Numerical evaluation of ground motion amplification of rock slopes under obliquely incident seismic waves

The incident angle of the seismic waves has a significant influence on the seismic response of rock slopes. However, the details of the interactions between oblique seismic waves and slopes are not well understood. The objective of this study is to quantitatively evaluate the amplification of the peak ground acceleration (PGA) and spectral acceleration (SA) of rock slopes under obliquely incident seismic waves. The incident wave field was implemented in the commercial software ABAQUS based on the equivalent nodal force method and viscousspring artificial boundary theory. Two test examples simulating the propagation of oblique SV waves were used to verify the validity and accuracy of the proposed method. An extensive parametric study consisting of 375 simulation cases was performed by considering the slope height, slope angle, and incident angle of the seismic waves. The results reveal that for different incident waves, the maximum amplification factors of PGA and SA under oblique incidence of seismic waves are generally 1.4-2.2 and 1.7-1.9 times those under vertical incidence, respectively. Statistical analysis of the amplification factors indicated that the amplification effects were not positively correlated with slope height, but generally increased with increasing slope angle and incident angle of the seismic waves. In contrast, the spectral periods corresponding to the maximum SA amplification factors showed a strong positive correlation with the slope height but were less sensitive to the slope angle and incident angle of the seismic waves. The findings emphasized the significance of slope geometry and incident direction of seismic waves in ground motion amplification, which may provide quantitative insights and useful references for seismic design in slope engineering.