混凝土真实细观模型的生成及氯离子传输的数值模拟
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TU528

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山东省重点研发计划(2018GHY115020);国家自然科学基金(U1806225)


Generation of real mesoscopic model of concrete and numerical simulation of chloride ions transportation
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    摘要:

    基于改进的遗传算法和8邻域边界跟踪法,对混凝土断面的数字图像进行处理,得到二值图像并提取粗骨料的边界坐标;根据提取的坐标编写程序,生成浆体集料界面过渡区(ITZ),得到真实的混凝土细观模型;将得到的混凝土细观模型导入COMSOL软件,模拟海洋水下区氯离子侵入混凝土内部过程,得到不同时刻混凝土内部氯离子浓度云图。研究结果表明:使用的建模和模拟方法所得结果与长期实海暴露混凝土实验结果一致,可以用来研究和评价海洋环境下混凝土的耐久性能;ITZ的存在会加速氯离子向混凝土内部扩散,其厚度越大,扩散过程越快,界面区厚度增大1倍,混凝土表观氯离子扩散系数增大12.3%;对比真实混凝土细观模型与参数化生成的圆形随机骨料模型中氯离子传输模拟结果发现,圆形随机骨料模型中氯离子的浓度总是小于真实细观模型中氯离子的浓度。

    Abstract:

    Based on the improved genetic algorithm and 8 neighborhood boundary tracking method, this paper adopts the real concrete section digital image to obtain binary image and extract the boundary coordinates of coarse aggregate. According to the extracted coordinates, a program was directly compiled to generate ITZ, and the real concrete mesoscopic model was obtained. Then, the obtained concrete mesoscopic model was imported into COMSOL software to simulate the process of chloride ions transporting the concrete in the underwater area of the ocean, and the cloud chart of chloride ions concentration in the concrete at different time was obtained. The results show that the modeling and simulation methods used in this paper are consistent with the experimental results of long-term exposed concrete in sea, which can be used to study and evaluate the durability of concrete under marine environment. The presence of the ITZ will accelerate the diffusion of chloride ions into the concrete. The greater the thickness is, the faster the diffusion process will be. The thickness of the interface area will double, and the apparent chloride ion diffusion coefficient of concrete will increase by 12.3%. By comparing the chloride ion transport simulation results of the real concrete mesoscopic model and the circular random aggregate model generated by parametric generation, it is found that the concentration of chloride ions in the circular random aggregate model is always smaller than that in the real microscopic model.

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李宁,金祖权,于泳,叶守杰.混凝土真实细观模型的生成及氯离子传输的数值模拟[J].土木与环境工程学报(中英文),2019,41(6):71-79.

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  • 收稿日期:2019-03-11
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  • 在线发布日期: 2019-12-12
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