ABSTRACT
At present, there is no ripe experience of settlement characteristics and calculation of soft foundation in offshore immersed tube tunnel. In this paper, rebound and recompression modulus of the natural foundation of immersed tube tunnel are studied by laboratory consolidation and rebound test. The law of soil rebound and recompression deformation changing with loading is revealed.
With the rapid development of port engineering and construction technology, the immersed tube tunnel will become the main way of cross-river and cross-sea project. To ensure the construction quality and operation safety of immersed tube tunnel, the requirements of installation precision and settlement control are very strict. Normally, the tunnel is placed in the excavated foundation trench, then, the trench is backfilled and the tunnel is locked. The foundation soil experiences the process of unloading and reloading. Therefore, the accurate calculation and characteristic analysis of rebound and recompression settlement of tunnel foundation are very important to ensure the safety of immersed tube tunnel.
In recent years, many scholars have carried out research on the resilience of foundation excavation. Duncun (1970) carried out the finite element calculation of foundation heave by using the curve model. S.K.Bose.N.N.Som (1998) used two-dimensional finite element method to simulate excavation process by steps of foundation and the change of support mode. Pan Linyou and Hu Zhongxiong (2002) put forward the concept about the range of rebound area and strong rebound area. Li Jianmin and Teng Yanjing (2010) proposed the concepts of reloading ratio and recompression ratio through the rebound and recompression test and model test of a large number of soil. And they also obtained the basic law of soil recompression deformation. Xv Gancheng and Li Yongsheng (1995) calculated the rebound deformation caused by excavation with different formulas.
Although the above scholars have carried out the systematic study on the soil rebound and recompression problem, however, there are few studies on the rebound and recompression of immersed tube tunnel foundation soil under special working conditions. Because of the regional difference of foundation soil, this paper is based on the immersed tube tunnel foundation of the Hong Kong-Zhuhai-Macao bridge. And the study on deformation characteristics and law of soil rebound and recompression are carried out.
