锈蚀钢筋混凝土方桩水平承载性能退化规律

Degradation Law of Lateral Bearing Behavior of Corroded Reinforced Concrete Square Piles

为研究锈蚀钢筋混凝土方桩的水平承载性能的退化规律,根据Fick第二定律,建立氯离子在钢筋混凝土方桩中的扩散模型,并根据初始和边界条件,求得扩散方程的解析解。依据厚壁圆筒模型,推导了钢筋混凝土方桩保护层锈胀开裂时的钢筋临界锈蚀深度。基于Faraday定律,对钢筋混凝土方桩钢筋的锈蚀深度和保护层锈胀开裂时间进行预测。在此基础上,通过引入钢筋混凝土方桩桩身抗弯刚度退化系数,进而对海洋环境下锈蚀钢筋混凝土方桩的水平承载性能进行分析。结果表明:海洋环境下由于氯离子的扩散引起的钢筋锈蚀对于钢筋混凝土方桩的水平承载性能有显著影响;随着暴露时间的增加和暴露条件的恶劣,桩身抗弯刚度明显退化,桩身负剪力、桩身水平位移和桩身弯矩的最大值逐渐增大;荷载条件相同情况下,与桩身剪力以及弯矩相比较,暴露时间对于桩身的水平位移所起到的作用更为明显。研究成果可为海洋环境下钢筋混凝土桩基础的设计提供参考。

To study the degradation law of lateral bearing behavior of corroded RC(reinforced concrete)square piles,the governing model of chloride diffusion into RC square pile was established based on Fick’s second law.According to the initial and boundary conditions,the analytical solution of chloride diffusion equation was presented.Based on Faraday’s law,the corrosion depth and the time for corrosion-induced cover cracking in RC square pile were estimated.On this basis,the degradation coefficient of the bending stiffness of the RC square pile was introduced,and the lateral bearing behavior of corroded RC square piles exposed to marine environment was further analyzed.The analysis results illustrated that the chloride-induced reinforcement corrosion had a significant influence on the behavior of laterally loaded RC square piles exposed to marine environments.The bending stiffness of the RC square pile decreased obviously with the increase of the exposed time and deterioration of exposure condition;while the maximum negative shear force,the lateral deflection and the bending moment increased with the increase of the exposed time.Given the same load,the exposed time posed a more obvious impact on the horizontal displacement of pile than on shear force and bending moment.The research findings offer reference for the design of RC pile foundation subjected to marine environment.