Analysis of the effects of slope geometry on the dynamic response of a near-field mountain from the Wenchuan Earthquake

Fourier spectra and acceleration response spectra of near-field acceleration records of the 2008 Wenchuan Earthquake have been calculated. Relative fundamental frequencies (or predominant periods) were characterized. Then, the natural frequencies of a range of slopes with different geometric characteristics, such as height, slope ratio, and pattern, were analyzed. The seismic responses of the slopes were compared, and the variability of seismic response with the above geometric elements was found. Results show that if slope height increases, and provided that other conditions are unchanged, the natural frequency of the first mode of a double-surface slope will change as a power law. However, natural frequencies will diminish (based on a parabolic function) as the slope angle becomes large. Both the surface pattern and the number of surfaces on a slope can have a great impact on the seismic response of the slope. Moreover, within a certain range of slope heights or angles, either height or angle will also greatly influence the variability of the seismic response. The results of this research will be helpful to understanding seismic dynamic response features and explaining the ways that slope stability can be affected by earthquakes