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Forecasting the long-term deterioration of a cut slope in high-plasticity clay using a numerical model

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journal contribution
posted on 10.12.2020, 14:27 by Harry Postill, PR Helm, Neil DixonNeil Dixon, S Glendinning, JA Smethurst, M Rouainia, KM Briggs, Ashraf El-HamalawiAshraf El-Hamalawi, AP Blake
This paper details development of a numerical modelling approach that has been employed to forecast the longterm performance of a cut slope formed in high plasticity clay. It links hydrological and mechanical behaviour in a coupled saturated and unsaturated model. This is used to investigate the influence of combined dissipation of excavation-generated excess pore water pressures and seasonal weather-driven near-surface cyclic pore water pressures. Deterioration of slope performance is defined in terms of both slope deformations (i.e. service) and factor of safety against shear failure (i.e. safety). Uniquely, the modelling approach has been validated using 16 years of measured pore water pressure data from multiple locations in a London Clay cut slope. Slope deterioration was shown to be a function of both construction-induced pore water pressure dissipation and seasonal weather-driven pore water pressure cycles. These lead to both transient and permanent changes in factor of safety due to effective stress variation and mobilisation of post-peak strength reduction over time, respectively, ultimately causing shallow first-time progressive failure. It is demonstrated that this long-term (90 year) deterioration in slope performance is governed by the hydrological processes in the weathered near surface soil zone that forms following slope excavation.

Funding

ISMART

Engineering and Physical Sciences Research Council

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Assessment, Costing and enHancement of long lIfe, Long Linear assEtS (ACHILLES)

Engineering and Physical Sciences Research Council

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History

School

  • Architecture, Building and Civil Engineering

Published in

Engineering Geology

Volume

280

Publisher

Elsevier BV

Version

VoR (Version of Record)

Rights holder

© The authors

Publisher statement

This is an Open Access Article. It is published by Elsevier under the Creative Commons Attribution 4.0 Unported Licence (CC BY). Full details of this licence are available at: http://creativecommons.org/licenses/by/4.0/

Acceptance date

05/11/2020

Publication date

2020-11-16

Copyright date

2020

ISSN

0013-7952

Language

en

Depositor

Prof Neil Dixon Deposit date: 9 December 2020

Article number

105912