Mechanism of fault reactivation and its induced coal burst caused by coal mining activities

In this paper, the relationships between coal mining layouts and fault occurrences have first been investigated to summarize the relevant conceptual models. Subsequently, the mechanisms of fault reactivations dominated by mining-induced stress andby seismic-based dynamic stresshave been proposed, and the resultant induced coal bursts have been interpreted from the superposition point of static and dynamic stresses. These two types of fault reactivations have then been validated by the results of numerical modelling, similar material simulation and microseismic monitoring. On this basis, the corresponding monitoring methods and prevention strategies for fault-induced coal burst have been discussed. The results have shown that fault-induced coal burst is triggered by the superposition of the high static stress in the fault pillar resulted from the interaction of fault and roof structure and the dynamic stress from the fault reactivation dominated by mining-induced stress or by seismic-based dynamic stress. Moreover, the fault reactivation is mainly related to the cohesion, friction angle, dip angle of the fault plane, the minimum principal stress and the pore pressure. In particular, the decrease of the lateral pressure coefficient, dominated by the mining-induced stress with the vertical stress increasing and the horizontal stress decreasing, is the main mechanical essence of the fault reactivation. An ultra-low friction phenomenon generated from a dynamic loading is the main intrinsic mechanism of the fault reactivation dominated by the seismic-based dynamic stress. The results in this paper could be of great guiding significance for the monitoring and prevention of fault-induced coal burst. © 2019, Editorial Board of Journal of Mining & Safety Engineering. All right reserved.