Study On Deformation And Failure Law Of Tunnel Caused By Ground Stress And Countermeasure Of Support

With the rapid development of geotechnical and underground engineering in our country,all kinds of engineering problems are getting worse,because of the complexity of underground engineering,the problem of deformation,failure and support of underground tunnel has been a difficult problem,the stability of the roadway is the precondition to guarantee the economic,safe and efficient construction,and the crustal stress is the fundamental force causing the deformation and destruction of various open and underground rock and soil excavation works,therefore,it is of strategic importance to study the failure rules and support measures of roadway caused by crustal stress.In order to study the deformation and failure regularity of roadway caused by crustal stress and its support measures,taking the HouPing mine of XingFa group as the engineering background,the following work is carried out: 1.to find out the laws of roadway deformation caused by crustal stress at home and abroad as well as the related research of support results,summarizing the collected data;2.field investigation and sampling are carried out to carry out uniaxial,three axial and split tests on various rock types in the laboratory,rock mechanical parameters are determined and rock failure mechanisms are studied;3.theoretical analysis of surrounding rock stress is carried out in different sections(round,straight wall and round arch,rectangular),and the deformation and failure rules of roadway are studied;4.using FLAC 3D to carry out numerical simulation of the roadway in HouPing section,and study the deformation and failure law of the roadway under different stress field(different lateral pressure coefficient);5.to optimize the design of the roadway support in the HouPing mine and put forward the supporting proposal.Through research,the following results are obtained: 1.HouPing mine rock generally has high elastic modulus,large elastic deformation,high bearing capacity,small deformation modulus,and shaping is not obvious,once destroyed,it will lost rock bearingcapacity,and make great noise,it is disintegrated after crushing,so it belongs to the typical hard brittle rock;2.the destruction of rock is the result of macro cracks formed by the expansion and coalescence of microcracks within the force,judging from the destruction of phosphate rock in the interior,most of the phosphate rock break along the crystal interface between dolomite and phosphate rock,it explains that the crystalline interface between dolomite and phosphate rock is weaker than dolomite and the crystalline interface between dolomite and dolomite is weaker than that between phosphate rock and phosphate rock;3.through theoretical analysis of surrounding rock stress after tunnel excavation,tunnel surrounding to the depths are formed from the broken zone,plastic zone and elastic deformation zone,the original rock stress zone,the deformation and failure of the roadway are related to the lateral pressure coefficient and the size of the tunnel;4.through the numerical simulation of the excavation deformation of the tunnel in the HouPing section,it is found that for the roadway at the HouPing mine,under different stress fields(?=0.25?0.5?0.75?1?1.25?1.5?1.75?2?2.25?2.5 ? 2.75 ? 3),the deformation of the floor is greater than that of the roof,and the deformation of the roof and floor is much greater than that of the deformation of the side,when ?=0.75,the roadway floor deformation is minimal,and the roof deformation is the biggest,When ?=1,the deformation of roadway floor is maximum,and the maximum principal stress is in the floor,When ?=2,the roof displacement of roadway is minimum,When ?=3,the maximum principal stress value is minimum,and the plastic zone of tunnel is mainly distributed in the top and bottom of roadway,and the plastic zone varies little with the increase of lateral pressure coefficient;5.some suggestions are put forward for the support of the HouPing roadway: the top and bottom are supported by bolting and shotcreting,and set "anti arch" at the bottom plate,while the anchor bolt and shotcrete support are used in the side.