Optimization Of Excavation Method For Large Section Shallow Buried Channel And Stress Characteristics Of Lining Structure

With the acceleration of China’s urbanization process,the problems of traffic congestion and traffic shortages are urgently needed.The application of underground passages is the most common method to solve the problem of dense pedestrian flow across urban main roads.Due to the existence of existing roads and pipelines,in order to ensure the safety of the tunnel excavation process,it is necessary to strictly control the surface settlement and deformation of the lining structure after excavation of the underground passage.Traditional excavation methods need to be optimized according to engineering conditions for efficient and stable construction.The most common method for engineering excavation method research is numerical simulation method.This method can compare and analyze the advantages and disadvantages of different excavation methods,and can analyze the deformation characteristics of lining structure to provide support for engineering construction.This paper takes the underground passage of Huazhong Normal University in Wuhan Xiongchu Street as the engineering background and studies it from the following aspects:(1)The definition conditions of shallow buried underground passages are introduced.At the same time,the law of formation deformation caused by underground passage excavation and the mechanical mechanism of lining structure stress are analyzed.The four most commonly used excavation methods for shallow buried channels are compared and analyzed.The difference in engineering application provides a theoretical basis for the establishment of the numerical model simulation channel excavation process.(2)According to the engineering conditions of the Huashi Passage,a twodimensional plane model is established to simulate the excavation process under different section segmentation forms.The advantages and disadvantages of various segmentation forms in the control of surface subsidence are compared and analyzed,and the conditions of actual construction are determined.The optimal solution for dividing the section into 6 guide holes for excavation.(3)The numerical model of underground tunnel excavation under the two excavation methods of CRD method and improved CRD method is established by using finite element software MIDAS-GTS,and the ground settlement law caused by different excavation methods is studied.The results show that the improved CRD method can control surface settlement more effectively.(4)The numerical model of composite lining structure based on load structure method is established,and the initial support and secondary lining stress are analyzed.The results show that the lining structure is inferior to the center of the arch,arch and shoulder.In order to ensure the key points that need to be paid attention to during the construction process,the safety of the lining structure is evaluated by the safety factor of the key points to provide support for the optimization of the monitoring point layout scheme.