摘要
【目标】研究干湿循环作用下多裂缝参数对预应力构件锚固端非饱和开裂混凝土中氯离子传输的影响规律,并为临海附近预应力构件耐久性设计提供更精确的理论计算方法。【方法】首先以预应力混凝土梁作为试验梁,采用裂缝预制的方法代替实际裂缝,针对不同裂缝参数(宽度、数量、区域)对氯离子传输的影响开展试验研究;然后采用有限元软件建立考虑多裂缝参数的氯离子传输数值模型,并引入裂缝形态作为氯离子扩散修正系数;最后对比试验结果和模型计算结果,分析了裂缝间距、形态参数对氯离子传输的影响。【结果】裂缝数量对于混凝土中氯离子传输具有加速效应,且出现第一道裂缝时的加速效应最为强烈,但是裂缝达到3条后,裂缝数量将不再对同一侵蚀深度氯离子含量有影响。锚固区正面裂缝区域氯离子含量高于侧面的氯离子含量,且随着深度的增加,正面与侧面混凝土中氯离子含量差值范围在缩小。裂缝间距对于加速混凝土氯离子对流扩散的影响具有一定范围,深度大于20 mm时,同一深度内氯离子含量随裂缝间距的增大而下降,同时下降速率减小。当侵蚀深度大于15 mm时,矩形裂缝中氯离子含量最大,锯齿次之,V形裂缝最小,锯齿形和V形裂缝的不规则形态会减缓氯离子的传输过程。【结论】考虑裂缝宽度、深度、数量、间距和形状的氯离子传输模型是合理的,可以用于干湿交替作用下混凝土多裂缝区域氯离子传输的模拟与分析。
[Objective]The study investigated the influence of multi-fracture parameters on chloride ion transport in unsaturated cracked concrete at the anchorage end of prestressed components with wet-dry cycles.It aimed to provide more precise theoretical calculation method for the durability design of prestressed components near the sea.[Method]First,the pre-stressed concrete beam was used as the test beam.The prefabricated fractures were adopted to replace the actual fractures.The experimental study was carried out on the influence of different fracture parameters(e.g.,width,quantity and location)on chloride ion transport.Then,the finite element software was used to establish a numerical model of chloride ion transport considering multi-fracture parameters.The fracture morphology was introduced as the correction coefficient for chloride ion diffusion.Finally,the test results were compared with the model calculation results.The influence of fracture spacing and morphological parameters on chloride ion transport was analyzed.[Result]The number of fractures has an acceleration effect on chloride ion transport in concrete;and the acceleration effect is the most intense when the first fracture appears.However,the number of fractures will no longer affect the chloride content at the same erosion depth when the fractures reach 3 pieces.The chloride ion content in the fracture area on the front of anchorage zone is higher than that on the side.As the depth increases,the difference range of chloride ion contents in concrete on the front and side is narrowing.The influence of fracture spacing on accelerating chloride ions convective diffusion in concrete has a certain range.When the depth is greater than 20 mm,the chloride ion content at the same depth decreases with the increase of fracture spacing,while the decreasing rate is descent.When the erosion depth is greater than 15 mm,the chloride ion content in rectangular fractures is the largest,followed by serrated fractures,and the V-shaped fractures have the least.The irregular morphology of zigzag and V-shaped fractures will slow down the transport process of chloride ions.[Conclusion]The chloride ion transport model,considering the fracture width,depth,number,spacing and shape,is reasonable.It can be used for the simulation and analysis on chloride ion transport in multi-fracture areas of concrete under alternate dry-wet cycle.
作者
唐皇
彭建新
张建仁
程小康
周鹏程
TANG Huang;PENG Jianxin;ZHANG Jianren;CHENG Xiaokang;ZHOU Pengcheng(College of Civil Engineering,Hunan City University,Yiyang,Hunan 413000,China;Hunan Provincial Engineering Research Center for Development and Application of Ceramsite Concrete Technology,Yiyang,Hunan 413000,China;School of Civil and Environmental Engineering,Changsha University of Science and Technology,Changsha,Hunan 410114,China)
出处
《公路交通科技》
北大核心
2025年第8期110-121,共12页
Journal of Highway and Transportation Research and Development
基金
国家自然科学基金项目(52308125,52208166)。
关键词
桥梁工程
干湿循环
数值模拟
多裂缝
氯离子传输
bridge engineering
dry-wet cycle
numerical simulation
multi-fracture
chloride ion transport
