| 摘要: |
| 针对全混凝土液化天然气储罐面临的超低温冻融循环问题，自主设计了一种高强耐低温混凝土（LHC）；对不同超低温冻融循环次数下LHC和C60混凝土进行了单轴和三轴压缩试验.结果表明：LHC和C60混凝土强度均随循环次数增加而降低，且相同超低温冻融循环次数下，LHC的强度均高于C60混凝土；利用Weibull分布，以弹性模量作为损伤变量，得出了单轴和三轴应力状态下损伤演化速度和最终损伤度随超低温冻融循环次数的变化规律；通过压汞（MIP）和核磁共振（NMR）试验，分析了不同状态下LHC和C60混凝土孔隙特性的变化规律，证明了孔隙水是影响混凝土抗超低温冻融循环能力的重要因素，并从微观上解释了LHC具有更好抗超低温冻融循环能力的机理. |
| 关键词: 液化天然气储罐 超低温冻融循环 损伤演化 压汞 核磁共振 |
| DOI：10.3969/j.issn.1007-9629.2022.05.008 |
| 分类号:TU528.01 |
| 基金项目:“十三五”国家重点研发计划资助项目（2016YFC0600803） |
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| Damage Evolution Law and Mechanism of Concrete under Cryogenic Freeze-Thaw Cycles |
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ZHOU Dawei1, LIU Juanhong1,2,3, DUAN Pinjia4, CHENG Linian1, LOU Baichuan1
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1.School of Civil and Resource Engineering， University of Science and Technology Beijing， Beijing 100083， China;2.Beijing Key Laboratory of Urban Underground Space Engineering， University of Science and Technology Beijing， Beijing 100083， China;3.State Key Laboratory of High-Efficient Mining and Safety of Metal Mines， Ministry of Education， University of Science and Technology Beijing， Beijing 100083， China;4.China National Offshore Oil and Gas Group Co.， Ltd.， Beijing 100028， China
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| Abstract: |
| To solve the cryogenic freeze-thaw cycles problem faced by all-concrete liquefied natural gas storage tanks， a low temperature resistant and high strength concrete （LHC） was designed. By the uniaxial and triaxial compressive strength tests of LHC and C60 concrete under different cryogenic freeze-thaw cycles， it is concluded that the strength of LHC and C60 concrete decreases as the number of cycles increases. Under the same number of cryogenic freeze-thaw cycles， the strength of LHC is higher than that of ordinary C60 concrete. By using the Weibull distribution and taking the elastic modulus as the damage variable， the damage evolution rate and final damage degree with the number of cryogenic freeze-thaw cycles are obtained. Through mercury intrusion porosimetry（MIP） and nuclear magnetic resonance （NMR） tests， the pore characteristics of LHC and C60 concrete under different conditions are analyzed， which indicated that pore water is an important factor affecting the ability of concrete to resist cryogenic freeze-thaw cycles. The reason why LHC has better resistance to cryogenic freeze-thaw cycles is explained from the microscopic perspective. |
| Key words: liquefied natural gas storage tank cryogenic freeze-thaw cycle damage evolution MIP NMR |
