man-made structures formed in the earth’s crust as a result of mining work. A distinction is made between exploratory excavations (to search and prospect for minerals) and operational excavations (for working the deposit). Mining excavations are open (located on the earth’s surface) and underground (within the earth).
A deposit that is covered by shallow detritus may be excavated by means of open mining excavations (pits or trenches). Underground mining excavations are carried out to work deep-lying deposits; by their position in space they may be vertical, horizontal, or diagonal. They may be in direct communication with the earth’s surface, or they may not have a direct exit to the surface. Mining excavations that have significant lateral dimensions in comparison with their length are called chambers, and excavations formed as a result of extracting minerals are called cleared excavations. The surface that borders the mining excavation and shifts as a result of mining work is called the face. The surface of rock that borders the excavation above is called the roof, whereas below it is the ground, or floor, of the excavation. The shape of the cross section of the excavation depends primarily on the type of supports, whose nature in turn is determined by the stability of the rocks and the period of service of the excavation. The dimensions of the cross section of the mining excavation are determined by production requirements, depending on the purpose of the excavation (transporting loads, ventilation, water outflow, and so on).
Vertical underground mining excavations include bore pits, mine shafts, wells, and winzes. Horizontal underground excavations include tunnels, drifts, breakthroughs, crosscuts, and cross drifts. Most horizontal excavations are made with a slight tilt (0.004–0.005) in the direction of the movement of loads in order to make transportation easier and ensure that water runs to the shaft header. Diagonal underground mining excavations include bore pits, mine shafts, inclines, slopes, grades, passages, rising excavations, furnaces, and connectors. Diagonal excavations of the first two types have the same purpose and the same general features as vertical mining excavations of the same name. Underground mining excavations also include boreholes—the excavation of a round section made by drilling and having a diameter that is insignificant in comparison with its length.
REFERENCESheviakov, L. D. Razrabotka mestorozhdenii poleznykh iskopaemykh,4th ed. Moscow, 1963.
V. G. AFONIN