Assessment of the Below-Ground Trans-Alaska Pipeline Following the Magnitude 7.9 Denali Fault Earthquake

Nearly half of the 800-mile (1,287-km) Trans-Alaska Pipeline System (TAPS) is buried in a standard pipeline trench with a minimum depth of cover of 0.9 m (3 feet). The magnitude 7.9 Denali Fault earthquake produced peak ground motions of 0.34 g at a location 5 km from the fault. The duration of shaking was approximately 90 seconds, contributing to liquefaction of subsurface deposits along the pipeline as evident from numerous sand boils. In some areas in proximity to the Denali Fault crossing, moderate lateral spread movements occurred. Landsliding did not occur along or across the pipeline right-of-way itself, although there were a number of landslides and rock falls that occurred proximate to the Denali Fault zone several tens of kilometers west of the pipeline. The near-source violent motions coupled with soil liquefaction provided the opportunity for developing significant bending and axial strain in the buried pipeline. The pipeline was excavated at a location where evidence suggested lateral spreading or subsidence due to liquefaction, but no damage to the pipe was observed. Approximately one month after the earthquake, the pipeline was inspected using an instrumented in-line monitoring device ("smart pig") capable of detecting pipeline curvature and deformation. No evidence of pipe deformation, strain increases, or curvature changes in excess of acceptable limits were observed. This paper provides an overview of the field reconnaissance of the below-ground pipeline segments in proximity to the Denali Fault, observations of liquefaction and ground failure, and a discussion of the use of an instrumented pig to validate pipeline structural integrity.


  • English

Media Info

  • Media Type: Web
  • Features: References;
  • Pagination: pp 566-575
  • Monograph Title: Advancing Mitigation Technologies and Disaster Response for Lifeline Systems

Subject/Index Terms

Filing Info

  • Accession Number: 01893571
  • Record Type: Publication
  • ISBN: 9780784406878
  • Files: TRIS, ASCE
  • Created Date: Sep 19 2023 9:27AM