Study On Propagation Characteristics Of Blast Wave In Road Tunnel

In the process of tunnel construction,the air shock wave produced by excavation blasting will affect the tunnel construction environment and surrounding residents.The blasting shock wave is reflected and superimposed by the constraint of the tunnel wall,which attenuates more slowly,and the damage effect is often more serious,posing a great threat to the safety of personnel and equipment in the tunnel.Therefore,it is necessary to analyze the propagation characteristics of blasting shock wave in highway tunnel,so as to provide reference for the safety protection of blasting shock wave and have certain guiding significance for engineering practice.Based on the Shengli tunnel project of Ningnan Panzhihua expressway of g4216 line,combined with the methods of data investigation,theoretical analysis,numerical simulation and field test,this paper analyzes the propagation law and characteristics of blasting shock wave in Shengli tunnel constructed by bench method,and discusses the influence of section changes and obstacles on the propagation of blasting shock wave.The main research contents and results are as follows:(1)Using the display dynamic analysis finite element software ANSYS/LS-DYNA,combined with the blasting scheme at the construction site of Shengli tunnel of Nanjing Panzhihua expressway,the propagation process of blasting shock wave on the upper bench of Shengli tunnel is numerically simulated.The basic characteristics of blasting shock wave propagation in highway tunnel are studied by analyzing the change of shock wave flow field,cross-sectional overpressure distribution and longitudinal overpressure attenuation.(2)Similarly,based on the structure of Shengli tunnel,the propagation characteristics of blasting shock wave in different complex environments are studied.By establishing a threedimensional numerical model,the propagation process of blasting shock wave in cross-section changes and obstacles is simulated successively.Then,on this basis,the effects of different times of section expansion,different coefficients of reduction and the size of obstacles on shock wave propagation are studied,and the changes of shock wave overpressure or energy in different tunnel models are determined.(3)The blasting shock wave in Shengli tunnel was tested on site.The propagation and attenuation law of blasting shock wave in highway tunnel was discussed by collecting shock wave shape and overpressure data.The test results are processed by the least square method,and the empirical formula of blasting shock wave in single head tunnel is adjusted to make it more suitable for similar engineering environment.Then,the influence of section change and obstacles on the propagation of blast wave is further analyzed.Combined with the propagation III characteristics of blast wave obtained from numerical simulation analysis,it provides a reference for the safety evaluation and protection of blast wave.