岩石节理剪切力学行为的颗粒流数值模拟

 利用颗粒流程序生成岩石节理直剪试验数值模型，进行不同法向应力作用下节理直剪试验的颗粒流数值模拟，研究节理的宏细观剪切力学行为，以及不同法向应力作用下微裂纹的发育及演化规律。结果表明：模型试件在直接剪切过程中表现出类似于真实节理的宏观力学行为，试件的抗剪强度和剪切峰值剪胀角对法向应力的依存关系体现出与JRC-JCS模型预测结果良好的一致性；模型试件主要在节理面两侧的微凸体附近产生接触压力集中现象。法向应力越大，接触压力集中区越多，集中程度越高；随法向应力不断增大，试件内微裂纹的发育速度逐步提高，剪切裂纹发育数目在微裂纹总数中所占的比例逐步增大，但仍远少于张性裂纹；节理面上接触压力的分布特征与模型试件内微裂纹的发育规律一致；节理在外荷载作用下的剪切破坏是节理面上微裂纹汇集贯通的结果，“压致拉”效应在此过程中起主导作用。

PARTICLE FLOW CODE MODELING OF SHEAR BEHAVIOR OF ROCK JOINTS

Numerical model of rock joint was generated and direct shear tests at different normal stresses were conducted using PFC2D. Shear behavior of the rock joint，along with development and evolution law of microcracks at different normal stresses were examined. It is shown that the shear behavior of simulated joints corresponds well to that observed in real joints；and the dependencies of shear strength and peak dilatation angle on normal stresses conform well to predict results of the JRC-JCS model. Compressive contact force mainly concentrates nearby asperities on both sides of the joint plane. The larger the normal stress is，the more concentrated areas of confact force will appear，and the higher the concentration degree is. As normal stress continues to enhance，the developing rate of microcracks within the specimen gradually increases；and the proportion of shear cracks to the total number of microcracks gradually enlarges；but they still far less than the tension cracks. The distribution characteristics of compressive contact force on joint surface are consistent with the development law of microcracks in the specimen. Shear failure of joint under external load results from convergence and correlation of microcracks in the joint plane；and the effect of compression induced tensile cracking plays a dominant role in the process of joint shear failure.