Study on smoke control efficiency in ultra-long railway tunnel under fire condition

Proper smoke control design is an important aspect in the operating security of ultra-long railway tunnels. Taihang Mountain Tunnel on Shijiazhuang-Taiyuan Passenger Specified Railway is investigated as a typical case. The numerical model representing the smoke control design and fire scenarios is set up, based on which the smoke motion and the efficiency of different smoke control plans under several fire conditions are simulated. By comparing the results, it could be drawn that the huge sectional area of the tunnel is capable of cumulating a great quantity of smoke, and effect of axial flow fan is relatively minor, while the longitudinal air flow driven by jet fan could efficiently damp the spread of smoke. Some specific phenomenons that deserve attention in the design and operation of such tunnels are also raised in this paper.