Modelling the evolution of dual-pore structure for compacted clays along hydro-mechanical paths

Abstract

The evolution of dual-pore structure for compacted clays along hydro-mechanical paths exerts considerable influences on their phenomenological behavioral properties. This study aims to propose a novel approach for modelling the evolution of dual-pore structure. Here bimodal pore size density (PSD) function is considered to be obtained by superposing two unimodal lognormal distribution functions, which are inter-aggregate PSD (inter-PSD) and intra-aggregate PSD (intra-PSD). Unimodal PSD at arbitrary state is assumed to be obtained from initial one through shifting, scaling and spreading. On the basis, six evolution parameters are defined with unambiguous physical meanings. The modelling approach for evolving bimodal PSD is proposed through relating these evolution parameters to inter-aggregate and intra-aggregate void ratios respectively, where inter-aggregate and intra-aggregate void ratios are determined based on an empirical relationship between intra-aggregate void ratio and water ratio. The empirical parameter calibration in this approach is specific to stress paths. The proposed approach is applied to model the dual-pore structure evolution for compacted clays along loading path, wetting and drying paths under free condition, as well as wetting path under isochoric condition. Comparisons between the predicted and measured data show the novel approach can effectively capture the evolution of dual-pore structure along various hydro-mechanical paths.