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The effect of negative excess pore-water pressure on the stability of excavated slopes

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Ghadrdan, M, Shaghaghi, T and Tolooiyan, A ORCID: 0000-0001-8072-636X 2020 , 'The effect of negative excess pore-water pressure on the stability of excavated slopes' , Géotechnique Letters, vol. 10, no. 1 , pp. 1-10 , doi: 10.1680/jgele.19.00040.

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Abstract

Generation of negative excess pore-water pressure (NEPWP) due to the excavation of saturated soils under undrained conditions and the dissipation that follows over time may result in different short- and long-term slope instability. The NEPWP generated due to excavation gradually decreases towards equilibrium or, in some cases, steady seepage. Hence, total pore-water pressures immediately after excavation are lower than the ultimate equilibrium values, leading to a reduction of the average effective stresses in the slope and subsequently threatening stability in the long term. In this research study, the stability of three benchmark civil and mining excavations has been studied, considering the effects of the generation and dissipation of NEPWP. A series of numerical simulations are conducted to determine the role of in situ stresses and time in NEPWP dissipation as well as the consequent effects on the stability of the excavated slopes. To conduct a realistic time-dependent transient analysis, fully coupled hydro-geomechanical formulation has been employed. Results show that in general, higher removal of stress levels lead to higher NEPWP generation and higher factor of safety values in the short term. Thereafter, the dissipation of NEPWP threatens the long-term stability of the excavation.

Item Type: Article
Authors/Creators:Ghadrdan, M and Shaghaghi, T and Tolooiyan, A
Keywords: excavation, pore pressures, time dependency
Journal or Publication Title: Géotechnique Letters
Publisher: ICE Publishing
ISSN: 2045-2543
DOI / ID Number: 10.1680/jgele.19.00040
Copyright Information:

Copyright 2019 ICE Publishing

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