The Interaction Between Shield, Ground and Tunnel Support in TBM Tunnelling Through Squeezing Ground

When planning a TBM drive in squeezing ground, the tunnelling engineer faces a complex problem involving a number of conflicting factors. In this respect, numerical analyses represent a helpful decision aid as they provide a quantitative assessment of the effects of key parameters. The present paper investigates the interaction between the shield, ground and tunnel support by means of computational analysis. Emphasis is placed on the boundary condition, which is applied to model the interface between the ground and the shield or tunnel support. The paper also discusses two cases, which illustrate different methodical approaches applied to the assessment of a TBM drive in squeezing ground. The first case history-the Uluabat Tunnel (Turkey)-mainly involves the investigation of TBM design measures aimed at reducing the risk of shield jamming. The second case history-the Faido Section of the Gotthard Base Tunnel (Switzerland)-deals with different types of tunnel support installed behind a gripper TBM.