高温作用下花岗岩的微裂纹衍生特性研究

doi:10.14088/j.cnki.issn0439-8114.2022.06.029

摘要/Abstract

摘要： 为研究花岗岩的高温破坏性质,利用电子显微镜观察花岗岩样品的矿物组成和微观结构,通过搭载于光学显微镜上的超高温加热台原位实时观测了花岗岩在室温20~900 ℃梯度升温过程中受温度、矿物组成影响下的热致裂纹的衍生、扩展过程,以揭示花岗岩在高温作用下力学性质下降机理。结果表明,①花岗岩材料的热致裂纹主要在加热过程中产生。②花岗岩中矿物的几何边界为主要薄弱面,热致裂纹沿矿物边界大量衍生,材料的非均质性,包括矿物组成和微观结构,对花岗岩在高温作用下劣化的影响很大。③低于500 ℃时,花岗岩仅有少量微裂纹产生;在500~600 ℃时,花岗岩破碎过程明显加剧,花岗岩裂缝网络大量产生,继续升高温度,裂缝生长速度明显减缓,裂缝网络的形成是花岗岩在500~600 ℃时宏观力学性能显著下降的主要原因。

关键词: 花岗岩, 高温, 裂纹衍生, 非均质性, 微观结构

Abstract: In order to investigate the high-temperature failure mechanism of granite, the mineral composition and microstructure of granite samples were observed by electron microscope, and the ultra-high-temperature heating instrument equipped on the optical microscope has been developed. The initiation and propagation of thermally induced cracks in granite under the influence of temperature and mineral composition during the gradient temperature rise from 20 to 900 ℃ were observed in-situ, so as to reveal the mechanism of mechanical properties decline of granite. The results showed that the thermally induced cracks of granite were mainly generated during the heating process. The geometric boundary of the mineral was the main weak surface where the microcracks were generated and expanded. At high temperature, the microcracks were generated and continuously expanded along the mineral boundary. Therefore, the heterogeneity of granite materials, including mineral composition and microstructure, had great influence on the mechanical properties under high temperature. Before 500 ℃, a few microcracks were appeared in granite. During 500~600 ℃, the fracture process of granite was obviously intensified, and the granite fracture networks were produced. With the increase of temperature, the crack growth rate was significantly slowed down. The formation of fracture network was the main reason for the significant decline of macroscopic mechanical properties of granite between 500 and 600 ℃.

Key words: granite, high temperature, cracks propagation, heterogeneit, microstructure

中图分类号:

TU458

冯雪伟. 高温作用下花岗岩的微裂纹衍生特性研究[J]. 湖北农业科学, 2022, 61(6): 148-152.

FENG Xue-wei. Study on microcracks propagation characteristics of granite under high temperature[J]. HUBEI AGRICULTURAL SCIENCES, 2022, 61(6): 148-152.

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