Abstract
In the gravity-type quay wall supporting the earth pressure behind the structure by the self-weight, an increase of the horizontal earth pressure due to liquefaction result in damage of the caisson. It is predicted that further damage will be occurred due to the tsunami acting on the quay wall damaged by the preceding earthquake. As a countermeasure against the quay damage, a method of solidifying the back-filling layer behind the caisson has been proposed. In this research, the seismic response of gravity-type quay wall with improved backfill has been investigated by experimental simulation using geotechnical centrifuge. As a result, it was confirmed that the displacement of the caisson can be reduced by solidifying the backfill and a further effect can be expected by combining the improved backfill and the caisson.