## 4 Conclusions  
In this study, conducted in the backdrop of the 3310 working face in the ancient city coal mine, the FFT method and MEDFA were employed to analyze the spectral characteristics and multifractal features of different types of dynamic load waveforms. Through Flac3D dynamic mode simulation, the propagation and attenuation characteristics of different types of dynamic load waves were analyzed, shedding light on dynamic disasters such as strong dynamic load-induced ground pressure impacts in mines. The research findings obtained in this study are summarized as follows:  
1. Based on the Brune model, the seismic source parameters of strong dynamic loads were estimated and analyzed. It was found that the seismic moment and radiated energy of various types of dynamic loads are positively correlated. Under the same conditions of radiated energy, the seismic moment is the greatest for coal pillar-type dynamic loads, followed by roof-type dynamic loads, with fault-type dynamic loads being the smallest. Additionally, under the same seismic source radius conditions, fault-type dynamic loads result in the largest increase in volume due to non-elastic deformation of the rupture source, followed by coal pillar-type dynamic loads, and then roof-type dynamic loads. Fault-type dynamic loads have the smallest rupture strength and scale, but exhibit higher stress drops, with the greatest magnitude of stress level adjustment or release, followed by coal pillar-type dynamic loads, and then roof-type dynamic loads. 2. Based on the analysis of the frequency spectrum and multifractal features of strong dynamic load waveforms using FFT and MEDFA, it was found that the first dominant frequency of the three types of strong dynamic loads tends to cluster. Based on this, it is inferred that the frequency boundary lines of the three types of signals lie within the range of 30-60 HZ. The post-peak decay coefficients of the waveforms for the three types of strong dynamic load events differ, with average values for roof-type, coal pillar-type, and fault-type being 1.41, 1.57, and 4.53, respectively. Regarding multifractal features, coal pillar-type strong dynamic load waves exhibit the highest degree of waveform fluctuation, followed by roof-type, and then fault-type. 3. Numerical simulations were conducted to analyze the dynamics of three typical types of strong dynamic loads, obtaining velocity response characteristics during their propagation. The results indicated that during the propagation process, the frequency attenuation regions differ: roof-type dynamic load waves exhibit significant attenuation in the low-frequency range (from 0 Hz to 35 Hz), while fault-type dynamic load waves show broader significant attenuation (from 0 Hz to 80 Hz). Coal pillar-type dynamic load waves exhibit attenuation regions similar to fault-type, but with the fastest attenuation in the 0-10 Hz range, where low-frequency components rapidly decay during propagation. Furthermore, peak vibration velocity decreases with increasing propagation distance, with attenuation coefficients of 0.0034, 0.0027, and 0.0018 for roof-type, fault-type, and coal pillar-type dynamic load waves, respectively. Although this study has preliminarily revealed the source characteristics, spectral laws, and propagation characteristics of strong dynamic load events in deep mining, there are still many directions worthy of further exploration. Future research can continue, combining artificial intelligence and big data technology to build an intelligent recognition model for dynamic load signals and further optimizing the automatic classification accuracy of source types through deep learning algorithms. In addition, future studies may explore the quantitative relationship between different types of dynamic load events and surrounding rock fractures and energy release, providing dynamic threshold standards for disaster prediction.