岩土材料的各向异性性质与其微结构紧密相关，文中考虑到内摩擦角是应力状态、组构张量及材料主方向的函数，发展了适用于横观各向同性岩土材料的修正的 Druck-
er-Prager 屈服准则． 基于 Cosserat 连续体理论，推导了该准则的一致性映射返回算法，形成了一致性切线模量矩阵，并利用有限元软件 Abaqus 的用户单元子程序(UEL)进行了数值实现． 通过将积分点材料强度随材料主方向及各向异性程度的变化关系与理论结果进行比较，验证了程序开发的正确性． 数值算例重点分析了材料主方向和各向异性参数对结构极限承载力及破坏模式的影响，且与经典连续体的结果进行了比较． 结果表明，文中方法能够较好地模拟具有横观各向同性的岩土材料的应变局部化现象．

The anisotropic properties of geomaterials are significantly related to their inherent microstructures.In this paper,a modified Drucker-Prager yield criterion for transversely isotropic materials is developed by evaluating the internal friction angle with the stress state,the microstructure tensor and the material principal direction.Then,based on the Cosserat continuum theory,a consistent return mapping algorithm for the modified criterion is formulated,and a consistent tangent modulus matrix is achieved.Moreover,the codes are implemented through the user defined element subroutine (UEL) in the finite element software Abaqus,and the correctness of the pro- gram is verified by comparing the theoretical results with the relationships of the material strength to the principal direction and anisotropic degree of the material in the integration points.Finally,the influences of the principal direction and anisotropic degree of the material on the bearing capacity and the failure mode of the structure are em- phatically analyzed by numerical examples,which are then compared with the results based on the classical contin- uum theory.It is found that the above-mentioned method is effective in simulating the strain localization of trans- versely isotropic geomaterials.