Seepage Assessment in Embankment Dams Using Active Fiber Optic Sensing Technology

Identifying and evaluating zones of seepage flow in embankment dams is a challenging issue for dam performance evaluation because there are few methods to directly measure seepage rates within a dam. Seepage  is a critical condition to understand for overall dam safety since seepage is the trigger for many failure modes in  embankment dams. Active Fiber Optic Distributed Temperature Sensing (A-DTS) is an emerging technological  application by which heat transfer around a fiber optic cable can be measured and correlated to material properties  or conditions. The A-DTS system consists of (1) an interrogator using laser pulses to measure temperature  continuously along the length of a fiber optic cable and (2) a heating cable to provide thermal power along the cable.  The heat transfer measured by the A-DTS in subaqueous conditions can then be directly related to the flow rate of  water over the cable. When applied within fully-screened piezometers through an embankment dam, including its  foundation or abutments, the principles of the operation allow for profiling of the seepage flow regime.