via a three-dimensional benchmark problem and the application of advanced constitutive models.

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Panchal, Jignasha. "Minimising ground movements around deep excavations in soft soils." Thesis, City, University of London, 2018. http://openaccess.city.ac.uk/21044/.

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This research concerns the influence of a range of construction methods, acting at or below excavation formation level, on ground movements of the retained surface attributed to a 12m deep excavation in very soft to soft soil. Movements around excavations arise as a consequence of the removal of soil and lateral wall deformations. The work examined the behaviour of excavations that were supported by a high stiffness embedded retaining wall whilst modelling a variety of construction techniques. Four distinct construction methods were modelled which could be regarded as surcharging the formation level or stiffening the ground below excavation formation level. The specific techniques that were explored include underwater excavations, bermed excavations, deep soil mixing and double walled excavations. This study aimed to determine the efficiency of these construction measures on reducing the magnitude and extent of displacements occurring behind the retaining wall. Experimental data were obtained from twenty-two plane strain centrifuge model tests undertaken at 160g. The geometry of the model comprised a pre-formed excavation where the retaining wall was laterally supported by a continuous prop acting over the majority of the height of the wall and the excavation formation level was surcharged by a pressurised rubber bag. Pressure in the bag at formation level was reduced at a constant rate to simulate the stress change caused by the excavation process. Vertical movements at the retained ground surface were measured using displacement transducers whilst subsurface deformations elsewhere in the model were determined from the analysis of digital images captured by cameras viewing the front of the model through a Perspex window. The magnitude and extent of movements were quantified and the general patterns of ground deformation were identified for the construction methods implemented. A series of reference tests were conducted to provide a baseline against which modified excavation tests were compared. The stiff wall and continuous prop supporting the retaining wall ensured that the reference tests quantified the magnitude of displacements at the retained surface arising simply as a result of heave at the formation level. The main test series investigated a range of construction methods that aimed to surcharge or stiffen the formation level. Additional tests were also undertaken to evaluate the influence of wall embedment on the performance of the excavation system. Direct comparisons were also drawn between tests in an attempt to establish the significance of wall crest fixity on soil movements. The use of all of the special construction techniques investigated were shown to reduce the magnitude of vertical displacement behind the retaining wall and at the formation level; in addition to reducing horizontal displacements at the toe of the wall. Increasing the retaining wall embedment depth in the main test series generally reduced the magnitude of vertical settlement by a factor of two, however the effect was less pronounced in the reference tests. Improving the fixity of the crest of the wall delayed excavation collapse and, where additional support mechanisms were not employed, pinning the crest of the wall was shown to reduce maximum settlement in the reference test by a factor of three. Of the four supporting construction methods the underwater excavation was found to be the most effective owing to the reduced change in vertical stress during the simulated excavation. Various deep soil mixing geometries were modelled and similar excavation behaviour was observed, however deep soil mixing ground treatment extending to the toe of the retaining wall and across 2/3 of the excavation demonstrated a slight reduction in settlement. Similar behaviour was observed for double walled excavations. Combining underwater excavations with a double wall was shown to further reduce maximum settlements however little additional benefit was observed when performing an underwater excavation with a deep soil mixed soil layer at excavation formation level.

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Qi, Shunchao. "Numerical Investigation for Slope Stability of Expansive Soils and Large Strain Consolidation of Soft Soils." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/37019.

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Several geotechnical processes can only be reliably interpreted by taking account of the soil-atmosphere interactions. This thesis investigates two geotechnical problems involving soil-atmosphere interactions that drive water flow through the soil skeleton in two opposite directions; Problem 1: slope failure in expansive soils induced by water infiltration, Problem 2: large strain consolidation of soft soils induced by water evaporation. Both problems are of practical interest for safe and economical design of various geotechnical infrastructures. Two major geotechnical activities in the world; namely, the construction of water transfer canal in expansive soil area in China and the deposition of oil sands and hard rock tailings in Canada can be cited as classic examples of Problems 1 and 2, respectively. In such problems, substantial zones of the domain may switch between an unsaturated and saturated condition. Therefore, rational analysis requires simultaneous modelling of both unsaturated and saturated soil behaviour. The first goal of this thesis is to investigate the influence of swelling (the most characteristic behaviour of expansive soils) on slope stability using numerical methods. Swelling of expansive soils contributes to slope instability during rainfall because of two key reasons (i) soil swelling affects the flow process that actually induces swelling, (i.e. a typical coupling phenomenon), and (ii) swelling-induced stress redistribution and displacement development. In this thesis, the first effect is studied by a coupled (mechanical-hydraulic) numerical analysis of the response of a slope to rainfall using commercial software (GeoSlope). The second effect, the swelling-induced stress redistribution and displacement development after wetting, is tracked using a newly developed numerical program. In the program strain softening behaviour is introduced into the elasto-plastic Mohr-Coulomb Model for modelling unsaturated soil. A novel stress (net stress and suction)-dependent model for moduli of elasticity, combined with the predictive model for shear strength based on Soil Water Retention Behaviour are incorporated into the numerical program to achieve a smooth transition between saturated and unsaturated states. The results show that soil swelling can decrease the factor of safety by accelerating the wetting front depth due to hydro-mechanical coupling, while changes of sliding mass geometry has a negligible influence. The change of stress regime associated with soil swelling is significant to induce plastic strain softening (swelling-induced softening) and contribute to the slope failures. The second goal of thesis is to develop a novel computer program for simulation of large strain consolidation of soft soil under both self-weight and evaporation conditions. This program is both theoretically sound and practically applicable. Several basic/advanced constitutive models for unsaturated soils, including State Surface Model (SSM), Barcelona Basic model (BBM), Glasgow Coupled model (GCM) and bounding surface water retention model, are innovatively implemented into a piece-wise linear framework solved using finite difference technique. The developed program is referred to as UNSATCON-(ML), which has been tested using (a) existing analytical/numerical solutions and (b) various laboratory and field studies for single-layer and multiple-layer deposition of hard rock and oil sands tailings. Features of UNSATCON-(ML) that are improvements over existing models typically used to analyze consolidation-desiccation in soft soils include: (i) coupling of soil large deformation with true unsaturated water flow; (ii) correct reproduction of the shrinkage behaviour of soil under evaporation-induced desiccation; (iii) smooth transition between saturated and unsaturated states despite that some selected models are established using two independent stress variables, (iv) ensuring strictly mass conservation of water, and (v) simulation of irrecoverable volume change and hydraulic hysteresis to properly analyze multilayer tailings deposition. A number of hypothetical field case analyses are carried out using UNSATCON-ML, illustrating its applicability to industry.

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Dienstmann, Gracieli. "Projeto interativo dos molhes da Barra do Rio Grande-RS." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2011. http://hdl.handle.net/10183/32005.

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O presente trabalho detalha o conceito de Projeto Interativo aplicado à obra de ampliação dos Molhes da Barra do Rio Grande-RS, uma das maiores obras de infraestrutura portuária do Brasil, a qual se desenvolve em substrato argiloso de baixa capacidade de suporte e elevada compressibilidade, com espessura média de 10m. A obra de ampliação dos molhes e sua estratigrafia são detalhados após a revisão de critérios de alerta aplicados à aterros sobre solos moles. Posteriormente com o intuito de aferir modelos, fez-se uma análise da sensibilidade dos parâmetros de projeto, através da aplicação dos conceitos de segurança segundo o Método dos Volumes Deslocados, a qual definiu que a relação de volumes deslocados (dVv/dVh - razão de volume vertical deslocado, dVv, por volume horizontal deslocado, dVh) é suscetível às condições de drenagem, aos parâmetros de resistência e compressibilidade do solo de fundação, da geometria da área carregada e dos locais onde as leituras são realizadas. A dependência das leituras a este conjunto de fatores reforça a necessidade de análises numéricas específicas para definição de níveis de alerta. A análise paramétrica observou também que a aferição de parâmetros deve ser feita distintamente entre parâmetros de resistência e compressibilidade. De posse destas observações foram aferidos os parâmetros de projeto. Sequencialmente fez-se a reavaliação das seções de simulação numérica através de uma retroanálise quando do alteamento dos molhes à cota +2m. Observou-se que as simulações conseguiram capturar o comportamento em campo, em termos de deslocamentos horizontais e verticais, distorções e poro pressão. Este procedimento foi repetido até a fase de fechamento dos molhes, retroanalisando-se etapas anteriores de construção para refinar a estimativa das etapas subsequentes, garantindo-se as condições de segurança da obra. Com base neste estudo apresenta-se uma discussão quanto à postulação de critérios de segurança em obras geotécnicas, observando que estes devem ser abrangentes, de acordo com as características da obra, definindo deformações máximas e controle de taxas de deformação e, em particular, a taxa de distorção que cresce linearmente próximo à ruptura e diminui quando do aumento da estabilidade durante o período de adensamento.
The concept of Interactive Design applied to a marine breakwater in Rio Grande-RS, southern Brazil, is described in the present paper. Besides a literature review concerning constructions control methods applied in soft soil embankments, the characteristics of the site and construction work are presented and, the stratigraphy is detailed, which is characterized by a soft foundation substrate of low capacity and high compressibility, with a thickness about 10m. Based on the need to postulate security levels in geotechnical projects, according the soft layer that support the current construction, the first steep was to perform a parametric evaluation of the breakwater using the Displaced Volume Method, a field stability control for embankments on soft soil. This parametric analyses shows that dVv/dVh (ratio of vertical volume displaced, dVv, per horizontal volume displaced, dVh) is a function of drainage conditions, strength and compressibility parameters, loaded area geometry, and location of measured points. The analysis is shown to be particularly sensitive to friction angle and compressibility .Given the sensitivity of the security analysis to several different parameters and geometrical conditions, it has been stressed that specific numerical analysis should be performed for every geotechnical problem. Using these observations, soil foundation parameters, obtained in the breakwater region, were checked, and recalibrated. After that, some back analysis to verify the models was made in all instrumentation sections. It was observed that the simulations were able to capture the measured behavior of horizontal and vertical displacements, distortions, and pore pressures. The analysis was repeated for different construction phases, so that a back-analysis of a previous stage could refine the predictions of the following stage. Finally, a field control is presented according to acceptable ranges of displacements, distortion and specially distortions rates, which increases linearly near the failure and decreases when increasing stability due to consolidation effects.

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COBE, REBECCA PEZZODIPANE. "BEHAVIOR OF AN EMBANKMENT CONSTRUCTED ON A SOFT CLAY FOUNDATION AND ITS INFLUENCE ON THE ADJACENT PILES." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2017. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=36574@1.

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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO
COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
PROGRAMA DE EXCELENCIA ACADEMICA
Este estudo analisa o caso de um aterro experimental construído em escala real ao lado de um estaqueamento, em um terreno composto por uma espessa camada de argila mole, situado na baixada de Jacarepaguá, Rio de Janeiro. No local do aterro, foi realizada uma vasta investigação geotécnica e um monitoramento composto por placas de recalque, piezômetros e inclinômetros instalados ao longo da profundidade do terreno e das estacas adjacentes ao aterro. O movimento horizontal do solo na extremidade do aterro devido à natureza assimétrica do carregamento gera esforços ao longo da profundidade das estacas instaladas na adjacência dessa sobrecarga. Esse fenômeno, conhecido na literatura brasileira como Efeito Tschebotarioff é influenciado por diversos fatores, entre eles pelo adensamento do solo, pelo efeito de grupo e pela distância do estaqueamento em relação à base do aterro, cujas análises de suas influências fazem parte do objetivo desse trabalho. A influência do adensamento no desenvolvimento dos deslocamentos horizontais em profundidade foi analisada com base nos resultados obtidos por meio da instrumentação de campo. Já as influências do efeito de grupo e da distância do estaqueamento em relação à base do aterro foram analisadas por meio de uma análise numérica bidimensional utilizando o programa Plaxis 2D. Os resultados da instrumentação mostraram que a razão entre os deslocamentos horizontais máximos e os recalques é de cerca de 0,16 ao longo de todo o alteamento do aterro. Com relação à modelagem numérica, seus resultados mostraram que o efeito de grupo pode reduzir os deslocamentos horizontais nas estacas traseiras em cerca de 14 por cento e os momentos fletores em até 58 por cento. Além disso, foi observado que os deslocamentos horizontais e esforços nas estacas somente podem ser considerados desprezíveis a partir de distâncias correspondentes a cerca de 2,5 vezes a espessura de solo mole.
This study analyzes the case of an experimental embankment constructed in real scale alongside a pile group in a field composed of a thick layer of soft clay, located in the lowland of Jacarepaguá, Rio de Janeiro. The monitoring of the experiment was composed by settlement plates, piezometers and inclinometers installed throughout the depth of the ground and piles adjacent to the embankment. The horizontal movement of the soil at the border of the embankment generates stresses along the depth of the piles installed adjacent to the surcharge due to the asymmetric nature of this load. This phenomenon, known in the Brazilian literature as the Tschebotarioff Effect, is influenced by several factors. In this work, the influence factors that were studied are the soil consolidation, the group effect and the distance of the piles from the base of the embankment. The influence of the consolidation on the development of deep horizontal displacements was analyzed based on the results obtained through field instrumentation. On the other hand, the influence of the group effect and the distance of the piles from the embankment base were analyzed using a two-dimensional numerical analysis in the Plaxis 2D program. The results of the instrumentation showed that the ratio between the maximum horizontal displacements and the settlements is around 0,16 throughout the entire embankment elevation. Regarding numerical modeling, their results showed that the group effect can reduce horizontal displacements in the rear piles by around 14 per cent and the bending moments by up to 58 per cent. In addition, it has been observed that horizontal displacements and stresses on the piles can only be considered negligible from distances corresponding to about 2.5 times the soft soil thickness.

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Kidwaro, Fanson Majani. "Stabilized nitrogen management for soft red winter wheat production in Missouri /." free to MU campus, to others for purchase, 1996. http://wwwlib.umi.com/cr/mo/fullcit?p9717167.

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Al-Alwan, Asad A. Khedheyer. "Undrained shear strength of ultra-soft soils admixed with lime." Thesis, University of Glasgow, 2019. http://theses.gla.ac.uk/40931/.

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This thesis describes the results of a study on the undrained shear strength (Cu) of ultra-soft clay soils in admixtures of calcium hydroxide (slaked-lime). The pozzolanic gains in strength over time, over periods as long as one year were recorded. The undrained shear strengths were measured primarily using penetration tests: a Tinius Olsen desk-top compression machine was modified to conduct these constant-rate of strain tests, using circular disc penetrometers. Measured bearing resistances were interpreted in terms of undrained shear strengths: data from the literature, as well as some finite element analyses, were employed to establish the necessary depth-dependent correlations. The strength testing programme was supplemented by triaxial compression and vane shear tests. The parametric study of the factors affecting the strength of lime-admixed clay slurries included soil type, water content, lime content, curing time, and curing temperature. The results show how the rate of strength gain is affected by soil mineralogy. The greatest strength gains can only occur if sufficient clay fractions are present to utilize any unbound additive and conversely sufficient additive is present. For clays, samples prepared at the same water content/ liquid limit ratio (W=w /wLL) produced approximately the same undrained shear strength after one year of curing. Tests were also conducted on remoulded samples: as expected, these admixed soils have high sensitivity. However, remoulding is not achieved without the expenditure of considerable work. Moreover, the remoulded strengths remain some orders of magnitude higher than their untreated counterparts. Diffusion of additive from the admixture into surrounding water was observed; this was manifest in softening of the near-surface material and over a period of one year extended to depths of the order of 10 cm depending on lime content. Curing temperature has a significant effect on the rate of strength development. Lower curing temperatures retard strength development while higher temperatures have the opposite effect. The Arrhenius model for the rates of chemical reactions describes this temperature dependent phenomenon very satisfactorily. Finite element studies, including small-strain Lagrangian and coupled Eulerian-Lagrangian large-displacement formulations (incorporated within ABAQUS) were conducted to investigate whether penetrometer data interpretation required consideration of the finite size of the test chamber. These numerical results tended to confirm the experimental finding that penetrometer disk diameters up to 30 mm were sufficiently small to be unaffected by constraints imposed by the test chambers. In addition, oedometer testing was carried out on both intact and remoulded samples. The former revealed the existence of reasonably well-defined "yield stresses", which were found to correlate well with the corresponding undrained shear strengths. The compression and swell indices were found to be largely dependent on soil type and correspondingly unaffected by lime content.

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38

Rafalko, Susan Dennise. "Rapid Soil Stabilization of Soft Clay Soils for Contingency Airfields." Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/35985.

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Since World War II, the military has sought methods for rapid stabilization of weak soils for support of its missions worldwide. Over the past 60 years, cement and lime have consistently been found to be among the most effective stabilizers for road and airfield applications, although recent developments show promise using nontraditional stabilizers. The purpose of this research is to determine the most effective stabilizers and dosage rates of stabilizers to increase the strength of soft clay soils (initial CBR = 2) within 72 hours for contingency airfields to support C-17 and C-130 aircraft traffic. Pavement design charts for various aircraft loading conditions were generated using the Pavement-Transportation Computer Assisted Structural Engineering Program, which was developed by the Engineering Research and Development Center to determine ranges of required strength and thickness for an underlying subbase layer and a top base layer, such as stabilized soil, crushed-aggregate, or aluminum matting. From laboratory studies, the required design strengths for many loading conditions were achieved by treating clay with 2%-4% pelletized quicklime for the underlying subbase layer, and treating clay with 2%-4% pelletized quicklime, 1% RSC15 fibers, and 11% Type III cement for the top base layer. While the base layer requires a minimum thickness of six inches, the required subbase layer thickness is often quite large and may be difficult to construct. However, newly developed construction equipment currently used for subgrade stabilization on civilian projects should be able to stabilize the soil down to these large required depths and make construction possible.
Master of Science

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39

Glendinning, Stephanie. "Deep stabilisation of slopes using lime piles." Thesis, Loughborough University, 1995. https://dspace.lboro.ac.uk/2134/6951.

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A comprehensive review of the literature provided much evidence of the success of lime piles in treating both soft ground and slopes. The mechanisms of stabilisation postulated by researchers is often contradictory or misleading. The use of the literature for the basis of a definitive experimental programme was not possible. An iterative approach was adopted for the laboratory programme whereby the results from one series of tests were used in the design of the next. This resulted in a range of tests including full-scale box loading tests in which lime piles were installed in clay samples, model scale lime pile tests and soil element tests. The stabilising mechanisms that have been established by the laboratory study are: generation of negative pore water pressure, overconsolidation of the shear zone, clay dehydration, pile strength and increased strength of stabilised clay due to lime migration. These mechanisms combine to improve any particular clay slope containing one or more shear zones. Three field trials were conducted. A small-scale trial was carried out on a canal cutting and provided useful data regarding pore water pressure changes and installation processes. Quantitative data produced by the laboratory study, were used to design two further trials. One trial treated a 30 m stretch of failing slope using a single 'Minuteman' rig (small and lightweight plant). Quicklime was 'poured' into open holes and compacted by the drill operators. Work was complete within two weeks. The third trial, again sited on a canal cutting, was carried out using a much larger rig. One hundred and fifty 200 mm diameter piles were constructed to a depth of 3 metres within a two week period. Monitoring of pore water pressures on both sites is still occurring on a regular basis. Excavation of sections of both trials at some future date will provide additional data on stabilising mechanisms. The research has considerably extended the understanding of the mechanisms controlling lime pile stabilisation, particularly when applied to failing slopes in British soils. Areas where further research would improve this understanding have been highlighted and in some cases work is already underway.

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Shi, Han. "Numerical simulations and predictive models of undrained penetration in soft soils." Texas A&M University, 2005. http://hdl.handle.net/1969.1/2555.

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There are two aspects in this study: cylinder penetrations and XBP (Expendable Bottom Penetrometer) interpretations. The cylinder studies firstly investigate the relationship between the soil resisting force and penetration depth by a series of rateindependent finite element analyses of pre-embedded penetration depths, and validate the results by upper and lower bound solutions from classical plasticity theory. Furthermore, strain rate effects are modeled by finite element simulations within a framework of rate-dependent plasticity. With all forces acting on the cylinder estimated, penetration depths are predicted from simple equations of motion for a single particle. Comparisons to experimental results show reasonable agreement between model predictions and measurements. The XBP studies follow the same methodology in investigating the soil shearing resistance as a function of penetration depth and velocity by finite element analyses. With the measurements of time decelerations during penetration of the XBP, sediment shear strength profile is inferred from a single particle kinetic model. The predictions compare favorably with experimental measurements by vane shear tests.

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Chan, Chee-Ming. "A laboratory investigation of shear wave velocity in stabilised soft soils." Thesis, University of Sheffield, 2006. http://etheses.whiterose.ac.uk/15165/.

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The stabilisation of soft clay soils is intended to increase their shear strength and to reduce their compressibility. The possibility exists of using geophysical methods to monitor changes in these properties. Laboratory experiments were carried out on stabilised clays to study the relationships between shear wave velocity, and hence small strain shear stiffness, and shear strength or one-dimensional compressibility. One artificial clay, Speswhite kaolin, and two natural clays, from Malaysia and Sweden, were used as the base clays. Either ordinary Portland cement or a 1: 1 mix of the cement with unslaked lime was added to the base clays in order to stabilize them. In the first part of the investigation, samples of stabilised clay were initially subjected to a non-destructive bender element test to obtain the shear wave velocity and then to an unconfined compressive strength test or vane shear strength test. It was evident that small stabiliser amounts (less than 10 % of the dry weight of the base clay) could significantly improve both the strength and stiffness of the originally soft material. In addition, good correlations between the shear strength and the shear wave velocity (or small strain shear stiffness) of the stabilised clays were established. In the second part of the investigation, an instrumented oedometer was used to simultaneously monitor shear wave velocity and one-dimensional compression during tests on samples cured for a set period. Lateral stresses were also measured. Complementary tests were conducted in standard oedometers, to study the effect of the curing period. In these tests yield stresses were identified and corresponded to the onset of changes in shear wave velocity. After yield, the constrained moduli could be correlated with shear wave velocity. Tests were also carried out on samples of clay in which a central stabilised column had been created. Equal strain predictions of the compression of these samples, based on the results of separate tests on the two components, were relatively successful. The results of the research suggest that shear wave velocity measurements could be useful in practice to enable the shear strength and post-yield compressibility of stabilised clay soil to be estimated.

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El-Bahey, Mohamed Essam. "The consolidation of soft clays : an experimental and analytical investigation." Thesis, University of Southampton, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.278906.

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de, Martin Florent. "Influence of the nonlinear behaviour of soft soils on strong ground motions." Phd thesis, Ecole Centrale Paris, 2010. http://tel.archives-ouvertes.fr/tel-00534807.

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Le comportement nonlinéaire des sols observé lors des mouvements sismiques forts est maintenant bien admis et le déploiement des puits accélérométriques a permis des analyses détaillées de la propagation des ondes ainsi qu'une évaluation quantitative des paramètres physiques tels que la vitesse de cisaillement et de compression des ondes et les facteurs d'amortissements en fonction de la déformation. En dépit du nombre grandissant d'études sur ce phénomène, sa connaissance est encore récente et les recherches sur les données de puits accélérométriques restent une étape importante vers la compréhension du comportement complexe in-situ des sédiments soumis à des mouvements sismiques forts.L'objectif de ces travaux est triple. Premièrement, un code d'inversion par algorithme génétique est développé afin d'inverser des données de puits accélérométriques via la théorie des matrices de propagation de Thomson-Haskell. Cette technique nous permet dans un premier temps de valider la structure en une dimension (1D) (e.g., vitesse des ondes de cisaillement, facteurs d' amortissements) d'un puits accélérométrique dans le domaine linéaire et dans un second temps de mettre en évidence de manière quantitative le comportement nonlinéaire des sédiments lors du séisme de Fukuoka, 2005, Japon. Deuxièmement, les résultats de l'inversion sont utilisés pour tester des lois de comportement simples et avancées en utilisant la Méthode des éléments Finis. Les résultats montrent clairement que l'hypothèse bi-linéaire de la loi de comportement simple produit des séries temporelles non réalistes en vitesse et en accélération. L'utilisation d'une loi de comportement avancée mène à de meilleurs résultats, cependant, le nombre de paramètres ajustables pour obtenir des résultats consistants avec l'observation est un obstable inévitable. Troisièmement, afin d'étendre l'étude des effets de site à des dimensions supérieures, des codes 2D et 3D de la Méthode en éléments Spectraux sont développés et validés en comparant leurs résultats dans le domaine linéaire avec ceux obtenus théoriquement ou via d'autres méthodes numériques.

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Gebreselassie, Berhane. "Experimental, analytical and numerical investigations of excavations in normally consolidated soft soils." Kassel : Kassel Univ. Press, 2003. http://d-nb.info/991644018/34.

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Rothhämel, Mirja. "Near-surface soil stabilisation to reduce the frost susceptibility of soft soils." Licentiate thesis, Luleå tekniska universitet, Geoteknologi, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-71219.

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46

Martin, Florent de. "Influence of the nonlinear behaviour of soft soils on strong ground motions." Thesis, Châtenay-Malabry, Ecole centrale de Paris, 2010. http://www.theses.fr/2010ECAP0013/document.

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Le comportement nonlinéaire des sols observé lors des mouvements sismiques forts est maintenant bien admis et le déploiement des puits accélérométriques a permis des analyses détaillées de la propagation des ondes ainsi qu’une évaluation quantitative des paramètres physiques tels que la vitesse de cisaillement et de compression des ondes et les facteurs d’amortissements en fonction de la déformation. En dépit du nombre grandissant d’études sur ce phénomène, sa connaissance est encore récente et les recherches sur les données de puits accélérométriques restent une étape importante vers la compréhension du comportement complexe in-situ des sédiments soumis à des mouvements sismiques forts.L’objectif de ces travaux est triple. Premièrement, un code d’inversion par algorithme génétique est développé afin d’inverser des données de puits accélérométriques via la théorie des matrices de propagation de Thomson-Haskell. Cette technique nous permet dans un premier temps de valider la structure en une dimension (1D) (e.g., vitesse des ondes de cisaillement, facteurs d’ amortissements) d’un puits accélérométrique dans le domaine linéaire et dans un second temps de mettre en évidence de manière quantitative le comportement nonlinéaire des sédiments lors du séisme de Fukuoka, 2005, Japon. Deuxièmement, les résultats de l’inversion sont utilisés pour tester des lois de comportement simples et avancées en utilisant la Méthode des éléments Finis. Les résultats montrent clairement que l’hypothèse bi-linéaire de la loi de comportement simple produit des séries temporelles non réalistes en vitesse et en accélération. L’utilisation d’une loi de comportement avancée mène à de meilleurs résultats, cependant, le nombre de paramètres ajustables pour obtenir des résultats consistants avec l’observation est un obstable inévitable. Troisièmement, afin d’étendre l’étude des effets de site à des dimensions supérieures, des codes 2D et 3D de la Méthode en éléments Spectraux sont développés et validés en comparant leurs résultats dans le domaine linéaire avec ceux obtenus théoriquement ou via d’autres méthodes numériques
Nonlinear behavior of soft soils observed during strong ground motions isnow well established and the deployment of vertical arrays (i.e., boreholestations) has contributed to detailed wave propagation analyses and the assessmentfor quantitative physical parameters such as shear-wave velocity,pressure-wave velocity and damping factors with respect to shear strain levels.Despite the growing number of studies on this phenomena, its knowledgeis still recent and research on borehole station data remains an importantstep toward the understanding of the complex in-situ behavior of soft sedimentssubjected to strong ground motions.The purpose of this work is threefold. First, an inversion code by geneticalgorithm is developed in order to inverse borehole stations data viathe Thomson-Haskell propagator matrix method. This technique allows usto validate the one-dimensional (1D) structure (e.g., shear-wave velocity,damping factors) of a borehole in the linear elastic domain and to showquantitative evidence of the nonlinear behavior of the soft sediments duringthe 2005 Fukuoka Prefecture western offshore earthquake, Japan. Second,the results of the inversion are used in order to test simple and advancedconstitutive laws using the Finite Elements Method. The results clearlyshow that the bi-linear assumption of the simple constitutive law producesunrealistic velocity and acceleration time histories. The use of the advancedconstitutive law leads to better results, however, the number of parametersto be tuned in order to obtain results consistent with the observation is anunavoidable obstacle. Third, in order to extend the study of site effects tohigher dimensions, 2D and 3D codes of the very efficient Spectral ElementsMethod are developed and validated by comparing their results in the lineardomain with those obtained theoretically or with other numerical methods

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47

Low, Han Eng. "Performance of penetrometers in deepwater soft soil characterisation." University of Western Australia. School of Civil and Resource Engineering, 2009. http://theses.library.uwa.edu.au/adt-WU2010.0008.

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Offshore developments for hydrocarbon resources have now progressed to water depths approaching 2500 m. Due to the difficulties and high cost in recovering high quality samples from deepwater site, there is increasing reliance on in situ tests such as piezocone and full-flow (i.e. T-bar and ball) penetration tests for determining the geotechnical design parameters. This research was undertaken in collaboration with the Norwegian Geotechnical Institute (NGI), as part of a joint industry project, to improve the reliability of in situ tests in determining design parameters and to improve offshore site investigation practice in deepwater soft sediments. In this research, a worldwide high quality database was assembled and used to correlate intact and remoulded shear strengths (measured from laboratory and vane shear tests) with penetration resistances measured by piezocone, T-bar and ball penetrometers. The overall statistics showed similar and low levels of variability of resistance factors for intact shear strength (N-factors) for all three types of penetrometer. In the correlation between the remoulded penetration resistance and remoulded shear strength, the resistance factors for remoulded shear strength (Nrem-factors) were found higher than the N-factors. As a result, the resistance sensitivity is less than the strength sensitivity. The correlations between the derived N-factors and specific soil characteristics indicated that the piezocone N-factors are more influenced by rigidity index than those for the T-bar and ball penetrometers. The effect of strength anisotropy is only apparent in respect of N-factors for the T-bar and ball penetrometers correlated to shear strengths measured in triaxial compression. On the other hand, the Nrem-factors showed slight tendency to increase with increasing strength sensitivity but were insensitive to soil index properties. These findings suggest that the full-flow penetrometers may be used to estimate remoulded shear strength and are potentially prove more reliable than the piezocone in estimating average or vane shear strength for intact soil but the reverse is probably true for the estimation of triaxial compression strength.

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Cheng, Fung-kiu Patty. "A computer aided design approach for evaluation of consolidation with vertical drains in soft clays /." Hong Kong : University of Hong Kong, 1995. http://sunzi.lib.hku.hk/hkuto/record.jsp?B19592395.

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Ting, Chi Man Roger. "Controlled gradient consolidation of soft soils with reference to the development of Kâ†o." Thesis, University of East London, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.258762.

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Sengor, Mahmut Yavuz. "The Deformation Characteristics Of Deep Mixed Columns In Soft Clayey Soils: A Model Study." Phd thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613075/index.pdf.

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Deep Mixing involves the introduction of cementitious or specially formulated solutions directly into the ground through the use of purpose built blending injection augers. The system is mainly designed to increase strength and reduce compressibility of treated soil. In the first stage of the research effective mixture ratios and mixture types of stabilizing agents were investigated for soft clays (CL form Eymir lake and kaolinite) by means of unconfined compression (UC) tests on stabilized soils. The unconfined compressive strength (UCS) values were obtained for 7,28,90 and 365 days of curing time. The ratio of elastic modulus at 50% failure load (E50) to (UCS) of the stabilizing agents were also investigated. In the second part of the research programme, deep mixed model columns with the three column materials and four different column spacings are formed within the large scale consolidation tanks, and the consolidation characteristics of deep mixed improved clay were investigated. Based on the results of large scale consolidation tests on deep mixed columnar improved soft clay, compressibility characteristics of improved soft clay were determined in relation to spacing of columns namely, effective replacement ratio and binder content. The cement content (also UCS) of the column material was found to be the most important parameter for the improvement effects of DMM applications. Validity of the relations for the estimation of bulk compression modulus of soilcrete were discussed. The use of constrained modulus of the soil and the column material were found to be effective in predicting the compression modulus of the soilcrete. Settlement reduction factor versus replacement ratio and cement content relations were determined which may be used for preliminary design works. The stresses on the soil and the columns were backcalculated from the settlement values. The stress ratios were obtained.

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