Numerical Simulation Study on Stability Control Technology of Large-Area Wall Caving Area (LAWCA) in Large-Inclined Face

The caving characteristics of the goaf significantly impact the mining stability of the working face. The coal-forming environment of the steeply dipping coal seam is complex. After mining, the caving rock mass rolls to the lower part of the working face due to gravity, and the caving compaction characteristics of the working face are different from those of the flat and gently inclined working face, taking Huainan Xinji No. 2 Mine 211112 high-angle composite roof working face large-area gang roof fall area as the engineering background. To safely pass through a large roof fall area, a FLAC3D numerical simulation method considering the goaf's compaction effect and the excavation's additional damage is proposed. The Weibull distribution function is introduced to modify the elastic modulus parameters of the rock mass after excavation, which more accurately reflects the damage process of the rock mass after hole. Based on the goaf compaction theory, the elastic model is developed for the second time, and the accurate simulation of the caving rock mass is realized. On this basis, the proposed numerical simulation method is used to simulate the large-area roof caving of the large-angle working face, a scheme to control the stability of the working face by using the paste filling technology is proposed, and the material parameters of the filling body are determined. The research results show that when the water-cement ratio of the backfill is 3 : 1, the simulation and field trial results are good, and the safe and efficient mining of the large-angle composite roof working face is realized, which verifies the feasibility and correctness of the coupled simulation method. At the same time, the research results can provide a reference for controlling the roof fall area of the working face with a large inclination angle.