Liquefaction around pipelines under waves

This paper presents the results of an experimental study on liquefaction around a pipeline buried in a soil exposed to a progressive wave. The soil used in the experiments was silt with d(50)=0.045 turn. The pore-water pressure was measured in the far field and on the pipe simultaneously The tests indicate that the buildup of pore pressure and the resulting liquefaction in the soil are influenced by the presence of the pipe. The pore pressure builds up much more rapidly at the bottom of the pipe than in the far field (at the same level as the pipe bottom). By contrast, the buildup of pore pressure at the top of the pipe is not influenced radically by the presence of the pipe. The tests further indicate that as the liquefaction initially occurs in the very top layer and develops downwards, this picture changes in the vicinity of the pipe; in the latter case, the liquefaction initially occurs at the bottom of the pipe, and develops along the perimeter of the pipe upwards. The influence of the no-slip condition at the pipe surface on the end results has been investigated and found very significant. The influence of the wave height, the influence of the pipe diameter, the influence of the no-liquefaction-regime conditions, and the influence of a sinking pipe have also been investigated.