Experiment on Performance of Buried Pipelines Across San Andreas Fault

Keywords: Lifelines, Buried Pipelines, San Andreas Fault, Parkfield, California, Parkfield-Cholame Earthquake, 1966, Seismic Response, Tensile Stress, Ground Motion, Seismometry, and Wave Propagation.

Abstract: A field experiment designed to investigate the performance of buried pipelines at a fault crossing has been constructed near Parkfield, CA. The site was chosen to capitalize on the predicted recurrence of the 1966 Parkfield-Cholame earthquake sequence. Monuments for measuring lateral offset and strong motion seismomenters have been placed at the site and are being monitored. Thirty-six strain gauges have been attached to two segments of welded steel pipe to measure length changes and flexure. Twelve displacement transducers have been installed in jointed ductile iron pipe to measure rotation and extension at the joints. Data are recorded when preassigned thresholds levels of strain in selected trigger channels are exceeded. Since seismic activity has been low, no records of pipeline response have been obtained yet. The accomplishments of 1988 include measuring the stress-strain properties of the pipeline steel and shear strength of the interface between sand and steel. Three strong motion seismometers, obtained through a cooperative agreement with the Urban Hazards Research Institute of the University of Kyoto, Japan, were put in place. Survey monuments were also emplaced and are monitored regularly by the US Geological Survey. The concrete anchors which are intended to prevent relative displacement between the pipe and the adjacent soil at the ends of the welded steel pipes were enlarged. Future work includes upgrading the data acquisition rate such that the strain measurements and ground strains derived from the seismometers are both resolved up to 8-10 Hz and further reducing noise in a few strain gauge channels.