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Sand Box (civil Engineering)
A sandbox or sand jack is a device used for removing the centering of an arch. Each prop A prop, formally known as a (theatrical) property, is an object actors use on stage or screen during a performance or screen production. In practical terms, a prop is considered to be anything movable or portable on a stage or a set, distinct ... is mounted on a sand box. After the plug is removed, the sand pours from the box, causing the centering to move downwards, diminishing the pressure from the arch, and enabling to ultimately remove it.Ashok Kumar Jain, B.C. Punmia, ''Building Construction'', Firewall Media, 2005, p. 435. References Arches and vaults Sand Tools {{civil-engineering-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Centring
Centring, centre, centering"Centering 2, Centring 2" def. 1. Whitney, William Dwight, and Benjamin E. Smith. ''The Century dictionary and cyclopedia''. vol. 2. New York: Century Co., 1901. p. 885., or center is a type of falsework: the temporary structure upon which the stones of an arch or vault are laid during construction. Until the keystone is inserted an arch has no strength and needs the centring to keep the voussoirs in their correct relative positions. A simple centring without a truss is called a common centring. A cross piece connecting centring frames is called a lag or bolst.Ching, Frank (1995). ''A visual dictionary of architecture''. New York: Van Nostrand Reinhold. p. 3. . Centring is normally made of wood timbers, a relatively straightforward structure in a simple arch or vault; but with more complex shapes involving double curvature, such as a dome or the bottle-shaped flue in a Norman-period kitchen, clay or sand bound by a weak lime mortar would be used. S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pit Prop
A pit prop or mine prop (British and American usage, respectively) is a length of lumber used to prop up the roofs of tunnels in coal mines. Canada traditionally supplied pit props to the British market. As coal mining declined in importance and metal supports were used, the term became infrequently used. Though it was merely a log cut to a particular length, it was classified as a finished product and so got around the extra Canadian tariffs on the export of raw lumber. Because of the large quantities exported, it is probable many ended up in British pulp mills. Most pit props were made from the wood of spruce A spruce is a tree of the genus ''Picea'' ( ), a genus of about 40 species of coniferous evergreen trees in the family Pinaceae, found in the northern temperate and boreal ecosystem, boreal (taiga) regions of the Northern hemisphere. ''Picea'' ... trees. References Coal mining {{mining-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arches And Vaults
An arch is a curved vertical structure span (engineering), spanning an open space underneath it. Arches may support the load above them, or they may perform a purely decorative role. As a decorative element, the arch dates back to the 4th millennium BC, but structural load-bearing arches became popular only after their adoption by the Ancient Romans in the 4th century Anno Domini, BC. Arch-like structures can be horizontal, like an arch dam that withstands the horizontal hydrostatic pressure load. Arches are usually used as supports for many types of Vault (architecture), vaults, with the barrel vault in particular being a continuous arch. Extensive use of arches and vaults characterizes an arcuated construction, as opposed to the trabeated system, where, like in the architectures of ancient Greece, China, and Japan (as well as the modern steel-framed technique), Post and lintel, posts and beams dominate. Arches had several advantages over the lintel, especially in the masonr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sand
Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is usually defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural class of soil or soil type; i.e., a soil containing more than 85 percent sand-sized particles by mass. The composition of sand varies, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non-tropical coastal settings is silica (silicon dioxide, or SiO2), usually in the form of quartz. Calcium carbonate is the second most common type of sand. One such example of this is aragonite, which has been created over the past 500million years by various forms of life, such as coral and shellfish. It is the primary form of sand apparent in areas where reefs have dominated the ecosystem for millions of years, as in the Caribbean. Somewhat more rarely, sand may be composed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
