疲劳荷载与氯盐耦合作用下混凝土中氯离子扩散行为的试验研究

发布时间：2018-03-14 13:35

本文选题：混凝土　切入点：疲劳　出处：《实验力学》2017年04期 　论文类型：期刊论文

【摘要】：混凝土桥梁在服役过程中经常同时承受疲劳荷载和氯离子侵蚀,但现有研究多未考虑疲劳和氯离子侵蚀的耦合作用。本文研究了疲劳荷载与氯盐侵蚀耦合作用下混凝土中氯离子的扩散行为,并运用超声检测表征混凝土的疲劳损伤,以建立疲劳损伤与氯离子扩散性能之间的关系。研究结果表明:随着疲劳压应力水平提高,超声参数表征的混凝土损伤值也逐渐增大;应力水平低于0.4时,不同疲劳应力水平对混凝土中氯离子浓度分布没有明显影响,氯离子扩散系数甚至略有减小,这应是应力水平较低时混凝土中微孔隙和裂缝被压缩而降低了氯离子的扩散能力;应力水平为0.5及0.6时,混凝土中氯离子浓度显著提高,扩散系数明显增大,并且与应力水平呈正相关;超声参数表征的混凝土损伤与氯离子渗透性的发展趋势不一致,表明由于混凝土内部缺陷分布的不均匀性使得超声技术难以定量表征荷载引起的混凝土损伤。
[Abstract]:Concrete bridges are often subjected to both fatigue load and chloride erosion during service. In this paper, the diffusion behavior of chloride ions in concrete under the coupling of fatigue load and chloride erosion is studied, and the fatigue damage of concrete is characterized by ultrasonic detection. In order to establish the relationship between fatigue damage and chloride diffusion property, the results show that the damage value of concrete characterized by ultrasonic parameters increases with the increase of fatigue compressive stress level, and when the stress level is lower than 0.4, Different fatigue stress levels have no obvious effect on the chloride concentration distribution in concrete, and the chloride diffusion coefficient even decreases slightly, which is due to the reduction of chloride diffusion capacity due to the compression of micro-pores and cracks in concrete with lower stress level. When the stress levels are 0.5 and 0.6, the chloride concentration in concrete increases significantly, the diffusion coefficient increases obviously, and it is positively correlated with the stress level, and the damage of concrete characterized by ultrasonic parameters is not consistent with the development trend of chloride ion permeability. It is shown that ultrasonic technique is difficult to quantitatively characterize concrete damage caused by load due to the uneven distribution of internal defects in concrete.
【作者单位】：长沙理工大学土木与建筑学院;长沙理工大学南方地区桥梁长期性能提升技术国家地方联合工程实验室;
【基金】：国家自然科学基金(51578078) 国家“973”计划课题(2015CB057701) 长沙市科技计划(K1508020-31) 长沙理工大学土木工程优势特色重点学科创新性项目(16ZDXK10)
【分类号】：TU528

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