Model Test on Ground Surface Settlement and Face Failure of Shallow Tunnel in Dry Sandy Stratum

Surface deformation and face failure may occur during shield tunneling in the shallow buried dry sandy stratum. The model shield machine is used to carry out the shield tunneling model test in dry sandy stratum. The surface deformation laws and the active failure process of the excavation face are analyzed by monitoring the surface deformation during advancing and face failure stages. It is concluded that the surface deformation curve is "M" shaped and asymmetrical about the tunnel axis. The surface settlement during face failure goes through two stages, and the surface collapse pit is approximately elliptical, whose center is located on the left side of the tunnel axis when the cutter head rotates clockwise.