Abstract: Based on the theory of controlling height of mining-induced fracture by gangue backfill mining, the software FLAC3D is used to study the change law of height of water flowing fractured zone. Calculation model of height of water flowing fractured zone between mining height and compaction ratio is gained by the means of multiple linear regression. The determination method of mining upper limit under aquifer is proposed. The results show that the mining upper limit can be extended from -300 m to -255 m and 1.826 million tons coal resources can be recovered on the condition of mining height less than 3.5 m and compaction ratio up to 85%. Through the test of gangue backfill mining in Wugou coal mine, the height of water flowing fractured zone is just 10 m by the leakage volume of drilling fluid. The monitoring results are quite consistent with the theoretical calculation.

Key words: aquifer, gangue backfill mining, compaction ratio, mining upper limit, water flowing fractured zone