scholarly journals Validation of a simple hypoplastic constitutive model for overconsolidated clays

2021 ◽  
Author(s):  
shun wang ◽  
Wei Wu
Keyword(s):  
Laboratory Tests ◽  
Constitutive Models ◽  
Standard Laboratory ◽  
Hypoplastic Model ◽  
Proposed Model ◽  
Modified Cam Clay ◽  
Overconsolidated Clays ◽  
Hypoplastic Constitutive Model ◽  
Comparison With Experiments ◽  
Cam Clay

Hypoplastic constitutive models are able to describe history dependence using a single nonlinear tensorial function with a set of parameters. A hypoplastic model including a structure tensor for consolidation history was introduced in our previous paper (Wang and Wu in Acta Geotechnica, 2020, https://doi.org/10.1007/s11440-020-01000-z). The present paper focuses mainly on the model validation with experiments. This model is as simple as the modified Cam Clay model but with better performance. The model requires five parameters, which are easy to calibrate from standard laboratory tests. In particular, the model is capable of capturing the unloading behavior without introducing loading criteria. Numerical simulations of element tests and comparison with experiments show that the proposed model is able to reproduce the salient features of normally consolidated and overconsolidated clays.

scholarly journals Validation of a simple hypoplastic constitutive model for overconsolidated clays

2020 ◽  
Author(s):  
Shun Wang ◽  
Wei Wu
Keyword(s):  
Laboratory Tests ◽  
Constitutive Models ◽  
Standard Laboratory ◽  
Hypoplastic Model ◽  
Proposed Model ◽  
Modified Cam Clay ◽  
Overconsolidated Clays ◽  
Hypoplastic Constitutive Model ◽  
Comparison With Experiments ◽  
Cam Clay

AbstractHypoplastic constitutive models are able to describe history dependence using a single nonlinear tensorial function with a set of parameters. A hypoplastic model including a structure tensor for consolidation history was introduced in our previous paper (Wang and Wu in Acta Geotechnica, 2020, 10.1007/s11440-020-01000-z). The present paper focuses mainly on the model validation with experiments. This model is as simple as the modified Cam Clay model but with better performance. The model requires five parameters, which are easy to calibrate from standard laboratory tests. In particular, the model is capable of capturing the unloading behavior without introducing loading criteria. Numerical simulations of element tests and comparison with experiments show that the proposed model is able to reproduce the salient features of normally consolidated and overconsolidated clays.

scholarly journals A simple hypoplastic model for overconsolidated clays

2021 ◽  
Author(s):  
shun wang ◽  
Wei Wu
Keyword(s):  
Constitutive Model ◽  
Structure Tensor ◽  
History Dependence ◽  
Hypoplastic Model ◽  
Clay Model ◽  
Modified Cam Clay ◽  
Overconsolidated Clays ◽  
Independent Parameters ◽  
Hypoplastic Constitutive Model ◽  
Cam Clay

This paper presents a simple hypoplastic constitutive model for overconsolidated clays. The model needs five independent parameters and is as simple as the modified Cam Clay model but with better performance. A structure tensor is introduced to account for the history dependence. Simulations of various elementary tests show that the model is capable of capturing the salient behavior of overconsolidated clays.

scholarly journals Critical state constitutive models and shear loading of overconsolidated clays with deviatoric hardening

2019 ◽  
Vol 41 (4) ◽  
pp. 247-262
Author(s):  
Sara Rachdi ◽  
Emad Jahangir ◽  
Michel Tijani ◽  
Jean-François Serratrice
Keyword(s):  
Critical State ◽  
Constitutive Models ◽  
Shear Loading ◽  
Triaxial Tests ◽  
Soil Response ◽  
Proposed Model ◽  
Overconsolidated Clays ◽  
Mean Pressure ◽  
State Models ◽  
Cam Clay

AbstractThis paper presents an enhanced constitutive model integrating deviatoric hardening with a modified yield surface for overconsolidated clayey soils in a general framework of Cam-clay type models. Its performance was assessed with the simulation of drained and undrained triaxial tests on three clays at different consolidation states in comparison to two critical state models. The proposed model satisfactorily estimates the shear resistance, while capturing the smooth nonlinearity of the soil response.Shear triaxial tests at constant mean pressure were performed on an overconsolidated marl to study the shear response. Their simulation attests the importance of deviatoric hardening integration.

scholarly journals Study on arching effect in the embankment over pile - reinforced soft soil

2020 ◽  
Vol 61 (HTCS6) ◽  
pp. 19-25
Author(s):  
Hung Van Pham ◽  
Huy Quang Dang ◽  
Lam Phuc Dao ◽  
Long Khac Nguyen ◽  
Keyword(s):  
Stress Reduction ◽  
Soft Soil ◽  
Constitutive Models ◽  
Pile Group ◽  
3D Numerical Modeling ◽  
Soil Arching ◽  
Modified Cam Clay ◽  
Stress Concentration Ratio ◽  
Pile Group Effect ◽  
Cam Clay

The paper employes 3D numerical modeling to analyze the soil arching mechanism within embankment by FLAC3D code, based on the finite difference method (FDM). To consider the pile group effect, the 3D mesh of four pile has been created. Related to the constitutive models, the embankment is used Mohr - Coulomb model, the soft soil is represented by modified Cam - clay model, and footing and piles are employed by elasticity model. The numerical results focus on the soil arching phenomena in terms of stress distribution on piles and soft soil, the stress concentration ratio and the stress reduction ratio. Additionally, the axial force along pile and the settlements of embankment, soft soil and pile are studied.

A hypoplastic constitutive model for clays with meta-stable structure

2007 ◽  
Vol 44 (3) ◽  
pp. 363-375 ◽  
Author(s):  
David Mašín
Keyword(s):  
Kinematic Hardening ◽  
Constitutive Relations ◽  
Calibration Procedure ◽  
Stable Structure ◽  
Hypoplastic Model ◽  
Practical Applications ◽  
Soft Clays ◽  
Proposed Model ◽  
Nonlinear Character ◽  
Hypoplastic Constitutive Model

A new hypoplastic model for clays with meta-stable structure is presented in this paper. A new method for incorporation of structure effects into hypoplastic models based on the modification of barotropy and pyknotropy factors is proposed and applied to an existing hypoplastic model for reconstituted clays. The new model is characterized by a simple calibration procedure and a small number of parameters. This makes the model particularly suitable for practical applications. The model is evaluated using experimental data for two natural soft clays. Thanks to the incrementally nonlinear character of the hypoplastic equation, the proposed model predicts behaviour of overconsolidated clays comparably to advanced kinematic hardening elastoplastic models.Key words: constitutive relations, hypoplasticity, clays, structure of soils.

A Simple Constitutive Model for Overconsolidated Clays

2011 ◽  
Vol 243-249 ◽  
pp. 2283-2286
Author(s):  
Yang Liu ◽  
Xian De Zhu ◽  
Zhi Gong
Keyword(s):  
Constitutive Model ◽  
Soil Mechanics ◽  
Flow Rule ◽  
Hardening Law ◽  
Proposed Model ◽  
Overconsolidated Clays ◽  
Strain Relationship ◽  
As Stress ◽  
Associated Flow Rule ◽  
Cam Clay

In the framework of critical state soil mechanics, a simple constitutive model for overconsolidated clays is proposed based on subloading surface and normal consolidation yield surface. A more rational hardening law is used to describe the change between subloading surface and the normal consolidation surface with plastic deformation and an associated flow rule is adopted. The model can describe many characteristics of overcaonsolidated clays, such as stress-strain relationship, strain hardening and softening, and stress dilatancy. Compared with the Cam-clay model, two more parameters are required which represents specific physical meanings. Numerical simulation is compared with data from triaxial drained compression test, indicating that the proposed model can rationally describe overconsolidated properties.

A structured Cam Clay model

2002 ◽  
Vol 39 (6) ◽  
pp. 1313-1332 ◽  
Author(s):  
M D Liu ◽  
J P Carter
Keyword(s):  
Parametric Study ◽  
Soil Structure ◽  
Constitutive Relations ◽  
Calcareous Soils ◽  
New Model ◽  
Clay Model ◽  
Proposed Model ◽  
Modified Cam Clay ◽  
Structured Soils ◽  
Cam Clay

A theoretical study of the behaviour of structured soil is presented. A new model, referred to as the Structured Cam Clay model, is formulated by introducing the influence of soil structure into the Modified Cam Clay model. The proposed model is hierarchical, i.e., it is identical to the Modified Cam Clay soil model if a soil has no structure or if its structure is removed by loading. Three new parameters describing the effects of soil structure are introduced, and the results of a parametric study are also presented. The proposed model has been used to predict the behaviour of structured soils in both compression and shearing tests. By making comparisons of predictions with experimental data and by conducting the parametric study it is demonstrated that the new model provides satisfactory qualitative and quantitative modelling of many important features of the behaviour of structured soils.Key words: calcareous soils, clays, fabric, structure, constitutive relations, plasticity.

Unified Three-Dimensional Revision of Modified Cam Clay Model

2007 ◽  
Vol 340-341 ◽  
pp. 1267-1272
Author(s):  
Hang Zhou Li ◽  
Hong Jian Liao ◽  
Kyoji Sassa ◽  
Gong Hui Wang
Keyword(s):  
Three Dimensional ◽  
Yield Function ◽  
Triaxial Tests ◽  
Strength Theory ◽  
Unified Strength Theory ◽  
True Triaxial ◽  
Proposed Model ◽  
Modified Cam Clay ◽  
Stress States ◽  
Cam Clay

According to unified strength parameters obtained from unified strength theory, the slope of critical state line is modified to reflect critical states of different geomaterials under general stress states. Yield function that can consider the effect of the third deviatoricic invariant is proposed, and an elasto-plastic constitutive model is established by adopting non-associated flow rules; furthermore, methods of overcoming singular points on the yield surface are discussed. The proposed model is verified by true triaxial tests of clay, and results show that the model can well predict stress-strain relationships.

scholarly journals Finite element analyses of energy piles using different constitutive models

2020 ◽  
Vol 205 ◽  
pp. 05013
Author(s):  
Chiara Iodice ◽  
Raffaele Di Laora ◽  
Alessandro Mandolini
Keyword(s):  
Finite Element ◽  
Constitutive Models ◽  
Single Pile ◽  
Finite Element Analyses ◽  
Energy Pile ◽  
State Of Stress ◽  
Modified Cam Clay ◽  
Energy Piles ◽  
Fully Coupled ◽  
Cam Clay

Energy piles are foundation elements having the double scope of transferring structural loads from the structure to the ground and of exchanging heat with the surrounding soil. It follows that pile state of stress and settlement are altered by the time-dependent temperature change in both pile and soil. This work is aimed at investigating the effect of thermal cycles on the behaviour of a single energy pile. To this end, fully coupled thermo-hydro-mechanical analyses have been carried out using the Finite Element code ABAQUS. The single pile is installed in a normally consolidated clay behaving according to different constitutive models involving Mohr-Coulomb, Modified Cam Clay and Hypoplastic. The latter is employed with and without the thermal formulation capable of accounting for the thermal collapse of NC clays during heating. A single free-head pile is considered and the results are presented in terms of pile axial force and settlement developed cycle by cycle.

Evaluation of Plate Anchors Capacity in Saturated Soils Using Different Constitutive Models

2014 ◽  
Author(s):  
Zahra Aghazadeh ◽  
M. S. Rahman ◽  
M. A. Gabr
Keyword(s):  
Soft Soil ◽  
Constitutive Models ◽  
Control Approach ◽  
Pull Out ◽  
Saturated Clay ◽  
Element Simulation ◽  
Modified Cam Clay ◽  
Plate Anchor ◽  
Plate Anchors ◽  
Cam Clay

Evaluation of the uplift capacity of plate anchors in saturated clay is an important aspect in offshore anchoring of various structures. In most of the literature reviewed, a constitutive model such as Tresca or Mohr-Coulomb has been used in analyses. There exists a need to study the anchors’ pull out capacity using other advanced soil models and discern differences in results. This study presents the results of finite element simulation of a rectangular or circular plate anchor in saturated clay. The capacity factors (Nc) of the plate are assessed through the application of displacement control approach and the results are compared to the lower bound solution as well as to data obtained from similar studies available in the literature. In addition to Mohr-Coulomb model, two other constitutive models are used to represent the soil deformation. These are Modified Cam-Clay, and Soft Soil models. Undrained effective stress analyses are conducted using the computer program PLAXIS. A series of analyses using different embedment depths are performed for all three constitutive models. Results as Nq value from the three constitutive models are presented and discussed.

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