Study Of Mechanical Characters Of Subsea Water-intaken Shield Tunnel With Double Lining

Use of shield tunnel technology in our country has more than50years of history, but it will shield method be used for the water conveyance tunnel is a rare at home and abroad. Lining consist of segments and formworking concrete is increasingly applied in the large-scale water conveyance tunnel and sewage pipe recently.However, there have been deviation and dispute on the understanding of mechanical behavior and the role of the secondary lining in shield tunnel and its calculation methods for a long time. So research on the mechanical properties of double-layer lining of circular water pressure tunnel has become an important issue.This thesis conducts research on the basis of taishan nuclear power station water-intaken tunnel, Theoretical analysis, field monitoring, numerical analysis and other research means are mainly adopted to analyze unravel the transverse mechanical characteristics of the double-layer lining in the large-scale subsea shield tunnel, to explore the interaction mechanism between segments and secondary lining, and to study the effect of different parameters on the mechanical characters of double-layer lining, meanwhile, on the basis of predecessors’research, it has carried out detailed research work, the main work is as follows:(1) Investigating the characteristics of calculating model of single layered segment lining for shield tunnel and the interaction between double-deck lining of shield tunnel, With the existing calculation theory and research results, it establishes beam-spring calculation model under load-structure mode.(2) Field-test research relied on double-layer lining of taishan nuclear power station water-intaken tunnel was conducted,ascertaining the impact of synchronized grouting and jack thrust on the segmental lining structure during shield tunneling. The long-terra variations of water and soil pressure are revealed, Study on the computation and discount coefficient of the external loading for shield tunnel in soft stratum, analyze the fact of the bearing mode of double-layer lining with long-term monitoring data of the secondary lining.(3) Based on the characteristics of the existing calculation model of shield segment lining,this paper establishes beam-spring calculation model by using the large universal finite element program ANSYS. Using the model to analyze the segment structure inner force in different embedding depth along the tunnel and comparing the calculation results and field measurement record, this paper verifies the accurate and feasibility of the model and result.(4) The research puts emphasis on influence of the segment joint and the axial compression stiffness of contact surface on internal forces of double-layer lining structure and mechanical analysis of whole construction process, Besides,we preliminary discuss the optimization structure design of the double-layer lining.(5) Combined with the road and railway constuction experience of domestic and foreign double-layer lining structures and the technology for secondary lining construction practice of taishan nuclear power station water-intaken tunnel project, this paper concludes the construction technology that suitable for China’s lining consist of segments and formworking concrete and presents the corresponding consturction requirements.