## 4 Results and Discussion
### Simulation of Different Construction Methods
#### 4.1.2 Construction Impact Stress Analysis  
In order to analyze the stress response characteristics of the model after pile excavation, the X-direction stress and Z-direction stress generated in regard to the pipeline by the traditional percussive drilling pile excavation method and the rotary drilling method are simulated and analyzed, respectively. The X-direction and Z-direction stress maps of the pipeline for the two construction methods are shown in Figures 11 and 12, respectively. From Figures 11 and 12, it can be seen that the maximum stresses in the horizontal direction caused by the conventional percussive drilling pile foundation construction and rotary drilling pile foundation construction at the monitoring point are 8.9 MPa and 1.39 MPa, with a stress increment of 7.51 MPa, and in the vertical direction, 2.64 MPa and 0.28 MPa, with a displacement increment of 2.36 MPa. Similarly, the simulation is  
Figure 11: (**a**) Z-direction stress cloud of oil pipeline for rotary drilling method; (**b**) Z-direction stress cloud of oil pipeline for traditional percussion drilling method. Figure 12: (**a**) X-direction stress monitoring at monitoring points for rotary drilling method; (**b**) X-direction stress monitoring at monitoring points for traditional percussion drilling method. Figure 10: (**a**) Z-direction displacement monitoring map of monitoring points for rotary drilling method; (**b**) Z-direction displacement monitoring map of monitoring points for traditional percussion drilling method. performed again after the application of monitoring points. The stress monitoring diagrams in the X and Z directions at the monitoring points for the two construction methods are shown in Figure 13 and Figure 14, respectively. From Figures 13 and 14, the maximum stresses in the horizontal direction caused by the traditional percussive drilling pile foundation construction and rotary drilling pile foundation construction at the monitoring point are 5.5 MPa and 1.3 MPa, with a stress increment of 4.2 MPa, and the maximum stresses in the vertical direction are 3.74 MPa and 2.64 MPa, with a stress increment of 1.1 MPa. It is basically in line with the results from the simulated cloud diagrams. Shear stress is the transverse cutting force generated within a material or structure, and it is very important for bridge pile construction adjacent to oil pipelines [27], as it directly affects soil stability, structural stability and the safety of the construction process. Therefore, shear stresses must be carefully considered and managed during bridge pile construction to ensure the reliability and safety of the pipeline system. It is worth noting that there is also a more significant difference between the shear stresses caused by the two construction methods on the pipeline, as shown in Figure 15.  
From the analysis shown in Figure 15, it can be seen that the maximum shear stress caused by the traditional percussion drilling method of digging holes reaches 15 MPa, which has exceeded the permissible pressure (10 MPa) for the design of the pipeline of Guangxi Oil Transmission Department 2 of the South China Branch of the National Pipe Network Company. When oil transmission pipelines are subjected to a large amount of shear stresses, it may lead to the deformation of the pipeline material, which depends on the elasticity modulus and shear modulus of the material. In some areas of the pipeline, such as welded joints or bends, shear stresses may lead to stress concentrations [28], increasing the risk of fatigue or damage in these areas. If the shear stresses exceed the shear strength  
Figure 14: (**a**) Z-direction stress monitoring at monitoring points for rotary drilling method; (**b**) Z-direction stress monitoring at monitoring points for traditional percussion drilling method. Figure 13: (**a**) X-direction stress cloud of oil pipeline for rotary drilling method; (**b**) X-direction stress cloud of oil pipeline for traditional percussion drilling method.