Application of borehole radar for dam leakage detection

A borehole radar investigation was performed at Sanzuodian reservoir, Chifeng, China to assess the existence of the deep rock-filled dam leakage. The key methodology used includes both single-hole reflection profile and cross-hole radar tomography, which allowed identification of the hydraulic connections between the upstream side and the downstream side in deep foundation. The leakage path is characterized by direct wave loss due to high attenuation in single-hole reflection profile, and horizontal banded low-velocity zone in cross-hole velocity tomography. Meanwhile, the core wall thickness change point, connection point of asphalt/concrete wall, and the water saturated interface can be identified by single-hole reflection clearly. The interpreted leakage path is proven by water flow measurement. Borehole radar is a high-resolution tool fitted for deep detection.