Study On The Durability Of Long-span Highway Tunnel Structure

With the practical project background of the Longtou Shan tunnel, it surnames the tunnel durability study method. By on-site and indoor experiments, it gets the optimized mix proportion ratio and forcasts the tunnel's life expectation. It makes the primary studies in improving the tunnel structure system's durability.For the durability analysis of Longtou Shan long-span tunnel, it has done greatly investigation and search, generally acquired the situation and advance in the structure durability; summarized the factors and its action principle which influenced the durability of structure. At last, the thesis applies the generally durability analysis method to the practical situation of Longtou Shan tunnel study. So we study the on-site geological environment, then do many concretee experiences according to the generally structure durability analysis method, get the optimized mix ratio for Longtou Shan lining structure, and predict the durability life expectation of the tunnel and compare the reliability in the similar situation, make some technological method to improve the tunnel durability.Longtou Shan tunnel is the largest bidirectional separated four-lane-road tunnel at present, its biggest excavation width is about 21m and excavation area is about 230m2, so it is necessary to study the long-span tunnel' durability. Based on the practical project, the main contexts studied are as followed:(1) It has introduced the general project situation of Longtou Shan tunnel. Through studying the long-span tunnels home and aboard, it summarizes the direction of durability research and main achievement in this field, it lastly puts forward the research principal of the tunnel durability.(2) It has stated in detail the factors and its action principle which influenced the tunnel lining structure's durability; it also explants the factors that influenced the shotcrete concretee's durability.(3) It has classifies the environment where the tunnel is. According to the generally structure durability research method, we have done a lot of concretee optimized mix ratio experiences and got the optimized ratio for Longtou Shan tunnel.(4) It mainly focuses on the life-expectation prediction of tunnel lining structure. According to the different prediction theory, it gives calculates the Longtou Shan tunnel lining durability life and explains the theories calculation resusts.(5) Based on the above study, according to the theory of reliability, the chapter compares reliability between the four-lane tunnel and two-lane tunnel to analysis the lining structure durability.(6) Waterproof and drainage system is one of important component part of tunnel; its durability deeply influences the tunnel's durability. In chapter 2 we have done many concretee experiences to study its anti-permeation itself, so this chapter we mainly study the construct technology and method which improves the system's mellifluence, and the drainage system can be clear and maintenance in time.It summarizes the above study and gives some comprehensive method and technology to improve the durability of tunnel.