1. Ph.D. Candidate, Nottingham Centre for Geomechanics, The Univ. of Nottingham, University Park, Nottingham NG72RD (corresponding author).
2. Professor, School of Civil Engineering, Wuhan Univ., Wuhan Univ. (North gate), WuChang district, Wuhan 430072.
3. Doctor, School of Civil Engineering, Wuhan Univ., Wuhan Univ. (North gate), WuChang district, Wuhan 430072.