| Rock-burst is one of the most typical rock or coal dynamical disasters in coal mine. Withthe increase of depth, many mine gradually towards deep mining so that productionconditions continuously deteriorate, which causes rock-burst more and more serious,especially rock-burst dynamic disaster of downhill roadway protection coal pillar area of coalseams and double wings combinined in deep mine is more outstanding and complicated anddestructive, and the relative study is less. Therefore, the paper explore the mechanism andprevention technology systems of rock-burst which occurres in downhill roadway protectioncoal pillar area with the depth over1000m by some methods including theoretical analysisand numerical simulation and field practice.The paper studys and explores the overlying strata structure evolution feature and stressdistribution law and rock-burst mechanism in downhill roadway protection coal pillar areabased on related theories. It successively experiences “F” structure of Single seam miningone side and “T” structure of single seam mining both sides and large “T” structureoverlying strata evolution of coal seams mining both sides in downhill roadway coal pillararea, which causes rock-burst hazard continuously increase. High stress concentrates andoverlying strata moves violently in downhill roadway coal pillar area. Rock-burst is inducedby dynamic load of strong mining tremors and high static load superposition in downhillroadway coal pillar area of deep mine.Using FLAC2Dnumerical simulation software analysis static load and dynamic load andprotection layer mining in downhill roadway coal pillar area. Wherever static load or dynamicload function, the roadway stress and displacement and plastic area all increase nonlinearlywith the decrease of coal pillar width which causes rock-burst hazard continuously increase sothat we suggest the distance between face stopping line and downhill roadway is at least100m in deep mine. The roadway dynamic response characteristics under dynamic loadfunction are both stronger than the effect of corresponding static load function which causesrock-burst hazardis of coal seams mining higher. Up protection layer mining can reduce stressconcentration degree of protected seam roadway and increase floor heave displacement andplastic area, in which the effect of rock-burst prevention is goodApplicating SOS micro-seismic monitoring system studys mine tremors rules indownhill roadway coal pillar area. Mine tremors events especially large energy strong minetremors mainly distribute in downhill roadway coal pillar area. With working face mining,quantity and energy of mine tremors continuously increase in coal pillar area. Disturbanceinfluence of face mining in the whole coal pillar area is bigger than the effect of face mining on itself. Mine tremors mainly concentrate in100meter range of roof and floor rocks, and themine tremors of roof are more than what distributing in floor. There is some difference amongmine tremors wave form and spectrum signature of different energy level which mainlymanifestes as“high frequency and low energy, low frequency and high energy”.Regarding-1025west downhill mining area in Zhangxiaolou caft of Pangzhuang coalmine belonging to xuzhou mining group as field background, the paper takes comparativelyperfect locality measures which prevent and control rock-burst during tunneling and mining indownhill roadway coal pillar area, which mainly makes pre-unloading treatment by largediameter drilling and roof and floor bursting before extracting and takes danger-breakingmeasures by coal bursting based on monitoring results during extracting and strengthensrock-burst warning and governance of other roadway groups in coal pillar area with goodsituational effect. Meanwhile, the paper makes optimization design of rock-burst preventionin deep mining areaThe research can provide theoretical support and technical guidance for safety mining ofsimilar conditions coal mine. |
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