Study On The Key Factors Of Water Inrush During Mining Under The Unconsolidated Confined Aquifer Of Hydrogeology And Engineering Geology

This paper analyzes the17cases that unconsolidated and confined aquifer water through the roof into the working face in Qidong coal mine since it go into production.Though they set the waterproof pillar enough in accordance with the relevant procedures, these working faces still had water inrush Through comprehensive analysis, draw a conclusion that under the high pressure of unconsolidated aquifer, there are two key hydrological engineering geological conditions which leading the roof water inrush in working seam:Firstly, large thickness of high pressure unconsolidated aquifer, water content and pressure may cause underlying coal mining working face roof water inrush. Secondly, coal seam roof lithology with large thickness and mechanical strength of the hard rock, the effect of high water pressure unconsolidated aquifer lead to abnormal development of the fractured and caved zones of mining coal.Based on part of fractured rock mass damage mechanics theory, studied on the native crack expansion mechanism on the condition of high pressure water of unconsolidated aquifer directly covered on bedrock weathering zone, corresponding calculation formula is deduced. Primary cracks and expansion of bedrock by hydraulic pressure and depth of infiltration zone is security hidden danger on waterproof pillar. Statistics of native cracks in7131-3borehole bedrock weathering zone sampling, and calculate the depth of10.2m. The mining area water mining grade were divided, the fourth aquifer of near taniguchi of Valley alluvial fan-Middle ancient alluvial channel was class I water; the fourth aquifer with small thickness of floodplain sedimentation type was class II; close to the fourth aquifer working face coal seam containing according to "coal mining regulations" to set waterproof coal rock pillar, and the infiltration zone bottom as the bottom of aquifer boundary.In7131working face in the study area, reference to "Buildings,water,railway and coal pillar and coal mining regulations" theory of empirical formula to calculate the height of71coal seam in the fractured and caved zones.In order to meet the safety of waterproof coal rock pillar of coal seam mining height, limitation is3.4m, refer to the mining height, fractured and caved zones height is46.87m. Using FLAC3D numerical simulation software, working face with hard rock interaction structure model is established, were affected by the unconsolidated confined aquifer under the pressure of fluid-solid coupling simulation, get the seam mining fractured and caved zones height is53m, higher than the result of7131working surface hydrological and engineering geological conditions theoretical calculation. Simulation result is consistent with the three zones validation hole actual situation, and can be used as working face waterproof pillar basis.