Disaster causing mechanism and monitoring of dynamic and static load coupling of deep multi layer hard roof

The change of stope migration caused by the failure and instability of the overlying thick key strata has a control effect on the occurrence of rock burst in front of the working face. The main disaster-causing factors of rock burst in front of the working face are explored to predict and prevent rock burst. Through the distribution characteristics of microseismic energy events, it is determined that the instability of hard roof has a great influence on the mining of working face. The influence mechanism of the instability and fracture of the overlying hard rock strata on the rock burst of the working face is clarified, and the distribution of the advance abutment pressure of the working face and the energy accumulation of the coal and rock mass under the static load condition are calculated by establishing the mechanical model of the advance abutment pressure of the working face under the condition of full mining. The superposition of dynamic and static load energy on the working face by the initial and periodic instability fracture and synergistic fracture energy release of the overlying hard rock strata is calculated theoretically. It is determined that the superposition energy transmitted to the working face by the synergistic fracture of the middle and low hard rock strata is 1.23 × 10⁴ J, which is higher than the critical energy of Gengcun rock burst. The low hard rock layer is determined as the monitoring target layer, and the on-line monitoring scheme of hard rock layer activity is established. The dynamic change of anchor cable data of stress evolution law of low hard rock layer in the process of working face mining is quantitatively determined, which reflects the stress evolution law of coal and rock mass in front of working face, and quantitatively determines the three-stage division of the influence of working face mining on coal and rock mass in front of working face.