Study On Blasting Control Technology For Adjacent Construction Of Large Section Highway Tunnel And High Speed Railway Tunnel

In recent years,the process of traffic construction in China is accelerating,and the road traffic network is constantly improving,which leads to more and more problems in the construction of adjacent projects.The probability of meeting between the new tunnel and the existing tunnel is increasing,and the approach conditions are more and more complex.There are horizontal parallels between new tunnels and existing tunnels,as well as three-dimensional crossings and overlaps.When the mining method is used to excavate the tunnel near the existing tunnel,the stress wave generated by blasting will have a certain impact on the safety and stability of the existing tunnel.Therefore,how to ensure the smooth construction of the new tunnel and reduce the dynamic response of the existing tunnel has been a hot and difficult problem in the academic and engineering circles.This paper is based on the intersection of Xizengshan tunnel of Yidong Expressway and Wuwu tunnel of Hangzhou-Wenzhou high speed railway.By using the methods of data investigation,theoretical analysis and numerical simulation,the influence law and control measures of blasting construction of new tunnel on existing tunnel are studied systematically and deeply.The main research contents and achievements are as follows:(1)Based on rock blasting mechanism,propagation law of stress wave and wave dynamics theory,the influence of blasting stress wave on tunnel lining structure vibration is analyzed,and the influencing factors of blasting vibration of adjacent tunnel are summarized.(2)Based on the stress wave theory and material ultimate strength criterion,a prediction model of blasting vibration velocity based on the safety of tunnel lining structure is established.According to the calculation results of the criterion model and referring to the existing blasting vibration criterion standards at home and abroad,the safety evaluation method of the adjacent tunnel under blasting vibration is established,and the influence partition standard of the blasting vibration of the adjacent tunnel is proposed.(3)Combined with large cross-section double-track highway tunnel engineering,the calculation models of different surrounding rock grades(III,IV,V)and different clear distances(5m,10 m,15m,20m)are established by using ANSYS/LS-DYNA software.The dynamic response law of the lining structure of the first tunnel under the blasting load of the second tunnel is explored.Based on the safety evaluation standard of blasting vibration and the distribution characteristics of vibration velocity and stress of tunnel lining structure,the influence partition of blasting vibration for the first tunnel is proposed based on the surrounding rock grade and tunnel clear distance.(4)Combined with the crossing project of high-speed railway tunnel and expressway tunnel,the calculation models of different blasting positions are established by using ANSYS/LS-DYNA software.Through the whole process simulation of the blasting excavation of the tunnel in the crossing section,the dynamic response characteristics of the existing tunnel structure in the cross section and the axial direction are analyzed.At the same time,the influence law of blasting vibration when the high-speed railway tunnel crosses the existing expressway tunnel is summarized,and the blasting vibration influence partition of the existing expressway tunnel based on the distance between the excavation face of the new tunnel and the center of the intersection section is proposed.(5)Aiming at the key influence area of the new tunnel and the existing tunnel in the process of approaching,the influence of the damping hole on the blasting vibration effect is studied.By analyzing the law of particle vibration velocity and vibration reduction efficiency under the conditions of different diameter,spacing,position and row number of damping holes,the relationship between vibration reduction effect of damping holes and their specific parameters is established.After that,the damper hole is applied to the small clear distance section of Xizengshan expressway tunnel,which proves that the damping hole has good vibration reduction effect and can provide certain scientific guidance for practical engineering project.