scholarly journals Bounding surface constitutive model for unsaturated soils considering microscopic pore structure and bonding effect

2020 ◽  
Vol 195 ◽  
pp. 02007
Author(s):  
Bowen Han ◽  
Guoqing Cai ◽  
Lin Xie ◽  
Jian Li ◽  
Chenggang Zhao
Keyword(s):  
Pore Structure ◽  
Unsaturated Soils ◽  
Characteristic Curve ◽  
Surface Model ◽  
Compression Tests ◽  
Bounding Surface ◽  
Hydraulic Hysteresis ◽  
Bonding Effect ◽  
Proposed Model ◽  
Skeleton Stress

This article presents a bounding surface model for unsaturated soils by using skeleton stress and bonding variable based on microcosmic pore structure as constitutive variables. A Hydraulic hysteresis soil-water characteristic curve model considering deformation and hydraulic hysteresis is combined to achieve hydraulic coupling. The proposed model can capture the change of the inter-particles bonding effect in the deformation process of unsaturated soils and accurately predict the hydraulic mechanical behavior of unsaturated soils under complicated loading paths and wetting-drying cycles. The validity of the proposed model is confirmed by the results of unsaturated isotropic compression tests, wetting-drying cycles tests and unsaturated triaxial shear tests reported in the literature.

Simulation of Natural Pisa Clay Using an Enhanced Anisotropic Elastoplastic Bounding Surface Model

2013 ◽  
Vol 80 (2) ◽  
Author(s):  
Jianhong Jiang ◽  
Hoe I. Ling ◽  
Victor N. Kaliakin
Keyword(s):  
Plastic Anisotropy ◽  
Complex Stress ◽  
Surface Model ◽  
Test Results ◽  
Compression Tests ◽  
Bounding Surface ◽  
Proportional Loading ◽  
Model Predictions ◽  
Loading Tests ◽  
Basic Features

The experimental behavior of natural Pisa clay under complex stress paths is simulated by an enhanced anisotropic elastoplastic bounding surface model. In its present application, the model has nine parameters and focuses on the basic features of clay behavior, such as yielding, critical state, overconsolidation and plastic anisotropy. The model is first calibrated against the test results obtained from tri-axial compression tests and subsequently used to predict the behavior of true tri-axial tests. The overall agreement between the model predictions and the experimental data is very good for proportional loading tests in both meridional and deviatoric stress spaces. The result of prediction is also compared with the original simulations that were conducted by an advanced clay model.

Volume–mass unsaturated soil constitutive model for drying–wetting under isotropic loading–unloading conditions

2011 ◽  
Vol 48 (2) ◽  
pp. 280-313 ◽  
Author(s):  
Hung Q. Pham ◽  
Delwyn G. Fredlund
Keyword(s):  
Constitutive Model ◽  
Unsaturated Soil ◽  
Unsaturated Soils ◽  
Characteristic Curve ◽  
Research Literature ◽  
Degree Of Saturation ◽  
Soil Conditions ◽  
Constitutive Relationships ◽  
Proposed Model ◽  
Wide Range

A rigorous volume–mass constitutive model is proposed for the representation of drying–wetting under isotropic loading–unloading conditions for unsaturated soils. The proposed model utilizes concepts arising from soil physics and geotechnical engineering research and requires readily obtainable soils data for soil properties. The model can be used to predict void ratio and water content constitutive relationships (and therefore degree of saturation) for a wide range of unsaturated soils. Various stress paths (i.e., loading–unloading and drying–wetting) can be simulated, and hysteresis associated with the soil-water characteristic curve is taken into account. Two closed-form equations for the volume–mass constitutive relationships are presented for soils starting from slurry conditions. A number of test results (i.e., from experimental programs reported in the research literature) were used during the verification of the proposed volume–mass constitutive model. The volume–mass constitutive model captures key unsaturated soil conditions such as air-entry value, water-entry value, and residual conditions. The proposed model appears to satisfactorily predict unsaturated soil behavior for soils ranging from low compressible sands to high compressible clays.

scholarly journals A deformation-dependent soil-water characteristic surface model considering hysteresis

2020 ◽  
Vol 195 ◽  
pp. 02014
Author(s):  
Cai Guoqing ◽  
Wu Tianchi ◽  
Li Hao ◽  
Zhao Chenggang ◽  
Tian Jingjing ◽  
...  
Keyword(s):  
Soil Water ◽  
Unsaturated Soils ◽  
Three Dimensional ◽  
Degree Of Saturation ◽  
Image Point ◽  
Surface Model ◽  
Characteristic Surface ◽  
Hydraulic Behaviour ◽  
Proposed Model ◽  
Validation Tests

The soil-water characteristic surface model plays an essential part in predicting the hydraulic behaviour of unsaturated soils. Based on the theory of plasticity bounding surface, this paper presents a three-dimensional soil-water characteristic surface model considering the effects of deformation and hysteresis. Suction and void ratio are adopted as independent variables, while the degree of saturation is adopted as a dependent variable. A new mapping rule is used where the distance between the current position and its image point can be calculated as a difference in the degree of saturation axis. The model is verified by comparing with drying-wetting tests on bentonite/kaolin mix and pearl clay. The efficiency of the proposed model is proven by validation tests.

scholarly journals A Numerical Model to Predict Matric Suction Inside Unsaturated Soils

10.14311/588 ◽  
2004 ◽  
Vol 44 (4) ◽  
Author(s):  
A. Farouk ◽  
L. Lamboj ◽  
J. Kos
Keyword(s):  
Unsaturated Soils ◽  
Characteristic Curve ◽  
Matric Suction ◽  
Coarse Grained ◽  
Soil Parameters ◽  
Measuring Devices ◽  
Proposed Model ◽  
Testing Techniques ◽  
The Relationship ◽  
Water Contents

The objective of this research is to introduce a numerical simulation model to predict approximate values of the matric suction inside unsaturated soils that have low water contents. The proposed model can be used to predict the relationship between the water content and the matric suction of a studied soil to construct the soil-water characteristic curve. In addition, the model can be utilized to combine the predicted matric suction with the soil parameters obtained experimentally, which enables us to explain how matric suction can affect the behaviour of unsaturated soils, without the need to utilize advanced measuring devices or special testing techniques. The model has given good results, especially when studying coarse-grained soils.

scholarly journals Fractional-order bounding surface model for unsaturated soils under cyclic loading

2022 ◽  
Vol 141 ◽  
pp. 104529
Author(s):  
Guoqing Cai ◽  
Bowen Han ◽  
Annan Zhou ◽  
Jian Li ◽  
Chenggang Zhao
Keyword(s):  
Cyclic Loading ◽  
Fractional Order ◽  
Unsaturated Soils ◽  
Surface Model ◽  
Bounding Surface

Soil Strength Reduction Method Induced by Variation of Water Content

2012 ◽  
Vol 170-173 ◽  
pp. 847-852
Author(s):  
Peng Ming Jiang ◽  
Zhong Lei Yan ◽  
Peng Li
Keyword(s):  
Slope Stability ◽  
Unsaturated Soil ◽  
Unsaturated Soils ◽  
Characteristic Curve ◽  
Strength Reduction ◽  
Actual State ◽  
Soil Slope ◽  
Simple Method ◽  
The Common ◽  
The Stability

As the complexity of unsaturated soil theory, and it must have a long test period when we study the unsaturated soils, so the conventional design analysis software does not provide such analysis, so we can imagine that such a slope stability analysis does not accurately reflect the actual state of the slope. Based on the known soil moisture content，this paper use the soil water characteristic curve and strength theory of unsaturated soil to calculate the strength reduction parameters of soil which can calculate the stability of the soil slope when using the common calculation method. It is noticeable that this method can be extended and applied if we establish regional databases for this simple method, and these databases can improve the accuracy of the calculation of slope stability.

Measurement of Soil Suction and Soil-Water Characteristics of Bentonite-Sand Mixtures

2010 ◽  
Author(s):  
Pan Hu ◽  
Qing Yang ◽  
Maotian Luan
Keyword(s):  
Soil Water ◽  
Vapor Phase ◽  
Unsaturated Soils ◽  
Characteristic Curve ◽  
Phase Method ◽  
Soil Suction ◽  
Compacted Bentonite ◽  
Water Characteristics ◽  
Wide Range ◽  
High Level

The soil-water characteristic curve (SWCC) is a widely used experimental means for assessing fundamental properties of unsaturated soils for a wide range of soil suction values. The study of SWCC is helpful because some properties of unsaturated soils can be predicted from it. Nowadays, much attention has been paid to the behaviours of highly compacted bentonite-sand mixtures used in engineering barriers for high level radioactive nuclear waste disposal. It is very important to study the various performances of bentonite-sand mixtures in order to insure the safety of high-level radioactive waste (HLW) repository. After an introduction to vapor phase method and osmotic technique, a laboratory study has been carried out on compacted bentonite-sand mixtures. The SWCC of bentonite-sand mixtures has been obtained and analyzed. The results show that the vapor phase method and osmotic technique is suitable to the unsaturated soils with high and low suction.

The Constitutive Model for High Temperature Flow Behavior of SiC/6168Al Composite

2015 ◽  
Vol 1089 ◽  
pp. 37-41
Author(s):  
Jiang Wang ◽  
Sheng Li Guo ◽  
Sheng Pu Liu ◽  
Cheng Liu ◽  
Qi Fei Zheng
Keyword(s):  
Constitutive Model ◽  
Hot Deformation ◽  
Flow Behavior ◽  
Type Equation ◽  
Strain Rate Range ◽  
Compression Tests ◽  
Stress Strain ◽  
Hollomon Parameter ◽  
Proposed Model ◽  
Relationship Of

The hot deformation behavior of SiC/6168Al composite was studied by means of hot compression tests in the temperature range of 300-450 °C and strain rate range of 0.01-10 s-1. The constitutive model was developed to predict the stress-strain curves of this composite during hot deformation. This model was established by considering the effect of the strain on material constants calculated by using the Zenter-Hollomon parameter in the hyperbolic Arrhenius-type equation. It was found that the relationship of n, α, Q, lnA and ε could be expressed by a five-order polynomial. The stress-strain curves obtained by this model showed a good agreement with experimental results. The proposed model can accurately describe the hot flow behavior of SiC/6168Al composite, and can be used to numerically analyze the hot forming processes.

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