Performance of parallel double pipelines under non-uniform seismic excitation

This paper investigates the structural safety of parallel double-buried pipelines under non-uniform seismic excitation considering the soil-pipeline interaction. A three-dimensional nonlinear numerical model has been established to study the effects of seismic wave propagation and ground motion intensity, as well as the pipeline internal pressure and spacing between the pipelines on their structural safety. The dynamic response of the parallel double buried pipelines was evaluated in terms of the acceleration amplification, settlement of ground surface, and strain, displacement, and elliptical deformation of the pipeline. The results demonstrate that the seismic response of buried pipelines under non-uniform excitation has obvious nonlinear characteristics, especially when the loading intensity is high. It is found that the internal pressure has virtually no effect on the site acceleration response, but it amplifies the settlement of the ground surface. Meawhile, it inhibits the elliptic deformation of the pipeline. Furthermore, the variation of the elliptic deformation of parallel buried pipelines is found to be the same for different pipeline spacings considered in this study. On the other hand, the pipelines spacing has a significant influence on their seismic response as the interaction between the two pipelines gradually decreases with the increase in the spacing.