Simulation Study On Surrounding Rock Stability Of The Hardtop Coal Roadway

In some mining areas, the most rock in immediate roof is heavy sandy layers.In the past decades of years, Some measures have taken to the hard top coal roadway,adopting the wood, wood shed or the mixed shed to support roadways,and these measures could meet the need of safety mining. However, as the depth of mine is increasing continually and The effects of the pillar remained in upper mining area,geological structure as well as other factors, in parts of runnels,the phenomenon of soft rock began to appear,such as roadway extracting, ground swelling,lane caving. Owing to hard roof strata, coal side become the weakest place in the surrounding rocks, the accumulative energy in rocks release in the weakest place, pressurization of the roadway’s sides is violent,the broken area is larger than anchorage range in the Roadway’s Sides.If not well controlled, it would become a vicious circle.this paper studies stability of the hard top coal roadway, the authors put forward some suggestions to roadway support under new situation.According to the conditions of the soft roadway’s sides and stable roof of the hard top coal roadway, theory of loose ring and the whole anchorage support theory were used. Using mechanism of middle loose ring and suspension for hard roof, bolt support parameters were given.Using theory of loose ring for soft roof,the mechanism of thickness wall and arching play a major role. Anchor geometric parameters were analyzed, mechanical model of the roadway’s sides was established, some mechanical parameters of bolt support were given. According to stability problem of the hard top coal roadway,this paper adopts physical simulation experiment and uses experiment table of large proportion and plane strain model made by ourselves, test plan was established, we also use stress box made by ourselves,strain gauge and camera.the destroying and developing process as well as failure mode of roadway with stepwise loading has been simulated.we recorded and analyed law of stress change and deformation of surrounding rock,detected changes of plastic ring.this paper can supply theory and instruct production practice under similar geological conditions.Simultaneously, considering similar simulation is difficult to accurately depict failure and destruction line of rocks, numerical simulation method was used as supplement.this paper analysis change law of stress and displacement detailedly with numerical simulation.Finally, with the results of theory analysis,physical simulation and numerical simulation,this paper put forward supporting scheme and discusses why it is feasible with numerical simulation method.