Wave force reduction due to burial of submarine pipeline: A probability based analysis and comparison with DNVGL-RP-F109

Horizontal and vertical wave forces were assessed on submarine pipeline for different burial depths in soils of four different hydraulic conductivity in random waves of wide range of wave height and periods. Probability analysis is carried out for 99.99% and 98% probability of non-exceedance of vertical and horizontal wave forces on the pipeline. The force reduction due to burial of the pipelines are compared with the recommendations by DNVGL-RP-F109. The effect of changing the wave height, wave period and hydraulic conductivity on the wave forces and its change due to different burial depths are revealed. The wave force values and the quantitative differences due to 99.99% and 98% probability of non-exceedance can be used for risk-based design of buried pipelines. The recommended value of wave force reduction factor for different relative burial depth of the pipeline by DNVGL-RP-F109 is much smaller than the value of wave force reduction factor from the present study. Strong scope exists to revise this code for the betterment of submarine pipeline design engineers. The knowhow revealed in this study will be useful for optimal design of buried submarine pipelines.