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Rock Outburst
A rock burst is a spontaneous, violent failure of rock that can occur in high-stress mines. Although mines may experience many mining-related seismic events, only the tremors associated with damage to accessible mine workings are classified as rock bursts. The opening of mine workings relieves neighboring rocks of tremendous pressure, which can literally cause the rock to explode, or trigger abrupt movement on nearby geological structures. Rock bursts are a serious hazard; in South Africa, they kill roughly 20 miners each year. Details Rock bursts result from brittle fracturing of rock, causing it to collapse rapidly with violent spalling 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 events, deriving from the strain energy produced by its geological aspects. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rockburst Damage
A rock burst is a spontaneous, violent failure of rock that can occur in high-stress mines. Although mines may experience many mining-related seismic events, only the tremors associated with damage to accessible mine workings are classified as rock bursts. The opening of mine workings relieves neighboring rocks of tremendous pressure, which can literally cause the rock to explode, or trigger abrupt movement on nearby geological structures. Rock bursts are a serious hazard; in South Africa, they kill roughly 20 miners each year. Details Rock bursts result from brittle fracturing of rock, causing it to collapse rapidly with violent spalling 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 events, deriving from the strain energy produced by its geological aspects. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geologic Fault
In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectonic forces, with the largest forming the boundaries between the plates, such as the megathrust faults of subduction zones or transform faults. Energy release associated with rapid movement on active faults is the cause of most earthquakes. Faults may also displace slowly, by aseismic creep. A ''fault plane'' is the plane that represents the fracture surface of a fault. A ''fault trace'' or ''fault line'' is a place where the fault can be seen or mapped on the surface. A fault trace is also the line commonly plotted on geologic maps to represent a fault. A ''fault zone'' is a cluster of parallel faults. However, the term is also used for the zone of crushed rock along a single fault. Prolonged motion along closely spaced faults can blur the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Outburst (mining)
An outburst is the sudden and violent ejection of coal, gas, and rock from a coal face and surrounding strata in an underground coal mine. When outbursts occur, they can be very serious events, possibly even resulting in fatalities. Effects of outbursts Outbursts may range in severity from being barely noticeable, to causing the destruction of an entire mining panel, and throwing pieces of machinery weighing tens of tonnes several metres. An outburst at Tahmoor Colliery, in New South Wales, Australia, in June 1985 involved the ejection of 350 tonnes of coal and rock and over 3000 cubic metres of gas, resulting in one fatality. Another outburst at the nearby South Bulli Colliery in 1991, resulted in three fatalities, and yet another outburst at Westcliff Colliery in January 1994 involved 300 tonnes of coal and rock and resulted in one fatality. Predisposing factors Several factors predispose certain coal seams to being outburst-prone. These include: * Coal seam gas content ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fault (geology)
In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectonic forces, with the largest forming the boundaries between the plates, such as the megathrust faults of subduction zones or transform faults. Energy release associated with rapid movement on active faults is the cause of most earthquakes. Faults may also displace slowly, by aseismic creep. A ''fault plane'' is the plane that represents the fracture surface of a fault. A ''fault trace'' or ''fault line'' is a place where the fault can be seen or mapped on the surface. A fault trace is also the line commonly plotted on geologic maps to represent a fault. A ''fault zone'' is a cluster of parallel faults. However, the term is also used for the zone of crushed rock along a single fault. Prolonged motion along closely spaced faults can blur the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vein (geology)
In geology, a vein is a distinct sheetlike body of crystallized minerals within a rock. Veins form when mineral constituents carried by an aqueous solution within the rock mass are deposited through precipitation. The hydraulic flow involved is usually due to hydrothermal circulation. Veins are classically thought of as being the ones in the body not the rock veins and arteries planar fractures in rocks, with the crystal growth occurring normal to the walls of the cavity, and the crystal protruding into open space. This certainly is the method for the formation of some veins. However, it is rare in geology for significant open space to remain open in large volumes of rock, especially several kilometers below the surface. Thus, there are two main mechanisms considered likely for the formation of veins: ''open-space filling'' and ''crack-seal growth''. Open space filling Open space filling is the hallmark of epithermal vein systems, such as a stockwork, in greisens or in cert ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drilling And Blasting
Drilling and blasting is the controlled use of explosives and other methods, such as gas pressure blasting pyrotechnics, to break rock for excavation. It is practiced most often in mining, quarrying and civil engineering such as dam, tunnel or road construction. The result of rock blasting is often known as a rock cut. Drilling and blasting currently utilizes many different varieties of explosives with different compositions and performance properties. Higher velocity explosives are used for relatively hard rock in order to shatter and break the rock, while low velocity explosives are used in soft rocks to generate more gas pressure and a greater heaving effect. For instance, an early 20th-century blasting manual compared the effects of black powder to that of a wedge, and dynamite to that of a hammer. The most commonly used explosives in mining today are ANFO based blends due to lower cost than dynamite. Before the advent of tunnel boring machines (TBMs), drilling and blas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Underground Mining (hard Rock)
Underground hard-rock mining refers to various underground mining techniques used to excavate "hard" minerals, usually those containing metals, such as ore containing gold, silver, iron, copper, zinc, nickel, tin, and lead. It also involves the same techniques used to excavate ores of gems, such as diamonds and rubies. Soft-rock mining refers to the excavation of softer minerals, such as salt, coal, and oil sands. Mine access Underground access Accessing underground ore can be achieved via a decline (ramp), inclined vertical shaft or adit. *Declines can be a spiral tunnel which circles either the flank of the deposit or circles around the deposit. The decline begins with a box cut, which is the portal to the surface. Depending on the amount of overburden and quality of bedrock, a galvanized steel culvert may be required for safety purposes. They may also be started into the wall of an open cut mine. *Shafts are vertical excavations sunk adjacent to an ore body. Shafts are s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Joint (geology)
A rock in Abisko fractured along existing joints possibly by mechanical frost weathering A joint is a break (fracture) of natural origin in a layer or body of rock that lacks visible or measurable movement parallel to the surface (plane) of the fracture ("Mode 1" Fracture). Although joints can occur singly, they most frequently appear as joint sets and systems. A ''joint set'' is a family of parallel, evenly spaced joints that can be identified through mapping and analysis of their orientations, spacing, and physical properties. A ''joint system'' consists of two or more intersecting joint sets. The distinction between joints and faults hinges on the terms ''visible'' or ''measurable,'' a difference that depends on the scale of observation. Faults differ from joints in that they exhibit visible or measurable lateral movement between the opposite surfaces of the fracture ("Mode 2" and "Mode 3" Fractures). Thus a joint may be created by either strict movement of a rock la ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dike (geology)
A dike or dyke, in Geology, geological usage, is a sheet of rock that is formed in a Fracture (geology), fracture of a pre-existing rock body. Dikes can be either Intrusive rock, magmatic or Sedimentary rock, sedimentary in origin. Magmatic dikes form when magma flows into a crack then solidifies as a sheet intrusion, either cutting across layers of rock or through a contiguous mass of rock. Clastic dikes are formed when sediment fills a pre-existing crack.Essentials of Geology, 3rd Ed, Stephen Marshak Magmatic dikes A magmatic dike is a sheet of igneous rock that cuts across older rock beds. It is formed when magma fills a fracture in the older beds and then cools and solidifies. The dike rock is usually more resistant to weathering than the surrounding rock, so that erosion exposes the dike as a natural wall or ridge. It is from these natural walls that dikes get their name. Dikes preserve a record of the fissures through which most mafic magma (fluid magma low in silica) reac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Induced Seismicity
Induced seismicity is typically minor earthquakes and tremors that are caused by human activity that alters the stresses and strains on Earth's crust. Most induced seismicity is of a low magnitude. A few sites regularly have larger quakes, such as The Geysers geothermal plant in California which averaged two M4 events and 15 M3 events every year from 2004 to 2009. The Human-Induced Earthquake Database (''HiQuake'') documents all reported cases of induced seismicity proposed on scientific grounds and is the most complete compilation of its kind. Results of ongoing multi-year research on induced earthquakes by the United States Geological Survey (USGS) published in 2015 suggested that most of the significant earthquakes in Oklahoma, such as the 1952 magnitude 5.7 El Reno earthquake may have been induced by deep injection of waste water by the oil industry. A huge number of seismic events in fracking states like Oklahoma caused by increasing the volume of injection. "Earthquake rate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rock (geology)
In geology, rock (or stone) is any naturally occurring solid mass or aggregate of minerals or mineraloid matter. It is categorized by the minerals included, its chemical composition, and the way in which it is formed. Rocks form the Earth's outer solid layer, the crust, and most of its interior, except for the liquid outer core and pockets of magma in the asthenosphere. The study of rocks involves multiple subdisciplines of geology, including petrology and mineralogy. It may be limited to rocks found on Earth, or it may include planetary geology that studies the rocks of other celestial objects. Rocks are usually grouped into three main groups: igneous rocks, sedimentary rocks and metamorphic rocks. Igneous rocks are formed when magma cools in the Earth's crust, or lava cools on the ground surface or the seabed. Sedimentary rocks are formed by diagenesis and lithification of sediments, which in turn are formed by the weathering, transport, and deposition of existing ro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Earthquake
An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in intensity, from those that are so weak that they cannot be felt, to those violent enough to propel objects and people into the air, damage critical infrastructure, and wreak destruction across entire cities. The seismic activity of an area is the frequency, type, and size of earthquakes experienced over a particular time period. The seismicity at a particular location in the Earth is the average rate of seismic energy release per unit volume. The word ''tremor'' is also used for Episodic tremor and slip, non-earthquake seismic rumbling. At the Earth's surface, earthquakes manifest themselves by shaking and displacing or disrupting the ground. When the epicenter of a large earthquake is located offshore, the seabed may be displaced sufficiently to cause ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
