摘要
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.
Rockwall excavated at great depth often experiences large ductile deformation and may be failure due to high compressive in-situ stresses.Such phenomena are closely related to anisotropic distribution of joints in rock masses and mechanical response of the rock block and the joint.To take into account the shear resistance of joint surface and anisotropic inelastic deformation related to secondary joints formation, a coupled elasto-plastic microplane damage model for jointed rock masses is developed in the framework of microplane model and damage mechanics.Each microplane of a jointed rock mass is regarded as a binary medium,which is composed of rock and joint.Joint connectivity on the microplane is introduced as the damage variable to characterize area damage of the rock mass on that orientation due to presence of the joints.By adopting different yield function and damage evolution law for the microplane under tensile and compressive normal stress respectively,the coupled mechanisms of inelastic deformation and damage evolution are modeled. Rate form constitutive relation of stresses and strains on microplanes is developed based on classical plastic theory.According to the kinematic constraint condition of microplane model,macroscopic constitutive relation is obtained through directional integration along all microplanes.The present elasto-plastic microplane damage model is implemented to the commercial FEM software MARC through a user subroutine.Simulations with respect to the uniaxial tension and compression of jointed rock masses and problem of wellbore stability under inner mud pressure are presented respectively.It has demonstrated that the coupled effect between anisotropic inelastic deformation and damage evolution of jointed rock masses can be characterized efficiently with the model.
出处
《力学学报》
EI
CSCD
北大核心
2008年第5期672-683,共12页
Chinese Journal of Theoretical and Applied Mechanics
基金
国家重点基础研究发展规划(973)(2006CB202210)
清华大学水沙科学与水利水电工程国家重点实验室开放研究基金(sklhse-2007-D-02)资助项目~~
关键词
深部岩体
节理连通率
微面模型
塑性损伤耦合
井壁稳定
rock masses at great depth
joint connectivity
microplane model
damage coupled elasto-plastic
wellbore stability
