THE REASON CAUSED FLOOR-HEAVE OF DRIFT AND ITS PREVENTIVE MEASURES AT 1178m SUBLEVEL OF No.2 MINE AREA IN JINCHUAN

When the develop project of 1178m sublevel in center and west part of Jinchuan No.2 mine area is developed,floor-heave and deformation of drifts are occurred.The paper analysis the reason of internal and external factors of the floor-heave,and the reasonable and effective preventive measures are proposed,it have a significant reference value for the construction of drifts in the future.