scholarly journals Investigation of Lade-Kim Plastic Potential Applicability under Various Stress Paths for Rockfill Materials

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Liping Chen ◽  
Shihai Bian ◽  
Xiaokai Niu ◽  
Yongbo Zhao
Keyword(s):  
Path Dependence ◽  
Stress Path ◽  
Constant Stress ◽  
Coarse Grained ◽  
Triaxial Tests ◽  
Stress Increment ◽  
Verification Method ◽  
Rockfill Materials ◽  
Plastic Potential ◽  
Increment Ratio

The dilatancy behavior of rockfill materials shows obvious stress path dependence. Lade-Kim plastic potential equation has been proposed for a long time to model the mechanical behavior of sand and concrete materials. However, it lacks the verification of rockfill materials, especially under various stress paths. In this paper, the dilatancy performance of coarse-grained materials under various stress paths is investigated, and then the dilatancy equation description and verification method based on Lade-Kim plastic potential are given. The applicability of Lade-Kim plastic potential for different stress path tests, such as conventional triaxial tests, constant P tests, and constant stress (increment) ratio tests, are verified and evaluated. It is found that Lade-Kim plastic potential is difficult to consider the influence of stress path. Finally, the Lade-Kim plastic potential, together with nonlinear dilatancy equation, is evaluated by changing the dilatancy equation in the framework of generalized plasticity. Lade-Kim plastic potential is suitable for constant stress increment ratio loading experiments and special care should be taken when applied to other stress paths. These works are helpful to understand stress path dependence of dilatancy behavior for rockfill materials and is beneficial for the establishment of stress path constitutive model.

An Elastoplastic Model for Coarse Grained Soils Obeying Lade's Dilatancy Rule

2013 ◽  
Vol 850-851 ◽  
pp. 381-386
Author(s):  
Jin Wang ◽  
Jiao Na Li ◽  
Sheng Zhu
Keyword(s):  
Potential Function ◽  
Yield Surface ◽  
Large Scale ◽  
Coarse Grained ◽  
Triaxial Tests ◽  
Surface Model ◽  
Test Results ◽  
Elastoplastic Model ◽  
Plastic Potential ◽  
Plastic Potential Function

This paper discussed the mechanism of dilatancy in coarse grained soils. Large-scale triaxial tests were also conducted to study the dilatancy law of coarse grained soils. Based on the results of the previous studies, it is found that plastic potential function proposed by Lade can fit the test results well. Lades dilatancy rule was then applied to a practical two-yield-surface model. Elastoplastic formula of the two-yield-surface model was also deduced in detail. The new model was verified with several groups of different materials. Results showed that this model could predict the behaviors of coarse grained soils well.

Unified hardening (UH) model for overconsolidated unsaturated soils

2014 ◽  
Vol 51 (7) ◽  
pp. 810-821 ◽  
Author(s):  
Y.P. Yao ◽  
L. Niu ◽  
W.J. Cui
Keyword(s):  
Unsaturated Soils ◽  
Path Dependence ◽  
Three Dimensional ◽  
Constitutive Models ◽  
Stress Path ◽  
Triaxial Tests ◽  
Additional Material ◽  
Basic Model ◽  
Proposed Model ◽  
Unsaturated Clays

Naturally deposited clays are often unsaturated and overconsolidated. Within the frameworks of the Barcelona Basic model (BBM) for normally consolidated unsaturated clays and the unified hardening (UH) model for overconsolidated saturated clays, a three-dimensional constitutive model for overconsolidated unsaturated clays is proposed in this paper. This model can be reduced to the original UH model for overconsolidated saturated clays when suction becomes zero and the BBM when the overconsolidated behaviour disappears. Compared with existing constitutive models for unsaturated clays, the influence of a high overconsolidation ratio (OCR) on wetting deformation can be adequately described. Also, many other characteristics of overconsolidated unsaturated clays can be modelled, including strain-hardening, softening, shear dilatancy, and stress path–dependence behaviour. Compared with the BBM, the proposed model requires no additional material parameter. The validity of the UH model for overconsolidated unsaturated clays has been confirmed by data from two groups of wetting tests performed by the authors and previous triaxial tests in the literature.

scholarly journals Testing and Micromechanical Modelling of Rockfill Materials Considering the Effect of Stress Path

2016 ◽  
Vol 2016 ◽  
pp. 1-14 ◽  
Author(s):  
Wang Feng ◽  
Chi Shichun ◽  
Li Shijie ◽  
Jia Yufeng
Keyword(s):  
Stress Ratio ◽  
Volumetric Strain ◽  
Stress Path ◽  
Complex Stress ◽  
Triaxial Tests ◽  
Rockfill Material ◽  
Rockfill Materials ◽  
Deformation Properties ◽  
Confining Pressures ◽  
Improved Model

We have extended the micromechanics-based analytical (M-A) model to make it capable of simulating Nuozhadu rockfill material (NRFM) under different stress paths. Two types of drained triaxial tests on NRFM were conducted, namely, the stress paths of constant stress ratio (CSR) and the complex stress paths with transitional features. The model was improved by considering the interparticle parameter variation with the unloading-reloading cycles and the effect of the stress transition path. The evolution of local dilatancy at interparticle planes due to an externally applied load is also discussed. Compared with Duncan-Chang’s E-u and E-B models, the improved model could not only better describe the deformation properties of NRFM under the stress path loading, but also present the volumetric strain changing from dilatancy to contractancy with increasing transitional confining pressures. All simulations have demonstrated that the proposed M-A model is capable of modelling the mechanical behaviour of NRFM in the dam.

Effects of Stress Path and Stress History on the Stiffness of Reconstituted London Clay

1986 ◽  
Vol 2 (1) ◽  
pp. 139-144 ◽  
Author(s):  
J. H. Atkinson ◽  
J. S. Evans ◽  
D. Richardson
Keyword(s):  
Stress Path ◽  
Triaxial Tests ◽  
Soil Parameters ◽  
Stress History ◽  
Strain Behaviour ◽  
Reconstituted Soil ◽  
Path Dependent ◽  
London Clay ◽  
Soil Behaviour

AbstractSoil behaviour is stress history dependent and stress path dependent and soil parameters, particularly those for stress-strain behaviour, measured in conventional triaxial tests may not represent the behaviour of soil in many civil engineering works.To obtain more realistic parameters it may be necessary to conduct laboratory tests which more closely represent in situ conditions before and during construction.The paper describes equipment developed at The City University to carry out stress path tests simply and economically. A series of CU triaxial tests and stress path tests on reconstituted soil illustrate the dependence of measured soil parameters on stress history and stress path.

Micro Parameters Sensitivity of Coarse Grained Material in Mechanics and Deformation Based on PFC3D

2016 ◽  
Vol 873 ◽  
pp. 115-119
Author(s):  
Zhi Hua Zhang ◽  
Xie Dong Zhang ◽  
Hong Sheng Qiu ◽  
Bei Yang Zhang
Keyword(s):  
Weighted Average ◽  
Shear Stiffness ◽  
Coarse Grained ◽  
Triaxial Tests ◽  
Deformation Analysis ◽  
Analysis Method ◽  
Particle Rotation ◽  
Sensitivity Curves ◽  
Coarse Grained Material ◽  
Strength And Deformation

In order to study the effects of various parameters on macro-mechanical and deformational characteristics of coarse grained material based on discrete element method, triaxial tests have been conducted. Weighted average assembling method is used to assemble the numerical model based on PFC3D. The ratio of normal and shear stiffness of particles (kn/ks), shearing rate and friction coefficient are chosen as micro parameters to analyze the influential sensitivity. Curves of stress-strain intensity are taken as the mechanical analytic method. The particle rotation field as deformation analysis method is proposed to sort the sensitivity of these parameters in strength and deformation of coarse grained material. The research shows that the parameters have a certain effect on the strength and deformation of coarse grained material. kn/ks has the greatest influence on both. The sensitive list of the strength and deformation hopefully can be discussed with the relevant scholars, which can provide a reference for the adjustment of micro parameters in numerical field.

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