1. Head of Group, Soil Stabilization Group, Geotechnical Engineering Division, Port and Airport Research Institute, MPAT, Yokosuka, Japan (corresponding author: )
2. Director of Division, Geotechnical Engineering Division, Port and Airport Research Institute, MPAT, Yokosuka, Japan
3. Deputy Director, Ports and Harbours Bureau, Ministry of Land, Infrastructure, Transport and Tourism, Tokyo, Japan (Formerly of Coastal and Ocean Engineering Division, Port and Airport Research Institute, MPAT)