Buried pipelines running through areas of large differential ground movements, such as active landslides, can be subject to severe overstress conditions. Moving these pipelines to the surface (i.e. surfacing) and resting them on timber skids reduces the impact of ground movements because slippage can occur between the pipe and the skids. This approach has been used successfully on several pipelines. Surfacing was recently considered for a 4.5 km section of a buried pipeline situated in northern British Columbia. The surfaced pipeline is supported by timber skids every 2 m and winds through mountainous terrain containing twenty different movement zones in which differential displacements range from 0 m to 3 m. Along the route, the direction of the ground movement varied with the terrain. The alignment also crossed a creek with a 45 m clear span. This paper describes the methodology used in completing the stress analysis for the surfaced pipeline. To capture various load effects, an existing construction stage analysis program was modified to facilitate the modelling of the surface pipeline under the various load paths. The evolution of the displacement and stress state of the pipeline was determined and tracked for several different load paths. For each state, a single plot that summarized the ground movement, slip distances, skid reactions and pipe stresses was produced. The results from this analysis are used to discuss the response of surface pipelines under thermal and ground movement loads.

This content is only available via PDF.
You do not currently have access to this content.