Assessment of design parameters for TBM tunnelling in weak and water-bearing ground and through fault zones

Abstract: The correct evaluation of the most pertinent geomechanical parameters assumes increasing importance due to the current trend of today’s planned infrastructure projects for which owners and planners quite frequently plan tunnels with diameters larger than 13 meters to be excavated by universal tunnel boring machine. The risks associated for large to very large tunnel profiles are emphasized particularly in rock masses exhibiting squeezing or large deformation behaviour and where the hydrogeological conditions, particularly the hydraulic head and its possible variations, may play a significant role for the stability of the tunnel face and walls.