1. Professor, College of Civil Engineering, Guilin Univ. of Technology, Guangxi Key Laboratory of Geomechanics and Geotechnical Engineering, Guilin 541004, P.R. China.
2. Graduate Student, College of Civil Engineering, Guilin Univ. of Technology, Guangxi Key Laboratory of Geomechanics and Geotechnical Engineering, Guilin 541004, P.R. China.
3. School of Architecture and Transportation Engineering, Guilin Univ. of Electronic Technology, Guilin 541004, P.R. China (corresponding author).
4. Associate Professor, College of Civil Engineering, Guilin Univ. of Technology, Guangxi Key Laboratory of Geomechanics and Geotechnical Engineering, Guilin 541004, P.R. China.