Shear behavior and off-fault damage of saw-cut smooth and tension-induced rough joints in granite
The damage of rock joints or fractures upon shear includes the surface damage occurring at the contact asperities and the damage beneath the shear surface within the host rock. The latter is commonly known as off-fault damage and has been much less investigated than the surface damage. The main cont...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
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Elsevier
2024-04-01
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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/S1674775523002184 |
| _version_ | 1797203045020336128 |
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| author | Fanzhen Meng Feili Wang Louis Ngai Yuen Wong Jie Song Muzi Li Chuanqing Zhang Liming Zhang |
| author_facet | Fanzhen Meng Feili Wang Louis Ngai Yuen Wong Jie Song Muzi Li Chuanqing Zhang Liming Zhang |
| author_sort | Fanzhen Meng |
| collection | DOAJ |
| description | The damage of rock joints or fractures upon shear includes the surface damage occurring at the contact asperities and the damage beneath the shear surface within the host rock. The latter is commonly known as off-fault damage and has been much less investigated than the surface damage. The main contribution of this study is to compare the results of direct shear tests conducted on saw-cut planar joints and tension-induced rough granite joints under normal stresses ranging from 1 MPa to 50 MPa. The shear-induced off-fault damages are quantified and compared with the optical microscope observation. Our results clearly show that the planar joints slip stably under all the normal stresses except under 50 MPa, where some local fractures and regular stick-slip occur towards the end of the test. Both post-peak stress drop and stick-slip occur for all the rough joints. The residual shear strength envelopes for the rough joints and the peak shear strength envelope for the planar joints almost overlap. The root mean square (RMS) of asperity height for the rough joints decreases while it increases for the planar joint after shear, and a larger normal stress usually leads to a more significant decrease or increase in RMS. Besides, the extent of off-fault damage (or damage zone) increases with normal stress for both planar and rough joints, and it is restricted to a very thin layer with limited micro-cracks beneath the planar joint surface. In comparison, the thickness of the damage zone for the rough joints is about an order of magnitude larger than that of the planar joints, and the coalesced micro-cracks are generally inclined to the shear direction with acute angles. The findings obtained in this study contribute to a better understanding on the frictional behavior and damage characteristics of rock joints or fractures with different roughness. |
| first_indexed | 2024-04-24T08:13:05Z |
| format | Article |
| id | doaj.art-9c93787270da445984fb17ddbdaac5c0 |
| institution | Directory Open Access Journal |
| issn | 1674-7755 |
| language | English |
| last_indexed | 2024-04-24T08:13:05Z |
| publishDate | 2024-04-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Journal of Rock Mechanics and Geotechnical Engineering |
| spelling | doaj.art-9c93787270da445984fb17ddbdaac5c02024-04-17T04:48:58ZengElsevierJournal of Rock Mechanics and Geotechnical Engineering1674-77552024-04-0116412161230Shear behavior and off-fault damage of saw-cut smooth and tension-induced rough joints in graniteFanzhen Meng0Feili Wang1Louis Ngai Yuen Wong2Jie Song3Muzi Li4Chuanqing Zhang5Liming Zhang6College of Science, Qingdao University of Technology, Qingdao, 266033, ChinaCollege of Science, Qingdao University of Technology, Qingdao, 266033, ChinaDepartment of Earth Sciences, The University of Hong Kong, Pokfulam, Hong Kong, China; Corresponding author.College of Science, Qingdao University of Technology, Qingdao, 266033, ChinaCollege of Science, Qingdao University of Technology, Qingdao, 266033, ChinaState Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan, 430071, ChinaCollege of Science, Qingdao University of Technology, Qingdao, 266033, China; Cooperative Innovation Center of Engineering Construction and Safety Shandong Peninsula Blue Economic Zone, Qingdao, 266033, ChinaThe damage of rock joints or fractures upon shear includes the surface damage occurring at the contact asperities and the damage beneath the shear surface within the host rock. The latter is commonly known as off-fault damage and has been much less investigated than the surface damage. The main contribution of this study is to compare the results of direct shear tests conducted on saw-cut planar joints and tension-induced rough granite joints under normal stresses ranging from 1 MPa to 50 MPa. The shear-induced off-fault damages are quantified and compared with the optical microscope observation. Our results clearly show that the planar joints slip stably under all the normal stresses except under 50 MPa, where some local fractures and regular stick-slip occur towards the end of the test. Both post-peak stress drop and stick-slip occur for all the rough joints. The residual shear strength envelopes for the rough joints and the peak shear strength envelope for the planar joints almost overlap. The root mean square (RMS) of asperity height for the rough joints decreases while it increases for the planar joint after shear, and a larger normal stress usually leads to a more significant decrease or increase in RMS. Besides, the extent of off-fault damage (or damage zone) increases with normal stress for both planar and rough joints, and it is restricted to a very thin layer with limited micro-cracks beneath the planar joint surface. In comparison, the thickness of the damage zone for the rough joints is about an order of magnitude larger than that of the planar joints, and the coalesced micro-cracks are generally inclined to the shear direction with acute angles. The findings obtained in this study contribute to a better understanding on the frictional behavior and damage characteristics of rock joints or fractures with different roughness.http://www.sciencedirect.com/science/article/pii/S1674775523002184Planar jointRough jointShear behaviorOff-fault damageMicro-cracks |
| spellingShingle | Fanzhen Meng Feili Wang Louis Ngai Yuen Wong Jie Song Muzi Li Chuanqing Zhang Liming Zhang Shear behavior and off-fault damage of saw-cut smooth and tension-induced rough joints in granite Journal of Rock Mechanics and Geotechnical Engineering Planar joint Rough joint Shear behavior Off-fault damage Micro-cracks |
| title | Shear behavior and off-fault damage of saw-cut smooth and tension-induced rough joints in granite |
| title_full | Shear behavior and off-fault damage of saw-cut smooth and tension-induced rough joints in granite |
| title_fullStr | Shear behavior and off-fault damage of saw-cut smooth and tension-induced rough joints in granite |
| title_full_unstemmed | Shear behavior and off-fault damage of saw-cut smooth and tension-induced rough joints in granite |
| title_short | Shear behavior and off-fault damage of saw-cut smooth and tension-induced rough joints in granite |
| title_sort | shear behavior and off fault damage of saw cut smooth and tension induced rough joints in granite |
| topic | Planar joint Rough joint Shear behavior Off-fault damage Micro-cracks |
| url | http://www.sciencedirect.com/science/article/pii/S1674775523002184 |
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