Undrained Triaxial and Direct Shear Behavior of Loamy Soil: an Experimental Study

Loamy soils, characterized by a balanced mixture of sand, silt, and clay, offer high agricultural productivity and geotechnical applications. These soils exhibit medium water infiltration, aeration, and erosion, with high moisture and nutrient retention. They are less prone to flooding and disintegration compared to more clayey or sandy soils, owing to their balanced texture and optimal moisture retention. The effective stress principle, established by Terzaghi, explains the soil's behavior under different drainage conditions, with loamy soils showing moderate firmness when dry and cohesive properties when wet. This research aims to study the shear strength of loamy soils. CIU triaxial tests provided friction angles (ϕ') between 30° and 32° and cohesions (C') of 16 to 18 kPa, while direct shear tests yielded friction angles of 24.3° to 26.7° and cohesions of 22.7 to 36.1 kPa. Geotechnical characterization identified the soil as Silty Loam with high plasticity, containing kaolinite, quartz, and smectite. Overall, loamy soils exhibit complex behavior influenced by their texture, moisture, and compaction conditions, with significant implications for geotechnical applications and soil stabilization practices.