Abstract:
To study the development height of the water-conducting fracture zone (WCFZ) in the steeply inclined longwall fully-mechanized top-coal caving face, the 202 fully-mechanized caving face in the west No.2 mining area of Wangjiashan Coal Mine was taken as the research object, and comprehensive methods including empirical formula calculation, physical similarity simulation, numerical simulation and on-site actual measurement were adopted to analyze the dynamic evolution law of the water-conducting fractured zone in steeply inclined coal seams. The results show that the filling degree of caved rocks in the goaf presents a distribution characteristic of inclined middle part > inclined lower part > inclined upper part. Due to the existence of an articulated structure in the inclined lower part, a large-scale void space is formed in the goaf; meanwhile, since the height of the water-conducting fracture zone has penetrated the roof aquifer, this area is prone to water accumulation. With the advancement of the working face, the continuous instability of the overlying strata reduces the pressure on the void space, resulting in the formation of confined water in the accumulated water. In the inclined direction of the working face, the water-conducting fracture zone (WCFZ) of the steeply inclined longwall fully-mechanized top-coal caving face presents an asymmetric trapezoidal shape. During initial mining, the highest point of the development height of fracture zone is located in the upper-middle part of the working face along the incline; with the continuous advancement of the working face, this highest point gradually shifts to the upper part of the incline and finally stabilizes there. The evolutionary law of the WCFZ shape obtained by physical simulation is basically consistent with that of numerical simulation. The fracture-mining ratio calculated by empirical formula ranges from 10.6 to 16.2, the value obtained from physical similar material simulation is 10.46, and that from numerical simulation is 16.63. Field measured data indicate that the final vertical height of the water-conducting fracture zone reaches 150.81 m, corresponding to a fracture-mining ratio of 16.67. This result is in good agreement with the upper limit of the empirical formula calculation and the numerical simulation result.