Bersan, S, Koelewijn, AR & Simonini, P 2015, 'Application of distributed temperature sensors in piping-prone dikes', in PM Dight (ed.), FMGM 2015: Proceedings of the Ninth Symposium on Field Measurements in Geomechanics
, Australian Centre for Geomechanics, Perth, pp. 475-486, https://doi.org/10.36487/ACG_rep/1508_32_Bersan
In the past two decades, Distributed Temperature Sensing (DTS) systems have been installed in a number of dams with the aim of detecting internal erosion. The functioning principle is based on the fact that the temperature distribution inside an embankment dam changes when a leakage occurs. In addition to the benefits given by the use of optical fibres in lieu of electrical sensors, a major advantage of this technique lies in its high spatial resolution (up to two measurements per metre) achievable over long distances with a single sensor. DTS looks also promising for the monitoring of dikes prone to piping. With this term, we address the mechanism that occurs under hydraulic structures lying on a permeable and erodible foundation soil. The temperature variations measured so far by DTSs at the initial stage of piping are of little extent, thus the detection of piping when there is still time for intervention before the dike collapses is not straightforward. The effectiveness of a fibre-optic DTS system to detect piping has been tested in a largescale failure test run in the Netherlands in 2012 on a dike built on purpose for the experiment. This paper describes the set-up of the experiment and presents the temperature data obtained. A thorough analysis of the data gives insights on the process of heat transfer under a dike as well as on the development and evolution of thermal anomalies around leakages. It emerged that the onset of thermal anomalies around piping channels, and so their magnitude, depends on a number of site specific factors, among which the duration of the flood event. The minimum acceptable specifications of a DTS system for real-time piping detection are also discussed.
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