Centrifuge modelling of long-term load acting on a tunnel fixed in space in soft clay

A series of centrifugal model tests was conducted to examine the long-term loads acting on a tunnel fixed in space in soft clay, experiencing long-term deformation. Two possible hydraulic boundary conditions were adopted in the experiments: ‘tunnel drainage condition’ where the tunnel lining acts as a drainage boundary, and ‘bottom drainage condition’ in which one-dimensional consolidation of the clay takes place due to lowering of the ground water level. The test results are compared in view of the mechanism of ground deformation around the tunnel and the variation of earth pressures on tunnel lining.