Experiment and Analysis of Filling Degrees in Foundation of Immersed Tube Tunnels Treated by the Sand Flow Method

According to the influence of the lifting for immersed tubes, the roughness for bottom plates of immersed tubes and different injection sequences on the final expansion radius and gap filling of sand-deposite in the process of foundation treatment for immersed tube tunnels by the sand flow method, a full-scale test model of the sand flow method was constructed, and the influences of the above conditions on the expansion equilibrium and quality for sand-deposite were discussed by measuring and calculating filling degrees of the top surface, volume and radius of sand-deposite. Combined with the analysis of the expansion laws of sand-deposite, it was shown that the upward lifting of the pipe section was unfavourable to the expansion of sand-deposite, lower the filling degree was, poorer the expansion equilibrium and quality of sand-deposite were; the smooth material was used at the bottom of the pipe sections, which was conducive to expansion of sand-deposite and had a high filling degree and could improve the expansion equilibrium and quality of sand-deposite; the appropriate boundary sealing caused by different sand injection sequences would benefitted the improvement on filling degree of sand-deposite, improve the expansion equilibrium and quality of sand-deposite, and had no adverse effect on the final expansion equilibrium and filling quality of sand-deposite in gaps.