Damage Evolution Analysis And Safety Evaluation Of The Adjacent Structure By Urban Tunnel Blastig Vibration

In recent years,China's infrastructure construction is booming,many cities began to vigorously develop underground traffic to ease the ground traffic pressure,it is inevitable that underground tunnels of the central city which densely populated and complex buildings were excavated.Under the comprehensive index of economy and efficiency,the drilling and blasting method is still the most widely used method in the construction of rock tunnel.The proper use of blasting will produce good returns,improper control will produce many hazards,especially for city tunnel blasting,blasting may endanger the safety of the residents to the ground or make buildings damaged by tunnel excavation,resulting in different degree of influence on the ground environment.In order to explore the influence of tunnel blasting vibration on the adjacent buildings on the ground,in this paper,based on the theoretical analysis,field monitoring and numerical simulation,the characteristics of blasting vibration,the influence factors of blasting vibration and the dynamic response characteristics of buildings under the action of blasting vibration(Stress,displacement,shock velocity,etc.)are analyzed and discussed It aims at combining theory and practice,based on the finite element numerical simulation to predict the safety evaluation of building guidance reference for actual construction.The main research contents and results are as follows:(1)The mechanism of the blasting ground motion,the focal mechanism and the influencing factors of the blasting vibration intensity are described in detail.It is clear that the action of blasting ground motion is in a certain range,and the calculation method and application standard of the partition radius of blasting vibration are analyzed.(2)This paper analyzes the earthquake damage mechanism of the building(structure),and introduces the equivalent method of building(structure)under the dynamic analysis.Based on the classical dynamics theory,this paper studies the structure of the building dynamic analysis of the theoretical method under blasting vibration,detailing the blasting vibration eigenvalue,damping and time history analysis method.(3)Based on the finite element model,the time dynamic analysis method is used to calculate and analyze the dynamic response of buildings under three different bursting distance conditions.In this paper,the dynamic response of buildings with structural conditions,stress and shock velocity is summarized.In general,the dynamic response indexes of buildings are in accordance with the relevant regulations.At the same time,it is proposed that the seismic vibration is a reasonable basis for the safety evaluation of buildings under blasting vibration.(4)Through the numerical simulation,the author verifies the existence of "magnification effect" and "hole effect",and it is necessary to strengthen the vibration monitoring of the ground floor of the excavated tunnel when the building height may be damaged due to the double effect.(5)The Fourier transform analysis method was used to analyze the measured and simulated data,The spectrum and frequency distribution of the blast wave are studied.to analyze the influence of blasting vibration on the building The BP neural network is also used to provide a seismic velocity prediction model for the project.