ABSTRACT
Dr. Standing opened the discussion by asking Dr. Caporaletti for some elaboration on the focal point of the displacement vectors. In the model experiment the displacement vectors seem to originate from below the tunnel axis. This disagrees with Standing’s experience that the focus of the displacement vectors in greenfield situations is found about 1D above the tunnel crown. The latter was found in a profile with sand and gravel layers above London clay, which is similar to the model geometry. Caporaletti answered that in her experiments the focus of the displacement vectors is located above the tunnel axis. Therefore the model experiments are in agreement with the prototype tests (in situ). The correct approach of this focus point is very important for damage assessment.
