DESIGN AND CONSTRUCTION OF * * TUNNELS WIT[' PARTICULAR REFERENCE TO WEAK ROCKS of NAGARJITNASAGAR RIGTIT CANAL TUNNEL"

Abstract

"DESIGN AND CONSTRUCTION OF TUNNELS WITH PARTICULAR REFERPNCE TO !WEAK ROCKS OF NAGARJUNASAGARR RIGHT CANAL TUNNEL" is the subject approved by the Board of Examiners of WtDT CENTRE, University of Roorkee for my dissertation work as a partial ful-fulment of Master of Engineering degree in Water Resources Development. The subject covers a wide range of topics on the investi-gation, design and construction of tunnels in all kind of rocks and with particular reference to weak rocks of Nagarjunasagar Right Canal Tunnel. There are hardly a few books on the above aspects though a number of articles are being punlished periodi-cally on various aspects of tunneling in technical magazines. Hence an attempt has been made in this dissertation work to col-lect all aspects of tunneling work starting from geological In-vestigation to maintenance of completed tunnels. Though the subject is mainly in connection with tunnel-ing in weak rocks, some aspects in hard ground are also discus-sed as most of the tunnels passing through weak rocks are bound. to meet some good Zones where hard rook methods of tunneling are applicable. The importance of geologial survey is stressed giving numerous examples of how faulty and incomplete studies resulted in tunnel hazards, delay and extra cost. Another branch of engineering science, is the Rock Mechanics which is just gain-ing importance in all works connected with rock. This is parti-cularly important In weak rocks and the need and importance of this Rock Mechanics survey is also discussed. . . . 2 The importance of test tunnels in large tunneling works to have a knowledge of type of rocks that will be encountered will facilitate to plan and Resign of works in the main tunnels. The need for suitable instrumentation programme to determine the actual rock loads and deflections in the excavated tunnels during and after completion of work is also discussed. The im-portance of taking up test tunnels in India is also discussed. The subject is dealt in two parts, the first part deal-ing with the design and construction aspects of tunnels in general and the second part dealing with reference to Nagarjuna-sager. Right Canal Tunnel. The recent development in the construction methods, and the modern equipment including machine tunneliig now widely used in large tunnel works in foreign countries are discussed quoting examples of tunnel works that are already constructed are under construction in different parts of the world. The hydraulic design and the structural design which Includes the supporting system like Rock boats; wire mesh; timber and steel supports; lining and grouting, and their advan-tages and disadvantages have been discussed and the detailed calculations of the design of supports and lining of Nagarjuna-sagar Right Canal Tunnel are inc luded. The tunnel hazards due to rook falls which was the main trouble in Nagarjunasagar Right Canal Tunnel is discussed in detail Indicating the steps taken to prevent them. ....3 :: 3 :: The dissertation is ended with a critical study of the aspects of investigation, design and construction of Nagarjuna-sagar Right Canal Tunnel with a few suggestions which it adopted might have resulted In better progress and less cost of the tunnel work.