The use of fibre optic distributed sensing technology to detect changes in sediment overburden

Fibre optic cables can be used as sensors to monitor changes in temperature and strain through the analysis of backscattered light. This can be linked to changes in the ambient conditions surrounding the cable. Active distributed temperature sensing relies on an external heat source relative to the fibre optic cable to measure the properties of, and changes in, the surrounding medium. An experiment was conducted using fibre optic sensing technology to monitor changes in sediment overburden. Fibre optic cables were buried in a channel containing saturated sand and water with an external heat source. The depth of overburden sediment above the cables was reduced, while the associated temperature response along the cable was monitored. This paper explains the characteristics of heat transfer from an active heat source to the surrounding soil medium providing a means to translate from the temperature measurement to the associated overburden thickness. The techniques used here are intended to be applicable to measurements of seabed scour above buried power cables.