Execution of large infrastructure projects cannot be imagined without high-level engineering explorations, the prerequisites to increasing the economic efficiency of capital investments. Tehri hydroelectric project is located on the left bank of River Bhagirathi in the state of Uttarakhand. Tehri Pumped Storage Project (PSP) comprising 4 Nos of reversible pump-turbine units of 250 MW each, involves construction of an underground Machine Hall, Upstream Surge Shaft with Chambers-3 & 4, a Butterfly Valve Chamber (BVC), a Penstock Assembly Chamber (PAC), the Downstream Surge Shaft with Chamber-3 & 4, a pair of Tail Race Tunnels (TRTs) and the Outlet structures.
The present paper discusses the innovations made in excavation and support of reverse slope for slanting portion of Upstream Surge Shaft-3 & 4 and also analyses the innovative methods adopted for concrete lining of TRTs.
The paper further describes the series of steps taken to ensure the stability and effective excavation of Tehri PSP U/s Surge-Shafts Slant-portion Design. It also discusses the measures taken to safeguard excavation and support, casting of collar beam and erection of truss girder for gantry movement. Here the focus is on bringing into focus how the invert lining of TRT's done first to be followed by an overt lining. The practice very uncommon in India and sets up a successful example for other industry partners.
Innovation in Tunnelling Technologies in Hydro Project
