基于实际工程预应力锚索面临的复杂多因素腐蚀环境,为了更真实全面地掌握其材料腐蚀耐久性及规律,开展了pH值、侵蚀性离子(Cl-、SO42-)、近真实荷载应力耦合作用下的锚索室内加速腐蚀试验。监测了运行中锚索钢绞线锚固荷载变化特性,采用材料微观表征和力学性能测试方法系统研究了锚索钢绞线表观腐蚀演化、产物结构特征以及单位长度质量损失、抗拉强度损失率等时变规律,并分析揭示了相应的腐蚀反应机理。研究表明,荷载应力对钢绞线腐蚀程度有一定加剧作用,与无应力状态下相比,高应力条件下钢绞线抗拉强度损失率显著增大。SO42-与Cl-同时存在比SO42-或Cl-单一存在更加速了钢绞线腐蚀,碱性溶液中腐蚀程度相对低于酸性溶液中的腐蚀程度。加速腐蚀试验1 a后钢绞线单位长度质量损失最高可达0.5 g/cm,抗拉强度损失率最高达到近50%。该研究可为评估预测真实服役环境中锚索腐蚀耐久性寿命提供科学依据和数据支撑。
Abstract
The aim of this research is to truly and comprehensively understand the corrosion durability of anchor cable serving in the complex multi-factor corrosion environment. Indoor accelerated corrosion test of prestressed anchor cable under the coupling action of pH value, Cl-, SO42-, and stress near real load was carried out. The change characteristics of anchoring load of the anchor steel strand during the test were monitored. The appearance development of steel strand corrosion, the structural characteristics of corrosion products, and the time-dependent variation of mass loss per unit length and tensile strength loss rate were systematically studied by using material microscopic characterization method and mechanical property testing. The corresponding corrosion reaction mechanism was also analyzed. Results reveal that load stress intensifies the corrosion of steel strand. Compared with that in stress-free condition, the loss rate of tensile strength of steel strand in high stress condition is significantly higher. The simultaneous presence of SO42- and Cl- accelerates the corrosion of steel strand more than the single presence of SO42 or Cl-. Moreover,the corrosion degree in alkaline solution is relatively lower than that in acidic solution. After one year of accelerated corrosion test, the maximum mass loss per unit length of steel strand can reach 0.5 g/cm, and the maximum loss rate of tensile strength can reach nearly 50%. The research findings offer scientific basis and data support for evaluating and predicting the corrosion durability of anchor cable in real service environment.
关键词
锚索 /
腐蚀 /
多因素耦合 /
演变规律 /
加速试验
Key words
anchor cable /
corrosion /
coupling factors /
evolution law /
accelerated test
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基金
中国长江三峡集团有限公司科研项目(201903073);新疆兵团重点领域科技攻关计划项目(2020AB010);国家自然科学基金青年基金项目(52009010);中央级公益性科研院所基本科研业务费项目(CKSF2023317/CL)
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