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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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 |
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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 |
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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. |
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School of Civil and Environmental Engineering |
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School of Civil and Environmental Engineering Peng, Jun Wong, Louis Ngai Yuen Teh, Cee Ing |
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Article |
author |
Peng, Jun Wong, Louis Ngai Yuen Teh, Cee Ing |
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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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1718928708665868288 |