The study of mining-induced behaviors of faults and strata in underground coalmines is significant to know the mechanism and prediction of some accidents (i.e., water inrush, gas flowing and outburst). Equivalent materials are applied herein in an underground project to simulate a progressive mining operation with a normal fault occurrence. The failure–movement evolution of the overlying strata and the stress–displacement evolution of the fault are studied through a physical simulation test. The formation of a mining-induced fracture and the mechanism of accidents caused by the mining-induced fracture are analyzed. The results show that the footwall strata underwent a more notable movement compared to the hanging wall strata. Hence, the mining-induced fracture height of the footwall is higher than that of the hanging wall. The effect of the fault can be observed on the mining-induced fracture evolution of the footwall, hanging wall, and fault plane. The developed patterns of the fracture channel successively present an evolution in the shape of a “saddle”, a “trapezium”, and an “M”. The causes of accidents induced by the mining fracture are also discussed.
Using the FLAC3D numerical simulation method, the characteristics of mining stress evolution, fault activation patterns, and fault energy evolution characteristics are simulated and analyzed in the process of the footwall and hanging wall working face heading to a normal fault. The study shows that the fault cut off the mining stress propagation of overlying strata, and the stress blocking effect due to the fault is evident. When working faces head towards a fault, the abutment pressure and the vertical stress of the surrounding rock increase first and subsequently decrease. The abutment pressure of the coal wall and fault is highest when the distances to the fault are 40 m and 30 m for the footwall and hanging wall working faces, respectively. Moreover, the hanging wall mining stress is higher than the footwall mining stress. Fault activation in high-located strata precedes that in low-located strata when working faces head towards the normal fault. Energy is gradually accumulated before unstable fault events take place because of mining, and fault instability quickly releases a lot of energy. The mining stress concentration and fault activation due to faults easily result in rock bursts and mine seismicity, Wu Quan-sen, Jiang Li-shuai and Wu Quan-lin., and Obsahuje bibliografické odkazy