Thermal protection and spalling

Thermal protection boards
Pre-qualification tests
Gas tempertures
Thermal protection and spalling
Heat release rate
Radiation levels near fire
Results and behaviour on the PROMATECT®-T lining

As shown in the figure below the tunnel was protected with PROMATECT®-T boards. This was done for safety reasons to avoid rocks falling from the tunnel structure.

thermal protection with fire resistant board system in tunnel

A distance of 75 m of the tunnel ceiling was protected, while 25 m of the walls (near the fire) was protected with these boards. Downstream of the board walls, the rock was protected using ceramic curtains mainly to minimise the flow of hot gases above the protecting ceiling. Such hot gases could otherwise affect both the rock ceiling and the steel structure on which the boards were hanging. Upstream of the board walls, a distance of 9 m was also protected with ceramic curtains, although not all the way down to the road. This was done to keep the back-layering gases below the protecting ceiling. It was obvious that this protection was needed during and after the first test, when large rocks fell down onto the road both upstream and downstream of the protection. Downstream of the protection, the tunnel ceiling was affected almost all the way to the western tunnel entrance.

The rocks falling down upstream of the protection was a result of the back-layering taking place in spite of the ventilation.

20 m upstream, in the area were the rock was not protected against the fire, at 80-100º C, spalling rock has been recorded, resulting in large blocks of rock falling down in the area where the fire brigade would be expected to attack the fire. This would endanger the fire fighters and hamper their ability to do their work.

test tunnel fire protection with promatect boards
pictures of rocks in tunnel after fire


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A report containing the set-up of the tests, the recordings of the data and the interpretation of the results was issued by Uptun, TNO and our company.

The report also contains a cd-rom with all the pictures and video’s of the set-up and the fire tests, as well as all the technical/scientifical papers.