Influence of stress and water content on air permeability of intact loess

Abstract

Air permeability is one of the key parameters in performing consolidation analysis of unsaturated soil. Few data are available regarding the air permeability for intact loess under different applied stresses. The work reported in this paper evaluated the air permeability at isotropic stress using data obtained from laboratory investigations for intact loess. Air permeability tests were performed on specimens of intact loess at various water contents and isotropic stresses. Stress remarkably affected air permeability as a function of both liquid saturation and volumetric air content. There were all unique relationships not only between relative air permeability and liquid saturation as well as relative volumetric air content, but also between air permeability and modified air saturation for different stresses. The relative air permeability against liquid saturation could be well described by the Parker–van Genuchten–Mulaem (P-vG-M) model in terms of total liquid saturation. The relationship between relative air permeability and relative volumetric air content could be more conveniently expressed by the reference point power law (RPL) model, using the reference point values at natural water content rather than that at air-dried water content. Compared with the other two models, the proposed modified air saturation power law (MAPL) model was more appropriate to predict the air permeability.