| To clarify the subsidence conditions of ground behind seawalls，cases of damage at harbors and fishing ports under the administration of the Hokkaido Regional Development Bureau were examined，and the causes of damage were classified．The results showed that the main factor was the removal of reclaimed sand by suction forces caused by damage in geotextile sheet and joint fillers．It was also found that seawalls tended to be more vulnerable to these suction forces ten years after construction compared with mooring wharfs．Moreover、 paying attention to the damage cases of geotextile sheet on seawalls which had most damage number of cases、 the subsidence damage factor was examined based on cross-sectional configuration or design external force. |
