Analysis Of Dynamic Response And Vibration Reduction Of Mountain Tunnel Under Blasting Vibration

With the rapid development of the expressway network,the construction of the mountain tunnel will inevitably encounter special problems such as unfavorable geological condition and similar small spacing tunnel.The blasting vibrations during construction can cause damage to the surrounding rock and structure of the tunnel.Therefore,it is necessary to carry on the analysis and research on the dynamic response of the tunnel under the action of blasting load.This thesis takes the No.1 tunnel in Xiaobei Mountain in Jie Yang to Hui Lai Expressway as the research background.On the basis of the research present situation of the theoretical analysis of rock blasting,the vibration characteristics of the surrounding rock of the No.1 tunnel in Xiaobei Mountain under blasting vibration are studied by monitoring test.The Fourier transform and wavelet packet transform are used to analyze the measured vibration signals in time-frequency analysis to determine the multi-frequency band and its energy distribution characteristics.A simplified method of blasting load combining blasting parameters is applied to the blasting numerical simulation of the No.1 tunnel in Xiaobei Mountain.The distribution characteristics of the three direction vibration velocity along the tunnel axis and the different section of the tunnel under blasting load are analyzed and the blasting vibration intensity is predicted by using the Sadov’s formula.On the basis of the above analysis,the vibration reduction of the blasting load interval time,the influences of different spacing of the tunnel and the fracture zone on the dynamic response of the tunnel are deeply analyzed.The results show that the blasting vibration signal has obvious characteristics of multi main frequency band energy distribution,and the dominant frequency band contains more than 70% of the vibration signal energy.The velocity direction of the crown and the bottom of the arch is vertical,and the velocity direction of the two sides of the arch waist is horizontal.The vibration velocity attenuation index of the same direction in different locations is different.The time interval between 50 ms and 150 ms can satisfy the need of conventional tunnel vibration reduction blasting.The impact of the later tunnel blasting on the former tunnel has been relatively small when the distance between the adjacent tunnels is twice the tunnel width.When the fracture zone is near the surface of the blasting,its influence range is about twice its width,and the vibration velocity increases greatly.