Geotechnics of Pipeline System Response to Earthquakes

This paper addresses large-scale testing of pipeline response to earthquake-induced ground rupture and pipeline system performance after earthquakes. Described in detail are results of large-scale and select centrifuge tests on high density polyethylene (HDPE) and steel pipelines using the facilities of the George E. Brown, Jr. Network for Earthquake Engineering Simulation (NEES). Pipelines composed of HDPE are able to accommodate substantial amounts of abrupt ground displacement at strains and cross-sectional deformation well below those associated with pipe wall rupture and/or loss of serviceability. Measurements of lateral soil reaction with tactile force sensors compare favorably with independent load cell measurements, and demonstrate the effectiveness of tactile force sensor technology. Lateral forces generated by soil-pipeline interaction during ground rupture are similar for dry and partially saturated sand, and a log spiral model is described that predicts maximum horizontal forces on pipelines during ground rupture that agree very closely with large-scale test results. Pipeline system performance is evaluated through modeling the water supply system operated by the Los Angeles Department of Water and Power. The models are used to support decisions regarding the use of recently retired reservoirs on an emergency basis after a future earthquake. System models, calibrated by observed earthquake performance, provide the means for extending physical and numerical modeling results for components and individual pipelines to system behavior and the attendant planning and operational decisions to increase network reliability.