1. Ph.D. Student, Dept. of Civil Engineering, Shanghai Jiao Tong Univ., 800 Dongchuan Rd., Shanghai 200240, China.
2. Senior Engineer, Shanghai Tunnel Engineering Co., Ltd., 118 Dalian Rd., Shanghai 200082, China.
3. Graduate Student, Dept. of Civil Engineering, Shanghai Jiao Tong Univ., 800 Dongchuan Rd., Shanghai 200240, China.
4. Professor, Dept. of Civil Engineering, Shanghai Jiao Tong Univ., 800 Dongchuan Rd., Shanghai 200240, China (corresponding author).