Page 17 of 19 First Next Previous Last

UNSTABLE ROCK AND ITS TREATMENT SNOWY MOUNTAINS SCHEME

Treatment:

  1. Wire surface anchors were embedded in clayey material and a layer of mortar 1 to 2 in. thick applied pnuematically.
  2. 17 gauge mesh attached, and long wires attached to this mesh to anchor later mesh.
  3. The slot was filled with pneumatically applied mortar until flush with the wall.
  4. 8 gauge mesh in a strip 6 ft wide was attached by rock bolts, rock anchors, surface anchors, and by wires previously attached to the 17 gauge mesh.
  5. The entire zone was covered with pneumatically applied mortar to a thickness of 1 to 3 in., with a minimum of 1 in. cover over the mesh.
Figure 16

Fig. 16.—Jointed granite, with narrow crushed seams and areas of decomposition. Supported by grouted rock bolts during excavation. Heavy wire mesh pinned by rock bolts, rock anchors and surfaces anchors in preparation for application of pneumatically applied mortar.

All seams of this kind thicker than about ½ in. are treated with pneumatically applied mortar to prevent their erosion. Isolated seams a few inches thick are cut hack to a depth at least equal to their width and backfilled with pneumatically applied mortar. For wider seams the mortar is reinforced with wire mesh.

Light wire mesh was used in seams of moderate width intersecting sound rock which did not require support where protection of the seam against erosion was the only requirement. Heavy mesh was used over seams wider than a foot or so, and where the adjacent rock was closely jointed and required support. Recently the trend in practice has been to use heavy mesh exclusively.

Disintegrating basalt dykes are treated with mortar reinforced with heavy mesh and supported by rock bolts (Fig. 17).

Figure 17

Fig. 17.—Treatment of a disintegrating basalt dyke 1 to 2 ft wide with sheared walls

Broad patches of partially decomposed granite which could disintegrate in water occur both as individual features and in association with sheared zones. These are treated with reinforced pneumatically applied mortar tied to grouted rock bolts.

Broad areas of closely jointed hard strong rock with a tendency to ravel may be treated with plain pneumatically applied mortar.

Details for this article:

Unstable rock and its treatment in underground works in the Snowy Mountains Scheme

X

Author: Moye, D. G (1965)

Article Title: Unstable rock and its treatment in underground works in the Snowy Mountains Scheme.

From: Proc Eighth Commonwealth Mining and Metallurgical Congress, Aust and N.Z. Vol.6 p. 429-441

Other Available Articles

Engineering geology for the Snowy Mountains Scheme

Moye, D.G. (1955)

Engineering geology for the Snowy Mountains Scheme.

J.I.E.Aust., Vol. 27 No.10 pp287–298

Rock Mechanics in the Investigation and Construction of T.1 Underground Power Station, Snowy Mountains, Australia

Moye, D.G. (1958)

Rock Mechanics in the Investigation and Construction of T.1 Underground Power Station, Snowy Mountains, Australia

In Engineering Geology Case Histories No.3 123–54 Geological Society of America 69 (12) p.1617

Existence of high horizontal rock stresses in rock masses.

Moye, D.G. (1962)

Existence of high horizontal rock stresses in rock masses.

Proc. Third Australia-New Zealand Conference on Soil Mechanics and Foundation Engineering. pp 19–22

Seismic Activity in the Snowy Mountains Region and its Relationship to Geological Structures

J. R. Cleary, H. A. Doyle, D. G. Moye (1964)

SEISMIC ACTIVITY IN THE SNOWY MOUNTAINS REGION AND ITS RELATIONSHIP TO GEOLOGICAL STRUCTURES

Journal of the Geological Society of Australia

Unstable rock and its treatment in the Snowy Mountains Scheme.

Moye, D.G. (1965)

Unstable rock and its treatment in the Snowy Mountains Scheme.

Proc. 8th Commonwealth Mining and Metallurgical Congress, Australia & New Zealand. Vol. 6, p. 423–441.

Diamond drilling for foundation exploration

Moye, D.G. (1967)

Diamond drilling for foundation exploration.

Paper 2150 presented at I.E.Aust. Site Investigation Symposium, September 1966. In Civil Engineering Transactions, with Discussion, April 1967.

Geology in Practice

Moye, D.G. (1970)

Geology in Practice. Presidential Address Section 3, Geology, ANZAAS Meeting.

Australian Journal of Science, 32 (12) June, p454–461.

* This paper was presented when Dan had been Director of Exploration of BHP for 3 years.

Field and Laboratory Tests in Rock Mechanics

Alexander, L. G (1960)

Field and Laboratory Tests in Rock Mechanics

Proceedings, 3rd Australian-New Zealand Conference on Soil Mechanics and Foundation Engineering, Sydney Australia, 1960, pp. 161–168.

Discussion at Technical Session No. 9—Rock Mechanics

Alexander, L. G. Moye, D. G. (1960)

Discussion at Technical Session No. 9—Rock Mechanics

Proceedings, 3rd Australian-New Zealand Conference on Soil Mechanics and Foundation Engineering, Sydney Australia, 1960, pp. 254–250