## 1 Introduction  
Mixed rock and soil deposits mainly stem from landslide accumulation, residual accumulation, alluvial accumulation, etc., and are distributed widely as large-scale slopes in Sichuan Province, China [1, 2]. Deposit collapse and landslides account for a significant proportion of the disasters caused by the Wenchuan earthquake [3, 4, 5]. Theoretical analysis and research have shown that the surface amplification effect of a seismic slope is closely related to the impedance difference and wave velocity difference of near-surface geo-materials [6, 7, 8], such as the overlaying deposit (filling layer, colluvium layer, alluvium layer, etc.) on the bedrock, and the strong weathering layer covering the weak weathering layer, etc. [9, 10, 11]. Deposit slopes with underlying bedrock are prone to secondary disasters, such as dammed lakes and mudslides. In recent years, the construction of large-scale water conservancy projects, hydropower projects, and transportation hubs in south-western China has been undertaken, and the risk of huge loss of life and property caused by earthquakes is increasing. Stabilizing piles are one of the most widely used engineering structures in landslide management because of their small disturbance of the surrounding geological environment, good support effect, and ease of construction [12, 13, 14, 15]. On the other hand, the disaster investigation teams deployed after the Wenchuan earthquake found that stabilizing piles generally had a good anti-seismic effect, but there are also a large number of stabilizing piles that had overturned and even cracked and been broken [16]. This suggests that the current understanding of the anti-seismic mechanism of stabilizing piles is not yet clear: design and theory lack practical application and remain to be explored. To understand the seismic strengthening mechanism of slope-stabilizing piles, it is necessary to clarify the dynamic responses of slopes under seismic action, the distribution of the stabilizing pile bending moment, and the distribution of earth pressures thereon. At present, the research methods deployed include on-site monitoring [17; 18; 19; 20] and model testing [21; 22; 23; 24; 25; 26]. In recent years, more numerical simulation data have been made available from studies of slopes reinforced by stabilizing piles. The software FLAC is used by [PERSON] et al. [27] to perform the analyses of the effective working conditions of the soil arching effect between the stabilizing piles and the influence of stabilizing piles on the safety factor of the slope. [PERSON] and [PERSON] [28] adopt the three-dimensional finite difference numerical simulation method to study the influence of multiple excitation directions of seismic waves on the lateral displacements of a sand slope reinforced by a row of floating piles. The simulation results show that, compared with the unreinforced sandy slope, the insertion of a row of stabilizing piles (at a pile spacing some 2.5 times the pile diameter) reduces the slope lateral displacement by more than 50%. [PERSON] et al. [29] conducted a slope stability analysis of a slope-pile system by numerical simulations. The results show that the coupling analysis method can better reflect the pile-soil interaction, which is more consistent with reality. The boundary conditions of the pile head and the bending stiffness of the pile exert a considerable influence on the stability safety factor of the slope. Using a numerical simulation analysis, [PERSON] et al. [30] proposed a method for determining the yield acceleration of a slope reinforced with a row of drilled shafts under seismic load. [PERSON] et al. [31; 32] studied the response characteristics of an embedded single pile used to reinforce an unstable mass through a 3D finite difference numerical analysis. The numerical results show that the strength parameters of the slip interface have a significant influence on the behavior of the pile. However, most of these studies are focused on the behavior of homogeneous slopes reinforced by stabilizing piles.