Experimental Study on the Mechanical Behavior of Composite Foundation of Submerged Shallow Buried Loess Tunnel

Collapse deformation is a difficult problem that has been faced during the construction, operation and maintenance of loess tunnels. Composite basement plays a key role in the construction of loess tunnels, effectively alleviating the collapse deformation problem of loess tunnels. In order to study the bearing capacity and collapsible deformation of the composite basement of tunnel in collapsible loess stratum, the stress and deformation characteristics of the composite basement under water immersion and non-water immersion conditions are studied through indoor large-scale model test method. The results show that the stress response depth of each measuring point of the composite basement is larger than that of the natural basement, which is basically within 60cm. However, the decreasing range of soil stress in the foundation is smaller than that without pile; Water immersion can increase the contact pressure between pile top and pile, but the changing trend of pile top pressure is relatively large; In addition, water immersion can reduce the stress increment in the reinforcement area and increase the stress increment in the underlying layer.