Abstract:In response to the reasonable value of the thickness of the goaf protection pillar in the stage open stope followed by filling mining method used in the Hongling lead-zinc mine, the stress and deflection changes of the protection pillar are studied through theoretical calculation. Using the FLAC3D numerical simulation analysis method, the stability of the thickness of the protection pillar under different working conditions is studied, and the optimal thickness of the protection pillar is finally determined. Research shows: (1) According to the deformation theory of pressure bar and the calculation of ultimate deflection, the maximum deflection decreases with the increase of wall thickness. And the optimal thickness of the protection pillar is 3m. (2) According to the simulation analysis, the thickness of the protection pillar should be more than 3m, in order to better ensure the safety and stability of the protection pillar. (3) The z-direction stress curve of wall thickness an inverted "U" type distribution, and the maximum stress is concentrated at both ends of the protection pillar, which is similar to the theoretical stress distribution. This study provides a theoretical basis and analytical method for selecting the thickness of protection pillar in similar mines.