Physical and Numerical Modelling of Pipe Penetration at Transition Depths

Description

The mechanism of pipe penetration into the seabed has important implications in a wide range of applications, for example in predicting initial pipe embedment for on-bottom pipelines and in offshore site investigation using a T-bar penetrometer. Extensive research has been conducted to identify the relationship between the applied vertical load and the resulting penetration for either very shallow or very deep embedments. The transition between these two extremes has however not received enough attention.This research examines the limiting load of a pipe penetrated to different depths. Numerical slip-line mechanism solutions will be developed, taking into account the change in soil geometry as the pipe penetrates. The results will be verified by a series of model tests in which pipes of different sizes will be pushed into soft clay, with the applied load and vertical displacement measured. A pipe penetration factor will be proposed as a function of pipe embedment to link the undrained soil strength, the vertical load, and the pipe embedment.