硅酸盐学报

高原大温差环境桥墩混凝土开裂机理

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董昊良 ¹^,² , 李化建 ¹^,³ , 石贺男 ¹^,² , 杨志强 ¹^,³ , 温家馨 ¹^,² , 黄法礼 ¹^,³ , 王振 ¹^,³ , 易忠来 ¹^,³

硅酸盐学报 | 严酷环境下高性能水泥混凝土耐久性专题—研究论文 2024,52(11): 3394-3407

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硅酸盐学报 |严酷环境下高性能水泥混凝土耐久性专题—研究论文 2024 , 52 (11) : 3394 -3407

高原大温差环境桥墩混凝土开裂机理

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董昊良¹^,², 李化建¹^,³, 石贺男¹^,², 杨志强¹^,³, 温家馨¹^,², 黄法礼¹^,³, 王振¹^,³, 易忠来¹^,³

作者信息

^1．中国铁道科学研究院，北京 100081

^2．中国铁道科学研究院研究生部，北京 100081

^3．中国铁道科学研究院集团有限公司，高速铁路轨道系统全国重点实验室，北京 100081

通讯作者:

李化建（1976—），男，博士，研究员。

作者简介:

董昊良（1999—），男，硕士研究生。

Cracking Mechanism of Bridge Piers Concrete Under Large Temperature Variation in Plateau Region

Haoliang DONG¹^,², Huajian LI¹^,³, Henan SHI¹^,², Zhiqiang YANG¹^,³, Jiaxin WEN¹^,², Fali HUANG¹^,³, Zhen WANG¹^,³, Zhonglai YI¹^,³

Affiliations

¹China Academy of Railway Sciences, Beijing 100081, China

²Postgraduate Department of China Academy of Railway Sciences, Beijing 100081, China

³State Key Laboratory Track Technology of High-Speed Railway, China Academy of Railway Science Corporation Limited, Beijing 100081, China

Corresponding Author:

LI Huajian (1976-), male, Ph.D., Professor. E-mail: chinasailor@163.com

DONG Haoliang (1999-), male, Master candidate. E-mail: dhlCARS@163.com

出版时间: 2024-11-20 doi: 10.14062/j.issn.0454-5648.20240288

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摘要

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高原大温差环境下昼夜温差使得桥墩混凝土结构存在开裂风险。针对这一现象，本工作建立了温度疲劳应力作用下桥墩混凝土的损伤模型，采用有限元分析方法研究了高原大温差环境桥墩混凝土的初裂时间和温度梯度分布等特征，并从温度疲劳应力演变规律、损伤发展和能量累积3个角度分析了高原大温差环境桥墩混凝土的开裂机理。结果表明：桥墩混凝土在温度疲劳应力作用下产生的裂缝呈现沿底部向上延伸的发展规律，且裂缝主要出现在向阳面；桥墩混凝土的初裂时间随着温差的增加而逐渐缩短，温差为60 ℃时桥墩的初裂时间由温差20 ℃时的970 d缩短至100 d，且随着温差的增加，桥墩混凝土累积塑性耗散能逐渐增加，其原因为单次温度循环时产生的温度疲劳应力和损伤累积速率随着温差的增加而提升。以期为高原大温差环境桥墩混凝土开裂预测和耐久性评估提供参考。

关键词

高原大温差 / 桥墩混凝土 / 开裂机理 / 有限元分析 / 初裂时间

Abstract

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Introduction

The climatic features of plateau regions include low atmospheric pressure, large temperature variation, and intense radiation, presenting numerous challenges for concrete structures in these areas during the service life. The substantial diurnal temperature fluctuations expose concrete structures to the risk of cracking over prolonged temperature cycles, particularly notable in complex facade structures like bridge piers, where cracks often intersect and spread across the surface. In the plateau with significant temperature variations, the surface cracks that occur in bridge pier concrete do not directly impact the structural load-bearing capacity. However, if surface damage is allowed to progress, this deterioration accelerates the penetration of moisture and CO₂, among other corrosive agents, into the interior of the concrete, thereby causing the durability of the concrete structure to fail.

This study focuses on typical bridge pier concrete in plateau regions with significant temperature variations, employing finite element analysis and secondary development techniques to establish a temperature fatigue damage model for bridge pier concrete under such conditions. By incorporating cohesive elements to simulate the cracking behavior of bridge pier concrete under long-term temperature cycling, this research elucidates features such as the initial crack time and temperature gradient distribution in plateau regions with significant temperature variations. Furthermore, through an analysis of the fatigue stress evolution patterns and energy accumulation processes of bridge pier concrete under temperature cycling, this study aims to uncover its cracking mechanisms.

Methods

Based on the cracking mechanism of bridge piers in the high plateau environment with significant temperature variations, this study establishes a finite element model for a dual-lane circular bridge pier. The model dimensions are 7.4 m (length) × 3.0 m (width) × 9.0 m (height). The mesh consists of hexahedral elements, with element types C3D8R and cohesive elements embedded along the mesh boundaries. The concrete material properties for the bridge pier include an elastic modulus of 42 GPa, tensile strength of 2.5 MPa, poisson's ratio of 0.2, linear expansion coefficient of 1.5×10^-5, density of 2 420 kg/m³, and specific heat capacity of 1 100 J/(kg·℃). Diurnal temperature variations are set at 20-40, 20-60 ℃, and 20-80 ℃, respectively. Additionally, considering the difference between the sunny and shaded sides of the bridge pier concrete, a temperature variation of 10 ℃ is defined for the shaded side. The bottom of the bridge pier concrete is fully constrained, while the top is subjected to an upper load of 9 000 kN. Importantly, a threshold value is introduced to determine whether fatigue effects on concrete need to be considered during alternating diurnal temperature cycles.

Results and discussion

Intense solar radiation and longer hours of sunshine in plateau regions lead to the appearance of randomly distributed cracks with widths less than 0.5 mm in bridge piers after 1-2 years of normal usage. The cracking mechanism of bridge pier concrete in plateau environments is as follows: the bridge pier concrete surface heats up to 50 ℃ due to thermal radiation and air convection. Heat is then transferred internally through a heat transfer process consistent with Fourier's law. The temperature gradients generated inside the bridge pier concrete, due to its low thermal conductivity, create temperature fatigue stresses, ultimately resulting in surface cracking under the influence of temperature fatigue stress.

Based on finite element analysis, this study demonstrates that in plateau environments with significant temperature variations, bridge pier concrete tends to initiate cracking from the bottom and gradually extend upwards. Additionally, it is shown that the alternation between day and night results in a more complex internal temperature field within the bridge pier concrete. It is noteworthy that as the diurnal temperature variation increases, the rate of damage accumulation on the surface of the bridge pier concrete gradually increases. Furthermore, the plastic dissipation energy generated in the bridge pier concrete over the same period also increases with the rise in diurnal temperature variation, thereby revealing the cracking mechanism of the bridge pier concrete.

Conclusions

This paper takes typical bridge piers in high plateau regions as an example and, through theoretical analysis, reveals the complete process of "thermal response-stress generation-fatigue damage accumulation" cracking mechanism of bridge piers in environments with significant temperature variations. Based on the cracking principles of bridge piers in such environments, a fatigue damage model under temperature fatigue is established using finite element simulation and secondary development techniques. Concurrently, cohesive elements are utilized to simulate the cracking behavior of bridge piers under prolonged temperature cycling. Subsequently, it is demonstrated that in environments with significant temperature variations, cracks in bridge piers extend upwards from the bottom according to a certain development pattern. Moreover, with the increase in temperature variation on the bridge pier surface, both the initial crack time and damage accumulation rate gradually accelerate.

Key words

plateau with large temperature variation / bridge pier concrete / cracking mechanism / finite element analysis / initial cracking time

引用本文

董昊良, 李化建, 石贺男, 杨志强, 温家馨, 黄法礼, 王振, 易忠来. 高原大温差环境桥墩混凝土开裂机理. 硅酸盐学报, 2024 , 52 (11) : 3394 -3407 . DOI: 10.14062/j.issn.0454-5648.20240288

Haoliang DONG, Huajian LI, Henan SHI, Zhiqiang YANG, Jiaxin WEN, Fali HUANG, Zhen WANG, Zhonglai YI. Cracking Mechanism of Bridge Piers Concrete Under Large Temperature Variation in Plateau Region[J]. Journal of the Chinese Ceramic Society, 2024 , 52 (11) : 3394 -3407 . DOI: 10.14062/j.issn.0454-5648.20240288

基金

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国家自然科学基金(52208299; 52108260)

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2024年第52卷第11期

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文章信息

doi: 10.14062/j.issn.0454-5648.20240288

接收时间：2024-04-19
首发时间：2026-10-22
出版时间：2024-11-20

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出版历史

收稿日期：2024-04-19
修回日期：2024-05-05

基金

国家自然科学基金(52208299; 52108260)

作者信息

^1．中国铁道科学研究院，北京 100081

^2．中国铁道科学研究院研究生部，北京 100081

^3．中国铁道科学研究院集团有限公司，高速铁路轨道系统全国重点实验室，北京 100081

通讯作者:

李化建（1976—），男，博士，研究员。

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https://castjournals.cast.org.cn/joweb/gsyxb/CN/10.14062/j.issn.0454-5648.20240288

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2种不同金属材料的力学参数

科 Family	属数 Number of genus	种数 Number of species	占总种数比例 Percentage of total species (%)	属 Genus	种数 Number of species	占总种数比例 Percentage of total species (%)
鹅膏菌科Amanitaceae	2	11	5.26	鹅膏菌属 Amanita	10	4.78
小菇科 Mycenaceae	2	12	5.74	丝盖伞属 Inocybe	5	2.39
多孔菌科 Polyporaceae	8	14	6.70	蜡蘑属 Laccaria	5	2.39
红菇科 Russulaceae	3	23	11.00	小皮伞属 Marasmius	6	2.87
				小菇属 Mycena	11	5.26
				光柄菇属 Pluteus	5	2.39
				红菇属 Russula	17	8.13
				栓菌属 Trametes	5	2.39

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