Drilling-wedging extraction of stone
DRILLING-WEDGING EXTRACTION OF STONE (EN: wedge-drill output, stripping output; DE: Keillochbohren; FR: abattage avec bouchon en coin; ES: extraccion de piedra con cunas; RU: буроклиновая добыча) is the method for the separation of the blocks of the rock from the massif by the preliminary encircling drilling of the bench by the blastholes, and by the subsequent splitting of the blocks from the massif by the wedges.
The drilling-wedging extraction is known since the most ancient times (for example, within the ancient Egypt, they obtained by this method the blocks for the construction of the pyramids). The drilling-wedging extraction is used during the development of the deposits with the facing stone of the strong rocks, less often of the rocks with the medium strength; the drilling-wedging extraction is used mainly in the combination with other mechanized methods for the separation of the blocks from the massif: stone-cutting, thermal, and so on.
In case of the drilling-wedging extraction, there are used in the maximal manner the natural cracks within the massif. On the bench, at the sole of which there exists usually the natural fracture, they penetrate the leading trench, which is creating the free face, by the method of the continuous encircling drilling, or by the drilling-blasting method. Later, they form the back face of the monolith, which is intended for the separation (in case of the absence of the natural fracture), by the method of the cutting of the slit-cutter by the thermal cutting tool, by the stone-cutting drilling machine, or by the drilling tool (the continuous encircling drilling). Along the remaining face, they separate the monolith from the massif, for which action, along the line of the intended split, they drill by the hammer drills the row of the blastholes, into which they insert the wedges. With the help of the wedges, they separate the monolith, which has been splitted from the massif, into the blocks. The wedges, which are used during the drilling-wedging extraction, may be simple or combined. The simple wedge (which is manufactured of steel) has the triangular or circular cross section, with the length of 100-200 millimetres, with the angle of the tapering of 25-30 degrees. The combined wedge includes the wedge proper with the angle of the tapering of 10-12.5 degrees, and the two cheeks, which are representing by themselves the half-cylinders with the conical surface within them. There are distributed the hydraulic wedges.
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