Coupled analysis of soil shear strength and retention curves with different interstitial fluids

Soil shear strength is a fundamental property in analyzing the stability of soil masses in many Geotechnical applications, such as slope stability, foundations, and retaining structures. Routinely application considers water as the interstitial fluid composing the soil, however, in some instance other liquids than water can infiltrate the ground due to accidental leakages of fuel and chemical substances. This paper evaluates the influence of fluids of different nature (water, ethanol, and diesel) on the shear strength of compacted specimens of clayey soil, both under saturated and unsaturated conditions. Test results show that the shear strength increases with suction and decreases with the dielectric constant for all the tested liquids. Based on simplified experimental procedures, two coupled models are proposed to reproduce the influence of soil suction and fluid dielectric constant on the soil shear strength and soil liquid retention curve, fairly reproducing experimental results, thus contributing to push unsaturated soil mechanics to Geotechnical practice.