Calibration of Model Parameters for Soda Saline Soil-Subsoiling Component Interaction Based on DEM

To apply the discrete element method (DEM) to simulate the interaction process between soda saline-alkali soil and subsoiling component in Northeast China, establishing the soda saline-alkali soil particle model and selecting more accurate simulation parameters are important. In this paper, we studied the soda saline-alkali soil of the Songnen Plain in China. First, we studied the geometric shape of soda saline-alkali soil particles and proposed a modeling method for single soil particles based on the multisphere combination method. Considering the cohesion of soda saline-alkali soil particles, the Hertz-Mindlin with JKR (JKR) model was used as the contact model between soil particles. Then, the calibration method was used to obtain simulation parameters of soils that are difficult to obtain experimentally. We conducted soil angle of repose (AoR) tests, the Plackett-Burman (PB) tests, and steepest ascent (SA) tests in turn to perform a sensitivity analysis for microscopic contact parameters and select the parameters that have a significant effect on the response value (static AoR), i.e., soil surface energy, soil-soil static friction coefficient, and soil-soil rolling friction coefficient. Then, the optimal combination of simulation parameters was obtained via the Box-Behnken (BB) tests, using ANOVA to optimize the multiple regression equation. Finally, the optimal parameter combination was verified by the AoR test and the direct shear (DS) test. The results showed that the parameters had good adaptability for the AoR test. However, the simulation results of the DS test were significantly different from the experimental values. Therefore, the contact model needs to be further modified by adding Bonding bonds between soil particles based on the JKR model and further correcting for Rayleigh time step, shear modulus, and surface energy. By comparing the simulation and the experimental results, it was found that the simulation results obtained from both the DS test and AoR test had relatively small errors relative to physical tests, the two trends are the same, and the values are similar. This verified the feasibility and effectiveness of the soda saline-alkali soil particle modeling method and parameter selection proposed in this paper.