Calibration of discrete element parameters and experimental verification for modelling subsurface soils

The discrete element method (DEM) has shown considerable advantages for the simulation of soil-tool interaction simulation. To develop reliable DEM simulations, the selection of an appropriate contact model and its parameter calibration are critical. A DEM model of cohesive subsurface soils was established to predict the draught of sweep cultivation by using the Edinburgh elasto-plastic adhesion (EEPA) contact model. Firstly, the DEM parameters were used for calibration, which were significant for the results of the uniaxial confined compression test and the unconfined compressive strength test. Then, the mapping relationship between other DEM parameters and the soil stress–strain behaviour was calculated to obtain a solution matching the stress–strain measurement results. Finally, cone penetration resistance (penetration rate of 8 mm s−1) and the draught of sweep tillage (depth of 200 mm and speed of 1.67 m s−1) were used to evaluate the accuracy of the parameters. The results showed that the penetration resistance in the elastic phase of the simulation was in close agreement (R2 = 0.9964) with the measurements, and the total relative error and the average relative error between the predicted sweep draft and the measurement were 9.4% and 4.77%, respectively. Thus, it was shown that the developed calibration method can effectively predict the development of the sweeping draught and the penetration stress.