DIAMOND DRILLING FOR FOUNDATION EXPLORATION-Moye
Acknowledgments.
This paper is given with the approval of the Snowy Mountains Hydro-electric Authority. The views expressed are those of the author and not necessarily of the Authority.
References.
- Moye, D. G.—Engineering Geology for the Snowy Mountains Scheme. Jour. I.E.Aust., Vol. 27, No. 10-11, Oct.–Nov., 1955, pp. 287–98.
- Talobre, J.—La Mecanique des Roches. Paris, Dunod, 1957.
APPENDIX.
Talobre (Ref. 2, p. 154) states as an empirical rule that ground is sufficiently impervious for dam foundations or a pressure tunnel, if the rate of water loss from a drill hole 46 to 74 mm. in diameter does not exceed 1 litre/min./m. of hole at a pressure of 10 atm., maintained for 10 min. This rate of loss of 1 litre is defined as one Lugeon Unit. (This is equivalent to 0.067 gal./min./ft. at a pressure of 145 lb./sq. in.) The tests should be carried out on sections 2 m. long.
In the following analysis by M. A. Chapple, the rock is assumed to be homogeneous and isotropic with respect to its permeability and flow is assumed to be laminar.
![appendix math part 1](/images/written_works/diamond_drilling/appendix-1-1.jpg)
If the length of the test section is large compared with the diameter of the hole, flow conditions in the vicinity of the hole are essentially two- dimensional.
![appendix math part 2](/images/written_works/diamond_drilling/appendix-1-2.jpg)
At a distance from the hole which is great compared with the length of the test section, flow conditions are essentially spherically symmetrical in three dimensions.
![appendix math part 3](/images/written_works/diamond_drilling/appendix-1-3.jpg)