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| Meso-structural characteristics and fracture mechanism of Three Gorges granite based on in-situ CT scanning |
| ZHU Zeqi1, 2, 3, TIAN Kaiwei1, 2, LI Zishuo4, SHENG Qian1, 2, CHEN Jian1, 2, 3 |
(1. State Key Laboratory of Geomechanics and Geotechnical Engineering Safety, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan, Hubei 430071, China; 2. University of Chinese Academy of Sciences, Beijing 100049, China;
3. National and Local Joint Engineering Research Center for Underwater Tunnel Technology, Wuhan, Hubei 430071,
China; 4. CCTEB Infrastructure Construction Investment Co., Ltd., Wuhan, Hubei 430064, China)
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Abstract In situ CT testing was conducted on two typical types of granite from the Three Gorges region, specifically medium coarse-grained and medium fine-grained granite. Non-invasive measurement of the internal deformation field of rock samples was achieved using digital volume correlation (DVC) technology. This study examined the influence of the microstructural characteristics of granite on its macroscopic mechanical properties and failure modes. The results indicate that the difference in microstructure between medium coarse-grained and medium fine-grained granites is primarily manifested in the directional arrangement of mica. Mica minerals generally exhibit a flat ellipsoidal structure, and the mica particles in medium coarse-grained granites are flatter in shape compared to those in medium fine-grained granites, suggesting a more pronounced spatial directional arrangement of mica in the former. The fracture network of medium and fine-grained granite displays an isotropic distribution, with the fracture mode being stress-controlled. The orientation of the fracture surface in medium coarse-grained granite closely aligns with the orientation and arrangement of mica, demonstrating typical structural control failure. Areas exhibiting larger equivalent strain changes correlate well with the post-peak fracture morphology of the rocks, indicating that equivalent strain can effectively predict the actual fracture morphology of post-peak rocks. In medium coarse-grained granite, regions with equivalent strain changes exceeding 0.4% are identified as potential failure areas, with their distribution patterns aligning closely with the direction of mica arrangement, revealing the dominant role of the mesostructure of granite in its fracture process.
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2025, Vol. 44 
