Anisotropic mechanical characterization of gneissic rock from Canadian Shield: Bridging the micro- and meso-scale gap
The microstructure and fabric of rocks largely control their mechanical behavior, and their spatial variations can lead to anisotropic behavior. Metamorphic rocks such as gneiss exhibit anisotropy, and characterizing this anisotropy is crucial in geoscientific and engineering applications including...
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| Format: | Article |
| Language: | English |
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Elsevier
2025-08-01
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| Series: | Journal of Rock Mechanics and Geotechnical Engineering |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S1674775525000691 |
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| author | Afeez K. Popoola Kareem Ramzy Aboayanah Seyed Mohammad Hosein Seyed Ghafouri Bezawit F. Haile Lei Sun Karl Peterson Giovanni Grasselli |
| author_facet | Afeez K. Popoola Kareem Ramzy Aboayanah Seyed Mohammad Hosein Seyed Ghafouri Bezawit F. Haile Lei Sun Karl Peterson Giovanni Grasselli |
| author_sort | Afeez K. Popoola |
| collection | DOAJ |
| description | The microstructure and fabric of rocks largely control their mechanical behavior, and their spatial variations can lead to anisotropic behavior. Metamorphic rocks such as gneiss exhibit anisotropy, and characterizing this anisotropy is crucial in geoscientific and engineering applications including geothermal plays, active fault zones, and mining sites. We investigate a foliated gneiss from the French River area of the Canadian Shield to determine its mechanical properties and assess the impact of anisotropy across different scales. We combined micro-scale experiments (e.g. nanoindentation and optical and electron microscopy), with meso-scale experiments (e.g. unconfined compressive strength (UCS) and indirect tensile test), to attempt bridging the micro-to meso-scale elastic property gap. Our results show that micro- and meso-mechanical properties of gneiss are orientation-dependent across scales. Young's modulus, upscaled from nanoindentation testing, varied between 51 GPa and 74 GPa, while meso-scale Young's modulus from UCS tests varied between 45 GPa and 54 GPa. The ultrasonic velocities (P- and S-wave) exhibited anisotropy of 26% and 24%, respectively, while the estimated UCS anisotropy was 30%, with the highest values observed in the direction parallel to the foliation. The direction of the mineral alignment forming the foliation plane plays a crucial role in determining the failure pattern of the rock. We observed predominantly tensile failure in samples with 0°–15° foliation plane angle, shear-slip failure for samples with 20°–65°, and a conjugate shear failure in the sample at 90° foliation plane angle to the loading direction. These findings provide insight into the anisotropic (orientation-dependent) characterization of foliated metamorphic rocks, which can be useful in rock engineering applications and numerical simulations. |
| format | Article |
| id | doaj-art-1258313bbac04f8f9cb965deaa09adfe |
| institution | Kabale University |
| issn | 1674-7755 |
| language | English |
| publishDate | 2025-08-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Journal of Rock Mechanics and Geotechnical Engineering |
| spelling | doaj-art-1258313bbac04f8f9cb965deaa09adfe2025-08-20T03:45:11ZengElsevierJournal of Rock Mechanics and Geotechnical Engineering1674-77552025-08-011784784480110.1016/j.jrmge.2025.01.025Anisotropic mechanical characterization of gneissic rock from Canadian Shield: Bridging the micro- and meso-scale gapAfeez K. Popoola0Kareem Ramzy Aboayanah1Seyed Mohammad Hosein Seyed Ghafouri2Bezawit F. Haile3Lei Sun4Karl Peterson5Giovanni Grasselli6Department of Earth Sciences, University of Toronto, Toronto, ON, M5S 3B1, CanadaDepartment of Civil and Mineral Engineering, University of Toronto, Toronto, ON, M5S 1A4, CanadaDepartment of Civil and Mineral Engineering, University of Toronto, Toronto, ON, M5S 1A4, CanadaDepartment of Civil and Mineral Engineering, University of Toronto, Toronto, ON, M5S 1A4, CanadaSchool of Civil Engineering, Wuhan University, Wuhan, 430072, China; Corresponding author.Department of Civil and Mineral Engineering, University of Toronto, Toronto, ON, M5S 1A4, CanadaDepartment of Earth Sciences, University of Toronto, Toronto, ON, M5S 3B1, Canada; Department of Civil and Mineral Engineering, University of Toronto, Toronto, ON, M5S 1A4, CanadaThe microstructure and fabric of rocks largely control their mechanical behavior, and their spatial variations can lead to anisotropic behavior. Metamorphic rocks such as gneiss exhibit anisotropy, and characterizing this anisotropy is crucial in geoscientific and engineering applications including geothermal plays, active fault zones, and mining sites. We investigate a foliated gneiss from the French River area of the Canadian Shield to determine its mechanical properties and assess the impact of anisotropy across different scales. We combined micro-scale experiments (e.g. nanoindentation and optical and electron microscopy), with meso-scale experiments (e.g. unconfined compressive strength (UCS) and indirect tensile test), to attempt bridging the micro-to meso-scale elastic property gap. Our results show that micro- and meso-mechanical properties of gneiss are orientation-dependent across scales. Young's modulus, upscaled from nanoindentation testing, varied between 51 GPa and 74 GPa, while meso-scale Young's modulus from UCS tests varied between 45 GPa and 54 GPa. The ultrasonic velocities (P- and S-wave) exhibited anisotropy of 26% and 24%, respectively, while the estimated UCS anisotropy was 30%, with the highest values observed in the direction parallel to the foliation. The direction of the mineral alignment forming the foliation plane plays a crucial role in determining the failure pattern of the rock. We observed predominantly tensile failure in samples with 0°–15° foliation plane angle, shear-slip failure for samples with 20°–65°, and a conjugate shear failure in the sample at 90° foliation plane angle to the loading direction. These findings provide insight into the anisotropic (orientation-dependent) characterization of foliated metamorphic rocks, which can be useful in rock engineering applications and numerical simulations.http://www.sciencedirect.com/science/article/pii/S1674775525000691AnisotropyMicro-structureNanoindentationDigital image correlation (DIC)Mineral mapGneissic rocks |
| spellingShingle | Afeez K. Popoola Kareem Ramzy Aboayanah Seyed Mohammad Hosein Seyed Ghafouri Bezawit F. Haile Lei Sun Karl Peterson Giovanni Grasselli Anisotropic mechanical characterization of gneissic rock from Canadian Shield: Bridging the micro- and meso-scale gap Journal of Rock Mechanics and Geotechnical Engineering Anisotropy Micro-structure Nanoindentation Digital image correlation (DIC) Mineral map Gneissic rocks |
| title | Anisotropic mechanical characterization of gneissic rock from Canadian Shield: Bridging the micro- and meso-scale gap |
| title_full | Anisotropic mechanical characterization of gneissic rock from Canadian Shield: Bridging the micro- and meso-scale gap |
| title_fullStr | Anisotropic mechanical characterization of gneissic rock from Canadian Shield: Bridging the micro- and meso-scale gap |
| title_full_unstemmed | Anisotropic mechanical characterization of gneissic rock from Canadian Shield: Bridging the micro- and meso-scale gap |
| title_short | Anisotropic mechanical characterization of gneissic rock from Canadian Shield: Bridging the micro- and meso-scale gap |
| title_sort | anisotropic mechanical characterization of gneissic rock from canadian shield bridging the micro and meso scale gap |
| topic | Anisotropy Micro-structure Nanoindentation Digital image correlation (DIC) Mineral map Gneissic rocks |
| url | http://www.sciencedirect.com/science/article/pii/S1674775525000691 |
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