Centrifuge modelling of active pipeline-soil loading under different impact angle in soft clay

This paper presents the results of physical modelling tests carried out in a geotechnical drum centrifuge to investigate the impact forces of submarine slide at debris flow stage acting on pipelines with various incident angles. The UK kaolin clay was used and normally consolidated clay samples were prepared at 40 g level. For each incident angle condition, the impact velocity was changed from 0.23 to 94.2 mm/s, and the influence of impact velocity and impact angle at low Re value are discussed. The present tests data were analyzed by geotechnical approach proposed by Randolph and White (2012). Then, a failure envelope was fitted to describe the impact force on pipeline caused by oblique debris flow. It was found that the normal bearing factor calculated by the present envelope was much lower than the result calculated by existing CFD envelope. While the frictional factor calculated by the present envelope was slightly higher than that of existing CFD envelope. By comparing the slide conditions of CFD calculations and present centrifuge tests, it should be noted that the present envelope was more appropriate to evaluate the impact force on pipeline due to slide with low impact velocity. When the Reynolds number was higher than 3, the existing CFD envelope was maybe more appropriate to evaluate the impact force on pipeline.