1. Professor, Dept. of Civil Engineering, Saga Univ., 1 Honjo, Saga 840-8502, Japan (corresponding author).
2. Pro Vice-Chancellor, Faculty of Engineering and Built Environment, The Univ. of Newcastle, New South Wales 2308, Australia.
3. Principal, Institute of Soft Soil Engineering, Co., Ltd., Saga 840-0811, Japan.
4. Professor, School of Civil Engineering, Tongji Univ., 1239 Siping Rd., Shanghai 200092, China.