## 3 Results and Analysis
### Analysis of the Two-Level Factorial Test Results  
Through the two-level factorial test, significant influencing factors on the maximum shear force were identified. Then, simulation experiments were conducted in the EDEM software, the results of which are shown in Table 4. A significance analysis was then performed in the Design-Expert software, with the results presented in Table 5.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \
\begin{tabular}{c} **Serial** \\ **Numbers** \\ \end{tabular} & \(x_{1}\)**/mm** & \(x_{2}\)**/(\(\times\)10\({}^{8}\) N\(\cdot\)m\({}^{-3}\))** & \(x_{3}\)**/(\(\times\)10\({}^{8}\) N\(\cdot\)m\({}^{-3}\))** & \(x_{4}\)**/(\(\times\)10\({}^{6}\) Pa)** & \(x_{5}\)**/(\(\times\)10\({}^{6}\) Pa)** & \(x_{6}\)**/mm** &
\begin{tabular}{c} **Maximum Shear** \\ **Force/N** \\ \end{tabular} \\ \hline
1 & 1.6 & 1 & 1 & 5 & 5 & 1.4 & 43.1 \\
2 & 1.4 & 0.5 & 1 & 5 & 5 & 1.4 & 29.4 \\
3 & 1.4 & 1 & 0.5 & 5 & 5 & 1.4 & 29.8 \\
4 & 1.6 & 1 & 0.5 & 10 & 10 & 1.6 & 40 \\
5 & 1.4 & 1 & 0.5 & 10 & 10 & 1.6 & 40 \\
6 & 1.4 & 1 & 1 & 10 & 10 & 1.6 & 64.8 \\
7 & 1.6 & 1 & 1 & 10 & 10 & 1.6 & 64.8 \\
8 & 1.6 & 0.5 & 0.5 & 10 & 10 & 1.6 & 27.1 \\
9 & 1.6 & 0.5 & 0.5 & 5 & 5 & 1.4 & 22.9 \\
10 & 1.6 & 1 & 0.5 & 5 & 5 & 1.4 & 29.8 \\
11 & 1.6 & 0.5 & 1 & 10 & 10 & 1.6 & 37.9 \\
12 & 1.4 & 0.5 & 0.5 & 10 & 10 & 1.6 & 27.1 \\
13 & 1.6 & 0.5 & 1 & 5 & 5 & 1.4 & 29.4 \\
14 & 1.4 & 1 & 1 & 5 & 5 & 1.4 & 43.1 \\
15 & 1.4 & 0.5 & 0.5 & 5 & 5 & 1.4 & 22.9 \\
16 & 1.4 & 0.5 & 1 & 10 & 10 & 1.6 & 37.9 \\ \hline \hline \end{tabular} Note: \(x_{1}\) is the particle contact radius, \(x_{2}\) is the normal stiffness per unit area, \(x_{3}\) is the tangential stiffness per unit area, \(x_{4}\) is the critical normal stress, \(x_{3}\) is the critical tangential stress, and \(x_{6}\) is the bonding radius.  
\end{table}
Table 4: Design and results of two-level factorial tests.  
Figure 9: Results of single-factor experiments. Note: \(x_{1}\) is the particle contact radius, \(x_{2}\) is the normal stiffness per unit area, \(x_{3}\) is the tangential stiffness per unit area, \(x_{4}\) is the critical normal stress, \(x_{5}\) is the critical tangential stress, and \(x_{6}\) is the bonding radius.  
As shown in Table 5, the \(p\)-value of this model is less than 0.0001, indicating that it is highly statistically significant and, thus, both reliable and well-fitted. The coefficient of determination (R\({}^{2}\) = 0.9285) is close to 1, which suggests a strong correlation between the model and the data. The adjusted R\({}_{\rm add}^{2}\) = 0.8809 further confirms the precision and reliability of the two-level factorial test results. Specifically, the \(p\)-values for factors \(x_{2}\) and \(x_{3}\), which are both less than 0.001, indicate that these factors have a highly significant effect. \(x_{6}\) had a \(p\)-value less than 0.1, which suggests a statistically significant effect. In contrast, \(x_{1}\), \(x_{4}\), and \(x_{5}\) were not significant influencing factors influencing shear force. As illustrated in Figure 10, the Pareto chart confirms the significance of \(x_{2}\), \(x_{3}\), and \(x_{6}\), as their effects exceed the critical t-value threshold, further supporting their classification as significant influencing factors.