Monitoring water seepage velocity in dikes using distributed optical fiber temperature sensors

Seepage in dike engineering, especially its soil-concrete joint, is one of influencing factors of dike safety. Most of disastrous accidents of dike engineering are induced directly or indirectly by seepage. The reliable observation and reasonable identification of seepage behavior play an important role in ensuring the service safety of dike engineering. In this paper, a distributed optical fiber temperature sensor system (DTS)-based approach is presented to monitor the seepage velocity in soil-concrete joint between dike structure and other constructions across it such as culvert and sluice. The theoretical investigation and laboratory test are carried out. Firstly, the DTS-based monitoring principle of seepage velocity is introduced. The theoretical model identifying seepage velocity is established. Secondly, a DTS-based test platform of soil-concrete joint, which can simulate the structural feature and service environment of dike engineering, is designed and constructed. It consists of DTS, heating system, water-supply system, data processing system and dike model. Thirdly, the monitoring experiments on seepage velocity under the conditions of different mediums and optical fibers are implemented using the test platform. The correlations between seepage velocity and heating power, temperature change of optical fiber are analyzed. The practical model monitoring seepage velocity of soil-concrete joint in dike engineering is built. Lastly, considering the seepage features of dike engineering, the embedment mode and procedure of optical fiber are proposed to promote the application of DTS-based approach to real-time observation of seepage velocity in actual dike engineering.