1.School of Resources and Safety Engineering,China University of Mining and Technology(Beijing)，Beijing ,China;2.Mine Safety TechnologyBranch,China Coal Research Institute,Beijing ,China; 3.State Key Laboratory of Coal Mining and Clean Utilization,Beijing China

In order to obtain the formation mechanism of high pressure and low water permeability in coal seam roof,the overall technology of geophysical exploration,drilling and geochemical exploration was proposed as an auxiliary mean,and the solid-liquid-gas three-phase coupling characteristics were studied.The results show that the top rock strata lithology is a combination of soft and hard alternating rock layers,which is conducive to the occurrence of the top water in the aquifer,and it is difficult to replenish between the upper and lower aquifers; the influence of fault zone changed the distribution of the regional stress field and destroyed the equilibrium state between the original seepage field and stress field of the rock mass,which led to the deformation of the rock mass,increased the fragmentation of the rock mass and large rock mass fissure,resulting in a fault zone with better water storage capacity and groundwater permeability; because the rock mass is a multi-phase material composed of solid,liquid and gas phase,it is concluded that the high pressure in the roof is the mixing pressure formed by the synergy of water pressure,air pressure and high differential gravity.Through the engineering examples,the "three exploration" overall technology has been effectively applied to determine the importance of mine water damage prediction.

国家科技重大专项资助项目(2016ZX05045001-004)；国家自然科学基金资助项目(51674142)