Unied modeling of three-dimensional soil behavior based on the tij concept

2012 ◽  
pp. 120-155
Keyword(s):  
Three Dimensional ◽  
Soil Behavior ◽  
Behavior Based

Utilisation d'équations constitutives du comportement du sol pour la prédiction d'essais triaxiaux sur des granulats calcaires

1995 ◽  
Vol 32 (1) ◽  
pp. 156-166 ◽  
Author(s):  
M. Jrad ◽  
F. Masrouri ◽  
J. Monnet
Keyword(s):  
Plastic Flow ◽  
Three Dimensional ◽  
Yield Function ◽  
Cohesionless Soil ◽  
Triaxial Tests ◽  
Soil Behavior ◽  
Limestone Aggregate ◽  
Element Computation ◽  
Internal Angle ◽  
The Relationship

This paper analyses the three-dimensional consolidation and shear behavior of cohesionless soil. It is divided in two parts: In the first part, the law of soil behavior is described. So far, the soil was assumed to be elastoplastic with associated plastic flow and stress hardening behavior. In this study, a new version of the Chaffois–Monnet law presents the yield function during consolidation and shearing in a single energy equation which avoids numerical errors due to the iterative process of the finite element computation, and numerical gap between consolidation and shearing. This new model uses only eight parameters with geotechnical significance. In the second part of this study, the results of the model are compared with experimental data from consolidated drained triaxial tests on three types of limestone aggregates. The validity of the model is finally discussed, and the relationship between the internal angle of friction and the mean stress is shown. Key words : behavior law, elastoplastic, associated, plastic flow, limestone aggregate, triaxial test.

Interaction Deep Excavation – Adjacent Structure: Numerical Two and Three Dimensional Modeling

2011 ◽  
Vol 324 ◽  
pp. 344-347 ◽  
Author(s):  
M. Abdallah ◽  
Fadi Hage Chehade ◽  
Walid Chehade ◽  
A. Fawaz
Keyword(s):  
Soil Structure ◽  
Three Dimensional ◽  
Material Structure ◽  
Deep Excavation ◽  
The Finite Element Method ◽  
Soil Behavior ◽  
Three Dimensional Modeling ◽  
Dimensional Modeling ◽  
Adjacent Structure ◽  
Comparison Of The Results

Urban development often requires the construction of deep excavations near to buildings or other structures. We have to study complex material structure interactions where we should take into consideration several particularities. In this paper, we perform a numerical modeling with the finite element method, using PLAXIS software, of the interaction deep excavation-diaphragm wall-soil-structure in the case of non linear soil behavior. We focus our study on a comparison of the results given respectively by two and three dimensional modelings. This allows us to give some recommendations concerning the validity of twodimensional study. We perform a parametric study according to the initial loading on the structure and the struts number.

Consistent Three-Dimensional Elasto-Plastic Model to Study Unsaturated Soil Behavior with Considerations of Coupled Hydro-Mechanical Hysteresis

2021 ◽  
pp. 036119812110022
Author(s):  
Beshoy Riad ◽  
Xiong Zhang
Keyword(s):  
Unsaturated Soil ◽  
Yield Curve ◽  
Three Dimensional ◽  
Degree Of Saturation ◽  
Smooth Transition ◽  
Soil Behavior ◽  
Plastic Model ◽  
Mechanical Coupling ◽  
Mechanical Hysteresis ◽  
Characteristic Features

This paper presents a consistent three-dimensional elasto-plastic model to study unsaturated soil behavior with consideration of coupled hydro-mechanical hysteresis. The model was first formulated under isotropic conditions with special consideration to the non-linearity of the hydraulic behavior. Only one yield curve is used to represent the yielding of both mechanical and hydraulic behaviors (i.e., the occurrence of plastic water content changes and mechanical strains). Later, the model is extended to general three-dimensional stress conditions. It was formulated in a way that a smooth transition between the saturated and unsaturated soil states is guaranteed. The model provides consistent predictions for different soil phases that is considered a significant limitation in many existing models. One of the characteristic features of the proposed model is the ability to represent the hydro-mechanical coupling during shearing. Moreover, the model is able to represent the degree of saturation increase or decrease during shearing that is closely related to the soil’s contractive or dilative behavior, respectively. The model is validated through the prediction of several hydro-mechanical behavioral features. The paper also compares the model predictions with published experimental results performed under different loading conditions. The response of the model is satisfactory in relation to both mechanical and hydraulic behaviors.

scholarly journals BACK ANALYSIS OF OSTERBERG-CELL PILE LOAD TEST BY MEANS OF THREE-DIMENSIONAL GEOTECHNICAL MODELING

2021 ◽  
Vol 30 (3) ◽  
Author(s):  
Szilárd Kanizsár
Keyword(s):  
Construction Projects ◽  
Three Dimensional ◽  
Back Analysis ◽  
Field Tests ◽  
Small Strain ◽  
Load Test ◽  
Soil Behavior ◽  
Load Tests ◽  
Pile Load Test ◽  
Pile Load Tests

In 3D geotechnical modelling it is essential for the realistic simulation of soil behavior that the parameters of the hardening soil with small strain constitutive model are specified appropriately. The possibility of deriving these parameters for very stiff cohesive soils similar to the so called Kiscell clay that has a significant role in deep construction projects in Budapest, from laboratory and field tests is rather limited. The results of the pile load test completed for the MOL Campus high-rise building project proved to be useful data source. The article presents the circumstances of the quoted Osterberg-cell pile load tests and the modelling of the pile performed by the above-mentioned soil model. The parameters specified on the basis of laboratory tests - and in absence of those based on literature - data can be fine-tuned by approaching the load test results.

scholarly journals Three-Dimensional Stability Analysis of a Homogeneous Slope Reinforced with Micropiles

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Shu-Wei Sun ◽  
Wei Wang ◽  
Fu Zhao
Keyword(s):  
Slip Surface ◽  
Three Dimensional ◽  
Failure Surface ◽  
Embedment Depth ◽  
Critical Slip Surface ◽  
Soil Behavior ◽  
Nonlinear Method ◽  
Strength Reduction Technique ◽  
The Stability ◽  
Coulomb Criterion

Micropiles are widely used to reinforce slopes due to their successful performance and fast construction. In this study, a simple nonlinear method is proposed to analyze the stability of a homogeneous slope reinforced with micropiles. This method is based on shear strength reduction technique, in which the soil behavior is described using the nonassociated Mohr-Coulomb criterion and micropiles are modeled as 3D pile elements. A series of slope stability analyses is performed to investigate the coupled mechanism of micropile system, and the optimum of pile position, depth of embedment, and length of truncation are analyzed. Results show that the position of micropile system plays an important role not only in the calculation of the safety factor, but also in locating the failure surface, which demonstrates the dominating coupled effect exists between micropiles and slope. The critical embedment depth of the micropile is about 2 times the length of micropile above the critical slip surface, and the micropiles flexure rather than rotation becomes increasingly prevalent as the depth of micropiles embedment increases. Truncation of micropiles may improve the capacity of the micropile system, and the largest truncation length of micropile is about 1/4 depth of critical slip surface in this study.

Three-dimensional analysis of unanticipated behavior of a deep excavation

2018 ◽  
Vol 55 (11) ◽  
pp. 1647-1656 ◽  
Author(s):  
R. Kerry Rowe ◽  
Ahmed Mabrouk
Keyword(s):  
Three Dimensional ◽  
Low Permeability ◽  
Deep Excavation ◽  
Soil Behavior ◽  
Dissolved Gas ◽  
Element Analysis ◽  
Clayey Silt ◽  
Bedrock Aquifer ◽  
Weak Zones ◽  
Lateral Deformations

A three-dimensional (3D) effective stress finite element analysis, modified to account for hydrofracturing and gassy soil behavior, is used to examine the potential for the venting of water and gas from a bedrock aquifer and through 13–14 m of low permeability clayey silt between the base of the excavation and the bedrock following excavation to about 24 m in an approximately 40 m thick clayey silt deposit. The clayey deposit contained sand lenses with dissolved gas. The analysis predicts that the exsolution of this dissolved gas, caused by a reduction in total stress due to the excavation, results in liquefaction of the sand in the lenses and consequent lateral deformations of the side slopes. The analysis predicts hydrofracturing through the remaining clayey silt when the excavation reaches its final depth and this explains the venting of water and gas from the underlying aquifer that was observed above a local bedrock high. The presence of gassy sand lenses created weak zones within the clayey deposit that influenced the path of the hydrofracturing. However, the analyses suggest that, for the depth of excavation and bedrock elevation examined, hydrofracturing and subsequent venting would have occurred even if there had been no sand lenses.

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