Model test of immersed tube tunnel foundation treated by sand-flow method

Highlight
• We proposed modeling principles and designed test model for sand-flow model test.
• We explored the expanding process of the sand deposit by full-scale test.
• Distribution of water pressure under the model board was gained.
• The water pressure in crater linear increased with the sand-deposit radius.
• Proposed bases for sand-flow construction control in immersed tunnel engineering.

In order to explore the immersed tunnel foundation treated by sand-flow method, modeling principles for the full-scale model test of sand flow were put forward. In addition, a sand-flow test model was built, which consisted of model system, equipment system and measurement system. The situation of sand-deposit expanding and the water pressure in the foundation trench were evaluated through the model test. The results show that a semi-closed space was formed between the model board and the expanding sand deposit, which made the water pressure in it rising with little range of volatility. The sand deposit gradually became non-circular truncated cone which shaped with its expanding radius, and the difference of the water pressure increased at each direction. The water pressure in crater had a linear increase with the sand-deposit radius, with a maximal value of 0.015 2 MPa. The volatility of the water pressure under the tunnel board and the water pressure value in the crater could be used as bases of construction control.