Study On Strata-pressure Behavior In Fully-mechanized Face Of Zhouyuanshan Coal Mine

Recently, Zhou Yuanshan coal mine has carried on the beneficial exploration andpractice on the promotion of fully-mechanized mining technology, because of the coalmine which implement fully mechanized mining under the complicated geologicalconditions of the south is not very much, the successful cases of the similar conditions wecan draw lessons from is so poor. There are many problems in the exploration practice inthe process of fully mechanized technology, such as the strata-pressure characteristics andits control,applicable characteristics of hydraulic support in the complicated geologicalconditions, the influence of the mining parameters in working face on strata behaviors andits rationality and so on. Around these issues, a series of mine pressure observation wascarried out in mining process of the first fully-mechanized mining working face in ZhouYuanshan coal,related research on strata behaviors was carried out combine withtheoretical analysis and numerical simulation.Structural features of overlying strata and movement law of key blocks in miningwere analyzed through the key stratum theory and the key blocks “S-R”stability conditioncombining with the numerical simulation software UDEC,concluded that there’re threeinferior key stratas and a main key stratum in overlying strata,the maximum turningangleof key block is9.4°, key block meet the" R "type rotary instability conditions, theminimum working resistance of hydraulic support to control rotary instability of main roofis173.34KN/m~2; the numerical results of initial weighting interval and periodicweighting length are26.0m and11.3m,the theoretical calculation value is25.91m and10.6m,both are relatively similar.Strata behaviors observations show that the initial weighting length is24.50m,thedynamic pressure coefficient is1.72;the periodic weighting length is is10.3m, thedynamic pressure coefficient is1.62; The location of lead abutment pressure peak nearbythe upper part of working face is10~15m before coal wall and3~8m before coal wallnearby the lower part of working face. The significant deformation scope in sectiontransportation drift is25m before coal wall,the significant deformation scope in section airreturn drift is13.0m before coal wall,the developing depth of loose fracture zone in roofrock mass of section air return drift is2.03m,the depth in section transportation drift is0.21m. The floor specific pressure is9.4MPa,the roof falling sensitivity is74%.Applicable characteristics of hydraulic support is analyzed through mathematicalstatistics and data regression method,the results show that the utilization rate of workingresistance is0.389,design setting load utilization ratio is0.492,the working resistance extraamount of hydraulic support is too large and the setting load is serious low; In order toexert hydraulic support performance efficiently,the Setting load should be improved to25.3MPa. Large inclined angle of working face have serious impact on hydraulic support,mainly realized as serious partial load,long time to constant resistance type workstatus,affecting the effect of setting load on improving supporting performance ofhydraulic support.Based on the background of the realization of double-unit face mining undercomplicated geological conditions and the behind face advance the front face ofdouble-unit face in Zhouyuanshan coal mine, combining with field measurementresults,strata-pressure behavior law is analyzed through FLAC3Dnumerical simulationsoftware,concluded that the stress concentration factor of superposition abutment pressureand the alternate distance of double-unit face are meeting gauss function and therelationship between the distance from stress concentration area to face end and thealternate distance of double-unit face also satisfy the gaussian function;when thedouble-unit face on a straight line,the stress concentration factor of superposition abutmentpressure is minimum,when after face advance to a position the front face end is in thegreatest impact area of superposition abutment pressure,and full consideration should begiven to avoid this area when determining the reasonable alternate distance.