Study On Optimization Of Blasting Scheme In Horizontal Layered Surrounding Rock Tunneling

All kinds of complex engineering geological environment is not uncommon,whenhighway tunnel through a variety of mountain terrain. Especially，when the tunnelthrough the layered rock, the tunnel excavation contour is easy to form a rectangularshape After blasting,at the same time，it appears different degree of impellers, and evenproduce the adverse factors of construction, This situation makes a greatdeviationbetween the actual excavation contour and the design of contour.Researchoptimal blasting parameters scheme, so that the actual excavation contour and thedesign of contour matches well under the layered soft rock geological conditions,Reducing overbreak as much as possible.After blasting the stability of the tunnel dependslargely on the nature of the rockmass in different geological structure, spatial variation and the degree of blasting effecton the geological structure at the process of the tunneling.Research and analysis thetunnel stability in layered rock under the blasting impact of dynamic effects，it isbeneficial to improve tunnel blasting construction technology and safety in theconditions of layered weak rock geological. Particularly, the effect is moresignificantwhen the tunnel through the weak intercalation layers and the blasting holethrough the weak intercalation layers, after the blasting between the design of tunnelcontour-line and stability. Therefore, it is an urgent to solve this new task whichresearch the impact of dynamic effects between the design contour-line and tunnelstability,meanwhile, it isthe focus topic of Rock Mechanics and Blasting Engineering.In this paper，applying the Explosion and ShockDynamics，in theoretical view ofoptimized the layered weak rock tunnel blasting parameters under the geologicalcondition. Application of the theory of Fluid Dynamics and Gas-liquid two phase flow,analysis the movement under the blasting process of weak intercalations, and establishthe process of the blasting mechanics analysis model in weak intercalations.UsingANSYS/LS-DYNA3D dynamic finite element analysis program for numericalsimulation, to study the layered weak rock surrounding geological conditions at thedifferent holes and control，column length and diameter ratio on the change rule andinfluence of tunnel excavation contour.By researchon layered rock tunnel under blast loading destruction, propose areasonable optimization schemeat layered rock tunnel blasting,Through numerical simulation obtained the following results:①This paper has been optimized layered rock tunnel blasting scheme, proposedlayered rock tunnel blasting technique which using a half-pipe or boreholes installedcombined with electronic detonators.②This paper calculated five layered rock tunnel blasting scheme, analysis andcomparison of five blast optimal case in the plastic zone and the forces after blasting,Achieved the best solution to optimize the layered rock tunnel blasting.③Analysis and comparison of five blasting scheme, the best solution will be usedby the blast hole layout, loading dose and half-pipe blasting technology or boreholeblasting with combining electronic detonators, the idea of extended to similarly layeredrock tunnel blasting excavation.This idea can be extended to similarly layered rocktunnel blasting excavation process.