Centrifugal model experimental study on natural foundation of immersed tube tunnel

Base stress distribution characteristics and the deformation characteristics of immersed tube tunnel in excavation and filling process of tunnel engineering occupies an important position. Taking one cross-sectional of the natural foundation in Hong Kong-Zhuhai-Macao immersed tube tunnel as research object, centrifugal model test of the whole construction process with different cushion layer thickness was carried out. When excavation rebound and backfill compression in the immersed tube tunnel, stress distribution and deformation characters of natural foundation, the strain characteristics of immersed tube structure and the influence of cushion layer thickness had been revealed. That provides the design basis for the construction of immersed tube tunnel and scheme of ground treatment. The results show that, excavation unloading makes basement produce arch distribution rebound. Basal stress distribution is the shape of a saddle after backfill, and only the stress in the middle of base is increasing with time and silting. The strain distribution of immersed tube plate is the shape of a saddle and strain has little change after construction. Cushion layer thickness thin lead to smoothing effect on basal stress distribution is poor, and recompression quantity and foundation settlement after construction is large.