Influence of ground motion characteristics on liquefaction-induced pipe uplift

Abstract

Soil liquefaction occurring due to earthquakes poses severe risk to both above-ground structures as well as buried structures such as pipes, manholes etc. During liquefaction, the shear strength of the soil above and around the pipeline could decrease due to build-up of excess pore pressures and, subsequently, resulting in buoyancy forces that could cause the pipelines to displace and potentially “float up” towards the ground surface. Limit-equilibrium based procedures allow for prediction of uplift occurrence, but predicting the magnitude of uplift is a complex task with a number of components such as soil type, pipe diameter (D) and burial depth (H), pipe boundary constraints, and earthquake motion contributing to this mechanism. This study utilizes a well-calibrated and validated 2D numerical model to investigate the effects of input motion characteristics on pipe uplift for a steel pipe buried in a saturated, loose, and homogeneous deposit of Fraser River sand. The commercially available finite difference FLAC software and soil constitutive model PM4Sand were utilized. The influence of input motion amplitude and duration on uplift behavior of pipe was examined and discussed.