关键词: 振动台试验, 边坡工程, 顺层岩质斜坡, 软弱夹层, 动力响应, HHT时频分析

Abstract: In this study, the “Xiaguiwa” landslide in Jinsha River Basin of Qinghai-Tibet Plateau is taken as a prototype, and the shaking table model test on bedding rock slope with weak interlayer is carried out. The dynamic response of bedding rock slope with weak interlayer under earthquake is studied from the aspects of peak ground acceleration (PGA) amplification factor and Hibert-Huang transform (HHT) time-frequency characteristics. The results show that the slope exhibits obvious “elevation effect” and “surface effect” under the action of input seismic waves. The PGA is larger at the 1/4 height of the slope surface from the bottom of the slope, the top of the slope, and the weak interlayer. With the increase of the intensity of the input seismic waves, the slope stiffness and natural vibration frequency decrease gradually. When the input wave amplitude reaches 0.7g, the slope cracking and structural deformation occur. When the input amplitudes are the same, the PGA amplification coefficient is positively correlated with the elevation, and decreases gradually with the increase of the input amplitudes at the same measuring point. The influences of different input wave types and time scale factors on the slope dynamic response are significantly different. The Hilbert spectrum shows that the elevation and weak interlayer amplify the energy of seismic waves, especially the high-frequency part. The Hilbert marginal spectrum shows that the weak interlayer could amplify the energy of the high-frequency part. The Hilbert marginal spectrum indicates that the cumulative energy of the high-frequency part is significantly amplified under the influence of soft interlayer, and the energy of the measuring point at the 1/4 height of the slope surface from the bottom of the slope suddenly increases, which is similar to the conclusion of the acceleration amplification effect. The results of Hilbert marginal spectrum shows that with the increase of the amplitude of the input seismic wave, the cumulative energy of the high-frequency part and the part representing the natural vibration frequency of the slope gradually decrease, and the energy of the main frequency part of the input seismic wave gradually dominates, indicating that the modal characteristics of the slope gradually disappear.

Key words: shaking table tests, slope engineering, bedding rock slope, weak interlayer, dynamic response, HHT time-frequency analysis