1. Associate Professor, Dept. of Geotechnical Engineering, Tongji Univ., 1239 Siping Rd., Shanghai 200092, China (corresponding author).
2. Graduate Student, Dept. of Geotechnical Engineering, Tongji Univ., 1239 Siping Rd., Shanghai 200092, China.
3. Senior Engineer, China Railway No. 4 Survey and Design Group Co., Ltd., 745 Peace Ave., Wuhan, Hubei Province 430063, China.