冻融循环后蒸养混凝土损伤-声发射特性研究
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1.河海大学;2.扬州大学

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国家自然科学基金面上项目(52079049), 国家自然科学基金重点项目(51739003)


Study on the damage-acoustic emission characteristics of steam-cured concrete after freeze-thaw cycles
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1.Hohai University;2.Yangzhou University

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    摘要:

    为研究冻融对蒸养混凝土力学性能演化规律的影响,通过开展蒸养混凝土试件冻融循环试验和单轴压缩-声发射试验,分析了冻融循环作用后,不同蒸养制度混凝土的力学特性和加载损伤破坏声发射过程,依据声发射特征参数建立了冻融条件下蒸养混凝土损伤本构模型,探究了损伤变量与冻融循环作用次数的变化关系。研究表明:60℃和80℃蒸养温度对混凝土抗冻性能不利,40℃蒸养混凝土与标准养护混凝土抗冻性能无明显差异;混凝土受压破坏过程的声发射振铃计数变化呈现出明显的接触期、平静期、陡增期三阶段变化规律,平静期-陡增期分界点随冻融循环次数的增加在时间上发生后移;受压过程前期,蒸养混凝土损伤发展较为缓慢;相对峰值应力达0.8以后,蒸养混凝土损伤发展较为迅速,直至受压破坏。

    Abstract:

    To study the influence of freeze-thaw on the evolution of steam-cured concrete mechanical properties. In response to this problem, the freeze-thaw cycle test and uniaxial compression-acoustic emission test of steam-cured concrete specimens were carried out to analyze the damage characteristics of concrete under different steam-curing systems under the action of freeze-thaw cycles. According to the characteristic parameters of acoustic emission, a constitutive model of steam-cured concrete damage was established under freeze-thaw conditions, and the relationship between damage variables and the number of freeze-thaw cycles was discussed. The results show that the 60℃ and 80℃ steam curing temperature is not good for the frost resistance of concrete, and there is no significant difference between 40℃ steam-cured concrete and standard-cured concrete in frost resistance. The change of the acoustic emission ringing count in the process of concrete compression failure shows obvious three-stage changes in contact period, quiet period and spike period. The demarcation point between the quiet period and the spike period shifts back in time with the increase in the number of freeze-thaw cycles. In the early stage of the compression process, the damage of steam-cured concrete develops slowly; when the relative peak stress reaches 0.8, the damage of steam-cured concrete develops more rapidly until it fails under compression.

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  • 收稿日期:2021-12-05
  • 最后修改日期:2022-05-06
  • 录用日期:2022-05-06
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