1. Lecturer, School of Civil Engineering, National Huaqiao Univ., 668 Jimei Ave., Jimei District, Xiamen, Fujian Province, 361021, China; formerly, Ph.D. Student, Nottingham Centre for Geomechanics, Faculty of Engineering, Univ. of Nottingham, University Park, Nottingham NG7 2RD, U.K.
2. Professor of Geotechnical Engineering, Nottingham Centre for Geomechanics, Faculty of Engineering, Univ. of Nottingham, University Park, Nottingham NG7 2RD, U.K.
3. Associate Professor, Nottingham Centre for Geomechanics, Faculty of Engineering, Univ. of Nottingham, University Park, Nottingham NG7 2RD, U.K. (corresponding author).
4. Lecturer, Nottingham Centre for Geomechanics, Faculty of Engineering, Univ. of Nottingham, University Park, Nottingham NG7 2RD, U.K.