Scaling of the fracture process zone in rock

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• 作者：Ali Tarokh ; Roman Y. Makhnenko ; Ali Fakhimi…
• 关键词：Fracture process zone ; Size effect ; Brittleness number ; Acoustic emission ; Discrete element method
• 刊名：International Journal of Fracture
• 出版年：2017
• 出版时间：April 2017
• 年：2017
• 卷：204
• 期：2
• 页码：191-204
• 全文大小：
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Characterization and Evaluation of Materials; Classical Mechanics; Civil Engineering; Automotive Engineering; Mechanical Engineering;
• 出版者：Springer Netherlands
• ISSN：1573-2673
• 卷排序：204

文摘

The zone of microcracks surrounding a notch tip—the process zone—is a phenomenon observed in fracture of quasi-brittle materials, and the characterization of the process zone is the topic of the paper. Specimens of different sizes with a center notch fabricated from a granite of large grain (Rockville granite, average grain size of 10 mm), were tested in three-point bending. Acoustic emissions were recorded and locations of microcracks were determined up to peak load. The results show that both the length and width of the process zone increase with the increase of the specimen size. Furthermore, the suitability of a proposed theoretical relationship between the length and width of the process zone and specimen size was studied experimentally and numerically. The discrete element method with a tension softening contact bond model was used to investigate the development of the process zone with the specimen size. A synthetic rock composed of rigid circular particles that interact through normal and shear springs was tested in the numerical simulations. It was shown that the limiting specimen size, beyond which no further noticeable increase in the length of the process zone is observed, is significantly larger than the limiting specimen size beyond which the width of the process zone shows no size effect.