Crack imaging of underwater concrete components using interfacial waves and transducer array

Existing methods to detect cracks on underwater concrete components are mainly based on sonar scanning and visual inspection. However, these methods are fundamentally limited by low illustration, aquatic plants, and suspended sediments. Therefore, interfacial waves are used to image a 0.1-mm-wide crack on an underwater concrete slab for the first time. The wave scattering and mode conversion phenomena at a water-filled crack are investigated. The incidence of Scholte waves and their reflection in the form of Rayleigh waves dominate the wave field and are selected to detect the crack. An imaging algorithm is proposed based on the interfacial waves and a transducer array. The absolute errors of crack localization are less than 7 mm with a detectable range of 0.4 × 0.4 m of a single measurement. The proposed method can provide key techniques to evaluate the integrity of underwater concrete structures, such as water dams, bridge piers, and water pipelines.