S. Staff. Burnt clay in the vicinity of burnt coal.
An orthorhombic mineral, Cu5 (SiO3 )4 (OH)2 ;
blue.
An orthorhombic mineral, (K,Na,Ba)3 (Ti,Nb)2 Si4 O
14 ; dark brown.
a. A deformation resulting from stresses that cause or tend to cause
contiguous parts of a body to slide relatively to each other in a
direction parallel to their plane of contact. It is the mode of failure of
a body or mass whereby the portion of the mass on one side of a plane or
surface slides past the portion on the opposite side. In geological
literature the term refers almost invariably to strain rather than to
stress. It is also used to refer to surfaces and zones of failure by
shear, and to surfaces along which differential movement has taken place.
AGI
b. See:shearing
c. To make vertical cuts in a coal seam that has been undercut.
Standard, 2
In deep mining fields, shear bursts are the most common type. By the
occurrence of a single shear crack parallel to the face in one of the
walls, the wall rock behind the shear plane is able to expand freely into
the stope, heavily compressing those supports that until then have not
taken stress, throwing still more stress on those that have, and causing
the wall rock between the nearest supports and the face to disrupt and
fill the place with debris. Shear bursts frequently occur at the working
face of a pillar, remnant, or promontory. In such cases, they should not
be mistaken for true pillar bursts. Spalding
A counterweighted refractory slab used as a gate or door to a small
furnace or oven. ASTM
Refers to cleavage where there is displacement of preexisting surfaces
across the cleavage plane by movement parallel to it.
Syn:slip cleavage
A vertical cut made by a special type of coal cutter or arc-shearing
machine. Syn:vertical cut
a. In bituminous coal mining, one who operates a type of coal-cutting
machine that shears (cuts) out a channel down the sides of the working
face of coal (as distinguished from undercutting) prior to blasting the
coal down. Also called shearing-machine operator. DOT
b. A person who operates the shearing machine on a longwall face.
Machine that shears coal or other easily broken mineral from the longwall
face of a seam and delivers the broken material continuously to a
conveying system. Pryor, 3
Failure in which movement caused by shearing stresses in a soil mass is of
sufficient magnitude to destroy or seriously endanger a structure.
Syn:failure by rupture
A fold model of which the mechanism is shearing or slipping along closely
spaced planes parallel to the fold's axial surface. The resultant
structure is a similar fold. Syn:slip fold
A fracture that results from stresses that tend to shear one part of a
rock past the adjacent part. See also:shear joint
CF:tension fracture
a. The vertical side cutting that, together with holing or horizontal
undercutting, constitutes the attack upon a face of coal.
b. Making a vertical cut or groove in a coal face, breast, or block, as
opposed to a kerf, which is a horizontal cut. Called in Arkansas a cut or
cutting. See also:shear
c. Vertical cuts applied in coal headings only to provide an additional
free face, since in heading work it is usual to employ deeper cuts than on
longwall faces, and the shots in headings are much tighter.
McAdam, 2
d. The deformation of rocks by cumulative small lateral movements along
innumerable parallel planes, generally resulting from pressure, and
producing schistosity, cleavage, minute application, and other metamorphic
structures.
A straining action wherein tangentially applied forces tend to produce a
skewing type of deformation. Shear forces are usually accompanied by
normal forces produced by tension, thrust, or bending.
McGraw-Hill, 2
A jib of a coal cutter or cutter loader that makes a vertical or shear cut
in the coal, ore, or rock. Nelson
An electrically driven machine used to cut coal during longwall mining.
Usually used in a double-drum configuration.
ÅW d²s ì³s ú‘A 4 DICTIONARY TERMS:shearing-machine operator See:shearer
[\B]shearing-machine operator[\N]
Joint that formed as a shear fracture. See also:shear fracture
On account of shear strain, the longitudinal tensile or compressive
bending stress in wide beam flanges diminishes with the distance from the
web or webs; this stress diminution is called shear lag. Roark
a. A high wooden frame placed over an engine or pumping shaft fitted with
small pulleys and rope for lifting heavy weights. Zern
b. A tripod on which miners sometimes stand in drilling.
Standard, 2