Abstract The steel plate is usually used as the liner of some concrete structures in hydropower projects. For some reason, there are usually some cavity defects in these structures. It is hence necessary to employ some non-destructive detection technology to detect these structures so as to determine the existence or nonexistence of the defects and confirm their locations and sizes. These measures provde scientific basis for the subsequent processing. The authors adopted this technology to detect cavity defects in concrete under the spiral case steel liner in a pressure pipe of a Dadu River hydropower station project. The detection results have revealed some cavity defects in the concrete and found their areas, sizes and depth ranges. The results show that the non-destructive detection technology applied in detecting cavity defects of concrete under the spiral case steel liner has an ideal effect.
