Capillary-induced tensile strength in unsaturated sands

Abstract

While a majority of the studies related to unsaturated soils have focused on volume change, flow, and shear strength behavior, investigations of tensile strength of unsaturated soils, especially granular soils, have not received much attention except for those on cemented and clayey soils. This paper focuses on fundamental studies of tensile strength properties of granular soils in the unsaturated state, which were examined experimentally and theoretically. Experimental studies have shown that it is possible to accurately measure the tensile strength of sands at water contents in the range of 0.5%–17% by means of simple techniques. The method of specimen preparation has proved important, and the use of relatively large specimens has made development of homogeneous specimens and measurements relatively straightforward. The magnitude of the tensile strength of moist and relatively clean sands varies with water content, density, and soil type. The experimental data are also compared with mechanics-based models developed for monosized spheres, and their application for a real granular soil with a variety of particles is discussed in the unsaturated state, which includes the pendular, funicular, and capillary regions.