The Effects Research On Outburst Elimination Of Hydraulic Flushing And Scheme Optimization In Shoushan Mine

The coal seam occurrence conditions of Coal Seam J15-17Shoushan-yi mine are high gaspressure&content, soft coal, poor permeability, serious orifices. Thus, the gas drainage effect wasIneffective by practice. As one of pressure releasing and increasing permeability measures,hydraulic flushing can increase the permeability and gas drainage efficiency, decrease gas pressure&content, enlarge the distressed zone. So, the probability of coal&gas outburst can be eliminatedin coal drift driving zone in this way, safe and fast tunneling also can be achieved for drilling workamount decreased and drainage time shorten. According to theory analyzing and site testing, CoalSeam J15-17of Shoushan-yi mine1is suitable for hydraulic flushing and some correspondingfeasibility parameters are obtained. Jet nozzle type is1φ1.8+2φ4mm and flushing pressure is4~6MPa.The reason for stress releasing and permeability increasing in coal seam caused byHydraulic flushing is high-pressure water jet compressing coal structure to crushed, and conveyinglarge amount coal cinder.Under the gas pressure and crustal stress combined action, coal’s size ischanged, with fracture amount and permeability increasing. To be accoMPanied by the gasemission, coal size becomes contraction, stress concentration moves to deep part, at the same time,a stress-released is forming. Gas-solid partial differential equation of gas in stress field andseepage field during hydraulic flushing is established based on coal state under stain an-d gasdelivery following the mass conservation law. The equation consist control equation of coaldeformations,coal delivery continuous equation, cross-coupling relation equation. Gas deliveryunder coupling-physics field is affected by geostress, coal deformation degrees andpermeability.Combining site testing and software of COMSOL-Multi-physics successfullysimulates gas pressure and coal stress variation corresponding to different hole, and the effectiveradius and distance between holes after the same drainage time, optimize the flushing plan.Through a comprehensive analysis of coal stress and gas drainage effect, the effective radius is4-7m, coal mass1t/m, max distance between holes is8m.