Anomalous shear stress variation in wet granular medium: Implications for landslide lateral faults

Geophysical Research Letters
By: , and 

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Abstract

Landslide assessments typically focus on the mechanical properties of the basal shear zone, but lateral faults are frequently overlooked, possibly due to their lower normal stresses and variably saturated conditions. Using double-cylinder shear experiments on wet granular systems as analogs for landslide lateral faults, we observe anomalous shear stress variations with fluid volume fractions, defying an expected unimodal relationship associated with capillary cohesion. At low fluid volume fractions, shear strength weakens as the wet grain assembly experiences reduced lateral pressure and increased boundary slip. This boundary slip subsequently vanishes, with an abrupt strengthening due to the dilation of the grain assembly against fluid surface tension as saturation approaches. Strike-slip motion and confinement in this system explain the strength anomaly, highlighting a critical role of lateral faults in landslide stability, particularly in cases where dynamics cannot be adequately explained by monitored pore-water pressure or basal friction.

Publication type Article
Publication Subtype Journal Article
Title Anomalous shear stress variation in wet granular medium: Implications for landslide lateral faults
Series title Geophysical Research Letters
DOI 10.1029/2024GL113816
Volume 52
Issue 7
Publication Date April 04, 2025
Year Published 2025
Language English
Publisher American Geophysical Union
Contributing office(s) Geologic Hazards Science Center - Landslides / Earthquake Geology
Description e2024GL113816, 11 p.
Additional publication details