GB2216933A - Retaining wall composed of prefabricated concrete elements - Google Patents

Abstract

A retaining wall of the caisson-wall type is composed of prefabricated concrete elements and comprises transverse walls (2a, 2b), which are buried in the embankment; facing slabs (6), which are engaged in notches in the walls and I-shaped joggles (8a, 8b) which are placed in housings defined by two half-notches. The invention is particularly applicable to the construction of retaining walls having a height of some metres. <IMAGE>

Description

RETAINING WALL OF THE CAISSON-WALL TYPE COMPOSED OF PREFABRICATED CONCRETE ELEMENTS The present invention relates to retaining walls of the caisson-wall type composed of prefabricated concrete elements.

The technical sector of the invention is that of public works.

Caisson-walls are already known, composed of pre-fabricated concrete elements, where plants may be grown since the embankment forms visible banks on the front face thereof.

French Patent 78/09686 to ENTERPRISE ALBERT PELLER et CIE describes sound-insulating walls which are composed of transverse beams and of longitudinal beams intersecting therewith which form two continuous anchorages and the longitudinal beams located at the front of the wall have a trough-shaped section. The transverse and longitudinal beams frame rectangular wells filled with earth.

French Patent 77/35113 to Jean OLIVIER describes caisson-walls which comprise pre-fabricated facade panels whose rear face is extended by two parallel transverse walls.

French Patent 79/13283 to R. BARGE et al describes caisson walls composed of pre-fabricated elements which comprise facade panels extended to the rear by two transverse vertical walls, which have rear edges forwardly and upwardly inclined and which further comprise a rear slab supported on the inclined edges of the transverse walls.

French Patent 78/16804 to SABLA describes caisson walls which comprise transverse walls composed of beams placed one above the other; upwardly and outwardly inclined facade plates which are placed in notches in the transverse beams and transverse bars or beams which connect the rear ends of the beams.

All the walls described in these prior art documents are composed of relatively heavy pre-fabrica ted elements which require the use of handling machines for positioning them. Moreover, the shapes of these pre-fabricated elements are often complex and require expensive moulds for pre-fabrication.

It is one object of the present invention to provide caisson-walls, composed of pre-fabricated concrete elements, which have very simple shapes, without draft, with the result that they may be prefabricated in elongated moulds such as those used for example for prefabricating pavement curbs or fencing posts.

Another object of the present invention is to provide caisson-walls composed of light elements which may be manipulated and positioned by hand.

The retaining walls according to the invention are caisson-walls of the known type comprising parallel transverse walls which are embedded in the embankment and which are constituted by identical beams, prefabricated in reinforced concrete, which are superposed, and facing slabs, pre-fabricated in reinforced concrete, which are placed in notches in two beams located at the same level and which are inclined upwardly and outwardly.

The objects of the invention are attained by means of caisson-walls in which each of the beams comPrises, near its rear end, two half-notches located such that two half-notches of two superposed beams are superposed to form a rectangular housing and the walls further comprise joggles made of prefabricated concrete, in I-form, of which the web is engaged in one of said rectangular housings and of which the flanges project on either side of said beams.

The concrete joggles are advantageously placed flat.

According to a preferred embodiment, the con crete joggles are commercially available self-blocking pavings.

The invention results in novel walls of the caisson-wall type composed solely of three categories of pre-fabricated concrete elements: beams, facing slabs and joggles.

The beams and slabs are very simple in shape.

They are elongated elements of rectangular section, with no draft, nor any part in relief on the lateral faces. This results in that the beams and slabs may be prefabricated with known prefabrication machines of the type such as those currently used for making concrete curbs or posts. As to the I-shaped joggles, commercially available self-blocking pavings may advantageously be used.

The walls according to the invention are composed of elements whose unitary weight is of the order of 50 kg, with the result that they may be manipulated and positioned by two men without the aid of any hoisting or handling machine.

The caisson-walls according to the invention are particularly adapted for constructing retaining walls having a height of the order of some metres.

The invention will be more readily understood on reading the following description with reference to the accompanying drawings, in which: Fig. 1 shows a first phase of the construction of a caisson-wall according to the invention.

Figs. 2 and 3 show the following phases of construction.

Fig. 4 is a plan view of a section of caissonwall according to the invention.

Fig. 5 is a vertical section along V-V of Fig.

4.

Fig. 6 is a plan view of a fragment of paving constructed of self-blocking I-shaped paving stones.

Referring now to the drawings, Fig. 1 shows the first phase of the construction of a cell of a caisson-wall according to the invention.

This wall comprises a plurality of juxtaposed identical cells.

A sole plate 1 intended to support the wall is firstly made on the ground.

Two identical beams 2a, 2b, which are parallel to each other, are then placed on this sole plate.

Beams 2a, 2b are prefabricated in reinforced concrete.

They present an elongated rectangular shape without an draft. Their length is of the order of one to two metres. These beams are cast on conventional machines in moulds of the type used for prefabricating pavement curbs. A prefabricated reinforcement is placed in the mould, then concrete is cast in the mould, which is vibrated and compressed.

1500 to 2000 beams may thus be prefabricated per day with one mould, this reducing costs. The beams thus obtained are perfectly dimensioned and can be well stacked.

Beams 2a, 2b are placed on edge. Each beam comprises, near its front end, a transverse notch 3a, 3b adapted to receive a prefabricated slab.

Each beam 2a, 2b comprises, near its rear end, two transverse half-notches, a half-notch 4a, 4b on its lower face and a half-notch 5a, 5b on its upper face.

When the two beams are superposed, the halfnotches 4 superpose on half-notches 5 to form a transverse rectangular housing.

Fig. 2 shows the following step, during which there is positioned in notches 3a, 3b in two adjacent beams a rectangular facing slab 6 made of reinforced concrete, which comprises on its lower edge and on its upper edge, half-notches 7 whose width is slightly larger than the thickness of the beams 2a, 2b. The length of the slabs 6 is equal to twice the distance between two beams and the distance between each halfnotch 7 and the end of the most adjacent slab is equal to half the distance between two beams.

Slabs 6 are prefabricated on high-vibration machines with a weakly watered concrete, with the result that a very compact concrete is obtained, perfectly adapted to working in simple flexion.

There are placed in the half-notches 5a, 5b, joggles 8a, 8b which are prefabricated concrete pavings in the form of an I. The web of the I is positioned in the housing defined by a half-notch 5 and hy the half-notch 4 in the beam superposed thereon.

The thickness of the joggle is slightly smaller than the combined depth of a half-notch 5 and a halfnotch 4. The length of the web of the joggle is slightly larger than the thickness of the beams, with the result that the flanges 9 of the joggles project on either side of the beams.

The joggles 9 perform a first function, that of joining the rear ends of the superposed beams 2 both in the longitudinal direction of the beams by the web of the joggles and in the direction transverse to the beams by the flanges of the joggles. In this way, the superposed beams which are also joined together at their front end by the slabs 6, are maintained perfectly superposed in order to form transverse walls buried in the embankment.

The joggles 8a, 8b perform another function: The embankment located inside the wall abuts on the flanges of the joggles which project between the pairs of vertical walls formed by the superposed beams 2a, 2b. These projecting parts serve as anchoring point for the formation of vertical embankment arches, opposing upsetting of the wall.

Fig. 3 shows a subsequent phase of the construction during which two new beams 2'a, 2'b are positioned above beams 2a, 2b, and the same operations are continued until the wall has attained the desired height.

Thereafter the embankment located to the rear of the wall is pushed towards said wall, forming small banks which are retained by the facing slabs 6 and which are visible between said slabs, with the result that plants can be grown on these banks.

Slabs 6 may be prefabricated by means of automatic machines of the type used for manufacturing fencing posts. Such a machine, in which from four to nine pieces may be cast per mould, enables 300 slabs to be prefabricated per day.

Slabs 6 may also be prefabricated on devices of the turn-up trestle type.

Joggles 8a, 8b are advantageously constituted by commercially available self-blocking pavings.

The elements constituting the walls according to the invention may therefore be easily prefabricated in small prefabrication units fitted with current equipment. With two moulds, one for the beams and the other for the slabs-, the elements necessary for constructing 150 m of wall may be prefabricated per day, for a reduced cost price.

The total weight of the prefabricated elements is of the order of 300 kg/m2 of wall and the unitary weight of each element is of the order of 50 kg, with the result that all the elements may be positioned manually.

The problem to be solved in this type of caissonwall is that of avoiding upsetting of the wall under the thrust of the embankment. Resistance to upsetting is obtained by the effect of the beams 2a, 2b which penetrate in the embankment and on which the weight of the embankment is exerted. However, if the thickness of the beams is reduced, the latter risk splitting the embankment. In order to increase resistance to upsetting, one has heretofore resorted either to beams comprising at their rear end a bulb-shaped swell, to caissons in which the rear ends of the beams are connected together by other beams which are perpendicular thereto, or to walls comprising inclined slabs at the rear.

The walls according to the invention propose a simplified solution in which a sufficient resistance to upsetting for walls having a height of some metres is obtained, solely by equipping the transverse partitions with joggles 8a, 8b which project between the transverse partitions, near the rear ends thereof and which abut on the embankment which surmounts them in order to oppose upsetting of the wall.

Fig. 4 shows a cell of a caisson-wall according to the invention seen from above and Fig. 5, a vertical section passing through the axis of a beam.

These two Figures show the beams 2a, 2'a, 2b, 2'b, the prefabricated slabs 6, comprising notches which cooperate with the notches 3a, 3b of the beams and the joggles 8a, 8b which are engaged in the housings constituted by two superposed notches 4 and 5.

Fig. 4 shows a preferred embodiment in which the I-shaped joggles 8a, 8b are commercially available, self-blocking pavings.

Figs. 4 and 5 show that the joggles 8a, 8b are placed flat like pavings on the ground, i.e. the web and the flanges 9 lie in the same horizontal plane which is that of the join between two superposed beams, with the result that the horizontal surface by which the joggles abut on the embankment for opposing upsetting of the wall, is maximum.

Fig. 6 shows a fragment of pavement constructed from self-blocking pavings, showing the geometrical shapes of these interfitting pavings.

Claims (4)

1. A retaining wall of the caisson-wall type comprising transverse, parallel, vertical walls which are embedded in the embankment and which are constituted by identical beams, prefabricated in reinforced concrete, which are superposed, and by facing slabs, prefabricated in reinforced concrete, which are placed in notches in two beams located at the same level and which are upwardly and outwardly inclined, in which each of the beams comprises, near its rear end, two half-notches, one on its lower face and the other on its upper face, with the result that two halfnotches of two superposed beams define a transverse rectangular housing in which a concrete joggle is engaged, wherein each of said joggles is in the form of an I which is placed flat in one of said notches, the web and the flanges of said joggle lying in the same horizontal plane which is the plane of the join between two superposed beams.

2. A retaining wall as claimed in Claim 1, wherein said joggles are self-blocking pavings placed flat.

3. A retaining wall as claimed in either one of Claims 1 and 2, wherein the thickness of said joggles is slightly less than the height of a notch.

4. A retaining wall as claimed in any one of Claims 1 to 3, wherein the length of the web of said joggles is slightly greater than the thickness of the beams and the flanges of the joggles project on either side of the beams.