An Analysis of the Consequences from an Explosion in a Road Tunnel with Concrete Walls and Roof
Published: 14 April, 2010
There are plans to exploit the area above an urban motorway road tunnel in the northern part of Stockholm city for building workplaces and possibly also dwelling houses. Since the motorway is a primary transport route for dangerous goods a risk may arise from an accidental explosion inside the tunnel. As a support of the risk analysis process and to provide support for the design of reinforced concrete structures such as tunnel walls and roof, the consequences of explosions in the tunnel were
calculated
Charges with weights corresponding to 2000 kg or 4000 kg of TNT were considered at different locations inside the tunnel. The explosion pressure load in a specific location inside the tunnel becomes rather complicated due to reflections from the inner surfaces of the tunnel. To calculate the pressure at different points inside the tunnel the analysis tool AUTODYN was utilized.
In order to determine the response in terms of deformation and possible collapse of the reinforced concrete tunnel wall and roof slabs from the explosion pressure load, a single degree of freedom analysis was performed. Assumptions and results of the calculations in terms of pressure load, deflection of structures and length along the tunnel of wall or roof collapse will be presented, as well as suggested risk reducing measures.
The paper also contains examples on pressure loads on a facade of a building located above the tunnel roof slab if an explosion takes place immediately outside the opening of the tunnel. This is illustrated both with calculations and scale model tests.
