土体边界面模型在ABAQUS软件中的研发与验证

Implementation of Anisotropic Bounding Surface Model on ABAQUS Software

摘要:

天然土体一般都处于偏压固结状态，存在着初始各向异性.即使是等压固结土体，在其后的偏压加载过程中，也会产生应力诱发各向异性.土体各向异性对其强度、变形及屈服面倾向都会产生影响.Wheeler弹塑性模型采用旋转硬化来描述土体的各向异性.在Wheeler模型的基础上，结合边界面理论，将Wheeler模型拓展为各向异性边界面模型.模型采用ABAQUS软件的UMAT子程序接口，通过隐式积分算法（图形返回算法）编程实现.采用本模型对高岭土三轴不排水剪切试验进行了模拟，并与试验结果作了对比验证.结果表明：模型能够合理描述具有初始各向异性土体的应力应变行为、孔压曲线及应力路径,并能反映偏压加载下的应力诱发各向异性；模型既可适用于模拟正常固结土，也适用于对中等超固结土的模拟.

Abstract:

Natural soft clay tends to be anisotropy developed during deposition, one dimensional consolidation, and any subsequent straining. Anisotropy of clays affects its shear strength, stress strain response, yield surface declination, and so on. An anisotropic bounding surface model is developed based on Wheeler’s elastoplastic model (S CLAY1). The developed model is programmed in ABAQUS software by writing UMAT subroutine, which is integrated in return mapping algorithm. The developed bounding surface model is validated with undrained triaxial shear test of Kaolin clay. The study shows that the developed model can well simulate the stress strain behaviors and the change of excess pore pressure of normally consolidated and over consolidated clays. Meanwhile, the developed bounding surface model can also efficiently depict the initial anisotropy and stress induced anisotropy of consolidated natural soft clay.