Estimation of pressure distribution for shock wave through the junction of branch gallery

Propagation of the air shock wave caused by explosion via the branch gallery, a popular phenomenon in a large number of practical accidents of underground mine explosions, quite different from its propagation in a straight gallery, has been studied in this work by means of the numerical simulation approach based on the commercial finite element software ANSYS/LS-DYNA, in order to meet the requirements of analyzing the accidents of explosions in underground mines and estimating the blast resistance of underground structures in those mines. Attenuation of the peak overpressure with distance does not obey exponent law for the air shock wave through a branch gallery, and the overpressures at some locations within the junction zone are higher than those nearby them. The front of the original plane wave bends in the branch of the gallery, and after passing through the junction, gradually returns its state of plane wave propagation. There is a span dependent on the cross section dimension of the laneway and increasing with its branch angle, in which the peak overpressure of shock wave does not uniformly attenuate with distance. The pressure distribution at each section either in the main gallery or the branch via a junction depends on the branch angle, decreasing in the branch gallery after the junction with it, while increasing in the main gallery. The pressures in the branch gallery after the junctions with 45°, 90° and 135° are 1/3.08, 1/4.05 and 1/4.57 times, respectively, as large as the values before the bifurcation, and those in the main gallery after the junctions with 45°, 90° and 135° are 1/2.04, 1/1.88 and 1/1.85 times as large as the pressures before the junctions, respectively.

► Pressure in branch after junction with 45° is 1/3.08 times as large as values before junction.
► Pressure in branch after junction with 90° is 1/4.05 times as large as values before junction.
► Pressure in branch after junction with 135° is 1/4.57 times as large as values before junction.
► Pressure in main gallery after junction with 45° is 1/2.04 times as large as values before junction.
► Pressure in main gallery after junction with 90° is 1/1.88 times as large as values before junction.