Study on microcracks propagation characteristics of granite under high temperature

doi:10.14088/j.cnki.issn0439-8114.2022.06.029

Abstract

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

CLC Number:

TU458

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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