Deformation and Failure Characteristics of Overburden Under Thin Bedrock and Thick Alluvium: A Case Study in Baodian Coal Mine

Underground mining will lead to deformation and failure of overburden and frequently associated with water inrush. In view of the special situation of No.8 mining area in Baodian Coal Mine (thin bedrock and thick alluvium). According to geological engineering characteristics and overlying lithified strata, different bedrock height models were established using physical and numerical simulation. The deformation and failure of overburden, mining-induced stress, and height of the caving zone are then studied using these models. The results show that mining-induced stress is different in overburden and clay, with a large variation near the rock and clay layers. Findings also illustrate that the clay layer has an inhibitory effect on mining-induced stress. The height of the caving zone increases with the height of the bedrock, and the height of the caving zone obtained by physical and numerical simulation are similar. Through the comprehensive comparison of the height of the caving zone, it can be inferred that the height of the caving zone does not reach the thinnest position of the bedrock and no large water inrush will occur. The results obtained in this study provide an important framework for the study of coal mining safety under similar geological conditions in other locations.