Research On Structural Vibration Response And Millisecond Time Optimization Caused By Blasting Underpass Tunnel

This paper is Based on the engineering example of a subway tunnel in kuanzhou District of Changchun City,through the numerical simulation method,the joint model of superstructure,stratum and blasthole is established firstly,and through the study of the peak value of the vibration velocity of the superstructure,the change rule of the structure node and the position relationship with the blasting source are obtained;on this basis,the four hole cut blasting is established by referring to the actual blasting parameters In the model,eight groups of differential time are set respectively,and the most suitable differential time is obtained by analyzing the vibration velocity of the top node of the tunnel.The results are as follows:(1)After the detonation of the explosive source,the internal energy of the energy is rapidly converted into kinetic energy and propagated outwards,and the energy decays rapidly;the vertical velocity the horizontal radial velocity the node at the explosive source change rapidly,and the node vibrates and decays rapidly;the horizontal tangential velocity changes slowly,and the node velocity decays slower than the other two directions.(2)Under the action of single section blasting,the peak vibration velocity along the x-direction of the peak value of the superstructure node decreases first and then increases with the increase of the distance from the blasting source,while the peak vibration velocity along the x-direction of the peak value increases first and then decreases with the increase of the distance from the blasting source.And the change rule of peak velocity has nothing to do with the change of floor height.(3)The peak value of vertical velocity the joint of superstructure is larger than that in the other two directions.With the increase of floor height,the peak value of seismic velocity in the three directions first decreases,and then suddenly enlarges in the top layer.(4)Through the numerical simulation study,the four cut blasting adopts the millisecond blasting,the millisecond blasting can effectively reduce the vibration speed of the rock mass medium and improve the harm brought by the blasting;when the millisecond time of the cut is set to 15 ms in this project,the peak vibration speed of the rock mass medium at the top of the tunnel is 67.5% lower than that of the four hole blasting.