1. Associate Professor, Institute of Geotechnical Engineering, School of Highway Engineering, Chang’An Univ., Xi’an 710064, P.R. China.
2. Professor, School of Civil Engineering and Mechanics, Huazhong Univ. of Science and Technology, Wuhan 430074, P.R. China (corresponding author).
3. Senior Engineer, Guizhou Electric Power Design and Research Institute, Guiyang 550002, P.R. China.
4. Professor, Institute of Geotechnical Engineering, School of Highway Engineering, Chang’an Univ., Xi’an 710064, P.R. China.