海工混凝土环境损伤力学研究进展

ADVANCES OF ENVIRONMENT DAMAGE MECHANICS IN MARINE ENGINEERING CONCRETE

  • 摘要: 海工混凝土结构的安全性与耐久性是值得力学学科关注的重要问题。钢筋混凝土是由素混凝土基体和加强钢筋组成的复合材料。在海水中的氯离子腐蚀下钢筋会发生锈蚀,而在海洋环境的各种化学因素和物理因素作用下会导致素混凝土基体中的微裂纹成核与长大。腐蚀损伤会导致氯离子扩散系数增加,钢筋锈蚀加速,最终导致混凝土结构的安全性与耐久性降低。海工混凝土的损伤由化学因素和物理因素所诱发,化学因素包括碳化和侵蚀性离子(氯离子、硫酸根离子和镁离子)的攻击,而物理因素包括温度、湿度、波浪冲蚀和紫外辐射等。本文介绍了海工混凝土环境损伤力学的研究进展,首先讨论了环境损伤的诱发机理,然后介绍了环境损伤力学的理论模型,包括钢筋坑蚀的概率模型、硫酸盐腐蚀下混凝土损伤演化的模型和断裂韧性演化模型、波浪冲蚀模型等。腐蚀损伤对氯离子扩散的耦合作用也进行了评述,强调了如果不考虑腐蚀损伤的影响,关于氯离子在混凝土中扩散的分析结果有可能是错误的。最后,提出了几个未来需要解决的重要问题。

     

    Abstract: Safty and durability of marine engineering concrete structures are important concerns for mechanics researchers. Reinforced concrete is a composite of concrete matrix and reinforced steel bars. Steel bars could be corrosed due to attack by chloride ions in seawater. Also, microcracks’ nucleation and growth may occur in concrete matrix under the action of various chemical and physical factors. Such a corrosion damage leads to the increase of diffution coefficient of chloride ions in concrete and the accelerated corrosion of steel bars, and this eventually reduces the safety and durability of concrete. The damage of marine engineering concrete is induced by chemical factors and physical factors. Chemical factors include carbonization and attack of corrosive ions (such as chloride ions, sulfate ions, and magnesian ions), whereas physical factors include temperature, humidity, wave erosion, and ultraviolet radiation. In this paper, some advances on the research of damage mechanics in marine engineering concrete are inrtoduced. The mechanism of damage in concrete due to environment factors is firstly discussed, and then some theoretical models of damage mechanics are recommended, including the probability model of pit corrosion damage in steel bar, the evolution model of fracture toughness and cracks of concrete matrix under sulfate attack, wave erosion model of concrete structures, etc. Subsequently, the effect of corrosion damage on the diffusion of chloride ions is illustrated, and it is emphasized that the analysis on the diffusion of chloride ions may be uncorrect if the corrosion damage is not taken into account. Finally, some important problems needing to be solved in the future are presented.

     

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