Challenges of Tunnelling in Debris Dominated Ground: A Case Study from Bangalore City - RT01 / Phase-2

In urban areas, especially in crowded downtown areas, the construction of underground tunnels for public transport is often inevitable owing to the scarcity of land above the ground. In densely populated areas, the tunnels for metro rail and the connecting underground stations are constructed nearer to the existing structures, busy roads and in places with an aim to have easy access to a large traffic that would depend on this facility for its routine commute. The existing geology in Bangalore is intricate in nature, with a combination of mixed ground conditions with the presence of granitic gneiss and boulders in few locations. Tunneling in this kind of geology is adventurous to the Engineers. The uncertainty of geology leads to delay in progress and impacts the overall scenario. This paper presents the hindrances faced during tunneling due to the presence of manmade materials for a certain length and suitable corrective measures adopted according to the site conditions.