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(Russian, garnisazh; from French garnissage), a hard protective layer formed during a melting process on the inner (working) surface of some metallurgical units subjected to intensive cooling. In furnaces with cooled lining, the lining is principally obtained as a result of physical and chemical interacting of the charge, gases, and the material of the cooled walls; in furnaces without lining it is obtained as a result of intensive water cooling of the molten or softened charge products in metallic cooling units (usually copper or steel). In the last case, thin crusts of solidified products are formed, with the thickness depending on melting conditions, especially on the furnace’s cooling speed.
(or casing), a member that reinforces an underground structure and imparts to it the shape required for normal use.
In contrast to temporary mine support, lining is designed for permanent use. The shape and size of lining are determined by the dimensions, depth of bedding, and purpose of the underground structure (tunnels, underground hydroelectric power plants, garages, warehouses, and wine cellars), and also by the nature of the loads acting on the structure (rock pressure, hydrostatic pressure, and traveling loads). Lining may be made from cast concrete and reinforced concrete, prefabricated concrete, or metal (cast iron or, less frequently, steel). Tunnel lining is characterized by great diversity.
Cast concrete and reinforced-concrete lining is used mainly in tunnels of highly complex design and large cross section, usually driven by the heading method. The tunnels may be rectangular (the most common type), as well as oval or parabolic. As of 1974, research and development work on the introduction of a new type of cast-pressed lining was under way. Such lining is particularly suitable for the construction of hydraulic-engineering tunnels and open-line subway tunnels that are driven by the shield method and is distinguished by high strength and water-impermeability and by the smoothness of the inside surface.
Prefabricated lining may be curved or rectilinear. The first type is used mainly for tunnels driven by the shield or erector method (mainly subway tunnels). Prefabricated curved lining may be made from cast iron or reinforced concrete. Cast-iron lining (cast-iron tubes) is used in water-saturated rock with high hydrostatic pressure; reinforced-concrete lining may have a solid cross section, or it may be ribbed. It is used in comparatively dry rock. Imperviousness to water is achieved by waterproofing the joints (for example, with expanding cement) or by grouting the space around the lining with a mixture of sand and cement (or bentonite). If the tunnel is being driven in a waterlogged area, prefabricated reinforced-concrete lining can be made water-impermeable by means of an internal waterproof cover in the form of a jacket or by providing an external or internal shield during manufacture of lining modules. In weak clay and sand soils (particularly in the construction of shallow tunnels), prefabricated reinforced-concrete lining that is compressed by the rock can be used effectively; thus, the rock mass and the lining work together to prevent settling of the upper soil layers. Prefabricated reinforced-concrete lining with a rectilinear contour has been widely used for subway tunnels constructed by the trench method. This type of lining can be made water-impermeable by applying a waterproofing coating to the outside or by gluing on a waterproofing material in roll form (waterproof glass fabric, polyethylene, and so on). The waterproof covering is applied during production of lining modules.
REFERENCESChasovitin, P. A. Tonnel’nye obdelki iz sbornogo zhelezobetona. Moscow, 1959.
Tonneli i metropoliteny. Edited by V. P. Volkov. Moscow, 1970.
IA. G. GEL’MAN
(in Russian, futerovka), a protective covering on the inner surface of a heat-producing unit and its components—for example, a furnace, a firebox, a ladle, a flue, or piping—and of chemical equipment, such as an etching bath. A lining may be made of bricks, slabs, blocks, concrete, a rammed material, or shotcrete. Depending on the purpose of the lining and on the type of material used, a lining may be refractory, acidproof, or heat-insulating.
In Russian, the term futerovka is sometimes also applied to a facing—that is, to a protective covering on the outer surface of a component—if the component’s outer surface is subjected to, for example, heat fluxes or corrosive agents.