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Outline
Taking the ultra-fine mine tailings as the experimental research object, the optimum mass concentration of the slurry under the conditions of gravity flow and pumping was explored through slump tests, strength ratio tests and response surface analysis. The key factors affecting the compressive strength of the backfill were analyzed, and the NGO-BP neural network model was used to predict the strength of the specimen. The results show that the optimum mass concentration is about 74％ when the pump pressure is transported, and the optimum mass concentration is about 70％ when the gravity flow is transported. When the cement-sand ratio is 1:4, 1:6, 1:8 and 1:20, the 7 d strength of the backfill at each mass concentration reaches 0.8 MPa, and the 28 d strength reaches 1.5 MPa, which meets the strength requirements. When the cement-sand ratio remains unchanged, the strength of the specimen will increase with the increase of mass concentration and the extension of curing age. When other variables remain unchanged, the effect of cement-sand ratio on the strength of the specimen is particularly obvious. The higher the cement-sand ratio, the higher the strength of the specimen. The average absolute error (MAE), average relative percentage error (MAPE), mean square error (MSE), root mean square error (RMSE) predicted by NGO-BP neural network decreases by 0.47, 0.70, 0.96, 0.66, respectively, and the coefficient of determination (R2) increases by 0.26 compared with BP neural network at 7 d of curing. NGO-BP neural network model can be used to guide the filling ratio of production practice, and provide a new idea for the optimization of filling ratio.
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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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