Saturated hydraulic conductivity of problematic soils measured by a newly developed low-compliance triaxial permeameter

Abstract

Research on the reliable characterization of saturated permeability has received great yet necessary attention globally. However, most studies were carried out on soils with a volumetric tendency being almost insensitive to water saturation or at least with this hidden assumption. This is clearly not the case when dealing with the two broad categories of problematic soils, including collapsible and expansive soils. As confirmed by previous research, at least one-fifth of the planet comprises of these soils with a relatively fair distribution. Therefore, the main objective of this study is to introduce a low-compliance double cell/burette permeameter to track all volumetric changes during the whole pre- and post-saturation testing stages with distinct enhancement of accuracy. In order to examine the performance of the device, two typical types of collapsible and expansive soils are synthesized and tested for a wide variety of void ratios. Comparison of results with four standardized and conventional testing protocols in the literature reveals that current laboratory methods fail in reliable quantification of saturated permeability of problematic soils due to inaccurate evaluation of void ratio, imperfect saturation, or both. Eventually, a discussion will be presented on the performance of some empirical models in capturing the new experimental trends.