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The Okinawa General Bureau of Cabinet Office has been performed various environmental investigations to realize coexistence of coral reef and port construction. It should be necessary to utilize the data provided by the investigation effectively. However, there was not a unified guideline by the past investigation. There was the case that an investigation item or precisions were different on each investigation. There was also the grasp of the general comparison and evaluation of the investigated data. Therefore we planed to make unified guideline of investigation methods of coral reef at the port of Okinawa. "The guideline of investigation methods of coral reef at the ports in Okinawa" was published in March 2007.

This report describes repair methods applied to the bridge piers (Nos. P7&P8) damaged due to chloride induced corrosion together with seismic strengthening applied in 2001-2002,It is required that economical concrete mixes and construction methods,which are applicable to the concrete structures damaged due to chloride induced corrosion under any climatic environmentwill be developed. (selection of section recovery material,deal with change of concrete,) Key Words chioride induced corrosion, bridge pier, investigation, section recovery, Corrosion of redar,polymer cememt concrete

Naha immersed tunnel will cross under the port entrance of the Naha wharf, Okinawa, where large liner ships are in service. Fluid power caused by the large vessel was expected to influence strongly against the stability of the tunnel element during construction. In this report, the stability of the element is investigated through threedimensional numerical simulation, in which speed of the large vessel is assumed to be constant. It is confirmed from the simulation that a large up-lift force is generated by the large vessel when it passes above the element, and that increase of navigation speed reduces the stability of the element against sliding.