Most of existing comprehensive exploration technologies for water-hazard on coal mine working face adopt conventional rotary drilling method with lots of boreholes and heavy workload. In addition, blending deformation of drill pipes, geological condition variation in boreholes and alterations of drilling parameters during construction process would lead to borehole deflection, which may cause wrong decision about water-hazard exploration. For above problems, a comprehensive exploration technology based on directional drilling was proposed and applied to water-hazard detection on fully mechanized mining face of a coal mine. The application process is as follows: Firstly, mine audio-frequency electric penetration technology is used in the comprehensive exploration technology to detect anomalous area with low apparent resistivity on the working face, and then directional drilling technology is adopted to directly expose water-rich zone. It is determined that there is a water-conductive collapse column of Ordovician limestone karst in the anomalous area through observing water gushing in the boreholes and chemically examine quality of the water. Meanwhile, extension state and boundary of the water-conductive collapse column in the working face are delineated. Position of open-off cut is redesigned according to comprehensive exploration results, so as to effectively eliminate hidden water-inrush danger caused by exposing the water-conductive collapse column during mining process.
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