Prediction of development height of water-conducting fracture zone based on rotational subsidence

The development height of water-conducting fracture zone(WCFZ) is an important parameter for water disaster treatment in coal mine roof. In this paper, the failure process of mining overlying rock is analyzed, and the rock instability failure in the fracture zone is divided into three stages: vertical fracture formation, masonry structure formation and gyratory instability; a mechanical model of vertical cracks and gyration subsidence is established. On this basis, the maximum subsidence of vertical cracks and gyration instability is analyzed to judge the rock failure. The rock stratum with gyration subsidence value between these two stages forms a stable masonry beam structure, and a new method for calculating the height of WCFZ is obtained. Taking the 2201 working face of Yingpanhao as an example, the height of the WCFZ is predicted by theoretical method and numerical simulation. By comparing with the field measured data, the theoretical calculation (123.3 m) and numerical simulation results (132 m) are close to the measured data (115.5 m), which verifies the rationality of the proposed method.