A hydrodynamic theory for clay
Applied Mechanics, Statics and Dynamics
Final Report Abstract
In this project, a new constitutive model for clays has been developed, diverging from traditional approaches to lay the foundation for a new theoretical framework for describing clay behavior. The development of the model was based on the hydrodynamic procedure, which, although admittedly unusual in soil mechanics, is physically rigorous and goes beyond solely satisfying the first two laws of thermodynamics. The key feature of the model is the separation of scales in the constitutive description of clay. For this purpose, an additional temperature, the meso-related temperature, was introduced as a new state variable to capture the fluctuations of clay aggregates and particles. This additional scale allows for a description of the energy decay as a two stage processes, where it either transfers directly to the micro-scale to increase the thermal temperature or dissipates initially to the meso-scale where it raises the newly introduced meso-related temperature before sinks to the micro-scale. The most significant advancement of the model is the development of a new strategy to identify the constitutive relations that describe the plastic flow (strain rate) using well-known empirical observations. This approach eliminates the need for classical constructs of mathematical plasticity, such as yield surfaces and plastic multipliers and results in a remarkably simple model. The model was validated with experiments from multiple datasets of different clays. Thanks to its rigorous formulation and despite its mathematical simplicity, the model is capable of capturing many complex behaviors of clays. Notably and thanks to the newly introduced meso-related temperature, it successfully describes a wide range of rate-dependent phenomena during transient loading, as well as creep and relaxation processes. Given the generality of hydrodynamics, it is anticipated that the new model could be expanded to capture various multi-physics phenomena.
Publications
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A novel hydrodynamic formulation for clay. Poster and booklet abstract at ALERT Geomaterials, 2024.
M. Wiebicke & I. Einav
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A novel perspective on clay modelling using hydrodynamic principles. Theme lecture at IS-Grenoble 2024 (International symposium under the under the auspices of Technical Committee 105 of the ISSMGE). Grenoble, France, 2024.
M. Wiebicke & I. Einav
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A simple hydrodynamic model for clay. Journal of the Mechanics and Physics of Solids, 192, 105789.
Wiebicke, Max & Einav, Itai
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A simple hydrodynamic model for clay. Presentation at the international workshop SANDLESS in Sydney, Australia, 2024.
M. Wiebicke & I. Einav.
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A unified perspective on rate and state, critical state, and thermodynamic state using hydrodynamics. Extended abstract and presentation at ICTAM (International congress of theoretical and applied mechanics). Daegu, South Korea, 2024.
Einav, M. Wiebicke, D. Riley, F. Masi & F. Guillard
