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基于Wheeler土体各向异性旋转硬化法则,结合边界面理论,构造一个能够反映土体初始各向异性及加载后应力诱发各向异性的边界面本构模型,并借助ABAQUS软件提供的UMAT子程序接口,采用隐式积分算法——图形返回算法实现。通过对正常固结状态下(OCR=1)高岭土试样三轴不排水剪切试验进行模拟,并将模拟结果与ABAQUS自带的修正剑桥模型模拟结果进行了比较分析,表明本模型的模拟结果能够反映土体在偏压加载过程中产生的各向异性现象。在此基础上,采用本模型对中等超固结(OCR=4)高岭土试样三轴不排水剪切试验进行模拟,并再次与ABAQUS自带的修正剑桥模型模拟结果进行比较,表明本模型能够较好地反映中等超固结土在小应变情况下的非线性特性。相比于经典弹塑性模型,如修正剑桥模型,本模型的模拟结果更符合中等超固结土的变形特性。
Based on Wheeler anisotropy law of rotation and hardening, combined with the theory of boundary surface, a constitutive model of boundary surface that can reflect the initial anisotropy of soil and the stress-induced anisotropy after loading is constructed. With the UMAT subroutine provided by ABAQUS software Interface, the use of implicit integration algorithm - graphics return algorithm. Through the three-axis undrained shearing test of kaolin clay specimen under normal consolidation condition (OCR = 1), the simulation results are compared with the modified Cambridge model simulation results of ABAQUS, which shows that the simulation results of this model Can reflect the anisotropic phenomenon that the soil produces in the biased loading process. On this basis, this model is used to simulate the undrained triaxial shear tests of medium overconsolidated (OCR = 4) kaolinite specimens and again compared with the modified Cambridge model simulation results of ABAQUS. The results show that this model can It can well reflect the nonlinear characteristics of medium overconsolidated soil in the condition of small strain. Compared with the classical elasto-plastic model, such as the modified Cambridge model, the simulation results of this model are more in line with the deformation characteristics of medium overconsolidated soil.