Abstract: In order to accurately predict the depth of floor damage caused by coal mining and effec⁃ tively prevent mine floor water disasters，ensuring the safety of coal mining production. Under the condi⁃ tion of close-range multi-coal-layer mining，in response to the key issue of floor damage depth prediction in the Nantun Coal Mine of Yanzhou mining area，based on a large number of engineering statistical laws and empirical formulas，the floor damage depth of the coal seam was calculated. Through the FLAC3D nu⁃ merical simulation software，a 3D geological mechanics model was established to systematically simulate the multi-coal-layer mining process of the working face，and to deeply analyze the stress evolution，plas⁃ tic zone distribution and damage depth change laws of the floor rock layer under mining disturbance. The re⁃ sults show that the empirical formula depth of the floor damage zone in the 11501 working face is 18.56 m and 26.52 m respectively. The numerical simulation shows that the floor damage depth increases with the advancement distance，the top and bottom plate stress increases，and stress concentration zones are formed at both ends of the mined area. When advancing 350 m，the damage depth reaches the maximum value (about 20 m)，and then stabilizes but expands the range; when advancing 100 m，the damage range decreases with depth，and the maximum depth is about 20 m. The empirical formula and numerical simula⁃ tion mutually verify each other，and both can effectively predict the floor damage depth，providing a reli⁃ able basis for the prevention of floor water disasters. This research provides important technical references for safe mining in similar geological conditions.

Key words: multi-coal-layer mining, floor failure depth, mine water hazard prevention, numerical simulation