STABILITY OF TUNNEL SUPPORT SYSTEMS IN A POOR ROCK MASS

Abstract

Design of tunnels in a poor rock mass becomes challenging task in tunnelling technology because improper support system design can leads to large scale failures. Several approaches have been used for design of support systems for tunnels excavated in poor rock. In present work tunnel deformation has been studied through numerical methods and analytical methods. The interaction of the recommended support systems by analytical methods with different ground conditions were analyzed by two dimensional universal distinct element code (UDEC). In this thesis a HRT tunnel of 23.5 km long and 5.4 m diameter, coming under the influence of both Kashmir Napppe and Indus techno-stratigraphic zone is analyzed. Typical squeezing ground sections were taken in consideration and analyzed with both numerical methods and closed form solutions. The suitable support system is suggested for the tunnel determining the equilibrium pressure and deformation. Finally the deformations obtained from UDEC analysis for each section has been compared with results obtained from closed form solutions.