Numerical study for wave-induced pore pressure accumulations around buried pipeline: Effects of back-fill trench layer

Abstract

In general, a cover layer with applicable backfill materials can reduce the potential of the waveinduced liquefaction around offshore pipelines. The evaluation of wave-induced pore pressure around a trenched pipeline in the marine sediments have been extensively investigated in the past few decades. Most previous studies regarding the effects of a cover layer considered full backfilled conditions, although general engineering practises normally used partially backfill, rather than fully backfill. In this study, an integrated numerical model is proposed to perform a simple scaling analysis to clarify the applicable ranges of the thickness (Hb) of backfill material related to different wave conditions, in which the bottom of the buried pipeline are fully prevented from being liquefied. Based on the numerical results, it is found that the thickness of backfill material significantly affect the wave-induced accumulated pore pressure around the trenched pipeline, and the seabed at the bottom of the pipeline are easier to be liquefied with shallow backfill depth under high wave loading.