Analysis and identification of the temperature field of dam leakage based on infrared thermal imaging

Leakage is the most common issue encountered in earth-rock dam projects, with characteristics of strong concealment in the initial stage and rapid development and significant threat in the later stage. For a rapid and accurate detection of leakage in earth-rock dams, this paper introduces an infrared thermal imaging technology by fully considering the correlation between dam leakage and temperature. The principle behind the application of this technology for the noncontact detection of water leakage in earth-rock dams was expounded. Based on the theory of flow-heat coupling and combined with a numerical simulation test on the leakage detection of earth-rock dams under the effects of varying water heads and water-air temperature differences, the feasibility of the infrared thermal image technology in detecting leakages in these dams was verified, and the infrared image characteristics of leakage outlets in the dam and their influencing rules were thoroughly analyzed. The results showed that the leakage in the earth-rock dam led to low-temperature anomalies in the leakage outlet area. With the increase in the water air temperature difference and water head, these low-temperature anomalies became increasingly evident. The temperature and water head of the leakage outlet showed a decreasing trend that could be characterized by a quadratic polynomial. The infrared images captured by the UAV could vividly and intuitively present the temperature anomalies caused by leakage, manifesting as a temperature stratification phenomenon with low values inside and high values outside. The temperature measurement accuracy of an infrared thermal imager is positively correlated with reflectivity in a linear manner, whereas it is negatively correlated with the detection distance. Additionally, with an increase in the angle between the focal plane of the infrared thermal imager and the normal direction of the soil dam surface, the temperature measurement accuracy decreases. The development of an unmanned aerial vehicle utilizing the proposed technology for leakage detection in earth-rock dams, along with the identification of abnormal temperature fields indicative of leakage on the dam surface, holds significant importance. This technology contributes to the rapid and accurate detection of leakage hazards, ensuring the safety of earth-rock dam engineering projects.