Two major earthquakes, in 1971 and in 1994, struck the same area of Los Angeles on Balboa Boulevard. The 6.6-magnitude San Fernando quake of 1971 did not result in any documented pipeline failures. However, the 6.7-level Northridge quake in 1994 caused significant damage, rupturing a natural gas transmission pipeline, a natural gas distribution pipeline, and two water trunk lines. The escaping natural gas caught fire and destroyed five homes. Why were there such different outcomes under similar circumstances? In a new study “Pipeline Response to Seismic Displacement at Balboa Boulevard during the 1994 Northridge Earthquake” the authors evaluated the seismic performance of buried pipelines at Balboa Boulevard.
Researchers Christopher A. Bain, Thomas D. O’Rourke, and Jonathan D. Bray used several different procedures to measure seismic ground displacement. The authors estimated the pipe strain with an analytical model and a single set of parameters. The analytical results of this study were in good agreement with the observed pipeline performance. The results of this study in the Journal of Geotechnical and Geoenvironmental Engineering apply to eight different pipelines in both tensile and compressive ground deformation zones. Learn more about this research at https://doi.org/10.1061/JGGEFK.GTENG-11886. The abstract is below.
Abstract
Seismic displacement at Balboa Boulevard during the 1994 MW 6.7 Northridge earthquake ruptured a high-pressure natural gas transmission pipeline, a natural gas distribution line, and two pressurized water trunk lines. Three other natural gas transmission pipelines and an oil transmission pipeline were not damaged. This paper presents the available geologic, geotechnical, and groundwater data at the site and summarizes past research efforts studying the seismic displacement during the Northridge earthquake. Characteristics and engineering properties of the pipelines and the soil–pipeline interface, including data not previously published in the public domain, are investigated and summarized. The pipe strains are estimated using an analytical model that accounts for the soil displacement pattern, nonlinear stress–strain characteristics of the pipe steel, and effects of bends and elbows. The expected pipeline performance compares well with the observed performance.
Learn more about what the pipeline performance findings can teach us today at the ASCE Library: https://doi.org/10.1061/JGGEFK.GTENG-11886.
