The Study On Joints And Structure Analysis Of Ventilating Shaft Of Cross-ocean Tunnel

Because of ventilating requirement of cross-ocean tunnel, especially long distance cross-ocean tunnel, ventilating shaft should be set in the sea. The existing ventilating shafts are all built on the artificial island, which not only consumes much capital but also is irrational in technology. As a result, ventilating shaft which stands by gravity is adopted in this paper. This kind of ventilating shaft is economic and rational in technology, but it still confronts some difficulties, such as: structure form, how to join with immersed tunnel and how to construct it in the sea. These difficulties are very important.Summarizing the existing experiences, this paper discusses the key technique difficulties of ventilating shaft building for cross-ocean tunnel and designs the structure form of shaft. The offshore construction problem of ventilating shaft to stand by itself is mainly introduced in this paper and shaft is suggested to sectional pre-cast. When shaft sink at sea, we suggest set special auxiliary equipment.Ventilating shaft standing in the sea is effected by much load, and exist much mechanics problems. This paper reduces loads and mainly considers wave load, static water load, hydrodynamic load and wind load and analyses the stability issue of shaft at sea by structural mechanics method.This paper also elaborates the theory of finite element of shaft-base structure and set up space finite element model of shaft-base structure based on the theory. Using the finite element analysis software MIDAS/GTS, stress and deformation of shaft-base model are solved. Base on the result, this paper analyses the reaction of the subgrade and comes to the conclusion that the shaft can stable by itself in the sea.