Uplift response of buried pipelines in saturated sand deposit under earthquake loading

Pipelines buried in saturated sand deposits, during earthquake loading could damage from resulting uplift due to excess pore water pressure generation. Several studies have been made to better understand the uplift mechanism and evaluate the effectiveness of mitigating techniques through experiment, but little numerical works have been done to assess the influence of soil properties and field conditions in pipeline floatation. Especially for previously buried pipelines, in order to set the priority for seismic retrofit, evaluating the risk of floatation in each region could be a concern. In this paper, effects of several parameters including dilatancy angle and density ratio of natural soil, diameter and burial depth of pipe, underground water table and thickness of the saturated soil layer on uplift of pipe have been investigated. Results show the prominent role of burial depth in pipe response and that there exits an optimum level for drop of water table to reduce floatation.

► We model the effect of several soil and pipe parameters on uplift response of buried pipelines in seismic regions.
► Increasing the density ratio of soil lessens the maximum uplift of pipe.
► There is a dilatancy angle at which the maximum uplift occurs in medium to dense sands.
► Larger diameter pipes undergo more uplift.
► There is an optimum level for falling of water table that the most influence on floatation reduction takes place.