Abstract
The Norwegian Public Roads Administration has initiated a large research project on a potential ferry-free coastal highway route E39 from Trondheim to Kristiansand. Parts of this route involve crossing somewide and deep fjords, where one of the suggested crossing alternatives is a Submerged Floating Tunnel (SFT)built in concrete. A major concern regarding an SFT is internal blast loading from accidents involving gas orfuel tankers, or from terrorist attacks. To assess the performance of tubular concrete structures exposed to blastloading, 1760 mm long plain concrete pipes with an internal diameter of 200 mm and pipe wall thickness of41 mm were loaded by spherical C-4 charges of various sizes up to 25 g. Pressure sensors in different directionsequidistant from the charge location recorded the blast pressure, while two high-speed cameras captured theevents. Using mass produced commercial off-the-shelf pipes ensures consistent geometry and material proper-ties. A wooden pallet was used as support for the pipes, and an electrically initiated blasting cap was used todetonate the C-4. A charge size of at least 13 g C-4 was needed to breach the pipe wall. Larger charge sizescaused longitudinal cracks and broke the pipe into oblong pieces. The test results were used for comparisonwith simulations using the explicit finite element solver EUROPLEXUS, intended for fast transient dynam-ics involving fluid-structure interaction. Both purely Lagrangian simulations and fully coupled fluid-structureinteraction simulations were carried out. While the former method is more efficient computationally, the lat-ter approach accounts for reflections and the confinement of the pipe. It can be difficult to predict the exactcharge size where through-thickness cracking occurs, but the qualitative results were encouraging for furtherwork. When accurate simulations of the experiments are obtained, the simulations will be extended to a fullcross-section of a submerged floating tunnel.
Highlights
The Norwegian Public Roads Administration (NPRA) conducts a large research project aimed at making the coastal highway route E39 from Trondheim to Kristiansand ferry free [1]
To assess the performance of tubular concrete structures exposed to blast loading, plain concrete pipes were
The first, based on experimental data obtained by Kingery and Bulmash [8], consists of applying a pressure-time history to the inner surface of the concrete pipe based on the charge size, the distance to the charge, and the angle between each element’s surface normal and the direction towards the charge center
Summary
The Norwegian Public Roads Administration (NPRA) conducts a large research project aimed at making the coastal highway route E39 from Trondheim to Kristiansand ferry free [1]. A feasibility study has concluded that this is a viable concept [2]. The concept involves various challenges; fluid-structure interaction (FSI) was studied by Remseth et al [3] for this type of structure, while impact from ships has been investigated as well [4]. Blast loading in an SFT is currently under investigation by means of concrete slabs [5], because a major concern regarding an SFT is internal blast loading. Such loading may originate from accidents involving tankers transporting dangerous cargo like liquid natural gas or gasoline, or from a terrorist attack. To assess the performance of tubular concrete structures exposed to blast loading, plain concrete pipes were
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