Hydro-mechanical modelling of MX-80 bentonite: one dimensional study

Abstract

Abstract.As a first step towards modelling the coupled Thermo-Hydro-Mechanical-Chemical (THMC) behaviour of bentonite, the Barcelona Basic Model (BBM) has been implemented into Numerrinfinite element code. This model has beenfully coupled with the single phase flow equation for unsaturated soils which models liquid water transport. Suction obtained from solving the flow equation is used as an input for the BBM model and the volumetric deformations from the mechanical analysis are used to update the pore water pressure field. As an alternative, BBM is used alongside the Kröhn's model which assumes that bentonite re-saturation is mainly driven by water vapour diffusion. The paper simulates one dimensional infiltration test on MX-80bentonite with both implemented modelsfor water transport and compares the results withthose from a laboratory experiments based on X-ray tomography.The numerical results of the simulations are similar despite taking into account different physical phenomena.

A study on how to couple thermo-hydro-mechanical behaviour of unsaturated soils: Physical equations, numerical implementation and examples

“…The modification is introduced to account for the thermal effects and the dependency of the elastic parameters on suction and net stress. Both implicit [48][49][50] and explicit scheme with error control [51][52][53][54][55] could be used to integrate the constitutive stresses. In what follows, only the mathematical formulation of the constitutive model is presented whereas the numerical integration details are omitted due to space limitations.…”

“…The bentonite is modelled as a BBM material (see Section 2.3.1) with the calibrated mechanical properties given in Table 4. The parameters of MX80 are kept in the same range to that provided in literature [55,85,86]. Eq.…”

Applications of the new thermo-hydro-mechanical-chemical coupled code ‘Thebes’

“…Appendix A gives an introduction to the BBM framework, though the interested reader may like to check the full description of the model and the numerical implementation given in previous publications (e.g. Abed, 2008;Sołowski and Gallipoli, 2010;Sołowski et al, 2012;Sołowski and Sloan, 2013;Abed et al, 2016;Abed and Sołowski, 2017).…”

“…The developed framework encompasses novel features that include among others: 1) a more accurate derivation of the dry air and the thermal energy balance equations; 2) a new implementation of the temperature influence on the soil water characteristic curve and 3) effects of microstructure evolution on the water retention features and hydraulic conductivity of the simulated geomaterial. For the full discussion on these new developments, implementation, verification and validation of the code, the reader is referred to Abed et al(2016) and Abed andSołowski (2017, 2018). Recently, the capabilities of Thebes Code has been extended to include simple chemical effects based on the theoretical work of Warrick et al (1971), Van Genuchten (1982 and Boufadel et al (1997).…”