1. Lecturer, Dept. of Civil Engineering, Univ. of Shanghai for Science and Technology, 516 Jungong Rd., 200093 Shanghai, P.R. China.
2. Professor of Civil Engineering, Centre for Geomechanics and Railway Engineering, Faculty of Engineering, Univ. of Wollongong, Wollongong, NSW 2522, Australia (corresponding author).
3. Research Fellow, Centre for Geomechanics and Railway Engineering, Faculty of Engineering, Univ. of Wollongong, Wollongong, NSW 2522, Australia.
4. Emeritus Professor of Civil Engineering, Centre for Geotechnical Science and Engineering, Faculty of Engineering and Built Environment, Univ. of Newcastle, Newcastle, NSW 2308, Australia.
5. Professor of Civil Engineering, Univ. of Shanghai for Science and Technology, 516 Jungong Rd., 200093 Shanghai, P.R. China.