Research On Local Weak Support Effect Of Deep Roadway And Surrounding Rock Control Technology

With the development of coal mining’s depth, there are a series of complex problems, such as the high pressure in deep mines, the large deformation of roadway surrounding rocks, the serious development of the fractures in rock mass and the broken surrounding rocks of roadway.The problem of supporting and maintaining for the roadway in deep high stress soft rock becomes more and more conspicuous.Therefore,it has become an urgent problem to be solved about how to solve the support problem for all kinds of complicated deep soft rock under the high stress. It is very profound significant for the study on the deformation and failure features of surrounding rocks in deep roadway, the interaction mechanism between the supporting structures and the surrounding rocks, and the development of a new type of roadway supporting technology.In this paper, the RMT rock mechanics testing system and the high temperature and pressure creep tester are used. The basic mechanical properties tests and the creep tests of the surrounding rocks in deep roadway are done. The test data of rock creep are analyzed.It is obtained that the rules of the axial strain of rocks changing with time, the characteristics of visco-elastic plastic strain, the change laws of creep rate,and the effect laws of the confining pressure for rock creep.The studies show that the confining pressure have significant constraint effect on rock creep,and the fracture time of rock creep can be slowed down by the increase of confining pressure.The theoretical knowledge of elastic-plastic mechanics and rock mechanics are using to establish mechanical model of circular section roadway.Combined with the supporting characteristics of the soft surrounding rock,the distribution laws of the stress field and the displacement field for the surrounding rock in the entire roadway are calculated in the case of weak support occurred in the range of angle 2 β in floor. And the displacement and stress analytical solution of the roadway with local weak support are calculated. The three dimensional shell bolting shotcrete supporting structure is put forward,based on the theory of shell structure,the research on the open cylindrical shell is done.The thin shell structure model with the short column of hinged supports is set up and the expression of stress for shell structure is derived.The research shows that the mechanical property of the materials can be improved by the three dimensional shell bolting and shotcrete structure,which has the characteristics of the flexible pressure and eliminate the influence of local weak support,so that the overall stability of the retaining structure can be improved.The similar model tests of the monolithic three dimensional reticulated shell lining structure and the whole frame structure are done. For the structure of the model,the bearing capacity, the forms and the laws of development about the deformation and failure are analyzed.The test shows that the rebar of three dimensional shell bracket are in good stress,and the structure has a good linear relationship.The compressive properties of concrete can be given fully play to,which shows that the material properties can be given full play to by the supporting structure.The bearing capacity of the whole frame structure model is high.The roadway of the supporting section with the three dimensional shell bolting and shotcrete support structure was simulated by using the numerical analysis software Midas/GTS.The research shows that the overall deformation of the roadway surrounding rock is small,and the surrounding rocks are in the good state of stress.Three dimensional shell lining structure is in uniform stress,the rock stress concentration of roadway surrounding rock can be weaken, the stress distribution of the surrounding rock can be well improved and the displacement of the surrounding rock is greatly reduced, the bearing capacity of supporting structure is greatly improved.Three dimensional shell bolting shotcrete supporting structure is successfully applied in Panthsan mine test roadway of Huainan mining industry group,Processing mould of the shell bracket is designed, technical requirements for construction and processing technical specifications are formulated, the site monitoring and effect evaluation are completed.Engineering application indicates,three dimensional shell bolting and shotcrete supporting structure is a supporting structure of the novel structure, the excellent performance, the high supporting capacity,and the low cost.The integrity of the interaction between the surrounding rock and the supporting structure is good,the self stabilization time of the surrounding rock can be prolonged,it is conducive to play the bearing capacity of surrounding rock.It provides a new supporting technology for soft rock roadway, social results and economic benefits are significant.