Diagnostic evaluation of quay wall using three-dimensional acoustic measurement systems

We used two types of acoustic measurement systems to assess the state of quay wall. Collapse and subsidence of quay wall at a harbor are often reported and a diagnosis method to prevent the accident has become a significant concern. The collapse is mainly occurred by air hole inside the quay wall. Therefore, the more robust and accurate diagnosis system is required and we try to apply the new diagnosis system which enables to assess the both inside and outside states of the quay wall from the underwater site. In the present study, two types of acoustic measurement systems using dual frequency identification sonar (DIDSON), and narrow-beam parametric sub-bottom profiler (SES2000) are applied to assess the both inside and outside states of quay wall. The field experiment was performed at the Iwanai port in Hokkaido, Japan (42° 59´ N, 140° 30´ E). The DIDSON was used generation of image mosaic and tree-dimensional image of the surface of quay wall. The SES2000 was created acoustic profile of inside the quay wall. The outside and inside acoustic images of the damaged quay wall were reconstructed from the collected data of DIDSON and SES2000. We detected corrosion hole. In addition, we detected corrosion holes and aged deterioration at other survey points using these two- and three-dimensional images. The state of the quay wall was quantified and compared with the results of direct measurement by diver. We should take more data in various field conditions and the continuous work with the proposed methods is needed for the practical use of them.