Study on the relationship between large energy events and surface subsidence in deep mining of super-thick weakly cemented overburden

Shaanxi-Mongolia mining area is an important coal mining base in China. The Jurassic coal seam overburden in the region generally has super-thick weakly cemented overburden. Although the overburden lithology is generally medium hard to weak, the measured surface subsidence is relatively small, and frequent large energy events occur, which brings great potential safety hazards for safe and efficient mining of the working face. In order to study the relationship between large energy events and surface subsidence in deep mining of super-thick weakly cemented overburden, the surface subsidence measurement and mine earthquake data analysis are conducted on the 1203 working face and 1208 working face of Shilawusu Coal Mine, and the surface movement and deformation rules and mine earthquake data of the area are obtained. Through comparative analysis, it is found that the surface movement and deformation subsidence of super-thick weakly cemented overburden is concentrated, and the maximum subsidence is located in the middle of the working face to the side of the mined working face. The overall surface subsidence basin shape and subsidence increase process are similar to those in the central and eastern parts of China. However, when the mining is not fully developed, the surface subsidence value of the western super-thick weakly cemented mining area is significantly smaller than that of the central and eastern parts. There is an active period of microseismic events in the mining process of coal seam of super-thick weakly cemented mining area. The energy and frequency of microseismic events in this stage are relatively high, and they are accompanied by large energy events with 10⁵ J≤E. Although the frequency of mine earthquake events with 10⁵ J≤E is low, they play an important role in energy release. There is a correlation between surface subsidence and energy events in weakly cemented mining areas. With the advance of working face, the maximum subsidence value mutation is often accompanied by the occurrence of large energy events.