| Tunneling in the horizontal layer surrounding rock, the excessive and deficient excavation will encountered as the result of geological conditions and constrciton technique. And the interaction effect of the blasting vibration should consider in the construction period when there's small distance between parallel tunnels. And the systematic bolts should also design carefully in the horizontal layer surrounding rock. The following work has done with the method of theory analysis, field test and numerical simulation for the above problems.(1) Several kinds of typical strata and geological structure and failure mechanisms of horizontal layer surrounding rock in Hunan Changji hignway were summarized.(2) Reasons of the excessive and deficient excavation in horizontal layer surrounding rock for soomth blasting were analyzed, and the corresponding measures were constituted.(3) Attenuation law of tunnel blasting vibration was obtained by field test. And the influence regulations of the back-up tunnel blasing construction to the frount tunnel have also analyzed based on numerical simulation. Some contral measures were provided.(4) Mechanism of systematic bolts in the horizontal layer surrounding rock was analyzed. And the axial force of anchor bolts test was performed under different support conditions. Base on the stress characteristics, it is put forward that the anchor bolts on the tunnel sidewall canbe cancelled in the horizontal layer surrounding rock.(5) By carry out monitoring measurement, information feedback, the reliability of tunnel surport structure and construction method and control measure were verified, and the expected goal of construction was achieved. |
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