# Numerical Simulation of Oil Pipeline Leakage Diffusion in Dashagou Yellow River Crossing Section
## 4 Results and Discussion  
### Resistance Coefficient Analysis  
The Miller soil box [33] was employed as the measuring instrument to ascertain the resistance coefficient of the soil samples gathered from the Dashagou region in the field in accordance with the Wenner device. The measuring devices are shown in Figure 14.  
It was utilized as the background parameter to simulate the leakage in the Dashagou section, with the objective of obtaining a leakage flow pattern that is more consistent with the actual conditions. This was performed with the objective of obtaining a leakage flow pattern that more closely aligns with the actual conditions. Combined with the fact that most of the buried depth of the pipeline in the crossing section is located in the layer of pulverized sandy soil (sandy chalky soil), the leakage simulations in the Dashagou section are calculated by the resistance coefficient value of pulverized sandy soil (sandy chalky soil), which is assumed to be the soil of the Dashagou section. Therefore, the simulation of the leakage in the Dashagou section is calculated using the value of the resistance coefficient assuming that the soil is sandy sand (sandy chalk). The flow pattern views of the leakage for 30 s, 15 min, 30 min and 1 h under different conditions are shown in Figures 15-17.  
Figure 14: Schematic diagram of Miller soil box measuring device (A,B are the supply electrodes and M,N are the measuring electrodes).  
Figure 13: Simulation flow chart.  
According to the leakage simulation results, the leakage flux is about 0.05 kg/s for a leakage opening radius of 10 mm, 0.13-0.15 kg/s for a leakage opening radius of 20 mm and 0.6-0.62 kg/s for a leakage opening radius of 50 mm, which indicates that the leakage flux is smaller and the leakage time is longer in powdery sandy soil/sandy silt, and the corresponding leakage risk and emergency window time are relatively small. The risk and emergency window time are relatively small.  
Under the same radius of the leakage opening, the overall effect of the location of the leakage opening on the leakage flux is not significant. For the same leakage pressure, the size of the leakage port has a more significant effect on the leakage volume. The crossing section of the pipeline in the study area is in a sandy chalky soil (chalky sandy soil) environment, where the oil leakage is subjected to stronger resistance and a smaller range of influence, which indicates that for the examination of the oil leakage flow process in the  
Figure 16: Schematic diagram of leakage flow mode comparison of side leakage ports under different leakage port sizes and different leakage duration.  
Figure 15: Schematic diagram of leakage flow pattern comparison at the bottom leakage port under different leakage port sizes and different leakage duration.  
porous media system, the influence of the soil lithological properties on the distribution of the fluids is crucial: usually the finer the particles, the higher the resistance, the stronger the oil leakage pressure can be attenuated and the smaller the distance and range of diffusion.