The Loess Plateau in China was highly susceptible to reactivation of old landslides due to rainfall and agricultural irrigation. Understanding the evolution and formation mechanisms of slope sliding zones was crucial for investigating large deformations associated with recurrent landslides. A comprehensive understanding of the mechanical behavior of sliding zone loess was therefore essential to elucidate landslide initiation mechanisms. To this end, this study focused on the sliding zone loess from a slope in Yangling and conducted ring shear tests based on the proposed concept of equivalent circumferential strain. The shear mechanical behavior of the loess was systematically investigated across the full deformation range—from small to large strains. Furthermore, the interactive effects of multiple factors on shear strength parameters were analyzed using Response Surface Methodology (RSM), and a predictive model for residual strength was established. The results indicated that: the water content w was negatively correlated with both the peak strength τmax and residual strength τr, while it was positively correlated with the peak strain γmax. The impact of compaction degree K on τr and γmax was minimal, whereas it exerted a significant influence on τmax, exhibiting a positive correlation with the latter. The compaction degree K only had an effect on τmax, but not as significant as w, and it was positively correlated with it. K had a small effect on τr and γmax. By using RSM, the effects of water content w, compaction degree K, and vertical stress p on the peak strength τmax and residual strength τr of the landslide loess were analyzed, and the main effects of each factor were p > w > K. When K interacted with other factors, its effect on the sample was easily overlooked. When K was large, the shear stress-equivalent circumferential strain curve (τ-γi) of loess in the slip zone usually showed softening. However, as both w and p increased, the influence of K gradually diminished, leading to a hardening trend in the curve. The above results will provide a scientific basis for identifying and restoring old landslides in the loess region of Northwest China.

Research on the mechanical properties and residual strength prediction model of an old loess landslide

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发表日期：

2026年3月6日

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Xican Cui,
Lingfeng Zhao,
Yasheng Luo,
Kaihao Zheng,
Chengbin Zhao

摘要

The Loess Plateau in China was highly susceptible to reactivation of old landslides due to rainfall and agricultural irrigation. Understanding the evolution and formation mechanisms of slope sliding zones was crucial for investigating large deformations associated with recurrent landslides. A comprehensive understanding of the mechanical behavior of sliding zone loess was therefore essential to elucidate landslide initiation mechanisms. To this end, this study focused on the sliding zone loess from a slope in Yangling and conducted ring shear tests based on the proposed concept of equivalent circumferential strain. The shear mechanical behavior of the loess was systematically investigated across the full deformation range—from small to large strains. Furthermore, the interactive effects of multiple factors on shear strength parameters were analyzed using Response Surface Methodology (RSM), and a predictive model for residual strength was established. The results indicated that: the water content w was negatively correlated with both the peak strength τ_max and residual strength τ_r, while it was positively correlated with the peak strain γ_max. The impact of compaction degree K on τ_r and γ_max was minimal, whereas it exerted a significant influence on τ_max, exhibiting a positive correlation with the latter. The compaction degree K only had an effect on τ_max, but not as significant as w, and it was positively correlated with it. K had a small effect on τ_r and γ_max. By using RSM, the effects of water content w, compaction degree K, and vertical stress p on the peak strength τ_max and residual strength τ_r of the landslide loess were analyzed, and the main effects of each factor were p > w > K. When K interacted with other factors, its effect on the sample was easily overlooked. When K was large, the shear stress-equivalent circumferential strain curve (τ-γ_i) of loess in the slip zone usually showed softening. However, as both w and p increased, the influence of K gradually diminished, leading to a hardening trend in the curve. The above results will provide a scientific basis for identifying and restoring old landslides in the loess region of Northwest China.