ABSTRACT

The loading of the tunnel support in deep tunnels is one crucial factor in tunnel design. For a realistic assumption of the tunnel loading the deformation response for deep tunnels due to unloading is of importance. One possible measure of this deformation is the radial displacement of the tunnel, both, the pre-deformations ahead of the face and the convergences in the excavated area. This measure is often predicted by theoretical longitudinal displacement profile approaches based on several simplifying assumptions and, therefore, should be treated with caution, especially in case of deep tunnels in anisotropic and inhomogeneous rock the accuracy has not been investigated so far. In this study, the measurements of longitudinal displacement profiles for two lithologies at the BBT are presented. The entire radial displacement distributions (ahead of the tunnel face to the decayed displacements in the excavated area) have been measured by 40 m long horizontal chain inclinometers installed just above the tunnel crown prior to tunnel excavation. The plausibility of the measurements of the longitudinal displacement profiles is investigated in this contribution and contributes to a better understanding of deep tunnel induced deformation.