Abstract： No.1523 Face was located in the fifth mining area of the south wing of Gequan Mine. Through the analysis of comprehensive geophysical prospecting and drilling data before mining, the hidden collapse column was not developed in the working face, but No. X503 collapse column was exposed in the actual mining process. In order to ensure the safe mining of the working face through the collapse column, when the working face was mined to the collapse column, the water injection slurry reinforcement was carried out 10 ~ 40 m below the floor of No.2 coal seam of X503 collapse column in transportation roadway. The safety evaluation was carried out from three aspects : drilling grouting effect, water source analysis in collapse column and water inrush coefficient of floor after grouting. After drilling grouting reinforcement, an effective aquiclude had been formed in the 10-40 m section under No.2 coal floor in X503 collapse column, and there was no deep water supply such as Ordovician water in collapse column. Therefore, it was determined that No.1523 working face could be safely mined through No. X503 collapse column.
