# Research on Predicting the Mechanical Characteristics of Deep-Sea Mining Transportation Pipelines
## 3 Deep Sea Mining Pipeline Mechanical Simulation
### Deep-Sea Mining Conveyance Pipeline Static Simulation  
The effective tension along the length of the lifting hard pipe, as obtained from static analysis, is illustrated in Figure 6. The maximum effective tension occurs at the top of the hard pipe, with a maximum value of 1509.38 kN, which is less than the maximum allowable tension of 10,000 kN for the lifting hard pipe. The effective tension the lifting hard pipe experiences decreases gradually along its length. Due to the top end of the hard pipe being hinged to the mining vessel, the positions of the hard pipe closer to the top are more significantly affected by the heave motion of the mining vessel and wave forces. The effective tension along the length of the flexible hose is shown in Figure 7. At 0 m and 300 m lengths of the hose, it is connected to the mining vehicle and the intermediate storage, respectively. Between the positions of 100 m-150 m along the hose, the effective tension is less than at the two peak points. This reduction in tension is due to the placement of buoyancy bodies within this interval, which decreases the effective tension exerted on the pipeline under the influence of buoyancy. The maximum effective tension distributed along the length of the hose is 26.87 kN, occurring at 107.5 m, which is less than the maximum allowable tension of 200 kN for the flexible hose. The distribution of the bending radius along the length of the flexible hose is shown in Figure 8. The minimum bending radius value distributed along the hose length is 5.13 m, located at 132.5 m of the hose, which is greater than the minimum allowable bending radius of 1 m for the flexible hose. Figure 5: Top view of deep-sea mining system and ocean current direction. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Water Depth (m)**} & \multicolumn{4}{c}{**Ocean Current Speed (m/s)**} \\ \cline{2-5}  & **1-Year Return** & **10-Year Return** & **50-Year Return** & **100-Year Return** \\ \hline
0.00 & 0.86 & 0.95 & 1.01 & 1.03 \\
30.38 & 0.82 & 0.91 & 0.97 & 0.99 \\
299.80 & 0.61 & 0.66 & 0.69 & 0.71 \\
499.59 & 0.39 & 0.41 & 0.42 & 0.42 \\
699.50 & 0.38 & 0.39 & 0.40 & 0.41 \\
899.28 & 0.36 & 0.38 & 0.39 & 0.39 \\
1099.07 & 0.36 & 0.37 & 0.38 & 0.39 \\
1298.98 & 0.35 & 0.37 & 0.38 & 0.38 \\
1498.77 & 0.35 & 0.37 & 0.38 & 0.38 \\
1698.67 & 0.35 & 0.37 & 0.38 & 0.38 \\
1712.50 & 0.23 & 0.25 & 0.26 & 0.26 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Ocean current speeds for various return periods. The bending moment is a parameter related to the characteristics of the bending radius. By ensuring that the minimum value of the bending radius distributed along the hose  
Figure 8: Distribution of bending radius along the length of the flexible hose. Figure 6: Distribution of effective tension along the length of the lifting hard pipe. Figure 7: Distribution of effective tension along the length of the flexible hose. length falls within the normal working requirements and conducting a static analysis of the bending moment, a more comprehensive study of the mechanical properties of the deep-sea mining conveyance pipeline can be achieved. As shown in Figure 9, the maximum value of the bending moment distributed along the hose length is 2.66 kNm, located at 132.5 m of the hose. The position of the minimum value of the bending radius along the hose length is also the position with the maximum value of the bending moment distributed along the hose length. From the static analysis, it is known that when the deep-sea mining conveyance pipeline is in static equilibrium, both the maximum effective tension distributed along the pipeline and the minimum value of the bending radius distributed along the hose fall within the design performance requirements of the pipeline. The characteristics of the bending moment are closely related to the bending radius.