关键词: 非共面双裂隙, 破坏模式, 裂纹演化规律

Abstract: With the increasing depth of mine excavation，the problem of working face instability caused by confining pressure and natural defects has become a hot topic. Based on the indoor mechanical test and discrete element numerical method，the mechanical strength，deformation characteristics，failure mode and internal crack evolution law of non-coplanar double-fractured coal rock with under different con⁃ fining pressures are analyzed for the coal samples of Hepan Coal Mine in Shenmu City，Shaanxi Province. The results show that the mechanical properties of coal and rock meet the Mohr-Coulomb criterion. With the increase of confining pressure，the peak strength and peak strain increase linearly. The non-coplanar dou⁃ ble fractures with different rock bridge angles have obvious deterioration effect on the mechanical parame⁃ ters of coal rock. When the rock bridge angle is 0°，30°，60°，90°and 120°，the peak strength of coal sam⁃ ples decreases by 16.4%，14.2%，26.4%，38.5% and 19.8%，respectively. Compared with the rock bridge angle，the confining pressure has a greater influence on the failure mode of the sample. With the increase of confining pressure，the coal sample changes from tensile-mixed tensile-shear failure to shear failure，and the coal rock changes from brittle failure to ductile failure. In addition，the number of cracks is also affected by the confining pressure and the dip angle of rock bridge. The research results provide certain guiding for the safety and stability of deep mine mining.

Key words: non-coplanar double fractures, failure mode, crack evolution law