Critical Assessment Of Water Inrush Under The Lower Coal Seam During Mining With Pressure In Yangcun Mine

Water inrush coefficient method is widely used in coal mining safety assessment underhigh pressure,because of the simple formula and the easily obtained calculation parameters.It isa traditional and effective method for the feasibility evaluation of coal mining with waterpressure and was written into "mine water control regulations" which was promulgated in2009.However, the critical value of formula is mainly based on the summary of numerous waterinrush coal mines such as Jiaozuo, Jingxing, Zibo and Fengfeng in the1960s.It should beconsidered whether it can apply to mine the lower coal seam of Yanzhou Coal Mines underpressure or not.In this paper, through collecting the hydrogeological data of Yangcun Coal Mine and the partof the group that has been mined, as well as basing on the theory of mine rock mechanics andmine engineering geology, the author analyzed the geological and hydrogeological parameters ofthe lower coal seam. Then, the deformation depth of mining floor of coal seam was got by thefield measurement in the selected working face, as well as the preventing seepage capability ofthe main floor rock.The results shows that the floor deformation depth of Yangcun coal seam fieldis10.1m. The floor unit impermeability strength values of different structure and lithologicalwere obtained by the water injection tests. Moreover, compared with Dongtan experimentalresults in Yanzhou Coal Mine, the threshold value of preventing seepage strength werecalculated, and the mining safety was evaluated used the ratio of aquifer water pressure withfloor preventing seepage strength.Finally, it is proved that the safety factor method can better reflect the actual situation of thefloor preventing seepage capability than water inrush coefficient method due to the result ofmonitoring process in2702working face.The safety factor can fully reveal the preventingseepage capability of coal seam floor and can provide technical support for floor water damageprevention in coal mining under pressure in Yangcun coal seam. Also, it is an importantreference for coal seam mining in Yanzhou mine and similar ecological conditions coal mines.