Study On Supporting Technology And Failure Mechanism Of Arch Roadway Spandrel In Bedded Rock Mass

Coal measure strata is bedded rock mass that formed by sedimentary rock, with the rapiddevelopment of our industry, the demand of basic energies such as coal is increasing, roofcontrol problem during roadway excavation at bedded rock mass. Arched section form hasobvious advantages in mechanics, but excavation of arch roadway in bedded rock mass,because of rock property difference, uneven loading and deformation incompatibility, failureusually occurs at arch roadway spandrel. Thus, to clearly analyze deformation and failuremechanism of arch roadway spandrel in bedded rock mass, to choose reasonable section formin bedded rock mass, and to study supporting technology have important engineeringapplication values. The paper separately simplified rock mass at arch roadway spandrel inhorizontal and banked bedded rock mass to cantilever model, further studied deformationand failure mechanism of arch roadway spandrel in bedded rock mass by combinating oftheoretical analysis, numerical simulation and field test, the main conclusions were asfollows:(1)By analyzing stress state of arch roadway roof in bedded rock mass, and combinatingwith current researches of bedded rock mass roof, systematically generalized and summarizeddeformation and failure characteristics of bedded rock mass roof in coal mine roadway.(2)Simplified rock mass at arch roadway spandrel in bedded rock mass to cantilevermodel, by analyzing stress states of three layers of adjacent rock mass, considered frictionbetween layer and layer when flexural deflection of terrane, iterated the pressure values andtheir transitive relations of each terrane bore from its covering layer. The paper iteratedcomputational formula about horizontal stress o f bedded rock mass iterated, judged eachterrane and determined the specific location where failure occurred. By instance’s calculateanalysis of horizontal bedded rock mass at HeCaogou Coal Mine and banked bedded rock mass at WuLan Coal Mine, the results were agreed with actual field conditions, concludedthat caving failure is easily occurred at arch roadway spandrel in bedded rock mass.(3)By analysis on failure mechanism of arched section roadway and rectangular sectionroadway in bedded rock mass, the paper found that except ground stress, the physical andmechanical properties of surrounding rock, surrounding rock structures are the factors whichaffected the stability of roadway in bedded rock mass, the section form of roadway is a greatfactor. The paper put forward that flat rectangle section used in horizontal bedded rock massand rounded trapezoidal cross-section used in banked bedded rock mass are in favor ofstability of roadway.(4)Based on deformation and failure mechanism of roadway surrounding rock in beddedrock mass, the paper studied the reasonable supporting technology of roadway in bedded rockmass. Supporting parameter of bolt is determined by combination arch supporting mechanism.The length and density of bolt and supporting parameters of anchor is determined by thedeformation (failure) range of coal surround roadway, value of the load which exerts on boltsupporting and the bearing capacity of anchor combined bolt. Design of dynamic informationis adopted during roadway supporting design, by preliminary support design, stabilitymonitoring, supporting effect evaluation, supporting parameters optimization and the processof the roadway drivage supporting, a system of design method about supporting parameterswhich is fit for bedded rock mass is put forward.(5)Based on5#return airway (horizontal bedded rock mass) at HeCaogou Coal Mineand5249transport trough (banked bedded rock mass) at WuLan Coal Mine, the paperadopted numerical simulation to test and verify the choice of roadway section in bedded rockmass and the reasonable supporting technology that put forward.