Study On Vibration Law Of Small Spacing Tunnel Blasting Near Area Jing-Zhang High-speed Railway Station

At present,the research on the influence of blasting vibration on the structural safety and surrounding rock stability of tunnel is mainly limited in the far area of blasting.Even the Sadov’s formula of given in the blasting safety regulations is only in accordance with the actual measured data in the far area of blasting.In order to guide the construction of the tunnel close to the existing buildings,the problem that there is no formula to predict the vibration speed in the near area of blasting is solved.This paper mainly does the following work:(1)Through the dimensional analysis in the theoretical analysis and research,a new blasting vibration law model with more factors considered in the classical Sadov’s formula is obtained.(2)In this paper,the vibration velocity in the near blasting area of the small spacing tunnel in Badaling station of Beijing Zhangjiakou high speed railway is measured,and the data of the vibration velocity of the surrounding rock blasting 50 meters before and after the blasting position of the face is obtained.The geological and hydrological conditions and rock properties of the project are investigated,and the blasting parameters of the explosive are designed.The vibration law of Sadov’s formula form and new formula model of surrounding rock near the blasting area are obtained by regression fitting of influencing factors of monitoring data,and the vibration law of near blasting area of Beijing Zhangjiakou high speed railway tunnel is revealed.By comparing the two kinds of laws,the new law is closer to the reality,and more suitable for the prediction of blasting vibration in the near area.(3)In order to further clarify the impact factors of blasting and reduce the impact of random error,this paper uses the ANSYS LS-DYNA finite element software to simulate the blasting process of tunnel,and obtains the vibration laws of two models in the near zone of blasting under the condition of numerical simulation.The new formula is still closer to the monitoring data than the classical formula,and better than the actual project.(4)Based on the superposition principle,the vibration law in the near zone of tunnel blasting is further revealed.This paper expounds the process of linear and nonlinear superposition,compares the difference between linear superposition principle and nonlinear superposition principle,analyzes the advantages and disadvantages of the two kinds of superposition models,and puts forward a modified nonlinear extended proportional charge superposition model.Different models are used to compare the superposition effect with the actual effect,which verifies the effectiveness of the proposed model in the actual project.