1. College of Civil Engineering, Hunan Univ., Changsha 410082, China.
2. Associate Professor, College of Civil Engineering, Hunan Univ., Changsha 410082, China (corresponding author).
3. Professor, College of Civil Engineering, Hunan Univ., Changsha 410082, China.
4. National Engineering Laboratory for Technology of Geological Disaster Prevention in Land Transportation, Southwest Jiaotong Univ., Chengdu 611756, China.
5. Professor, Dept. of Bridge Engineering, Southwest Jiaotong Univ., 111 Section of the Northbound 1, Second Ring Rd., Chengdu 610031, China.