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In order to investigate the spatio-temporal evolution of mining-induced fissures and change characteristics of pressure relief gas-enriched area in the overlying rock of the slowly inclined coal bed，physical similarity simulation and field monitoring method were used to analyze the evolution and distribution characteristics of the fissure in the overlying rock. The evolution characteristics of the pressure relief gas-enriched area were studied to determine the parameter arrangement scheme of the high directional drilling holes，and the effect test was carried out. The results show that the test working face has a height of 13 m along the caving zone of the coal bed，and the height of the fissure zone is 68.5 m. The fissure network along the working face is affected by the inclination angle of the coal bed，and the fracture angle of the working face is 54°-59°. The openness of the fissure development is gradually increasing upward from the working face，and the gas transportation channel is asymmetric. The whole life cycle of the gas extraction process by high directional drilling can be divided into the early stage of extraction，the middle stage of extraction，and the end stage of extraction according to the extraction volume fraction. In the early stage of extraction，the volume fraction is low. The middle stage of extraction has high efficiency in the whole life cycle of extraction. In the late stage of extraction，the volume fraction shows a sharp decline. After the implementation of the high directional and long drilling technology，the volume fractions of the gas in the upper corners of the working face and in the return-air tunnel are all less than 0.8%，indicating a good effect of the gas extraction，and the arrangement of the high drilling holes is reasonable.
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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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