# Calibration of Model Parameters for Soda Saline Soil-Subsoiling Component Interaction Based on DEM
## 3 Results and Discussion
### Calibration Results of the DEM Parameters of the Soda Saline-Alkali Soil  
Table 2 shows the PB design and results. The ANOVA (shown in Appendix A, Table A1) showed that the model was significant (\(p\)-value < 0.05), and the parameter \(I\) (soil surface energy) had the most significant effect on the static angle of repose. After that, the parameters that had a great influence on the static angle of repose were \(D\) (soil-soil static friction coefficient), \(E\) (soil-soil rolling friction coefficient), \(A\) (Poisson's ratio), \(F\) (soil-65 Mn steel restitution coefficient), \(B\) (shear modulus), and \(C\) (soil-soil restitution coefficient). After that, the SA test was carried out on \(I\) (soil surface energy), \(D\) (soil-soil static friction coefficient), and \(E\) (soil-soil rolling friction coefficient) to narrow the range of parameters with significant influence. The remaining parameters with less influence were taken as the intermediate value of the PB test. \begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline
**No.** & \(A\) & \(B\) & \(C\) & \(D\) & \(E\) & \(F\) & \(G\) & \(H\) & \(I\) & **Repose Angle \#(\({}^{\circ}\))** \\ \hline
1 & 1 & 1 & \(-\)1 & 1 & 1 & 1 & \(-\)1 & \(-\)1 & \(-\)1 & 38.66 \\
2 & \(-\)1 & 1 & 1 & \(-\)1 & 1 & 1 & 1 & \(-\)1 & \(-\)1 & 44.42 \\
3 & 1 & \(-\)1 & 1 & 1 & \(-\)1 & 1 & 1 & 1 & \(-\)1 & 31.47 \\
4 & \(-\)1 & 1 & \(-\)1 & 1 & 1 & \(-\)1 & 1 & 1 & 1 & 47.98 \\
5 & \(-\)1 & \(-\)1 & 1 & \(-\)1 & 1 & 1 & \(-\)1 & 1 & 1 & 49.72 \\
6 & \(-\)1 & \(-\)1 & \(-\)1 & 1 & \(-\)1 & 1 & 1 & \(-\)1 & 1 & 44.48 \\
7 & 1 & \(-\)1 & \(-\)1 & \(-\)1 & 1 & \(-\)1 & 1 & 1 & \(-\)1 & 37.95 \\
8 & 1 & 1 & \(-\)1 & \(-\)1 & \(-\)1 & 1 & \(-\)1 & 1 & 1 & 48.24 \\
9 & 1 & 1 & 1 & \(-\)1 & \(-\)1 & \(-\)1 & 1 & \(-\)1 & 1 & 42.65 \\
10 & \(-\)1 & 1 & 1 & 1 & \(-\)1 & \(-\)1 & \(-\)1 & 1 & \(-\)1 & 34.64 \\
11 & 1 & \(-\)1 & 1 & 1 & 1 & \(-\)1 & \(-\)1 & \(-\)1 & 1 & 41.35 \\
12 & \(-\)1 & \(-\)1 & \(-\)1 & \(-\)1 & \(-\)1 & \(-\)1 & \(-\)1 & \(-\)1 & 37.77 \\
13 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 45.76 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: PB test design and results. Figure 11: Density of soda saline-alkali soil under different plow layers. Figure 12: Variation of soda saline-alkali soil firmness under different tillage depths. The results of the SA test are shown in Table 3. At the level of the No. 3 test, when \(D\) was 0.6, \(E\) was 0.2, and \(I\) was 0.55, the static angle of repose was 44.44\({}^{\circ}\)\(\pm\) 0.82, the static angle of repose of the physical test was 44.32\({}^{\circ}\)\(\pm\) 2.001, and the minimum relative error was 0.28%. The No. 3 test level was used as the central point in the subsequent experiments, and No. 2 and No. 3 were used as low and high levels for the experimental design. Finally, we conducted the BB test. The test parameter level is shown in Table 4, the test design and results are shown in Table 5, and the nonsignificant parameters are the same as the SA test. From the BB test ANOVA (shown in Appendix A, Table A2), we can see that \(D\) (soil-soil static friction coefficient), \(E\) (soil-soil rolling friction coefficient), and \(I\) (soil surface energy) have significant effects on the static angle of repose. The parameters \(D\) (soil-soil static friction coefficient) and \(I\) (soil surface energy) have more significant effects on the static angle of repose than \(E\) (soil-soil rolling friction coefficient). Additionally, from the relationship curve between the experimental values and the predicted values of the fitted model (Figure 13), it can be seen that the data points are distributed around the fitted line with small errors, indicating that the model fits well and can be used for a predictive analysis of the static rest angle.