Study on Stability of Stope Surrounding Rock under Repeated Mining in Close-Distance Coal Seams

Abstract

In order to study the influence of roof stress and fracture distribution characteristics on the stability of stope surrounding rock under repeated mining in close-distance coal seams, the research background of this paper is the close-distance coal seam mining of a mine in Guizhou province, China. The dynamic evolution characteristics of stope roof caving and the stress environment change law under repeated mining are studied by using the method of similar simulation experiment, numerical simulation, and field verification. The results show that the roof stage under repeated mining can be divided into four stages: normal mining, roof deterioration, end face roof leaks, and support crushing. The tip-to-face distance, support height, and support working condition are the main influencing factors in end face roof control. The main reason for the support crushing is that the roof above the support is broken, the main roof cannot form the self-stable structure, and the support force is insufficient. The roof dynamic load is high, and the subsidence of the end face roof is large, which is prone to roof caving during the stope roof weighting. Moreover, the roof weighting is frequent under repeated mining, which leads to the broken roof and the support cannot be supported, resulting in the occurrence of the support crushing accident. The control strategies for stope roof under repeated mining are provided based on the thorough study findings. The working face 17101 roof is successfully controlled by the aforesaid procedures, which provides the foundation for the management of stope surrounding rock under repeated loading.