Discussion. Present Trends in the Design of Pressure Tunnels and Shafts for Underground.,hydro-Electric Power Stations

Abstract

DiscussionThe Author introduced the Paper with the aid of a series of lantern slides. J. A. Banks said that the Author had presented information ofgreat value to all engineers who were concerned with the design of pressure tunnels and similar works. The Paper was particularly welcome a t the present time, because it was only in very recent years that the construction of underground generating stations had been undertaken in Great Britain. The Author had referred to the Clachan station in Argyllshire and, whilst others had been constructed since or were in hand, it might be relevant to give some particulars of the Clachan works which formed part of the North of Scotland Hydro-Electric Board's Glen Shira project.Clachan generating station, with an inclined pressure shaft (the general arrangement of which was shown in Pigs 30,31, and 32) housed one verticalFrancis turbine of 54,000 horse-power operating under a head of 960 feet.As stated in the Paper, the station had been excavated by the cut-and-cover method. The concrete walls below main floor level had been poured hard against the rock and the reinforced concrete columns and mane girders, which carried a 150-ton overhead travelling crane had been anchored into the rock both longitudinally and transversely. There was an inner lining of brickwork and a suspended ceiling, the main roof having been formed by a reinforced concrete arch springing from skewbacks cut into the rock, and with that internal lining and ceiling there was a complete clearance