INTEGRATED INSITU TESTS FOR WATER INRUSH POSSIBILITY EVALUATION IN COAL SEAM FLOORS

In a single hole with multipurposes,the evaluation ability of waterresistance and confirming progressive intrusion height can be put in practice during the process of geostresses tests with the insitu hydraulic fracturing method in mining working faces or roadways. Test results in practice show that the abilities of the waterresistances of mudrocks,fine sandstones,middle sandstones,limestones are from large to small. The progressive intrusion heights are from small to large. The abilities of the waterresistances of strata in the floor Nos. 11, 10, 7, 8 of the coal seams are from large to small. The strata stabilities in the floor Nos. 8, 11, 7, 10 of the coal seams are also from large to small. Geostress tests with the insitu hydraulic fracturing method indicate that the original geostress states are SH＞Sv＞Sh. The directions of the maximum horizontal stress are from NE to NEE in this area. The water inrush critical index evaluation shows that the water inrush possibility is higher as the coal extraction into the550m level. Preventive measures should be undertaken earlier．