Evolution Mechanism of Water-Conducting Fissures in Overlying Rock Strata with Karst Caves under the Influence of Coal Mining

Abstract

There are a large number of karst caves in the limestone rock strata in the karst mining area, and the karst water in rock strata seriously restricts the safe and efficient recovery of coal resources. In order to reveal the influence law of karst caves of rock strata on the evolution of water-conducting fissures in coal seam mining, the numerical simulation method in UDEC software is employed to analyze the development characteristics of water-conducting fissures in coal seam mining under the conditions of karst caves of different sizes. By comparing and analyzing the development characteristics of overlying fissures in rock strata and the displacement fields in coal seam mining under the conditions of different karst caves, the evolution law of water-conducting fissures in coal seam mining is obtained. The research results show that the size of karst cave directly affects the maximum height of the water-conducting fissures in the overlying rock strata in coal seam mining; when the thickness of the coal seam is 3.0 m, the larger the radius of karst cave is, the higher the development height of water-conducting fissures in the overlying rock strata is, and the greater the overall sinking displacement in the Yulongshan limestone is. When the radius of karst cave is between 10 m and 15 m, a through-type water-conducting channel is formed between the working face and the karst cave after the coal seam is mined, and the numerical simulation results are consistent with the field monitoring results. The research results provide an important reference for the prevention and treatment for water inrush disaster in karst mining areas.