A constitutive model considering the interaction between evolution of microstructure and hydro-mechanical behaviour of unsaturated soils

Wu, Tianchi, Cleall, Peter John ORCID: https://orcid.org/0000-0002-4005-5319 and Tripathy, Snehasis ORCID: https://orcid.org/0000-0003-1632-7668 2024. A constitutive model considering the interaction between evolution of microstructure and hydro-mechanical behaviour of unsaturated soils. Computers and Geotechnics 176 , 106775. 10.1016/j.compgeo.2024.106775

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Abstract

The evolution of microstructure induced by loading and unloading has a significant impact on the hydro-mechanical behaviour of soils, including volume change, shear strength, water retention and permeability. In this paper, a constitutive model based on the evolution of microstructure is established building on the approach of an existing mechanistic model. In this model, the evolution of microstructure is represented via changes in the pore size distribution (PSD) and assumed to be related solely to the change of void ratio induced by loading and unloading. A PSD-dependent Bishop’s effective stress coefficient χ*, which represents the coupled impact of PSD evolution on hydro-mechanical behaviour of soils, is used to replace the Bishop’s effective stress coefficient χ. The model can reproduce and predict the hydro-mechanical behaviour and evolution of microstructure and their interaction within a unified framework. It also has potential in studying the soil-water characteristic curve and multi-field-coupling of soils. Model response and sensitivity analysis are reported based on idealized parameters to give a primary evaluation on the model’s performance and feasibility of using PSDs from mercury intrusion porosimetry. It is found that whilst the model is sensitive to parameters representing inter-aggregate pore size distributions it can be satisfactorily applied to represent the hydro-mechanical behaviour and microstructural evolution of unsaturated soils.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Engineering
Publisher:	Elsevier
ISSN:	0266-352X
Date of First Compliant Deposit:	26 September 2024
Date of Acceptance:	15 September 2024
Last Modified:	26 Sep 2024 09:02
URI:	https://orca.cardiff.ac.uk/id/eprint/172358

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