{"title":"Compression-shear failure of thermally treated granite: insights from digital image correlation analysis","authors":"","doi":"10.1016/j.geothermics.2024.103157","DOIUrl":null,"url":null,"abstract":"<div><p>Understanding the temperature-dependent shear failure behavior of rock under compression-shear loads is significant for evaluating the stability of deep surrounding rock with high temperature. In this study, a series of variable angle shear (VAS) tests, were conducted on cubic granite specimens exposed to different high temperatures, observed by two-dimensional digital image correlation (2D-DIC) technique during the tests. The results show that the peak shear stress, the peak shear strain and shear modulus decrease with the shear angle <em>α</em>, regardless of the treatment temperature. The peak shear stress increases slightly as the high temperature rises to 400 °C, then decrease rapidly. Both the peak shear strain and shear modulus do not change significantly until 400 °C and 500 °C respectively, then reduce rapidly. The cohesion reduces and the internal friction angle increases with increasing temperature. Based on the principal strain field, the damage evolution and crack extension processes of typical specimen are analyzed. It shows that the cracks initiate from the upper and lower loading points, which further coalesce with each other at the middle part of shear band. The shear angle <em>α</em> has a significant effect on the compression-shear failure behavior of granite. The tension failures become less visible with increase of <em>α</em> and dominant failure patterns transform from mixed tension-shear failure to shear failure. The ratio of crack initiation force to peak load reduces obviously at 600 °C. In addition, the underlying failure mechanism of specimens under compression-shear load is explained by an established mechanical model in the paper.</p></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":null,"pages":null},"PeriodicalIF":3.5000,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Geothermics","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0375650524002438","RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"ENERGY & FUELS","Score":null,"Total":0}
引用次数: 0
Abstract
Understanding the temperature-dependent shear failure behavior of rock under compression-shear loads is significant for evaluating the stability of deep surrounding rock with high temperature. In this study, a series of variable angle shear (VAS) tests, were conducted on cubic granite specimens exposed to different high temperatures, observed by two-dimensional digital image correlation (2D-DIC) technique during the tests. The results show that the peak shear stress, the peak shear strain and shear modulus decrease with the shear angle α, regardless of the treatment temperature. The peak shear stress increases slightly as the high temperature rises to 400 °C, then decrease rapidly. Both the peak shear strain and shear modulus do not change significantly until 400 °C and 500 °C respectively, then reduce rapidly. The cohesion reduces and the internal friction angle increases with increasing temperature. Based on the principal strain field, the damage evolution and crack extension processes of typical specimen are analyzed. It shows that the cracks initiate from the upper and lower loading points, which further coalesce with each other at the middle part of shear band. The shear angle α has a significant effect on the compression-shear failure behavior of granite. The tension failures become less visible with increase of α and dominant failure patterns transform from mixed tension-shear failure to shear failure. The ratio of crack initiation force to peak load reduces obviously at 600 °C. In addition, the underlying failure mechanism of specimens under compression-shear load is explained by an established mechanical model in the paper.
了解岩石在压缩-剪切载荷作用下随温度变化的剪切破坏行为,对于评估深层围岩在高温下的稳定性具有重要意义。本研究对暴露在不同高温下的立方体花岗岩试样进行了一系列变角剪切(VAS)试验,并在试验过程中采用二维数字图像相关(2D-DIC)技术进行了观察。结果表明,无论处理温度如何,峰值剪切应力、峰值剪切应变和剪切模量都随剪切角 α 的增大而减小。当高温升至 400 °C 时,峰值剪切应力略有增加,然后迅速减小。峰值剪切应变和剪切模量分别在 400 °C 和 500 °C 之前变化不大,然后迅速减小。内聚力随温度升高而减小,内摩擦角随温度升高而增大。根据主应变场,分析了典型试样的损伤演变和裂纹扩展过程。结果表明,裂纹从上部和下部的加载点开始,在剪切带的中间部分进一步相互凝聚。剪切角 α 对花岗岩的压缩-剪切破坏行为有显著影响。随着α的增大,拉伸破坏变得不明显,主要破坏模式从拉伸-剪切混合破坏转变为剪切破坏。600 °C时,裂纹起始力与峰值载荷之比明显降低。此外,本文还通过一个已建立的力学模型解释了试样在压缩-剪切载荷作用下的基本破坏机理。
期刊介绍:
Geothermics is an international journal devoted to the research and development of geothermal energy. The International Board of Editors of Geothermics, which comprises specialists in the various aspects of geothermal resources, exploration and development, guarantees the balanced, comprehensive view of scientific and technological developments in this promising energy field.
It promulgates the state of the art and science of geothermal energy, its exploration and exploitation through a regular exchange of information from all parts of the world. The journal publishes articles dealing with the theory, exploration techniques and all aspects of the utilization of geothermal resources. Geothermics serves as the scientific house, or exchange medium, through which the growing community of geothermal specialists can provide and receive information.