The dynamic response of a caisson-type structure resting on pile foundation loaded by waves was numerically evaluated by FEM analysis in order to investigate the feasibility of a pile with an expanding end to support such offshore structure foundations. The caisson-type structure, e.g. caisson breakwater, caisson-type seawall, dike, dolphin, quaywall or jetty, was assumed to be a linear and elastic solid and the soil was assumed to be a linear, elastic and permeable medium to simulate a normally consolidated soil. The displacement and the pore water pressure around the piles were numerically estimated from the viewpoints of the number of piles under the caisson, the distance between piles and the connection between the caisson and piles. This type of pile foundation prevents the generation of excess pore water pressure beneath the caisson. The connection between the caisson and piles is considerable with uneven sinking and rocking.
Port structures such as quays and jetties are important for goods movement from/to overseas. The importance of port structures increases especially after disastrous earthquakes. A severe shock of earthquake crushes infrastructures such as transportation, telecommunication, lifelines and buildings. The disaster rehabilitation works need the infrastructures described above to supply (1) foods and water; (2) emergency goods; (3) construction materials; (4) workers; (5) accommodations and so on. It takes a long time more than several years to complete the restoration of such infrastructures. Even their emergency rehabilitation takes considerable time too before they will be available to use. The mass transportation by the shipping becomes the principal means to supply a large amount of relief goods and commodities. According to circumstances, the shipping is utilized as accommodations or an emergency department for the area stricken by earthquake. And the shipping is also available for the emergency evacuation. Thus, the reasonable seismic design method is required for port structures e.g. quay and jetty.