Effect of soil particle size on soil-subsoiler interactions using the discrete element method simulations

The discrete element method (DEM) has been widely used as a modelling tool to investigate soil-tool interactions. Soil particle size has an important effect on soil disturbance behaviours and cutting forces in discrete element models. In this study, discrete element models were developed using the EDEM software and evaluated using laboratory tests to investigate the effect of varying modelled particle radii (ranging from 3 to 19 mm) on soilsubsoiler interactions in the models. Soil disturbance characteristics (soil rupture distance ratio, height of accumulated soil, soil disturbance area, soil density change rate, and fragmentation index), solution time of the computer, and soil cutting forces (draft and vertical) were measured. Based on the ANOVA outputs, all these variables were significantly affected by the treatments at p < 0.05, except for the height of accumulated soil. Reducing particle radius from 5 mm to 3 mm gave an approximately sevenfold increase in solution time (about 500 h). For the soil used in the tests, 7 mm radii particles are recommended as the best choice for the Hertz-Mindlin with bonding (HMB) model, as indicated by low relative errors between simulated and experimental data of soil disturbance and cutting forces. The particle size should be taken into account in the calibration of the discrete element model to accurately predict both soil cutting forces and data of soil disturbance. The present study provides critical information for the selecting soil particle size in DEM models. (C) 2019 IAgrE. Published by Elsevier Ltd. All rights reserved.