Modeling and measurements of triaxial tests for a sandy loam soil

Abstract

The knowledge and understanding of soil mechanical properties is essential for designing agricultural machines. However, little information is available regarding shear properties of agricultural soil. In this study, triaxial compression tests were performed to measure shear properties of a sandy loam soil at three moisture levels: low (10.5±0.5%), medium (19±1.0%), and high (28±1.0%), and three confining pressures of 50, 100, and 150 kPa. A discrete element model was developed to simulate the triaxial compression tests. The test results showed a linear increase in soil shear strength at a decreased soil moisture level and an increased confining pressure. The effect of moisture level on the modulus of elasticity changed with the confining pressure. The highest modulus of elasticity was observed for the low moisture level with 150 kPa confining pressure. The model results showed that the particle friction coefficient was the most influential model micro-parameter to the simulated soil shear strength. This model micro-parameter was calibrated with the triaxial test data. The calibrated particle friction coefficients varied from 0.2 to 1.0, depending on the soil moisture content and confining pressure. As compared to the test data, the simulated soil shear strengths had relative errors ranging from 0 to 6%.