Evolution law of the activation and energy storage of fault with hard rock bridge under mining influence

LYU Jinguo; HAN Wenhe; ZHANG Xuepeng; PENG Yisheng; PAN Yishan; DAI Lianpeng

doi:10.13225/j.cnki.jccs.2024.1136

Abstract：The presence of slide-resistant structures within faults alters the laws of energy accumulation and slip behavior,resulting in significant differences in the mechanisms of fault activation and instability compared to conventional under-standing.To study the evolution laws of activation and energy storage of hard rock-bridge-type faults under mining influ-ence,the activation conditions of faults with slide-resistant structures of hard rock bridges were theoretically analyzed.The slip laws of faults with hard rock bridges under mining disturbances was studied by physical simulation experiments.The differential characteristics of fault activation between faults with hard rock bridges and those without slide-resistant struc-tures were analyzed.Moreover,the variation characteristics of normal and shear stresses in the fault zones with hard rock bridges and without slide-resistant structures during the working face extraction process were studied.Using the numeric-al simulation method,the stress distribution and energy accumulation laws in the fault zones with hard rock bridges and without slide-resistant structures during the mining process near the fault were studied.The research results indicate that faults with hard rock bridges under mining disturbances exhibit more pronounced non-uniform slip behavior.However,the fault slippage amount is significantly reduced,and the degree of activation is decreased.The hard rock bridges can en-hance fault stability,and this improvement in stability is primarily reflected in the increased cohesion of the fault surface.The hard rock bridge near the working face has the highest stress concentration and is most prone to shear failure,but to a certain extent,the hard rock bridge will disperse the stress concentration zone.For fault zones without slide-resistant struc-tures,the elastic strain energy density gradually increases as mining approaches the fault,but the extent of increase re-mains limited,and the peak value of elastic strain energy density consistently occurs in the area ahead of the working face.However,The existence of hard rock bridge alters the energy distribution law in the fault zone,with the peak of strain en-ergy density is mainly concentrated in the contact between hard rock bridge and fault zone.The closer locations within the fault zone is to the rock bridge,the higher the degree of slip compression and the higher the degree of energy accumula-tion.The energy accumulation in faults containing hard rock bridges is significantly greater than in faults without slide-resistant structures.The slide-resistant structures can greatly enhance the energy storage potential of fault zones.