[0002] Support packs are used in underground situations to provide extended areal support in an excavation between a footwall and an opposed hanging wall.

[0003] It is known to make support packs from a plurality of different materials including timber, cementitious blocks and a combination of timber and cementitious blocks.

[0004] Depending on a variety of factors timber packs can be cheaper to construct than cementitious packs but the characteristics of the timber packs can be less predictable than the characteristics of cementitious packs which are made from blocks manufactured in factories under controlled conditions.

[0005] Combination packs have also been constructed from timber poles or slabs arranged in vertically extending structures with intermediate relatively small concrete blocks.

[0006] Generally it can be said that cementitious-based packs reach rated loads with a relatively small degree of yield whereas timber packs initially yield fairly easily and only after a substantial degree of yield reach higher load-bearing capacities.

Consequently in designing a combination timber/cementitious-based pack a

compromise must normally be made between the curve of load versus yield for the pack and the cost of the pack components.

SUMMARY OF INVENTION [0007] The invention provides a support component which includes an elongate timber element which, in a first direction, which is transverse to a longitudinal axis of the element, has a compressive strength of a first value, and a body which is positioned adjacent the timber element and which is made from a suitable material which, in a second direction which is parallel to the first direction, has a compressive strength of a second value which, at least initially, is greater than the first value.

[0008] The timber element, in the first direction, may have a thickness t and the body, in the second direction, may have a thickness T, where T > t.

[0009] The timber element may have a length, in a third direction which is co- incident with the longitudinal axis of the element and the body, in a fourth direction which is parallel to the third direction, may have a length L, where L < t.

[0010] Preferably 0, se < L < e.

[0011] The timber in a fifth direction which is at a right angle to the third direction and which is at a right angle to the first direction may have a width w and the body, in the fifth direction, may have a width W where W > 2w. Preferably W > 3w.

[0012] The body may be made from a settable material and preferably is made from a lightweight cementitious material which optionally is foamed. This material may be

formed with formations e. g. one or more holes which promote yielding of the body in a controlled way during use.

[0013] The body of cementitious material may be reinforced in any suitable way internally or externally. Use may be made of steel wire or rods or fibres, wood splinters or the like for this purpose.

[0014] The invention further extends to a support pack which includes a plurality of bodies, each body being made from a settable material and being of parallelepiped form, stacked at least partly over one another in a vertically extending column and a plurality of elongate timber elements arranged in a cage-type structure which surrounds the column of bodies.

[0015] Each body may be made from a precast lightweight cementitious material.

[0016] The timber elements may be arranged in a plurality of alternating pairs of elements with a first pair of elements being spaced apart and parallel to each other and extending in a first direction and a second pair of elements being spaced apart and parallel to each other and extending in a second direction which is at a right angle to the first direction and crossing the first pair of elements.

[0017] The cementitious bodies between each pair of elongate timber elements may be brought into contact with each other.

[0018] In one embodiment an open volume or column is formed inside the support pack, surrounded by the cementitious bodies.

BRIEF DESCRIPTION OF THE DRAWINGS [0019] The invention is further described by way of example with reference to the accompanying drawings in which : Figure 1 is a perspective view of a support component according to one form of the invention; Figure 2 is an end view of the support component shown in Figure 1; Figure 3 is a plan view of a support pack constructed from a plurality of the support components shown in Figures 1 and 2; Figure 4 is a side view of a support pack assembled from support components in the manner shown in Figure 3; Figure 5 shows two support components of the type shown in Figures 1 and 2 being assembled to form part of a support pack; Figures 6 and 7 show another support pack at different stages of construction; and Figures 8 and 9 show a further variation, at different stages of construction.

DESCRIPTION OF PREFERRED EMBODIMENT [0020] Figures 1 and 2 of the accompanying drawings illustrate in perspective and from one end respectively a support pack component 10 according to the invention.

[0021] The component 10 includes an elongate timber element 12 and a precast lightweight cementitious body 14 which is positioned adjacent the timber element and which is secured thereto in any appropriate way, for example by means of flexible wire ties 16. The wire ties may be positioned in grooves in the body 14 and in grooves in the element 12 or extend through holes which are formed in the element.

It is also possible for the wire ties 16 to be embedded in the body 14 and for

extended ends thereof to be wrapped around the element 12 at suitable locations and twisted together so that the element is securely attached to the body. Another possibility is to bore holes in the body and the-timber element and to thread the wire ties through these holes [0022] The size of the timber element may vary according to requirement but typically the length t in a direction which is co-incident with a longitudinal axis of the timber element is from 850mm to 900mm. The timber element has a thickness t and a width w, taken in each case at a right angle to the longitudinal axis of the element, see Figure 2, with each dimension being from 60mm to 95mm.

[0023] The cementitious body 14 is made in a factory under controlled conditions and optionally has an internally foamed structure. The body has a length L in a direction which is parallel to the longitudinal axis of the timber element which may range from about 300mm to 600mm and a thickness T and a width W, see Figure 2, of about 100mm and 300mm respectively.

[0024] Figures 3 and 4 illustrate in plan and from the side respectively a support pack 40 which is constructed from a plurality of support components 10 of the kind shown in Figure 1.

[0025] Figure 3 illustrates in solid lines a first pair of components designated 10A and 10B respectively which are positioned adjacent each other with the respective timber elements 12A and 12B spaced apart, and parallel, to each other. Outer sides 42A and 42B of the bodies 14A and 14B respectively, remote from the timber elements (see Figure 1), are positioned abutting each other. A second pair of support components designated 10C and 10D respectively in Figure 3, is then placed

over the first pair. The support components are turned through 90° relatively to the underlying components 10A and 10B and are placed so that the respective cementitious bodies lie squarely on the underlying bodies 14A and 14B. The timber elements 12C and 12D are transverse to the elements 12A and 12B. This orientation and arrangement are also illustrated in the exploded view of Figure 5.

[0026] In the illustrated example the length of each cementitious body is twice its width and consequently the bodies can be stacked over each other in pairs in directions or orientations which alternate through 90° relatively to each other to form a vertically extending column 60 of cementitious bodies which is substantially square in cross section.

[0027] On the other hand the timber elements which optionally, in the vertical direction, have a thickness which is slightly less than the thickness of the cementitious bodies are positioned in a cage-like structure 62 which surrounds the cementitious column 60.

[0028] When the support is loaded the cementitious blocks in the column 60 initially take the load. The timber elements do not contact each other in any meaningful way in the vertical direction and consequently the load characteristic of the pack is determined by the cementitious blocks only. As the load increases the cementitious blocks start yielding and the height of the column of blocks decreases. Overlying portions of the timber elements are gradually brought into contact with each other at the four corners of the cementitious column 60. With further yielding the load characteristic of the support pack is determined by the characteristics of the timber elements which essentially form four load-bearing vertically extending columns 64A, 64B, 64C and 64D at the respective corners of the cementitious column 60 and by

the characteristics of the cementitious column. In addition, as the timber elements are forced together in the vertical direction they become locked to each other to an increasing extent. Thus the cage-like structure 62 which surrounds the column 60 of cementitious blocks also acts to contain the cementitious blocks, in a radial sense, to a substantial degree.

[0029] It has been found that the pack of the invention has a satisfactory curve of load versus yield. The cost of the pack, for a given load-bearing capability, is lower than the cost of a pack made only from cementitious blocks and although the cost of the pack of the invention is higher than the cost of a timber-only pack this is more than compensated for by the better load versus yield curve which is obtained.

[0030] In a variation of the invention the dimensions t and T are substantially equal, and the full area of the support pack is immediately available to take load. This may be desirable in certain conditions.

[0031] Figures 6 and 7 illustrate a modified pack 40A at different stages of construction. Three components 10G, 10H and 10J are used in each horizontal layer 68 of the pack, and the cementitious bodies 14G, 14H and 14J are formed with respective holes 70 which, in use, promote yielding of the bodies in a controlled manner. The components 10G and 10J oppose each other while the third component 10H is substantially"between"the components 10G and 10J. The following overlying layer of components is essentially a mirror image of the lower layer. Each layer is clearly of an extended area, compared to the Figure 3 pack, and has three timber elements 12 in each layer.

[0032] Figures 8 and 9 show a pack 40B which has four components 10P, 10Q, 10R and 10S per layer 68. The components are similar to those used in the pack 40A and are positioned to form a vertical hollow column 76 inside the pack, surrounded by the cementitious bodies 14 which, in turn, are enclosed by four timber elements per layer.

[0033] The area of the pack is clearly further increased by this configuration.

[0034] Other arrangements of the packs are possible in order to obtain different densities of components per layer, and various load bearing configurations and yield characteristics which depend, at least, on the amount of material used per pack.