混凝土界面过渡区对裂纹扩展过程的影响

贾世旭; 赵婷婷; 吴佩; 李志强; 王志勇

doi:10.11858/gywlxb.20230606

混凝土界面过渡区对裂纹扩展过程的影响

doi: 10.11858/gywlxb.20230606

贾世旭^1,,
赵婷婷^{1, 2, 3, 4,*, ,},
吴佩⁵,
李志强^{1, 4},
王志勇^{1, 4}

1.
太原理工大学机械与运载工程学院，山西太原　030024
2.
北京理工大学爆炸科学与技术国家重点实验室，北京　100081
3.
宁波大学冲击与安全工程教育部重点实验室，浙江宁波　315211
4.
太原理工大学山西省材料强度与结构冲击重点实验室，山西太原　030024
5.
湖北省水利水电规划勘测设计院，湖北武汉　430070

基金项目: 国家自然科学基金（12102294，12072217）；山西省回国留学人员科研资助项目（2022-067）；山西省基础研究计划青年科学研究项目（2021032124158）；爆炸科学与技术国家重点实验室（北京理工大学）开放基金（KFJJ22-14M）；宁波大学冲击与安全工程教育部重点实验室开放基金（CJ20202109）

详细信息

作者简介:
贾世旭（1997－），男，硕士研究生，主要从事混凝土离散元建模研究. E-mail：jiashixu2022@163.com

通讯作者:
赵婷婷（1989－），女，博士，副教授，主要从事离散元算法研究. E-mail：zhaotingting@tyut.edu.cn

中图分类号: O346.1; TU528
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出版历程
- 收稿日期: 2023-02-01
- 修回日期: 2023-03-17
- 录用日期: 2023-03-30
- 刊出日期: 2023-09-01

Influence of Interfacial Transition Zone on Crack Propagation Process in Concrete

JIA Shixu^1
,,
ZHAO Tingting^{1, 2, 3, 4,*
, ,},
WU Pei⁵,
LI Zhiqiang^{1, 4},
WANG Zhiyong^{1, 4}

1.
College of Mechanical and Vehicle Engineering, Taiyuan University of Technology, Taiyuan 030024, Shanxi, China
2.
State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081, China
3.
Key Laboratory of Impact and Safety Engineering, Ministry of Education,Ningbo University, Ningbo 315211, Zhejiang, China
4.
Shanxi Key Laboratory of Material Strength and Structural Impact, Taiyuan University of Technology, Taiyuan 030024, Shanxi, China
5.
Hubei Institute of Water Resources Survey and Design, Wuhan 430070, Hubei, China

摘要

摘要: 混凝土是由水泥砂浆、粗骨料和界面过渡区（interfacial transition zone, ITZ）组成的非均质复合材料。ITZ作为混凝土内部的最薄弱相，对混凝土的宏观断裂有重要影响。基于PFC 2D的FISH语言，建立了能反映混凝土骨料、水泥砂浆和ITZ等复杂细观结构的离散元模型，并探讨了在单轴压缩载荷下ITZ强度分布和强度值对混凝土裂纹扩展过程的影响。数值模拟结果表明：混凝土裂纹遵循从中心向加载端扩展的趋势，超过80%的裂纹出现在峰值应力后的软化阶段；ITZ强度分布对混凝土裂纹扩展过程影响较弱，当ITZ强度呈现U形分布时，混凝土中裂纹数量较多；ITZ强度值对混凝土断裂程度及最终断裂形式影响显著，当ITZ的最小黏结强度与砂浆黏结强度比p<0.5时，混凝土强度显著降低，且裂纹围绕混凝土模型中心分散扩展形成网状宏观裂纹，导致试件发生散碎破坏，当p>0.6时，裂纹从混凝土试样中心向加载端集中扩展形成宏观贯通裂纹，导致试件发生块状破坏。
- 混凝土 /
- 界面过渡区 /
- 离散元法 /
- 细观模型 /
- 裂纹扩展
Abstract: Concrete is a heterogeneous composite material composed of coarse aggregate, mortar and interfacial transition zone (ITZ). ITZ is the weakest phase inside the concrete and has a significant effect on the macroscopic fracture process of concrete. To respectively explore the effects of the distribution and value of ITZ strength on the crack propagation process in concrete under uniaxial compression, a discrete element model that reflects complex mesostructures of concrete aggregate, mortar and ITZ is established in PFC 2D by the use of FISH code. The numerical simulation results showed that cracks follow the propagation order from the centre of concrete to the loading end during the crack propagation process, and more than 80% of cracks appear in the softening stage after peak stress. The ITZ strength distribution has a weak effect on the crack propagation process in concrete, and the number of cracks in concrete is large when the ITZ strength shows a U shape distribution. The decrease in ITZ strength value leads to a gradual increase in the number and range of cracks. When the ratio of the minimum bond strength of ITZ to the bond strength of mortar p<0.5, the concrete strength is significantly reduced and the cracks expand around the centre of the concrete model to form a network macro-crack, resulting in scattered fracture failure. When p>0.6, the cracks expand from the centre of the concrete specimen to the loading end to form a macroscopic penetration crack, resulting in block fracture failure.
- concrete /
- interfacial transition zone /
- discrete element method /
- mesoscale model /
- crack propagation

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图 1 随机骨料的分布

Figure 1. Distribution of random aggregates

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图 2 ITZ细观结构示意图

Figure 2. Schematic diagram of ITZ meso structure

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图 3 3种ITZ强度分布方式

Figure 3. Three strength distribution modes of ITZ

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图 4 PFC单轴压缩混凝土的数值模型

Figure 4. Numerical model of concrete under uniaxial compression in PFC

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图 5 平行黏结模型的基本结构

Figure 5. Basic structure of parallel bond model

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图 6 单轴压缩实验^[19]与数值模拟的应力-应变曲线对比

Figure 6. Comparison of stress-strain curves between uniaxial compression experimental^[19] and numerical results

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图 7 破坏块体和裂纹分布的数值模拟结果

Figure 7. Numerical simulation results of fragments and crack distribution

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图 8 不同ITZ强度分布下的应力-应变曲线对比

Figure 8. Comparison among stress-strain curves for different ITZ strength distributions

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图 9 不同ITZ强度分布下的裂纹数量

Figure 9. Comparison among the number of cracks for different ITZ strength distributions

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图 10 不同ITZ强度分布下的裂纹形态

Figure 10. Crack propagation morphology for different ITZ strength distributions

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图 11 不同ITZ强度值下的应力-应变曲线

Figure 11. Stress-strain curves for different ITZ strength values

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图 12 不同ITZ强度值下的裂纹数量对比

Figure 12. Comparison among the number of cracks for different ITZ strength values

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图 13 不同ITZ强度值下的裂纹形态

Figure 13. Crack propagation morphology for different ITZ strength values

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表 1 不同ITZ强度分布下ITZ与砂浆的强度比

Table 1. Strength ratio of ITZ to mortar for different ITZ strength distributions

Distribution mode	ITZ layer	σ_ITZ/σ_mortar	Distribution mode	ITZ layer	σ_ITZ/σ_mortar
Incremental distribution	ITZ 1	0.80	Average distribution	ITZ 1	0.80
	ITZ 2	0.86		ITZ 2	0.80
	ITZ 3	0.90		ITZ 3	0.80
	ITZ 4	0.94		ITZ 4	0.80
	ITZ 5	0.98		ITZ 5	0.80
U shape distribution	ITZ 1	0.90
	ITZ 2	0.85
	ITZ 3	0.80
	ITZ 4	0.90
	ITZ 5	0.98

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表 2 5组模型中ITZ与砂浆的强度比

Table 2. Strength ratio of ITZ to mortar for 5 groups of models

Model	p	ITZ layer	σ_ITZ/σ_mortar
1	0.40	ITZ 1	0.40
		ITZ 2	0.65
		ITZ 3	0.80
		ITZ 4	0.90
		ITZ 5	0.98
2	0.50	ITZ 1	0.50
		ITZ 2	0.70
		ITZ 3	0.83
		ITZ 4	0.91
		ITZ 5	0.98
3	0.60	ITZ 1	0.60
		ITZ 2	0.75
		ITZ 3	0.85
		ITZ 4	0.92
		ITZ 5	0.98
4	0.70	ITZ 1	0.70
		ITZ 2	0.80
		ITZ 3	0.88
		ITZ 4	0.93
		ITZ 5	0.98
5	0.80	ITZ 1	0.80
		ITZ 2	0.86
		ITZ 3	0.90
		ITZ 4	0.94
		ITZ 5	0.98

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表 3 接触细观参数

Table 3. Meso-parameters of contacts

Material	E_c/GPa	k^*	μ	λ	σ_t/MPa	C/MPa	φ/(°)
Aggregate	100	1.5	0.3	1	1000	1000	45
Mortar	10	1.5	0.3	1	20	20	45

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