An experimental and constitutive investigation on the chemo-mechanical behaviour of a clay

Abstract

An experimental and constitutive investigation on the chemo-mechanical behaviour of a clay P. WITTEVEEN Ã , A. F ERRARI Ã a nd L. LALOU I Ã Engineering issues for which the understanding of the chemo-mechanical behaviour of soils is relevant include wellbore stability problems, the salinification of groundwater, and nuclear waste storage. However, despite the vast number of situations in which couplings between chemistry and mechanics occur, the available constitutive models rely on limited experimental evidence. This paper presents the results of an experimental programme on the chemo-mechanical behaviour of a non-swelling illite. The osmotic suction is controlled through the ion concentration of sodium chloride in the pore water. Stress paths include mechanical loading at a constant osmotic suction, and an increasing osmotic suction at a constant mechanical stress. The experimental results point out a correlation between the osmotic suction and initial oedometric modulus, as well as between the osmotic suction and yield stress. A constitutive framework for soils is extended to take the observed chemo-mechanical couplings into account. The numerical model has been calibrated for the illite using the parameters obtained through the tests under mechanical loading at a constant concentration, and validated using more elaborate stress paths. The presented experimental and constitutive investigation builds a basis for the assessment of engineering issues in which pore liquid chemistry plays a major role.

Characterization and constitutive modeling of red clay contaminated with ammonium carbonate

“…Methods are also developed to calibrate the model parameters by direct use of the results from oedometer and direct shear tests. The capability of the proposed model to simulate the chemomechanical coupled behavior is verified by considering the experimental results reported by Witteveen et al 23 . Comparisons are made between the measured and predicted results from which the advantages of the proposed model are demonstrated.…”

“…In other words, any foundation design without considering the effect of urea will be risky from the geotechnical point of view. In addition, all previously mentioned constitutive models 23,27–30 were developed for the specific soils of interest and could not be used for red clays contaminated with urea, which had significantly different properties.…”

“…Therefore, due to the conversion of large areas of previously agricultural red clay into domestic and industrial construction sites accompanied by the rapid urbanization in southern China and lack of considerable research in this area, there is a great need to better understand the influence of urea on the engineering behavior of red clays. Clayey soils treated with chemicals frequently exhibit irrecoverable volume change when subjected to mechanical loading and/or changes in salt concentrations 2,21–24 . Therefore, elastoplastic constitutive frameworks should be used to simulate their behavior.…”

“…A double‐structured model was developed based on the Barcelona basic model (BBM) to consider the osmotic suction, which represents chemical effects, for unsaturated soils 31 . Recently, based on the framework of Hujeux model, 32 Witteveen et al 23 extended the advanced constitutive model for environmental geomechanics (ACMEG) for unsaturated soils 33 to account for the coupled chemomechanical elastoplastic behavior of clayey soils. However, all these constitutive models were developed for the specific soils of interest.…”

A Theoretical Framework for Modeling the Chemomechanical Behavior of Unsaturated Soils

“…Earlier research and practices were mainly concerned with reactive flow and transport, and numerous flow and transport models have been developed, without addressing mechanical issues (e.g., Spycher and Sonnenthal, 2003; Steefel et al, 2005; Xu and Pruess, 2001). With regard to the chemomechanical behavior of porous media, a few research studies have been performed with a focus on the chemoplasticity of fully saturated soils (e.g., Hueckel, 2002; Loret et al, 2004; Witteveen et al, 2013). In addition, the cross‐scale effect and multiprocesses coupling of multiphase systems has been an active field of research on experimental, theoretical, and numerical bases (e.g., Di Maio et al, 2002; Coussy, 2010).…”