Alberti Stefano, Leshchinsky Ben, Roering Josh, Perkins Jonathan, Olsen Michael J
Department of Forest Engineering, Resources and Management, Oregon State University, Corvallis, OR, 97331, USA.
Department of Earth Sciences, University of Oregon, Eugene, OR, 97403, USA.
Nat Commun. 2022 Oct 13;13(1):6049. doi: 10.1038/s41467-022-33798-5.
Distributions of landslide size are hypothesized to reflect hillslope strength, and consequently weathering patterns. However, the association of weathering and critical zone architecture with mechanical strength properties of parent rock and soil are poorly-constrained. Here we use three-dimensional stability to analyze 7330 landslides in western Oregon to infer combinations of strength - friction angles and cohesion - through analysis of both failed and reconstructed landslide terrain. Under a range of conditions, our results demonstrate that the failure envelope that relates shear strength and normal stress in landslide terrain is nonlinear owing to an exchange in strength with landslide thickness. Despite the variability in material strength at large scales, the observed gradient in proportional cohesive strength with landslide thickness may serve as a proxy for subsurface weathering. We posit that the observed relationships between strength and landslide thickness are associated with the coalescence of zones of low shear strength driven by fractures and weathering, which constitutes a first-order control on the mechanical behavior of underlying soil and rock mass.
滑坡规模的分布被假定为反映山坡强度，进而反映风化模式。然而，风化和临界带结构与母岩和土壤力学强度特性之间的关联却缺乏明确的界定。在此，我们利用三维稳定性分析俄勒冈州西部的7330处滑坡，通过对已发生滑坡和重建滑坡地形的分析，推断强度（摩擦角）和黏聚力的组合。在一系列条件下，我们的结果表明，由于滑坡厚度与强度的交换，滑坡地形中剪切强度与法向应力相关的破坏包络线是非线性的。尽管大尺度上材料强度存在变异性，但观测到的比例黏聚强度随滑坡厚度的梯度变化可作为地下风化的一个指标。我们认为，观测到的强度与滑坡厚度之间的关系与由断裂和风化驱动的低剪切强度带的合并有关，这构成了对下伏土壤和岩体力学行为的一级控制。
