Influence of grain size on strength of polymineralic crystalline rock : new insights from DEM grain-based modeling

Grain size effect on rock strength is a topic of great interest in geotechnical engineering. A consensus obtained from earlier laboratory tests is that rock strength generally decreases with the increase of grain size for both silicate and carbonate rocks; however, some recent numerical results conf...

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Main Authors: Peng, Jun, Wong, Louis Ngai Yuen, Teh, Cee Ing
Other Authors: School of Civil and Environmental Engineering
Format: Article
Language:English
Published: 2021
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Online Access:https://hdl.handle.net/10356/153533
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Institution: Nanyang Technological University
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spelling sg-ntu-dr.10356-1535332021-12-06T12:55:39Z Influence of grain size on strength of polymineralic crystalline rock : new insights from DEM grain-based modeling Peng, Jun Wong, Louis Ngai Yuen Teh, Cee Ing School of Civil and Environmental Engineering Engineering::Civil engineering Grain Size Rock Strength Grain size effect on rock strength is a topic of great interest in geotechnical engineering. A consensus obtained from earlier laboratory tests is that rock strength generally decreases with the increase of grain size for both silicate and carbonate rocks; however, some recent numerical results conflict with such laboratory test results. To address this intriguing issue, the effect of grain size on strength of polymineralic crystalline rock with low porosity is investigated numerically using the grain-based modeling (GBM) approach in discrete element method (DEM) by interpreting micro-cracking process in response to loading. In agreement with some previous DEM simulation results, the simulated rock strength is found to increase with increasing grain size for both homogeneous and heterogeneous models, even when the number of assembled disks in one mineral grain changes. The mechanism of strength increase with increasing grain size is mainly associated with the number of assembled smooth-joint contacts along grain interfaces and the generation of grain boundary cracks in response to loading. The grain interfaces significantly weaken the integrity of the rock model, which is similar to effects of inherent defects in real rock. As the grain size increases, fewer grain interfaces are built in the model and the rock strength becomes much higher. Hence, by solely changing the mineral grain size in a model, the mechanism of grain size effect as observed in laboratory tests cannot be replicated. To address this issue, a method of degradation of grain boundary strength parameters is used to mimic the possible mechanism of grain size effect. The simulated strength using the method becomes comparable with those obtained from laboratory tests when the heterogeneity in the rock is considered. Degradation of grain boundary parameters with increasing grain size provides a plausible explanation for the grain size effect on rock strength. Published version The research presented in this paper is in part supported by theNational Natural Science Foundation of China (Grant Nos. 41877217and 51609178), the General Research Fund of the Research GrantsCouncil (Hong Kong, China) (Grant No. 17303917), and theSingapore Academic Research Fund Tier 1 Grant (RG112/14) 2021-12-06T12:55:37Z 2021-12-06T12:55:37Z 2021 Journal Article Peng, J., Wong, L. N. Y. & Teh, C. I. (2021). Influence of grain size on strength of polymineralic crystalline rock : new insights from DEM grain-based modeling. Journal of Rock Mechanics and Geotechnical Engineering, 13(4), 755-766. https://dx.doi.org/10.1016/j.jrmge.2021.01.011 1674-7755 https://hdl.handle.net/10356/153533 10.1016/j.jrmge.2021.01.011 2-s2.0-85106233760 4 13 755 766 en RG112/14 Journal of Rock Mechanics and Geotechnical Engineering ©2021 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting byElsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/ licenses/by-nc-nd/4.0/). application/pdf
institution Nanyang Technological University
building NTU Library
continent Asia
country Singapore
Singapore
content_provider NTU Library
collection DR-NTU
language English
topic Engineering::Civil engineering
Grain Size
Rock Strength
spellingShingle Engineering::Civil engineering
Grain Size
Rock Strength
Peng, Jun
Wong, Louis Ngai Yuen
Teh, Cee Ing
Influence of grain size on strength of polymineralic crystalline rock : new insights from DEM grain-based modeling
description Grain size effect on rock strength is a topic of great interest in geotechnical engineering. A consensus obtained from earlier laboratory tests is that rock strength generally decreases with the increase of grain size for both silicate and carbonate rocks; however, some recent numerical results conflict with such laboratory test results. To address this intriguing issue, the effect of grain size on strength of polymineralic crystalline rock with low porosity is investigated numerically using the grain-based modeling (GBM) approach in discrete element method (DEM) by interpreting micro-cracking process in response to loading. In agreement with some previous DEM simulation results, the simulated rock strength is found to increase with increasing grain size for both homogeneous and heterogeneous models, even when the number of assembled disks in one mineral grain changes. The mechanism of strength increase with increasing grain size is mainly associated with the number of assembled smooth-joint contacts along grain interfaces and the generation of grain boundary cracks in response to loading. The grain interfaces significantly weaken the integrity of the rock model, which is similar to effects of inherent defects in real rock. As the grain size increases, fewer grain interfaces are built in the model and the rock strength becomes much higher. Hence, by solely changing the mineral grain size in a model, the mechanism of grain size effect as observed in laboratory tests cannot be replicated. To address this issue, a method of degradation of grain boundary strength parameters is used to mimic the possible mechanism of grain size effect. The simulated strength using the method becomes comparable with those obtained from laboratory tests when the heterogeneity in the rock is considered. Degradation of grain boundary parameters with increasing grain size provides a plausible explanation for the grain size effect on rock strength.
author2 School of Civil and Environmental Engineering
author_facet School of Civil and Environmental Engineering
Peng, Jun
Wong, Louis Ngai Yuen
Teh, Cee Ing
format Article
author Peng, Jun
Wong, Louis Ngai Yuen
Teh, Cee Ing
author_sort Peng, Jun
title Influence of grain size on strength of polymineralic crystalline rock : new insights from DEM grain-based modeling
title_short Influence of grain size on strength of polymineralic crystalline rock : new insights from DEM grain-based modeling
title_full Influence of grain size on strength of polymineralic crystalline rock : new insights from DEM grain-based modeling
title_fullStr Influence of grain size on strength of polymineralic crystalline rock : new insights from DEM grain-based modeling
title_full_unstemmed Influence of grain size on strength of polymineralic crystalline rock : new insights from DEM grain-based modeling
title_sort influence of grain size on strength of polymineralic crystalline rock : new insights from dem grain-based modeling
publishDate 2021
url https://hdl.handle.net/10356/153533
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