New numerical simulations of blasts in concrete pipes with EUROPLEXUS

This report presents a series of numerical simulations, done by the EUROPLEXUS code [1], of experimental tests performed at the Norwegian University of Science and Technology (NTNU) about blast effects on tubular concrete (plain or reinforced) structures. These structures provide a simplified representation of a submerged floating tube bridge system built in concrete that has been proposed to provide an alternative to ferries to traverse fjords along the E39 coastal highway route along the west coast of Norway. The present study aims at assessing the capability of EPX of performing accurate simulations of a hypothetical (accidental or intentional) blast occurring in a tunnel, which can be used to assess the safety of the infrastructure. The present study follows that presented in references [6, 7] where a numerical model of the fluid sub-domain, including the detonation of the initially solid explosive charge, but using rigid (steel) pipes, had been calibrated and validated. In that work, some preliminary simulations of the concrete pipes had also been performed, but with less accurate results than in the rigid case. Recently, an improved set of experimental concrete material parameters has been calibrated and proposed by NTNU. Therefore, the present study aims at repeating the EPX simulations of concrete tests with the improved parameters, by also performing a parametric study on some particularly sensitive parameters of the DPDC material model of concrete in EPX, in an attempt to obtain a better agreement between the simulations and the experimental results and thus complete the validation of the computational model also for the case of plain or reinforced concrete structures. Keywords: Concrete pipe, explosion, blast, fluid-structure interaction.