横观各向同性岩土结构极限承载力的数值研究

Numerical Investigation of Ultimate Bearing Capacity for Transversely Isotropic Geostructures

基于Cosserat连续体,建立了描述横观各向同性岩土材料的弹塑性模型,在该模型中,弹性本构关系由5个变形参数描述,塑性阶段通过引入组构张量及加载方向建立了修正的Drucker-Prager准则.针对上述模型推导了一致性映射返回算法的迭代格式及模量矩阵,结合适用于Cosserat连续体的平面应变8节点减缩单元应用ABAQUS用户自定义单元接口UEL进行了数值实现.数值算例分析了各向异性程度和材料主方向对横观各向同性岩土结构的极限承载力和变形局部化模式的影响.结果表明,所建立模型能较好地模拟横观各向同性岩土结构的应变局部化行为,且较好地解决了伴随应变局部化现象出现的网格依赖性问题.

Anelastic-plastic model for transversely isotropic geostructures is developed based onthe Cosserat continuum. In the m odel , the elastic constitutive relationship is described by 5deformation parameters and the Drucker-Prager yield criterion is extended by introducing fabrictensor and loading direction in the plastic stage. The iterative format for return mapping algorithmsand the tangent modulus matrix are formulated for the proposed model . The numerical simulationis implemented based on the user subroutine （ UEL ） of A BAQUS , and a plane strain 8 -nodedreduced integrated element is used. The influence of the material principal direction and theanisotropic degree on the strain localization and the bearing capacity of the structure are analyzed.Numerical results sho w the validity and performance of the proposed model in simulating the strainlocalization behavior of transversely isotropic geostructures. Furthermore,the mesh dependencyaccompanied with strain localization is effectively solved.