Tehri Hydro Development Corporation Ltd.
Four nos. high-pressure shafts, feeding the 4 units of 250 MW each being installed in the underground powerhouse in the first stage of Tehri Project, are steel lined with plates conforming to ASTM A 517 Grade F. The liners are designed to resist internal pressure including water hammer pressure, with due consideration of load transferred to the surrounding rock. Mild steel stiffeners have been provided over the steel liners to resist the external water pressure corresponding to full reservoir level with pressure shafts empty. The paper describes the design criteria adopted for internal and external pressures, rock participations in resisting the internal pressure and additional precautions being taken during fabrication and erection of steel liners.
