1. Professor, Institute of Geotechnical Engineering, Transportation College, Southeast Univ., Nanjing 210096, P.R. China (corresponding author).
2. Professor, Institute of Geotechnical Engineering, Transportation College, Southeast Univ., Nanjing 210096, P. R. China.
3. Professor, Dept. of Civil Engineering, School of Naval Architecture, Ocean, and Civil Engineering, Shanghai Jiao Tong Univ., Shanghai 200030, P. R. China.
4. Assistant Professor, Dept. of Civil Engineering, Saga Univ., Saga 840-8502, Japan.