Numerical Investigation on Dynamic Response Characteristics and Deformation Mechanism of a Bedded Rock Mass Slope Subject to Earthquake Excitation  
[PERSON]  
1 State Key Laboratory of Hydroscience and Engineering, Department of Hydraulic Engineering,  
Tsinghua University, Beijing 100084, China; songdq2019@mail. Bedded rock slopes are the common type of geologic body in the southwest of China, whose dynamic stability greatly affects the surrounding infrastructure [15; 16]. Under the long-term geological action, a large number of discontinuous joints are generated in rock mass [17; 18; 19]. The failure modes of bedded slopes containing discontinuities are as shown in Figure 1, including sliding-tension failure, sliding-shear failure, bending-tension failure, and sliding-bending failure [20; 21]. Weak structural planes have an important influence on the dynamic characteristics and deformation and failure modes of rock slopes [22; 23; 24]. Due to the discontinuity of the structural planes in the rock mass, the interaction mechanism between the structural planes and seismic waves becomes very complex, thus making it difficult to fully understand the seismic response characteristics and failure modes of the rock slope [25; 26]. Hence, the seismic stability of bedded slopes has become very complicated, and thus, focused research should be conducted on the seismic failure mode of bedded slopes. Generally, the seismic acceleration of the time history of slopes provides the basic information to evaluate their dynamic response [27; 28]. The time-domain analysis can directly reflect the dynamic response law of a slope from the perspective of mechanics and deformation. The PGA is readily available and can be used to easily and efficiently analyze the changes in the amplification effect of slopes under earthquake excitation [28; 29]. The existing research about the seismic response of rock slopes mostly use the time-domain analysis [22; 23; 24]. Many scholars have used PGA to study the seismic response of different types of rock slopes, such as bedded slope, anti-dip slope, slope with multiple lithologic combinations, slope with discontinuous joints, etc. [13; 14; 15; 16; 17; 26]. It is worth noting that the existence of discontinuity in rock mass directly impacts the dynamic mechanics of slopes [30]; in particular, weak structural planes can result in the great change of frequency components of seismic waves in rock masses. However, the time-domain analysis using dynamic acceleration response cannot fully reflect the dynamic response characteristics of complex geological rock slopes [31; 32]. In addition, the dynamic response of slope is the result of the interaction of different frequency components of seismic waves. The frequency domain analysis can study the influence of ground motion parameters, topography, and geological conditions on the dynamic response law of slope from the perspective of the frequency domain. Previous studies have shown that frequency domain analysis can reveal the relationship between the superior frequency of the seismic wave, the natural frequency of rock slope, and its dynamic response characteristics from a deep level [31; 32]. At present, slope instability caused by the resonance between the superior frequency of the seismic wave and the natural frequency of rock and soil mass is, and has always been, a hot issue in the field of  
Figure 1: Typical failure mode of bedded rock slopes (Wang 2010): (**a**) sliding–tension failure, (**b**) sliding–shear failure, (**c**) bending–tension failure, (**d**) sliding–bending failure. seismic engineering [33]. In addition, as an important part of frequency-domain analysis, modal analysis is mainly used to obtain the vibration mode and natural frequency of the engineering entity, which can effectively reflect the relationship between the natural frequency of the engineering entity and its deformation response characteristics [34; 35; 36]. However, modal analysis has not been widely used in geotechnical engineering.