Analysis On Vibration Influence By Blasting Excavation By Numerical Simulation For Existing Tunnel With Small Clearance

In this paper, based on the engineering reference of background lan zhou hub of the newbei huan shan tunnel, which passes on the existing hong shan ding tunnel. The minimumclearance of two tunnels cross section is1.365m, the crossing angle is43.287degrees. Thenew tunnel excavation blasting generated blast will cause vibration impact of certaininstability the existing tunnel lining and the surrounding rock. In this paper, theprinciple-element method is used to analyze vibration influence of tunneling blasting on theexisting tunnel, and some numerical simulations were carried out with LS-DYNA3D programIn the rock and the existing tunnel lining structure got the explosion shock wave of somepropagation, which would provide some references for the numerical analysis andconstruction of the actual engineering. and the follows details are:⑴Firstly, for cross runnel with interval in the process of excavation blasting theproblems are outlined, and proposed research direction and purpose of this article forindividual problems; secondly detailed analyzes and summed up the past10years at homeand abroad, especially in the space cross tunnel of field and tunnel excavation blasting,theChinese scholars and engineers of theoretical calculations numerical simulation results andthe experience accumulated in engineering practice.⑵Describe the mechanism of rock failure and blasting seismic wave generation andpropagation of the way. and for the blasting vibration control standards at home and abroadwere compared and analyzed; but also for the LS-DYAN3D dynamic finite element analysisprogram in the field of numerical calculation explosive impact were elaborated.⑶Blasting from the actual site and the actual control standards starting an analysis ofthe working conditions at the intersection of blasting excavation section of the vibration of theexisting tunnel lining structure, the analysis of existing tunnel lining structure from threeelements begin:①Analysis if the position of the typical variation of velocity of the dome, asa basis for judgment to analyze the existing tunnel blasting vibration by more dangerous areas;②Blasting impact onboththe secondary lining stress distribution in the formof stress wavesgenerated by the time tunnel course were analyzed, and the impact of the regional position byblasting higher sensitivity;③From tensile stress that is a secondary tunnel lining damageperspective sectional analysis of existing tunnel blasting shock wave along the affected archvault to back to yang arch of the variation of tensile stress propagation.⑷Based on different conditions spacing, analyze existing tunnel lining structure ofsecondary impact by the impact of blasting. and got the results of the velocity and stressvariation with spacing, but also got to the critical spacing when blasting step method ofconstruction, at the same time observed the blast wave from the explosion to rock to the holeexisting tunnel lining change over time icon. ⑸Variation of velocity and stress in different rock under the existing tunnel secondarylining were analyzed, from the perspective of the actual construction，analyze unsafeconditions of each of the existing tunnel. At the same time, when away from the intersectionof sections of different pitches of blasting tunnel face, Surface blasting meet along existingtunnel secondary lining of movement law.