Dynamic response analysis of buried pipelines under rockfall impact

In view of the rockfall impact threat faced by buried pipelines in high-risk areas of geological disasters, in order to further explore its dynamic response characteristics, this paper systematically studied the dynamic response characteristics of buried pipelines through the combination of scale model test and numerical simulation. Its purpose is to dig deep into these characteristics. During the experiment, this study, firstly, constructed a test model at a geometric scale ratio of 1:10. And at the same time, a drop hammer impact test device combined with LS-DYNA finite element analysis was used. Based on these above, the influence laws of pipe burial depth, wall thickness, impact parameters, pipe parameters, and soil properties (including soil elastic modulus and pipe-soil friction coefficient) on buried pipelines were explored. The test results show that at the same impact height, the peak strain decreases as the pipeline’s burial depth and wall thickness increase. When facing the eccentric drop hammer impacts, the influence on the upper and lower cross-sections of the pipeline diminishes as the impact point deviates from the pipeline center. Additionally, a higher impact height corresponds to a greater peak strain in the middle section of the pipeline.The numerical simulation results indicate that the maximum stress and strain of the pipeline are positively correlated with pipeline diameter, internal pressure, and impact velocity, while negatively correlated with impact eccentricity, soil elastic modulus, and pipeline burial depth. Moreover, the increase in the pipe-soil friction coefficient has a limited impact on pipeline stress and strain, and this effect becomes negligible when it exceeds 0.3.Based on Pearson correlation analysis, the order of influence degree of each parameter is impact eccentricity first, then pipeline internal pressure, then pipeline diameter, then soil elastic modulus, then pipe-soil friction coefficient last. Among them, pipeline internal pressure, pipeline diameter, and pipe-soil friction coefficient are positively correlated with strain, while soil elastic modulus and impact eccentricity are negatively correlated with strain. The rockfall impact eccentricity and pipeline internal pressure have a moderate to strong correlation with the impact on buried pipelines.The research results can provide a basis for the safety design of buried pipelines in high-risk areas.