Numerical Simulation of a Subsea Pipeline Subjected to Underwater Explosion Loads With the Coupled Eulerian–Lagrangian Method

Abstract

The relevance of the paper is the need for the removal of a large number of unexploded ordnance (UXO) on the Norwegian continental shelf during the installation of subsea pipelines. This paper tries to include the seabed in the simulation by using the coupled Eulerian–Lagrangian (CEL) method. The effects of water, soil, and trinitrotoluene (TNT) are approached by using the Eulerian formulation with a specified equation of status (EOS). The Us − Up’s form of Mie–Gruneisen equation is used for the water and soil. The soil’s strength is described by the linear Drucker–Prager yielding function. The Jones–Wilkins–Lee (JWL) equation of state is used for TNT. The steel pipe is approached by shell elements in a Lagrangian scheme. The strain rate effects on steel strength and failure strain have been considered through the Cowper and Symonds equation. The coupling between Eulerian and Lagrangian formulation is done by the general contact features provided by the Abaqus explicit solver. Three offset distances (2.5 m, 5 m, and 15 m) have been simulated. The simulation results are discussed in detail with respect to the water, soil, TNT, and pipeline deformations, respectively. Additionally, the axial force is also discussed. It is shown that the present numerical model is able to capture the main characteristics of such a complicated physical process. The influence of the seabed has been shown explicitly in all the offset distances analyzed. The empirical factor method may give over-conservative results.