Decauville shore fortification

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The Cuirasse Decauville was first exhibited at the Champ de Mars from March 18th to 24th, 1908 .
The perforated bricks were threaded onto wire ropes with a keyboard
Decauville - briquette press

The Decauville bank fortification ( French La Cuirasse Decauville ) was a bank and embankment protection system invented by Paul Decauville , in which pressed, prismatic concrete bricks, which had two through holes in the middle , were mounted on galvanized wires with a device called a keyboard .

system

The patented shoreline and bank reinforcement consisted of an 85mm thick flexible pavement of concrete bricks held together with galvanized steel wires and placed on a prepared embankment with variable gradients. The bricks were produced on site using a small steel-made briquette press that weighed 475 kilograms, could be transported on four wheels and exerted a pressure of 20 tons on the two bricks of each brick.

Each brick was 260mm long at the front and 210mm at the back, 135mm wide and 85mm thick and weighed around 5kg. It was provided with two ø 18 mm holes through which ø 3 mm thick galvanized steel wires were passed. The grooves made at the top and bottom made it possible to insert a seal for the protection of fine sand during laying.

The bricks were made with a mixture of 300 kg of Portland cement per cubic meter and granular, siliceous and well-washed sand, which was kneaded well with as little water as possible. A crew of four workers, two on the press and two on the shuffle, could make about 700-800 bricks in a 10-hour day. The bricks were removed from the press with tongs that looked like waffle irons and laid on the floor in rows that could be three tiers high. The day after making them, they were placed in a water bath to complete the hydration, which made them harder. A fifth worker was engaged in this work, which is quite lengthy. The bricks could only be laid three weeks after they were made. Therefore, each building site had to have sufficiently large covers to allow the bricks to dry before use.

The whole system was based on a galvanized steel cable, similar to the three- or four-core cables also used to brace the pylons of power lines, to which were attached the wires, inclined according to the slope to be protected, and the perforated bricks Recordings. The attachment was done very quickly using special tools and in such a way that the wires can run along the cable. When the ground was prepared to the desired slope, the ground cable was secured to the foot either with wooden pegs, iron pins or on a foundation of branches, then the 3mm thick steel wires were attached to this ground cable.

Worldwide applications

First use cases

River straightening in Longwy-sur-le-Doubs in France
First application examples

One of the first uses was in March 1911 for river straightening along the Rue de la Lisse in Longwy-sur-le-Doubs in France. By using short bricks, the bank reinforcement could be built in a sharp curve. The workers got used to this work very quickly. This use of the Decauville bank protection was of great interest for the water supply of the waterworks.

In Japan , a Decauville shore fortification was laid in Kinugawa Onsen , (en) a neighborhood of Nikkō in Tochigi Prefecture , on the banks of the raging Kinu River (鬼怒川, Kinu-gawa) (en) . Denys Larrieu, the concessionaire for Japan, deployed a 286 meter long and 3 meter wide flexible bank protection at the base of a 3:2 slope that automatically lowered as the river gnawed at the base of the protection.

In Switzerland , the Federal Building Inspectorate had two partial structures built using this system in 1911: one on the Zulg , a torrent near Steffisburg with a large amount of debris , and one on the Aare below the town of Thun . Around 1913 three more protective structures were constructed in the Broye Valley: one on the Fossé Neuf , a tributary of the Petite Glâne , one on the Broyé near Corcelles and the third on the shore of Lake Murten near Salavaux in Vallamand . At Lake Murten, whose water level fluctuates around 2.70 m, the lake's waves have caused major erosion. Since the ground was sandy, the cuirasse was laid on tar paper with a gradient of 2:1 . The shorter stones for the left connecting surface were made with telescopic wedges. The lower part of the quay walls of the port of Yverdon was protected by a Decauville embankment, which was 0.50 m above the high tide. Stairs have been installed in the upper part to facilitate accessibility between the docks and the ships.

In Egypt , the Decauville bricks were laid on the south bank of the Kazed Canal at Tanta , a city in the Nile Delta between Alexandria and Cairo . The Arab construction workers quickly became familiar with the production. After seeing the beautiful appearance of the Decauville bank fortifications on both banks of the Kazed Canal while crossing the town of Tanta, the English engineers of the Egyptian government, noting the reports prepared by Messrs. Hersent on the bank fortifications' strength, English engineers set the system over a length of 1200 m and a height of 2.72 m on the dike of El Max (en) near Alexandria.

For the 1911 Turin World Fair , a so-called Corazza Decauville was erected on both sides of the Po River under the footbridge of the United States Exhibition Pavilion and on the opposite bank in front of the Siam and England pavilions.

When World War I broke out, five Decauville presses were in use on the banks of the Tigris along the Baghdad railway , as well as others in Belgium, Russia, Serbia, Romania, Bulgaria and probably also in Japan, Chile and Algeria.

More use cases in France

Protection of the Seine embankment from Asnieres , at the Pont de Clichy

literature

Commons : Decauville Embankment  - Collection of images, videos and audio files
La Cuirasse Decauville on a postage stamp, 1907

itemizations

  1. ↑ Clavier serre-tils pret a embarqueur sur le travallieur; à Pointe de Grave iy avait une batterie de 10 claviers de ce type (A keyboard with tool clamps that could be carried on a barge; at Pointe de Grave there was a battery of 10 such keyboards).
  2. ^ a b L. Deluz: La Cuirasse Decauville . Bulletin technique de la Suisse romand, No. 7, April 10, 1913.
  3. ↑ a b La France au travail: Revue mensuelle illustrée pour l'organization économique de la nation. December 1916, pp. 10, 11 and 13.
  4. ↑ W. Martin, A. Chenaux and Ph. Kaempf: Avant-projet-detaillé du Canal d'entreroches. p. 197.
  5. ↑ Cuirasse Decauville - Le plus simple, le plus solide et le plus économique de tous les revêtements.
  6. ↑ Travaux de Protection des Dunes, Berges, Digues, Canaux et Talus de Chemins de Fer. Universal Exposition 1911 Turin. p. 72.