Study of the influencing factors of compressive characteristics for the foundation layer of undersea immersed tube tunnels
Gang Wei 1, Jian-jian Xing 2, Hui-jie Qiu 2, Ze-fei Yang 1, Dong-di Wang 1
COMPUTER MODELLING & NEW TECHNOLOGIES 2014 18(12A) 473-484
1Department of Civil Engineering, Zhejiang University City College, Hangzhou 310015, China；
2 Institute of Geotechnical Engineering, Zhejiang University, Hangzhou 310058, China
Shenjiamen undersea immersed tube tunnel in Zhoushan, Zhejiang was taken as prototype to establish a 1:10 scale model with 30m in vertical length. The formation process of sand grouted foundation layer in seawater environment was simulated in the experiment considering the interaction of gravels during the formation of foundation layer. Different construction factors were examined by incorporating different design boundary condition, back-silting condition and sand grout density. Results showed that in the boundary condition of one end fixed and the other free, the settlement at the free end of the tube increased significantly (approx. 3 times) and the timeframe for settlement to stable increased; back-silting increased the overall condensability of the foundation layer and leaded to non-uniform compression; the reduction of sand-water ratio of the grout reduce the compressive modulus of the foundation layer. Further settlement occurred when the load exceeded the limit which is detrimental towards the global stability of the foundation layer. Comparing the effects on the settlement of foundation layer or compressive modulus, the factor of one end fixed and one end free was most significant, followed by back-silting and reduced sand-water ratio.