EP0423105B1 - Prefabricated structural element to be used as a cellar - Google Patents

Abstract

The prefabricated element consists of a reinforced concrete shell (2) of any required shape and dimensions, comprising a base slab (3) and vertical side walls (4). A top closure slab (5) including an access opening (6) for a stairway may be formed integrally with the walls. The base slab extends beyond the peripheral line of the side walls by at least 20cm. The side walls are tapered towards their bottom edges to allow removal of the whole shell casting from a mould in which it is formed. The base slab forms an integral foundation to support the entire weight of the construction.

Description

The present invention relates to a prefabricated reinforced concrete construction element, intended to serve as a cellar, this element consisting of a reinforced concrete shell of any shape and size, comprising a floor slab and vertical walls possibly provided a cover slab provided with a staircase access hatch.

The prefabricated waterproof construction element made of reinforced concrete is mainly intended to be used as a cellar for traditional small and medium-sized residential and service buildings.

Incidentally, the prefabricated building element can have various functions, in particular that of a foundation-bearing element buried in the ground or placed on the ground surface: cellar, well, tank, machine frame and shelter.

Document FR-A-2,589,899 discloses a cellar of the type intended to be buried in the ground. They are a prefabricated building element made of reinforced concrete and consisting of at least three vertical walls arranged in a closed polygon, a floor slab secured to the vertical walls and a roof fixed on the upper edge of the vertical walls.

The installation of this known prefabricated building element generally does not require any drawdown of the aquifer except in the event of difficulty caused by it.

The excavation of a hole requires no special attention because there is no particular danger when making the hole on the very short execution time.

As soon as the prefabricated building element is deposited in the freshly dug hole, the edges of the hole around the prefabricated building element are filled with gravel or stabilized sand. The prefabricated building element may be filled with water to prevent it from floating.

The main drawbacks of known prefabricated building elements are as follows: the entire prefabricated element, except the normal backfill around the hole, does not allow any external load from the building to which said prefabricated building element belongs.

• Toutes les assises de fondation à côté et autour de l'élément de construction préfabriqué destiné à servir de cave doivent être réalisées jusqu'à la profondeur de la cave au moins;
• un sol et/ou des hourdis séparés peuvent être réalisés au-dessus de la dalle de recouvrement, qui transmettent l'ensemble des forces appliquées, provenant du bâtiment, aux éléments de fondation disposés à côté de l'élément de construction préfabriqué (ce qui est parfois difficile sinon irréalisable);

This means that:

• All foundation foundations next to and around the prefabricated building element intended to serve as a cellar must be made to the depth of the cellar at least;
• a floor and / or separate slabs can be made above the cover slab, which transmit all the applied forces, coming from the building, to the foundation elements placed next to the prefabricated building element (which is sometimes difficult if not impracticable);

The realization of these force recovery constructions above the prefabricated building element intended to serve as a cellar requires a determined construction height, which makes it necessary to place the prefabricated building element to a greater depth by driving deeper foundations for the recovery in overhang compared to the prefabricated building element of additional stress concentrations.

Document FR-A-1510032 describes a foundation for individual or collective houses built around prefabricated cellar elements which can be transported.

In all cases, the perimeter of the foundation is smaller than that of the house, so that only a cantilevered support or possibly masses of the house is ensured.

Likewise, the document GB-A-1205 497 describes a three-dimensional monolithic building structure in reinforced concrete and a method for producing it using a formwork comprising interior panels and exterior panels distant from each other, from so as to delimit walls or slabs of desired thickness integral with each other. It describes the use of an expandable concrete but it does not suggest any means or solution to overcome the considerable static pressure of the mortar to allow the pouring of the mortar over the entire height of the formwork, if the concrete is poured in one phase.

To increase the lift of the prefabricated cellar element, the present invention provides an element of prefabricated construction of the type described in the first paragraph of said specification, characterized in that the floor slab projects beyond the vertical walls.

The manufacture of such a prefabricated building element is made possible by the fact that the mold is placed in the inverted position, before introducing a reinforcing reinforcement there and pouring the concrete not yet set there.

According to a feature of the invention, the vertical walls of the prefabricated building element are flared downward in order to allow the assembly of the whole of the prefabricated building element.

In a particular embodiment, the prefabricated building element can accommodate building elements, such as columns and / or foundation beams, which can be sealed using anchoring means, in particular buttons anchor to the walls so as to form a monolithic whole with the cellar and the building.

All normal and traditional activities can be continued immediately after the placement of the prefabricated building element intended to serve as a cellar (placement of adjacent foundations, backfill etc ...) even without a protective plate being placed or any shoring work carried out.

The walls make it possible to take up rectilinear stresses, parallel or perpendicular with respect to the walls, constraints or point loads transmitted by columns without any particular precautions for distributing the loads in said walls.

The width of the walls resting on the ground makes it possible to glimpse all the possibilities of recovery, which can relate to the rest of the building.

Load-bearing walls can be erected directly on the walls. These particularities and details of the invention, as well as others will appear in the description of the attached drawings, which show schematically and without limitation, an embodiment of the invention.

• la figure 1 est une vue en coupe verticale d'un élément de construction préfabriqué destiné à servir de cave selon l'invention, à fonction portante ;
• la figure 2 est une vue en coupe horizontale de l'élément de construction préfabriqué illustré à la figure 1;
• les figures 3 à 10 illustrent schématiquement les diverses étapes de fabrication de l'élément de construction préfabriqué montré dans les figures 1 et 2;
• les figures 11 à 15, illustrent le placement de l'élément de construction préfabriqué dans le puits; et
• les figures 16 à 20, représentent schématiquement des images d'autres possibilités de réalisation de l'élément de construction préfabriqué destiné à servir de cave.

In these drawings:

• Figure 1 is a vertical sectional view of a prefabricated building element intended to serve as a cellar according to the invention, with load-bearing function;
• Figure 2 is a horizontal sectional view of the prefabricated building element illustrated in Figure 1;
• Figures 3 to 10 schematically illustrate the various stages of manufacture of the prefabricated building element shown in Figures 1 and 2;
• Figures 11 to 15 illustrate the placement of the prefabricated building element in the well; and
• Figures 16 to 20 schematically show images of other possibilities of realization of the prefabricated building element intended to serve as a cellar.

In these different figures, the same reference signs designate identical or analogous elements.

As illustrated in FIGS. 1 and 2, the prefabricated building element 1 according to the invention intended to serve as a cellar, comprises a concrete shell generally designated by the reference sign 1 comprising a floor slab 3 and walls vertical 4 at right angles.

The shell 2 is optionally provided with a covering plate 5 with access opening to a staircase 6.

To increase the bearing force of the prefabricated building element 1, the floor slab 3 projects from the vertical walls 4.

The prefabricated building element 1 is made of noble concrete, mechanically vibrated and reinforced with steel filaments (hardness after 28 days = 60 N / mm²). This reinforcement consists of steel filaments with turned ends cold drawn and protected against corrosion having a tensile force of at least 1100 N / mm². The minimum reinforcement content of steel filaments is 30 kg per cubic meter of concrete. It can be increased according to the needs determined by calculation.

If necessary and depending on the calculations, the floor slab can be reinforced with additional concrete bars or with a BE 500 welded mesh.

Additives to the concrete composition can be added to improve the workability or density of the concrete.

All the parts of the prefabricated building element in contact with the ground are covered with two layers, sprayed under pressure, of varnish formed from tar and bitumen.

For information, the normal composition of concrete, given per cubic meter, is as follows:
750 l of fine gravel 7/14;
500 l of coarse sand 0/5;
380 l of P40 cement;
30 kg of steel fibers.

This concrete is prepared according to a precise and permanently controlled composition, in particular with the same water content in a mixer in the factory itself.

During mixing, the necessary amount of corrosion-resistant steel fibers is added to the mixture to strengthen it.

A mold 7 of the prefabricated building element, made up of reinforced metal panels, forms a stable and non-deformable construction on which can be mounted vibrators 8 fixed to the mold 7. The mold cleaned and coated with a release oil is placed in the inverted position.

Pouring the concrete into the mold 7 deposited upside down is carried out by the following three steps:
- the fresh concrete is poured by means of a pyramidal hopper between the walls of the mold 7 arranged upside down, while the vibrators 8 fixed to the mold ensure perfect compaction of the concrete (fig. 3).

After concreting the walls 4, the distribution hopper is removed and removed, the reinforcing frame for the concrete slab 3 is optionally mounted and the concrete poured to form the concrete slab 3 (fig. 4).

After vibration, the upper face of the assembly is perfectly smoothed (fig. 5).

Above the mold 7 filled to the brim, a protective plate is securely fixed to the assembly using a circlip system (fig. 6).

The manufacturing process is continued, using a heavy tilting machine, developed by the inventor himself, mounted on wheels and brought above the mold. The assembly is lifted by means of gyration rings 12 driven by hydraulic motors and returned to the service position (fig. 7). The tilting machine then moves the mold to a warehouse where the mold is placed (fig. 8).

After unlocking the clipped bottom plate, the mold is lifted slowly so as to release the prefabricated building element which rests on the protective plate until after hardening.

In a possible variant with covering plate 5, said covering plate can be cast on site in said position above the prefabricated building element, by providing an access opening to a staircase 6 there (fig. 10) .

The prefabricated building element is transported using a heavy vehicle to the site.

The hole 13 is mechanically dug. Under normal circumstances, given the very short lead times, a prior lowering of the aquifer is not necessary. Using a sophisticated measuring device, it is checked that the bottom of the well is flat at the desired depth.

Using a sufficiently powerful crane 14, the prefabricated cellar is placed without impact in the bottom of the hole (fig. 11). The concrete is then immediately backfilled to the desired height using an improved or non-improved backfill material (fig. 12). Partial filling of the prefabricated building element intended to serve as a cellar with water is only necessary when the weight of the prefabricated building element and the bearing capacity of the soil resting on the projecting rim of the prefabricated building element are insufficient to prevent it from floating on the aquifer. If the aquifer is drawn down, the pre-filling of the prefabricated building element with water can be eliminated.

In the absence of sufficiently bearing soil at the level of the cellar floor, it can possibly be placed on stabilized soil or on foundations (fig. 13 and 14).

The prefabricated cellar is a building element that is an integral part of the building as a whole.

The vertical walls 4 are crushed conically, in order to make it possible to demould the entire cellar.

The floor slab 3 is preferably projecting 20 cm from the walls 4. It serves as a foundation slab for the self-weight of the cellar, annexes and loads applied to the cellar and coming from the building (fig. 15 ).

All the loads supported or applied on the prefabricated building element, including the self-weight, are transmitted without deformation of the floor slab 3, to the underlying bearing soil.

The prefabricated building element allows the forces coming from the upper floors 18, load-bearing walls 19, cantilevered walls 20 (fig. 16 to 18), point loads and the like to be transferred directly to the floor slab 3 of the cellar. along the walls.

As a result, additional foundations below the cellar are made superfluous (except on non-bearing soil).

Significant one-off loads and / or columns can be carried out without having to resort to constructions making it possible to distribute the loads.

Construction elements such as columns 21 and / or foundation beams 16 can be fixed to the walls using anchoring means, in particular anchoring bolts or chemical anchors 17, so as to be an integral part of the cellar and the building.

By its composition and its manufacture in a particular stage, the cellar produced is perfectly watertight, which makes it unnecessary to seal using seals. Any partitions can be fitted at any time in the cellar without requiring sealing.

Thanks to the integrated integral construction of the prefabricated element according to the invention, the possible fixing of various elements has no harmful influence on the maintenance of a perfect seal.

Due to the compaction of concrete in the mass, the fixing of shelves, pipes and the like, carried out directly in the walls 4 causes practically no infiltration of water at the anchor points.

The width of the walls makes it possible to install any type of load-bearing floor and one can even establish load-bearing walls there, wider than the walls of the prefabricated building element themselves (fig. 18).

The floor slab 3 which overflows from the walls, significantly reduces the danger of the cellar flotation under the possibly too strong pressure of the water, thanks to the additional weight of the earth fill mass around the prefabricated building element intended to serve as a cellar.

• Dans la majorité des cas, un rabattement de la nappe aquifère peut être évité sauf cas exceptionnel;
  Si un rabattement semble malgré tout indispensable, celui-ci peut être arrêté immédiatement après le placement de l'élément de construction préfabriqué et le remplissage partiel de celle-ci à l'aide d'eau.
• Le puits creusé autour de l'élément de construction préfabriqué, peut être immédiatement remblayé, ce qui exclut des glissements de terrain et des effondrement ultérieurs éventuels.

The completely prefabricated and finished construction element allows rapid placement, thanks to which:

• In most cases, a drawdown of the aquifer can be avoided except in exceptional cases;
  If a drawdown nevertheless seems essential, it can be stopped immediately after the placement of the prefabricated building element and the partial filling of it with water.
• The well dug around the prefabricated building element can be immediately backfilled, which excludes landslides and possible subsequent collapse.

After the placement and backfilling of the well, all activities can be continued, without special precautions.

• rabattement de la nappe aquifère nul ou limité dans le temps;
• risques moindres lors du creusement du puits;
• aucune période d'attente pour la poursuite des activités de construction;
• étanchéité durable garantie;
• économie des coûts de fondation adjacentes ou voisines;
• possibilité de reprise de diverses charges et éléments de construction sans précautions particulières;
• utilisation de la dalle de sol comme dalle de fondation; et
• utilisation possible dans divers systèmes de fondation.

Given that the prefabricated building element combines all the advantages of a cellar made on the site itself (load-bearing function, integration into the whole construction of the building), as well as those of a prefabricated cellar known in this day (low cost price, very quick placement) and enjoys many other advantages including:

• drawdown of the aquifer zero or limited in time;
• lower risks when digging the well;
• no waiting period for the continuation of construction activities;
• guaranteed lasting watertightness;
• saving of adjacent or neighboring foundation costs;
• possibility of recovery of various loads and construction elements without special precautions;
• use of the floor slab as a foundation slab; and
• possible use in various foundation systems.

The realization of this prefabricated monolithic building element with load-bearing function is useful and economical. It embodies technical progress in the building industry.

Claims (11)

1. Precast reinforced concrete structural element, intended to serve as a cellar, consisting of a reinforced concrete shell (2) of any shape and dimensions, comprising a floor slab (3) and vertical walls, which are possibly equipped with a covering slab (5) provided with a trapdoor (5) for access to a staircase (6), characterised in that the floor slab (3) extends beyond the vertical walls (4).
2. Precast structural element according to Claim 1, characterised in that the vertical walls (4) are widened towards the bottom in order to enable the precast structural element to be removed from the mould in its entirety.
3. Precast structural element according to Claim 2, characterised in that the floor slab (3), which projects by at least 20 cm with respect to the walls (4), is a foundation slab making it possible to take up the dead weight of the precast structural element (1), of the annexes and of the loads applied to the precast structural element (1).
4. Precast structural element according to Claim 3, characterised in that the floor slab (3) is a foundation slab, so that all the loads applied to the precast structural element (1), including the dead weight, are transmitted, without deformation of the floor slab (3), to the subjacent bearing ground.
5. Precast structural element according to any one of the preceding claims, characterised in that it can accommodate structural elements such as columns and/or beams (16), which are fixed with the aid of anchoring means (17) to the walls, so as to form an assembly which is monolithic with the cellar and the building.
6. Precast structural element according to one of the preceding claims, characterised in that it is produced monolithically and without welding, so as to be completely watertight.
7. Method for producing a precast structural element according to Claim 1, by pouring prepared concrete into a mould (7), characterised in that the mould (7) is placed in an upside-down position while making sure that the floor slab (3) extends beyond the vertical walls (4).
8. Method according to Claim 7, characterised in that use is made of a pyramidal distribution hopper (9) for pouring the prepared concrete into the mould placed in an upside-down position and subjected to the action of the vibrators (8).
9. Method according to Claim 8, characterised in that the mould (3) containing the freshly cast concrete is lifted and tilted into the use position by means of a lifting and tilting machine (11) equipped with hydraulic motors and with gyration rings (12).
10. Method according to Claim 9, characterised in that the lifting and tilting machine (11) is mounted on wheels and conveys the mould (3) towards a store where it is set down.
11. Method according to one of Claims 7 to 10, characterised in that the mould (3) is removed by slowly lifting, after unlocking, the clipped protection plate (10), so as to free the precast cellar element which rests on the protection plate (10) until after setting.

Images