We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
Rockslide deformation monitoring with fiber optic strain sensors.
- Authors
Moore, J. R.; Gischig, V.; Button, E.; Loew, S.
- Abstract
With micro-strain resolution and the capability to sample at rates of 100 Hz and higher, fiber optic (FO) strain sensors offer exciting new possibilities for in-situ landslide monitoring. Here we describe a new FO monitoring system based on long-gauge fiber Bragg grating sensors installed at the Randa Rockslide Laboratory in southern Switzerland. The new FO monitoring system can detect sub-micrometer scale deformations in both triggered-dynamic and continuous measurements. Two types of sensors have been installed: (1) fully embedded borehole sensors and (2) surface extensometers. Dynamic measurements are triggered by sensor deformation and recorded at 100 Hz, while continuous data are logged every 5 min. Deformation time series for all sensors show displacements consistent with previous monitoring. Accelerated shortening following installation of the borehole sensors is likely related to long-term shrinkage of the grout. A number of transient signals have been observed, which in some cases were large enough to trigger rapid sampling. The combination of short- and long-term observation offers new insight into the deformation process. Accelerated surface crack opening in spring is shown to have a diurnal trend, which we attribute to the effect of snowmelt seeping into the crack void space and freezing at night to generate pressure on the crack walls. Controlled-source tests investigated the sensor response to dynamic inputs, which compared an independent measure of ground motion against the strain measured across a surface crack. Low frequency signals were comparable but the FO record suffered from aliasing, where undersampling of higher frequency signals generated spectral peaks not related to ground motion.
- Subjects
SWITZERLAND; FIBER optics; DETECTORS; BRAGG gratings; SIGNALS &; signaling
- Publication
Natural Hazards & Earth System Sciences, 2010, Vol 10, Issue 2, p191
- ISSN
1561-8633
- Publication type
Article
- DOI
10.5194/nhess-10-191-2010