EP0370888A1 - Method for the construction at low water of a foundation beam for a facing overlying a work such as a slope, a bank or the like, and foundation beam thus obtained - Google Patents

Abstract

The method consists in hooking aligned and joined flexible sheaths (20) beneath a swing bar, in lowering the swing bar until it rests on supports with its sheaths touching the bottom (23) of a trench, in pouring concrete into the sheaths in successive layers (31.1 to 31.4) and alternately in one direction (arrow F) and in the opposite direction (arrow G), in closing the sheaths and in unhooking them, and in moving the swing bar to the next location. <IMAGE>

Description

The present invention relates to a method for the construction or repair in low water of a foundation beam of a riprap covering a structure such as a bank, a pier or the like.

Until now, the foundation has been made up of hard rock blocks arranged next to each other and connected together. The weight of these blocks and their connection are essential to ensure that the structure is held.

The structure thus formed generally resists well to the stresses to which it is subjected by moving water: current, waves, whirlpools, tide ... whether it is sea water or water from sensitive rivers. at the tide.

However, its repair or its construction step by step raises major difficulties. First of all, a competent workforce is no longer in sufficient quantity, the working conditions are painful and tiring, the cost of repairing is too expensive. Then and above all, it is only possible to work economically when the water is uncovered, that is to say three to four hours per tide and never at the same time, which implies a practically permanent availability of the workforce.

The present invention aims to remedy these drawbacks by proposing the use of concrete, so that the concrete poured parts and not yet consolidated constituting the foundation beam are not deteriorated when the sea or the river water rises and covers them. In addition, it must be possible to arm the beam in order to improve the overall resistance.

Of course, the execution of this beam must be quick, efficient and inexpensive. It must be able to be interrupted without damage when the water rises. It should only require a reduced number of staff. The beam thus obtained in concrete must finally be solid, resistant and reliable.

For this purpose and in accordance with the invnetion, the low beam construction process of the foundation beam consists of:
- digging a trench,
- to hang under a lifter suspended from a lifting machine a plurality of flexible envelopes having a parallelepiped shape and arranged side by side in at least one row at a spacing such that when they are filled, their adjoining transverse walls are strongly pressed the against each other,
- lower the spreader until it rests on support means, such as trestles, so that the row of envelopes is housed in the trench by touching the bottom thereof when filling begins ,
- to introduce longitudinal reinforcements by crossing the transverse walls of all the envelopes of the row and leaving them protruding at least from the last to ensure the connection with the next row,
- pour concrete into the envelopes, in particular by means of a pump, to deposit a first layer in one direction from one envelope to the next in order to inflate the transverse walls in this direction, then a second layer in the direction opposite in order to inflate the other transverse walls and so on from level to level until filling is completed,
- close the envelopes at their upper part and unhook them from the lifter,
- To move this lifter longitudinally to put in place another row of envelopes aligned with that considered, the first envelope of this other row being pierced to receive the protruding ends of the reinforcements of the already cast row.

According to a particular embodiment, the method consists in rolling a skirt of each envelope located above the handles attached to the lifting beam, in order to allow the pouring of the concrete, and after filling, to crease and tighten the skirt on itself to form a twist and to tie this twist to close the corresponding envelope.

Advantageously, on the side of the slope of the riprap, transverse reinforcing elements are inserted into the envelopes filled before setting of the concrete, these reinforcing elements being intended to allow the connection of the beam with the protective layer of said riprap.

The invention also extends to the foundation beam obtained by implementing the above method.

The beam is then formed by a plurality of aligned sections of concrete filling flexible envelopes closed and separated from each other by the compressed walls of these envelopes, each section having, at the same level on one side, projecting transverse parts s 'fitting into hollow transverse parts of the adjoining section and, on the other side, hollow transverse parts, the projecting parts being separated on the same side, from one level to the next, by hollow parts.

All sections of wrapped concrete are crossed by common longitudinal reinforcement, at least one end of which protrudes.

Reinforcement elements can be inserted into the sections of wrapped concrete in order to project along the slope of the riprap for the connection of the foundation beam with the riprap.

Various other characteristics and advantages of the invention will also emerge from the detailed description which follows.

An embodiment of the object of the invention is shown, by way of nonlimiting example, in the accompanying drawing.

• - la figure 1 est une coupe transversale d'un ouvrage auquel la poutre de fondation de l'invention est appliquée,
• - la figure 2 est une perspective montrant une enveloppe souple utilisée pour constituer la poutre,
• - la figure 3 est une coupe verticale prise suivant la ligne III-III de la figure 2, lorsque la jupe de l'enveloppe est roulée.
• - la figure 4 est une coupe longitudinale partielle de la poutre finie,
• - la figure 5 est une perspective avec arrachement illustrant une première phase du procédé.
• - les figures 6 à 9 sont des coupes-élévations concernant les phases suivantes du procédé,
• - la figure 10 est une coupe transversale prise suivant la ligne X-X de la figure 9.

On this drawing :

• FIG. 1 is a cross section of a structure to which the foundation beam of the invention is applied,
• FIG. 2 is a perspective showing a flexible envelope used to form the beam,
• - Figure 3 is a vertical section taken along line III-III of Figure 2, when the envelope skirt is rolled.
• FIG. 4 is a partial longitudinal section of the finished beam,
• - Figure 5 is a cutaway view illustrating a first phase of the process.
• - Figures 6 to 9 are sectional elevations concerning the following phases of the process,
• - Figure 10 is a cross section taken along line XX of Figure 9.

In the example shown, the structure to which the method of the invention applies is a pier 1 on which is built a roadway 2 bordered at least on one side by a sidewalk 3 and a concrete parapet 4. The pier is constituted in the form of a slope with the natural terrain 5 which is covered by a riprap 6. The sloping surface 7 of the riprap which connects the circulation surface of the carriageway 2 to the bottom 8 of the river or the sea, is coated with a riprap 9 whose foot abuts a foundation 10. The bottom of the riprap 9, the foundation 10 and the neighboring part of the bottom 8 are covered by a reinforcing embankment 11 intended to protect this area from the devastating action of the sea or the river. The water level on the river rises and falls with the tides and this movement of ebb and flow, is added that of waves, eddies, currents ... At low tide, the river 9 and the foundation 10 are discovered and there are then only three to four hours to work "dry".

As shown in Figure 5, to rebuild the foundation 10, a trench 11 is dug at the foot of the slope and a lifter 12 extending in line with the trench, is suspended from a lifting device 13. The lifter is made by two beams 14 connected by crosspieces 15 and delimiting between them windows 16 through which the pipe 17 of a concrete pump 18 can pour concrete as is indicated in the following.

As is now apparent from FIG. 6, hooks 19 are fixed to the outside of the side members 14 of the lifter 12 opposite the crosspieces 15. Flexible envelopes 20 are hung on the lifter and their dimensions are such, relative to the spacing of the hooks 19, that they retain, in pendant, their parallelepiped shape and that they touch by their transverse walls; however, due to their flexibility, they can deform and the deformation of each of the transverse walls is transmitted without breaking the contact with the contiguous transverse wall.

Trestles 21 (FIGS. 5 and 7) are installed on the ground to receive the lifter 12 when it is lowered to its lower level. In this position, the bottoms 22 of the envelopes 20 rest on the bottom 23 of the trench 11 and said transverse walls of these envelopes remain in contact. It is important that the envelopes remain suspended from the spreader, but they can take a slight "slack" to be sure that their bottoms rest on that of the trench, their transverse walls being always in contact despite this slight slack.

These envelopes 20 can be of the type shown in Figures 2 to 4. They can be made of woven polypropylene fabric. They have a parallelepiped shape and have two transverse walls 24, 25 and two longitudinal walls 26, 27 connected together and with the bottom 23. In the upper corners, straps are formed in a U and fixed by their branches on the two adjoining walls in order to constitute suspension handles 28 intended to be threaded on the hooks 19. Said walls 24 to 27 of the envelopes are extended, by a skirt 29 capable of being pleated and tightened on itself, the twist thus formed being capable of 'be tied in 30 to close the corresponding envelope.

As shown in Figures 3 and 7, the envelopes 20 of this type or another being suspended from the lifter 12 which rests on the trestles 21, the skirts 29 are rolled on themselves to form a roller 31 completely releasing the mouth said envelopes; it is also possible to fold the transverse walls 24, 25 and fold the longitudinal walls 26, 27 down and out.

As indicated in the foregoing and as can be seen from FIGS. 4 and 8, concrete is poured into the casings 20 by means of the concrete pump 18. However, this pouring takes place in successive layers, sometimes in one direction ( arrow F), sometimes in the opposite direction (arrow G).

More specifically, if we consider Figure 8, the envelopes being designated by the references 20.1 to 20.n from left to right, a first layer of concrete 32.1 is poured in the direction of arrow F of the envelope 20.1 up to envelope 20.n; the wall 25 of the envelope 20.i during casting then deforms towards the outside and pushes back the wall 24 of the following envelope 20.i + 1; it follows that in each envelope, the layer 32.1 of concrete has a projecting transverse part 33 on the right and a hollow transverse part 34 on the left, the projecting parts fitting into the hollow parts.

A second layer of concrete 32.2 is poured in the direction of arrow G from the envelope 20.n to the envelope 20.i; it is now, the wall 24 of each envelope 20.i during casting which deforms towards the outside and pushes back the wall 25 of the following envelope 20.i-1; as a result, in each envelope, the layer 32.2 has a projecting transverse part 35 on the left and a hollow transverse part 36 on the right, respectively surmounting a hollow part 34 and a solid part 33 of the underlying layer 32.1 and s' fitting respectively into a hollow part 36 and a projecting part 35 of the neighboring envelopes 20i-1 and 20 i + 1 of the same layer.

A third layer 32.3 is poured in the direction of arrow F, then a fourth layer 32.4 is poured in the direction of arrow G.

The protruding and hollow parts thus formed overlap one another by alternating from layer to layer. the following and it follows that the sections of enveloped concrete 37 are perfectly interconnected and are separated from each other only by the flexible walls 24 and 25 strongly tightened by the hydrostatic pressure of the concrete.

Furthermore, reinforcements 38 are slid into the row of bags 20, preferably before pouring the concrete. In the example shown, these frames are three in number. They extend over the entire length of the row passing through small openings made in the transverse walls of the envelopes and protrude by at least one of their ends 39 the last envelope of the row considered to penetrate during the construction of the next row in the first envelope thereof and thus ensure a solid connection, after pouring and consolidation of the concrete, of the two rows aligned with each other.

As FIGS. 4 and 9 now show, each envelope 20 is detached from the lifter 12 and its skirt 19 is then unrolled, pleated and tightened on itself in order to form the aforementioned twist intended to be knotted at 30 to close the envelope considered and subtract the section of concrete 39 corresponding to the action of water when said section is submerged, this action being particularly devastating as long as the concrete is not set and perfectly consolidated. Of course, other closure means such as adhesive tape, hook-and-loop tape, staples, etc. can be used.

The lifter 12 is then moved to the next location above the trench 11 to build the row which extends the one thus built.

It is important to note moreover that the flexibility of the envelopes 20 combined with the particular technique of concreting makes it possible to embed the sections 37 well one inside the other and to ensure a perfect seat of the beam thus formed on the bottom of the excavation. or trench 11 and possibly against the sides thereof.

Furthermore, and as can be seen from FIG. 10, reinforcing elements 40 can be inserted transversely into the sections of the wrapped concrete 37 in order to project parallel to the sloping surface 7 of the riprap and to ensure the connection of the foundation beam with the riprap 9 whatever its method of construction.

Claims (6)

1.- Method for the construction in low water of a foundation beam (10) of a riprap (9) covering a structure (1) such as a bank, a pier or other, consisting in digging a trench (11 ) to accommodate the beam, characterized in that it also consists of:
- To hang under a lifter (12) suspended from a lifting device (13) a plurality of flexible envelopes (20) having a parallelepiped shape and arranged side by side in at least one row at a spacing such as during their filling , their adjoining transverse walls (24, 25) are strongly pressed against each other,
- lower the lifter (12) until it rests on support means (21), such as trestles, so that the row of envelopes is housed in the trench (11) by touching the bottom (23) thereof when filling begins,
- to introduce longitudinal reinforcements (38) by crossing the transverse walls (24, 25) of all the envelopes (20) of the row and letting them protrude (at 39) at least from the last to ensure the connection with the row next,
- pouring concrete into the envelopes, in particular by means of a pump (18), to deposit there a first layer (32.1) in one direction (arrow F) from one envelope (20) to the next in order to inflate ( in 33) the transverse walls (25) in this direction, then a second layer (32.2) in the opposite direction (arrow G) in order to inflate (in 35) the other transverse walls (24) in reverse and so on from level to level until filling is complete,
- to close (at 30) the envelopes at their upper part and unhook them from the lifter,
- To move this lifter (12) longitudinally to put in place at the end another row of envelopes aligned with that considered, the first envelope of this other row being pierced to receive the protruding ends of the reinforcements of the already cast row. 2.- Method according to claim 1, characterized in that it consists in rolling a skirt (29) of each envelope (20) located above the handles (28) attached to the lifter (12), in order to allow the casting of concrete, and after filling, unroll the skirt, then pleat and tighten it on itself to form a twist and tie this twist (at 30) to close the corresponding envelope. 3.- Method according to claim 1 or 2, characterized in that on the side of the slope of the riprap, transverse reinforcing elements (42) are inserted into the envelopes filled before setting of the concrete, these reinforcing elements being intended to allow the connection of the beam with the protective layer of said riprap. 4.- Foundation beam of the foot of the riprap of a structure such as a bank, a pier or other, obtained by the implementation of the method according to claim 1 or 2 and characterized in that it is constituted by a plurality of aligned sections of concrete filling flexible envelopes closed and separated from each other by the compressed walls of these envelopes, each section having, at the same level on one side, protruding transverse parts fitting into hollow transverse parts of the contiguous section and, on the other side, hollow transverse parts, the projecting parts being separated on the same side, from one level to the next, by hollow parts. 5. Beam according to claim 4, characterized in that all the sections of enveloped concrete are crossed by common longitudinal reinforcements of which at least one end projects. 6. Beam according to claim 5, characterized in that reinforcing elements are inserted into the sections of wrapped concrete so as to project along the slope of the riprap for the connection of the foundation beam with the riprap.

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