In general construction, a bulwark (also outdated: Bohlwerk ) refers to the supporting wall of a body of earth consisting of a row of driven piles . The piles are top by a beam connected behind the strong piles are plank inserted. Such a timber frame serves as a replacement for lining and free walls , especially in swampy and stone-poor areas . In the fortress construction, bulwark originally meant a protective fence or protective wall built from wooden planks rammed into the earth.
In general construction
The bulwark piles must be driven so deep into the ground and made so strong that they cannot be pushed over or broken off by the backfilled earth. Their mutual distance depends on the strength of the available planks, of which the lowest ones experience the strongest earth pressure and nevertheless must not be bent.
If the subsurface into which the pile piles are driven is not strong enough to give the bulwark the necessary stability, it must be braced or anchored. If the space in front of the plank wall does not have to remain free, struts are used, whereby special earth piles are rammed in in front of the plank wall and connected to the bulwark piles with cross tongs before the struts braced against a continuous horizontal connecting bar of the bulwark piles are used.
If, on the other hand, the space in front of the plank wall has to remain free, a construction is used in which the above-mentioned earth piles are rammed in behind the plank wall and connected to the bulwark piles by similar cross tongs. The struts stressed here on train are bolted above by screws and short cross-tongs both with the above-mentioned horizontal ledgers and with the bulwark piles.
In both cases, the earth piles must be driven in as firmly as possible, since the earth pressure tends to depress them in the first case and to pull them out in the second. A second anchoring bulwarks by so-called anchor piles has particular application bulwarks with applied bulwark piles, in which on a number of strong under low water driven-base piles which a decay not subject placed the bulwark wall and at the connection point by a connecting bar and by iron Brackets, which are connected to each other again by cotter pins , is secured against displacement.
A rotation and overturning is prevented by the anchor piles connected by means of a horizontal bolt, which are firmly connected to the bulwark piles, which are also connected by a horizontal bolt, by means of cross tongs. With this arrangement of the bulwark, the fodder planks sit on the lower horizontal ledger and are cut out as far as the cross-tongs require in the event of decay and necessary repair of the same.
In fortress construction
The word bulwark is derived - just like the word palisade - from the oldest man-made fortifications, namely a series of stakes, planks or tree trunks rammed or dug into the ground. (Middle High German: bolen , Bohlen) Bollwerk was originally the name for a protective fence made of planks (piles) and ultimately derived from this for the entire fortification. Only in modern times (from the 16th century) was the term increasingly restricted in the technical language of fortress construction to a system flanking the main wall, while in common parlance a particularly strong fortress is understood.
In the technical terminology of modern fortress construction, every structure protruding from the wall line is called a bulwark. The purpose of such a system was to be able to paint the side of the space immediately in front of the wall , which the defenders cannot see from the parapet . Bulwarks are therefore the flanking part of a fortress wall and thus have the same function in a modern fortress as the towers of an ancient or medieval city wall. In the technical terminology of the (German) fortress construction, the term Bollwerk was not tied to a specific form of construction, but could be used as a synonym for bastion , bastion or roundell (roundel) or any other flanking structure.
In hydraulic engineering
The river navigation took in the 19th century ever since existed in the area is very poor transport facilities. Since the landlords had to bring their products to the processing and recycling facilities, especially in Mecklenburg , Pomerania and Brandenburg , it was necessary to create suitable transport routes. These areas were largely provided with rivers, which were cheap transport routes. For this purpose, loading points also had to be built on the rivers. For this purpose, quays were created in the cities, but suitable mooring options also had to be built in the area. These were the so-called bulwarks. These bulwarks consisted of rows of stakes that were driven into the river floor, where there was already sufficient water depth for the river barges, which were still quite shallow. The piles were provided with horizontal cross braces to which vertical wooden planks with rabbets were attached as sheet piling. The woodwork was usually made of durable oak. This construction was backfilled with earth towards the bank. In a cheaper way, areas with wooden planks were built as a platform at these loading points. These loading points were connected to the mainland via dams, on which the goods to be loaded were approached by horse and carts or later with light rail trucks. Many goods had also built brickworks for their own use, which then also produced commercial goods, depending on the clay deposits. These were also connected to the light rail network and via this to the bulwarks. When railway lines were built from the 1860s and small railways in the 1890s, river navigation declined again and the bulwarks were superfluous in the areas touched by the railway and fell into disrepair. They were only maintained and even expanded where there were no rail connections or where reloading points from the railways to river navigation were necessary. These remains of the bulwarks can still be seen today on the rivers, such as the Peene in Western Pomerania . Sometimes they are used as mooring points for leisure boats and anglers.
In other languages
The word bulwark found its way into other languages in a slightly different form. The Middle Dutch form (bulwerke) of the word was adopted in French, the boulevard . In the Catalan language, bulwark evolved from medieval French boulouart to baluard. In English, the spelling was bulwark .
It can be found, for example, in the name of the Museum of Modern and Contemporary Art in Palma de Mallorca: Es Baluard .
- Karl Heinz Clasen: Bulwark. In: Reallexikon zur Deutschen Kunstgeschichte , Vol. 2, 1942, Sp. 1030-1033
References and comments
- ↑ In contrast to the construction section, the word is not understood here as sawn timber, but in its original meaning, namely post or tree trunk.
- ↑ Origin dictionary of the Duden, sv Bohle, sv Bollwerk
- ^ Lexer, Middle High German Pocket Dictionary, 1932, sv bole
- ^ Zastrow: History of the constant fortification , 1839, 1ff
- ↑ Almost parallel to this, the word "palisade" gradually takes on the original meaning of the word "bulwark"
- ^ Riistow, Military dictionary, sv Bastion
- ^ Bernhard von Poten : Concise dictionary of the entire military sciences. 1878, sv Bastion; Riistow, military dictionary, sv Bastion
- ↑ the English bulwark (bulwark), on the other hand, probably comes straight from the Saxon language (see also Webster's New Collegiate Dictionary, sv bulwark)