Influence of length and angle of bifurcated tunnel on shock wave propagation

Abstract

In order to study the influence law of bifurcated tunnel on the overpressure propagation of gas explosion shock wave, the variation law of overpressure of shock wave in main tunnel under different lengths and included angles of bifurcated tunnel was studied by numerical simulation. The results showed that: 1) the length of bifurcation tunnel had different effects on shock wave propagation when the bifurcated tunnel was opened and closed. The length of the bifurcated tunnel had no effect on the shock overpressure in the main tunnel, when the bifurcated tunnel was opened. When the bifurcated tunnel was closed, the length of the bifurcated tunnel had a great influence on the shock wave overpressure in the main tunnel, showing a tendency of decreasing first and then tending to be stable. When the included angle of the bifurcation tunnel was 45°, the overpressure at the monitoring point decreased from 368.7 kPa to 291.5 kPa, with a decreasing rate of 28.6%, and then fluctuated slightly around 291.5 kPa 2) The bifurcation of bifurcated tunnel had a consistent effect on the peak overpressure of shock wave despite of the opening and closing of bifurcated tunnel. The shock wave overpressure in the main tunnel increased first and then decreased with the increase of the included angle of the bifurcated tunnel, and the peak overpressure was the highest when θ = 90°, with 333.1 kPa for open and 333.4 kPa for closed. When 45° < θ < 90°, the shock wave overpressure in main tunnel increased rapidly with the increase of angle, with an increase rate of 14.3%. When 90° < θ < 135°, shock wave overpressure slowly decreased with the increasing of angle, with a decreasing rate of 2.9%. 3) In numerical simulation of gas explosion, the geometric model of tunnel net can be reasonably simplified according to the influence law of the length of bifurcated tunnel on the shock wave of main tunnel. The end of emergency lane and other chamber should be arranged 50 m away from the crossing point.