DESIGN OF HYDRO TUNNEL AND SUPPORT SYSTEM

Abstract

This report is prepared as a part of final year project to fulfill the requirement of course syllabus prescribed to Civil Engineering final semester course. We attempt to achieve the level of knowledge and practical understanding required to optimize, design and analyze the support systems in tunnel. The tunnel section was taken as modified horse shape from IS 4880.2.1976 and optimization of tunnel diameter was carried out. The finished optimum diameter was found to be 8.5 m. The tunnel alignment was set and checked for the overburden. Tunnel was found to be safe in overburden check at top of the tunnel. Minimum overburden was found to be 5.735 MPa and maximum was 16.124 MPa. Also, there was found to be enough overburden at crown of the tunnel and cavern of the tunnel. The calculation of vertical stresses and the horizontal stresses was carried out as an input parameter. The respective horizontal stresses were resolved for getting the in-plane stresses and out of plane stresses. For the calculation of horizontal Stresses, different research articles were followed. Maximum stress of 17.74 MPa was found out by Sheorey method and minimum stress of 0.002 MPa was found out by using Terzaghi method. We followed Empirical and Numerical modeling method for the design of the lining. Following Empirical method, the support systems were defined from the Q method, following the Handbook of Q system published by NGI (Norwegian Geotechnical Institute), and comparison between RMR and Q system of Rock Support Classification methods were done following the different charts and table given by the researchers. Here the support systems were found to be different. In accordance to the Rock Support Class from Q System, and researching the input parameters, the design of the lining for tunnel is designed and analyzed using Phase2 8.0 software for required support design. Throughout the section was found to be feasible and safe. After completion of the design and analysis part, cost estimation of the tunnel was carried out. When we calculated the cost estimation, the total construction cost of head race tunnel was found to be approximately Rs. 11 billion