Evaluating Effect of Grain Composition and Moisture Content on the Shear Strength of Sand-Clay Mixture

The soil shear strength is one of the crucial parameters in the calculation of geotechnical problems such as slope stability analysis, pressure on retaining walls, etc. Investigation of the correlation among factors affecting shear strength helps to improve knowledge about the properties of the shear strength of the soil. In this study, experiments were conducted to clear up the influence of grain composition and moisture content on the soil shear strength. A series of direct shear tests were conducted on samples that were prepared with various sand-clay (bentonite) ratios and various moisture content. The results showed that shear strength decreased when the clay ratio was increased from 20% and the moisture content was increased from 15%. With clay ratios of less than 20% and moisture content of less than 15%, the shear strength is mostly less affected by grain composition and moisture content.