ABSTRACT

The stress induced instabilities are commonly observed in tunneling projects. High in situ stresses can pose challenging and potentially dangerous ground conditions for the tunneling crew and can lag the project completion. There are several factors which contribute to the in situ stress at a site. In areas of very rugged topography, the in situ stress is often subjected to topographic perturbations. In this study the topography along the headrace tunnel in the Neelum Jhelum Hydropower project (Pakistan) is selected for analysis of the topography induced stresses. Digital elevation model of the project site was generated. The 3D real topography model was then run in RS3. The principal stresses magnitudes and orientations were determined by solving the modeled stress tensors. Then the tunnel was simulated under the prevailing rock and stress conditions. Analysis of the results showed failure zone depths consistent with the actual observations in the tunnel.