Study On Strong Pressure Behavior Mechanism And Roof Control Of Fully Mechanized Top Coal Caving In Extra Thickness Seam In Datong Coal Mine

Datong mining area is Jurassic and carboniferous dual seam lines meanwhileoccurrence and is difficult to take hard roof mine, where the occurrence of coal seamand mining conditions is complicated, in the carboniferous special thick seam miningprocess, there has been a strong pressure behavior in the face but also seriously affectthe face safe and high efficiency production. So this paper combined with regionaltectonic features of Datong mine, occurrence conditions of two-line coal geological,existing mining environment and requires of carboniferous special thick seam safeand high efficiency production mining, applied theoretical analysis, physicalsimilarity simulation, numerical calculation and field measurement method ofcombining, in-depth analysis of strong pressure behavior mechanism of thecarboniferous special thick seam mining face, proposed control methods and technicalmeans for the face strong pressure.(1) Reveals the characteristic of Datong mining area carboniferous special thickseam mining face ground pressure behavior. Carboniferous3-5#special thick seam offully mechanized caving face shown the basic roof first weighting step and periodicweighting step are big, dynamic load coefficient is big, with strong pressure behaviorcharacteristics, roof pressure of long duration, stent valve opens frequently, coal walland the working face rock deformation seriously, dynamic load characteristicssignificantly, but also the strength of periodic pressure shown the cycle variation ofthe strength of alternating.(2) Based on geological dynamics and mining technical conditions from themacro to the micro local region established new ways. Revealed the geologicaldynamic environment of Datong mine, the mining interaction of double seam lines,and the mechanism of jurassic gob pillar stress concentration and carboniferous coaloverburden fracture, joint action along the empty dynamic multi-factor of strongpressure appearing.(3) Reveals the influence mechanism of Kouquan fracture to the strong pressureof Tongxin mine field. Where the horizontal compression and vertical movements ofKouquan fracture formation of the typical geological dynamic environment, thecomplex tectonic setting, stress concentration and accumulation of elastic energy thatformation of geological dynamic conditious of a strong pressure occurrenced, by thedivision of field tectonic stress areas, the geological structure and high-stress areas ofoccurrence strong pressure behavior were definited.(4) The mechanism of interaction of dual seam lines mining and effection ofjurassic gob pillar to carboniferous mining were analysed. The section pillar of Yongding village mine jurassic gob which is overlying Tongxin mine field leaving,which the stress influence depth is50~70m, when carboniferous coal seam miningthe height of overlying strata collapse crack is150-170m, the stress concentration ofsection pillar and the activities of overburden rock intensified pressure to pass andstrength of mine pressure behavior.(5) Reveals the structural characteristics of overlying strata collapse andinstability on carboniferous special thick seam mining, whereby establishment ofmechanics model between a special thick seam fully mechanized caving face and therelationship with the surrounding rock, but also determine the support resistancecalculated methods under the conditions of carboniferous special thick seam overlyingstrata multilayer hard roof.(6) Propose methods of reasonable selection of stent under the special thick seamof Datong mining area strong pressure behavior control and combined with auxiliarycontrol technology, establishment of control technology of a hydraulic fracturingweakened hard roof and high stress weakening, effectively reducing the strength ofmine pressure behavior and achieved significant technical results.