Abstract:
Aiming at the engineering background of shallow coal seam burial depth, thick soil layer, thin bedrock and strong disturbance of fully mechanized caving mining in the loess gully area of northern Shanxi Province, two methods of comprehensive numerical calculation and field measurement are used to explore the failure characteristics of overlying rock during mining. The simulation results show that: under the condition of strong mining disturbance, the destructive influence of mining will be transmitted from depth to shallow. With the increase of the mining distance of the working face, the displacement and deformation of the mining stratum has a cumulative effect, and the destructive effect of mining has a development process of vertical rapid development, vertical stagnation and horizontal expansion, vertical rapid breakthrough, and the ratio of the water-conducting fracture zone to the mining thickness is about 19.7; the field measurement shows that the destructive impact of mining on the 10108 working face has broken through the critical plane between the bedrock and the soil layer, the mining cracks are connected up and down, and the overlying rock layer in the goaf no longer has the ability to block water. The failure characteristics of mining overburden are mainly high-angle longitudinal fractures. The damage height of mining overburden will not be less than 198.2 m, and the ratio of the water-conducting fracture zone to the mining thickness will not be less than 22. The comprehensive research results show that: fully mechanized caving mining of thick coal seam results in more severe damage of overlying strata, and high angle of mining-induced overlying strata can lead to the development of water fractures. Although the viscous laterite with strong plastic has a restraining effect on the longitudinal development of mining-induced fractures, it cannot naturally bridge and lose the barrier of shallow unconsolidated strata and surface water in a certain period after mining at the working face. The ratio of the water-conducting fracture zone to the mining thickness is 10.5% and 9.5% different from the numerical simulation results and the empirical formula respectively. Therefore, reasonable water prevention and control measures should be formulated in time.