Study on the Influence of Dip Angle of Strata on the Bearing Stability of Tunnel-Type Anchorage

To study the influence of dip angle of layered strata on the bearing characteristics and stability of tunnel-type anchorage, the geological model of tunnel-type anchorage under typical dip layered strata is generalized through case analysis. The influence of dip angle of strata on the displacement of plug body, the development of deformation and plastic zone of surrounding rock, the stress distribution of interface between the plug body and rock mass are systematically discussed by numerical analysis method. The results show that: The axial displacement of the plug body and the plastic zone of surrounding rock after failure are the largest when the rock stratum inclination is 30°, which has the greatest influence on the bearing stability of the tunnel-type anchorage. When the dip angle of rock stratum is 70°, the tunnel-type anchorage tends to rotate counterclockwise under the design load, which will lead to the existence of unconfined area on the crown of the back face of the plug body. Simultaneously, the normal stress of the interface is zero. The greater the dip angle of rock strata, the greater the fluctuation of the isoline of principal stress of surrounding rock due to the dislocation resistance between rock strata. When the dip angle of rock strata is greater than the dip angle of plug body, there will be no concentrated compression ring of plug body. The research results can provide reference for the construction design and stability control of tunnel-type anchorages in layered strata.