既有钢筋混凝土码头保护层锈胀开裂计算时长对比

Propagation assessment of existing concrete dock based on concrete cover corrosion-crack

摘要:

为评估北部湾某在役混凝土码头的耐久性状态，预测其剩余使用寿命.本文基于现场检测结果，通过确定性预测模型和随机性预测模型，对比分析了该混凝土码头的保护层锈胀开裂时长.结果表明，在确定性预测模型中，根据列举的8种模型计算得到保护层锈胀开裂时长为2.09~22.77 a.对于较为恶劣的氯离子侵蚀环境，学者和工程师给出的经验值2~5 a是合理的.在随机性预测模型中，本文考虑了裂缝宽度限值的随机性以及腐蚀速率时变特性，计算得到保护层锈胀开裂时长约为12.7 a，该值与确定性模型的计算结果相吻合.裂缝宽度限值和腐蚀速率对保护层锈胀开裂时长的预测有着显著影响.当腐蚀速率从0.5 μA/cm²上升到1.0 μA/cm²时，保护层锈胀开裂时长减少了14.75 %；而当裂缝宽度限值从0.15 mm增加到0.5 mm时，保护层锈胀开裂时长则增加了39.13 %.研究显示被检测混凝土码头能很好地满足设计使用年限要求.

Abstract:

To assess the durability status and remaining service life of existing concrete dock located at Beibu Gulf, the propagation phase was evaluated based on the in situ test data and concrete cover corrosion-crack model. The results indicate that the propagation phase will last about 2.09-22.77 years based on eight deterministic models. The empirical values of 2-5 years, recommended by scholars and engineers, would be more reasonable when the RC structures were exposed to harsh corrosion environment. According to the probabilistic model, the uncertainty of limit crack width and time-dependent characteristic of the corrosion rate were taken into considered, the propagation phase equated to 12.7 years, which was fitted with the deterministic models. The limit crack width and corrosion rate significantly affect the assessment of the propagation phase. When the value of corrosion rate increases from 0.5 to 1.0 μA/cm², the value of the propagation phase decreases by 14.75 %; and the value of the propagation phase increases by 39.13 % when the value of limit crack width rises from 0.15 to 0.50 mm. The study shows that the tested concrete dock can meet the requirement of design service life.