Modeling the behavior of natural gas pipeline impacted by falling objects

A numerical approach, based on the finite-element method was established in this paper to simulate impact behavior of buried gas pipeline. A three-dimensional elastic perfectly plastic soil model with plane strain conditions was employed in this analysis. The influence of relative stiffness of pipeline–soil, buried depth of pipeline and impact energy on the stress distribution of buried pipelines was discussed. The analysis results showed that the maximum pipeline stress decreased with the increase of the relative stiffness of pipeline–soil; however, the penetration depth was independent of the relative stiffness of pipeline–soil. Pipeline stress decreased with the increase of buried depths and began to stabilize when the buried depth was more than 3 m. The results of impact load and penetration depth considering the plasticity of soil were much larger than those not considering it. To minimize the discrepancy of results between the current approaches and the actual situation, a new method was put forward to improve the accuracy of the proposed formula computing impact load and penetration depth. The results from the new theoretical method were closer to those from the finite element analysis and tests.