Study on stability and supporting measures of surrounding rockduring Breakthrough in Deep Highway Tunnel

Abstract

During the construction of the Muzhailing tunnel, the maximum deformation of the surrounding rock was more than 2500 mm. When the tunnel is in the breakthrough stage, more attention should be paid to the danger of large deformation in order to ensure the safety of construction. This paper comparatively analyzed the deformation characteristics and stress distribution of the Muzhailing tunnel surrounding rock under the bolt support and the prestressed anchor cable support by numerical simulation. Then through theoretical analysis, a new method of tunnel support using high prestressed constant resistance and large deformation anchor cable is proposed. The field test results showed that the combination support form of long and short anchor cables with constant resistance and large deformation can improve the stability of the stop working face, and the rock pillar between the working faces, and reduce the influence of excavation disturbance on the surrounding rock of the stop working side. When the tunnel breakthrough construction was completed, the displacement difference of surrounding rock on both sides of the breakthrough position was controlled within 100 mm, and the maximum displacement of surrounding rock was 223 mm. the support method can well control the large deformation of the surrounding rock and improve the stability of the surrounding rock.