Determining parameters of a discrete element model for soil–tool interaction

The discrete element method (DEM) has been recognized as an effective tool to simulate soil–tool interactions. However, most existing discrete element models were for cohesionless soils, and in those models there were limited discussions on selections and calibrations of model parameters. In this study, a soil–tool interaction model was developed using a commercial DEM software, Particle Flow Code in Three Dimensions (PFC3D). In the model, soil particles were defined with the basic PFC3D model particles, which consisted of balls with cohesive bonds between balls. The model parameters, bond normal and shear strengths, were determined based on intrinsic stresses of soil. The most sensitive model parameter, ball normal stiffness, was calibrated for two contrast soils: coarse and fine soils. The calibrations were performed through comparing the draught forces of a simple soil engaging tool simulated with the PFC3D soil–tool interaction model and those estimated with the Universal Earthmoving Equation. The calibrated ball normal stiffness is 6 × 103 N m−1 for coarse soil and 2 × 104 N m−1 for fine soil.