TWIN SHEAR UNIFIED ELASTOPLASTIC CONSTITUTIVE MODEL CONSIDERING STRAIN SOFTENING BEHAVIOR
LI Hangzhou1,2,LIAO Hongjian1,SONG Li1,REN Jianing1,LENG Xianlun2
(1. Department of Civil Engineering,Xi?an Jiaotong University,Xi?an,Shaanxi 710049,China;2. State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,
Wuhan,Hubei 430071,China)
Abstract:A yield function and a potential function were determined according to the twin shear unified strength theory. The hardening function of soils was established considering the development of soil strength during loading. An elastoplastic constitutive relationship under the complex stress state was proposed using the non-associated flow rule. The singularities in the constitutive model caused by the flow vectors of yield and potential functions and the hardening modulus were analyzed and resolved. The method of determining the parameters of the proposed model is presented. It was shown that the proposed constitutive model fit the strain softening curves from a conventional triaxial experiment of mudstone well.