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. [1] 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.

Meeting Name

41st U.S. Symposium on Rock Mechanics, USRMS (2006: Jun. 17-21, Golden, CO)


Geosciences and Geological and Petroleum Engineering

Second Department

Mining 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

Document Type

Article - Conference proceedings

Document Version


File Type





© 2006 American Rock Mechanics Association (ARMA), All rights reserved.

Publication Date

01 Jun 2006

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