Numerical Simulation and Analysis of Influencing Factors of Coal Wall Failure in Fully Mechanized Mining Face with Large Mining Height

Aiming at the problems that the coal wall rib spalling in the working face affects the economic benefits of fully mechanized mining technology with large mining height, the 3-1 coal seam occurrence conditions of Hongqinghe Coal Mine is taken as the research background. The orthogonal experimental scheme was designed and simulated by the FLAC^3D software. Based on Drucker-Prager criterion, the failure coefficient of the mining face was calculated. Five factors affecting the coal mining face failure were studied. Conclusion were drawn as follows, some measures can increase the extent of the coal mining face failure, such as increasing the burial depth and the distance between the focus of the support force and the mining face, extending the length of working face and the mining height; improving the support force can reduce the rib spalling. The rank of five factors by influence degree is as follows: burial depth>the distance between the focus of the support force and the mining face>the support force>the mining height>the length of working face. The reasonable process parameters of the 3-1 coal seam mining are given: the mining height is 6.2 m, the working face length is 225 m, the distance between the joint force and the coal wall is 2 m, and the initial support force of the bracket is 12 000 kN.