Bedding Plane Angles and a Horizontal Prefabricated Flaw Affecting the Cracking Characteristics of Shale Specimens
Publication: International Journal of Geomechanics
Volume 22, Issue 5
Abstract
Understanding the cracking characteristics of shale is significant for tunnel engineering and exploitation of oil and gas in shale. Unconfined compression tests were conducted on prismatic shale specimens with a horizontal prefabricated flaw. The angle between the bedding plane and the vertical compression direction changes from 0° to 90° at an interval of 30°. A high-speed camera was used to capture the cracking behavior, and the moment tensor inversion method of acoustic emission waveform was adopted for the source location and evaluation of the microfailure mechanism. The cracks compete to initiate due to stress-state dynamic redistribution, which determines the cracking behavior. The different bedding plane angles and prefabricated flaws significantly influence the cracking characteristics of shale specimens in unconfined compression tests. Five cracking modes and four main failure mechanisms were observed. The bedding planes greatly reduce shear cracks when their direction approaches the loading direction. This study provides a further understanding of the failure modes and mechanisms of shale specimens, which provides some references for projects involving shale.
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Acknowledgments
The authors acknowledge the financial support of the project (51008319 and 51779021) supported by the National Natural Science Foundation of China, the open project (LNTCCMA-20200103) from Key Laboratory of New Technology for Construction of Cities in Mountain Area, and the open fund project (LQYTKFJJ2020002) from Chongqing Key Laboratory of Geomechanics & Geoenvironment Protection.
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Published In
International Journal of Geomechanics
Volume 22 • Issue 5 • May 2022
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© 2022 American Society of Civil Engineers.
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Received: Aug 27, 2020
Accepted: Dec 15, 2021
Published online: Mar 3, 2022
Published in print: May 1, 2022
Discussion open until: Aug 3, 2022
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