G.B.Nagendra. General Manager - Projects, Konkan Railway Corporation, gives a first-hand experience of the adverse geological conditions encountered during construction of Tunnel T5 of the Katra-Dharam Section of the USBRL Project and the solutions that were adopted.
Tunnel T5 of the Katra-Dharam Section of the Udhampur-Srinagar-Baramulla Rail Link Project in the Himalayan region of India witnessed several geotechnical challenges during the course of its construction. Most of the 6-km long tunnel was constructed using the New Austrian Tunneling Method (NATM). Several challenging ground conditions were encountered - from sheared rock mass to visco-elasto-plastic stratum. Water gushes were also encountered. This article presents two short portions of the Main Tunnel between CH 44+500 to 44+525 comprising of a complicated arrangement of a shear zone sandwiched between dolomite rock mass, fully charged with water, which repeatedly flooded the tunnel in September 2015 and between CH 48+654 to 48+636 where water-bearing sirbon dolomite was sandwiched with shale.