Beam Mode Buckling of Buried Pipeline Subjected to Seismic Ground Motion

Abstract

During seismic events, buried pipelines are subjected to deformation by seismic ground motion. In such cases, it is important to ensure the integrity of the pipeline. Both beammode and shellmode buckling may occur in the event of compressive loading induced by seismic ground motion. In this study, the beammode buckling of a buried pipeline that occurred after the 2007 Niigataken Chuetsuoki earthquake in Japan is investigated. A simple formula for estimating the critical buckling strain, which is the strain at the peak load, is derived, and the formula is validated by finiteelement analysis. In the formula, the critical buckling strain increases with the pipeline diameter and hardness of the surrounding soil. By comparing the critical strain derived in this study for beammode buckling with the critical strain derived in a past study for shellmode buckling, the formula facilitates the selection of the mode to be considered for evaluating the earthquake resistance of a pipeline. In addition to the critical buckling strain, a method to estimate the deformation caused by seismic ground motion is proposed; the method can be used to evaluate the earthquake resistance of buried pipelines. This method uses finiteelement analyses, and the soil–pipe interaction is considered. This method is used to reproduce the actual beammode buckling observed after the Niigataken Chuetsuoki earthquake, and the earthquake resistance of a buried pipeline with general properties is evaluated as an example.