Seismic Vulnerability Assessment and Retrofit of a Major Natural Gas Pipeline System: A Case History

The performance of pipeline systems during earthquakes is a critical consideration in seismically active areas. Unique approaches to quantitative estimation of regional seismic vulnerability were developed for a seismic vulnerability assessment and upgrading program of a 500‐km‐long natural gas pipeline system in British Columbia, Canada. Liquefaction‐induced lateral spreading was characterized in a probabilistic manner and generic pipeline configurations were modeled using finite elements. These approaches, developed during the early part of this 10‐year program, are more robust than typical approaches currently used to assess energy pipeline systems. The methodology deployed within a GIS environment provided rational means of distinguishing between seismically vulnerable sites, and facilitated the prioritization of remedial works. While ground improvement or pipeline retrofit measures were appropriate for upgrading most of the vulnerable sites, replacement of pipeline segments using horizontal directional drilling to avoid liquefiable zones were required for others.