Leakage channel outlet detection and diameter estimation for earth-rock dam using ROTDR.

• ROTDR can be used to quantify the leakage channel outlet diameter in earth-rock dam. • A method for estimating the outlet diameter of leakage channel was proposed. • A practical deployment method of sensing fiber for leakage detection was designed. • The effectiveness of the proposed method was validated through outdoor model test. In the early stage of leakage in earth-rock dam, detection and quantification of the leakage channel outlet can provide an important reference for leakage hazard assessment and emergency response. In this paper, Raman Optical Time Domain Reflectometry (ROTDR) is used to detect the leakage point and a leakage channel outlet diameter estimation method is proposed. Firstly, the variation law between the sensing fiber of different length and ROTDR measurement results under the condition of different temperature difference is explored. Then, a model is constructed to simulate the leakage of earth-rock dam. The sensing fiber is deployed on the shallow layer of downstream slope and cushion of earth-rock dam to detect leakage. Finally, according to the measurement results, the leakage point is located and the diameter of leakage channel outlet is estimated. The estimated value is very close to the measured value. This study provides a useful reference for promoting the quantitative research of ROTDR in leakage detection. [ABSTRACT FROM AUTHOR]