Analysis of the Dynamic Reaction and Instability Deformation Differences of Loess Slopes with Different Landforms

Loess slopes such as loess ridges, mounds, and gully terrains are ubiquitous on the Loess Plateau, where these localized irregular topographies cause amplification and attenuation of seismic motions, thereby affecting the stabilization of slopes. On the basis of loess topography and geomorphology of the Xi Hai Gu region (Xiji, Haiyuan, and Guyuan) and indoor experiments,by establishing a three-dimensional numerical model of loess beam and loess Hill slope, the difference of ground motion response and deformation of loess slopes in different landforms is analyzed.The study revealed the following findings: 1. The PGA of the two slope generalization models has the largest amplification factor at the top of the slope, and the smallest amplification factor near the loess-mudstone contact surface. 2. Under identical seismic loading, the dynamic reaction of the loess mound slope was more pronounced than that of the loess ridge slope. Under varying seismic loading conditions, the PGA amplification factor of the loess mound slope exhibited greater variability. 3. The Fourier spectrum amplitude of the loess mound slope was greater than that of the loess ridge slope, with different predominant frequencies observed at the slope middle section for the two slope types. 4. Under the action of ground motion, both slope models experience instability and failure. The maximum movement of the loess mound slope is larger than that of the loess ridge slope. The maximum shear strain increment of the loess ridge slope takes place at the crown of the slope, while the maximum shear strain increment of the loess mound slope takes place at the slope shoulder. The research results have certain value for those engaged in the study of loess seismic landslides.