Study on the influence of lateral stress on fracture instability and impact of static load coal roadway

It is of great significance to carry out the research on concentrated static load type rock burst to reveal the occurrence process of rock burst events under static load in solid coal roadway and improve the design scheme of roadway support. Based on the research background of roadway instability and failure under the horizontal stress of the return wind groove of 6126⁻¹ longwall working face in Gansu Province, China. The influence of lateral stress on the instability failure and impact hazard of coal roadway during the slow migration and superposition of overlying load is studied through the self-designed loading system of coal roadway structure. In the experiment, three lateral stress levels of 0 MPa, 2.2 MPa and 4.5 MPa are preset to simulate the near-field lateral pressure of the coal roadway, and the acoustic emission and camera system are used to capture the structural instability process of the coal roadway, and the mechanism of gradual failure and impact disaster of the coal roadway under different lateral stresses is discussed. The results show that the instability and impact processes of coal roadway and coal sample（column） under overlying static load are different, and the elastic brittle failure coal sample shows obvious post-peak strain softening characteristics in the coal roadway structure, resulting in the impact tendency of the coal roadway structure is reduced compared with that of the coal sample（column）, but the high lateral stress will significantly increase the impact risk of the coal roadway. There are also obvious differences in the crack evolution law, and the proportion of shear cracks reaches the maximum value around the peak stress of 50% in the crack pre-peak transition from tensile to shear crack mode in the coal gang failure process, and the larger the lateral stress, the smaller the transition degree of shear crack mode before and after the peak, and the higher the proportion of shear cracks. According to the research results, the on-site roadway anti-erosion and pressure relief and support scheme are optimized, which provides engineering reference for the prevention and control of rock burst in coal roadway under similar conditions.