Rock fragmentation mechanisms induced by a drill bit

• In most of the mechanical excavation methods the fundamental process is indentation of the rock by a bit. The present paper focuses on discussing how the rock is fragmented under the action of a drill bit. The discussions are mainly based on numerical modelling using the rock and tool interaction code (R-T2D) and taking rock heterogeneity into consideration. The simulated results concerning rock penetrations with one, two and multiple indenters are, however, compared with experiments available from the literature. The emphasis is put on discussion of the formation of side-cracks and crushed zones that constitute the major rock removal fractures. The agreement between numerical simulation and experimental observations are reasonably good. This reveals the mechanisms of crack initiation, propagation and coalescence induced by the action of button bits to form the rock fragmentation in a drilling process. The investigation can contribute not only to improving percussive drilling but also to understanding other rock fragmentation and comminution methods and equipment since indentation is also the fundamental process for them.

Subject headings

TEKNIK OCH TEKNOLOGIER  -- Samhällsbyggnadsteknik -- Annan samhällsbyggnadsteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Civil Engineering -- Other Civil Engineering (hsv//eng)

Keyword

rock drilling

fragmentation

heterogeneity

numerical simulation

side crack

crack coalescence

Mining and Rock Engineering

Gruv- och berganläggningsteknik

Publication and Content Type

ref (subject category)

art (subject category)