1. College of Civil Engineering, Chongqing Jiaotong University, Chongqing 400074, P. R. China
2. College of Environment and Civil Engineering, Chengdu University of Technology, Chengdu 610059, Sichuan, P. R. China
3. State Key Laboratory of Geohazard Prevention and Geoenvironment Protection, Chengdu University of Technology, Chengdu 610059, Sichuan, P. R. China
4. Department of Civil Engineering, Xihua University, Chengdu 611930, Sichuan, P. R. China