Evaluation on Influence of Pre-Installed Cable Bolts on Stability of Tunnel and Support Effect of the Cable Bolts

Abstract

In this paper, based on the measuring result on axial force of support members (rock bolts and cable bolts) and displacement of tunnel crown and side wall, evaluation on pre-reinforcement effect and support effect of pre-installed cable bolts during enlargement was carried out.
As a result of the examination, following fact clarified. 1) The stability of the ground around the tunnel was improved by axial force arises in pre-installed cable bolts. 2) There is effect of decreasing of crown settlement and convergence in pre-installed cable bolts. 3) It was possible to use the cable bolting system as a supporting member in the main tunnel.