Dynamic Response of Pressurized Submarine Pipelines Subjected To Transverse Impact Loads

Accidental impacts are a common source of damage in submarine pipelines. In this article, response of internally pressurized steel pipelines subjected to lateral dynamic impact loads has been studied using a three dimensional finite element simulation. The numerical model has first been validated against experimental data from other researchers. Moderately thick wall steel tubes that may show noticeable inelastic deformations during lateral impacts have been considered in the study. Geometrical and material nonlinearities in the tube body and in the sub-soil medium have been taken into consideration. Effects from internal fluid pressure, dynamic wave propagation in the internal fluid, velocity of the dropped object, embedment depth of the pipe and soil bed properties have been investigated. It was found that the sea bed properties may have important effects on the extent of denting, especially at relatively low internal pressures. It has also been shown that with increase in the embedment depth of the pipe into the bed, the maximum impact load and maximum dent depth were increasing but the permanent dent did not completely follow suite.