Propagation Law Of Blast Shock Wave In Tunnel And Tunnel Dynamic Response Research

With the rapid development of precision-guided weapons and new ground-drilling weapons,the tunnels in underground,semi-underground,or mountain structures are more likely to be hit by missiles and explode inside.Explosive explosion is a rapid chemical dynamic reaction process,which is accompanied by high-pressure gas expansion and shock wave propagation,which has a strong destructive effect.Due to the different direction,structure and environment of the tunnel,when explosives explode in the tunnel,the shock wave will produce complex reflection,superposition,and diffusion phenomena in the tunnel.The tunnel structure and facilities are easily damaged under the action of the explosion shock wave,and the people inside are easily injured or killed under the action of overpressure.Therefore,in the tunnel structure design,it is necessary to consider the damage caused by the explosion,and the study of the propagation law of the explosion shock wave and the destruction effect in the tunnel is particularly important.In this paper,using numerical simulation and experimental verification methods,the formation and propagation of explosion shock waves in tunnels and the dynamic response of tunnel structures under explosive loads are systematically studied.The details are as follows:First of all,according to the relevant theories of the explosion shock wave,various phenomena in the shock wave propagation,such as Mach reflection,circumfluence phenomenon,etc.are studied;relying on the AUTODYN software,the mapping calculation method is established,and the physical model is established and the constitutive model and parameters are established.Reasonable selection.By comparing the experiment of Professor Ren Xinjian,the error between the numerical simulation and the experiment was less than 6%,which verified the correctness of the numerical simulation and laid the foundation for subsequent research work.Then,the law of formation and propagation of explosion shock wave in the tunnel was studied.The similarity law of explosion in long straight tunnels is studied,and the conditions that the similarity law needs to meet are obtained.The influence of the position of the explosion point in the long straight tunnel on the formation and propagation of shock waves was studied.The farther the explosion point is from the axis position,the longer the reflection and oscillation of the shock wave in the tunnel lasts,and the longer the time and distance required to form a plane wave.The reflection,superposition and attenuation of shock waves in the Lshaped tunnel are studied.When shock waves propagate to the corner,reflection and superposition will occur.Part of the reflected waves return to the original tunnel,and part of the reflected waves pass to the next tunnel.The peak value of the shock wave decreases after the corner;The reflection and circumfluence of the explosion shock wave in the T-shaped tunnel,the lower tunnel,the left tunnel and the intersection are analyzed,and the propagation and attenuation laws are summarized.Finally,the dynamic response of the tunnel under explosive load is studied.The dynamic response laws of different tunnel structures under different explosion points are analyzed.The destruction of tunnels is mainly concentrated in a very short time after the explosion,with fast response（0.003ms～0.05 ms,reaching the microsecond level）and large load（from several Ten to several hundred megapascals）and short duration（0.3ms～3ms）.In the tunnel,its maximum stress,strain,displacement and velocity all decrease with the increase of the burst center distance.In the L-shaped tunnel,stress concentration will occur at the outer corner of the tunnel wall,which is the most vulnerable position in the structure.In the T-shaped tunnel,the center of the upper wall and the left and right corners are the most concentrated parts of the explosion load,and the center of the upper wall is the most vulnerable part.