Horizontal Extension Law of Water and Sand Inrush Channel in Thin Bedrock of Mining Area

Conducted fissure channel through thick aeolian sand is produced in the thin bedrock under the influence of mining, which causes the disaster of water inrush and sand inrush. In order to study the extension law of water flowing fractured channel in thin bedrock, a thin bedrock model with complex stress was established based on the particle discrete element theory. The influence of water and sand pressure, primary fracture length and overburden pressure on horizontal extension law of fracture in thin bedrock plane was analyzed. The following results were achieved: (?) The relationship between the number of cracks and running time can be divided into 4 stages: Elastic stage, crack propagation stage, fracture stability stage and failure stage. (?) Extended fractures can develop into “X” and “Y” types at the tip of primary fracture. (?) 4 stages of fracture extension under the influence of different primary fractures, different overburden pressure and different water effect were studied. In addition, failure curves were given, and the quantitative relationship between the influences of different conditions on the fracture propagation was analyzed.