Study on Post-Peak Stress Surge in Closed Jointed Coal by Direct Shear Test Based on Particle Flow Code Method

The Particle Flow Code (PFC) program is used to generate the closed joint numerical model of coal. First, the direct shear test of LPBM as the rock contact model SJCM as the closed joint contact model is carried out. Then the direct shear test of FJM as the rock contact model SJCM as the closed joint contact model is carried out. The post-peak stress surge phenomenon of SJCM as the contact model of closed joint is studied under the condition of rock with different contact models. The results show that when the shear displacement exceeds the minimum particle diameter, the shear stress of the closed jointed rock based on LPBM and SJCM will suddenly increase, while this phenomenon does not appear in the closed jointed rock based on FJM and SJCM, which is found to be caused by the defects of LPBM itself.