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Mine
an artificial formation in the Earth's crust created by mining. Mines can be divided by type into exploratory (searching for and mapping minerals) and operational (the development of a deposit). Mines may be opencast (on the surface) or underground (sub-surface). A deposit covered by only a thin layer of overburden may be developed using opencast mining (trenches, channels).
Underground excavations are used to develop deep-lying deposits; depending on their layout they may be vertical, horizontal or inclined. Such mines may lead off directly from the surface or may have an indirect entrance. Excavations that have a significant diameter relative to their length are known as chambers, while stopes or rooms are the formations that result from the extraction of minerals. The surface that delimits the end of an excavation and moves as a result of mining activity is known as the face. The rock surface above an excavation is known as the roof, while that below it is known as the bed or footwall.
The shape of an excavation in cross-section depends mainly on the type of support used, which is in turn determined by the hardness of the rock and the working lifespan of the mine. The size of an excavation in cross-section depends on the technological demands imposed by the section’s purpose (transportation, ventilation, drainage, etc.)
Vertical underground excavations include prospecting holes, mine shafts, well holes and dummy shafts. Horizontal underground excavations include galleries, longitudinals (drives), breakthroughs, offsets and crosscuts. Most horizontal excavations have a very slight incline (0.004-0.005) in the direction of load movement to make transport easier and to direct water toward the drainage system. Inclined underground excavations include prospecting holes, mine shafts, brake inclines, escarps, dipping drifts, passes, rises, rise entries and connections (the first two types serve the same purposes and have the same basic characteristics as the vertical workings of the same name). Other types of underground excavation include boreholes, which are round holes created by drilling that have a very small diameter relative to their length.
