An investigation into the upward and lateral soil-pipeline nteraction in sand using finite difference method

Permanent Ground Deformation (PGD), occurring as faulting, liquefaction-induced soil movements and landslides can significantly affect underground lifelines such as buried gas and water pipelines. This paper investigates the response of buried pipelines in sand to transverse PGD with particular attention to the peak forces exerted on the pipe. Available analytical solutions provide a wide range of predicted peak dimensionless forces, but there is limited information regarding the transition of the peak dimensionless force from shallow to deep embedment conditions. There are large uncertainties in the true values since the bounds established by the analytical solutions are large. In order to find the solution and to investigate its failure mechanism, the numerical modeling of soil-pipe interaction is performed for different conditions. The effects of burial depth ratio, pipe size and soil properties are addressed using finite differences analyses. A constitutive model for the continuous strain-hardening/softening and volumetric dilatancy of sand is proposed. The results showed that the transverse soil restraint decreases for larger diameter pipes in the horizontal direction, and there is no effect in the vertical direction. The transverse soil restraint increases with increasing burial depth ratio but it becomes constant at deeper soil profiles