1. Ph.D. Candidate, Institute of Geotechnical Engineering, Hunan Univ., Changsha 410082, PR China.
2. Associate Professor, Institute of Geotechnical Engineering, Hunan Univ., Changsha 410082, PR China.
3. Postdoctoral Fellow, College of Civil Engineering, Hunan Univ., Changsha 410082, PR China (corresponding author).
4. Professor, Institute of Geotechnical Engineering, Hunan Univ., Changsha 410082, PR China.