Study On Blasting Vibration Propagation And Partition In Super Large Section Small Spacing Tunnel

With the rapid development of China’s economic construction,the country’s demand for transportation infrastructure construction continues to increase.The multi-lane intercity expressway that appeared in the spring bamboo shoots is in urgent need of a large number of tunnel projects,and the super large section small-spacing tunnel that can guarantee the traffic speed of vehicles has won quite a lot of favor.In the construction process of the super large section small-spacing tunnel constructed by the drilling and blasting method,the subsequent blasting construction of the tunnel must inevitably respond to the blasting of the structure of the preceding hole,which affects the structural safety and stability of the preceding hole.Based on the Daling tunnel project of the south extension line of Jinan Ring Expressway,this paper uses on-site monitoring measurement and three-dimensional dynamic numerical simulation to study the blasting seismic wave propagation law and the blasting vibration response of the preceding tunnel during the construction of the subsequent tunnel blasting.The effects of different surrounding rock parameters and different blasting design parameters on the blasting vibration of the leading tunnel were discussed.The vibration velocity prediction equation was proposed with the main influencing factors as the independent variables,and the zoning method of the adjacent tunnel blasting vibration was proposed.The main research contents and results are as follows:(1)The numerical analysis model of blasting vibration of super large section small-spacing tunnel is established.The propagation law of blasting seismic wave in surrounding rock is calculated and compared with the empirical formula of Sadowski.The stress state and vibration velocity of the supporting structure of the leading hole are analyzed.According to the distribution law,it can be seen that the vibration response on the explosion side is the strongest,and the most dangerous part is located on the side wall of the explosion side 5 to 10 m in front of the face of the face.(2)Numerical simulation analysis of different values of different surrounding rock parameters by single variable method shows that the bulk density,elastic modulus,cohesion force and blasting vibration intensity are negatively correlated,Poisson’s ratio is positively correlated with blasting vibration intensity,among them,elastic mode The amount has a great influence on the blasting vibration intensity.(3)Through the single variable method,the numerical simulation analysis of different values of different blasting design parameters is carried out.It is found that explosive detonation velocity,charge density,single footage and blasting vibration intensity are positively correlated,and explosive detonation velocity and single footage have great influence on blasting vibration intensity.Large,and the rise and fall time has little effect on the blasting vibration intensity.(4)The uniform design method was used to design the experimental scheme for numerical simulation.The prediction formula of the lining vibration velocity based on the four parameters of tunnel clearance,charge,explosive detonation velocity and surrounding rock elastic modulus was obtained,and the vibration velocity partition threshold value of blasting vibration was proposed.The evaluation method of blasting safety based on vibration velocity prediction formula and partition threshold is proposed.In the future,blasting prediction and design guidance can be carried out for similar projects.