Abstract:The form of “squat” section with flat rate in the range of 0.6~0.75 is usually adopted for the traditional mine tunnel, but the flatness ratio of the single-hole double-layer tunnel with the "thin and tall" section form is often greater than 1.0, which exceeds the applicable conditions of the current code. The deformation of surrounding rock and internal force of support in tunnel with high sidewall section are analyzed and studied. The stress and action of anchor rod in the range of high side wall are achieved as follows: (1) The distribution range of surrounding rock plastic zone in the range of high side wall can be effectively reduced, and the stability of surrounding rock can be improved. (2) The horizontal displacement of surrounding rock in the range of high side wall and the bending moment of shotcrete support can be effectively reduced. (3) The tension value of the anchor rod in the middle of the high side wall is the largest, and the tension value of the anchor rod at both ends towards the vault and inverted arch shows a decreasing trend. The on-site monitoring feedback data are used to verify each other. The following conclusion can be drawn from this that the effective "constraint" of tunnel surrounding rock can be formed by setting long and short anchor rods in the range of high side wall, which improves the whole stability and safety of the tunnel. These achievements provide the reference significance for the design and construction of high side wall section tunnels.
