Modelling the time-dependent mechanical behaviour of clay rocks based on meso- and micro-structural viscous properties

Modelling the time-dependent mechanical behaviour of clay rocks based on meso- and micro-structural viscous properties

Sun, Yufeng (Université de Lyon)
Pardoen, Benoît (Université de Lyon)
van den Eijnden, A.P. (TU Delft Geo-engineering)
Wong, Henry (Université de Lyon)

2023

Clay rocks are multiphase porous media having a complex structure and behaviour characterised by heterogeneity, damage and viscosity, existing on a wide range of scales. The mesoscopic scale of mineral inclusions embedded in a clay matrix has an important role in the mechanisms of deformation under mechanical loading by cracking and creeping. This study introduces a micromechanical approach to model the time-dependent mechanical behaviour of clay rocks. A heterogeneous clay rock is represented at the mesoscopic scale as a composite material consisting of rigid elastic mineral inclusions (quartz, calcite and pyrite) embedded in a clay matrix. To describe the damageable rock behaviour and its failure modes at the small scale, interfaces between different mineral phases and within the clay matrix are considered. Viscous effects are incorporated inside the clay aggregates, with intergranular microfractures propagating in the clay matrix, in order to investigate their contribution to the creep behaviour of clay rock at the macroscale. The mesostructure of the clay rock is represented in digital 2D Representative Elementary Areas (REAs). The overall mesoscale behaviour of the clay rock under mechanical solicitation is numerically obtained from the REA by computational homogenisation within a two-scale finite element squared framework. Then, the model is validated at mesoscale against experimental data. The variability of the material response and the time evolution of the mineral interfacial damage state are investigated in relation to the small-scale properties and failure, while considering mesostructure variability. The results can give some valuable insights into creep behaviour of the clay rock from a small-scale perspective.

clay rock
creep
microstructural variability
multiscale numerical model
viscosity

http://resolver.tudelft.nl/uuid:22a430ac-c946-42ee-8446-4098b4f0c337

https://doi.org/10.1002/nag.3617

2024-03-07

0363-9061

International Journal for Numerical and Analytical Methods in Geomechanics, 47 (17), 3177-3208

Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.

Institutional Repository

journal article

© 2023 Yufeng Sun, Benoît Pardoen, A.P. van den Eijnden, Henry Wong