1. Chf., Soil Mech. Lab., Geotech. Engrg. Div., Port and Harb. Res. Inst., 3-1-1 Nagase, Yokosuka 239, Japan.
2. Prof., New Technol. and Res., Dept. of Transp., State of California, 5900 Folsom Blvd., Sacramento, CA 95819; formerly, Port and Harb. Res. Inst., and Tech. Res. Inst., TOA Corp., Japan. E-mail: porbaha@ hotmail.com (corresponding author).
3. Res. Engr., Tech. Res. Inst., TOA Corp., 1-3 Anzen-cho, Tsurumi-ku, Yokohama 230, Japan.