Report

Fibre-Optic Distributed Acoustic Sensing for Detection of Seepage and Internal Erosion

Optical fibres are installed in almost 100 dams in Sweden today. They are used for detection of seepage based on Distributed Temperature Sensing, DTS or movement, based on Distributed Temperature and Strain Sensing, DTSS.

Most of those installations can also be used for acoustic measurements such as Distributed Acoustic Sensing, DAS. The recent development of the technology, regarding both monitoring and analysis techniques, may give an additional method to study the seepage/internal erosion phenomena in dams and furthermore to provide information on the integrity.

The objective of this study is to make passive seismic measurements at a small dam to evaluate its sensitivity and its potential for subsurface dam monitoring. There are two passive seismic techniques that can be applied using DAS, seismic monitoring/imaging using recordings of the ambient noise field or monitoring of the sound of flowing water, making use of acoustic emissions. A technique known as ambient noise interferometry is used to analyse the noise recordings.

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About the report

Report number

2020:682

Author

Sam Johansson, Anna Stork, Ari David, Michael Mondanos, Carl Nygren