Task Description – The most serious damage to underground pipelines during an earthquake is caused by permanent ground deformation resulting from liquefaction, fault rupture, and landslides. The scope of this research program includes summarizing the procedures and data available in California for assessing liquefaction triggering, liquefaction-induced lateral spreading and vertical settlement, and seismic slope instability and displacement at a statewide, regional, and site-speciﬁc scale. Through this, a new procedure for probabilistically assessing liquefaction triggering and lateral spread displacement at regional scales is introduced and implemented into OpenSRA.
Additionally, this program summarizes the results of existing pipeline test data and the ﬁndings from physical testing studies of buried pipelines that explore soil-structure interaction effects. The ﬁnite element computer program Abaqus was used to assess generic cases of underground pipeline response to four modes of permanent ground deformation: 1) strike-slip tension, 2) strike-slip compression, 3) normal-slip, and 4) reverse-slip. The Abaqus results are the basis for deriving fragility functions (refer to Fragility Development scope) to estimate tensile and compressive pipe strain to buried pipelines subjected to permanent ground deformations from fault rupture, landslide displacement, or liquefaction-induced lateral spreading or vertical settlement. A ﬁfth mode of ground deformation, where the ground deforms in a direction parallel to the longitudinal pipeline axis resulting in tension at the scarp and compression at the toe, was also evaluated using an analytical model.
Overall this team has:
- Summarized procedures for assessing
· Liquefaction triggering
· Liquefaction induced lateral spreading and vertical settlement
· Seismic slope instability and displacement
Presented a new procedure for assessing liquefaction triggering and lateral spread displacement at a regional scale
Summarized existing pipeline test data and findings from testing
Developed a finite element model to assess permanent ground deformation due to fault shear through a pipeline
· Strike-slip tension
· Strike-slip compression
· Parallel to longitudinal pipeline axis
Lead Investigator: Jonathan Bray (University of California, Berkeley)
Team Members: Tom O’Rourke, Scott Lindvall (Lettis Consultants International, LCI), Kenichi Soga (University of California, Berkeley), Chris Bain (University of California, Berkeley), Daniel Hutabarat (University of California, Berkeley)