考虑黏聚特性和拉压不等效应的修正剑桥模型及数值实现

 针对修正剑桥模型不能反映岩土介质黏聚特性和拉压不等效应的局限性，通过子午面上考虑黏聚力、偏平面上考虑应力罗德角的影响，建立可考虑黏聚力与拉压不等效应的非相关联修正剑桥模型；较系统地介绍所修正模型的Euler向后隐式本构积分算法及程序实现过程。应用ABAQUS软件所提供的用户材料子程序UMAT接口，编制改进修正剑桥模型本构子程序，并运用所编程序研究比利时Boom clay的三轴压缩力学行为。研究结果表明，所编子程序具有较高的计算精度和良好的稳定性，所改进模型能较好地反映Boom clay的非线性与塑性流动特性。

MODIFIED CAM-CLAY MODEL CONSIDERING COHESION AND S-D EFFECT AND ITS NUMERICAL IMPLEMENTATION

Due to the conventional modified Cam-clay model can not describe the cohesion properties and different yield strengths in tension and compression performance (S-D effect for short) for geotechnical materials，a modified Cam-clay model with non-associated flow rule is established considering S-D effect on deviatoric plane and cohesion on meridian plane. The main contents of implicit constitutive integration algorithm for the improved model and its implementation procedure are discussed systematically. Based on the platform of software ABAQUS，the user-defined material subroutine UMAT interface is developed to generate corresponding constitutive subroutine of the modified Cam-clay model. Meanwhile，the numerical simulation of triaxial compression test on Belgium Boom clay is implemented. The study result shows that the improved constitutive model and the UMAT subroutine have higher calculation accuracy and good stability，which could effectively depict the nonlinear and plastic flow characteristics of Belgium Boom clay.