In 1999, the working group ndegrees6 " Fire and Smoke Control " of the PIARC Ccontrol in road tunnels ". The recommendations on the ventilation control mention an evacuation phase followed by a fire-fighting phase. During the refurbishment of the Mont Blanc tunnel, these recommendations are at the base of the regulation rules used for controlling the ventilation system in the case of a fire. For the evacuation phase, the bidirectional character of the traffic imposes to control the conditions of development of the natural stratification of the hot smoke. This objective is achieved by associating the operation of jet fans with the activation of a capacity of extraction centred on the fire, as soon as the operator validates the location of fire. This system, entirely automatic, was tested during full-scale tests in January 2002. The results are exceptional since, during the most powerful fires (8 MW), the maximum extension of the smoke (perfectly stratified) was 300 m. These tests played an essential role in the decision of re-opening the tunnel. The publication summarily describes the Mont Blanc tunnel and its ventilation system. It presents the scientific bases of the development of the stratification. It gives finally a description of the full-scale tests and synthesises interpretations of the mechanisms that were observed on this occasion. For the covering abstract see ITRD E135448.
Abstract