123. Stability Analysis for Tunnel Using Key Block

A simple block theory approach has been used in this paper to assess block stability in a tunnel and the effect of discontinuities on tunnel wedge stability. Block theory was chosen for the analysis since it provides a simple and quick solution to bestow an understanding the relationship between joint sets forming blocks and support requirements. Computations of predicted unstable block volumes and optimized support forces required to stabilize the rock blocks are discussed here. These computations are dependent on the orientation of emplacement drifts, plunging and shape of the tunnel. This paper deals impinge of orientation on stability of tunnel and analysis the most unstable and venerable key block The different roof bolting permutation and combination has been taken for calculating the factor of safety and the optimum cable bolt has been suggested for safety.