Abstract
Experimental observations of the erosion of clays indicate a high degree of coupling between the hydro-chemical processes in the clay–water system and the mechanics of erosion. In contrast with the volume of experimental work and the significance of swelling clay erosion in many geotechnical engineering problems, limited advances have been made with the predictive modelling of this phenomenon. The critical erosion step, missing in existing models, is the particles’ detachment from the moving boundary of the expanding clay – a discontinuous process. This paper presents, for the first time, a non-local formulation for clay erosion, which brings together clay swelling, particle detachment and detached particle transport, into a single modelling tool. The detachment criterion, an essential element of the integrated erosion model, is first tested against a series of experimental benchmarks to show the excellent agreement between calculated and experimental results. The integrated erosion model is subsequently validated by comparison with experimental data for the behaviour of compacted bentonite under several eroding environments. The results: (a) show clearly the capacity of the model to capture concurrently the free swelling of clay, the detachment of clay particles and the transport of detached particles in the eroding environment; and (b) support strongly the applicability of the model to account for the hydro-chemical conditions (composition and velocity) of the eroding environment. The proposed multi-physics non-local formulation, successfully validated for hydro-chemical effects on clay erosion, provides a robust framework for incorporating a wide set of additional couplings.
Highlights
Robust prediction of clay erosion is important for a range of geotechnical engineering problems: from clay erosion in embankments (Fujisawa et al, 2009), through erosion of clay in the geological disposal of nuclear waste (Schatz et al, 2013), to erosion of geosynthetic clay liners (Ashe et al, 2014)
Of particular importance and recent interest is the erosion of clay buffer and backfill in the context of geological disposal of high-level nuclear waste (HLW)
The full erosion model was applied to cases with available experimental data for erosion of compacted bentonite under three hydro-chemical conditions
Summary
Robust prediction of clay erosion is important for a range of geotechnical engineering problems: from clay erosion in embankments (Fujisawa et al, 2009), through erosion of clay in the geological disposal of nuclear waste (Schatz et al, 2013), to erosion of geosynthetic clay liners (Ashe et al, 2014). Of particular importance and recent interest is the erosion of clay buffer and backfill in the context of geological disposal of high-level nuclear waste (HLW). During the long-term operation of disposal facilities, the clay buffer/backfill can be subject to erosion induced by the hydro-chemical interactions at the interface between the clay and the fractured host rock. The aim of this paper is to address the need for a realistic and robust modelling of clay erosion. This is accomplished by presenting a set of new formulations, based on the non-local continuum mechanics
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