## 1 Introduction  
The study on the dynamic response of large slopes plays a critical role in sustainable economic growth, public safety governance, and ecological environmental protection. Seismic landslides cause heavy casualties and economic losses as well as severe damage to the geo-environment. In areas with frequent earthquakes, each seismic event can increase the risk of damage [1]. The construction of large-scale infrastructure projects has resulted in a large number of mixed soil-rock slopes, and these projects cannot be without risk in a seismic zone. The stability of large-scale slopes during earthquakes has become a difficult problem in the engineering community [2]. The damage extreme earthquakes cause to engineering structures cannot be ignored. For instance, the depth of the soil cover has a significant impact on the response of bridges [3]. The dynamic response of seismic excitation plays a pivotal role in the assessment of the stability of large-scale slopes. In the existing studies, seismic loads are applied uniformly to the base of the slope as equivalent static forces in the horizontal and vertical directions. This approach, based on the plane wave assumption of Huygens' principle, allows for the study of quasi-static equilibrium using D'Alembert's principle, which introduces hypothetical inertial forces to the system of masses [4]. The results show that both slope geometry and rock material have great influence on the horizontal and vertical amplification factors [5; 6]. The wave field at the slope surface could be modified depending on the ratio between the slope height and the wavelength, which affects the distribution of the peak amplification near the slope crest [7]. The research methods based on uniform seismic loading provide a foundation for the application of plane wave assumptions in the geotechnical field of slope stability. However, the plane wave assumption does not apply to shallow earthquakes (<10 km), which are more often the result of dynamic triggering by Rayleigh-wave stresses [8]. Researchers have collected 214 seismic records in the western American region, and the statistical results show that the average value of the S wave incident angle is 56.78 degrees. Numerous studies and investigations have shown that the dynamic response of large-scale slopes is significantly affected by non-uniform earthquakes. In such cases, the uniformity of seismic waves, which are based on the plane wave assumption, is no longer applicable. From the perspective of the seismic ray theory, non-uniform seismic waves can be conceptualized as oblique incident waves originating from the hypocenter and propagating towards the site. Recent research has demonstrated that the dynamic response of oblique seismic waves at sites and structures cannot be overlooked in near-source earthquakes [9; 10]. Both the topography and stratigraphy of slopes significantly affect the ground motions of slopes during earthquakes, and the oblique incidence of seismic waves can further aggravate amplification [11]. The amplification of the peak ground acceleration (PGA) and spectral response acceleration (SRA) of rock slopes under obliquely incident seismic waves has been a topic of considerable interest within the academic community. The influence of the seismic wave incidence angle on the amplification effect of slope topography is significant and necessary [12; 13]. Some research results indicate that incident angles of seismic waves and slope angles change the propagation paths of seismic waves, and thus control the failure mode of the slope [14; 15]. For instance, the presence of hills clearly changes the spatial distribution of seismic motions. In the case of oblique incidence, seismic motions near the slope facing away from the source are much larger than those near a slope facing towards the source in a canyon [16]. The conventional Newmark approach neglects the phenomenon of seismic amplification in soil slopes, leading to potential inaccuracies in the assessment of seismic stability.