Propagation Characteristics of Blasting Shock Wave in Variable Cross Section of Tunnel
In order to study the propagation law of blasting shock wave in the complex environment of tunnel,based on Laoyingpan tunnel,the propagation law of shock wave under different coefficients of tunnel section change was analyzed in LS-DYNA software by establishing a three-dimensional numerical model.The results show that after the shock wave passes through the variable cross section,it generally propagates in the form of plane wave.When the shock wave propagates to the enlarged interface of the tunnel section,the attenuation speed of the shock wave overpressure is accelerated and the overpressure peak is reduced.When the section is enlarged by 1.5 times,the attenuation coefficient of shock wave impulse is 1.158,and the residual ratio of shock wave energy is 74.5％.The larger the expansion ratio of the cross section,the greater the attenuation speed of the shock wave overpressure and the greater the energy attenuation amplitude.When the shock wave propagates to the reduced interface of the tunnel section,the overpressure of the shock wave increases,and its attenuation rate slows down,resulting in an increase in the degree of damage caused by the shock wave.When the section reduction coefficient is 0.5,the shock wave impulse enhancement coefficient is 0.687,and the shock wave energy amplification coefficient is 2.122.The smaller the reduction coefficient of the section,the greater the damage caused by the shock wave.
highway tunnelsshock wavevariable cross-sectionlaws of transmission
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