Effect of Discontinuity Orientation and Geological Overbreak in Tunnels: Case study of Tunnel T 74 R (A) 1

Abstract: Tunnel Stability is affected by so many factors. These may include Rock Quality Designation, Rock Strength, Groundwater Conditions, Vertical rock Cover or Overburden and Discontinuity or joints Conditions. This paper is going to encompass effects of Geological parameter ‘Discontinuity Orientation’ which is commonly used to Calculate RMR Value in Tunnels. This factor affects the stability of the Underground structure. But its impact on time and money is also seen. Various preventive measures to mitigate discontinuity induced Geological over breaks is also discussed in this paper with special reference to Tunnel T-74 R (Section of Udhampur-Srinagar-Baramulla-Rail Link) between KM 127.660 to KM 130.950.This paper is helpful for those who are executing tunnels in foliated and bedded rock mass.