Disc Cutting of Low-Strength Brittle Rock
Disc cutters are designed to fragment hard, brittle rock (UCS 60-200 MPa). The most energy-efficient mechanism requires the cutter to penetrate the rock to the critical depth required to initiate chipping. In hard, brittle rock the critical depth is relatively shallow (less than 13 mm); deeper penetrations are difficult to achieve reliably. Using disc cutters in very soft rock results in plowing rather than chipping. However the intermediate class -- brittle enough to chip yet weak enough for deep penetration -- has not been fully explored. This paper reports on a series of laboratory tests in which a 292mm-diameter constant cross-section disc cutter was applied to a soft limestone (UCS 14.2 MPa) and a weakly cemented sandstone (UCS 25.5 MPa) at ratios of cut spacing to cutter penetration (S/P) from 6 to 36. Snowdon et al.  predict optimal fragmentation at S/P ratios of one to five for rock in this strength range; although modern practice tends toward higher ratios, little data is available for high-S/P ratio, deep-penetration cutting of low-strength rocks. Cutting tests completed to date indicate that deep penetration coupled with wide spacing at moderate S/P ratios may be more effective in the rocks tested.
L. S. Gertsch and D. A. Summers, "Disc Cutting of Low-Strength Brittle Rock," Proceedings of the 41st U.S. Symposium on Rock Mechanics (USRMS): "50 Years of Rock Mechanics - Landmarks and Future Challenges." (2006, Golden, CO), American Rock Mechanics Association (ARMA), Jun 2006.
41st U.S. Symposium on Rock Mechanics, USRMS (2006: Jun. 17-21, Golden, CO)
Geosciences and Geological and Petroleum Engineering
Mining and Nuclear Engineering
American Rock Mechanics Association
Keywords and Phrases
Brittle Rocks; Critical Depth; Cutting Test; Deep Penetration; Disc Cutter; Energy Efficient; Laboratory Test; Optimal Fragmentation; Soft Rocks; Cutting; Energy Efficiency; Rock Mechanics
Article - Conference proceedings
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