Experimental studies on the smoke extraction and smoke control performance by the ventilation shaft in extra-long road tunnels

Abstract

Ventilation shaft is widely employed in the extra-long road tunnels in China. For deeper understandings of the smoke extraction and smoke control characteristics of the ventilation shaft, a total of 98 experiments were conducted in a 1/20 model scale tunnel. The effects of heat release rate, board location, and operation frequency were investigated. The results indicate that the mechanical board-coupled shaft (MBCS) can achieve better smoke extraction and smoke control performances than the traditional mechanical ventilation shaft (MTS). Though further research on the MBCS, it can be found that smoke extraction and smoke control performance of the MBCS are highly affected by the board location and operation frequency. Besides, as the power of the fire source increases, the smoke extraction performance of the MBCS increases, but the corresponding smoke control will be more difficult. Moreover, it was found that the optimal operation conditions for the MBCS to achieve the best smoke extraction performance and smoke control performance are different. Therefore, the uniform parameter for characterizing both the smoke extraction performance and the smoke control performance was established. And based on this parameter, the overall performance of the MBCS under different operation conditions can be compared, which may contribute positive significance in the smoke control and extraction design with extra-long road tunnels.