Research On The Blasting Vibration Model Of The Nearby High-speed Railway Tunnel And The Drilling And Blasting Technology Of The Newly-built Tunnel

In the process of high-speed railway construction,it often occurs that a new tunnel or two parallel tunnels are excavated in parallel next to the existing high-speed railway tunnel.The blasting excavation of the new tunnel is easy to cause vibration damage to the adjacent existing tunnel and affect the safety of the existing tunnel.How to control blasting vibration so that the new tunnel can not only meet the safety requirements of existing high-speed railway tunnels,but also meet the economic and rapid construction is the focus of high-speed railway tunnel construction.Based on four single-hole double-track high-speed railway tunnels in Duyun Section of Guinan Railway,the No.1 and No.2 new Duyun tunnels,No.1 and No.2 new Bajiaochong tunnels,the blasting vibration model of the high-speed railway tunnel and the drilling and blasting technology of the new tunnel were studied by using the field test data,statistics and optimization theory,numerical simulation and theoretical analysis.The main research contents and results are as follows:(1)Based on the field blasting vibration test data,five kinds of blasting vibration velocity prediction models were established based on Sadov’s formula fitting,Support Vector Machine(SVM),Least Square Support Vector Machine(LSSVM),Particle Swarm Optimization Least Square Support Vector Machine(PSO-LSSVM)and Grey Wolf Optimization Least Square Support Vector Machine(GWO-LSSVM).The vibration response of the existing tunnel lining structure under the action of the blasting construction of the adjacent tunnel was studied,and found out a set of feasible prediction models for the blasting vibration response of the existing tunnel,which provided a theoretical basis for the blasting vibration prediction,and the selection of reasonable and feasible blasting scheme and control blasting measures of similar projects before construction in the future.(2)By comparing the prediction results of Sadov’s formula fitting,SVM,LSSVM,PSO-LSSVM and GWO-LSSVM,the GWO-LSSVM prediction model is the best in terms of convergence speed,solution precision and generalization ability,which is used to guide tunnel blasting construction.(3)Based on Technical specification for blasting vibration safety of railway engineering and Blasting safety regulations,the safety control standards for the blasting vibration of the lining and catenary pillars of the existing high-speed railway tunnel in the construction of new tunnels by drilling and blasting are determined as follows: the maximum particle vibration velocity less than 5 cm/s is the blasting vibration safety allowable value of the lining structure of the existing high-speed railway tunnel,and the maximum particle vibration velocity less than 4 cm/s is the blasting vibration safety allowable value of the catenary pillar base of the existing high-speed railway tunnel.(4)Based on the four new tunnel projects of Guinan Railway in Duyun City,Guizhou Province,which are close to the existing high-speed railway tunnels.The influence of blasting construction of the new tunnel on the vibration of lining structure and catenary pillar of the existing high-speed railway tunnel was studied by numerical simulation under the conditions of spacing of 25 m,30m,40 m and 60 m respectively.The blasting vibration response of the existing tunnel under different tunnel spacings when using the step method in the construction was studied,and the application of the vibration damping technology of electronic detonator in the construction of near tunnel was studied.The research results can provide reference for drilling and blasting technology of new tunnels near high-speed railway tunnels.(5)The PSO-LSSVM and GWO-LSSVM blasting vibration velocity prediction models were used to compare and analyze the numerical simulation results.The average relative error of the predicted blasting vibration velocity of the two models is 12.95 %and 11.99 %.It shows that the PSO-LSSVM and GWO-LSSVM prediction models have high accuracy in the process of tunnel blasting construction,and have important reference significance in the prediction of blasting vibration velocity.