Abstract: To study the law of shock wave propagation caused by blasting in long and large crosssection tunnels, the Baoding No. 2 tunnel on the PanzhihuaDali expressway is taken as an example to analyze the detonation products and shock waves in LSDYNA using 3D numerical simulation model. The overpressure criterion is introduced in this study. The research results show the following. (1) The maximum propagation distance of detonation products of 16 kg TNT explosive in the tunnel is 20 m. (2) The shock wave propagates to the surroundings in the form of "spherical symmetry" before it touches the tunnel wall, and finally propagates forward in the form of "twodimensional plane wave" after multiple reflections from the tunnel wall. (3) Affected by multiple reflections on the inner wall of the tunnel, the propagation law of the shock wave in the axial and radial overpressure time history curves is basically the same, accompanied by multiple wave peaks, showing obvious sawtooth attenuation. (4) When the shock wave propagates in the radial direction of the crosssection, the maximum overpressure suddenly increases at 3/4 radius from the tunnel axis, and the maximum overpressure at the tunnel wall is 1.3 times the maximum overpressure at the axis.

Key words: highway tunnel, blasting, shockwave, propagation law, numerical calculation