Abstract: The influence of shaft height and cross-sectional area on smoke movement pattern in shaft is studied by carrying out similar experiments under the conditions of better opposite jet velocity and different fire power. The experimental results show that the increase of shaft height and cross-sectional area will promote the occurrence of plug-holing; The larger the cross-sectional area of the shaft, the smaller the corresponding critical shaft height; The critical value of Ri under experimental conditions is 0.56. When Ri value is less than 0.56, boundary layer separation mainly occurs in the shaft, and when Ri value is greater than 0.56, plug-holing occurs.

Key words: highway tunnel, shaft smoke exhaust, plug-holing, boundary layer separation, opposing jet