Research on comprehensive supporting technology of roadway under overlying close distance residual coal pillar
In order to solve the problem that the excavation deformation of the underlying roadway is large and the original supporting scheme cannot effectively control the deformation of the surrounding rock under the action of the overlying residual coal pillar under the condition of close distance,taking the machine-rail integrated roadway of No.5303 working face of Shaqu No.2 Coal Mine as the engi-neering background,the theoretical analysis,numerical simulation and on-site mine pressure monitoring were used to analyze the load transfer law from the residual coal pillar of the overlying goaf to the coal and rock mass of the floor.The failure characteristics of the floor under the mining action were studied,and the comprehensive supporting technology of the roadway in the affected area of the over-lying residual coal pillar was proposed.The results showed that the residual coal pillar area caused obvious stress concentration in the coal seam floor,based on the plastic slip line field theory,the failure depth of the floor was 6.38 m,and the machine-rail integrated roadway was at the edge of the failure depth.The comprehensive supporting scheme of roadway head-on anchor cable supporting+lag roadway roof truss anchor cable reinforcement supporting and single hydraulic prop+Π type steel beam strengthening supporting was proposed.Numerical simulation and on-site mine pressure monitoring showed that the displacement of the roof and floor of the roadway and the deformation of the two sides were 210 mm and 151 mm,respectively,and the top bolt and anchor cable force were 142.4 kN and 245 kN,respectively,both within a controllable range.This technology provides reference for roadway supporting under special condi-tions such as tectonic influence zones and high stress zones.
close distance coal seamresidual coal pillarstress concentrationfloor failurecomprehensive supporting