1. School of Architecture and Transportation Engineering, Guilin University of Electronic Technology, Guilin541004, P. R. China
2. Guangxi Key Laboratory of Geomechanics and Geotechnical Engineering, Guilin University of Technology, Guilin541004, P. R. China
3. Guangxi Key Laboratory of Geomechanics and Geotechnical Engineering, College of Civil Engineering and Architecture, Guilin University of Technology, Guilin541004, P. R. China
4. State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan, Hubei430071, P. R. China