1. Associate Professor, Dept. of Civil Engineering, Shanghai Jiao Tong Univ., Shanghai 200240, China.
2. Assistant Professor, Dept. of Civil Engineering and Engineering Mechanics, Univ. of Arizona, Tucson, AZ 85721 (corresponding author).
3. Graduate Student, Dept. of Civil Engineering, Shanghai Jiao Tong Univ., Shanghai 200240, China.
4. Deputy Chief Engineer, Shanghai Tunnel Engineering Co., Ltd, Shanghai 200082, China.
5. Professor, Dept. of Civil Engineering, Shanghai Jiao Tong Univ., Shanghai 200240, China.