Rate-dependency of residual shear strength of soils: implications for landslide evolution

0572535 - ÚSMH 2024 RIV GB eng J - Journal Article
Duque, J. - Loche, Marco - Scaringi, G.
Rate-dependency of residual shear strength of soils: implications for landslide evolution.
Geotechnique Letters. Roč. 13, č. 2 (2023), s. 105-112. ISSN 2049-825X. E-ISSN 2045-2543
R&D Projects: GA TA ČR(CZ) SS02030023
Institutional support: RVO:67985891
Keywords : landslide * residual shear strength * shear-rate effect * velocity strengthening * velocity weakening
OECD category: Environmental and geological engineering, geotechnics
Impact factor: 2.1, year: 2022
Method of publishing: Limited access
https://doi.org/10.1680/jgele.23.00004

Shear-rate weakening or strengthening behaviours can effectively control landslide runouts, defining sudden runaway sliding or years-long slow-creep phases. These behaviours are partly controlled by the properties of the basal material. Understanding its stress-strain-time response is crucial in physically-based assessments of landslide dynamics and the associated risk. We investigate the frictional resistance of a calcium bentonite, a kaolin and a quartz sand by means of a conventional ring-shear apparatus under normal stresses representative of landslide shear zones. Results for the fine-grained soils, in line with literature on pure clays, indicate important velocity strengthening, whereas small shear-rate effects were observed in sand. As long as effective stresses remain constant, a velocity strengthening response can exert a feedback that, under certain conditions, counteracts perturbations in boundary conditions and prevents fast runouts on pre-existing shear zones. Accordingly, we argue that specifically testing for shear-rate-dependency and incorporating observed behaviours in model formulations can be beneficial for better predicting landslide fates.
Permanent Link: https://hdl.handle.net/11104/0345874