scholarly journals Technical Notoe: Prediction of Static Liquefaction by Nor Sand Constitutive Model

2015 ◽  
Vol 36 (3) ◽  
pp. 75-83
Author(s):  
Krzysztof Sternik
Keyword(s):  
Constitutive Model ◽  
Critical State ◽  
Soil Mechanics ◽  
State Parameter ◽  
Short Description ◽  
Flow Rule ◽  
Saturated Sand ◽  
Hardening Law ◽  
Static Liquefaction ◽  
Associated Flow Rule

Abstract The paper gives a short description of unstable behaviour of saturated sand under undrained monotonic loading. Constitutive model Nor Sand capable to describe static liquefaction is presented. The model is based on critical state soil mechanics and assumes associated flow rule. Hardening law incorporates the state parameter proposed earlier by Been and Jefferies. Results of numerical simulations of undrained element tests have been presented and discussed.

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.

scholarly journals A Thermodynamic Constitutive Model for Saturated Sand

Entropy ◽  
2019 ◽  
Vol 21 (2) ◽  
pp. 136
Author(s):  
Shize Xiao ◽  
Xiaohui Cheng ◽  
Zhou Yang
Keyword(s):  
Constitutive Model ◽  
Soil Mechanics ◽  
Constitutive Models ◽  
Yield Function ◽  
Flow Rule ◽  
Saturated Sand ◽  
Coupling Energy ◽  
Dissipative Mechanism ◽  
Nonlinear Elastic ◽  
Undrained Shear

This paper establishes a non-equilibrium thermodynamic constitutive model that can predict the undrained shear behavior of saturated sand. Starting from the basic laws of thermodynamics, the model does not require the classical concepts in elasto-plastic models, such as the yield function, the flow rule, and the hardening rule. It is also different from the existing thermodynamic constitutive models in soil mechanics literatures. The model does not use a complex nonlinear elastic potential as usually and introduces a coupling energy dissipative mechanism between the viscosity and elasticity relaxation, which is essential in granular materials. Then this model was used to simulate the undrained shear test of Toyoura sand. The model can predict the critical state, dilatancy-contraction and hardening-softening characteristics of sand during undrained triaxial shearing.

scholarly journals Finite Element Simulations of an Elasto-Viscoplastic Model for Clay

Geosciences ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 145 ◽  
Author(s):  
Mohammad N. Islam ◽  
Carthigesu T. Gnanendran ◽  
Mehrdad Massoudi
Keyword(s):  
Finite Element ◽  
San Francisco ◽  
Critical State ◽  
Soil Mechanics ◽  
Flow Rule ◽  
Compression Index ◽  
Mechanics Model ◽  
Associated Flow Rule ◽  
Marine Deposit ◽  
Good Agreement

In this paper, we develop an elasto-viscoplastic (EVP) model for clay using the non-associated flow rule. This is accomplished by using a modified form of the Perzyna’s overstressed EVP theory, the critical state soil mechanics, and the multi-surface theory. The new model includes six parameters, five of which are identical to those in the critical state soil mechanics model. The other parameter is the generalized nonlinear secondary compression index. The EVP model was implemented in a nonlinear coupled consolidated code using a finite-element numerical algorithm (AFENA). We then tested the model for different clays, such as the Osaka clay, the San Francisco Bay Mud clay, the Kaolin clay, and the Hong Kong Marine Deposit clay. The numerical results show good agreement with the experimental data.

scholarly journals A state parameter-based thermomechanical constitutive model for fine-grained saturated soils

2020 ◽  
Author(s):  
Qi-Yin Zhu ◽  
Pei-Zhi Zhuang ◽  
Zhen-Yu Yin ◽  
Hai-Sui Yu
Keyword(s):  
Constitutive Model ◽  
Triaxial Compression ◽  
Boundary Surface ◽  
State Parameter ◽  
Flow Rule ◽  
Fine Grained ◽  
Hardening Law ◽  
Heating And Cooling ◽  
Thermomechanical Behaviour ◽  
Spacing Ratio

This paper presents a two-surface constitutive model for describing thermomechanical behaviour of saturated fine-grained soils at both normally consolidated and overconsolidated states. A thermal-dependent stress ratio-state parameter relation is adopted to account for the effects of temperature on the shape of the state boundary surface (SBS) of soils. In the model, both the size and the shape of the SBS are allowed to vary with temperature, which is evidenced by thermal variation of the mechanical yield loci and the shifts of the normal consolidation line (NCL) and the critical state line (CSL) upon heating and/or cooling. A thermal yield surface is added for modelling the isotropic thermal deformation of soils more accurately, in particular at overconsolidated states. The mechanical and thermal yield mechanisms are coupled by the temperature-dependent preconsolidation pressure which is controlled by a volumetric hardening law. Based on experimental observations, a nonlinear relationship between the spacing ratio and temperature changes is defined and a simple thermal dependent non-associated flow rule is proposed. The model is validated against some selected experimental results of several soils tested under various mechanical and thermal paths such as drained isotropic heating and cooling, drained and undrained triaxial compression at non-isothermal conditions.

A model for static liquefaction in triaxial compression and extension

2002 ◽  
Vol 39 (6) ◽  
pp. 1243-1253 ◽  
Author(s):  
N Boukpeti ◽  
Z Mróz ◽  
A Drescher
Keyword(s):  
Constitutive Model ◽  
Static Loading ◽  
Yield Curve ◽  
Triaxial Compression ◽  
Triaxial Tests ◽  
Isotropic Hardening ◽  
Flow Rule ◽  
Static Liquefaction ◽  
Different Response ◽  
Associated Flow Rule

The response of the elastoplastic refined Superior sand constitutive model in undrained triaxial compression and extension tests is presented. The model is aimed at realistic simulation of liquefaction occurring in loose, saturated, granular materials under monotonic static loading. The yield surface introduced previously in the original Superior sand model is modified, and a non-associated flow rule is used. The isotropic hardening–softening is related to plastic deformation and distance to a reference yield curve. The refined model accounts for the different response of materials with different deposition densities. The model prediction of undrained triaxial compression and extension tests is compared with experimental results. The higher tendency for liquefaction response in extension is well described. Instability and phase-transformation states also are discussed, and the energy of liquefaction is quantified.Key words: static liquefaction, constitutive model, triaxial tests, liquefaction energy.

Effects of fines on liquefaction behaviour in well-graded materials

2017 ◽  
Vol 54 (10) ◽  
pp. 1460-1471 ◽  
Author(s):  
Katherine A. Kwa ◽  
David W. Airey
Keyword(s):  
Critical State ◽  
Soil Mechanics ◽  
State Parameter ◽  
Triaxial Tests ◽  
Particle Sizes ◽  
Graded Materials ◽  
Fines Content ◽  
Cyclic Resistance ◽  
Wide Range ◽  
Soil Behaviour

This study uses a critical state soil mechanics perspective to understand the mechanics behind the liquefaction of metallic ores during transport by ship. These metallic ores are transported at relatively low densities and have variable gradings containing a wide range of particle sizes and fines contents. The effect of the fines content on the location of the critical state line (CSL) and the cyclic liquefaction behaviour of well-graded materials was investigated by performing saturated, standard drained and undrained monotonic and compression-only cyclic triaxial tests. Samples were prepared at four different gradings containing particle sizes from 9.5 mm to 2 μm with fines (<75 μm) contents of 18%, 28%, 40%, and 60%. In the e versus log[Formula: see text] plane, where e is void ratio and [Formula: see text] is mean effective stress, the CSLs shifted upwards approximately parallel to one another as the fines content was increased. Transitional soil behaviour was observed in samples containing 28%, 40%, and 60% fines. A sample’s cyclic resistance to liquefaction depended on a combination of its density and state parameter, which were both related to the fines content. Samples with the same densities were more resistant to cyclic failure if they contained higher fines contents. The state parameter provided a useful prediction for general behavioural trends of all fines contents studied.

Descriptions of Reversed Yielding in Internally Pressurized Tubes

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Sergei Alexandrov ◽  
Woncheol Jeong ◽  
Kwansoo Chung
Keyword(s):  
Yield Criterion ◽  
Numerical Technique ◽  
Kinematic Hardening ◽  
Material Model ◽  
Flow Rule ◽  
Hardening Material ◽  
Hardening Law ◽  
Solving Equations ◽  
Associated Flow Rule ◽  
Reversed Deformation

Using Tresca's yield criterion and its associated flow rule, solutions are obtained for the stresses and strains when a thick-walled tube is subject to internal pressure and subsequent unloading. A bilinear hardening material model in which allowances are made for a Bauschinger effect is adopted. A variable elastic range and different rates under forward and reversed deformation are assumed. Prager's translation law is obtained as a particular case. The solutions are practically analytic. However, a numerical technique is necessary to solve transcendental equations. Conditions are expressed for which the release is purely elastic and elastic–plastic. The importance of verifying conditions under which the Tresca theory is valid is emphasized. Possible numerical difficulties with solving equations that express these conditions are highlighted. The effect of kinematic hardening law on the validity of the solutions found is demonstrated.

A non-quadratic pressure-sensitive constitutive model under non-associated flow rule with anisotropic hardening: Modeling and validation

2020 ◽  
Vol 135 ◽  
pp. 102808 ◽  
Author(s):  
Yong Hou ◽  
Junying Min ◽  
Thomas B. Stoughton ◽  
Jianping Lin ◽  
John E. Carsley ◽  
...  
Keyword(s):  
Constitutive Model ◽  
Flow Rule ◽  
Anisotropic Hardening ◽  
Pressure Sensitive ◽  
Associated Flow Rule

Modified state parameter for characterizing static liquefaction of sand with fines

2009 ◽  
Vol 46 (3) ◽  
pp. 281-295 ◽  
Author(s):  
D. C. Bobei ◽  
S. R. Lo ◽  
D. Wanatowski ◽  
C. T. Gnanendran ◽  
M. M. Rahman
Keyword(s):  
Critical State ◽  
Volumetric Strain ◽  
State Parameter ◽  
Confining Pressure ◽  
Log P ◽  
Test Results ◽  
Static Liquefaction ◽  
Isotropic Consolidation ◽  
Failure Line ◽  
Soil Behaviour

An experimental study was carried out to investigate the static liquefaction behaviour of sand with a small amount of plastic and nonplastic fines. Five series of tests were conducted in drained and undrained conditions. The drained test results indicate not only that the failure line coincides with the critical state, but also that the development of volumetric strain during shearing was not sensitive to the initial confining pressure. In both isotropically and anisotropically consolidated undrained tests, a so-called “reverse behaviour” was consistently observed. The results were also interpreted in the critical state framework. The critical and steady state (CS/SS) data were found to trace along the same curve in e–log( p′) space, irrespective of the stress history and effective stress paths. A comparison between the isotropic consolidation line (ICL) and critical state (CS) curve showed that a small amount of fines can significantly change the shape and position of the ICL relative to the CS curve. Furthermore, the soil behaviour manifested in both drained and undrained shearing led to the development of a modified state parameter.

Influence of state and compressibility on liquefied strength of sands

2013 ◽  
Vol 50 (10) ◽  
pp. 1067-1076 ◽  
Author(s):  
Abouzar Sadrekarimi
Keyword(s):  
Shear Strength ◽  
Critical State ◽  
Soil Mechanics ◽  
State Parameter ◽  
Test Results ◽  
Confining Stress ◽  
Stress Variation ◽  
Laboratory Test Results ◽  
Flow Failure ◽  
Underlying Mechanisms

Critical-state soil mechanics is a useful framework to understand sand behavior. In this paper, a relationship is developed for estimating undrained critical shear strength of sands based on the critical-state framework. The application of this relationship is demonstrated by comparison with laboratory test results and sand liquefied strength from field liquefaction flow failure case histories. Using this relationship, the effects of effective stress variation and density on undrained critical shear strength are studied for different combinations of critical-state line parameters corresponding to several reference sands. The parametric study indicates that depending on sand void ratio, undrained critical shear strength may increase, remain the same or decrease as sand shearing–compressibility (represented by the slope of the critical-state line) increases. The underlying mechanisms of field failures in dense sands and reverse behavior of compressible sands are explained through this relationship. It is suggested that the critical-state parameter alone is insufficient for describing the behavior of liquefiable sands and sand shearing–compressibility should be also taken into account for estimating undrained shear strength corresponding to the changes in density and effective confining stress.

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