Analysis Of Surrounding Rock Deformation Characteristics Of Shallow Buried Tunnel In Harbin Metro

With the rapid development of China's economy,the level of urbanization continues to increase,and a large number of people are constantly flocking to cities.The development of the city is facing a severe situation,mainly in the areas of super-saturated urban population and crowded building space.The effective use of underground space can not only alleviate urban traffic problems,but also bring huge economic benefits.At the same time,the construction of urban tunnels has become part of the process of accelerating urban modernization.At present,the construction methods for constructing urban tunnels at home and abroad include shield construction method,shallow buried excavation method,and open cut method.Although the underground excavation method has less disturbance to the overlying soil layer,it will inevitably cause disturbance to the surrounding soil,which is the main reason for the deformation of the stratum.If the deformation exceeds a certain limit,it will affect the safety of the surrounding environment and adjacent buildings.Therefore,the prediction and control of ground deformation caused by tunnel construction has received increasing attention.Based on the shallow buried tunnel of Nanzhi Road Station of Harbin Metro Line 2,this paper uses theoretical analysis,field monitoring and numerical simulation to study the deformation characteristics and stability of tunnel surrounding rock.1.This paper briefly summarizes the characteristics and deformation mechanism of surface deformation of shallow buried tunnels,and reviews the changes of stratum stress state,ground loss theory and soil consolidation settlement during subway construction,and summarizes the deformation of surrounding rock.The factors affecting,and the main methods to control the deformation of surrounding rock are proposed.2.The purpose and significance of tunnel monitoring are briefly explained.Through the sorting of on-site monitoring data,the surface settlement,dome settlement and hole convergence caused by deformation of surrounding rock were analyzed.The deformation of the dome and the convergence of the arch waist are compared when the temperature is below 0?.When the temperature is lowered,the deformation of the surrounding rock at the arch is more obvious,and the deformation of the surrounding rock near the arch waist is smaller and tends to be stable.The excavation of the steps on the tunnel has great influence on the surrounding rock near the vault and the arch waist.Corresponding measures should be taken during the construction to ensure the stability of the excavation surface.3.The FLAC3D software is used to carry out three-dimensional numerical simulation analysis of the tunnel construction process,and the deformation of surrounding rock under different working conditions is compared and analyzed.The full-section excavation method is more disturbing to the surrounding rock around the tunnel,compared with the full-section excavation.In terms of method,the step method can effectively reduce the area of the excavation face and control the deformation of the surrounding rock.However,in the process of tunnel construction,the step method will disturb the surrounding rock of the tunnel many times.Stress concentration will occur at the arch waist and the bottom of the arch.The surrounding rock on both sides of the arch waist is prone to plastic deformation and should be carried out in dangerous areas.Focus on monitoring and timely support.