When drilling and blasting are adopted for excavation of high slopes, blasting-induced vibration signals are susceptible to noise interference and their effective features are difficult to extract accurately, a noise reduction method based on complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN) combined with wavelet threshold is proposed. Blasting vibration signals are reprocessed based on mean ratio (MR), sample entropy, and correlation coefficient. The proposed method is verified by simulated and field measured blasting vibration signals. The simulation results show that the signal-to-noise ratio (SNR) of the proposed method reaches 27.80 dB and the root-mean-square error (RMSE) is 0.209 1, presenting a superior noise-reduction performance compared to the other four methods. Engineering application results indicate that this proposed method can effectively suppress high-frequency noise and improve the resolution and stability of time-frequency analysis for blasting vibration signals. Further analysis reveals that the dominant frequency of blasting vibration signals is mainly within the range of 10-60 Hz with energy concentrated within 16-125 Hz; the dominant frequency of rockfall impact signals is mostly in the range of 40-720 Hz with more complex spectral structures, and its energy is mainly distributed in 62-1 000 Hz.
| 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 |