Wave-Induced Liquefaction and Floatation of a Pipeline in a Drum Centrifuge

Abstract

This paper discusses the floatation of a buried pipe in association with wave-induced liquefaction of sand beds. Centrifuge wave tests in a drum channel were performed with viscous scaling introduced such that the time-scaling laws for fluid wave propagation and consolidation of the soil were matched. The characteristics of liquefaction under irregular waves as well as regular waves were investigated. Under severe wave conditions, the loose sand beds underwent liquefaction, and the liquefied zone propagated downward in the course of wave loading. It was found that the floatation of the buried pipe was a consequence of progressive liquefaction. With the occurrence of liquefaction at a shallow soil depth, the buried pipe started moving upward and the motion of the pipe increased markedly in association with the downward progress of liquefaction during wave loading. Finally, the pipe reached the soil surface. The effects of a gravel layer replacement over a sand bed on wave-induced liquefaction and pipe floatation were also examined. A gravel cover over the sand bed with a range of 120°above the pipe prevented significant vibratory motion of the liquefied soil and floatation of the pipe.

Wave-induced residual response and liquefaction of a nonhomogeneous layered seabed

“…The predicted results of the models developed by and were comprehensively validated by the relevant centrifuge wave tests (Sassa and Sekiguchi, 1999). Using the same facilities as Sassa and Sekiguchi (1999), the marine structures of pipelines (Miyamoto et al, 2020) or pile foundations (Miyamoto et al, 2021) were further considered in their recent investigations. Because of the significantly increasing stress levels of soil, experimental observations in a centrifuge flume can be theoretically treated as an individual prototype in a real marine environment.…”