1. Key Laboratory of New Technology for Construction of Cities in Mountain Area (Chongqing University), Ministry of Education, Chongqing, P. R. China.
2. School of Civil Engineering, Chongqing University, Chongqing, P. R. China.
3. ARC Centre of Excellence for Geotechnical Science and Engineering, Faculty of Engineering and Built Environment, The University of Newcastle, Callaghan, NSW, Australia.
4. College of Civil Engineering, Hohai University, Nanjing, P. R. China.