Research On Prefabrication New Technology Of Immersed Tunnel Reinforced Concrete Element And Key Technical

With the rapid development of the society and economy,the Bay Area development concept has been gradually applied to different areas.This theory pays more attention to the integration of land and sea,and retains the original advantage of sea while realizing land connectivity.In this case,the advantages of underwater tunnels have become prominent.It can not only solve the problem of crossing waters,but also maintain the original navigable advantages,and the traffic is not affected by the adverse weather.Among them,the immersed tunnel method has become the main form of underwater tunnel construction because of its advantages.Therefore,this paper systematically analyzes and studies the existing prefabrication methods of immersed tunnel elements,and puts forward a element flat ground flow line prefabrication and dynamic water entry new technology by using the innovative technology of process combination.Based on the actual project,the design of the wheel-track trolley moving system is completed,and the element moving process is studied.The main research contents are summarized as follows:(1)The general process flow of fixed dry dock method,mobile dry dock method and factory method is studied from the construction conditions,process characteristics and construction difficulties of each technology are analyzed.The relevant data of reinforced concrete immersed tunnels built in the world are analyzed,and the relationship between the selection of precast methods of reinforced concrete elements and the construction scale is analyzed,puting forward the selection table of precast methods for reinforced concrete elements.(2)Through the in-depth investigations into the three element prefabrication methods,this paper analyzes the difference in them,and concludes that the difference is threefold.Six combinations are constructed depending on the process classification.Based on the comprehensive comparison and selection from multiple perspectives including the novelty,cost-efficiency,and feasibility,the mature and high-cost processes are ruled out,whereas the technology of element flat ground flow line prefabrication and dynamic water entry is recommended.(3)This paper standardizes the construction process of the element flat ground flowline prefabricated dynamic water entry technology: The steel reinforcement cage of the element is tied to the concrete pouring,and then moved to the outfitting area and transported to the semisubmersible barge using the element moving equipment,and finally transported by the semisubmersible barge to the submersible pit for barge removal.(4)With the support of the engineering cases,this paper applies the innovative technology of element flat ground flowline prefabricated dynamic water entry.The four key techniques of element prefabrication are introduced from the aspects of steel reinforcement cage movement,formwork construction,concrete pouring,and element movement.Regarding the element water entry process,its feasibility and the mechanical problems to be solved are explored,in accordance with the element discharging,element transportation,and element discharging process.(5)Based on existing engineering cases and new process requirements,the wheel-rail trolley movement system which can move 10,000-ton components by overcoming the rolling friction is constructed.Through the comparative and selective analyses,the wheel diameter and driving mode are determined,and the frame structure is analyzed numerically.The application of the system in Shenzhong Link is introduced,and the selection principle of hydraulic jack stroke is determined.The process flow for the movement of reinforced concrete elements from the pouring area via the outfitting area to the semi-submersible barge section is developed.