Abstract: Although the 1312 face in Zhangcun Mine took place intermittent water flush during mining, the height of water fractured zone don't develop to aquifer by empirical formulae. By analyzing hydrogeology conditions from the direct roof of 1312 face in Zhangcun Mine and using RFPA and actual detection to study the law of fractured full-mechanized Caving mining. Results shows that: ①According to the empirical formulae, the max height of water fractured zone is 45~58 m, which is greatly different from the RFPA result (95 m), and the major cause of the higher height of coal-series strata is the thin inferior key strata in direct roof as well as distance to 3 seam less than 58 m; ②The height of water fractured zone is about 96 m by actual detection , which is agreement with RFPA result; ③The spatial position of key-stratum and aquifer determine discontinuous water inrush and lag water inrush will happen in working face.

Key words: Water fractured zone, Key stratum, Lag water inrush, RFPA