Soil-Pipe Interaction Characterization for Seismically-Induced Longitudinal Permanent Ground Displacements

Buried water and wastewater pipeline infrastructure located in regions with increased seismic activity are vulnerable to damage from seismically induced geo-hazards. Two types of geohazards are possible: (1) wave propagation hazard; and (2) permanent ground deformation (PGD) hazard. While earthquake-induced transient wave propagation can lead to damage of some pipe systems, permanent ground deformations (PGD) such as those imposed by landslides, liquefaction-induced lateral spreads, and fault rupture have been shown to be particularly damaging to buried pipelines. While pipeline response is dependent on the soil-pipe interaction behavior, the pipeline response related to seismically induced longitudinal PGD is heavily influenced by the frictional resistance that develops from relative displacement between the soil and pipe at the soil-pipe interface. The frictional resistance along the pipeline is dependent on the pipe material, joint geometry, soil type, cover over the pipe, and pipe diameter among other things. The American Society of Civil Engineers (ASCE) is currently developing a manual of practice (MOP) for the Seismic Design of Water and Wastewater Pipelines under the Pipeline Division of the Utility Engineering and Surveying Institute (UESI) in collaboration with ASCE’s Infrastructure Resilience Division (IRD). To aid the MOP development, simple soil-pipe interaction analyses have been undertaken by the task committee to characterize the longitudinal frictional resistance force along continuous and segmented pipelines constructed of different pipe materials. This paper presents a description of the analyses completed, results obtained, and recommendations developed including proposed equations to characterize frictional behavior at the soil-pipe interface and suggested parameters suitable for different pipe materials, joint geometry, soil types, and installation conditions.