Ground movement and tunnel stability when tunneling in sandy ground

Tunneling may cause ground movements and damage to adjacent buildings and overlying facilities. In this study, the failure mechanism and ground movement behavior around tunnels embedded in sandy soil below the water table were investigated in a series of model tunnel tests in a centrifuge. The magnitudes and extents of the surface settlement troughs for the cases of various ground loss for tunnels buried at various depths are provided. A new failure mechanism is proposed and validated by comparison with the test results. The proposed mechanism enables accurate prediction of two of the key quantities in the design of linings for tunnels embedded in sandy soils, namely the minimum supporting pressure needed to retain tunnel stability and the vertical soil pressure acting on the tunnel crown.