Static and dynamic analysis the influence of underlying tunnel construction on surrounding rock of existing tunnel-type anchorages

Abstract Due to the constraints of construction period and site conditions, it is necessary to study the influence of construction of underlying tunnel on the surrounding rock of the existing tunnel-type anchorages. Through static excavation and dynamic blasting, this paper systematically analyzes the influence of underpass tunnel construction on the surrounding rock of the tunnel-type anchorages from the aspects of stress, deformation, plastic zone, velocity and loose circle of the surrounding rock. The results show that the effect of excavation of underlying tunnel on the maximum principal stress around the tunnel-type anchorages is small. The maximum relative displacement of the tunnel-type anchorages is smaller than the allowable relative displacement of the code. The distribution of plastic zone around the tunnel-type anchorages is not affected by the excavation of underlying tunnel. When underlying tunnel blasting, the peak velocity of monitoring points of the top arch in each section of the right underlying tunnel is largest. From the area closer to the explosion source to the far area, the reduction of peak velocity in all directions is large. Based on the elasto-plastic theory, Hoek-Brown strength criterion is used to calculate the thickness of the loose circle.