1. Lecturer, School of Resources and Environmental Engineering, Wuhan Univ. of Science and Technology, Wuhan, Hubei 430081, P.R. China; Lecturer, Key Laboratory of Rock Mechanics in Hydraulic Structural Engineering, Ministry of Education, Wuhan Univ., Wuhan 430072, P.R. China (corresponding author).
2. Professor, School of Civil Engineering, Wuhan Univ., Wuhan 430072, P.R. China; Professor, School of Civil Engineering and Architecture, Nanchang Univ., Jiangxi 330031, P.R. China.
3. Professor, School of Resources and Environmental Engineering, Wuhan Univ. of Science and Technology, Wuhan, Hubei 430081, P.R. China.