超高性能混凝土劈拉损伤破坏的声光联合表征
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作者单位:

1.河海大学 土木与交通学院;2.苏交科集团股份有限公司;3.中建三局集团有限公司

基金项目:

国家重点研发计划(2021YFB2600200);国家自然科学(51979090, 52379124)


Acousto-optic characterization of splitting tensile damage of ultra-high per-formance concrete
Affiliation:

1.Hohai University;2.Jsti Group;3.China Construction Third Engineering Group Co., Ltd

Fund Project:

The National Key Technologies R&D Program of China,National Natural Science Foundation of China

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    摘要:

    为研究UHPC(Ultra-High Performance Concrete)的劈拉破坏特征,采取3种不同的加载速率(0.1 mm/s、0.01 mm/s、0.001 mm/s)进行劈拉加载。在加载过程中,采用数字图像相关(Digital Image Correlation,DIC)方法进行非接触式观测裂缝演化,同时结合声发射(Acoustic emission,AE)技术对UHPC的破坏全过程进行动态监测,并基于DIC应变云图、AE参量分析试件的破坏特征。结果表明,由于有钢纤维的掺入,改善了混凝土的脆性,UHPC峰后荷载-位移曲线下降得更平缓,不会出现急剧下降的情况。加载速率越高,UHPC测出劈拉强度越高,符合混凝土速率效应规律,加载速率由0.001 mm/s提升到0.01 mm/s和由0.01 mm/s提升到0.1 mm/s,劈拉峰值荷载分别提高27.9%,28.5%。采用数字图像相关法进行UHPC劈拉试验的变形测量,可获得连续的变形数据,能完整地捕捉裂缝的开展过程,证明DIC能很好地反映试件表面裂缝开展演化过程。基于RA-AF的断裂模式分析可以快捷、有效判混凝土中的裂缝开展类型。根据分析结果,UHPC劈拉试验的裂缝类型绝大多数为拉伸裂缝,同时随着加载速率的提高,拉伸裂缝占总裂缝的比例提高。

    Abstract:

    In order to study the splitting tensile failure characteristics of UHPC (Ultra-High Performance Concrete), three different loading rates (0.1 mm/s, 0.01 mm/s, 0.001 mm/s) were used for splitting tensile loading. During the loading process, the digital image correlation (DIC) method was used to observe the crack evolution by non-contact deformation. At the same time, the acoustic emission (AE) technology was used to dynamically monitor the whole failure process of UHPC, and the failure characteristics of the specimen were analyzed based on the DIC strain cloud map and AE parameters. The results show that due to the incorporation of steel fibers, the brittleness of concrete is improved, and the post-peak load-displacement curve of UHPC decreases more gently without a sharp decline. The higher the loading rate, the higher the splitting tensile strength measured by UHPC, which conforms to the law of concrete rate effect. When the loading rate is increased from 0.001 mm/s to 0.01 mm/s and from 0.01 mm/s to 0.1 mm/s, the splitting tensile peak load is increased by 27.9 % and 28.5 % respectively. The digital image correlation method is used to measure the deformation of UHPC splitting tensile experiment, and continuous deformation data can be obtained, which can completely capture the development process of cracks. It is proved that DIC can well reflect the evolution process of cracks on the surface of specimens. The fracture mode analysis based on RA-AF can quickly and effectively determine the type of crack development in concrete. According to the analysis results, the crack types of UHPC splitting tensile experiment are mostly tensile cracks, and the proportion of tensile cracks in the total cracks increases with the increase of loading rate.

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  • 收稿日期:2023-09-23
  • 最后修改日期:2023-11-04
  • 录用日期:2023-11-20
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