Comprehensive study on the development height of water-conducting fracture zone in overburden rock of fully mechanized mining face

In response to the issue that coal mining can easily lead to the formation of fractures in the overburden, which can penetrate underground water-bearing layers and trigger mine water disasters. This study takes the 150105 working face of Panchengling Coal Industry as the research background. Theoretical formulas, underground upward hole water injection leakage detection method, borehole television imaging detection method, FLAC3D and UDEC numerical simulations were employed to comprehensively analyze the height and development patterns of the water-conducting fracture zone. The theoretical calculation results show that the maximum height of the water-conducting fracture zone is 81.56 m. Underground upward hole water injection leakage detection method monitored the water injection permeability gradient of 3 boreholes, with a critical value of 12 L/min, and determined the height range of the water-conducting fracture zone to be 78.56 m to 79.99 m. Borehole television imaging detection method observed the distribution of fractures inside the boreholes and determined the height range of the water-conducting fracture zone to be 78.39 m to 79.46 m. FLAC3D and UDEC numerical simulations results indicate, based on the characteristics of the plastic zone changes in the overlying rock, when the working face advances to 180 m, fractures occur and penetrate. The maximum height of the plastic zone reaches 76.4 m. Development pattern of the water-conducting fracture zone can be divided into three stages according to the changes in the plastic zone of the overlying rock, the distribution of vertical stress, and the vertical displacement cloud diagram. The heights of the water-conducting fracture zone is obtained by different methods and have been mutually verified.