Abstract: The development and expansion of water flow fracture zone in coal mine plays an impor⁃ tant role in safe mining. Taking Yuandatan Coal Mine as an example，in order to achieve the goal of protect⁃ ing groundwater system while coal mining，three detection boreholes were carried out，and the develop⁃ ment and expansion of water flow fracture zone in coal mining face were judged by using the consumption of drilling flushing fluid. The results show that the fracture zone length of No.2 coal seam is 104.36~110.37 m. When the mining height is 3.2 m，the fracture-mining ratio is 32.61~34.49 m. The top of the water flow fracture zone is within the Zhiluo Formation，about 151~157 m from the bottom of the Cretaceous strata， and about 189~195 m from the bottom of the Quaternary Salawusu Formation. Mining did not cause distur⁃ bance and damage to the Cretaceous aquifer and the Salawusu Formation aquifer. The prevention and con⁃ trol of formation water in Zhiluo Formation within the development and extension range of fracture zone should be strengthened.

Key words: water flow crack zone, flushing fluid consumption rate, crack development extension, wa? ter preserving mining