DBPapers
DOI: 10.5593/sgem2012/s07.v2006

DEFORMATION MONITORING WITH TERRESTRIAL LASER SCANNING: MEASUREMENT AND PROCESSING OPTIMIZATION THROUGH EXPERIENCE

T. NUTTENS, A. DE WULF, G. DERUYTER, C. STAL
Wednesday 1 August 2012 by Libadmin2012

References: 12th International Multidisciplinary Scientific GeoConference, www.sgem.org, SGEM2012 Conference Proceedings/ ISSN 1314-2704, June 17-23, 2012, Vol. 2, 707 - 714 pp

ABSTRACT

Terrestrial laser scanning offers the possibility to collect millions of very accurate 3D
points in a short time. As a result of the high measurement speed and the achievable
accuracy laser scanning has become a commonly used technique for recording e.g.
archaeological artifacts or cultural heritage sites. Furthermore, terrestrial laser scanning
is frequently deployed in civil engineering projects.
Based on the experience from two recent deformation monitoring projects in Belgium,
the applicability of terrestrial laser scanning for ovalization monitoring of newly built
tunnels is assessed. During these monitoring projects, different types of measuring
instruments (laser scanners and robotic total stations with scanning function) were
tested and compared. For all measuring instruments, an experimental standard deviation
was calculated, so an accuracy assessment could be made. In order to optimize the
measurements on site, further research has been performed on the optimal scanning
positions, scanning resolution and placement of reference markers (‘targets’) during the
measurements. Moreover, the workflow for processing the laser scan data and the
comparison of the subsequent measurements of a specific tunnel ring has been
developed and optimized during these monitoring projects. This workflow aims to
process the data as efficient and as accurate as possible, with user supervision in every
step of the workflow. These processing steps result in clearly interpretable results, such
as easily comprehensible drawings and tables, containing all necessary information on
the changes in ovalization of a specific tunnel section.
By controlling and optimizing each step in the project, a thorough risk assessment of the
tunnel structures is ensured. Also, the risks of performing the actual measurements on
site are minimized by optimizing the measuring equipment, the instrument settings and
the measuring process in order to reduce the required measuring time, without reducing
the quality of the data.

Keywords: Terrestrial laser scanning, tunnels, deformation measurements, monitoring,
risk assessment