Effect of initial void ratio on the tensile strength of unsaturated silty soils

The tensile strength of unsaturated soils is a fundamental property in various geotechnical designs. Reliable estimation of the tensile strength of unsaturated soils, in particular fine-grained soils, is required in both theoretical research and engineering practice. Although several tensile strength models have been proposed in the literature, an overestimation may occur over a wide suction range, when applying them in the modelling of tensile strength of fine-grained soils. In this paper, the tensile strength of an unsaturated lean clay has been measured over a wide range of void ratio and water content by employing the Brazilian tensile strength test. A critical degree of saturation can be observed for specimens with different void ratios, at which the soil tensile strength reaches the peak. In addition, a predictive tensile strength model considering the effect of initial void ratio has been subsequently proposed for both coarse-grained and fine-grained unsaturated soils based on the interaction mechanisms between the adsorptive and capillary soil water. Finally, the proposed model has been demonstrated to be capable of modelling the tensile strength characteristic curve of various soil types ranging from clean sands to silty and clayey soils.

Automated summary

The tensile strength of unsaturated soils, particularly fine-grained soils, is an important property in geotechnical designs. Current models for estimating tensile strength might overestimate for fine-grained soils. This study measured the tensile strength of unsaturated lean clay and proposed a predictive model based on the interaction mechanisms between soil water and initial void ratio, which can be used for both coarse-grained and fine-grained unsaturated soils.