1. School of Civil Engineering, Southwest Jiaotong University, Chengdu, Sichuan, China
2. Key Laboratory for Highway Engineering of Sichuan Province, Southwest Jiaotong University, Chengdu, Sichuan, China
3. School of Civil Engineering, Faculty of Engineering and Physical Sciences, University of Leeds, Leeds, UK
4. School of Civil Engineering, Lanzhou Jiaotong University, Lanzhou, Gansu, China