Numerical investigation on seismic response characteristics and deformation mechanism of high-steep rock slopes containing weak structural planes using time-frequency joint analysis

The time-frequency joint analysis method was used to study the seismic response characteristics of high-steep rock slopes with weak structural planes. Two models of homogeneous slopes and anti-dip slopes were established using FLAC3D. The results of the time-frequency joint analysis reveal that the topography, geological conditions and seismic wave propagation directions strongly influence the seismic response characteristics of the slopes. The high slope dynamic response of a homogeneous slope shows that the peak ground acceleration (PGA) periodically changes in a certain pattern with elevation and is obviously amplified at the slope crest. Weak structural planes cause local amplification and attenuation of seismic waves, while the two effects of horizontal seismic waves are greater than those of vertical seismic waves when passing through weak structural planes. Frequency-domain analysis reveals that the direction of seismic wave propagation notably affects the value and variation rule of the peak Fourier spectrum amplitude (PFSA), while weak structural planes strongly affect only this value. The dynamic deformation characteristics of the slopes are clarified according to Fourier spectrum analysis and modal analysis. The low-frequency components and high-frequency components mainly cause overall and local deformations, respectively, of the surface slope. In addition, the dynamic response characteristics of the slopes are further analysed based on Hilbert energy, and the applicability of the seismic Hilbert energy spectrum to reflecting the dynamic deformation characteristics of the slopes is determined. Moreover, the connection between the local deformation of the anti-dip slope and the occurrence of a landslide was discussed.