Characteristics of roof rock failure during coal seam mining and prediction techniques for mine water inflow in exposed karst areas

The failure characteristics of roof strata in coal mining and the accurate prediction of mine water inflow are prerequisites for mine safety. Taking a typical coal mine in Southwest China as a case, a new type of similar material suitable for coal mine in exposed karst areas was developed. Through the physical and numerical simulation, the failure characteristics of overlaying rock in karst areas were analyzed. The results showed that the plastic zone developed and accumulated from the roof. After mining, the stress and displacement of overlying rock were divided into three areas along the mining direction. The middle area experienced the maximum change. Overall, the height of falling and water-conducting fracture zones in karst exposed areas was slightly lower than that in other areas. And then, the hydrogeological structure considering the water-conducting fracture zone was rationally generalized, and a three-dimensional numerical model for predicting mine water inflow was built. It was found that the numerical simulation method had the minimum error and the maximum accuracy than other traditional methods, and its results were the closest to the measured value, which could more truly reflect the dynamic formation process of mine water inflow.