RESEARCH ON CONCRETE DURABILITY OF MULTI-PILE CAP IN WIND POWER PROJECTS UNDER A FREEZE-THAW ENVIRONMENT IN THE COAST OF NORTH CHINA

The physical and engineering properties of concrete pile cap are known to be affected by the aggressive ocean environment and the freeze-thaw effects, which are commonly encountered in wind power projects in shallow waters in Northern China. In this research, compressive strength tests and flexural strength test have been carried out under simulated ocean conditions with the freeze-thaw cycles and sodium chloride solution immersion. In addition, rebar Pulling tests are performed to enhance the understanding of the impact on the bond strength of different grade of concrete due to the freeze-thaw cycles and chloride exposure. The degradation mechanism subject to the combined effect of freeze-thaw cycles and Chlorine ion are further studied using the ultrasonic testing technique. In the end, the paper presents finite element analyses conducted to model structural behavior of pile cap operating conditions. The study may provide references to wind power projects under similar operating environment in freeze-thaw waters in Northern China.