Mechanical behaviors and fracture characteristics of heat-treated sandstone with pre-existing flaw under uniaxial compression: A study on the failure behavior of flawed building sandstone after fire

IF 5.6 2区工程技术 Q1 ENGINEERING, MECHANICAL

Theoretical and Applied Fracture Mechanics Pub Date : 2025-09-10 DOI:10.1016/j.tafmec.2025.105231

Weijing Xiao , Kun Liu , Dongming Zhang , Haosen Guo , Shujian Li , Hongpeng Wan

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Abstract

In civil engineering, building sandstone often develops defects due to weathering and crustal movement. Investigating the failure mechanisms of such defective rocks under elevated temperatures is therefore essential for postfire restoration and stability analysis of buildings. In this paper, uniaxial compression experiments are conducted on the flawed sandstone exposed to temperatures ranging from 25 °C to 1000 °C. The stress–strain curves, acoustic emission (AE) signals and macroscopic fracture images of rock are obtained. The rock mechanical properties and fracture characteristics are analyzed. The results show that: (1) the strength of the sandstone is the highest at 200 °C, and the peak strength decreases with temperature rise after 200 °C, and the energy dissipation becomes more significant. (2) the failure starts from the wing crack at the flaw tips, and then gradually cross through to form a macroscopic fracture surface. The complexity of rock fracture cracks increases exposed to temperatures more than 400 °C, and the fluctuation of AE correlation dimension reflects the nonlinear evolution process of rock internal damage. (3) When the temperature is lower than 400 °C, the proportion of shear cracks exceeds that of tension cracks only when the stress level exceeds 80 %. When the temperature reaches 800 °C, the proportion of shear cracks always exceeds that of tension cracks, and the progressive failure is particularly obvious, which is related to rock thermal fracture and the loose rock particles after high temperatures. The research results provide reference for post-disaster restoration and stability analysis of rock buildings after fire.

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含缺陷热处理砂岩单轴压缩力学行为及断裂特征——含缺陷建筑砂岩火灾后破坏行为研究

在土木工程中，建筑砂岩常因风化和地壳运动而产生缺陷。因此，研究高温下缺陷岩的破坏机制对火灾后建筑物的修复和稳定性分析至关重要。本文对暴露在25℃~ 1000℃温度下的有缺陷砂岩进行了单轴压缩实验。得到了岩石的应力-应变曲线、声发射信号和宏观断裂图像。分析了岩石的力学特性和断裂特征。结果表明：(1)砂岩在200℃时强度最高，200℃后峰值强度随温度升高而降低，能量耗散更加显著；(2)破坏从裂纹尖端的翼状裂纹开始，然后逐渐穿过，形成宏观断裂面。当温度超过400℃时，岩石断裂裂纹的复杂性增加，声发射相关维数的波动反映了岩石内部损伤的非线性演化过程。(3)当温度低于400℃时，只有当应力水平超过80%时，剪切裂缝的比例才会超过拉裂缝的比例。当温度达到800℃时，剪切裂缝的比例始终超过拉伸裂缝，且渐进性破坏尤为明显，这与岩石热破裂和高温后岩石颗粒疏松有关。研究结果可为火灾后岩石建筑的灾后修复和稳定性分析提供参考。

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来源期刊

Theoretical and Applied Fracture Mechanics 工程技术-工程：机械

CiteScore

8.40

自引率

18.90%

发文量

435

审稿时长

37 days

期刊介绍： Theoretical and Applied Fracture Mechanics'' aims & scopes have been re-designed to cover both the theoretical, applied, and numerical aspects associated with those cracking related phenomena taking place, at a micro-, meso-, and macroscopic level, in materials/components/structures of any kind. The journal aims to cover the cracking/mechanical behaviour of materials/components/structures in those situations involving both time-independent and time-dependent system of external forces/moments (such as, for instance, quasi-static, impulsive, impact, blasting, creep, contact, and fatigue loading). Since, under the above circumstances, the mechanical behaviour of cracked materials/components/structures is also affected by the environmental conditions, the journal would consider also those theoretical/experimental research works investigating the effect of external variables such as, for instance, the effect of corrosive environments as well as of high/low-temperature.