Uplift Resistance of Pipelines Buried in Compacted and Uncompacted Sands Using Field Tests

Upheaval buckling (UHB) is a common design issue for buried pipelines when the out-of-straightness of the pipeline combined with the high axial compressive forces induced by the extreme operating conditions causes the pipeline to buckle upwards. It is common to mitigate UHB for onshore pipelines by having deeper burial depths. However, a more practical and cost-effective solution would be to use compacted backfill, which would provide higher uplift resistance and smaller mobilization for buried onshore pipelines. Knowledge of uplift resistance in compacted soil is limited in the literature. This paper presents results from full-scale experiments in which uplift resistance of compacted and uncompacted soil was measured for cover depths ranging from 1.2 to 2.4 m. The effect of the degree of compaction, cover height, and backfill unit weights on uplift resistance and mobilization is presented. A new analytical relationship between the uplift resistance and displacement is proposed for pipelines buried in sand backfills in compacted and uncompacted states.