The Simulation Study On Immersion Process Of Long Immersed Tunnel Element

Because of its unique advantage, underwater tunnel has become a primary choicewhen people build engineering to cross the river. In various form of tunnel, theimmersed tunnel method with its advantages such as cost saving, quality guarantee,less tunnel construction site work, gets widely attention and application.The topic of this paper comes from HongKong, Zhuhai and Macau bridgeimmersed tunnel engineering. The whole tunnel’s length is nearly6000kilometers.And the tunnel element is180meters’ long, which is the world’s longest singletunnel section. The construction of ocean-crossing immersed tunnel in our country isunprecedented. In the complicated ocean environment conditions, the immersion ofthe long tunnel element is a key link and also the most dangerous link. To understandand study the motion of the tunnel will contribute to the tunnel’s movement stabilityand construction safety.At present in china,the study on immersed tunnel mainly based on tunnel acrossrivers. While the immersed tunnel crossing ocean is located in complex environment.Because of the wave,current,tide and wind in the sea,its immersing construction isdifferent from the tunnel across rivers. So except of the necessary modal test, theoryanalysis and numerical modal study also should be carried out. The paper focuses onthe immersion process of the tunnel element. The main work include:At first, based on the three dimensional potential flow theory, author analysis thetunnel element’s force,then build numerical model by using ANSYS software andconduct frequency domain and time domain analysis through AQWA software.In the frequency domain analysis, author simulate the tunnel element’s motion inthe regular wave, and calculate the element’s wave force, its added mass, andradiation dumping when the wave’s frequency change.In the time domain analysis, the study focuses on the immersing process. Authorput research on the element which is forced by both irregular wave and current, and try to observe when the immersing depth changes, or when the wave’s directionchanges, or when the wave’s length changes, how will the element’s motion and thecables’ tension chang in the meanwhile. With this author hope to provide basis andreference to the tunnel construction.