1. College of Civil and Transportation Engineering, Hohai Univ., Xikang Road 1#, Nanjing, Jiangsu, P.R. China 210098 (corresponding author). E-mail: xhj1218@126.com
2. College of Civil and Transportation Engineering, Hohai Univ., Xikang Road 1#, Nanjing, Jiangsu, P.R. China 210098.
3. Senior engineer, Project Quality Supervision Bureau of Jiangsu Province, Transport Dept. of Jiangsu Province, Shengzhou Road 16#, Nanjing, Jiangsu, P.R. China 210001.