Study On Stability And Blasting Control Technology Of Tunnel In A Horizontal Rock Mass

Due to the influence of the structural surface,the blast energy cannot be fully utilized during the tunnel blasting excavation of the layered rock mass.The reason for the loss of blasting energy due to blasting along the surface of the weak structure.Moreover,if the construction process is not handled properly,there will be a large range of flat roofs,missing blocks,and landslides on the vault of the tunnel.Because of the poor effect of smooth blasting,it not only affects the stability of the surrounding rock of the cavern,but also causes excessive overbreak and overbreak.In addition,increase the amount of engineering and construction investment for the initial support and secondary lining.Therefore,it is of great engineering significance to study the effect of horizontal joints on the stability of tunnels and to improve and perfect the horizontal layered surrounding rock blasting technology.This is to ensure the safety of tunnel construction and improve the stability of surrounding rock and save project cost.In this paper,the following research was conducted on the background of the Zhaocunpu Highway Tunnel on the Taihang Mountain Expressway.(1)UDEC discrete element analysis software is used to combine,analyze,and compare the effects of different rock layer thicknesses and strengths of different structural planes on the stability of tunnels.The following conclusions are drawn that Horizontal arches tend to occur at locations where the arches are perpendicular to the structural plane(vertical direction).Also,with the decrease of the joint pitch and the reduction of the strength of the structural plane,the bending damage is more likely to occur.(2)The single hole blasting of intact rock mass and jointed rock mass was compared and analyzed by finite element dynamic analysis software ANSYS/LS-DYNA.The process characteristics of single hole rock blasting and the effect of joints on the propagation of stress waves and the extension of cracks are obtained.(3)Numerical simulation and analysis of double-hole blasting of rock mass with different joint pitches by finite element dynamic analysis software ANSYS/LS-DYNA.Through the adjustment of rock blasting parameters,the through-hole cracks between the holes are of good quality to determine a reasonable hole spacing and charge volume.Comparing the effects of different joint spacings on the penetration of two-hole blasting.The results show that the smaller the joint spacing,the more obvious the barrier effect on the stress wave and the more detrimental to the blasting effect.