SYMPOSIA PAPER Published: 01 January 1979
STP35817S

Mechanism of Fracture of Hard Rock Using a Drag Bit Assisted by Waterjets

Source

It is shown that the mechanism of rock fracture is similar both when a blunt drag bit is used to cut strong rock and when a flat-bottomed punch is pressed into the rock surface. In order to study this fracture mechanism an experimental technique was developed which involved indenting the rock specimen in a quasi-static manner, using a drag bit as the punch. The effect of directing waterjets adjacent to the bit was investigated and it was found that these jets caused a rock chip to form with lower than normal forces applied to the bit. This finding agrees with results of previous experiments where lower forces were applied to the bit during the cutting operation when waterjets were used. A hypothesis is proposed to explain the action of the waterjets on the rock to produce this reduction in the indentation force.

Author Information

Hood, M
University of California, Berkeley, Calif.
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Details
Developed by Committee: G02
Pages: 553–561
DOI: 10.1520/STP35817S
ISBN-EB: 978-0-8031-4737-9
ISBN-13: 978-0-8031-0334-4