Final Review Quiz_Coal Mining

1.      Interconnection of two levels usually driven from the lower level for ventilation and escapeway purposes:

• cross-cuts

• drifts

• raises

• none of the above

Openings driven from surface crossing different sedimentary formations to intercept the strike of rocks and/or coal seams which usually has a grade of 1% for natural drainage:

• inclined shaft

• vertical shaft

• adits

• all of the above

Goaf means________

• in-situ rock

• caved roof materials

• coal refuse

• powdered coal

Technique to reduce stress concentration at the longwall face

• making the face slightly concave

• making the face slightly convex

• making the face straight

• making the face jagged

It is one of the high-extraction method of mining coal underground.

• longwall mining

• hydraulic mining

• auger mining

• square set

This phenomenon in longwall mining is a result brought about by the violent collapse of the goafs compressing the cavity underneath the main roof. This occurs when the roof is competent (e.g. a massive limestone) and the face has advanced for a distance of 100 – 150 m.

• air blast

• coal bump

• gas burst

• settlement

After the collapse of goaf, a redistribution of the overburden pressure occurs. Part of the load now rests on the goaf and the remainder is partly carried by the ___________.

• roof

• floor

• abutment

• gateroads

A mode of pillar failure wherein the pillar load exceeds the foundation (floor) material’s unconfined compressive strength. The failure is manifested by upward deformation of the floor

• floor squeeze

• floor heave

• floor swell

• floor shear

Another pillar failure mode wherein the coal pillar, due to back pressure, gradually scales off. This effectively reduces the size of the pillar, thereby reducing its strength and increasing the pillar stress.

• slivering

• pillar splitting

• pillar scaling

• roof scaling

A beam failure mode wherein the roof materials break due to its own weight and presence of natural fractures. The roof debris falls into the opening. However, this is not stress-related.

• roof fall

• rock fall

• beam failure

• bending failure