Numerical Simulation of a Subsea Pipeline Subjected to Underwater Explosion Loads With the Coupled Eulerian-Lagrangian (CEL) Method Zhenhui Liu ∗ Department of Mechanical and Marine Engineering Faculty of Engineering and Science Western Norway University of Applied Science Haugesund, 5528 Norway Email: Zhenhui.Liu@hvl.no Ove Tobias Gudmestad Department of Maritime Studies Faculty of Business Administration and Social Sciences Western Norway University of Applied Science Haugesund, 5528 Norway Email: Ove.Tobias.Gudmestad@hvl.no Ragnar Igland Department of Front End Engineering Aker Solutions AS Trondheim, 7044 Norway Email: Ragnar.Igland@akersolutions.com The relevance of the paper is the need for removal of a 1 large number of UXO (unexploded ordnance) on the Nor- 2 wegian continental shelf during the installation of sub- 3 sea pipelines. This paper tries to include the seabed in 4 the simulation by using the Coupled Eulerian-Lagrangian 5 (CEL) method. The effects of water, soil and the TNT 6 are approached by using the Eulerian formulation with 7 specified Equation of status (EOS). The Us-Up’s form of 8 Mie-Gruneisen equation is used for the water and soil. 9 The soil’s strength is described by linear Drucker-Prager 10 yielding function. The Jones-Wilkins-Lee (JWL) equation 11 of state is used for TNT. The steel pipe is approached by 12 shell elements in a Lagrangian scheme. The strain rate 13 effects on steel strength and failure strain have been con- 14 sidered through the Cowper and Symonds equation. The 15 coupling between Eulerian and Lagrangian formulation 16 is done by the general contact features provided by the 17 Abaqus Explicit solver. Three offset distances (2.5 m, 5 18 m and 15 m) have been simulated. The simulation re- 19 sults are discussed in details with respect to the water, 20 soil, TNT and pipeline deformations respectively. Addi- 21 * Address all correspondence to this author. tionally, the axial force is also discussed. It is shown that 22 the present numerical model is able to capture the main 23 characteristics of such a complicated physical process. 24 The influence of the seabed has been shown explicitly in 25 all the offset distances analyzed. The empirical factor 26 method may give over-conservative results. 27 NOMENCLATURE OD Outer diameter pipeline, [m] and [inch] 28 WT Wall thickness pipeline, [m] 29 d penetration distance, [m] 30 ρ TNT Density of TNT, [kg/m 3 ] 31 A, B constant ftting parameters in JWL EOS, [Pa] 32 R 1 ,R 2 constant ftting parameters in JWL EOS, [-] 33 ω the fractional part of the energy contributing for the 34 pressure, [-] 35 E internal energy per unit mass, [J/kg] 36 P shock wave pressure from JWL EOS, [Pa] 37 V Specifc volume of detonation products over the spe- 38 cifc volume of un-detonated explosions,[-] 39 ρ water Density of water, [kg/m 3 ] 40