Investigation on the deformation of ground due to shield tunneling in sensitive soft clay

In a construction site of shield tunneling, the settlement of the ground surface was successfully kept to be much smaller than the predicted one by empirically adjusting the construction conditions such as the cutter face pressure and the back-filling one. The relationship between the ground settlement and the construction conditions was studied through the field measurement and visco-elasto-plastic FEM analysis in order to understand the mechanism of the settlement and to find a method for reducing the settlement. In the discussion, the ground displacement was divided into the pre-displacement induced in the ground before the machine tail passed the side track and the subsequent displacement induced in a long-term after passage of the machine tail, and then the relationship among both displacements and the construction conditions was investigated. The possibility has been confirmed that the settlement of the ground surface can be decreased by controlling the pre-displacement through the adequate control of the cutter face pressure and the back-filling one.