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Lookup NU author(s): Dr Bruna LopesORCiD
This is the authors' accepted manuscript of an article that has been published in its final definitive form by I C E Publishing, 2021.
For re-use rights please refer to the publisher's terms and conditions.
The paper presents an analysis of the long-term stability of a large unsupported cave excavated ingranular cohesionless material in Ficulle, Italy. The stability of the cave arises from a‘cohesive’term inthe shear strength criterion and this paper investigates the source of this cohesive term. Contrary toexpectations, the material appeared to be granular (cohesionless) at the touch. The investigation startedby determining whether the stability of the cave was attributable to any cementation bonding the soilparticles. Microstructural analyses, together with geomechanical testing, produced enough evidence tosuggest that the material was not naturally cemented. On the other hand, water-undrained direct sheartests on unsaturated intact specimens indicated the presence of significant apparent cohesion, whichwas then linked to the existence of suction in the material. In this way, the stability of the cave wasassessed accounting for the beneficial effects of suction and partial saturation on shear strength. Athree-dimensional analysis based on the upper bound theorem of plasticity was successful inconfirming the stability of the cave in terms of the state of the structure at the time of fieldinvestigation. In addition, it was shown that 24 and 48 h rainfalls of 100 years return period are notsufficient to relieve suction sufficiently to bring the cave to collapse, thus justifying the observed long-term stability of the cave. Suction is rarely included in geotechnical design under the assumption that itcannot be relied upon owing to the potentially adverse effect of rainwater infiltration. This case studydemonstrates that suction can indeed remain‘active’naturally for a long time, contributing to the long-term stability of geo-structures.
Author(s): Lopes BCFL, Tarantino A
Publication type: Article
Publication status: Published
Journal: Géotechnique
Year: 2021
Volume: 71
Issue: 12
Pages: 1085-1098
Print publication date: 01/12/2021
Online publication date: 14/12/2020
Acceptance date: 07/07/2020
Date deposited: 22/07/2022
ISSN (print): 0016-8505
ISSN (electronic): 1751-7656
Publisher: I C E Publishing
URL: https://doi.org/10.1680/jgeot.19.P.269
DOI: 10.1680/jgeot.19.P.269
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