EP0833987B1 - Continuously reinforced diaphragm wall, method of construction and formwork therefor - Google Patents

Description

The present invention relates to a molded frame wall continuous, a process for producing such a wall molded into the ground, and a formwork for producing such a molded wall.

The diaphragm walls are works that are carried out in the ground by digging a trench and filling this trench with a binder, to know in general concrete, which sets in situ.

The trench can be dug under a mud which is then replaced by the binder.

To obtain good continuity of the diaphragm wall, the binder must be poured all at once over the entire height of the trench.

For this purpose, the diaphragm wall is produced by adjoining panels successive.

Each panel is obtained by pouring the binder in a section of trench dug in the extension of a solidified panel previously realized.

The panels are connected two by two by mutual embedding their lateral ends, the shape of which is defined by a formwork, also referred to as an end joint, extending transversely to the trench over the entire depth of the latter and put in place before to pour the binder.

In general, a diaphragm wall is reinforced by reinforcements that we put in place in each section of trench before pouring the binder.

However, in such a molded wall, the reinforcements are missing at the connections between panels, which connections therefore constitute zones of weakness in the diaphragm wall, so that the transmission of the effects, in particular of transverse bending but also of longitudinal compression and traction, is not properly secured from panel to panel, which can cause problems with ground movements, especially in areas with strong seismic activity.

Document FR-A-2 517 717 describes a solution to this problem. It consists in fixing, at the ends of the armatures, panels, vertical sheet pile elements fitted with locks which cooperate with each other to ensure the continuity of the reinforcement of a panel to another.

However, this solution does not provide transmission the forces applied to the reinforcements under the effect of external constraints.

In addition, the engagement of the locks in each other becomes not very easy in case of misalignment of the reinforcements between them.

Finally, the means which are provided to protect the locks when the molding material is poured into the trenches is not really satisfying.

A first object of the invention is to provide a diaphragm wall constituted by several juxtaposed panels which allows in particular to obtain a good distribution of the forces applied to the armatures of different panels and that of an improved implementation.

To achieve this object, according to the invention, the diaphragm wall constituted by a succession of panels joined by their ends lateral and produced by pouring a binder in sections of trenches contiguous dug in the ground in the extension of each other, each panel comprising a frame, said wall comprising, in addition, connecting means ensuring mechanical continuity between two adjoining panels, is characterized in that the connecting means are separated from said frames and include an anchoring element having a first end provided with at least a first vertical locking element and a nested second end in the frame of one of said panels, and a connecting element having a first end provided with at least a second locking element capable of cooperating with the first element of locking and a second end nested in the frame of the other of said panels.

Another object of the invention is to provide a method of production of a diaphragm wall, in particular of the type defined above, and which does not have the drawbacks of the prior art.

To achieve this object, according to the invention, the method for carrying out in the ground a diaphragm wall according to which a first section is produced of trench in which an end formwork is placed and a binder to obtain a first wall panel, then we realize, on the side formwork, a second section of trench adjoining the first and in the extension of this, we remove the formwork and we pour a binder in the second section of trench to obtain a second panel of wall attached to the first, is characterized by the fact that before pouring the binder in the first section of trench, we put in place a reinforcement and a connecting element ensuring mechanical continuity having locking ends which are positioned at immediate vicinity of the formwork and that, when it is poured, it prevents the binder coming to drown said fixing ends so that they protrude from the first wall panel in the second section of trench after removing the formwork and before pouring the binder into the second section of trench, we put in place a reinforcement and a anchoring element which is secured to the locking ends of the connecting element and in that the formwork is secured to the element of connection before its installation in the trench section, the elements of connection and anchoring not directly attached to the reinforcements but being nested within them.

A third object of the invention is to provide a set comprising a formwork and a connecting element for making trench a diaphragm wall, in particular of the type defined above, which does not does not have the drawbacks of the state of the art.

To achieve this object, according to the invention, the assembly comprising a formwork and a connecting element having a first end provided with at least one locking element and a second end intended to be nested in the frame of a panel. diaphragm wall for the realization of a wall molded of the type defined above intended to be placed against a end wall of a section of trench dug in the ground for obtain a wall panel by pouring a binder in this section of trench, said formwork comprising a bearing face against the wall end of the trench section and, opposite this bearing face, a molding face directed towards the inside of the trench section, and the formwork has, on its molding face, at least one recess capable of receiving the locking element of the connecting element placed in the trench section, each recess being closed by a vertical wall element provided with a vertical slot suitable for passing a sheet pile element provided with the element interlocking and sealing between said sheet pile element and the wall of said recess.

• les figures 1 à 6 illustrent le principe de l'invention en montrant les différentes étapes de réalisation de deux panneaux contigus de paroi moulée ;
• les figures 7 et 8 montrent en vue de dessus et en vue en élévation un mode préféré de réalisation d'une armature d'un panneau et d'un élément d'ancrage ;
• la figure 9 montre la liaison entre les armatures de deux panneaux de la paroi moulée ;
• la figure 10 montre en coupe verticale un mode de réalisation préféré du coffrage dans le cas où il y a une seule serrure ;
• la figure 11 est une vue de détail de la figure 10 ; et
• les figures 12 et 13 montrent en coupe verticale des variantes de réalisation du coffrage.

Other characteristics of the invention will appear better on reading the following description of several embodiments of the invention given by way of nonlimiting examples. The description refers to the appended figures in which:

• Figures 1 to 6 illustrate the principle of the invention by showing the different stages of production of two contiguous diaphragm wall panels;
• Figures 7 and 8 show in top view and in elevational view a preferred embodiment of a frame of a panel and an anchoring element;
• Figure 9 shows the connection between the frames of two panels of the diaphragm wall;
• Figure 10 shows in vertical section a preferred embodiment of the formwork in the case where there is a single lock;
• Figure 11 is a detail view of Figure 10; and
• Figures 12 and 13 show in vertical section alternative embodiments of the formwork.

Referring first to Figures 1 to 6, we will describe the principle of production of the diaphragm wall according to the invention.

In Figure 1, there is shown the digging of a section of trench 20 in the soil under mud using a suitable device, for example example a bucket.

An element is placed in the trench section of metal reinforcement 22 which will be described later in more detail and a connecting element 24 integral with a formwork element 26 intended for limit the length of panel that will be produced. The connecting element 24, which will be described in more detail later, is nested in the frame 22 but is not welded thereon. By nesting, it is necessary hear that part of the connecting element enters inside the cage that constitutes the frame. The connecting element 24 ends with two locks 28 and 30 which are arranged in two housings 32 and 34 of the formwork element 26. These recesses are closed by means which will be described later. These means are intended avoid, when pouring the binder (concrete or grout), that this material don't coat the locks. In addition, these means temporarily unite the connecting element 24 and the formwork element 26.

In the next step shown in Figure 3 the concrete or grout is poured into trench 20 to make a panel 36. The panel is reinforced by frame 22. In addition, it provides the connection mechanical between the armature 22 and the connecting element 24 which are embedded in concrete. However, thanks to the housings 32 and 34, the locks 28 and 30 remain free. In addition, as is known, the element of formwork 26 has a general U-shape in horizontal section of such so that the panel 36, after removal of the formwork the end 38 of the panel has a form of embedding of the next panel. The locks 28 and 30 protrude in the form 38 of embedding.

Before removing the formwork, a second dig is dug section of trench 40 in which the second panel of the diaphragm wall.

In the trench section 40, we simultaneously put in place a metal frame 42 and an anchoring element 44, the element anchor 44 being nested in the frame 42 but not welded in this one. When the anchoring element 44 is put in place, the locks 46 and 48 thereof are engaged in locks 28 and 30 of the connecting element 24 of the panel 36 already produced. This commitment of locks between them is greatly facilitated by the fact that the element anchor 44 is not fixed to the frame 42, the anchor element can be moved horizontally relative to the reinforcement around the plane vertical median of the reinforcement.

When this installation is finished, we proceed to the casting concrete or grout in the trench section 40 to carry out the second panel 50 of the diaphragm wall.

We understand that thanks to the attachment of the connecting elements 24 and anchor 44, there is provided between the two panels a continuity of mechanical resistance of metal reinforcement elements. Indeed, although there is no direct mechanical connection, for example by welding, between the reinforcements 22 and 42 and the assembly constituted by the connecting element 24 and the anchoring element 44, the nesting of these reinforcing elements which are embedded in the concrete ensures continuity mechanical.

Referring now to Figures 7 and 8, we will describe a preferred embodiment of the frames 22, 42 and the elements of link or anchor 24 and 44.

The frame 22 is usually formed by a cage formed by horizontal concrete bars 52 and vertical concrete bars 54 welded together.

According to a preferred embodiment, the connecting element 24 (or the anchoring element 44) is constituted by U-shaped round irons referenced 56. Irons 56 (56a, 56b, 56c) are arranged in planes regularly spaced horizons. For example, for a frame of 12 meters high, the irons 56 are spaced 66 centimeters apart. The free ends 58 and 6U of the arms of the irons 56 are respectively welded on sheet pile elements 62 and 64 which end in the locks 28 and 30 (or 46 and 48). Optionally flat irons horizontal 66 can be welded at regular intervals between the sheet piles 62 and 64.

It is understood that the connecting or anchoring elements are essentially constituted by round irons in the shape of horizontal U joined together by sheet piles. U-shaped irons are nested in the irons forming the reinforcements but not integral with them.

We would not depart from the invention if the connecting elements or anchors were formed differently. It is important, however, that they are essentially made up of horizontal concrete bars so to promote the horizontal transmission of the forces likely to be applied to panels and therefore to their frames.

It also goes without saying that the locking elements of the anchors and connecting elements could be formed by means other than sheet pile type locks. It is enough that they constitute male and female locking members capable of cooperating between them when placing a reinforcement in a section of trench.

Figure 9 shows a top view of the locking of an element 24 and an anchor 44, the concrete not having been shown for ease of understanding.

FIG. 7 also shows the formwork element 26 with its two housings 32 and 34 in which are "enclosed" the locks 28 and 30. The preferred embodiment of the formwork element 26 will be described in conjunction with Figures 10 and 11.

In FIG. 10, a formwork element 26 ′ has been shown in the case where the connecting element 24 'has only one lock 28.

The formwork 26 'proper is provided on its molding face 70 of two metal parts 72 and 74 which define between them a housing or recess 76 having an opening 78. Housing 76 has sufficient dimensions to receive the lock 28 arranged at the end of the vertical sheet pile element 80. The opening 78 is closed by two rigid wall portions 82 and 84 which leave between them a slot 86 whose width is slightly greater than the thickness of the sheet pile 80, the wall portions 82 and 84 being fixed on the parts 72 and 74. The slot 86 is closed by flexible sealing lips 88 and 90 fixed on the walls 82 and 84. These lips 88 and 90 are supported by elastic deformation on the faces of the sheet pile 80 thus ensuring sealing against the binder.

Rigid walls 82 and 84 achieve horizontal positioning of the connecting element 24 and a temporary fastening of the formwork 26 on element 24.

To further improve the seal, you can mount inside of the housing 76 two vertical flexible pipes 90 and 92 which are in contact with the lock, the wall portions 82 and 84 and the internal wall housing. A second sealing system is thus produced.

These flexible pipes can also be used for carry out a circulation of water to "clean" the locks, after pouring grout or concrete if a small amount of this product is happened to enter the accommodation.

Figures 12 and 13 show alternative embodiments of the means for sealing the housing or housings in the formwork elements.

In the case of the embodiment of FIG. 12, the locks 28 and 30 are protected in housings 32 and 34 by covers in rubber 100 and 102.

In the case of the embodiment of FIG. 13, the locks 28 and 30 are protected by slotted tubes 104 and 106 which are threaded on locks. Even if after removing the formwork 26, a envelope by binding around the tubes 104, 106 these envelopes are easily destroyed by the placement of element locks the next panel.

Claims (7)

1. A cast wall constituted by a succession of panels (36, 50) touching via their end edges and made by casting a binder into contiguous lengths of trench (20, 40) dug in the ground in line with one another, each panel having one reinforcement (22, 42), said wall further including link means (24, 44) ensuring mechanical continuity between two contiguous panels, the wall being characterized in that the link means are separated from said reinforcement and comprise an anchor element (44) having a first end fitted with at least one vertical first locking element (46, 48) and a second end engaged in the reinforcement of one of said panels, and a link element (24) having a first end fitted with at least one second locking element (28, 30) suitable for co-operating with the first locking element, and a second end engaged in the reinforcement of the other of said panels.
2. A cast wall according to claim 1, characterized in that each anchor element (44) and each link element (24) comprises a plurality of bars disposed substantially in horizontal planes, the free ends of the bars being secured to a lock-forming sheet piling type element (62, 64), at least a portion of the bars being engaged without direct mechanical linking in the end portion of the reinforcement of the panel.
3. A cast wall according to claim 1, characterized in that said bars are U-shaped round bars disposed in horizontal planes, at least one limb of each U-shaped bar being secured to a lock-forming sheet piling element, at least the curved portion of the U-shaped round bar being engaged in the end portion of the reinforcement of the panel without being directly mechanically linked.
4. A method of making a cast wall in the ground in which a first length of trench (20) is prepared in which an end shuttering (26) is placed and a binder is cast to obtain a first wall panel (36), and then, at the shuttering end, a second length of trench (40) is prepared contiguous to the first and in line therewith, the shuttering (26) is removed, and a binder is cast into the second length of trench to obtain a second wall panel (50) adjacent to the first, which method is characterized by the fact that, prior to casting the binder in the first length of trench, reinforcement (22) is placed therein together with a link element (24) ensuring the mechanical continuity and including locking ends (28, 30) that are positioned in the immediate vicinity of the shuttering (26), and during casting, said locking ends are prevented from being embedded in the binder so that they project from the first wall panel (36) into the second length of trench (40) after the shuttering has been removed, and prior to casting the binder in the second length of trench, reinforcement (42) is put into place therein together with an anchor element (44) which is secured to the locking ends of the link element (24), and in that the shuttering (26) is secured to the link element (24) prior to being put into place in the length of trench, the link and anchor elements (24, 44) not being directly secured to the reinforcement, but being engaged therein.
5. Assembly comprising a shuttering (26) and a link element (24) having a first end provided with at least one locking element and one second end designed to be engaged in the reinforcement of a cast wall panel for making a cast wall according to claim 1 or 2, and designed to be put into place against an end wall of a length of trench dug in the ground to obtain a wall panel by casting a binder into said length of trench, said shuttering including a face for bearing against the end wall of the length of trench, and opposite said bearing face, a casting face looking into the length of trench, assembly according to which the shuttering includes on its casting face, at least one recess (32, 34, 76) suitable for receiving the locking element of the link element placed in the length of trench, each recess being closed by a vertical wall element provided with a vertical slot (86) suitable for letting in a sheet piling element fitted with the locking element and providing sealing between said sheet piling element and the wall of said recess.
6. Assembly according to claim 5, characterized in that said vertical wall element includes two vertical wall portions (82, 84) secured to the wall of said recess (32, 34, 76) and leaving between them said vertical slot (86), and two resilient sealing elements (88, 90) respectively secured to said vertical wall elements, said sealing elements forming sealing lips pressed resiliently against the faces of said sheet piling element.
7. Assembly according to claim 6, characterized in that it further includes two portions of vertical hose (90, 92) disposed in said recess (32, 34, 76), each hose portion being in contact with the wall of the recess, the inside face of one of the two portions (82, 84) of vertical wall, and one face of the locking element.

Images