EARTH STRUCTURES

Abstract: A facing element (2), for use in a stabilised earth structure (1), comprises a reinforcing portion (60) extending substantially across the facing element, the reinforcing portion having at an end thereof a connection point for connection to an earth stabilising member (4) and/or an adjacent facing element.

Description: Earth structures This invention relates to facing elements for earth structures, such as stabilised earth structures, and to earth structures having a facing made up of such facing elements. It also relates to earth stabilising members for earth structures. It is frequently necessary to provide earth structures, such as embankments, in civil engineering projects. Such structures comprise a mass of earth which must be securely retained, typically with at least one steep facing. One method of mechanically stabilising the earth is to use the so-called tie and anchor technique in which strong facing elements hold back a mass of earth, the facing elements being held in place by means of ties or the like which pass through the mass of earth to dead-man anchors. An alternative technique is to stabilise the earth by means of a plurality of frictional stabilising elements extending rearwardly from a facing of the structure into the earth mass. In these structures, the earth is stabilised throughout the mass by frictional engagement with the stabilising elements, which may for example be in the form of strips, sheets or grids. Commonly, the facing of the structure consists of facing elements in the form of concrete panels which are connected to the forward ends of the frictional stabilising elements. A variety of arrangements of such a system are known from GB-A- 1 324 686. It is known from GB-A-1 324 686, to provide a facing formed from a number of like concrete panels connected to stabilising strips. In some of the systems described, lugs are cast into the panels to form connection points for stabilising strips. Although these systems have been highly successful, they do suffer from certain drawbacks. In particular, the concrete panels have to be comparatively thick in order to have sufficient strength to provide a secure connection to the stabilising strip and to allow forces to be transmitted between the panels and the strip. The thickness of the panels results in comparatively high material and transport costs, and also increases the difficulty of handling the panels on site. It was also proposed in GB-A-1 324 686 to connect the earth stabilising strips to pins located in vertical holes in the edges of the concrete facing panels. However, this system was never put in to commercial production, possibly because it was considered that even thicker panels would have been required to cope with the concentration of loads caused by providing the panel to strip connections at the edges of the panels. According to a first aspect of the invention there is provided a facing element for use in a stabilised earth structure, the facing element having a reinforcing portion extending substantially across the facing element, the reinforcing portion having at or adjacent an end thereof a connection point for connection to an earth stabilising member and/or an adjacent facing element . The invention also extends to an earth structure formed using a plurality of such facing elements and to a method of constructing such an earth structure. As the reinforcing portion extends substantially across the element, it significantly strengthens the element and is able to transfer forces effectively between the element and an earth stabilising member and/or an adjacent element. As a result, the remainder of the element can be made thinner, and therefore lighter, than is the case with conventional elements. Consequently, the overall weight of the element may be significantly reduced, leading to lower material, transport, handling and erection costs. If the connection point is used for connecting the element to an earth stabilising member, the design of the facing element can be simplified compared to conventional facing elements in which the connection point is provided inset from the edge of the element. The reinforcing portion may be arranged to extend laterally across the facing element, but preferably it extends upwardly/downwardly, i.e. vertically when the facing element forms part of a vertical facing, or at a rearwardly tilted angle to the vertical when the facing element is itself rearwardly tilted in a battered facing. The reinforcing portion may be positioned inset from an edge of the element; for example two reinforcing portions may be provided which are inset from respective opposite edges of the element. Alternatively, the reinforcing portion may be provided at an edge of the element; for example two reinforcing portions may be provided at respective opposite edges of the element. In one preferred embodiment a reinforcing portion is provided at each edge of the element. Thus, a plurality of reinforcing portions may together extend about substantially the entire periphery of the facing element. The reinforcing portion can be formed in a number of ways, for example, it can be formed integrally with the remainder of the element. Thus, if the element is formed of cast concrete, as is conventional, a rib or other reinforcing profile could be cast as part of the element. The connection point for the stabilising member and/or adjacent facing element can then be formed at one end of the reinforcing profile, eg. by casting a connecting pin or lug to project from the profile or providing a hole in the profile into which a connecting pin or lug (which may be a separate pin or lug or may be formed on a stabilising member or adjacent element) can be inserted. In the example mentioned above of plural reinforcing portions extending about the periphery of the facing element, these may be provided by a thickened peripherally extending flange which surrounds a thinner central portion. The resultant facing element then has a shallow open box shape. Connection points can then be provided in the flange at the corners of the element. As an alternative to integral formation of the reinforcing portion with the rest of the facing element, the reinforcing portion can be provided by means of a member which may be formed of a different material from that of the remainder of the element. This may be attached to the outside of the element for example in the form of an external brace, but, at least in the case of cast concrete elements, it is preferred to locate it at least partly within the facing element. This may be achieved by casting the reinforcing portion in place. A further possibility provided by the present invention is that the stiffening effect of the reinforcing portion allows the use of plates or sheets e.g. of metal such as steel to form the facing elements. Such elements may be much thinner than those made of concrete. Again, there are various ways in which the reinforcing portion may be formed, including casting or rolling it integrally with the facing. However, it will often be desirable to form metal facings from lengths of sheet metal. The reinforcing portion may then, if desired, be formed by bending the metal, eg by using a press. This is most conveniently done near the edges of the panel. Although the bent portions may be formed at, say, the vertical edges only, it is preferred to bend all of the edges in by about 90 degrees. Preferably each bend is a similar distance from the respective edge of the panel to form a peripherally extending rim, so that the resultant facing element has a shallow open box shape. When an arrangement having such a bent portion is used, it will generally be desirable to provide the connection point in the form of a discrete member or assembly which is attached to the reinforcing portion. In the preferred shallow-box construction, the connection point is located at a corner where the structure is strongest. If a number of assemblies is to be provided, they may each be located at a corner. Although suitable assemblies may be bolted into place, it is preferred that they be welded. A typical construction will comprise two pin-like connectors at the upper corners and two pin-receiving connectors (eg. holes or tubes) at the lower corners. An alternative construction has a reinforcing portion in the form of a separate (typically elongate) reinforcing member. This may then be secured to the facing by any conventional method, such as by bolts, rivets, adhesives or welding. Welding is, however, preferred since a connection can thereby be formed along most of the length of the reinforcing member, either continuously or at intervals eg. by spot-welding. For aesthetic reasons, when the reinforcing portion is exposed it will normally be provided on the rear of the facing element. However, this is not essential, and in certain designs it may be preferable to make the reinforcing portion visible by locating it on the front. The connecting point may be provided by a bracket or other connecting device cast into or otherwise secured to the reinforcing portion. Preferably, however, the connection point is provided by a connecting pin. It is then a simple matter during construction to locate a connector such as a hole, loop or hook formed in the end of an earth stabilising member around the connecting pin. Additionally, or alternatively, an adjacent panel may be attached by engaging the pin with a corresponding part of that panel. In certain preferred embodiments, the connecting pin is connected to the rear of the facing element and there is preferably a clearance between the rear of the element and the pin. This construction is particularly useful when a sheet facing is employed. One way to achieve this construction is by forming the pin with a crank or by mounting it on a bracket. The clearance enables a stabilising member to be connected to the element without the requirement for a large gap between vertically adjacent elements to accommodate it. Although such a cranked pin may be connected to the rear of a cast facing element, if it is desired to use such a pin, a preferred construction is partially to cast the pin into the facing element. Thus, the pin may comprise three parts: a first part cast into the facing; a second part projecting outwardly from the rear of the facing to provide an offset; and a third part providing the connection point. In most constructions, the third part will be generally parallel to the first, and hence to the rear face the of facing panel. Although in the simplest facing element only a single connecting pin is necessary, if only this pin is used to connect earth stabilising member(s) to the facing element, then the element must be employed carefully to ensure that there is no resultant couple about the pin resulting from its connection to a stabilising member which could destabilise the structure. It is therefore preferred that a plurality of pins (eg. two) be provided and that each of these is connected to a stabilising member. The connecting pin may be provided separately of the facing element, for example to be received in a hole formed at one end of a reinforcing portion. Alternatively, however, the connecting pin may be permanently fixed to the facing element. The facing element will normally be constructed to cooperate with other facing elements to form the facing of an earth structure. It is highly advantageous if the connecting pin mentioned above is used to provide both the connection point to an earth stabilising member, and to provide connection to another facing element provided with suitable pin receiving means, such as a hole, recess, collar, loop or hook. The facing element therefore preferably comprises receiving means for receiving a connecting pin of an adjacent like element. This dual use of the connecting pin ensures simplicity of design. The connecting arrangement of the pin in the receiving means is most appropriate for connecting vertically adjacent facing elements. During construction, it enables the element to be held in position by an element or elements below before an earth stabilising member has been attached to the upper element and anchored by having earth placed thereon. Where the facing element is assembled with like elements to form a planar eg. vertical facing, then the connecting pin and receiving means will normally both be parallel to the plane of the facing. It may however be desired to have vertically adjacent facing elements at different angles, for example a lower element arranged vertically and an upper element tilted rearwardly. The connecting pin and receiving means arrangement may be used to accommodate such a change in angle, for example by arranging the connecting pin and/or the receiving means of the facing element at an angle (i.e. non- parallel) to the main plane of the facing element. The facing element may have a lower edge designed to rest on the upper edge(s) of an element or elements below, for example with a deformable strip located between the edges. The pin and receiving means arrangement then assists with location and support of the element during construction, but will not normally transmit significant loads between adjacent elements. In certain preferred embodiments, however, the receiving means is arranged to provide an abutment against which the connecting pin of the adjacent like element may abut at least during construction. This is very useful since, although in a completed stabilised earth structure the weight of the facing elements is generally supported by their frictional engagement with the earth behind them (against which they are held by the earth stabilising members) , such support is not available during the construction process. Thus, since the facing element has a receiving means with an abutment against which a connecting pin of another element can abut, forces can be transmitted from one element to the next by means of the pin and receiving means rather than via the edges of the elements. Therefore, the edges of the elements do not have to be designed and constructed to withstand bearing against adjacent elements during construction. They can be spaced apart. In the case of a connection between vertically adjacent elements, the weight of an element or elements above causes the connecting pin to be loaded in axial compression. A further advantage is that in a completed structure there is less likelihood that relative movement of adjacent elements will result in damage to the elements. Moreover since the edges of the panels need not directly inter-engage, there is much greater freedom in the choice of element shapes, and, apart from the connecting pins and receiving means, the elements can be made to greater tolerances. A further advantage is that no interlocking formations such as tongues, grooves or lips are required along the edges. Thus, the edges may be straight from front to back, as viewed in a typical cross-section, although the edge profile may differ locally in the vicinity of a connecting pin or receiving means. It will be appreciated from the foregoing that various advantages stem from the arrangement in which the receiving means provides an abutment against which the connecting pin of an adjacent like element may abut eg. during construction. It is believed that this development is, in itself, inventive, and thus, from a second aspect the invention provides a facing element for use with other like elements in an earth structure, the element having a connecting pin for engaging with a first adjacent like element and receiving means for receiving the connecting pin of a second adjacent like element, the receiving means having an abutment against which the connecting pin of the second adjacent like element may abut. As mentioned previously, this enables forces to be transmitted between adjacent facing elements via the connecting pin and receiving means rather than via the edges of the element. This simplifies construction and avoids damage to adjacent elements. Such a facing element need not necessarily have the reinforcing portion and earth stabilising member connecting point described in relation to the first aspect of the invention, although these features are preferred. The other features mentioned herein concerning the connecting pin and the receiving means may also be incorporated in preferred embodiments of the second aspect of the invention. The connecting pin and receiving means arrangement for connecting facing elements may be designed such that the pin abuts against a rigid member and such an arrangement will be suitable for use in low cost applications or where a comparatively short design life is appropriate. However, preferably, the receiving means or the connecting pin comprises a deformable member, such as a block or pad of elastomeric material, for example rubber, plastics, cork or the like. The purpose of such a deformable member is to accommodate at least a degree of relative movement between the facing elements making up a facing of a structure as a result of settlement of the earth of the structure and also to provide a degree of tolerance in the fitting of the elements. The deformable member may be provided separately of the facing element for assembly therewith during construction, or it may be adhered to the facing element ready for assembly. If the reinforcing portion extends substantially across the facing element, in accordance with the first aspect of the invention, it is ideally suited to accommodate forces arising from the element's interconnection to other elements, as well as those which occur as a result of the connection to the stabilising member. In particularly preferred embodiments, therefore, the connecting pin is provided at one end of the reinforcing portion and the receiving means is provided at the other end thereof. As previously discussed, the reinforcing portion strengthens the facing element and therefore assists in resisting the forces placed on the facing element, eg. due to the earth mass bearing against its rear face. It will be appreciated that this construction allows much more flexibility in the design of the parts of the facing panel which are visible in use. This makes much more attractive the use of non-conventional materials such as steel, plastics or composites for some or all of the facing part of the element, allows for greater freedom in the choice of element shapes for aesthetic reasons and can also lead to savings in material and fabrication costs. The connecting pin and receiving means may be separate members at opposite edges of the facing element, preferably linked for load transmission by the reinforcing portion, as mentioned above. Preferably, however, the connecting pin and the receiving means of the facing element are directly interconnected to define an elongate member. They may thus conveniently be formed integrally so that in combination they form the reinforcing portion, or a major part of it. One preferred way in which to form such a directly interconnected connecting pin and receiving means (the "elongate member") is to provide an elongate pin having a pin receiving means such as a hole formed in, or a tube or collar provided around, one end thereof. This provides a simple structure which enables forces to be transmitted from the pin and associated pin receiving means directly to the reinforcing portion and thereby to the remainder of the panel. During construction, this arrangement allows the weight of one panel to be transmitted directly through the reinforcing portions of the lower panels. A facing assembled from the facing elements may have each element in direct alignment with the one below, in which case the lateral position of the connecting pin can be chosen to suit the desired position of the earth stabilising member. Indeed, such an arrangement will normally be used where connection points are formed at the corners of the facing elements. This arrangement allows curved facings to be provided easily. However, it may be preferred that the facing be provided with a brickwork type effect by offsetting each facing element by half an element's width from the elements below. To achieve this, it is convenient to provide a pair of connecting pins each approximately of the element's width in from each side. This spacing results in a regular spacing of pins in the complete structure and therefore, if stabilising members are attached to the pins or receiving means, then these too will be evenly spaced, thereby evenly distributing forces within the earth mass. However, if as is preferred the elongate member defined by the connecting pin and the receiving means forms the reinforcing portion, such a spacing does not provide the optimum positioning for the reinforcement or stiffening of the facing element. Each reinforcing portion is preferably inset from the side of the facing element by less than 1/4 of the element's width, the preferred inset being 1/5 of the element's width. Advantageously, therefore, the elongate member is cranked such that a central portion thereof is inset from a side of the facing element by more than the spacing of the connecting pin and receiving means from the side. This arrangement will tend to be desirable for larger facing elements, but will often not be necessary for smaller ones where deflections are less. Although the invention is applicable to facing elements having a wide range of sizes, they are preferably relatively small, for example square panels 0.5m by 0.5m or 0.85m by 0.85m, or rectangular panels 0.6m in height by 0.9m wide, or 0.6m by 1.2m, or 0.5m by 0.7m, or 0.5m by 1.0m. Such small dimensions can combine with the small thicknesses which are achievable to give low weight facing elements which are easy to manoeuvre during construction. Preferred concrete facing elements may have a thickness less than or equal to 100mm, more preferably less than or equal to 80mm or even 50mm or less. Facing elements of other materials may be substantially thinner. Small scale lifting equipment can be used and this saves costs. In addition, with smaller elements the height thereof can conveniently be equal to the vertical spacing between earth stabilising members, in contrast to larger elements which often require two vertically spaced attachment points at the rear. Various types of earth stabilising member may be used with the facing element, for example the metal strips known from GB-A-1 324 686 or GB-A-1 563 317, the polymeric strips or metal "ladder" strips known from WO 94/23136, or the metal grids also known from WO 94/23136. If the connection point of the facing element is used for connection to a stabilising member and is provided by a connecting pin, then the connection of a strip or grid to the facing element may be in accordance with the teachings of the above-mentioned documents. In one preferred arrangement, there is provided a metal bar which passes round the connecting pin of the facing element and is connected, eg. welded directly to a stabilising member in the form of a metal strip. This is a particularly economical way of connecting the facing element to an earth stabilising metal strip. The metal bar may loop round a single connecting pin, or it may loop round two or more connecting pins, either belonging to the same facing element or to adjacent facing elements. By looping the metal bar round more than one connecting pin, this advantageously distributes the loading of the stabilising member to spaced locations on the facing. In a preferred construction, a recess is formed in the element at least at the connection point. The front end of an earth stabilising member may then be received in the recess and e.g. secured to a connecting pin. This allows the edges of vertically adjacent facing elements to abut or be closely spaced without fouling the stabilising member or being visible between the panels. In the shallow box construction referred to above a similar result may be obtained by in-setting the rim at least in the region of the connecting pin. The provision of a recess is particularly useful when the same pin is used to form a connection to an earth stabilising member and to an adjacent facing element. Such a recess is thus advantageous with both metal and concrete facing elements. In order to secure horizontally adjacent elements together, an earth stabilising member may be connected to two adjacent elements. Alternatively, or additionally, separate connectors may be used which are interconnected with adjacent elements' connection points. These may take the form of a plate having two holes to receive connecting pins. This construction is advantageous because it ensures correct lateral spacing of the facing elements. A predetermined degree of tolerance can be allowed for by forming the holes slightly over-size. If desired, a third hole or other connection means may be provided for co-operation with an earth stabilising member. Preferably, the facing element has a recess in an upper or lower edge thereof, the recess extending to a side of the facing element . This allows the front end of an earth stabilising member or a separate connector to locate in the recesses of laterally adjacent facing elements and interconnect their connection points. The correct lateral spacing of facing elements can be determined by the front end of an earth stabilising member, by forming the member with two laterally spaced points for attachment to the facing and a portion extending laterally between those points. Such an earth stabilising member is considered to be inventive in its own right, since it can be used with a variety of facing elements and not just those disclosed herein. Viewed from a third aspect the invention provides an earth stabilising member for use in a stabilised earth structure, comprising a pair of laterally spaced attachment points for attachment to respective portions of a facing of the structure, and a portion extending laterally between the attachment points to define the lateral space therebetween. With such an arrangement, the earth stabilising member can advantageously be used to define the correct relative position of adjacent facing elements. By providing the lateral portion between the attachment points, which in use is preferably in the same general plane as the facing, the lateral spacing of the facing elements can be maintained fairly precisely. The lateral portion may be provided separately of the rest of the earth stabilising member and assembled therewith during installation of the facing or alternatively may be a fixed or integral part of the rest of the earth stabilising member. Preferably, the attachment points are openings, which may be in the form of holes in a plate portion of the stabilising member, or in the form of loops. In the latter case there may be two loops in a continuous bar, thereby avoiding the need for a weld at an end of the bar. Alternatively two bar portions may be bent round to form respective loops, the ends of the bar portions being fixed together, e.g. by welding. As mentioned above, it is desirable to provide a deformable member between adjacent facing elements, to cope with relative movement of the elements caused by earth settlement. In a preferred arrangement, the front end of an earth stabilising member provides the deformability. Such an earth stabilising member is considered to be inventive in its own right, since it can be used with a variety of facing elements and not just those disclosed herein. Viewed from a fourth aspect the invention provides an earth stabilising member for use in a stabilised earth structure, provided with a deformable front end so that in use it can form a deformable abutment between vertically adjacent facing elements of the structure. The deformability may be provided by a block or pad of deformable material, for example rubber, plastics cork or the like, which may be provided separately of the rest of the earth stabilising member and assembled therewith during installation of the facing elements or alternatively may be fixed to the rest of the stabilising member in advance, e.g. by adhesive. It is then not necessary to provide a separate deformable member elsewhere on the edges of the facing elements. If the facing elements are connected to each other by a pin, then an annular deformable pad can locate round the pin. In one preferred arrangement, the deformability may be provided by an arrangement in which the front end of the earth stabilising member is bent to form a spring. Thus no additional material is required to provide deformability. The spring may take various shapes, e.g. a flattened "C"-shape in side elevation. If however the front end is in the form of at least one loop, then this can provide both a spring and an opening through the loop for receiving a suitable portion of a facing, such as a pin. Such an opening is preferably arranged vertically, to receive e.g. a vertical pin. The loop can effectively form a coil of the spring. Overlying portions of the member forming the loop will be spaced apart in an unstressed condition, to allow for compressive deformation. A single loop may be provided, but preferably the earth stabilising member has a pair of loops and a portion extending laterally therebetween. The advantage of this is discussed above in relation to the third aspect of the invention. Certain embodiments of the invention will now be described, by way of example only, and with reference to the accompanying drawings, in which: - Figure 1 is an elevation of an earth structure according to the invention; Figure 2 is a sectional view through an earth structure incorporating a first embodiment of facing elements; Figure 3 is a view corresponding to a portion of Figure 2 showing the connection between two adjacent facing elements,- Figure 4 is a sectional view of one of the facing elements of Figure 3; Figure 5 is a rear elevation of the facing elements of Figure 3 ; Figure 6 is a plan view of the facing element of Figure 3; Figure 7 is a schematic perspective view of a facing element of Figure 3; Figure 8 is a view corresponding to Figure 4 of a modified version of the first embodiment; Figure 9A is a partial perspective view of the stabilising member of Figure 3; Figure 9B is a partial perspective view of another form of stabilising member; Figure 10 is a plan view showing the stabilising member connected to a facing element; Figure 11 is a rear elevation of a second embodiment of facing element; Figure 12 is a perspective view of a third embodiment of facing element; Figure 13 is an end elevation of part of an earth structure incorporating facing elements of the type illustrated in Figure 12 showing the interconnection between two adjacent elements; Figure 14 is a front elevation of an earth structure incorporating facing elements of the type illustrated in Figure 12 ; Figure 15 is a partial perspective view of a facing element of the type illustrated in Figure 12; Figure 16 is a rear elevation of a fourth embodiment of facing element; Figure 17 is a plan view of the facing element of Figure 16; Figure 18 is a side end elevation, partly in section, showing the connection between two vertically adjacent facing elements according to the fourth embodiment; Figures 19A to 19G are schematic front elevations of a series of earth structures incorporating different types of facing elements according to the invention; Figure 20A is a schematic plan view of an earth structure incorporating facing elements according to the invention to form a curved facing; Figure 20B is a schematic elevation of an earth structure incorporating facing elements according to the invention to form a facing having a dog-tooth effect; Figure 21a is a schematic perspective view of the foundation for an earth structure; Figure 21b-21f are a series of schematic sectional views illustrating the construction of an earth structure incorporating facing elements according to the invention; Figure 22 is a vertical cross-sectional view showing the connection between two non-parallel facing elements; and Figure 23 is a vertical cross-section of a fifth embodiment of facing element; Figure 24 is a rear elevation of a sixth embodiment of facing element; Figure 25 is a schematic view of a front elevation of a facing structure using a number of facing elements as shown in Figure 24; Figure 26 is a partial perspective rear view of the sixth embodiment of facing element; Figure 27 is a connecting pin assembly for use in the sixth embodiment; Figure 28 is a connecting tube assembly for use in the sixth embodiment,- Figure 29 is a schematic perspective view showing the interconnection of panels of the sixth embodiment and an earth reinforcing member; Figure 30 is a rear perspective view of a seventh embodiment of facing element; Figure 31 is a side elevation, partly in section, of the connection between two vertically adjacent facing elements of the seventh embodiment,- Figure 32 is a horizontal cross-section of the connection of Figure 31; Figure 33 is a plan view of a sheet for forming the seventh embodiment of facing element, before bending; Figure 34 is a rear elevation view of an eighth embodiment of facing element; Figure 35 is a vertical section on the lines A-A of Figure 34 ; Figure 36 is a horizontal section on the lines B-B of Figure 34; Figure 37 is a vertical cross-section through the connection between two vertically adjacent elements of the eighth embodiment; Figure 38 is a perspective view of the front end of an earth stabilising element; Figure 39 is a perspective view of an alternative form of earth stabilising member,- and Figure 40 is a perspective view of a further alternative form of earth stabilising member, together with a corner of a facing element to which it is to connect. Turning first to Figure 1 an earth structure 1 is illustrated having a facing made from a plurality of discrete facing elements 2 in the form of panels. As may be seen from Figure 2, a number of rows of these elements is used to provide a facing behind which is retained an earth mass 3. The earth mass is stabilised by means of stabilising members 4 which extend rearwardly from the facing elements 2 into the earth mass. At the bottom of the facing a series of concrete foundation blocks 5 are set into the ground. Each facing element 2 is of generally rectangular shape having a width of lm, a height of 0.5m and a thickness of approximately 75mm. The elements are cast to form a single piece of concrete. Each element has a pair of elongate members 60 cast into it. The elongate members 60 comprise steel pins 6 which project at their upper end from the top of the element and extend over substantially the full height of the element. A steel tube 7 having a diameter slightly larger than the outside diameter of the pin is welded around the lower end of the pin such that the tube projects beyond the bar and slightly (at 7') from the lower face of the element (see Fig. 4) . As may be seen from Figure 3, this provides an opening 8 into which the projecting portion 6' of the pin of an adjacent element may be inserted as shown. The upper end of the projecting portion 6' of the pin is also chamfered to ease assembly. As may be seen, the pin 6 and tube 7 serve to interconnect the vertically adjacent elements. A deformable block 9 of rubber is wedged in the tube adjacent to the lower end 6" of the pin 6. In use this is sandwiched between the ends 6', 6" of the pins of adjacent elements. In order to accommodate a degree of relative movement between adjacent elements 2, the upper 10 and lower 11 edges of the elements are spaced apart by a gap 13 and this, together with the block 9 which provides a degree of play within the opening 8, allow settlement of the structure to be accommodated. The edges 10 and 11 are chamfered such that the gap 13 is wedge shaped in cross-section, being larger at the front than at the rear. An insert 14 in the form of a geotextile strip or the like is attached at the rear of the adjacent facing elements 2 to cover the gap 13 and to prevent escape of earth. The stabilising members 4 are connected to the facing by receiving through a hole, loop or hook thereof the projecting portions 6' of pins 6 at the upper edge of the facing elements 2. In order to provide clearance between the strip 4 and the adjacent elements, a recess 12 is formed in the upper edge 10 of the element 2 around the portion 6' of the pin. This recess is shown is plan view in Figure 6. As well as providing interengagement between adjacent elements and between the element and the stabilising strips, the pins 6 also serve to reinforce the element 2. As may be seen from Figure 7, the pins are each set in from their respective ends of the strip by approximately M of the element's width and so they each provide a significant strengthening effect to substantially half of the facing element 2. The force of the earth mass 3 against the back of the facing is transmitted through the concrete to the pins 6 which are themselves secured by the stabilising members 4, and in this way the forces are transmitted to the strips. A modified version of this facing 2 ' is shown in Figure 8, where like reference numerals identify components corresponding to those shown in the previous figures. In this version of the facing, it will be noted that the steel pin 6 is cranked so that each end 6', 6" is rearwardly offset. Thus, although the major part of the pin is embedded in the concrete facing, its ends do not project from the top and bottom edges of the casting. This avoids the need to form a recess to accommodate a stabilising strip 4. Instead, the strip is located around the projecting part of pin 6, behind the casting 2 ' . Figure 9A shows further details of the stabilising member 4. It comprises a steel bar 4a (e.g. an 8mm diameter bar of the type normally used to reinforce concrete) bent into a loop which engages over the projecting portion 6 ' of a pin 6. The two end portions of the bar 4a are secured to a conventional galvanised steel strip 4b, preferably by welding. An alternative form of stabilising member 4 is shown in Figure 9B. In this case a similar steel bar 4c is bent into a triangular shape to form a loop round two adjacent projecting portions 6' of pins 6, either belonging to the same facing element (as shown in Figure 10), or belonging to adjacent elements. Again the rear ends of the bar 4c are secured to a steel strip 4b. It will be noted that the facing element 2 shown in Figure 10 is modified to include a recess 12a capable of receiving the laterally extending portion of the triangular bar 4c. In the second embodiment of facing element 2 shown in Figure 11, the elongate members 60 are modified to have a central portion 61 offset from the upper and lower ends of the elongate member towards the sides of the facing element . This improves the reinforcing or stiffening function of the elongate members 60 whilst enabling the projecting portion 6' and tube 7 of each elongate member to be spaced from the sides of the facing element by M of the width thereof . Figure 12 illustrates a third embodiment of facing element 20 which can be used in place of the element of Figure 3 in the earth structure of Figure 1. The element 20 consists of a substantially planar, rectangular steel sheet 21 having the same height and width as the previously described element. However, since steel is significantly stronger than concrete, a thickness of only 5mm is required. Two elongate members 60 are welded to the rear face of the element. The pin structures comprise steel bars having upper and lower offset portions 22 ' which are formed by bending the bar and which cause the upper and lower extremities of the pin structure to be displaced from the steel sheet 21. The upper end 23 of the elongate member 60 corresponds to portion 6' of the pin of the previous embodiment and, like the pin of the modified version of that embodiment, it does not project beyond the top of the steel sheet 21. Likewise, the lower end 24 has a tube 30 welded thereto which corresponds to tube 7 of the previous embodiment. This tube 30 is arranged to project beyond the bottom of the steel sheet 21. As may be seen from Figure 13, the steel tube and the upper end 23 of the pin cooperate to form a connection in the manner previously described. A resilient block 25 is again provided within the tube. The upper end 23 of the elongate member 60 also serves as an anchorage for a stabilising member 4, although since the elongate member 60 is provided on the back of the steel sheet, no recess is necessary in the upper edge of the element in order to accommodate the stabilising member 4. Instead, as may be seen from Figure 13 , the member 4 simply passes around the upper end 23 of the elongate member where it lies beneath the tube 30 of the adjacent element and is spaced from the rear of the steel sheet. A block 26 which extends between the elongate member 60 and the steel sheet keeps the member 4 at the correct height relative to the steel sheet 21. The steel sheet 21 is significantly thinner than the concrete element 2 of the previous embodiment . No chamfering of the sheet is required at the edges, although it may be provided if desired for aesthetic or other reasons. This embodiment is used to form a frictionally stabilised earth structure as previously described. The steel bar again has the function of strengthening the facing element 20 and in this respect, it will be noted that the bar is welded to the steel sheet 21 along the entire length where they are in contact. This may be seen most clearly from Figure 15. Alternatively, spot welding may be sufficient. The steel facing element 20 shown in Figures 16-18 is similar to that of Figures 12-15, except that the elongate members 60 are modified to have a central portion 61 offset from the upper and lower ends of the elongate member towards the sides of the facing element. This offset is similar to that provided in the concrete facing element of Figure 11 and is provided for the same reasons. In this instance, the offset portion 22' is thus offset both rearwardly and laterally. This embodiment also includes a pair of upper and lower lateral bars 62 which extend between the elongate members 60 and are used to secure the elongate members to the back of the steel sheet 21. Figure 23 schematically illustrates a modified steel panel 21' where a rearwardly projecting flange 90 is provided around the edge. This serves to stiffen the panel and prevents adjacent panels from over-riding each other in the event of panel movement due to settlement. If it is desired to provide a flange which projects rearwardly further than the ends 22 ' , 24 of the pin, then cut-out portions may be provided in the flange to accommodate the ends of the pins and allow panel and strip interconnections. A particular advantage of steel panels is that they may be readily produced in a wide variety of shapes and sizes to the back of which standard elongate members 60 may be welded. As may be seen from the series of schematic elevations shown in Figures 19a to 19g, this enables a variety of attractive facings to be produced. In particular, it is possible by means of the present invention to provide facing elements which do not have top and bottom surfaces which are suitable to form a bearing surface for adjacent elements. For example, the structure of Figure 19c would be particularly difficult to construct if the facing elements of one row had to be supported by those elements directly beneath them during construction. As may be seen from Figure 20A, facing elements according to the invention may be used to construct an earth structure having a curved facing 40. This figure illustrates the use of concrete panels 2, but the steel panels 20 may also be used. The facing has a brickwork effect when viewed in elevation (as already described) so the elements 2 ' of a given layer are each disposed centrally above the edges of a pair of adjoining elements 2" in the layer below. As the pins are inset by one quarter of the width of the panel on each side, each pin 6 is axially aligned with the pins of vertically adjacent elements. It will be seen that the pins effectively form a series of axes around which the facing elements are displaced relative to each other. Figure 20B illustrates a further variation whereby a dog-tooth effect is produced. As in Figure 20A, the panels are arranged to provide a brickwork effect with the pins of vertically adjacent panels interconnected in the same way. However, in this example, the panels are provided at an angle to the plane of the facing, with alternate panels angled in opposite direction to form the dog-tooth effect. Figures 21a to 21f illustrate a method of constructing an earth structure using the facing elements of the invention. Here, the steel facing elements of the second embodiment are used but the method is equally applicable to the first embodiment. Initially, as shown in Fig. 21a, a series of foundation blocks 50 is cast in place. The blocks are spaced apart by half the width of a facing element 20 and have short steel pins 51 set vertically therein. The purpose of the short pins is to mate with the tubes 30 of the bottom row of facing elements. In order to ensure that the final structure is level it is necessary either for the upper surfaces of each of the blocks 50 to be level and for the pins 51 to be too short to axially abut against the lower panels, or for the pins to be long enough to do so, in which case their upper ends must be level. In the latter case, some variation in the level of the blocks 50 is permissible. Next, stabilising strips 4 are connected to the short pins, extending rearwardly from them (Fig. 21b) and then a first layer of earth backfill 52 is provided as shown. It will be noted that the front surface 53 of the earth is clear of the facing area. Subsequently, as shown in Fig. 21d, a first row of facing elements 20 is located on the pins 51 which prevent them from falling over. A further set of stabilising strips 4 may then be connected to the upper ends 23 of the elongate members 60 of the elements 20 and positioned on the earth backfill 52. Then, starting from the rear of the structure, more backfill is added over the stabilising strips. In this way the backfill serves to secure the facing elements 20 in position via the stabilising strips before it presses against them. As may be seen from Fig. 21f the backfill again stops short of the facing. Next, a further row of facing elements 20 is connected to the first row and the steps first described are repeated. As the weight of the panels is supported by the pins of the panels below this avoids the risk of damage to the edges of the panels, or the need to provide bearing surfaces on the edges of the panels. Further layers may be added as required. Figure 22 illustrates how vertically adjacent facing elements may be provided at an angle to each other, by forming the pin 6 with an upwardly projection portion 6' which is tilted to the rear. This arrangement, achievable by virtue of the special connecting pin and receiving means, enables elaborate facing shapes to be created. The sixth embodiment of facing panel 90 is illustrated in Figures 24 to 28. It is formed of 4mm thick plain steel sheet and is suitable for structures of up to 6m in height. Thinner metal may be used for low structures or thick metal for higher structures. The panel 90 is has its edges bent portions 91 which are bent backwards at 90° to the central part which is a 0.6m square. The bent portions extend rearwardly by about 30mm. Connecting pins 92 are provided at the upper corners and connecting tubes 93 are provided at the lower corners. In use panels 90 are connected together to form a facing as shown in Figure 25, with the connecting pins 92 of each facing panel 90 being received in the connecting tubes 93 of the panel above. It will be noted that, unlike the other embodiments, the vertical edges of the panels are aligned, rather than being offset to form a brickwork effect. The construction of panel 90, which is effectively a shallow open box, can be seen from Figure 26. The bent portions 91 stiffen the panel so that it can withstand earth pressures without other reinforcement. At each corner a section of the folded back edge 91 is cut-away to receive connecting pin assemblies 95 and connecting tube assemblies 96. Figure 27 shows a connecting pin assembly 95. It comprises a strip of steel 98 similar to that forming the remainder of the facing panel which has a bore through which the connecting pin is located. Initially these components are tack-welded together. The strip is bent so that in the finished panel a recess 97 is provided around the connecting pin to receive the end of an earth stabilising member. This prevents the stabilising member fouling the panel above or being visible through the gap between adjacent panels. The connecting tube assembly 96 (Figure 28) is formed from a steel plate 99, which is also of similar thickness to the facing panel. A tube 100 is welded to the lower face of the plate. As may be seen from Figure 26, the assemblies are located in the respective corners of the facing element so that the connecting pin 92 is directly above the tube 93. The assemblies are first tack welded into place and then the entire facing element is welded together. It will be noted that the lower end of the connecting pin is bent towards the vertical bend-line of the facing element (which it abuts) and is welded thereto. The tube assembly 96 is welded to the front of the panel and the tube itself is located within a hole 102 in the base edge 91' of the panel. The location of the pins 92 and the tubes 93 in the corners of the panels, where there are three mutually perpendicular components provided by the main panel body and the rim forming components (i.e. the bent portions 91 and the strips 98) , creates a very strong connection point. In a facing structure, the connecting pins 92 and connecting tubes 93 of vertically adjacent panels are inter-engaged in the manner described above in relation to the other embodiments. Thus, a rubber pad will generally be located within tubes 93 to accommodate settlement. However, the interconnection of horizontally adjacent panels is significantly different. As shown in Figure 29, a metal plate 105 having two holes 106 formed therein is located over adjacent connecting pins 92, thereby connecting them together. The plate 105 is located in recess 97 referred to above and keeps the elements the correct distance apart. The holes in the plate are larger than pins 92 by a pre¬ determined amount (5mm in this case) in order to accommodate a given amount of expansion and/or settlement of the structure. An earth reinforcing member in the form of an 8mm diameter steel wire 110 is then passed around the pins 92. A further layer of panels may then be added with their connecting tubes 93 engaging with the pins 92, as with previous embodiments. Since the vertical edges of the panels are aligned, rather than being offset to form a brickwork effect, it is easier to form a curved facing structure than is possible with the other embodiments. The result will also often be more attractive since, with the connection points being at the edges of the panels, they provide good pivot points. The seventh embodiment of facing panel 90 is shown in Figs. 30 to 33. It is formed of 3mm plain steel sheet and has overall dimensions of 0.6m by 0.6m. The panel has a shallow open box shape having at its edge bent portions 91 bent backwards at 90° to a main central portion 130. The bent portions extend rearwardly by about 60mm. As shown in Fig. 33 the vertically extending bent portions each have one bend line 111. The horizontally extending bent portions each have three bend lines 112, such that when the sheet is bent a horizontally extending lip 113 is formed with a horizontally extending ledge 114 behind the lip 113 and vertically inset therefrom. A horizontally extending recess 97 is thus defined behind vertically adjacent lips (see Fig. 31) for receiving the front end of an earth stabilising member. As shown in Fig. 30 the adjoining end edges of the bent portions 91 are welded at 115. A connecting pin assembly 95 is provided at each upper corner of the facing panel 90 for connection with a hole 116 provided in the lower ledge 114 at the lower corners of a panel above. A connecting pin 92 is welded at its lower end into the vertically extending bend 111 between the central portion 130 and a vertically extending bent portion 91. The pin 92 projects vertically through a hole 117 in the upper ledge 114. The eighth embodiment of facing panel is shown in Figs. 34 to 37. It is formed of cast concrete and has a main central portion 130 surrounded by a thickened flange 131. The flange 131 extends about the periphery of the panel and effectively provides four reinforcing portions extending across the panel, two vertically and two horizontally. The panel is formed along its upper and lower edges with respective horizontally extending lips 113 and ledges 114. As with the embodiment of Figs. 30 to 33 the ledges 114 are vertically inset from the lips so as to define a horizontally extending recess 97 behind vertically adjacent lips 113 (see Fig. 37) for receiving the front end of an earth stabilising member. A chamfer 135 can optionally be provided at the front edge of the flange 131, about the entire periphery of the panel, as seen in Fig. 37. Adjacent the corners of the panel, vertical blind bores are formed by casting plastic tubes 100 into the flange 131. During assembly loose connecting pins 92 are inserted in the tubes 100 to locate one panel above another. A vertical gap 140 is allowed between the top of the pin and the upper end of the tube 100 of an upper panel, to allow some play for relative vertical movement of the panels. In this example, the gap is 5mm. The example of facing panel shown in Figs. 34 to 37 is 0.5m square, with a maximum flange 131 thickness of 100mm and a central portion 130 thickness of 40mm. Other dimensions are of course possible, but this example serves to illustrate the thinness of the central portion, and thus savings in weight, compared to known panels. The front end of an earth stabilising member 120 is shown in Figs. 31, 32, 37 and 38. The front end is formed from a continuous bar into two loops 121 joined by a lateral bar portion 122. The bar extends rearwardly as two parallel elongate portions 123 interconnected at longitudinal intervals by cross- members 124. Each loop 121 engages round a connecting pin 92 in the recess 97 between vertically adjacent facing panels 90. The lateral spacing of the loops 121 is determined and maintained by the length of the lateral bar portion 122, so that the front end of the earth stabilising member can usefully define the lateral spacing between laterally adjacent panels. Each loop 121 is formed with a vertical space 125 between the lateral bar portion 122 and the rearwardly extending portion 123, so that the loop effectively forms a one coil spring able to compress or expand if there is relative movement of vertically adjacent facing panels caused for example by earth settlement. Thus, for example the lips 113 may initially be spaced apart by 5mm and the ledges 114 behind by 20mm. The earth stabilising member may be formed from 8mm diameter bar with a vertical space 125 of 4mm at the loop. The front end of another stabilising member 120 is shown in Figure 39. This differs from the earth stabilising member of Figs. 31, 32, 37 and 38 in that the lateral bar portion 122 is formed by welding together two bar end portions. As before the lateral bar portion is vertically spaced from the rearwardly extending portions 123, so as to form a deformable spring. The front end of a further stabilising member is shown in Figure 40. In this case the rearwardly extending portion 123 of the member is in the form of a flat ribbed strip, as known from GB-A-1 563 317. The front end of the strip is welded to a laterally extending plate 122 formed with laterally spaced holes 121. A facing panel 90 has an upwardly projecting connecting pin 92 on which one of the holes 121 engages to attach the earth stabilising member to the facing element. An annular deformable pad 140 is engaged on the pin, so as to provide the earth stabilising member with a deformable front end. The pad 140 could alternatively be adhered to the earth stabilising member in advance of assembly. In a modification of the Fig. 40 arrangement, the rearwardly extending portion 123 could be in the form of a tie-bar secured at its rear end to an anchor buried in the earth behind the facing.

Claims: Claims 1. A facing element for use in a stabilised earth structure, the facing element having a reinforcing portion extending substantially across the facing element, the reinforcing portion having at or adjacent an end thereof a connection point for connection to an earth stabilising member and/or an adjacent facing element . 2. A facing element as claimed in claim 1, wherein the connection point is provided by a connecting pin. 3. A facing element as claimed in claim 2, comprising receiving means for receiving a connecting pin of an adjacent like facing element. 4. A facing element as claimed in claim 3, wherein the receiving means is arranged to provide an abutment against which the connecting pin of the adjacent like element may abut. 5. A facing element as claimed in claim 2, 3 or 4, wherein the connecting pin is permanently fixed to the facing element . 6. A facing element as claimed in claim 5, comprising a metal sheet having the connecting pin fixed thereto. 7. A facing element as claimed in claim 2, 3 or 4, wherein the connecting pin is provided separately of the facing element. 8. A facing element as claimed in any preceding claim, wherein the reinforcing portion has been formed by bending part of the facing element. 9. A facing element as claimed in any preceding claim, comprising a plurality of reinforcing portions which together extend about substantially the entire periphery of the facing element . 10. A facing element aε claimed in any preceding claim, comprising a recess in an upper or lower edge of the facing element, the recess extending to a side of the facing element . 11. A facing element for use with other like elements in an earth structure, the element having a connecting pin for engaging with a first adjacent like element and receiving means for receiving the connecting pin of a second adjacent like element, the receiving means having an abutment against which the connecting pin of the second adjacent like element may abut. 12. An earth structure having a facing comprising facing elements as claimed in any preceding claim, and earth stabilising members connected to the facing elements. 13. An earth stabilising member for use in a stabilised earth structure, comprising a pair of laterally spaced attachment points for attachment to respective portions of a facing of the structure, and a portion extending laterally between the attachment points to define the lateral space therebetween. 14. An earth stabilising member as claimed in claim 13, wherein the attachment points are openings formed by two loops in a continuous bar. 15. An earth stabilising member for use in a stabilised earth structure, provided with a deformable front end so that in use it can form a deformable abutment between vertically adjacent facing elements of the structure. 16. An earth stabilising member as claimed in claim 15, wherein the front end is bent to form a spring. 17. An earth stabilising member as claimed in claim 16, wherein the front end is in the form of at least one loop. 18. An earth stabilising member as claimed in claim 17, comprising a pair of loops and a portion extending laterally therebetween. 19. An earth structure having a facing comprising facing elements as claimed in any of claims 1 to 11, and earth stabilising members as claimed in any of claims 13 to 18 connected to the facing elements.

Inventors: JAILLOUX JEAN-MARC, VIDAL HENRI CHARLES, JAILLOUX, JEAN-MARC, VIDAL, HENRI, CHARLES
Applicants: JAILLOUX JEAN MARC, PIESOLD ALEXANDER JAMES, VIDAL HENRI BREVETS, VIDAL HENRI C, JAILLOUX, JEAN-MARC, PIESOLD, ALEXANDER, JAMES, SOCIETE CIVILE DES BREVETS HENRI VIDAL, VIDAL, HENRI, CHARLES
Application year: 1996
Main classification: E02D29
IPC codes: E02D29