Numerical study on the back slope effect of trapezoidal canyon slope under oblique incidence of P-SV waves

The incident angle of seismic waves influences the dynamic response of rock slopes. However, the relationship between the back-slope effect in strong earthquake areas and the incident angle has not been well-explained. Based on the equivalent nodal force method and the viscoelastic artificial boundary theory, the oblique incidence of seismic P-wave and SV-wave are carried out in FLAC3D software. The accuracy of the proposed method is verified by comparing it with the results of the theoretical solution and another numerical result. The dynamic response of trapezoidal canyon slope under oblique incidence of P-waves and SV-waves was studied, and the effects of different slope angles and canyon widths were analyzed. The study reveals a pronounced back-slope effect under the action of the P-wave and SV-wave, and the slope's horizontal direction dynamic response plays an important role. At the same location on the slope surface, the relative horizontal acceleration of the slope increases with the incident angle of P-waves and SV-waves, and the maximum value on the back-slope side is approximately 19 times and 6.8 times that of the front-slope side, respectively. Slope angle significantly affects the back-slope side's dynamic response, showing an increase with increasing slope angle, while canyon width has a limited impact.