THESIS ABSTRACT

Abstract

Predicting and verifying dependable rock mass condition is the primary engineering geological issue for any tunnel. In the high Himalayas, it is difficult to predict rock mass by SRT or ERT methods as the tunnel level is very deep, ie; hundreds of meters below the surface and occasionally even more than 1000 m. The discrepancies between the expected rock mass during the geological investigation and in situ geological conditions encountered cause significant problems and delays. This phenomenon also rises in Dordi Khola Hydropower Project. The general objective of this research is to analyze the stability of the tunnel and evaluate the support system using Finite Element Analysis of Headrace Tunnel of Dordi Khola Hydro Power Project. This study analyzed the stability of the critical sections encountered using various empirical and semi empirical approaches as well as numerical modelling for the selected segments of the headrace tunnel and compare the rock support system designed based on explored geology versus the rock support system estimated using Finite Element Method strategies to be adopted to solve the geological problems encountered. From the Block Stability Analysis of the selected sections in the study, it is observed that the wedges that are formed due to the intersection of discontinuities during the tunnel excavation are stable as they develop sufficient Factor of Safety. Similarly, for the sections in which the deformations are observed during the excavation, that are predicted by empirical and semi analytical approach and the support system that are used at the critical section are insufficient to stabilize the rock mass. Hence, to minimize the further damage of the critical sections, the support system are recommended for revision

Keywords

Rock engineering, deformation, squeezing, rock mass, geological parameters,etc.