Rock burst
Encyclopedia
A rock burst is a spontaneous, violent fracture of rock
that can occur in deep mines
. The opening of a mine shaft relieves neighboring rocks of tremendous pressure, which can literally cause the rock to explode
as it attempts to re-establish equilibrium. Rock bursts are a serious hazard; in South Africa
, they kill roughly 20 miners each year.(Monroe and Wicander, 96) Rock bursts basically depend on the size and depth of the excavation.
, deriving from the strain energy produced by its geological aspects.
The likelihood of rock bursts occurring increases as depth of the mine increases. Rock bursts are also affected by the size of the excavation (the larger the more risky), becoming more likely if the excavation size is around 180 m and above. Induced seismicity
such as faulty methods of mining can trigger rock bursts. Other causes of rock bursts are the presence of faults
, dykes
, or joints.
Rock (geology)
In geology, rock or stone is a naturally occurring solid aggregate of minerals and/or mineraloids.The Earth's outer solid layer, the lithosphere, is made of rock. In general rocks are of three types, namely, igneous, sedimentary, and metamorphic...
that can occur in deep mines
Mining
Mining is the extraction of valuable minerals or other geological materials from the earth, from an ore body, vein or seam. The term also includes the removal of soil. Materials recovered by mining include base metals, precious metals, iron, uranium, coal, diamonds, limestone, oil shale, rock...
. The opening of a mine shaft relieves neighboring rocks of tremendous pressure, which can literally cause the rock to explode
Explosion
An explosion is a rapid increase in volume and release of energy in an extreme manner, usually with the generation of high temperatures and the release of gases. An explosion creates a shock wave. If the shock wave is a supersonic detonation, then the source of the blast is called a "high explosive"...
as it attempts to re-establish equilibrium. Rock bursts are a serious hazard; in South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
, they kill roughly 20 miners each year.(Monroe and Wicander, 96) Rock bursts basically depend on the size and depth of the excavation.
Details
Rock bursts are the result of brittle fracturing of rock, causing it to collapse rapidly with violent expulsion of rock that is approximately 100 to 200 tonnes, or more. This release of energy reduces the potential energy of the rock around the excavation. Another explanation is that the changes brought about by the mine's redistribution of stress trigger latent seismic eventsEarthquake
An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. The seismicity, seismism or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time...
, deriving from the strain energy produced by its geological aspects.
The likelihood of rock bursts occurring increases as depth of the mine increases. Rock bursts are also affected by the size of the excavation (the larger the more risky), becoming more likely if the excavation size is around 180 m and above. Induced seismicity
Induced seismicity
Induced seismicity refers to typically minor earthquakes and tremors that are caused by human activity that alters the stresses and strains on the Earth's crust. Most induced seismicity is of an extremely low magnitude...
such as faulty methods of mining can trigger rock bursts. Other causes of rock bursts are the presence of faults
Geologic fault
In geology, a fault is a planar fracture or discontinuity in a volume of rock, across which there has been significant displacement along the fractures as a result of earth movement. Large faults within the Earth's crust result from the action of tectonic forces...
, dykes
Dike (geology)
A dike or dyke in geology is a type of sheet intrusion referring to any geologic body that cuts discordantly across* planar wall rock structures, such as bedding or foliation...
, or joints.