Earthquake-induced Permanent Ground Deformation (PGD), occurring as a surface fault deformation, can significantly affect underground lifelines such as buried pipelines. To examine the performance of the buried pipelines against such ground movements, several methods emphasizing on steel pipes have been developed. In this study a new method which models the surrounding soil around the pipes to take into account the real soil-pipe interaction was developed. Finite element method was used to model soil-pipe system and explicit approach was also employed to solve the governing equations. The new developed method was used to asses the behavior of High Density Polyethylene (HDPE) pipelines subjected to the fault motion. Tow types of HDPE pipes, smooth and corrugated profiles were considered. The results show that the compressive displacements of fault affect buried smooth pipe profiles, however for buried corrugated polyethylene pipelines this effect is not pronounced. For smooth pipe profiles the best intersection angle of fault with the pipeline is about to reduce the internal strains. However this angle for the corrugated profile pipes was obtained around . The second part of this study focused on seismic response of buried pipelines subjected to Transient Ground Deformations (TGD). The results of analysis showed that there is a possibility of inducing some residual strains in the pipelines, however the amount of these strains are not comparable with the allowable strain.
