Prediction of Overburden Failure on the Working Face Using Self-Formed Roadway Mining Technology without Coal Pillars Based on Microseismic Monitoring: A Case Study

In this study, the No.S1201-II working face of a coal mine using self-formed roadway mining technology without coal pillars was used as the engineering background, and physical experiments, numerical simulations, and field measurements were employed to study the spatiotemporal evolution laws of overburden fracture and obtain the periodic breaking law of the overburden. The results revealed the following: (1) the working face length increased after roof cutting, which led to an increase in the roadway stress on the side away from the mined area. The roof displacement remained essentially unchanged when the roadway was in the digging and cutting stages. However, the roof displacement continued to increase during the sinking and forming stages. (2) The height of the fall zone before roof cutting was approximately 17.1–19.4 m, which was 4.3–4.8 times the mining height. The maximum heights of the fracture zone on both sides and in the middle of the working face were 103.6–106.4 m and 92.4–96.1 m, respectively, corresponding to 25.9–26.6 and 23.1–24.0 times the mining height, respectively. The height of the fall zone after roof cutting was approximately 18.1 m, which was 4.5 times the mining height. The maximum heights of the fracture zone on both sides and in the middle of the working face were 100.6–105.2 m and 91.3–95.2 m, respectively, corresponding to 25.1–26.3 and 22.8–23.8 times the mining height, respectively. (3) Combined with the ground pressure behaviors and overburden breakage monitored in the field, the fracture budding phase, fracture development phase, and fracture maturation phase were divided according to the characteristics of microseismic events. A criterion for overburden deformation damage based on microseismic energy was proposed. This study provides a reference for the establishment of a microseismic-monitoring system and the application of this technology.