# Research on Predicting the Mechanical Characteristics of Deep-Sea Mining Transportation Pipelines
## 3 Deep Sea Mining Pipeline Mechanical Simulation
### Orthogonal Experimental Design and Dynamic Simulation  
Due to the influence of various ocean environmental parameters on the deep-sea mining system, a large number of tests are required to comprehensively simulate the load-bearing conditions of the deep-sea mining conveyance pipeline under various working conditions. The orthogonal experimental design can effectively combine the levels of each parameter, providing a comprehensive assessment of the effects of different factor combinations, reducing the number of repetitive tests, and improving test efficiency. In this study, the orthogonal experimental design scheme was formulated using the SPSS statistical tool [6], combining the working conditions within the range of ocean environmental parameters introduced earlier, as shown in Table 6. The wind speed, wave period, and significant wave height were each set at intervals of 0.5. As the deep-sea mining conveyance pipeline operates at different depths, it is significantly influenced by variations in ocean current factors. Thus, the study considered multiple ocean current speeds in the region where the deep-sea mining operation is conducted, including one common condition and four recurrence period conditions. The ocean current angles were set to the most frequent levels, focusing on the main eight ocean current angles introduced earlier. The experiment included five factors: wind, waves, and currents. Each factor was assigned 5, 5, 6, 5, and 8 levels, respectively. Figure 9: Distribution of bending moment along the length of the flexible hose. If a full factorial experiment were conducted, it would require completing 6000 sets of experiments, necessitating extensive computational resources and time. By utilizing an orthogonal experimental design, an L\({}_{64}\) orthogonal array was selected to accommodate 5 factors and 8 levels as shown in Table 7, resulting in a total design of 64 combinations of working conditions. The ocean current speed is represented by the ratio of the surface current speed to the deep current speed. Through dynamic simulation calculations, the pipeline's mechanical response parameters were determined. The pipeline strain, effective tension, bending radius, and bending moment were selected as the outcomes of the orthogonal experiment. Obtaining a substantial amount of simulation sensor data through dynamic simulation is essential for constructing a predictive model of pipeline mechanical properties. The volume of data significantly impacts the model's prediction error, where algorithms trained on less data tend to have larger errors. Thus, based on experience, this study set tens of thousands of data sets for training the neural network model. Dynamic simulations were conducted for the 64 sets of working conditions derived from the orthogonal experiment, with each simulation set to 50 s and a time step of 0.1 s, resulting in 501 data points per simulation. Consequently, the experiment generated a total of 32,064 sets of simulation sensor data for training and testing the pipeline mechanical properties prediction model. Given the vast amount of data, this paper selects and displays part of the simulation time history data from the first set of experimental conditions for demonstration. When the wind speed is 2.5 m/s, the wave period is 10 s, the significant wave height is 1 m, and the surface current speed is 2 m/s, the time history data of mechanical parameters for both