Effects of Rock Specimen Size on Mechanical Properties in Laboratory Testing
Publication: Journal of Geotechnical and Geoenvironmental Engineering
Volume 147, Issue 5
Abstract
The design of rock engineering projects requires an estimation of the strength of intact rock blocks. These blocks can be significantly larger than the typical laboratory test specimen; thus, understanding the specimen size effect on mechanical properties is essential. In this paper, a series of uniaxial compression tests and Brazilian disc tests were conducted on cylindrical samples with diameters varying from 20 to 150 mm, and direct shear tests were conducted on cubic samples with side lengths varying from 50 to 200 mm. The results showed that the uniaxial compressive strength (UCS), cohesion, and Young’s modulus decrease with increasing specimen size, whereas the tensile strength initially increases and then decreases. Moreover, the applicability of different size effect models to experimental data was assessed. It was concluded that the fitting equations of UCS and cohesion are almost the same, whereas that of tensile strength is significantly different. The size effect law of rock mechanics parameters may be affected by the failure mode.
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Data Availability Statement
All data, models, and code generated or used during the study appear in the article.
Acknowledgments
The research work presented in this paper is in part supported by the Fundamental Research Funds for the Central Universities (Grant No. 2042019kf0029) and Hubei Provincial Natural Science Foundation of China (Grant No. 2019CFB317). The authors are grateful for the financial support.
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Journal of Geotechnical and Geoenvironmental Engineering
Volume 147 • Issue 5 • May 2021
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© 2021 American Society of Civil Engineers.
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Received: Jan 5, 2020
Accepted: Oct 28, 2020
Published online: Feb 18, 2021
Published in print: May 1, 2021
Discussion open until: Jul 18, 2021
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