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On-site double-hole slitting blasting experiments were conducted to study the effect of controlling fracture damage by double-hole slitting blasting. A test double hole slitting blasting model was constructed using ANSYS/LS-DYNA software, and its crack propagation and changes in gas unit pressure on the hole wall were compared and analyzed. The on-site results indicate that an intersecting fracture surface is formed between the two blast holes in the direction of the cutting seam after the explosion, and the half-hole residue is more obvious. Besides, the cracks will still develop towards the cutting direction by changing the cutting angle to 157°, and the guiding effect of the cutting seam is not affected by the change in angle. Meanwhile, the fracturing effect of adding empty holes between blast holes is better than that of non-empty hole slot blasting, which indicates that the existence of empty holes can effectively improve the directional fracture effect of slot blasting. The model results of the crack propagation and damage are consistent with the on-site results. By comparing and analyzing the double hole slit blasting and ordinary smooth blasting models, the superposition effect of stress waves causes the development of cracks between the holes to deflect, which forms a crack void between the two holes. Though analyzing the peak pressure of gas units around the hole wall at 0°~90°, it is found that the time when the pressure peak reaches the slit direction is earlier than that in the non-slit direction. More importantly, the pressure peak decreased significantly, and then the curve gradually tended to flatten during the slit blasting range of 0°~15°. The larger the angle, the smaller the peak change. The slit tube effectively controls the distribution of explosion energy during the explosion process, which forms stress concentration at the slit, with the maximum stress peak being about four times higher than that in the vertical direction.
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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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