Abstract: The deep-medium passage immersed tube tunnel has the characteristics of super large span, super wide, and large back silt, etc. It adopts a steel-shell wrapped plain concrete structure to separate the steel shell production from the concrete pouring. In order to verify the deep-medium passage steel-shell self-compacting concrete pipe section for the feasibility of construction process, large-section model tests were carried out to study the properties of self-compacting concrete, the precast pouring process of steel-shell floating state and the quality of the model structure to ensure the reliability of pipe joints in the construction process. The results show that, through the preparation of self-compacting concrete, the performance of the concrete mixture meets the basic performance requirements of fluidity, filling and segregation resistance. Through monitoring the temperature and strain of the model concrete and testing the compressive strength in the large-section model floating pouring test, the temperature of the steel-shell self-compacting concrete has been well controlled, and the self-compacting concrete prepared has a good volume stability. The 28 d compressive strength of concrete is above 50 MPa, and its compactness and homogeneity are good, and it meets the requirements of the compounding index. The construction process of floating self-compacting concrete with steel-shell immersed pipe is feasible.

Key words: immersed tube tunnel, large-section, self-compacting concrete, floating pouring, model test