1. School of Civil Engineering, Tianjin University, Tianjin, P.R. China;
2. Key Laboratory of Coast Civil Structure Safety of Ministry of Education, Tianjin University, Tianjin, P.R. China;
3. CNPC Engineering Technology R&D Company Limited, Beijing, P.R. China;
4. College of Petroleum Engineering, China University of Petroleum (Beijing), Beijing, P.R. China