A Simplified Pipeline Strain Demand Model for Frost Heave

摘要

Structural analysis methods used in the design of buried pipelines forrnthe discontinuous permafrost regions need to handle the uniquernconditions that can arise; in particular thaw subsidence and frost heave.rnAs a chilled gas pipeline traverses from a frost stable soil zone to a frostrnsusceptible zone, frost bulbs are formed around the pipe and cause thernpipeline to heave. If there is significant differential heave, pipernbending across the interface between these two zones could result inrnpipe strains exceeding design limits, or in extreme cases, buckling orrntensile fracture.rnFor pipelines subjected to geotechnical hazards, characterization ofrnstrain demand is an integral part of the strain-based design process.rnThis paper describes a simplified finite element model that wasrndeveloped to predict compressive and tensile strain demand of gasrnpipelines subjected to frost heave. By using features that are typicallyrnavailable in general-purpose finite element analysis software, thernproposed pipe-soil interaction model addressed issues that are essentialrnfor predicting pipeline strain demand. These issues includernpressure-dependent heave displacement, and geometrically non-linearrnload-displacement response of steel pipe. The simplified model wasrnvalidated by comparing model predictions to the Caen tests.