Simulation Study on Image Characteristics of Typical GPR Targets in Water Conservancy Projects

With the development of the global economy, the deep leakage of reservoirs is still a serious threat to the foundation construction of key water conservancy projects such as dam foundations and bridges. Ground penetrating radar (GPR) is an effective underground imaging and detection technology. In this paper, the Groundvue series of ground penetrating radars is introduced in Britain using the 948 project fund of the Ministry of Water Resources. It is a radar with the lowest frequency in the world at present, improving detection depths and helping to ensure the reliability of a reservoir dam’s foundation. Through a large number of field tests, simulation experiments, FDTD numerical simulations, and practical engineering applications, this paper summarizes the reservoir leakage analysis method based on the Groundvue radar. The successful application at the Nanmenxia Reservoir shows that this method can effectively detect the location and path of reservoir leakage and provide technical support for the design and construction of a reservoir reinforcement project.

Exploring the Occurrence of Clogging in Highly Permeable Coarse Soils of Dam Foundations

Leakage through the permeable coarse soils of dam foundations in Tibet, China, lessened over time without any additional antiseepage measures. In fact, clogging generated during the infiltration process is recognized as the major factor in reducing leakage. A laboratory study was conducted to understand clogging in highly permeable coarse soil of a dam foundation with the primary aim of determining the clogging patterns and optimum clogging particle size (PS). Seven replicate experiments were constructed using soil media with PS ranges of 32–64 mm, 16–32 mm, 8–16 mm, 4–8 mm, 2–4 mm, 1-2 mm, and 0.5–1 mm to observe clogging after feeding the soil media with sediments of different PSs. The experimental results showed that four clogging patterns were formed in different PSs of the coarse foundation soil. The ratio of the effective aperture of the soil Dea and the equivalent clogging particle size dede/Dea had a dominant effect on the four clogging patterns (surface clogging, de/Dea>1; surface-internal clogging, 0.5<de/Dea≤1; internal partial pore blockage, 0.25<de/Dea≤0.5; and unclogging, de/Dea≤0.25). The assessment criterion of the optimum clogging pattern was determined by 0.5<de/Dea≤1, and from that, the optimum clogging PS do was calculated.