平面应变含缺陷岩样变形破坏全过程数值模拟

Numerical Simulation of Complete Failure Process of Rock with Material Imperfection in Plane Compression Strain

采用拉格朗日元法(FLAC)研究了左边界有缺陷的压缩岩样剪切带的启动及演变规律,峰后本构关系采用线性应变软化模型.计算结果表明,在应力-时步曲线峰值之前,剪切带首先出现在缺陷附近,直到贯通试样右边界;在剪切带传播过程中,塑性区沿切向及法线向外扩展;剪切带内部单元的剪切应变率-时步曲线经历了稳定、线性上升和非线性上升3个阶段.然而,剪切应变增量随时步持续增加.剪切带倾角接近于Arthur倾角,表明数值计算结果是可信的.

The initiation and evolution of a shear band in rock specimens with material imperfection at their left edges in a compression state were investigated using FLAC (fast lagrangian analysis of continua). In this investigation, a linear strain-softening post-peak constitutive relation was adopted. The computational result shows that a shear band (SB) occurs in the vicinity of the imperfection when the stress of a rock specimen is less than its peak strength, and continuously develops until the right edge. In the process of shear band propagation, a plastic zone extends towards the SB's normal and tangential directions. The evolution of the plastic zone is similar to that of the SB. The shear strain rate-timestep curve of elements in the SB undergoes three stages, i.e., approximately unchanged, linearly and non-linearly increasing stages of shear strain rate. However, shear strain increment in the SB increases continuously with timestep. SB's inclination approaches to Arthur's inclination, which suggests that the numerical simulation results are reasonable.