Research on reasonable width and optimal design of anti-punching coal pillar based on GDEM simulation

In order to realize the safety of anti-punching during the working face back-mining period and to improve the safety and efficiency of underground mining, taking the 3-3 coal seam of a coal mine in Toksun as the engineering background, theoretical analysis, numerical simulation, and measured data are applied to analyze the coal body stress and overburden displacement in the three cases of leaving 15 m, 35 m, and 50 m coal pillars between the two working faces, and the measured microseismic data of the latter two cases are also compared. The theoretical analysis results show that stress concentration coefficient of coal pillars decreases with the increase of the width, and the impact risk can be effectively reduced by setting coal pillar with a width of 50 m. The results of numerical simulation and measured data show that the stress concentration degree of coal pillar with 50 m width is lower, which is beneficial to the safety of goaf. The displacement of the key strata under the 50 m coal pillar is smaller than that under 15 m and 35 m coal pillar, with a decrease of 11.8% and 7.6% respectively. When the width of coal pillar increases from 35 m to 50 m, there is basically no large energy microseismic event above the goaf. To sum up, coal pillars with a width of 50 m can effectively prevent rock burst, but excessively wide coal pillars cause resource waste. Filling mining can be used to optimize its design, and the numerical simulation results show that this method can effectively reduce coal body stress and overburden displacement. The conclusions can provide reference for other mines with similar geological conditions.