| 基于低场核磁共振技术高温水泥砂浆局部热损伤的研究 |
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| 引用本文： | 郝坤,宁麟,郭鸿雁,刘冒佚. 基于低场核磁共振技术高温水泥砂浆局部热损伤的研究[J]. 硅酸盐通报, 2022, 41(12): 4163-4171 |
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| 作者姓名： | 郝坤 宁麟 郭鸿雁 刘冒佚 |
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| 作者单位： | 招商局重庆交通科研设计院有限公司,重庆 400067;贵州大学土木工程学院,贵阳 550025;重庆市城市建设投资(集团)有限公司,重庆 400023 |
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| 基金项目： | 国家自然科学基金(52164001) |
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| 摘 要： | 为研究高温水泥砂浆在局部水冷作用后的损伤演化特征以及裂纹扩展情况,在水泥砂浆试件中部钻孔,将试件加热到200 ℃及400 ℃后向孔洞注水进行局部冷却。采用低场核磁共振技术(NMR)研究水泥砂浆试件在高温及局部水冷作用下的损伤行为。结果表明:随着热处理温度的升高,当试件局部水冷后,小孔的孔径及含量不断增大,而大孔径变化不是特别明显,试件的损伤度也相应增大;同时,经高温及局部水冷处理后,试件核磁共振成像灰度值的概率密度分布中的峰随温度的增大向右移动,且温度越高,概率密度分布函数对应的灰度值增幅越大,与T2谱的变化一致。最后,求解了水泥砂浆试件高温及局部水冷后的温度和温度应力的分布,并基于最大拉应力准则求解了200 ℃和400 ℃后局部冷却水泥砂浆试件的裂纹萌发及扩展范围。当温度为200 ℃时局部水冷所产的温度应力不足以引起试件裂纹的萌生。
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| 关 键 词： | 水泥砂浆 低场核磁共振技术 高温 局部水冷 热损伤 灰度值 裂纹扩展 |
| 收稿时间： | 2022-07-22 |
Research on Local Thermal Damage of High Temperature Cement Mortar Based on Low Field Nuclear Magnetic Resonance |
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| HAO Kun,NING Lin,GUO Hongyan,LIU Maoyi. Research on Local Thermal Damage of High Temperature Cement Mortar Based on Low Field Nuclear Magnetic Resonance[J]. Bulletin of the Chinese Ceramic Society, 2022, 41(12): 4163-4171 |
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| Authors: | HAO Kun NING Lin GUO Hongyan LIU Maoyi |
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| Affiliation: | 1. China Merchants Chongqing Communications Technology Research & Design Institute Co., Ltd., Chongqing 400067, China;2. College of Civil Engineering, Guizhou University, Guiyang 550025, China;3. Chongqing Construction Investment Group Co., Ltd., Chongqing 400023, China |
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| Abstract: | In order to study the damage evolution characteristics and crack propagation of high temperature cement mortar after local water cooling, a hole was drilled in the middle of cement mortar specimen. The specimen was heated to 200 ℃ and 400 ℃, and then water was injected into the hole for local cooling. The damage behavior of cement mortar specimen under high temperature and local water cooling was studied by low field nuclear magnetic resonance (NMR). The results show that with the increase of the heat treatment temperature, the pore size and content of the small hole of the specimen after local water cooling increase continuously, while the change of the large pore is not particularly obvious, and the damage degree of the specimen increases correspondingly. At the same time, after high temperature and local water cooling treatment, the peak of the probability density distribution of the gray value of magnetic resonance imaging specimens moves to the right with the increase of temperature. And the higher the temperature is, the greater the increase of the gray value corresponding to the probability density distribution function is, which is consistent with the change of T2 spectrum. Finally, the distribution of temperature and temperature stress of cement mortar specimens after high temperature and local water cooling were solved, and the crack germination and propagation range of locally cooled cement mortar specimens after 200 ℃ and 400 ℃ were solved based on the maximum tensile stress criterion.When the temperature is 200 ℃, the temperature stress produced by local water cooling is not enough to cause crack initiation. |
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| Keywords: | cement mortar low field nuclear magnetic resonance high temperature local water cooling thermal damage gray value crack propagation |
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