Seismic response analysis of a bedding rock slope based on the time-frequency joint analysis method: a case study from the middle reach of the Jinsha River, China

To investigate the seismic response of a bedding rock slope, a time-frequency joint analysis method was proposed using the finite element method (FEM) based on the time, frequency, and time-frequency domains. According to the time-frequency joint analysis, the results show that the topographic and geological conditions have great impacts on the dynamic response characteristics of the slope. An obvious slope surface and elevation amplification effect can be observed during earthquake excitation. The bedding structural plane has a great influence on the characteristics of wave propagation through the slope. The impacts of the structural plane and wave propagation directions on the seismic response of the slope are discussed. In addition, dynamic deformation characteristics and the natural frequency of the slope are clarified according to the Fourier spectrum and modal analysis. Low-order and high-order natural frequencies mainly cause the overall and local dynamic deformation of the surface slope, respectively. Moreover, the seismic energy of the Hilbert energy spectrum and marginal spectrum is mainly concentrated in the low-order and high-order natural frequency components, respectively. The difference in the seismic response between the slip mass and slip bed is the main triggering factor of a landslide based on the time-frequency joint analysis. The dynamic failure mechanism of the slope is identified: cracks first occur in the structural planes; then, with the earthquake excitation continuing, cracks further expand, deepen and penetrate, thus gradually forming the slip plane; finally, the overall shear failure of the surface slope appears.