Study On The Blasting Vibration Control Technology Of New Nearby Tunnel Over-crossing Existing Tunnel

With the rapid progress of traffic construction around our country,the traffic network continues to grow and develop.The number of tunnels is increasing,and the adjacent tunnels are more and more.At present,the drilling and blasting method is still a major construction method of the rock tunnel.When the excavation is excavated,the vibration effect caused by the explosion will inevitably affect the surrounding buildings.How to ensure both the safety of buildings and the efficiency of new tunnels is one of the main contradictions in tunnel blasting.This paper took the Xin'anjiang tunnel on Huangshanpo tunnel of Zunyi City,Guizhou Province as the engineering background.The vibration velocity of tunnel lining was studied from the point of view of blasting stress wave.Through the field test,the optimization of the engineering blasting scheme was optimized and verified.The attenuation law of the tunnel blasting vibration meeting fault fracture zone was simulated by numerical simulation.The main research results were as follows:(1)Using the theory of elastic stress wave,and regarding the inner surface of tunnel lining(initial support or secondary lining)as free surface,velocity thresholds were obtained under different angles of stress wave and different concrete strength.The ratio of the strength of the elastic stress wave in the initial support and the secondary lining was deduced,and the representative conditions were calculated.(2)Based on the numerical simulation software of LS-DYNA,a two-dimensional model of tunnel blasting with fault fracture zone was established.The variation law of velocity waveform of the mass before and after the fault fracture zone was analyzed,and the change process of the vibration velocity of the fault fracture zone was discussed.At the same time,the influence of the characteristics of the fault zone on the blasting vibration was studied,such as the distance from the source to the fault,the thickness of the fault zone and the characteristics of the filling medium.(3)Aiming at the shortcomings of the engineering blasting scheme,the regression analysis of the field test data was used and the vibration velocity threshold was adopted,thus,the relevant measures were taken to optimize the original scheme.Then,the datas of on-site blasting vibration monitoring were analyzed,and the rationality of the optimization scheme was verified.