ASSESSMENT OF POLYETHYLENEPIPELINESUNDER LANDSLIDE

With increasing global demands for energy resources, pipeline systems, called as lifelines, play a significant role in urban processes. For safety considerations pipeline systems in urban areas buried in soil. Therefore, landslide is one of general problems in water conducting pipelines which occurred increasingly within last decade. During landslide, excessive plastic deformations occur in pipeline which lead to local plastic failures in critical parts of pipeline system. In case of landslide it is important to avoid crossing slopes but in practice because of environmental restrictions it can’t be avoided. Generally geotechnical processes, such as landslide, are so complicated so many researches have been focused on landslide and its effects on lifeline systems. This paper has been focused on failure in polyethylene buried pipelines under non-uniform deformations of landslide. Within design process of pipelines, critical problem is to determine allowable strain and stress limits in pipeline under landslide. Here a finite element model of polyethylene pipeline has been prepared in ABAQUS software with a contact element to model interaction of soil and pipeline. Final model include soil profile and pipeline system crosses perpendicular to landslide direction. In this paper variation of surrounding soil and geometry of pipeline have been investigated. This paper tries to investigate failure potential of pipeline under excessive deformations and variation of these parameters. A failure criterion has been proposed based on strain limits of pipeline. Finally failure potential have been assessed by means of fragility curves. Given results in this paper could be used in practical design codes of water conducting pipeline systems.