OVALISATION MEASUREMENTS OF NEWLY BUILT CONCRETE TUNNELS BY MEANS OF TERRESTRIAL LASER SCANNING

This paper discusses the practical implementation of terrestrial laser scanning for ovalisation measurements of newly built concrete railway tunnels. Also an accuracy assessment is performed and then an overview of the measured deviations is given. This research is based on the ovalisation monitoring of concrete railway tunnels for the first projects of this kind in Belgium. These tunnels are measured with laser scanning during the first three months after construction. For all measurements, the concrete surface of the tunnel rings is scanned with a lateral resolution of 5 mm or higher with a phase-based Leica HDS6100 laser scanner. Based on the recorded point clouds of the tunnel rings, the deviations from ovalisation and the changes in ovalisation during the first three months filler construction are determined. During this research, a workflow has been developed to determine the deviations from ovalisation and the changes during the first three months after placement. The differences that are observed between the control measurements at the different points in time show a stabilization of the construction after one or two weeks after construction.