Study On Supporting Mechanism Of Flexible Formwork For Soft And Broken Surrounding Rock And Its Practice

This dissertation studies the flexible formwork and concrete roadway support theory,including the anchored crown anchor combined supporting principle and buffer layer combinedsupporting principle, according to the actual geological conditions, puts forward the reasonablesupport parameter design method and production line, for the future application of flexibleformwork and concrete roadway supporting technology provides the theoretical basis anddesign method. The content of this paper is solving this problem, the technical route andinnovations. According to the research content, determined by theoretical study, numericalanalysis and in-situ test, combined with the research method of the monitoring system of fiberBragg grating. Through the research and practice the following results obtained：The first,according to the rock of combined beam theory, combination arch is a layer of alayer, body, roof bolt action, one is the friction between the anchoring force of strata and crownlayer, prevent sliding along the two layer, the two layer to avoid separation phenomenon; on theother hand, the anchor rod body can increase the shear stiffness among strata, prevent wrongamong strata moving, so the strata and crown layer anchorage range bolt of locking into a thickcomposite beam. Combined arch with flexible formwork arch formed concrete compositebeams, the bending moment is the only flexible formwork and concrete arch support moment0.063times, at this moment, greatly flexible formwork and concrete arch reduction, flexibleformwork and concrete supporting structure greatly improves the overall stability. Rock archbeam Yu yan arch laminated beam and flexible formwork and concrete arch with maximumtensile stress, reduced by11times, the bending moment is reduced by93%, large bearingcapacity increase.The second,soft mould pump note concrete support and concrete block Xuan build by laying bricks or stones compared with good stability, supporting capacity big, construction isconvenient, labor intensity low, construction speed etc; Fiber template filter water action andadmixture dispersion effect form self-compacting concrete, saving vibro process, improve thestrength of concrete at the same time for pumping concrete mechanical work provided acondition; Pump note concrete high mechanization degree, and construction speed is quick, acasting large thickness, high strength concrete, no rebound, no dust, and ensured theconstruction personnel health. In China using inorganic chemical anchoring agent, its materialand soil close, bonding effect is good, than resin anchoring agent and reliable, and easyinstallation, low cost, Soft mould pump note concrete support is a new type of rapid supportingmethod, suitable for Philippine coal mine soil conditions and the requirements of rapidconstruction safety.The third,fiber grating system can monitor the bolt axial force, reflected the change ofsurrounding rock pressure flexible formwork and concrete supporting process, support changesin the structure of the force, the axial force of bolt experienced increases in supporting process,and then decreases the final stable state. Bolt axial force on the flexible formwork and concretesupport6to7days after supporting peak, the maximum11.2kN, basically stable at20dayslater, and smaller stress, maximum8.42kN, flexible formwork and concrete arch in supportingwith bolt joint bearing, the supporting structure stability.The forth,rock arch composite beam theory calculation were not considered in theconnection of combined arch and flexible formwork and concrete arch bolt strength, stiffness,density, the simulations also had no effect on the anchor geometry size and different layout offlexible formwork and concrete arch bending moment of comparative studies; the anchorcombined support of buffer layer protecting just discussed earlier theories, there are manyproblems need to be further study and work to continue to explore and research.The fifth,in engineering practice,employ fiber bragg gratings monitoring system and laserdisplacement real-time monitoring system to monitor supporting quality of the flexibleformwork and concrete roadway supporting structure,analyse deformation of flexibleformwork concrete roadway supporting and the stress of the bolt.Fiber bragg gratingsmonitored the bolt axial stress,reflects the variation of the surrounding rocks stress in flexibleformwork and concrete roadway supporting.The bolt axial stress increases first,thendecreases,finaly gets stable in the supporting period.Monitoring demonstrates that the flexibleformwork concrete masonry bears the load with bolt,the whole supporting structure becomessteady.The end,research achievement put into use in Hongliu mine gentle slope inclined shaft supporting construction,in service period,the roadway needs no maintain,satisfy themanufacture requirement,attains remarkable technology and economic benefits.