1. Researcher, Geotechnical Research Institute, Hohai Univ., Nanjing 210098, China; and Lecturer, Faculty of Transportation Engineering, Hochiminh Univ. of Transportation, Hochiminh City 717208, Vietnam (corresponding author).
2. Professor, Geotechnical Research Institute, Hohai Univ., Nanjing 210098, China.
3. Associate Professor, Geotechnical Research Institute, Hohai Univ., Nanjing 210098, China.