1. College of Civil Engineering, 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, Fujian University of Technology, Fuzhou, P.R. China.
3. Priority Research Centre for Geotechnical Science and Engineering, Faculty of Engineering and Built Environment, The University of Newcastle, Callaghan, NSW, Australia.