中文摘要：

基于Perzyna过应力理论,构造了一个土体各向异性弹黏塑性本构模型.模型引入Wheeler旋转硬化法则,能够较好的描述土体的初始各向异性和应力诱发各向异性.借助ABAQUS软件中UMAT子程序接口,模型采用隐式积分算法——图形返回算法实现.通过对一组复杂加卸荷路径的三轴不排水剪切试验（HKMD）及一组分级加载三轴不排水蠕变试验（Sachville clay）的模拟,表明本模型能够合理反映土体的率效应、应力松弛、蠕变及土体各向异性现象,验证了模型的有效性.

英文摘要：

This paper presents an improved three-dimensional anisotropic elastic-viscoplastic constitutive model based on overstress theory of Perzyna.A rotational hardening law of Wheeler is adopted to account for the initial anisotropy and the changes in anisotropy due to the viscous strains.The developed model is implemented by using ABAQUS software with UMAT subroutine,which is integrated with a return mapping algorithm.The undrained triaxial test for HKMD under complicated loading conditions and the multi-stage undrained triaxial creep test for Sachville clay were simulated by the proposed model.The simulated results show that the proposed anisotropic elastic-viscoplastic model can successfully reproduce the rate-sensitivity,relaxtion,creep and anisotropic behaviors of soft clays under different loading conditions.