Analysis Of Collapse Characteristics Of Soft Surrounding Rock Tunnel Based On Model Test And Numerical Simulation

With the rapid development of China's transportation network construction,the number of tunnel construction is increasing.In recent years,major accidents such as tunnel surrounding rock collapse have been reported in the tunnel construction process,and there are many landslide accidents in the soft surrounding rock tunnel.The landslide accident will not only affect the construction period of the tunnel construction,but once the tunnel collapses,it will cause huge losses to people's lives and property.The causes of tunnel collapse mainly include poor geological conditions of surrounding rock,unreasonable construction methods,and intensified support measures for weak locations of surrounding rock in time.Because the rock strength of the weak surrounding rock tunnel is low,the CRD method can quickly form a tunnel.Therefore,in order to ensure the safety of tunnel construction,in the actual project,the excavation of the weak surrounding rock tunnel is usually carried out by the CRD method.However,there are many construction procedures in the CRD construction method,which will cause multiple disturbances to the surrounding rock of the tunnel,affecting the stability of the surrounding rock of the tunnel.In severe cases,it will cause a collapse accident in the weak position of the surrounding rock.Therefore,it is meaningful to study the stress,deformation characteristics and stability of surrounding rock under soft rock surrounding rock tunnel construction.In this paper,the failure characteristics of the collapse of soft surrounding rock tunnel are analyzed firstly,and then the road tunnel of a V-class weak surrounding rock is taken as the engineering background,and the stress and deformation characteristics of the surrounding rock under the action of CRD construction of the soft surrounding rock tunnel are The stability of the surrounding rock has been studied in depth.The following are the specific research work and research results:(1)The classification methods of tunnel collapse and the main factors affecting the tunnel collapse are summarized.At the same time,the collapse characteristics of the soft surrounding rock tunnel are analyzed by the deformation and stress characteristics ofthe weak surrounding rock tunnel,and then the tunnel is judged from the perspective of the surrounding rock stress and deformation.Whether the surrounding rock is unstable.(2)A similar material model test was carried out with a V-class weak surrounding rock road tunnel as the engineering background.Firstly,the model test similarity ratio is determined by the similarity theorem and the actual situation.Then the ratiometric test is used to determine the model material and model size,and the stress sensor and FARO3 D laser scanner monitoring scheme are designed to monitor the stress and deformation of the tunnel surrounding rock.Finally,tunnel excavation is carried out in accordance with the excavation sequence of the CRD.(3)Through the monitoring of CRD tunnel excavation in model test,the progressive failure process of tunnel surrounding rock is first described,then the stress and deformation characteristics of tunnel surrounding rock are analyzed,and finally the ultimate displacement value,displacement rate,displacement acceleration and time are passed.The displacement curve judges whether the surrounding rock of the tunnel is unstable.(4)The MIDAS/GTS software was used to simulate the tunnel excavation process of the model test.The numerical simulation results of the arch settlement,the hole convergence and the surface settlement of the tunnel are compared with the results of the similar material model test.The force variation and deformation characteristics of the surrounding rock of the tunnel are obtained,and the tunnel collapse is analyzed by the change of the plastic zone of the tunnel surrounding rock.feature.