氯离子侵蚀钢筋混凝土管桩的使用寿命预测

Service Life Prediction of Reinforced Concrete Pipe Pile Due to Chloride Ion Corrosion

摘要:

基于氯离子侵蚀引起的钢筋锈蚀机理，将钢筋混凝土管桩的使用寿命分为2个阶段，锈蚀初始阶段和裂缝扩展阶段.依据Fick第二定律和Faraday定律，分别建立了氯离子在钢筋混凝土管桩中的扩散方程和氯离子侵蚀引起的钢筋锈蚀模型，通过确定临界氯离子浓度和钢筋临界锈蚀深度，分别对锈蚀初始阶段时间和裂缝扩展阶段时间进行了预测.并在此基础上，进一步分析了表面氯离子浓度、扩散系数、保护层厚度、钢筋直径、体积膨胀率以及抗拉强度与弹性模量的比值等因素对钢筋混凝土管桩使用寿命的影响.分析结果表明，随着表面氯离子浓度、扩散系数、钢筋直径和体积膨胀率的增大，管桩的使用寿命减小；随着保护层厚度和抗拉强度与弹性模量的比值的增大，管桩的使用寿命增大.

Abstract:

According to the chloride induced reinforcing steel corrosion mechanism, the service life of reinforced concrete (RC) pipe piles can be divided into two phases, i.e., the corrosion initiation phase and the crack propagation phase. Based on Fick’s second law and Faraday’s law, the governing equation of chloride diffusion into RC pipe pile was established and a chloride induced reinforcement corrosion model in RC pipe pile was developed. The corrosion initiation phase time and crack propagation phase time were predicted by determining the critical chloride concentration and the critical attack penetration depth, respectively. Then the effect of surface chloride ion concentration, diffusion coefficient, cover thickness, reinforcement diameter, volume expansive ratio and the ratio of tensile strength to elastic modulus on service life of RC pipe piles was further analyzed, respectively. The analysis results indicate that the service life of RC pipe pile decreases with the increasing of surface chloride ion concentration, diffusion coefficient, reinforcement diameter and volume expansive ratio, while the service life of RC pipe pile increases with the increasing of cover thickness and the ratio of tensile strength to elastic modulus.