Formulation of a three-dimensional constitutive model for unsaturated soils incorporating mechanical-water retention couplings

2013 ◽  
Vol 37 (17) ◽  
pp. 3008-3035 ◽  
Author(s):  
Martí Lloret-Cabot ◽  
Marcelo Sánchez ◽  
Simon J. Wheeler
Keyword(s):  
Constitutive Model ◽  
Unsaturated Soils ◽  
Water Retention ◽  
Three Dimensional

scholarly journals Elastoplastic Model and Three-Dimensional Method for Unsaturated Soils

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Jinjin Fang ◽  
Yixin Feng
Keyword(s):  
Constitutive Model ◽  
Unsaturated Soils ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Degree Of Saturation ◽  
Triaxial Tests ◽  
Model Parameters ◽  
Elastoplastic Model ◽  
True Triaxial ◽  
Elastoplastic Constitutive Model

This paper proposed a new elastoplastic constitutive model to predict the deformation and strength behaviour of unsaturated soils. Applying the modified Cambridge model as a generalization, the degree of saturation is introduced into the elastoplastic model of unsaturated soil. Under the condition of ensuring that the model parameters are unchanged, the model is transformed into three dimensions based on the SMP criterion transformation stress method. Enhanced modified van Genuchten model under true triaxial conditions is also proposed in this paper to describe hydromechanical behaviours of unsaturated soils. The proposed constitutive model can capture the observed mechanical and hydraulic behaviours. Then, the model is validated via equal p and equal b value true triaxial tests, and the results show that a reasonable agreement can be obtained.

scholarly journals Alternative derivation of the higher-order constitutive model for six-parameter elastic shells

2021 ◽  
Vol 72 (2) ◽  
Author(s):  
Mircea Bîrsan
Keyword(s):  
Energy Density ◽  
Constitutive Model ◽  
Strain Energy Density ◽  
Strain Energy ◽  
Shell Theory ◽  
Constitutive Relations ◽  
Three Dimensional ◽  
Classical Shell Theory ◽  
Three Dimensional Elasticity ◽  
General Method

AbstractIn this paper, we present a general method to derive the explicit constitutive relations for isotropic elastic 6-parameter shells made from a Cosserat material. The dimensional reduction procedure extends the methods of the classical shell theory to the case of Cosserat shells. Starting from the three-dimensional Cosserat parent model, we perform the integration over the thickness and obtain a consistent shell model of order $$ O(h^5) $$ O ( h 5 ) with respect to the shell thickness h. We derive the explicit form of the strain energy density for 6-parameter (Cosserat) shells, in which the constitutive coefficients are expressed in terms of the three-dimensional elasticity constants and depend on the initial curvature of the shell. The obtained form of the shell strain energy density is compared with other previous variants from the literature, and the advantages of our constitutive model are discussed.

Progressive failure analysis of scarf-repaired composite laminate based on damage constitutive model

2016 ◽  
Vol 233 (2) ◽  
pp. 180-188 ◽  
Author(s):  
Qiuyi Shen ◽  
Zhenghao Zhu ◽  
Yi Liu
Keyword(s):  
Finite Element ◽  
Constitutive Model ◽  
Composite Laminate ◽  
Damage Mechanics ◽  
Cohesive Zone Model ◽  
Load Capacity ◽  
Three Dimensional ◽  
Zone Model ◽  
State Variables ◽  
Element Analysis

A three-dimensional finite element model for scarf-repaired composite laminate was established on continuum damage model to predict the load capacity under tensile loading. The mixed-mode cohesive zone model was adopted to the debonding behavior analysis of adhesive. Damage condition and failure of laminates and adhesive were subsequently addressed. A three-dimensional bilinear constitutive model was developed for composite materials based on damage mechanics and applied to damage evolution and loading capacity analyses by quantifying damage level through damage state variables. The numerical analyses were implemented with ABAQUS finite element analysis by coding the constitutive model into material subroutine VUMAT. Good agreement between the numerical and experimental results shows the accuracy and adaptability of the model.

Study on the generalized k-Hilfer–Prabhakar fractional viscoelastic–plastic model

2021 ◽  
pp. 108128652110258
Author(s):  
Yi-Ying Feng ◽  
Xiao-Jun Yang ◽  
Jian-Gen Liu ◽  
Zhan-Qing Chen
Keyword(s):  
Constitutive Model ◽  
Three Dimensional ◽  
Sensitivity Analyses ◽  
Creep Process ◽  
Fractional Operator ◽  
Modified Model ◽  
Proposed Model ◽  
Accelerated Creep ◽  
The Laplace Transform ◽  
Classical Models

The general fractional operator shows its great predominance in the construction of constitutive model owing to its agility in choosing the embedded parameters. A generalized fractional viscoelastic–plastic constitutive model with the sense of the k-Hilfer–Prabhakar ( k-H-P) fractional operator, which has the character recovering the known classical models from the proposed model, is established in this article. In order to describe the damage in the creep process, a time-varying elastic element [Formula: see text] is used in the proposed model with better representation of accelerated creep stage. According to the theory of the kinematics of deformation and the Laplace transform, the creep constitutive equation and the strain of the modified model are established and obtained. The validity and rationality of the proposed model are identified by fitting with the experimental data. Finally, the influences of the fractional derivative order [Formula: see text] and parameter k on the creep process are investigated through the sensitivity analyses with two- and three-dimensional plots.

Capillary-based effective stress formulation for predicting shear strength of unsaturated soils

2015 ◽  
Vol 52 (12) ◽  
pp. 2067-2076 ◽  
Author(s):  
Jean-Marie Konrad ◽  
Marc Lebeau
Keyword(s):  
Shear Strength ◽  
Effective Stress ◽  
Unsaturated Soils ◽  
Water Retention ◽  
Adsorbed Water ◽  
Soil Strength ◽  
Liquid Films ◽  
Degree Of Saturation ◽  
Stress Parameter ◽  
Effective Stress Parameter

A number of investigations have shown that the shear strength of unsaturated soils can be defined in terms of effective stress. The difficulty in this approach lies in quantifying the effective stress parameter, or Bishop’s parameter. Although often set equal to the degree of saturation, it has recently been suggested that the effective stress parameter should be related to an effective degree of saturation, which defines the fraction of water that contributes to soil strength. A problematic element in this approach resides in differentiating the water that contributes to soil strength from that which does not contribute to soil strength. To address this difficulty, the paper uses theoretical considerations and experimental observations to partition the water retention function into capillary and adsorptive components. Given that the thin liquid films of adsorbed water should not contribute to effective stress, the effective stress parameter is solely related to the capillary component of water retention. In sample calculations, this alternative effective stress parameter provided very good agreement with experimental data of shear strength for a variety of soil types.

A relationship describing the shear strength of unsaturated soils

1999 ◽  
Vol 36 (2) ◽  
pp. 363-368 ◽  
Author(s):  
Daud W Rassam ◽  
David J Williams
Keyword(s):  
Shear Strength ◽  
Soil Water ◽  
Nonlinear Regression ◽  
Unsaturated Soils ◽  
Characteristic Curve ◽  
Three Dimensional ◽  
Matric Suction ◽  
Linear Increase ◽  
Soil Water Characteristic Curve ◽  
Stress Dependent

A relationship describing the shear-strength profile of a desiccating soil deposit is essential for the purpose of analysis, especially when a numerical method is adopted where each zone in a discretised grid is assigned an elevation-dependent shear-strength value. The matric-suction profile of a desiccating soil deposit is nonlinear. Up to the air-entry value, an increase in matric suction is associated with a linear increase in shear strength. Beyond air entry, as the soil starts to desaturate, a nonlinear increase in shear strength occurs. The soil-water characteristic curve is stress dependent, as is the shear-strength gain as matric suction increases. In this paper, a three-dimensional, nonlinear regression analysis showed that a power-additive function is suitable to describe the variation of the shear strength of unsaturated soils with matric suction. The proposed function incorporates the effect of normal stress on the contribution of matric suction to the shear strength.Key words: air-entry value, matric suction, nonlinear regression, soil-water characteristic curve, tailings, unsaturated shear strength.

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