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, this study systematically investigated the dynamic response characteristics of buried pipelines through a combination of scale model test and numerical simulation to further explore its dynamic response characteristics and dig deep into their intrinsic mechanisms. A test model with a geometric scale ratio of 1∶10 was constructed. Meanwhile, a drop hammer impact test device combined with LS-DYNA finite element analysis was used. Based on these above, the influence laws of pipeline burial depth, wall thickness, impact parameters, pipeline 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. Under 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, pipeline internal pressure, pipeline diameter, soil elastic modulus, and pipe-soil friction coefficient. 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 response of buried pipelines.The research results can provide a basis for the safety design of buried pipelines in high-risk areas.