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Tingting Liu is a Professor at the School of Civil Engineering and Architecture, Wuhan University of Technology, China. She received her BSc degree from Zhengzhou University and PhD degree from the Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Her research interests encompass dynamic mechanical behavior of deep jointed rock masses, stress wave propagation across rock joints, prediction of blasting vibration, and safety assessment methodologies for deep underground surrounding rock.
Outline
During geotechnical construction, flawed rock masses experience dynamic cyclic disturbances, leading to cumulative deformation and progressive damage. Consequently, elucidating the fracture mechanisms under cyclic loading is crucial for ensuring the safety and prolonged operation of deep underground engineering. This study investigated the mechanical responses of the surrounding rock at different locations by conducting triaxial tests on flawed granite using three distinct cyclic loading and unloading paths. Based on the maximum tangential stress criterion, a fracture mechanics model for open flaws was developed to analyze the intrinsic influence of confining pressure and flaw inclination on crack initiation behavior. The results indicate that graded unloading of confining pressure significantly weakens the flawed rock mass, reducing its peak stress to only 77.5 % of that observed under constant confining pressure. Conversely, flawed rock masses exhibit a substantial increase in bearing capacity under increasing graded cyclic loading, achieving a peak stress 19.3 % higher than that under cyclic disturbance loading. At a constant confining pressure of 40 MPa, the type of disturbance loading has no significant effect on the failure mode. The flawed granite specimens form a nearly V-shaped shear failure zone along the open flaw. However, confining pressure unloading induced a more complex shear-tensile composite failure mode in the specimens. The crack initiation angle increases nonlinearly with confining pressure, but decreases gradually as the flaw inclination angle (β) increases. These findings provide valuable insights for the safe construction of deep underground engineering.
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| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |
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