Paste Filling Technology and Its Application in Fully Mechanized Caving Mining Under Aquifer

In view of the problem that water inrush is easy to occur in the mining of coal seam under aquifer, taking a mine in Shaanxi Province as an engineering background, this paper proposes a paste filling technology behind transitional support in fully mechanized top-coal caving mining, expounds its technical principle and technological process, and analyzes the development characteristics of water-conducting fracture zone in back-support filling mining and the variation laws of water inflow in working face by means of numerical simulation and field observation. The numerical simulation results show that the water-conducting fracture zone of the working face develops into a rectangle with a maximum height of 67.2 m after the backfilling technology is adopted. The field observation results show that the filling rate after support can reach 90%, the water inflow of working face decreases significantly from 220 m³/h to 90 m³/h, and the maximum development height of water-conducting fracture zone is 76.8 m after 200 m advance of working face. The research results show that the technology can effectively reduce the height of water-conducting fissures in overburden and realize safe mining of extra-thick coal seam under aquifer.