The shear mechanical behavior of red sandstone specimens with prefabricated V-shaped fractures was systematically investigated via laboratory shear tests and numerical simulations, from the perspectives of strength parameters, crack-initiation locations, coalescence modes and stress-field evolution. The results show that the deterioration of internal friction angle and cohesion of specimens is the most significant when the crack opening angle α=110° and azimuth angle β=0°. The finally formed fracture surfaces with coalescence in specimens are parallel to the shear direction, whereas the crack-initiation locations are strongly controlled by the azimuth angle β. The stress-field distribution shows clear zoning behavior:the low-stress zone presents an inclined S shape, while high-stress and shear-stress zones concentrate at fracture tips and end boundaries. From the mesoscopic perspective, principal stresses dominate the development of wing fractures, and the coupled compression-shear effect is the fundamental cause for the generation of secondary fractures.
| 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 |