Study on the mechanism of roof strata instability induced by reverse fault slip under the influence of mining

Fault structures are one of the common geological structures during the coal seam mining. The slip and instability of faults not only directly change the stress state of overlying strata, but also trigger coal bursts through stress transmission and energy release. This article designs a physical simulation experiment of fault slip under the influence of mining based on the actual mining situation of the 21221 mining face in Qianqiu Coal Mine. The migration law of overlying strata is analyzed. The impact characteristics of high tectonic stress environment and mining disturbance on fault slip are studied. Fault structure potential energy is used to study the energy evolution mechanism of the interaction between faults and overlying strata. The research results indicate that faults are important areas for stress concentration and release in high stress environments. The specific manifestations of fault slip induced by mining activity are the extremum point of normal stress on the fault, a heating rate of 65.8 % and a 10.6 % decrease in the maximum fault structure potential energy in the model. When the mining face is 70 cm away from the fault, the coupling effect of fault slip and overlying strata movement is significant. Based on fault structure potential energy response characteristics near the fault under mining disturbance, the surrounding rock can be divided into strong energy zone, medium energy zone and weak energy zone. The fundamental reason for the instability of the overlying strata caused by mining is due to the high fault structure potential energy in the local area of the overlying strata. It can form a strong energy zone. When fault structure potential energy accumulates to a certain extent, the fault will slip under the influence of the strong energy zone, which can easily trigger coal burst disasters.