Study On Structural Optimum Design And Construction Of The Double-arch Tunnel Under The Action Of Bias

Double-arch tunnel has many advantages such as small floor area, smooth wiring,terrain restrictions and space higher utilization, which makes it more and more adoptedin some certain conditions for lines inconvenience separation, especially suitable for theshort tunnel and sometimes also applied to the long tunnel segment hole. However, dueto the characteristics of the double-arch tunnel structure itself, its unit project cost issignificantly improved, the structure stress also become very complex, and also oftensubject to unsymmetrical pressure by the geological terrain. At present, China has builtup a considerable number of double-arch tunnels, but there are also a lot of problems.For the double-arch tunnel bearing unsymmetrical pressure, on the one hand, theconstruction methods of different construction unit vary. Some construction methods isrelatively backward and a certain degree of irrationality, the construction quality is inuneven level; On the other hand, in order to improve its force environment and reducethe project cost, the double-arch tunnel structural design should be optimized sustained.Therefore, it becomes very important for the system summary, the analysis ofconstruction methods of the double-arch tunnel under the unsymmetrical pressure, andthe study of its structural design optimization.This paper takes the double-arch tunnel in Xiamen to Chengdu ExpresswayChuanqian sector Naxi segment on West Lake Hills as the engineering background tostudy and summarize construction methods and structural optimization design of thedouble-arch tunnel under the unsymmetrical pressure. The main content is list asfollows:①By systemic analyzing and summarizing construction methods of thedouble-arch tunnel under the unsymmetrical pressure, suitable and specific constructionmethods are contained respectively to the tunnel opening, the tunnel itself, and themiddle wall of the tunnel suffering the unsymmetrical pressure,.②By studying the section of the tunnel, the objective function optimizationmethod of the area of the excavation section is determined, and then combiningengineering examples the feasibility and effectiveness are discussing.③Asymmetric design of the initial support structure is done based on the theasymmetry of unsymmetrical load distribution. Through the finite element analysis toresearch feasibility of the double-arch tunnel initial support structure asymmetricaldesign under the unsymmetrical load and to identify the optimized design parameters of the initial supported structure.④Secondary lining structure is studied to determine optimization method whichutilizes the cost of per meter of the secondary lining structure as the objective function,and then the engineering examples are combined to discuss to get the second liningthickness optimal solution.