GB2615084A

GB2615084A - Prefab concrete element for constructing a retaining wall

Info

Publication number: GB2615084A
Application number: GB2200998.9A
Authority: GB
Inventors: Ciers Henk; Benoit Bruno; Daems Joris
Original assignee: Cbs Beton NV
Current assignee: Cbs Beton NV
Priority date: 2022-01-26
Filing date: 2022-01-26
Publication date: 2023-08-02
Also published as: GB202200998D0

Abstract

A prefab concrete element for constructing a retaining wall comprising a wall 1, a foot 2 portions, and a reinforcing mesh, wherein the prefab concrete element has an L-shaped cross-section, and where the wall and foot are substantially perpendicular to each other. The foot is at least 1 cm shorter in the longitudinal direction at both ends than the wall. The wall may comprise a groove (fig. 1, 4) in the height direction in a first side and a tongue 13 on a second side opposite, wherein the groove and the tongue may be complementary. Both, the portions may comprise their own reinforcing mesh. The reinforcing mesh maybe folded in each portion, in the corner formed by foot and wall, in a u-shape and away from the other portion, wherein the folded portion of reinforcing forms a conduit. There may be a concrete reinforcement volume in the said corner.

Description

PREFAB CONCRETE ELEMENT FOR CONSTRUCTING A RETAINING WALL

TECHNICAL FIELD

The invention relates to a prefab concrete element for constructing a retaining wall.

PRIOR ART

Retaining walls are a well-known structure in architecture. Retaining walls are intended to compensate for stepped differences in height in a site. The purpose of the retaining wall is to retain higher ground or, in certain cases, water, so that lower ground can be used advantageously, without the risk of landslides or flooding by water.

Originally, retaining walls were built on site or concrete retaining walls were poured on site. In many cases, however, it is possible to construct a retaining wall using C\I prefab concrete elements. The prefab concrete elements can be manufactured in a C\I factory workshop under controlled conditions and assembled into a retaining wall on site. This is a more efficient and faster way of constructing retaining walls because standard prefab concrete elements are used, and the pouring of the prefab concrete elements is not dependent on weather conditions. C\I

A prefab concrete element according to the prior art is usually an L-shaped element. The known prefab concrete elements have a number of drawbacks. Firstly, the dimensions of the prior art prefab concrete elements are not always sufficiently accurate to allow the prefab concrete elements to link up closely. This creates a narrow gap between adjacent prefab concrete elements through which soil runs. Over time, this can lead to subsidence.

A prefab concrete element according to the prior art usually also comprises a simple reinforcement. The reinforcement is a single reinforcing mesh that is pleated in L-shape. In the corner formed by the two legs of the L-shape, the reinforcing mesh cannot absorb sufficient stresses in the concrete, as a result of which the outer corner of the prefab concrete element pops off. As a result, the retaining wall is again weakened and threatens to break. C\I

C

LO C\I

The present invention aims to find at least a solution to some of the above-mentioned problems.

SUMMARY OF THE INVENTION

For this purpose, the invention provides a prefab concrete element according to claim 1.

The major advantage of a prefab concrete element according to the present invention is that it comprises a foot and a wall portion, wherein the foot is at least 1 cm shorter than the wall portion at both ends. Even if the dimensions of the prefab concrete element are not carried out completely accurately, it is possible to construct a retaining wall wherein the wall portions of the prefab concrete elements link up accurately. There is no gap for soil to run through, which could lead to subsidence of the backfill over time.

Preferred embodiments of the device are set out in claims 2 to 14.

A particular preferred embodiment of the invention relates to a device according to claim 2.

According to this embodiment, the wall portion comprises a groove in a first side wall and a tongue on a second opposite side wall, wherein the tongue and groove are complementary. This is advantageous because when prefab concrete elements according to the present invention are placed next to each other, the tongue of a first prefab concrete element engages in the groove of a second prefab concrete element, so that a solid multiple barrier to soil in a direction transverse to the retaining wall is obtained at the junction between two prefab concrete elements.

DESCRIPTION OF THE DRAWINGS

Figure 1 shows a perspective view of a prefab concrete element according to an embodiment of the present invention.

Figure 2 shows a cross-sectional view of a prefab concrete element according to an embodiment of the present invention.

Figure 3 shows a perspective view of a prefab concrete element according to an alternative embodiment of the present invention.

DETAILED DESCRIPTION

Unless otherwise defined, all terms used in the description of the invention, including technical and scientific terms, have the meaning as commonly understood by a person skilled in the art to which the invention pertains. For a better understanding C\I of the description of the invention, the following terms are explained explicitly. C\I

In this document, "a" and "the" refer to both the singular and the plural, unless the context presupposes otherwise. For example, "a segment" means one or more segments. C\I

The terms "comprise", "comprising", "consist of", "consisting of", "provided with", "include", "including", "contain", "containing", are synonyms and are inclusive or open terms that indicate the presence of what follows, and which do not exclude or prevent the presence of other components, characteristics, elements, members, steps, as known from or disclosed in the prior art.

Quoting numerical intervals by endpoints comprises all integers, fractions and/or real numbers between the endpoints, these endpoints included.

In the context of this document, "surcharge load" is a load applied to higher ground that is restrained by a retaining wall. For example, with a surcharge load of more than 25 kN/m2 or heavy traffic in accordance with EN 1991-1:LM1 with 1 m edge distance, there is a high surcharge load.

In a first aspect, the invention relates to a prefab concrete element for constructing a retaining wall.

According to a preferred embodiment, the prefab concrete element comprises a wall portion, a foot and a reinforcing mesh. The prefab concrete element has an L-shaped cross-section, wherein a first leg is the foot, and a second leg is the wall portion. The first leg and the second leg are substantially perpendicular to each other. In this text, the width in the direction of the first leg, the height in the direction of the second leg and the length in a direction perpendicular to the L-shaped cross-section is defined.

An L-shaped cross-section is advantageous for constructing a retaining wall, wherein the wall portion stops higher ground and wherein the foot is positioned under the higher ground. The moment that the higher ground exerts on the prefab concrete element is compensated by the weight of the higher ground on the foot, so that the retaining wall does not fall over.

C\I The foot and the wall portion have a first and a second end in the longitudinal C\I direction. The foot is at least 1 cm shorter in the longitudinal direction at both ends CJ than the wall portion. This means that both ends of the foot fall within the length of the wall portion. Preferably, the foot is at least 1.5 cm shorter in the longitudinal direction at both ends, more preferably at least 2 cm shorter and even more C\I preferably at least 2.5 cm shorter. A dimension of a prefab concrete element has an accuracy of ± 0.5 cm. Because the foot is at least 1 cm shorter at both ends in the longitudinal direction than the wall portion, prefab concrete elements whose dimensions are not completely accurate, for example the length of the wall portions is 0.5 cm too short, link up accurately. This makes it possible to still construct a retaining wall, wherein there is no gap between wall portions of adjacent prefab concrete elements, through which soil can penetrate, leading to subsidence in the course of time.

Even if the dimensions of the prefab concrete element are not carried out completely accurately, it is possible to construct a retaining wall wherein the wall portions of the prefab concrete elements link up accurately. There is no gap for soil to run through, which can lead to subsidence over time. A prefab concrete element according to the present invention is advantageous for constructing robust retaining walls.

According to an embodiment, the wall portion comprises a groove in the height direction in a first side wall and a tongue on a side wall opposite in the longitudinal direction. The tongue and groove are complementary. The first and second side walls of the wall portion are part of the L-shaped cross-section of the prefab concrete element. The tongue and groove are preferably arranged over the full height of the prefab concrete element.

The tongue and groove have an isosceles triangular cross section, wherein the base of the isosceles triangle coincides with a side wall of the wall portion and the equal sides extend from the side wall of the wall portion. The equal sides have a length of at least 1.5 cm, preferably at least 2.0 cm and more preferably at least 2.5 cm. The perpendicular distance from the base of the isosceles triangle to the angle formed by the equal sides is at least 1.0 cm, preferably at least 1.5 cm. The tongue and groove preferably have an isosceles and rectangular cross section.

Alternatively, the tongue and groove have a semicircular cross section. The radius of C\I the semicircular cross-section is at least 1.0 cm, preferably at least 1.5 cm, more C\I preferably at least 2.0 cm. C\I

A tongue and groove are advantageous because when prefab concrete elements according to the present invention are placed next to each other, the tongue of a first C\I prefab concrete element engages in the groove of a second prefab concrete element, so that a solid multiple barrier to soil in a direction transverse to the retaining wall is obtained at the junction between two prefab concrete elements.

According to an embodiment, both legs of the prefab concrete element comprise their own reinforcing mesh. Both the foot and the wall portion have a separate reinforcing mesh. The reinforcing mesh of the foot extends over at least 80% of the width and length of the foot, preferably at least 85% and more preferably at least 90%. The reinforcing mesh of the wall portion extends over at least 80% of the width and height of the wall portion, preferably at least 85% and more preferably at least 90%. A reinforcing mesh is a grid of bars. The bars have a diameter of at least 6 mm, preferably at least 8 mm, more preferably at least 9 mm and even more preferably at least 10 mm. The reinforcing meshes of the foot and the wall portion preferably extend through each other. The reinforcing meshes are preferably connected to each other.

Both legs of the prefab concrete element having their own reinforcing mesh is advantageous for absorbing stresses in the prefab concrete element, in particular in the corner formed by the two legs of the L-shape. In a prior art single reinforcing mesh which is folded in an L-shape, the reinforcing mesh exerts a tensile force from a free end of the first leg towards the corner formed by the two legs of the L-shape and from a free end of the second leg to the corner formed by the two legs of the L shape. There is no tensile force through the single reinforcing mesh from the corner formed by the two legs of the L-shape to the free ends of the legs. As a result, there is a high stress in the concrete at the corner formed by the two legs of the L-shape.

This stress is further increased by the weight of the wall portion, which also exerts a force on the corner. There is a real risk that concrete will flake off in the corner and that the prefab concrete element will break.

By placing a reinforcing mesh in both the foot and the wall portion, there is a tensile force through the reinforcing meshes from the corner to the free ends of the legs.

Because the reinforcing meshes extend through each other, the reinforcing meshes C\I can penetrate deep into the corner of the prefab concrete element to absorb stresses. C\I

According to a further embodiment, the reinforcing meshes in each leg are folded, in the corner formed by the foot and the wall portion, over a distance of at least 10 cm, preferably at least 20 cm, more preferably at least 30 cm and even more preferably C\I at least 40 cm, in a U-shape and away from the other leg. The folded portions of the reinforcing meshes form a conduit.

The conduit is a substantially beam-shaped body. The beam-shaped body preferably has a square cross-section. The minimum dimensions of the conduit are determined by an effective height in the corner, measured from a reinforcing mesh in a leg to a side of the leg furthest from the reinforcing mesh, wherein the conduit is covered by at least 3 cm of concrete. One side of the square cross-section has a length of at least 6 cm, preferably at least 8 cm, more preferably at least 9 cm and even more preferably at least 10 cm.

The conduit is a rigid element which is advantageous for absorbing moments relative to an axis along the longitudinal direction and through the conduit. This is, for example, a moment caused by the force that higher ground exerts on the wall portion of the prefab concrete element. If this moment cannot be absorbed sufficiently in the concrete, the wall portion would twist with respect to the foot and crack and finally break at the corner formed by the wall portion and the foot.

Upon twisting of the wall portion relative to the foot, the concrete in an extreme corner formed by the wall portion and the foot is most compressed, making the concrete in the extreme corner prone to flaking and popping off. By folding the reinforcing meshes in each leg, in the corner formed by the footing and the wall portion, over a distance of at least 10 cm in a U-shape and away from the other leg, the reinforcing mesh is very close in the extreme corner and applies a tensile force toward a free end of a leg, which reduces the compression stress in the extreme corner and reduces the likelihood of flaking concrete.

According to an embodiment, the prefab concrete element comprises a concrete reinforcement volume in a corner, formed by the foot and the wall portion. The concrete reinforcement volume extends over the full length of the foot. The concrete reinforcement volume is bounded by the wall portion, the foot and a sloping wall. The C\I concrete reinforcement volume is a triangular prism. The triangular prism is C\I preferably cast together with the foot and the wall portion, so that the wall portion, the foot and the concrete reinforcement volume form a monolithic whole. The concrete reinforcement volume has a height of at least 9 cm, measured from the foot and according to the height direction. The concrete reinforcement volume has a width C\I of at least 9 cm, measured from the wall portion and according to the width direction.

The concrete reinforcement volume is advantageous for diverting some of the weight from the wall portion to the foot, away from the corner formed by the wall portion and the foot.

According to a further embodiment, the concrete reinforcement volume comprises a reinforcing mesh. The reinforcing mesh is substantially parallel to the sloping wall. The reinforcing mesh extends through the reinforcing mesh in both the foot and the wall portion. The reinforcing mesh is folded at an end located in the wall portion towards a free end of the wall portion. The reinforcing mesh is folded at an end located in the foot towards a free end of the foot. The reinforcing mesh in the concrete reinforcement volume extends over at least 80% of the length of the concrete reinforcement volume, preferably at least 85% and more preferably at least 90%.

The reinforcing mesh is a grid of bars. The bars have a diameter of at least 6 mm, preferably at least 8 mm, more preferably at least 9 mm and even more preferably at least 10 mm.

The reinforcing mesh is advantageous for reinforcing the corner formed by the wall portion and the foot. The reinforcing mesh is suitable for absorbing moments with respect to an axis along the longitudinal direction and through the corner formed by the wall portion and the foot. This is, for example, a moment caused by the force that higher ground exerts on the wall portion of the prefab concrete element. If this moment cannot be absorbed sufficiently in the concrete, the wall portion would rotate with respect to the foot and the concrete reinforcing element would be stretched in a direction parallel to the sloping wall. Concrete does not withstand stretching well and the concrete reinforcement volume may crack and finally the prefab concrete element may break in the corner formed by the wall portion and the foot. The reinforcing mesh exerts a tensile force opposite to the stretch, thus avoiding the cracking and breaking of the concrete reinforcement volume and finally the prefab concrete element.

A prefab concrete element, wherein both legs comprise their own reinforcing mesh, C\I as described in a previous embodiment, and wherein the prefab concrete element C\I comprises a concrete reinforcement volume comprising a reinforcing mesh is advantageous for forming a retaining wall with a height of up to more than 5m, wherein the retaining wall has a low surcharge load.

LO

C\I A prefab concrete element, in which both legs comprise their own reinforcing mesh and wherein the reinforcing meshes are folded over in the corner to form a conduit, as described in a previous embodiment, and wherein the prefab concrete element comprises a concrete reinforcement volume comprising a reinforcing mesh is advantageous for forming a retaining wall with a height of up to more than 5m, wherein the retaining wall has a high surcharge load.

According to an embodiment, the wall portion is wider at the foot than at an opposite end. The opposite end is a free end of the second leg of the L-shape. This is advantageous because the lateral force of higher ground increases closer to the foot of the prefab concrete element. A wider wall portion can absorb more compressive force.

According to a further embodiment, the wall portion has an equal width from the opposite end over a distance of at least 30 cm, after which the width gradually changes to the width of the wall portion at the foot. This is advantageous because when a retaining wall is used next to, for example, a higher path, for example a pedestrian path made of clinkers, the clinkers can be placed up to the prefab concrete element, which in the case of a wall portion with a gradually changing width from the opposite end to the foot is not possible. In that case, the clinkers would abut a lower portion of the wall portion. This is particularly advantageous when placing prefab concrete elements according to the present invention side by side on a slope, where adjacent elements have different heights. The width of the wall portion at the opposite end can be the same for all prefab concrete elements, but the required width of the wall portion at the foot differs due to the different heights of the wall portion, so that in a gradual transition according to an embodiment described above, depending on the height of a prefab concrete element, a clinker can be placed closer to or further away from the wall portion. This is a hindrance for placing clinkers, especially at transitions between prefab concrete elements. Alternatively, it could be decided to take an equal width of the wall portion at the foot in case of adjacent prefab concrete elements and to have the width increase equally gradually from the foot. However, this results in a different width at the opposite end of the wall portion, C\I which again hinders the placement of clinker at transitions between the prefab C\I concrete elements. C\I

O 20 According to an embodiment, the wall portion is rounded at one end opposite the foot. The end opposite the foot is a free end of the second leg of the L-shape. The C\I rounding has a radius of at least 5 mm, preferably at least 7 mm and even more preferably at least 9 mm. A rounding with a radius of at least 5 mm is advantageous for installing a fence on top of a retaining wall. Such a fence is attached to the retaining wall by means of a U-shaped or L-shaped profile. A U-shaped or L-shaped profile is obtained by pleating a rectangular metal plate. This is always with a rounding radius. Due to the rounding of the wall portion at one end opposite the foot, the U-shaped or L-shaped profile can fit closely against the wall portion.

According to an embodiment, the foot is narrower at an end opposite the wall portion than at the wall portion. The end of the foot opposite the wall portion is a free end of the first leg of the L-shape. The transition from the length of the foot at the wall portion to the shorter length at the opposite end can be gradual or stepped. Such a foot is advantageous for forming corners in a retaining wall or for forming convex retaining walls. Convex retaining walls are retaining walls that form an arc or circle, wherein the foot of the prefab concrete elements is on the inside of the arc or circle.

According to an embodiment, the wall portion is higher on a first side than on a second opposite side. The first and second sides are opposite along the longitudinal direction. The transition in height from first side to second side is gradual. This embodiment is advantageous for forming a retaining wall along a sloping surface, where the slope is in the direction of the retaining wall.

According to an embodiment, the foot comprises projecting concrete reinforcement. The projecting concrete reinforcement comprises a single row of bars, placed side by side in the longitudinal direction of the prefab concrete element. Alternatively, the projecting concrete reinforcement comprises two or more rows of bars. A row comprises at least 4 bars per meter, preferably at least 6 bars per meter, more preferably at least 8 bars per meter and even more preferably at least 10 bars per meter. The bars have a diameter of at least 6 mm, preferably at least 8 mm, more preferably at least 9 mm and even more preferably at least 10 mm. The projecting concrete reinforcement is advantageous for integrating a prefab concrete element into a concrete floor slab.

C\I According to an embodiment, on a first side of the wall portion, the distance seen in the longitudinal direction from the wall portion to the foot is at least 10 cm more, preferably at least 15 cm more, more preferably at least 20 cm more and even more preferably at least 25 cm more than the distance from the wall portion to the foot on a second opposite side of the wall portion. Such a foot is advantageous for forming convex retaining walls.

According to an embodiment, the wall portion comprises openings or recesses. This is advantageous for the passage of, for example, pipes or the integration of lighting in a retaining wall.

In what follows, the invention is described by way of non-limiting figures illustrating the invention, and which are not intended to and should not be interpreted as limiting the scope of the invention.

DESCRIPTION OF THE DRAWINGS

The prefab concrete element has an L-shaped cross-section. A first leg is the foot (2). A second leg is the wall portion (1). The wall portion (1) and the foot (2) are substantially perpendicular to each other. The foot (2) is at least 1 cm shorter in the longitudinal direction at both ends than the wall portion (1). The wall portion (1) comprises a groove (4) in the height direction in a second side wall (12). The groove (4) runs over the full height of the prefab concrete element. The prefab concrete element comprises in a corner, formed by the foot (2) and the wall portion (1), a concrete reinforcement volume (3), which extends over the full length of the foot (2). In the wall portion (1) there is a lifting element (5), suitable as a point of engagement for lifting the prefab concrete element.

The prefab concrete element is analogous to the embodiment from Figure 1. The wall portion (1) comprises a reinforcing mesh (6). The reinforcing mesh (6) is placed C\I closer to a side wall of the wall portion (1) on the foot side (2) than to an opposite C\I side wall of the wall portion (1). The reinforcing mesh (6) comprises a folded portion (7). The folded portion (7) is folded away from the foot (2). The folded portion (7) lies in an extreme corner formed by the foot (2) and the wall portion (1). The foot (2) comprises a reinforcing mesh (8). The reinforcing mesh (8) is placed closer to a C\I side wall of the foot (2) on the wall portion side (1) than to an opposite side wall of the foot (2). The reinforcing mesh (8) comprises a folded portion (9). The folded portion (9) is folded away from the wall portion (1). The folded portion (9) lies in an extreme corner formed by the foot (2) and the wall portion (1). The folded portions (7) and (9) form a duct (10) in an extreme corner formed by the foot (2) and the wall portion (1). The concrete reinforcement volume (3) comprises a reinforcing mesh (14). The reinforcing mesh (14) is folded at one end (15) in the wall portion in the direction of a free end of the wall portion. The reinforcing mesh (14) is folded at an end (16) in the foot towards a free end of the foot.

The prefab concrete element is analogous to the embodiment from Figure 1 and Figure 2. On a first side (11) of the wall portion (1), the distance seen in the longitudinal direction from the wall portion (1) to the foot (2) is at least 10 cm more than the distance from the wall portion (1) to the foot (2) on a second opposite side (12) of the wall portion (1). The wall portion (1) comprises a tongue (13) in the height direction in a first side wall (11). The tongue (13) runs over the full height of the prefab concrete element. The wall portion (1) is wider at the foot (2) than at an opposite end (18). The wall portion (1) has from the opposite end (18) a part (17) with a height of at least 15 cm, wherein the wall portion (1) has an equal width, after which the width gradually changes to the width at the foot (2).

Claims

CLAIMS1. A prefab concrete element for constructing a retaining wall comprising a wall portion, a foot and a reinforcing mesh, wherein the prefab concrete element has an L-shaped cross-section, wherein a first leg is the foot and a second leg is the wall portion, wherein the first and second legs are substantially perpendicular to each other, and wherein the width in the direction of the first leg, the height in the direction of the second leg and the length perpendicular to the L-shaped cross-section is defined, characterized in that the foot is at least 1 cm shorter in the longitudinal direction at both ends than the wall portion.
2. The prefab concrete element according to claim 1, characterized in that the wall portion comprises a groove in the height direction in a first side wall and a tongue on a second side wall opposite in the longitudinal direction, wherein the groove and the tongue are complementary.
C\I 3. The prefab concrete element according to claim 1 or 2, characterized in that both legs comprise their own reinforcing mesh.
4. The prefab concrete element according to claim 3, characterized in that the reinforcing meshes are folded, in each leg, in the corner formed by the foot and the wall portion, over a distance of at least 10 cm in a U-shape and away from the other leg, wherein the folded portions of the reinforcing meshes form a conduit.
5. The prefab concrete element according to any of the previous claims 1-4, characterized in that the prefab concrete element comprises a concrete reinforcement volume in a corner, formed by the foot and the wall portion, wherein the concrete reinforcement volume extends over the full length of the foot and is bounded by the wall portion, the foot and a sloping wall.
6. The prefab concrete element according to claim 5, characterized in that the concrete reinforcement volume comprises a reinforcing mesh, the reinforcing mesh being substantially parallel to the sloping wall, wherein the reinforcing mesh extends through the reinforcing mesh in both the foot and the wall portion and wherein the reinforcing mesh is folded at one end in the wall portion in the direction of a free end of the wall portion and at one end in the foot in the direction of a free end of the foot.
7. The prefab concrete element according to any of the previous claims 1-6, characterized in that the wall portion is wider at the foot than at an opposite end.
8. The prefab concrete element according to claim 7, characterized in that the wall portion has an equal width from the opposite end over a distance of at least 30 cm, after which the width gradually changes to the width at the foot.
9. The prefab concrete element according to any of the previous claims 1-8, characterized in that the wall portion is rounded at an end opposite the foot, wherein the rounding has a radius of at least 5 mm.
10. The prefab concrete element according to any of the previous claims 1-9, C\J characterized in that the foot is narrower at an end opposite the wall portion C\I than at the wall portion. C\Io 20
11. The prefab concrete element according to any of the previous claims 1-10, characterized in that the wall portion is higher on a first side than on a C\I second opposite side.
12. The prefab concrete element according to any of the previous claims 1-11, characterized in that the foot comprises projecting concrete reinforcement.
13. The prefab concrete element according to any of the previous claims 1-12, characterized in that on a first side of the wall portion, the distance viewed in the longitudinal direction from the wall portion to the foot is at least 10 cm more than the distance from the wall portion up to the foot on a second opposite side of the wall portion.
14. The prefab concrete element according to any of the previous claims 1-13, characterized in that the wall portion comprises openings or recesses.