DE1175162B - Method for producing a compressed air caisson - Google Patents

Description

Method of Making a Compressed Air Cesspool The invention relates to a method for producing a compressed air cesspool from concrete or Reinforced concrete, which - to lower a building ground below a body of water. is. Compressed air caissons are foundation bodies, which have an open bottom. Working chamber are provided and by excavating the soil under the protection of the working chamber be lowered into the subsoil, - whereby the groundwater by compressed air from the Working chamber is kept out. If the building site is under a body of water, it was previously common for compressed air caissons made of reinforced concrete, caissons to be produced in the dry on land or on scaffolding, and then to be launched from a slipway, to be brought into the water by floods from a dock, to float them in or to have them deployed by the crane, or to unscrew them from the scaffolding, until they reach solid ground. Also artificial islands with natural embankments or with sheet pile enclosures on which the compressed air caissons are made and lowered belong to the state of the art in this context.

All of these procedures have some fundamental shortcomings in common, which are most clearly expressed in the factors of cost, time and risk.

Unproductive costs arise for the preparation of the manufacturing stations, renting them and restoring them to their original state, as well as through transport to the installation site and lowering to the building site.

These preparations, the hardening of the Components up to the transportability of the compressed air caisson, the transport, the Swimming in, measuring the heavy and difficult-to-hold box, especially when it comes to open construction sites that are exposed to wind and weather.

There is already a high risk during manufacture, provided that this is the case does not happen on natural soil, due to the possible subsidence of the soil or the scaffolding, which expose the fresh concrete to unbearable stresses; further is the transport of such boxes - which are not from a shipbuilding point of view can be built - always a dangerous matter over open water high insurance premium. Another loss of time can be worse when it occurs Weather caused by delay in transport, although perhaps at the installation location there is definitely a job opportunity.

It is also already known, the walls of a fixed, no lowerable compressed air working chamber to be concreted under water.

The difficulties in making compressed air caissons in hydraulic engineering have become so much a matter of course that they are accepted without contradiction. The invention, however, shows a way that avoids a large part of these difficulties, by circumventing the operations that give rise to these difficulties will. The procedure for doing this is as follows: The compressed air caisson is not in the Produced dry, but under water at the place of later subsidence in the Subsurface by, according to the invention, initially a with a per se known, Non-watertight formwork clad framework made and at the installation site is lowered to the bottom of the water, whereupon the concrete of the caisson in a known way as underwater concrete leaving at least one recess for a shaft is introduced.

The formwork can. made of sheet metal, wood, concrete slabs or whatever other suitable material and, as far as possible,. taken again will; the concrete will. , be it directly as funnel concrete in the contractor process, be it through ',: nbrinapn of the aggregate material and concreting in the co] cret or Prepakt or any other safe form of concrete pouring.

Concreting underwater is the case with today's cement qualities and the available tried and tested procedures are hardly a risk. A mixture of the concrete with sea water is to be rendered harmless on the one hand by choosing the cement, on the other hand, to connect by the colloidal mortar. The result of setting a denser concrete is likely to be under water than is possible over terrain.

The advantages of this process are manifold: The framework with the inner and outer formwork is relatively light, so it can be done without huge Transport costs are brought to the site and with the help of guide posts or scaffolding or can also be discontinued without such. It is enough for the alignment two or few measuring rods protruding over water. This increases the amount of work and time required the previously required work space is significantly reduced. Launching and towing are completely eliminated, as are the associated risks. The weaning, yourself one Repeated adjustment is easy work compared to fiddling with finished compressed air caissons.

All stresses from the launch are omitted for the box the high stresses caused by tipping or floating up during transport tensile forces and strains can occur in several directions, and lowering.

The box also no longer needs to have swimming stability in different Stages of its path to be examined.

All these work process savings mean time savings, the is of the utmost importance especially for hydraulic structures because it avoids the risk helps. The concreting can be done on a fair weather day and will be done at good preparation can usually be done in one day.

The formwork does not need to be made watertight because it is surrounded on all sides by water and makes it difficult for the concrete to flow out will.

The structure of the caisson part above the working chamber can be the same Way, it can also be continued in any other way through top caissons, by means of pillar jackets made of steel or reinforced concrete prefabricated parts, by means of masonry Prefabricated blocks or massive structures produced by underwater filling will. In any case, the accessibility of the working chamber is through a cavity for the manhole. After the concrete has hardened sufficiently the working chamber is the caisson in the usual way with a shaft and sluice provided and lowered under compressed air.

The skeleton is expediently made of one in a manner known per se Steel framework or precast reinforced concrete parts. It is advantageously designed so that it is in the ready-concreted caisson for the stresses during the lowering process necessary reinforcement.

According to a further feature of the invention, the underwater concrete first introduced in an edge zone against a temporary inner formwork and in a second step after removing the inner formwork a lower-quality filler concrete can also be poured under water.

In the drawing ( Fig. 1 and 2) a caisson is shown after concreting has been completed. The process is that first a steel frame b is deposited entirely or partially together with a formwork c, the necessary reinforcement e and a formwork for the production of the shafts a on the river bed. After the framework has been aligned in its position, the concrete d is poured under water. When this has hardened sufficiently, the caisson can be lowered in the usual way.

Claims (4)

Claims: 1. A method for producing a compressed air caisson, which is to be lowered into a building ground under a body of water, made of concrete or Reinforced concrete at the installation site, characterized in that initially one with a known, non-waterproof formwork (c) clad framework (b) produced and is lowered to the bed of the water at the installation point, whereupon the concrete (d) the caisson in a known way as underwater concrete leaving at least a recess for a shaft (a) is introduced. 2. The method according to claim 1, characterized in that the framework (b) in a known manner from a Steel framework or precast reinforced concrete parts. 3. The method according to claim 2, characterized in that the framework (b) is designed so that it is finished concreted caisson the necessary for the stresses during the lowering process Reinforcement forms. 4. The method according to any one of claims 1 to 3, characterized in that the underwater concrete is first introduced in an edge zone against a temporary inner formwork and in a second operation after removing the inner formwork, a lower-quality filler concrete is also introduced under water. Publications considered: Swiss Patent No. 85691; U.S. Patent No. 2050727; Schoklitsch, "Der Grundbau", Springer-Verlag, Vienna, 1952, p. 405; "Die Bautechnik", Issue 10, 1930, pp. 142, 143.