DBPapers
DOI: 10.5593/SGEM2015/B12/S2.019

BRILLOUIN OPTICAL TIME DOMAIN ANALYSIS IN GEOTECHNICAL MONITORING – TOPOGRAPHY OF THE SENSING CABLE

K. Capova, J. Zalesky, M. Zalesky, L. Sasek
Friday 7 August 2015 by Libadmin2015

References: 15th International Multidisciplinary Scientific GeoConference SGEM 2015, www.sgem.org, SGEM2015 Conference Proceedings, ISBN 978-619-7105-32-2 / ISSN 1314-2704, June 18-24, 2015, Book1 Vol. 2, 141-148 pp

ABSTRACT
In the past few years the authors of the paper were involved in the research project focused on the application of Brillouin Optical Time Domain Analysis (BOTDA) for distributed deformation measurement in geotechnics. The basic principles of the BOTDA method as well as the process of its laboratory testing, on site applications (together with geotechnical deformation measurements performed by high precision tools in order to compare the results) and development of necessary instruments of own construction have been already published in various literatures. One of the most important phases in the detection of deformation by the BOTDA is the description of the sensing cable topography.
The paper presents development of reliable process for association of BOTDA analyzer outcomes (providing two-dimensional relationship of the coordinate in the axis of installed sensing cable – “chainage” and detected strain or temperature change) and the optical measuring track in the geotechnical structure or in the host environment of the structure. The topography of the sensing cable allows obtaining possible critical spots of the structure and modeling of its behavior; the paper shows different possible ways of gaining of the sensing cable topography. This process is relevant for various geotechnical structures and environments such as retaining structures, potentially unstable slopes or tunnels and several examples of its realization are listed and described in the paper.

Keywords: BOTDA, geotechnical monitoring, fiber optics, sensing cable topography, chainage