Research On Stability Mechanism Of Coal Pillar And Stability Of Surrounding Rock Of Driving Roadway Along Gob In Closed Distance Seam Group

This graduation thesis take Shanjiaoshu Mine21156working face as theengineering background, according to the greater deformation situation after the21156return airway excavation, by combining the method of theoretical analysiswith numerical simulation and spot test, giving system study to stable mechanism ofclosed distance coal seam gob-side entry driving coal pillar, and the achievement isas the following:(1)This paper by means of analysis the stress distribution of gob-side entrydriving coal pillar, build coal pillar mechanical model. Using limit equilibriumtheory calculate and derivate plastic zone width computational formula of along gobarea coal body, and obtain reasonable coal pillar width theoretical computationalformula through the width computational formula of roadway surrounding rockplastic zone.(2)After analysis the coal body basic characteristics of closed distance coalseam group, using the method of theoretical analysis and numerical simulation, fromroadway surrounding rock properties, upper and lower coal seam mining and uppercurtate working face mining three aspects analyses its influence on coal pillar. Theresults show that: when the roadway surrounding rock properties is harder (includingthe roof, coal pillar, bottom), the deformation of coal pillar edge is smaller, thenuclear area inside of coal pillar is larger, and have a positive effect on the coalpillar stability; upper and lower coal seam mining has great influence on the bottomplate and the overlying strata, destroy the integrality of bottom plate and theoverlying strata, reduce the carrying capacity of the rock; with the condition of mainroof deformation given, when the upper curtate working face mining faster, make thelarger lateral span of coal pillar overlying main roof key block B, the greater ofdisplacement loading lower strata.(3)From the theory analysis and numerical simulation, bolt and cable couplingsupport technology has been adopted to maintain roadway. The principle of couplingsupport has been analyzed thoroughly, and the second support opportunity has beenanalyzed by numerical simulation methods, that improve support effect when thesecond support has been used in the inflection point of speed of roadway deformation.(4) Based on the engineering geological features of ventilation of21156working face in Shanjiaoshu mine, and according to the design ideas of couplingsupport, the support parameters were optimized rationally and applied to field test.The research result has been applied to ventilation roadway successfully.