GB2247906A - Structural elements - Google Patents

Abstract

An earth structure is provided with a plurality of rectangular facing panels (1) having moulded ridges (2) of increasing spacing and width parallel to the shorter, vertical sides (3) thereof. Some of the facing panels are secured in a first orientation and others are secured in a second orientation inverted relative to the first, to create archetectural effects. The facing panels have securing means (4, 5) for securing them to structural elements, such as counterforts, of the earth structure. The securing means (4, 5) and the vertical sides (3) of the panels are such as to permit the use of the two orientations of the panels. <IMAGE>

Description

'Structural Elements' This invention relates to facings and facing elements for earth structures such as retaining walls or embankments.

Earth retaining walls and similar earth structures may comprise relatively massive constructions, for example gravity walls, which resist overturning by virtue of their weight. However, there has been a-trend more recently to build walls with relatively thin facings and which are stabilised in other ways. Thus, foe example, United Kingdom Patent No 13 24 686 describes stabilised earth structures in which reinforcing elements are embedded in layers in an earth fill to interact frictionally with the earth, the facing comprising interlocking rigid facing elements secured to the reinforcements at the face of the structure.In United Kingdom Patent Application 22 19 025, an alternative type of structure is described in which concrete footings carry a series of counterforts extending rearwards into the earth fill and rigid facing elements are separately secured to the front of the counterforts to produce a facing.

The present invention concerns earth structures with thin facings comprising separate abutting panels mounted on rearward structural elements. The facing elements or panels are normally modular and are typically made of concrete cast in moulds either on site or in a factory. They are provided with securing means which are designed and spaced to engage with corresponding securing means on the rearward structural elements. Such securing means are relatively accurately positioned to ensure that each facing element will fit into the structure.

However, such facing systems have hitherto been relatively plain. United Kingdom Patent No 13 24 686 referred to above discloses cruciform panels which interlock to provide a facing which retains a measure of flexibility and these, in practice, provide a characteristic pattern. However, there is a demand for a wider range of architectural surfaces for such facing systems.

The present invention is based on the concept that facing elements or panels may be provided with a surface decoration which is asymmetrical about an axis of symmetry and that a striking architectural surface can be created by alternating the orientation of the panels with respect to this axis. However, it is essential for such a system to be applied to a modular facing systen that the securing means on the panels are placed symmetrically with respect to said axis of symmetry so that they engage accurately with the rearward structural elements in both orientations and that the edges of the facing elements are also symmetrical about said axis.

According to one feature of the present invention we provide facing elements for an earth structure each comprising a front face carrying a surface decoration which is positioned asymmetrically with respect to an axis of symmetry in the plane of the front face, the facing elements being provided with securing means for engaging with structural elements of the earth structure, which securing means and the abutting edges of the facing elements are positioned symmetrically with respect to said axis of symmetry whereby the facing elements can be secured to said structural elements in either of two orientations.

According to a further feature of the invention, we provide an earth structure comprising facing elements according to the invention secured to structural elements, at least some of the facing elements beingsecured in one of said orientations and at least some of the facing elements being secured in the other of said orientations.

In general, it is possible for the decoration on the facing elements also to be asymmetrical about at least one further axis of symmetry and for the securing means and abutting edges also to be symmetrically positioned with respect to such further axes, so that the facing elements could be mounted in additional orientations, thereby increasing the number of options available to the architect.

However, it is preferred for simplicity that there are only two possible orientations of the facing elements.

The securing means will be of various types according to the nature of the structural elements to which they must be secured. For systems with counterforts, as described in greater detail below, the facing elements may carry studs or bolts which protrude rearwards and engage in holes in the structural elements. Alternatively, and more preferably, holes may be provided in the facing elements and engage with bolts protruding from the front of the counterforts, nuts attached to said bolts serving to secure the facing elements and optionally being covered by caps or other protective means. The holes may thus be concealed by such caps, which will typically present a concrete-like outer surface, or they or the caps may form part of the asymmetrical decoration.

An alternative method of securing the facing elements to counterforts is the provision of hooks on the rear of the facing elements which simply hang on appropriate engagement means such as brackets on the counterforts. Conversely the, facing elements may have rearward brackets which engage with hooks on the counterforts. In order to ensure the rigidity of the system, such securing means preferably include means which prevent or limit relative lateral movement between the facing elements and the counterforts.

In general, rectangular facing elements will be mounted with the long sides horizontal, although other orientations may be used.

For attachment to the embedded reinforcing elements of a stabilised earth structure, the facing elements may conveniently have rearwardly extending flat tabs provided with holes adapted to be bolted to the reinforcing elements which are typically metal strips, for example according United Kingdom Patents No 15 63 317 or 21 71 140.

The facing elements are preferably relatively-thin panels. Rectangular panels are preferred. The edges of the facing elements may simply abut or they may be provided with a more complex profile; however, it is essential that the facing elements engage accurately with each other independently of their orientation about the said axis of symmetry.

For heavy panels the securing means may be provided in vertically separated pairs. In general, several securing means will be provided for each facing element.

These will be spaced and positioned to engage with the structural elements and permit accurate abutment of the facing elements in either of the orientations. In practice at least two alternative spacings of the engaging means on the supporting structure may be used and the facing elements may be provided with sets of securing means appropriate for more than one support configuration. Thus, in a preferred embodiment, each facing element is provided with first and second sets of securing means, the first set of securing means comprising securing portions at a first spacing from each other, and the second set of securing means comprising securing portions at a second spacing from each other, whereby the structural elements to which the facing elements are to be secured can be at either said first spacing or said second spacing.

The asymmetrical surface decoration will preferably consist of a profile or texture which can be cast into the surface using an appropriately profiled mould.

Particularly striking effects can be obtained by patterns of ridges of different widths and/or spacings which provide trapped shadows. One particularly preferred surface decoration on rectangular panels comprises ridges arranged parallel to the axis of symmetry, which is typically vertical, the spacing between the ridges increasing or decreasing with distance from one of the lateral edges; when two such panels are positioned side by side in opposite orientations, the grooves between the ridges produce an optical effect creating the illusion of a convex or concave surface.

Counterfort structures are particularly preferred.

Viewed from a preferred aspect the invention provides a structure having a footing and prefabricated concrete elements which comprise a series of parallel counterforts carrying facing elements according to the invention which are attached to the counterforts in each of at least two possible orientations.

With such an arrangement prefabricated facing elements according to the invention can be relatively quickly and accurately attached to the counterfort on site. In general, assembly on site takes less space than casting on site of monolithic counterfort wall units with integral facing since no moulds or shuttering are required on site and since the individual elements are all normally flat, transport is greatly facilitated as compared with monolithic counterfort wall units.

The panels may be attached with the counterfort in the final, vertical position of use, but in practice the counterfort will normally be arranged horizontally during attachment of the panels. If any panels are then damaged when the whole unit is lifted by a crane or otherwise to the vertical position, the individual damaged panels can be replaced as necessary, rather than discarding the whole unit.

The panels will normally be prefabricated away from the site and are preferably protected from knocks during storage and transport by suitable packaging. The structure will normally comprise a plurality of counterforts in a row and these counterforts may also be prefabricated and packaged for protection in the same way.

A typical panel may be rectangular e.g. 2.0 m by 1.0 m and their abutting edges may be separated by a strip of water seal material. The abutting edges may conveniently be keyed to provide an interlocking surface which may help to reduce water seepage.

Certain embodiments of the invention will now be described by way of example and with reference to the accompanying drawings in which: Fig. 1 shows a perspective view of a facing element according to the invention; Fig. 2 shows a side elevation, partly in section, of a structure comprising a counterfort wall having a plurality of panels joined to a counterfort; Fig. 3 shows in front elevation, a counterfort wall assembled from panels as shown in Fig. 1.

In the facing element shown in Fig. 1, a concrete panel 1 is provided with moulded ridges 2 of increasing spacing and width parallel to the shorter sides 3 thereof. Holes 4 are provided in vertically space pairs for engagement with bolts on two supporting counterforts. Holes 5 are also provided for engagement with bolts on three supporting counterforts, thus allowing the panels to be used at two different cou-nter-fort spacings. The holes 4 and 5 may include sleevescSast into the concrete and means, not shown, for enqagement- with flush covering caps which effectively camof1aqe- the points of'attachment.

For attachment-- to re-inforcing- elements in a stabilised earth structure, the holes 4 and 5-may be replaced by tabs of the type described in United Kingdom Patent No. 13 24 686, said studs being provided with holes for bolting to reinforcing elements.

Referring to Fig. 2, the counterfort wall, 6 comprises a counterfort 7 to which a plurality of facing panels are attached by bolts through the holes 4 (not shown) and a footing 8 for supporting the wall. The footing rests on a distribution plate 9 which is also engaged by the lowermost facing panel 1. An erection bolt 10 extends between the distribution plate and the counter fort 7 and is arranged so that during construction a nut on the bolt is raised or lowered to adjust the orientation of the unit consisting of the counterfort and panels. Once the correct adjustment is made the footing 8 is cast and embeds reinforcing bars (not shown) protruding from the bottom of the counterfort. The rear face of the counterfort includes a bend 11 which provides savings in the amount of concrete used.

In the counterfort wall shown in Fig. 3, ridges 2 in the panels 1 cooperate to create the optical illusion of a series of vertical columns or bays.

Claims (10)

1. Facing elements for an earth structure each comprising a front face carrying a surface decoration which is positioned asymmetrically with respect to an axis of symmetry in the plane of the front face, the facing elements being provided with securing means for engaging with structural elements of the earth structure, which securing means and the abutting edges of the facing elements are positioned symmetrically with respect to said axis of symmetry whereby the facing elements can be secured to said structural elements in either of two orientations.

2. Facing elements as claimed in claim 1, wherein each facing element is provided with first and second sets of securing means, the first set of securing means comprising securing portions at a first spacing from each other, and the second set of securing means comprising securing portions at a second spacing from each other, whereby the structural elements to which the facing elements are to be secured can be at either said first spacing or said second spacing.

3. Facing elements as claimed in claim 1 or 2, wherein the facing elements are rectangular panels and the axis of symmetry is vertical, and wherein the surface decoration comprises ridges arranged parallel to the vertical axis of symmetry, the spacing between the ridges increasing or decreasing with distance from one of the lateral edges.

4. An earth structure comprising facing elements as claimed in claim- 1-, 2 or 3, the facing elements being secured to said structural elements, at least some of the facing elements being secured in one not saidorientations and at least some of the facing elements being secured in the other of said orientations.

5. An earth structure as claimed in claim 4, wherein the structural elements are counterforts.

6. An earth structure as claimed in claim 5, wherein holes are provided in the facing elements and engage with bolts protruding from the front of the counterforts, nuts attached to said bolts serving to secure the facing elements.

7. An earth structure as claimed in claim 4, wherein the structural elements are reinforcing elements embedded in the earth of a stabilised earth structure.

8. An earth structure as claimed in claim 7, wherein the facing elements have rearwardly extending flat tabs provided with holes adapted to be bolted to the reinforcing elements.

9. Facing elements substantially as hereinbefore described with reference to the accompanying drawings.

10. An earth structure substantially as hereinbefore described with reference to the accompanying drawings.