Longitudinal Permanent Ground Deformation Effects on Buried Continuous Pipelines

Abstract

The response of buried steel pipelines to permanent ground displacement is investigated. Specifically, pipeline response to four different idealized patterns of longitudinal permanent ground deformation, wherein the non-recoverable soil movement is parallel to the pipeline axis, is considered. The pipe material is assumed to be linear elastic while the force-deformation relationship of the soil-pipeline interface is taken to be elasto-plastic (elastic spring-slider) or rigid-plastic (rigid spring-slider). The four patterns of longitudinal permanent ground deformation investigated are idealizations of patterns observed in past earthquakes. They are: a) uniform ground strain (Ramp), and b) symmetric uniform ground strain (Ridge). For the first two patterns, the exact response is determined and compared with a simplified model which neglects the elastic portion of the force-deformation relationship at soil-pipeline interaction. It is found that the simplified models predict maximum pipeline strains within 5 percent of the exact values. For the third and fourth patterns of longitudinal permanent ground deformation, results are presented for the simplified interface model (rigid spring-slider) only.