Assessment and Repair for North Breakwater Dome in Wakkanai Port

Wakkanai Port, located in the northernmost part of Japan, has a breakwater called “North Breakwater Dome”, which is reminiscent of ancient Greek architecture. The Dome has played an important role not only as a seawall, but also as a central tourist facility in the area. Currently, the deterioration of the dome is becoming apparent. Accordingly, it was decided to conduct a comprehensive rehabilitation covering a survey, diagnosis, evaluation, and repair. Particularly for the Dome, which has high historical value and is important as a tourism resource, special evaluation criteria that fully take the characteristics of the structure and environmental conditions into consideration are required. This paper discusses a series of ideas that provided the basis for realizing the repair work, which is still underway. The discussed topics include basic ideas related to 1) inspection and diagnosis methods for the Dome; 2) evaluation of the structural members with five deterioration grades; 3) repair and prevention methods particularly suitable for a civil engineering heritage; and 4) execution of repair and prevention to enhance the durability of the Dome.