PIPELINE UPHEAVAL BUCKLING IN CLAYEY BACKFILL USING NUMERICAL ANALYSIS

Offshore pipelines used for oil and gas transportation are often buried to avoid damage from fishing activities and to provide thermal insulation. Thermal expansion and contraction of thepipeline during operation can lead to lateral or upheaval buckling. A safe buried pipeline design must take into account a reliable evaluation of soil uplift resistance and pipe embedment depth. While the cost of burying a pipeline for tens or hundreds of kilometer is significant, it isimportant to optimize the required soil cover depth. In this paper a parametric study of pipeline upheaval buckling in clayey backfill has been conducted using finite element analysis. Threedifferent embedment depths are considered. Uplift resistance is calculated and failure mechanismis obtained. The results reveal that as embedment depth increases, uplift resistance increases and also uplift mechanism changes. However, uplift resistance differ less than 5% for deep embedment case. In addition, the amount of pore pressure is investigated beneath the pipe for deep embedment cases and it reveals that negative excess pore pressure occurs under the pipeline.

کلیدواژه ها:

Subsea Pipeline ، Upheaval buckling ، Uplift Resistance ، Embedment depth ، ALE ، Uplift mechanism