In 1980, the Port and Harbour Research Institute (PHRI) constructed a geotechnical centrifuge (Mark I) of 3.8m effective radius. Since then PHRI Geotechnical Group has conducted more than 1300 centrifuge operations and has published nearly 60 papers related to centrifuge model tests.
　Since 1989, undesirable vibrations of the concrete pit floor have frequently occurred during high speed operation. This phenomenon was due to the progress of cracks in the concrete pit floor. After detailed investigation, maximum operative acceleration was reduced below 50g for safety reasons.
　And PHRI also decided to construct a new centrifuge, Mark II centrifuge adjacent to the existing centrifuge facility in 1989 and completed in 1995. Many research projects related to centrifuge model testing will also be performed by the Mark II centrifuge.
　This paper briefly describes development of the PHRI Mark II centrifuge facilities and data acquisition systems. Current research subjects studied are also briefly described to demonstrate usefulness of this modeling technique and ability of our centrifuge facilities.