Regional failure mechanism of main roof and zonal method for ground control in kilometer-deep longwall panel with large face length

Mining depth and face length increase gradually in coal mine. The intensity of mining pressure occurrence rises quickly. In order to improve ground control in deep longwall panel with large face length, a case study is carried out by taking 121304 longwall panel in the Kouzidong Coal Mine of Xinji Energy Co., Ltd., China National Coal Group Corp as the background. Roof micro-seismicity characteristics are summarized, aiming to reveal the mechanisms of regional failure and dynamic migration in main roof. The works are conducted by using field measurement, theoretical analysis and lab test. The results show support resistance presents valley-shaped distribution, characterized by small resistance in middle region and large resistance in side regions. At different face advancement, the location of roof rupture induced micro-seismic events with large magnitude changes dynamically along face length direction, indicating regional failure and dynamic migration of main roof. The energy associated with the strong event