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Serviceability-based design approach for reinforced embankments on soft clayPanesar, Harpreet Singh 14 June 2005
The mechanism of soil-reinforcement interaction for a reinforced embankment on soft clay has been explored by conducting a parametric study using a coupled non-linear elastoplastic finite element program. One of the major issues in the design of a reinforced embankment on soft clay is the magnitude of tension that can be mobilized in the geosynthetic reinforcement. Previous research using geotechnical centrifuge modelling and present research using finite element modelling has confirmed that the tension mobilized in the reinforcement is only of the order of active lateral thrust in the embankment. The parametric study has revealed that the soil-reinforcement interaction mechanism depends on the ratio of embankment height to the depth of the clay layer. The embankment behaves similar to a rigid footing in case of deep clay deposit. In this case, the failure mechanism is similar to a slip circle and there is very little contribution from the clay-reinforcement interface towards the mobilization of reinforcement tension. However, if the depth of clay deposit is small, the soil-reinforcement interaction mode is similar to direct shear failure and slip surface is located close to the clay-reinforcement interface. In this case, the contribution of clay-reinforcement interface towards the tension mobilized in the reinforcement is higher and therefore, the contribution of the reinforcement towards overall stability of the embankment is greater. Based on the results of the parametric study a novel serviceability criterion is proposed that aims to limit the lateral deformation of the clay foundation at the toe of the embankment by limiting the allowable mobilized tension in the reinforcement. A simple procedure for the evaluation of the efficiency of soil-reinforcement interface for reinforced embankments on soft clays is also proposed. The validity of the proposed serviceability criterion and the design charts was successfully tested using two field case studies. Sackville test embankment constructed to failure in 1989 and a levee test section that remained serviceable after construction in 1987 at Plaquemine, Louisiana were able to confirm the validity of the serviceability criterion proposed in the present study.
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Serviceability-based design approach for reinforced embankments on soft clayPanesar, Harpreet Singh 14 June 2005 (has links)
The mechanism of soil-reinforcement interaction for a reinforced embankment on soft clay has been explored by conducting a parametric study using a coupled non-linear elastoplastic finite element program. One of the major issues in the design of a reinforced embankment on soft clay is the magnitude of tension that can be mobilized in the geosynthetic reinforcement. Previous research using geotechnical centrifuge modelling and present research using finite element modelling has confirmed that the tension mobilized in the reinforcement is only of the order of active lateral thrust in the embankment. The parametric study has revealed that the soil-reinforcement interaction mechanism depends on the ratio of embankment height to the depth of the clay layer. The embankment behaves similar to a rigid footing in case of deep clay deposit. In this case, the failure mechanism is similar to a slip circle and there is very little contribution from the clay-reinforcement interface towards the mobilization of reinforcement tension. However, if the depth of clay deposit is small, the soil-reinforcement interaction mode is similar to direct shear failure and slip surface is located close to the clay-reinforcement interface. In this case, the contribution of clay-reinforcement interface towards the tension mobilized in the reinforcement is higher and therefore, the contribution of the reinforcement towards overall stability of the embankment is greater. Based on the results of the parametric study a novel serviceability criterion is proposed that aims to limit the lateral deformation of the clay foundation at the toe of the embankment by limiting the allowable mobilized tension in the reinforcement. A simple procedure for the evaluation of the efficiency of soil-reinforcement interface for reinforced embankments on soft clays is also proposed. The validity of the proposed serviceability criterion and the design charts was successfully tested using two field case studies. Sackville test embankment constructed to failure in 1989 and a levee test section that remained serviceable after construction in 1987 at Plaquemine, Louisiana were able to confirm the validity of the serviceability criterion proposed in the present study.
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Reduction in Wick Drain Effectiveness in Typical Utah ClaysSmith, Gabriel M. 09 December 2011 (has links) (PDF)
Consolidation theory states that decreasing the spacing of prefabricated vertical drains will decrease the time required to achieve primary consolidation. Previous field tests have shown that there exists a "critical" drain spacing, which is the point at which further spacing decrease does not decrease the time of primary consolidation. This "critical" spacing is thought to be due to disturbance effects from installation of the drains. Previous studies have found that the "critical" drain spacing may be dependent upon soil layering and drain and mandrel dimensions. Thin, interbedded clay layers have been found to be affected greatly due to the smear zone, while few tests have been conducted to determine the validity for thick bedded clays. Currently two design and analysis methods are in existence, neither of which is standardized. The two methods are the modeling of the smear zone, which requires knowledge of soil parameters within that zone, and the modeling using a back-calculated Ch/Cv ratio.In order to evaluate the validity of these design methods and to obtain more data that can be used in determining the relationship between anchor type, drain spacing, and soil profile, full-scale field tests were conducted at Mountain View Corridor in Lehi, Utah. These field tests were performed along a test section that was divided into sections containing 5.8, 5.0, 4.0 and 3.0 ft triangular spacings and rebar or plate anchors. By using the smear zone model, with a Ch/Cv ratio of 1.25 and ds of 3.07 times dm, the time rate of settlement was able to be predicted reasonably well, while using the back-calculated Ch/Cv ratio, with no smear zone, also predicted the time rate reasonably well. From the testing, it was found that the thick clay profile can facilitate closer spacings than a thin clay profile. Also, it was found that the rebar anchor type causes about twice the disturbance of the plate anchor. The results helped validate the existing models and show that the effectiveness of the drains is dependent upon drain spacing, soil profile, and anchor type
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Estudo da resistência e consolidação de uma argila mole da Cidade de João Pessoa. / A study of the strength and consolidation of a soft clay from the City of João Pessoa.CONCEIÇÃO, Antonio Cristino da. 01 October 2018 (has links)
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ANTONIO CRISTINO DA CONCEIÇÃO - DISSERTAÇÃO PPGECA 1977..pdf: 27409984 bytes, checksum: 5912f51eef9d8359747739e237cf1e66 (MD5)
Previous issue date: 1977-07 / Este praqalho, trata do estudo dos parâmetros de resistência e consolidação de uma argila mole que faz parte do subsolo da cidade de João Pessoa. Da literatura consultada, apresentam-se dados e conclusões de estudos realizados em outras regiões, relacionados com o presente trabalho, onde destacamos principalmente os fatores fundamentais que influenciam sobre a resistência ao cisalhamento e a compressibilidade do solos argiloso. presenta-se uma pequena descrição dos aspectos geológicos do subsolo da região em estudo. Em uma camada de 12.00 metros de espessura, foram colhidas amostras do subsolo a cada metro de profundidade pelo uso de tubos de paredes finas tipo Shelby. Os ensaios de laboratório consistiram de: ensaio de caracterização do solo, ensaio de palheta (Vane Test), consolidação, compressão não confinada, triaxial não consolidado não drenado e consolidado drenado. As avaliações de resistência no campo, foram efetuadas através de três tipos de ensaios: ensaio de palheta
(Vane Test), penetrõmetro estático (Deep Sounding) e o penetrômetro dinâmico (SPT). O solo é caracterizado como uma argila siltosa, apresentando alta plasticidade e compressibilidade. 0 estudo mostra ainda, que a argila apresenta um pequeno aumento da resistência ao cisalhamento ao longo da profundidade. A argila exibe baixa permeabilidade. Utilizou-se o processo estatístico de regressão linear, para analisar possíveis correlações entre os parâmetros encontrados in situ e no laboratório. Esta análise mostra que dentro das limitações do estudo, existem boas correlações entre alguns parâmetros determinados. / his research studies the strength and consolidation parameters of a soft clay that forms part of the subsoil of the city of João Pessoa. From the literature consulted those topics which have direct bearing on this study were presented, the funda mental factors which influence the shear strength and the compressibility of this soil were elaborated. The geological aspects of the sub soil are described briefly. From a soil layer of 12.00 m thickness samples were collected from each meter of depth using thinwalled Shelby tubes.
The laboratory tests consisted of: vane shear, consolidation , unconfined compression, unconsolidated undrained and Consolidated drained triaxial tests, soil classification tests were also performed. In the field: vane shear, static ánd dynamic penetrometer tests were carried out. The soil was classified as a silty clay, having a high plasticity and compressibi1ity. The 1ow shear strength increased slightly with depth. The clay exhibited a low permeability.
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[en] COMPRESSIBILITY CHARACTERISTICS OF A SOFT CLAY FROM THE SANTA CRUZ INDUSTRIAL ZONE, RIO DE JANEIRO / [pt] CARACTERÍSTICAS DE COMPRESSIBILIDADE DE UMA ARGILA MOLE DA ZONA INDUSTRIAL DE SANTA CRUZ, RIO DE JANEIROANA CAROLINA SOUZA LIMA DE CAMPOS 23 May 2007 (has links)
[pt] Um amplo trabalho de pesquisa, envolvendo extensivas
investigações de
campo e laboratório de um depósito de argila mole
localizado na Zona Industrial
de Santa Cruz, Rio de Janeiro, RJ, vem sendo desenvolvido
pela PUC-Rio desde
meados de 2005. Evidências de recalques em estruturas
construídas nessa
região têm sido reportadas desde o final da década de 70.
O presente trabalho
apresenta resultados de estudos de laboratório realizados
visando à
caracterização do depósito argiloso e a determinação de
seus parâmetros de
compressibilidade e adensamento. Para tanto, desenvolveu-
se um programa
experimental compreendendo a caracterização físico-químico-
mineralógica de
amostras do perfil e a execução de ensaios de adensamento
edométrico e
triaxial hidrostático e anisotrópico. Os experimentos em
células edométricas
envolveram ensaios convencionais, com medida de
permeabilidade e com
determinação de compressão secundária. Aspectos de
qualidade das amostras
ensaiadas são discutidos. Os resultados obtidos
propiciaram uma estimativa do
K0 do material normalmente adensado, um entendimento do
estágio de
adensamento hoje existente e uma estimativa preliminar de
recalques que
podem ainda vir a ocorrer sob as presentes condições de
carregamento. / [en] A large research work comprising extensive field and
laboratory
investigations on a soft clay deposit located in the
Industrial Zone of Santa
Cruz, Rio de Janeiro, RJ, is being developed at PUC-Rio
since 2005.
Occurrences of settlement of structures built in this
region have been reported
since the end of the decade of 1970. This work presents
results of laboratory
studies aiming at the characterization of the soft clay
deposit and the
determination of compressibility and consolidation
parameters of the clay. The
experimental program developed comprised physical-chemical-
mineralogical
characterization of samples from the soil profile and the
execution of oedometric
consolidation tests and hydrostatic and anisotropic
triaxial tests. The
experiments in oedometric cells comprised conventional
tests and tests with
measurement of permeability and determination of secondary
compression.
Aspects of quality of the samples are highlighted. The
obtained results
propitiated an estimation of the K0 of the normally
consolidated material, an
understanding of the present stage of consolidation of the
deposit and a
preliminary assessment of settlements that may still occur
in the site under the
present loading conditions.
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[en] GEOTECHNICAL CHARACTERIZATION OF A SOFT CLAY DEPOSIT IN BAIXADA FLUMINENSE / [pt] CARACTERIZAÇÃO GEOTÉCNICA DE UM DEPÓSITO DE ARGILA MOLE DA BAIXADA FLUMINENSEMARISTANI GAMPERT SPANNENBERG 27 November 2003 (has links)
[pt] A caracterização geotécnica de um depósito de argila mole
da Baixada Fluminense foi realizada neste trabalho. Sobre
o
depósito, foi executado um extenso aterro para
implantação
da Indústria Rio Polímeros, abrangendo aproximadamente
500.000m2. Uma ampla campanha de ensaios de laboratório
foi realizada em amostras extraídas da camada de argila
mole, antes do lançamento do aterro. Este programa de
investigação incluiu ensaios de caracterização, ensaios
de
adensamento convencionais (SIC) e contínuos (CRS) e
ensaios
triaxiais drenados e não drenados. Os ensaios CRS foram
realizados sob diferentes velocidades de deformação, a
fim
de avaliar a sua influência nas características de
compressibilidade e de adensamento do material. Foi também
realizado um ensaio CRS em amostra previamente amolgada.
Os
parâmetros geotécnicos obtidos foram confrontados e
mostraram-se razoavelmente concordantes com os valores
reportados na literatura, para a Baixada Fluminense. A
influência da velocidade de deformação dos ensaios CRS foi
significativa. Entretanto, para a faixa de velocidades
adotada no presente trabalho, os parâmetros resultantes
situaram-se dentro da dispersão observada na área. O
amolgamento prévio da amostra resultou numa redução dos
parâmetros de compressibilidade e de adensamento. / [en] This work has focused on the geotechnical characterization
of a soft clay deposit in Baixada Fluminense, Rio de
Janeiro. In this area, a large embankment of approximately
500.000m2 was executed for implantation of Rio Polimeros
Industry. An extensive laboratory program was carried out
on undisturbed samples, extracted from the soft clay layer
before embankment construction. The geotechnical
investigation consisted of characterization tests,
conventional (SIC) and controlled deformation (CRS)
consolidation tests, and drained and undrained triaxial
tests. CRS tests were carried out under different
deformation velocities, in order to evaluate its influence
on compressibility parameters and on consolidation rates.
An additional CRS test was also performed using a disturbed
sample. The geotechnical parameters were analysed and
revealed a resonable agreement with the results reported in
the literature, for the Baixada Fluminense soft clay
deposit. The strain rate of CRS tests has a significant
influence on compressibility parameters. However, the
results still remain within the range of experimental data,
avaliable for the soft clay deposit of Baixada Fluminense.
It is worthwile to notice that a limited range of
velocities was used in this research. The sample
disturbance resulted in a reduction of both compressibility
parameters (cr, cc) and coefficient of consolidation.
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A Study Of Settlement Of Stone Columns By Finite Element Modeling Through Case HistoriesYardim, Cemre Harzem 01 January 2013 (has links) (PDF)
Stone column technique is mostly used to reinforce soft cohesive soils. Settlements are decreased under foundations and bearing capacity is increased. This study initially focuses on a comprehensive review of literature about stone column reinforced soils. Afterwards, numerical modeling of stone column reinforced soft clays is done. Three different cases are chosen on different foundation soils mainly soft clays. Parametric studies are done to determine influence of parameters on settlement reduction ratio under three different foundation conditions. Analyses are converted to two dimensional conditions and this conversion is also compared within the scope of this study. Settlement reduction ratio response to variation in parameters revealed similar results under three different foundation conditions.
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[en] TESTS OF FIELD AND LABORATORY IN CABRITONULLS INLET SOFT CLAY IN SALVADOR-BAHIA / [pt] ENSAIOS DE CAMPO E LABORATÓRIO NA ARGIDA MOLE DA ENSEADA DO CABRITO, SALVADOR, BAHIAHELIO MACHADO BAPTISTA 23 April 2001 (has links)
[pt] Este trabalho apresenta os resultados de uma investigação
sobre as características geotécnicas do depósito de argila
mole da enseada do Cabrito em Salvador-Bahia. Nesta área
está em curso a implantação de uma obra de urbanização,
visando o assentamento de famílias que habitavam
anteriormente no local, em casas construídas sobre
palafitas.
A determinação das propriedades geotécnicas do solo foi
feita através de ensaios de campo e de laboratório. No
campo, foram realizados ensaios de piezocone e de
dissipação de poro-pressão, além de sondagens com medida de
SPT e ensaios de palheta. Para a realização dos ensaios de
dissipação de poropressões in situ, foi desenvolvida uma
sonda piezométrica, que está apresentada neste trabalho. No
laboratório, o programa experimental constou de ensaios de
caracterização, triaxiais e de adensamento (incrementais e
contínuos). Para os ensaios de adensamento contínuos, foram
realizadas algumas modificações no equipamento
convencional, que também são descritas neste trabalho. / [en] This work presents and discusses the geotechnical
characteristics of the Cabrito's inlet
soft clay in Salvador-Bahia. On this area is in course the
implantation of an embankment,
seeking to locate families that inhabited previously in
the place, in houses built on wood piles.
The determination of the soil properties was made through
geotechnical tests of field and
laboratory. For the accomplishment of the tests of
dissipation of poropressure in situ, a
piezometer probe was developed, that is presented in this
work. For the continuos oedometer
tests, some modifications were accomplished in a
conventional cell, that are also presented in
this volume.
Finally, the obtained results of physical , of
consolidation, of deformation and of
resistance characteristics, are analyzed together, in such
a way to obtain a better
characterization of the properties of the deposit.
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[en] EXPERIMENTAL STUDY OF THE COMPRESSIBILITY AND CONSOLIDATION CHARACTERISTICS OF A SOFT CLAY / [pt] ESTUDO EXPERIMENTAL DAS CARACTERÍSTICAS DE COMPRESSIBILIDADE E ADENSAMENTO DE UMA ARGILA MOLEYGOR ALMEIDA NETTO 27 June 2007 (has links)
[pt] No presente trabalho é realizado um estudo experimental das
características de compressibilidade e adensamento de
argilas moles. Foram
realizados ensaios convencionais de adensamento (SIC) e
ensaios de
adensamento com velocidade constante de deformação (CRS) -
em diferentes
velocidades - ensaios de adensamento com uma face drenante
e ensaios
traxiais. As amostras foram remoldadas em laboratório, a
partir de uma mistura
de bentonita e caulim, na proporção de 98 : 2 em peso, e
adensadas
istoropicamente, a fim de se garantir uma melhor qualidade
quanto à
homogeneidade e isotropia do material. Os resultados são
obtidos e analisados
através das curvas típicas para os ensaios de adensamento.
São obtidos os
valores dos parâmetros de compressibilidade e de
adensamento do material. Por
fim é proposto um novo método para obtenção coeficiente de
adensamento
vertical (Cv) e feita uma análise comparativa com métodos
existentes na
literatura. / [en] In the present work it is carried out an experimental
study of the
compressibility characteristics and consolidation of a
soft clay. Standard
Incremental Consolidation (SIC) and Constant Rate of
strain (CRS) - in different
speeds - triaxiais tests and consolidation with one
drenate tests had been carried
trough. The samples had been remoulds in laboratory, from
a mixture of
bentonita and kaolin, in the ratio 98 : 2 In weight, and
confined under isotropic
conditions, in order to guarantee one better quality how
much to the homogeneity
and isotropy of the material. The results are gotten and
analyzed through the
typical curves for consolidation tests. The values of the
parameters of
compressibility and consolidation of the material are
gotten. Finally a new method
for attainment of the vertical consolidation coefficient
(Cv) and made a
comparative analysis with existing methods in literature
is considered.
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Numerical Analysis of a Large-Scale Levee on Soft Soil Deposits Using Two-Phase Finite Deformation Theory / 2相系有限変形理論を用いた軟弱地盤上の大規模堤防の数値解析MIRJALILI, Mojtaba 24 September 2010 (has links)
Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第15646号 / 工博第3304号 / 新制||工||1499(附属図書館) / 28183 / 京都大学大学院工学研究科社会基盤工学専攻 / (主査)教授 岡 二三生, 教授 勝見 武, 准教授 木元 小百合 / 学位規則第4条第1項該当
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