Deformation analysis of a bored tunnel by means of terrestrial laser scanning

Abstract

A procedure is developed, implemented and tested to detect deformations in a bored tunnel. Deformations can occur after construction of the tunnel is finished, i.e. between two measurement epochs, but also deformations of the completed tunnel with respect to the design model are considered. For this procedure first the tunnel model is fitted to a point cloud consisting of several registered terrestrial laser scans using a linearized iterative least squares approach. This results in approximately optimal values for the tunnel model. Then deformations with respect to this tunnel model or between epochs are determined by means of a statistical testing procedure. Results performed together with the municipality of Rotterdam show that the studied tunnel is not so much ovalizing as a whole after construction, as was expected, but rather that single tunnel segments show different deviation patterns. 1.