Rock mechanics in the investigation and construction of Tumut 1 Underground Power Station, Snowy Mountains, Australia

Plate 6. – Supports Used During Construction (a) Machine-ha1l roof excavation, in the foreground supported by rock bolts only, in the background by rock bolts supplemented with steel supports. Triangular overbreak on right side of roof is site of rock fall caused by intersection of minor fault A and joint of set b. (b) Transformer hall, 72 feet wide, with rock bolts only as support.

Plate 7. – Excavation of the Machine Hall (a) First stage of excavation at the end of the machine hall in granite. (b) Machine hall during construction, showing concrete ribs for permanent support.