# Study on the Macro-Fine Mechanical Behavior of Ore Flow Based on the Discrete Element Method
## 3 Construction of the Numerical Model
### Establishment of the Numerical Model  
According to the geometric parameters of the ore pass in situ, as shown in Section 2.2 in this paper, when the numerical model is established, the center of the drawing port is considered as the coordinate origin, and the total height of the ore storage section and the ore-drawing funnel is 38.4 m, as shown in Figure 4a. In order to monitor the lateral pressure of the ore-pass wall, 9 monitoring points, numbered 1-9 from bottom to top, are arranged along the left shaft wall at 4 m intervals. For observing the flow state of the ore-rock bulk, the ore-rock particles with different colors are placed in layers every 4 m upward from the lower to upper in the ore storage section, there are seven layers.  
For analyzing the micromechanical changes during the ore-rock bulk flowing in the ore pass, the ore-rock stress is monitored by the method of measuring the circle [28; 29]. A total of 18 columns and 53 measurement circles are arranged in the storage section of the ore-pass from bottom to top. Columns 1 to 6 are called Group 1; 7 to 12 are named Group 2; and 13 to 18 are named Group 3. The radius of each measurement circle is set to 1 m. By using surfer software, the coordination number and internal stress recorded via the measurement circle were used to draw the stress distribution cloud map in the Y-direction, so as to quantitatively characterize the micromechanical change characteristics of the stored ore-rock bulk. By using surfer software, the coordination number and internal stress recorded by the measurement circle were used to draw the stress distribution cloud map in the Y-direction so as to quantitatively characterize the micromechanical change characteristics of the stored ore-rock bulk, as shown in Figure 4b.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Types**} & **Normal Stiffness/(N/m)** & **Tangential Stiffness/(N/m)** & **Ore-Rock Bulk Density/(kg/m\({}^{3}\))** & **Friction Coefficient** & **Anti-Rotation Friction Coefficient** & **Particle Size/m Particles/N** \\ \hline Ore particles & 3.33 \(\times\) 10\({}^{9}\) & 3.33 \(\times\) 10\({}^{9}\) & 2050 & 0.7 & 0.7 & 0.1–0.6 & 13,468 \\ Wall & 3.33 \(\times\) 10\({}^{9}\) & 3.33 \(\times\) 10\({}^{9}\) & — & 0.65 & — & — & — \\ \hline \hline \end{tabular}
\end{table}
Table 2: Mesoscopic parameters of the numerical model.  
Figure 3: Discrete element collapsed measurement model with the particle size in a range of 0.1 m\(\sim\)0.6 m.  
It should be noted that during the physical experiment, the geometric size of the ore pass and the size of the ore-rock particles in the case mine were scaled according to the ratio of 1:20. However, in numerical analysis, these were modeled according to the actual size of the mine, which is very different from the method proposed by [PERSON], [PERSON] and [PERSON] et al. [30; 31; 32]. The authors' intention is to verify the consistency of the results of different methods and to conform to the actual situation of the ore pass in the case mine.