深部节理岩体塑性损伤耦合微面模型

采用微面模型理论和损伤力学方法，建立了节理岩体的弹塑性损伤耦合微面模型. 在节理岩体的微面上，将岩体视为由节理面与岩石组成的二元介质，以节理连通率作为岩体沿该方向的面积损伤变量，考虑微面法向拉应力和压应力下的不同塑性变形和损伤耦合作用机制，基于塑性理论建立了节理岩体的微面塑性损伤增量本构关系. 采用微面物理量与宏观物理量的几何约束模型，根据微面方向积分导出了节理岩体的宏观弹塑性增量本构关系. 编制了节理岩体微面模型的MARC有限元子程序，对节理岩体的单轴拉伸、压缩试验和泥浆压力作用下的井壁稳定问题进行了数值模拟研究. 数值计算结果表明，该模型能很好地揭示载荷作用下节理岩体的各向异性非弹性变形和次生节理演化过程. 

A COUPLED ELASTO-PLASTIC MICROPLANE DAMAGE MODEL FOR JOINTED ROCK MASSES AT GREAT DEPTH

Rockwall excavated at great depth often experiences largeductile deformation and may be failure due to high compressive in-situstresses. Such phenomena are closely related to anisotropic distribution ofjoints in rock masses and mechanical response of the rock block and thejoint. To take into account the shear resistance of joint surface andanisotropic inelastic deformation related to secondary joints formation, acoupled elasto-plastic microplane damage model for jointed rock masses isdeveloped in the framework of microplane model and damage mechanics. Eachmicroplane of a jointed rock mass is regarded as a binary medium, which iscomposed of rock and joint. Joint connectivity on the microplane isintroduced as the damage variable to characterize area damage of the rockmass on that orientation due to presence of the joints. By adoptingdifferent yield function and damage evolution law for the microplane undertensile and compressive normal stress respectively, the coupled mechanismsof inelastic deformation and damage evolution are modeled. Rate formconstitutive relation of stresses and strains on microplanes is developedbased on classical plastic theory. According to the kinematic constraintcondition of microplane model, macroscopic constitutive relation is obtainedthrough directional integration along all microplanes. The presentelasto-plastic microplane damage model is implemented to the commercial FEMsoftware MARC through a user subroutine. Simulations with respect to theuniaxial tension and compression of jointed rock masses and problem ofwellbore stability under inner mud pressure are presented respectively. Ithas demonstrated that the coupled effect between anisotropic inelasticdeformation and damage evolution of jointed rock masses can be characterizedefficiently with the model.