Research in Long Hole Exploratory Drilling for Rapid Excavation Underground
Final rept. on Phase 2, 25 Jan-1 Oct 1972
JACOBS ASSOCIATES INC SAN FRANCISCO CA
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A method of drilling 1000 foot deep exploratory holes from a tunnel was tested in three quarries. Design data was taken for development of a drill to make a four inch diameter hole underground in moderately strong and high strength rock. A system combining diamond drilling and in-hole percussion drill was successful. Test results showed that the system should be capable of 90 feet of hole per shift in high strength granite and over 150 feet per shift in moderately strong dolomite. A new combination of systems for handling 1000 feet of drill rod entact in a storage pipe and circulating drilling fluid through that storage pipe was very successful. Success was also achieved in handling and preventing some rod failures and in overcoming problems of losses of drilling fluid to the formation. Hole direction problems beyond 300 feet have not been completely solved. Penetration rates of 70 ft. per hour were obtained with a down hole percussion drill in dolomite and 30 ft. per hour in strong granite.
- Mining Engineering
- Civil Engineering
- Machinery and Tools