Impact Effect on the Behavior of Land and Underwater Pipes

Abstract

Pipelines are under the effects of destructive sudden loads including accidental drops, ship anchors, rock falls, trawlers fishing and military attacks in addition to environmental loads. In this study, finite elements method (FEM) supported numerical and semi-analytical analyses of the same pipe section have been carried out according to the sudden loads caused by falling objects both underwater and on land. Abaqus finite elements analysis software is used in the numeric analysis. While the pipe-falling object interaction is modelled in the analysis of the pipeline on land, the pipe-falling object-water interaction is modelled in the underwater pipeline. Bidirectional fluid-structure interaction (FSI) analysis is utilized in the water-pipe-falling object interaction modelling. A fully nonlinear free surface simulation is performed by Coupled Eulerian Lagrangian (CEL) technique in the FSI analysis. Impact parameters such as accelerations, displacements impact forces and energy absorption, are determined for both land and underwater pipe sections. Semi-analytical solutions of the pipe models have been generated by using the resulting impact forces. Thus, numerical analyses have been verified with the semi-analytical models. In addition, the effect of water on impact behaviour as well as the free surface movement of water during impact effect has also been determined.