Assessing the influence of a rapid water drawdown on the seismic response characteristics of a reservoir rock slope using time–frequency analysis

Abstract

To investigate the influence of a rapid water drawdown (RWD) on the seismic response characteristics of reservoir rock slopes, numerical dynamic analyses and shaking table tests are conducted on a rock slope containing discontinuities under a RWD using time–frequency analysis from the perspective of spectral and energy propagation characteristics. The results show that a RWD has a magnification effect on the seismic response of a surface slope, which is mainly manifested as the RWD causing the seismic energy of the surface slope to increase significantly. The RWD has a magnification effect on the Fourier spectrum amplitude of the low-order natural frequency band. A time–frequency domain analysis shows that the RWD has an influence on the characteristics of the seismic Hilbert energy spectrum (HES) in the low-frequency band of the surface slope and magnifies the amplitude of the marginal spectrum (MS) in the high-frequency band. In addition, the applicability of the Fourier spectrum, HES and MS in analysing the relationship between the RWD and the slope dynamic response is discussed. An analysis of the seismic HES shows that the RWD has a major impact on the overall dynamic response of the surface slope, while the RWD has a significant impact on the local dynamic response of the surface slope based on the Fourier spectrum and the MS. The influence mechanism of the RWD on the HES and MS of the slope is also discussed. Moreover, the influence of a RWD on the development process of seismic damage to the slope is clarified using an energy-based method.