# Calibration of Model Parameters for Soda Saline Soil-Subsoiling Component Interaction Based on DEM
## 4 Conclusions  
This study utilized DEM to model saline soil particles with a multisphere combination approach and validated the model's accuracy using soda saline soil from Northeast China's Songnen Plain. We introduced a modeling method for individual soil particles based on their geometric shape. The effectiveness of this method was confirmed through comparisons between simulation results and experimental data from the angle of repose (AoR) and direct shear tests. 1. The physical properties of the soil, including the texture, density, water content, and particle size distribution, were tested. According to the test analysis, the soil studied in this paper is sandy loam. 2. Most soil particles can be approximated as spheres, ellipsoids, and cones. Based on the above three shapes, the geometric model of soil particles was established using the method of multisphere combination. Considering the adhesion between soil particles, the JKR model was used to calculate the force between particles. 3. The simulation parameters were calibrated by the soil AoR test. The results of the PB test showed that the static friction coefficient, rolling friction coefficient, and JKR surface energy between saline-alkali soil particles in Northeast China significantly affected the static angle of repose. Then, SA and BB tests were carried out to further determine the optimal parameter combination for soda saline-alkali soil simulation in Northeast China. ANOVA was used to analyze the BB test results, a quadratic regression model was established, and the model fit was good. The results showed that the soil-soil static friction coefficient, rolling friction coefficient, and JKR surface energy and parameters significantly affected the resting angle by a two-two interaction. 4. Sensitivity parameters were refined using a combination of the JKR and HMB contact models. The modified contact parameters are as follows: JKR surface energy is \(0.33\,\mathrm{J}/\mathrm{m}^{2}\), soil-soil static friction coefficient is \(0.734\), and soil-soil rolling friction coefficient is \(0.151\). The bonding parameters are as follows: normal stiffness per unit area is \(1\,\times\,10^{5}\)\(\mathrm{N}/\mathrm{m}^{3}\), shear stiffness per unit area is \(1\,\times\,10^{5}\)\(\mathrm{N}/\mathrm{m}^{3}\), critical normal stress is \(8\,\times\,10^{3}\)\(\mathrm{Pa}\), and critical shear stress is \(8\,\times\,10^{3}\)\(\mathrm{Pa}\). Using the modifiedparameter combinations for simulation and comparison with the physical tests, the simulation results closely matched the trend and values of the shear strength curve obtained in physical testing. The static repose angle obtained by simulation is 44.2\({}^{\circ}\), and the standard deviation is 1.405\({}^{\circ}\); it is not significantly different from the static AoR of the physical test, which is 44.32\({}^{\circ}\), and the standard deviation is 2.001\({}^{\circ}\). Thus, the reliability and accuracy of the obtained parameter combination were verified. The seven authors developed the research approach together. [PERSON], conceptualization and writing--original draft; [PERSON], writing--review and editing; [PERSON], formal analysis; writing--review and editing; [PERSON], formal analysis; writing--review and editing; [PERSON], formal analysis; writing--review and editing; [PERSON], formal analysis; writing--review and editing; [PERSON], formal analysis; writing--review and editing. All authors have read and agreed to the published version of the manuscript. This research was funded by [Science and Technology Research Project of Jilin Provincial Department of Education], grant number [JJKH20210339 KJ], and [Development of supporting equipment for ecological improvement of soda saline-alkali land in Northeast China], grant number [20210202018 NC]. All data analyzed during this study are included in this article. In this paper, we received technical support from the College of biological and agricultural engineering in Jilin University, including the Licensed software of EDEM and the coupling interface.