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为了深入研究腐蚀环境中锚固结构腐蚀损伤发展规律,考虑氧气浓度与局部腐蚀的影响,在室内开展腐蚀环境下预应力锚筋浸泡腐蚀试验及腐蚀试样材料力学性能试验。腐蚀试验过程中进行电化学测试与筋材局部应变监测,基于试验结果分析预应力、环境pH值、环境含氧浓度等因素与锚筋腐蚀速率、外观损伤特性、单位长度损失量、力学特性之间的关系,并探讨不同含氧环境下预应力锚筋局部应变发展规律。试验结果表明:(1)弱酸环境中酸性越强锚筋腐蚀速率越快;(2)氧气对预应力锚筋腐蚀促进作用显著,环境氧气浓度越高腐蚀速率越大,但超过一定值后增大现象不明显;(3)试验条件下,随着通氧速率增大,锚筋单位长度腐蚀量增加;(4)锚筋极限伸长率、极限抗拉载荷、弹性模量3个力学指标随着环境氧含量增大有明显的下降现象,且在同一通氧速率下,极限伸长率损失率最大,弹性模量损失率次之,而极限承载力损失率最小;(5)局部腐蚀使受腐蚀截面力心发生偏移,不同含氧环境下锚杆表面应变发展迥异,富氧侧应变呈拉应变增大趋势,而缺氧侧则由拉应变向压应变发展。
In order to study deeply the development of corrosion damage of anchorage structure in corrosive environment and considering the influence of oxygen concentration and local corrosion, the immersion corrosion test of prestressed tendon in corrosive environment and the mechanical property test of corroded specimen were carried out indoors. Electrochemical tests and local strain monitoring of tendons were carried out during the corrosion test. Based on the test results, the factors such as the prestress, the pH value of the environment and the oxygen concentration in the environment were analyzed. The corrosion rate, appearance damage, loss per unit length, mechanical properties And discuss the law of local strain of prestressed tendons in different oxygen environments. The results show that: (1) The stronger acidity in weak acid environment is, the faster the corrosion rate of anchorage tendons is; (2) Oxygen promotes the corrosion of prestressed anchor tendons remarkably. The higher the ambient oxygen concentration is, the higher the corrosion rate is. Large-scale phenomenon is not obvious; (3) under the experimental conditions, the corrosion rate per unit length of tendon increases with the increase of oxygen rate; (4) The ultimate tensile elongation, ultimate tensile load and elastic modulus With the increase of oxygen content in the environment, there is a clear drop phenomenon. Under the same oxygen rate, the ultimate elongation loss rate is the highest, followed by the elastic modulus loss rate, while the ultimate bearing capacity loss rate is the lowest. (5) The stress of the corroded section is deviated. Under different oxygen environments, the surface strain of rock bolt develops very different. The tensile strain at the oxygen-enriched side increases with the increase of tensile strain, while that at the anoxic side increases from the tensile strain to the compressive strain.