Thermal Monitoring of Embankment Dams by Fiber Optics

Internal erosion is the main cause of failure of earthen hydraulic structures. Moreover, it is often difficult for the operator to detect internal erosion at an early stage. For the last twenty years, leakage detection by thermometry has been developed mainly in Europe. The principle is based on the fact that a leakage through an embankment dam changes its temperature field. In this regard, fiber optics buried in the structures can be used as temperature sensors. Their principal advantage is distributed temperature measurements, at every meter along their length, and over long distances. Indeed, once deployed, optical fiber proves to be an effective mean of probing several kilometers, making it extremely useful for monitoring dikes. Various methods have been developed for analysis of temperature data acquired by these powerful sensors. Thesephysico-statistical and signal processing methods allow to propose a system for "early warning" or for long-term monitoring. Based on the results of several tests at controlled and industrial sites, this presentation will demonstrate the improvement of this surveillance methodology for the safety procedures of embankment dams