关键词: 顺倾斜坡；反倾斜坡；振动台试验；地震加速度峰值（peak ground acceleration, 简称PGA）放大系数；破坏模式；损伤识别

Abstract: In the challenging and perilous mountainous regions of Southwest China, there are numerous layered and fractured rock slopes with varying inclinations. These slopes are prone to disasters such as collapses and landslides during earthquakes, posing a serious threat to the ongoing construction of the Sichuan-Xizang Railway. To address this issue, large-scale shaking table model tests were conducted to study the dynamic response, failure modes of instability, and energy transfer characteristics of dip and anti-dip layered slopes under strong earthquake conditions. The test results reveal that the anti-seismic performance of anti-dip slopes is significantly better than that of dip slopes. The failure mode of dip slopes primarily involves tensile cracking, shearing, uplift, and slip failure. On the other hand, the failure mode of anti-dip slopes mainly consists of tensile, bending, tilting, and collapsing failure. The natural vibration frequency of anti-dip slopes is higher compared to dip slopes. As the earthquake magnitude increases, the natural frequency of dip slopes gradually decreases. However, the natural frequency of anti-dip slopes exhibits repeated oscillations within the range of seismic amplitudes of from 0.4g to 0.7g. Dip slopes exhibit clear “elevation amplification effect” and “tend-surface effect,” while anti-dip slopes demonstrate the “elevation amplification effect.” Furthermore, the internal acceleration response is greater than that of the slope surface. Marginal spectrum identification indicates that the most significant change in peak of marginal spectrum amplitude (PMSA) for dip slopes occurs at the upper part of the slope waist. This suggests that the energy loss of seismic waves near this position is the largest, indicating the formation of a sliding failure surface near the upper part of the slope waist. For anti-dip slopes, the PMSA decreases most significantly at the slope shoulder, indicating severe damage and a propensity for local collapse in this area. The analysis results are in good agreement with the experimental observations, providing further insights into the dynamic response and instability failure modes of different structural types of layered slopes under strong earthquakes. These findings serve as a basis for ensuring the safe construction of the Sichuan-Xizang Railway.

Key words: dip slope, anti-dip slope, shaking table test, peak ground acceleration (PGA) amplification coefficient, failure mode, damage identification