## 4 Conclusions  
In order to extend the research and methodically uncover the seismic dynamic response characteristics of the steep bedding rock slope (SBRS), this paper has performed a dynamic numerical simulation based on the slope shaking table experiments carried out early in our study. It should be pointed out that we maintained great consistency in the size and physical parameters between the shaking table model and the numerical simulation model throughout the modeling process to guarantee the accuracy of the numerical simulation results. The following conclusions are drawn from a systematic analysis of the dynamic response characteristics of the SBRS under the action of an earthquake from an energy point of view using the Hilbert-Huang transform and marginal spectrum theory:  
1. The acceleration amplification factor \(AAF\) of the slope under seismic action shows an obvious 'elevation effect' and'surface effect'. Simultaneously, the slope surface monitoring point's acceleration Fourier spectrum gradually changes from a single peak to a double peak as its elevation rises. The amplitude of the high-frequency peak is more noticeable with the elevation amplification effect than the low-frequency peak, indicating that the slope acceleration Fourier spectrum's amplification effect is somewhat selective. 2. Both the elevation and weak layers amplify the transmission of Hilbert energy, and the comparison of the Hilbert spectrums of an SBRS with weak layers and a homogeneous slope reveals a greater amplification of the high-frequency component of Hilbert energy. Because of this, the weak layer at the top of the slope is often damaged first when an earthquake happens. The final instability of the SBRS results from the progressive extension of the tensile fractures in the slope downhill and the progressive cutting and joining of the locked section at the toe of the slope. Figure 13: Marginal spectra of monitoring points under action of seismic waves of different amplitudes: (**a**) marginal spectrum of monitoring point M4 and (**b**) marginal spectrum of monitoring point M9. 3. The peak value of the marginal spectrum's Hilbert energy corresponding to the main earthquake frequency will be considerably boosted as the seismic wave amplitude grows, according to a comparison of the SBRS's marginal spectrum under different seismic wave amplitudes. This implies that when the Hilbert energy of the marginal spectrum being regulated by seismic waves progressively takes over, the slope is harmed and distorted. Additionally, there is a precursor even though there is no penetration damage because the Hilbert energy in the high-frequency band of the marginal spectrum at the locked segment's upper monitoring point will suddenly rise before penetration damage occurs in the locked segment close to the base of the slope. This suggests that the top portion of the internal portion of the locked section has begun to sustain damage. Finally, we have not been able to provide a universal index that would enable us to identify the unstable area of this type of slope, even though this article has extensively investigated the dynamic response characteristics of the SBRS from an energy perspective using the Hilbert-Huang transform and marginal spectrum theory. In order to predict when this kind of slope would become unstable, we will try to evaluate its condition using a specific energy index in our future studies. Conceptualization, Z.L. and L.X. ; methodology, K.H. ; software, L.L. ; validation, Z.L., K.H. and L.L. ; investigation, L.X. ; resources, J.D. ; data curation, C.W. ; writing--original draft preparation, Z.L. and L.X. ; writing--review and editing, L.X. and T.J.; supervision, H.D. ; project administration, Z.L. ; funding acquisition, L.X. All authors have read and agreed to the published version of the manuscript. This research was funded by the National Natural Science Foundation of China, grant numbers 42090052 and 41977249, and the National Key Research and Development Program of China, grant number 2019 YFC1509701. Not applicable.