Effect of Weak Structural Planes on the Seismic Response Characteristics and Failure Mechanism of High‐Steep Rock Slopes via the Time–Frequency Joint Analysis Method

ABSTRACT To investigate the effects of weak structural planes on the seismic response characteristics and failure mechanism of high‐steep rock slopes, a time–frequency joint analysis method is proposed on the basis of the time, frequency and time‐frequency domains. Four models, a homogeneous slope (Model 1), a horizontal layered slope (Model 2), an anti‐dip slope (Model 3) and a bedding slope (Model 4), were established for numerical simulation via FLAC3D. The time‐domain analysis shows that the structural planes contribute significantly to the dynamic response of the slopes. Seismic waves passing through a structural plane generate local amplification and attenuation, and the effects of different dip directions follow the order of anti‐dip > horizontal layered > bedding. In addition, frequency‐domain analysis revealed that the low‐frequency components (< 5 Hz) and high‐frequency components (> 11 Hz) caused the overall and local dynamic deformation of the slopes, respectively. The distribution and dip direction of structural planes determine the failure modes of slopes. Complete ensemble empirical mode decomposition with adaptive noise and Hilbert transform methods (CEEMDAN‐HTs) were proposed as the improved Hilbert–Huang transform (HHT) to process seismic signals for time–frequency domain analysis, and the seismic energy in the marginal spectrum is distributed mainly in the low‐frequency section. The time–frequency joint analysis method shows that the acceleration response and the marginal spectrum reflect the local and overall dynamic failure characteristics of the slopes, respectively. The local and overall dynamic instability probabilities of the slopes follow the order of bedding slope > anti‐dip slope > horizontal layered slope > homogeneous slope.