COMPOSITE SUPPORT PROP

A support pack component which comprises a rectangular cementitious block with metal plates on three of its edges.

BACKGROUND OF THE INVENTION

This invention relates to a pack of a kind used in an underground excavation e.g. in a mine to provide support between a hanging and foot wall and to a component for use in the construction of the pack.

In one type of support pack, of the kind referred to, use is made of a plurality of support components, each of which comprises a cementitious block of rectangular outline which is bounded on one or more edges by a timber slab. The timber slabs act to keep a plurality of the cementitious blocks, which are positioned in overlying layers, each layer including a number of the blocks, in a desired configuration or shape. The timber slabs also possess a degree of yielding load-bearing capability.

The modular type of construction which is possible using support components of this type has contributed to the widespread use of such components.

However the timber slabs are obtrusive and heavy, materially increase the weight of each component and present logistical problems during transport and handling of the blocks. Another factor which must warrant consideration is that the timber slabs are flammable and can constitute a fire hazard in an underground installation.

An object of the present invention is to provide a support component which, at least in some embodiments, addresses some of the aforementioned drawbacks.

SUMMARY OF THE INVENTION

The invention provides a support component for use in a composite support pack which comprises a cementitious block of parallelepiped form with six faces and a respective metallic plate on at least two of the faces.

The block may include two major faces and four minor faces, wherein each minor face has a surface area which is smaller than the surface area of each major face, and a respective metallic plate may be on at least two of the minor faces.

Preferably a respective metallic plate is on three of the minor faces.

Each major face may be of rectangular outline with two opposing long edges and two opposing short edges, and one metallic plate may be on a minor face which is at a long edge and respective metallic plates may be on minor faces at the opposing short edges.

Alternatively the major faces are square, and the minor faces have the same lengths.

The block may be made from an appropriate cementitious composition.

Each metallic plate may be steel. The thickness of the steel plate may be variable but typically is of the order of two to three millimetres. The metallic plate may be in the form of an elongate strip of material of a suitable length.

Due to the positioning of the steel plates on the cementitious block the steel plates/straps may cover three of the minor faces and may then be configured in a U-form. Conveniently an elongate steel strip is bent into a U-form sized and positioned to cover a minor face on a long edge of the cementitious block and to cover opposing minor faces on respective short edges of the block.

Optionally the steel strip shaped in a U, or as a square or rectangular frame, positioned on a suitable bed, can be used as at least a part of a mould when the cementitious block is cast. The steel strip may include formations or members which are configured to adhere to or to become embedded in the cementitious block, when it sets, thereby to ensure a firm bond between the steel plates and the block.

The invention also then extends to a method of making a support component for a support pack which includes the steps of forming a square or rectangular frame from an elongate metallic strip, and casting a settable cementitious material into the frame, which acts as a mould and which remains engaged with the cementitious material once it has set.

The invention further extends to a support pack which is made from a number of support components, each support component being of the aforementioned kind. The support components are positioned in a plurality of successive layers which vertically overlie one another, wherein each layer includes at least two, but preferably three or four, of the support components.

Each layer may be constructed so that metallic plates form a boundary for the blocks in the layer.

If each layer has four support components a gap may be formed amongst minor faces of the blocks which are devoid of metallic plates.

DESCRIPTION OF PREFERRED EMBODIMENT

FIG. 1 of the accompanying drawings is a perspective view of a support pack component 10 according to one form of the invention.

The component 10 comprises a block 12 which is made from a suitable cementitious composition and a steel strip 14 which forms metallic plates 16, 18 and 20 respectively.

The block 12 is of parallelepiped form and has six faces. The block is rectangular in outline. It therefore has two major faces 24 and 26. The major face 24 is uppermost and shown in FIG. 1. The face 26 is lowermost and not visible in FIG. 1.

Due to the rectangular outline of the block there are two long edges 30 and 32 which oppose each other and which are adjacent respective long minor faces and two short edges 34 and 36 which oppose each other and which are adjacent respective short minor faces. The metallic plates 16 and 20 cover the short minor faces at the short edges 34 and 36. The steel plate 18 covers the long minor face at the longer edge 32.

The metallic plates can be provided separately (individually) or can be provided by forming an elongate steel strip into a U-shape as shown for the steel strip 14. Typically the metallic plates (strip 14) have a thickness of two to 3 millimetres. This is exemplary only and non-limiting. Normally, using standardised dimensions, the block has a length L which is of the order of 600 mm and a width W which is of the order of 300 mm-these values are exemplary and non-limiting. Under these conditions the block has a thickness (height) H which is of the order of 100 mm.

An integral U-shape is preferred for the resulting component (cement block plus plate) is stronger, in respect of burst resistance, than a cementitious block which has three individual (i.e. not directly connected) metallic plates. Another benefit is that the steel strip 14 in a U-form can be used as part of a mould when the cementitious block 12 is cast. The steel strip can be provided with formations or members which project “inwardly” so that these formations or members grip the block when the cementitious composition sets. These formations can be in the form of projections which are stamped from a strip-see for example FIG. 5 which depicts a length of the steel strip 14A which is stamped, at regular intervals under factory conditions to form projecting spikes 38 which are embedded in a cementitious block 12 (not shown) when it is cast, thereby to ensure a strong bond between the components. It is possible though to use any other suitable technique to ensure the steel strip is firmly fixed to the cementitious block.

The component 10 is intended to be used as a direct replacement of a composite cement/timber support component.

FIG. 2 illustrates in perspective a single layer 40 in a composite cement pack of rectangular configuration formed from abutting side-by-side components 10A and 10B which abut at respective ends a third component 10C. The components 10A, 10B and 10C are for all practical purposes identical to one another and are the same as what has been described in connection with FIG. 1. Successive layers (not shown) each including three of the components are positioned one over the other, as is known in the art, to form a composite support pack.

FIG. 4 illustrates a layer 42 which in plan is of square configuration and which is formed from four components 10A, 10B, 10C and 10D which are identical to each other and to the component 10 shown in FIG. 1. In this instance due to the dimensions of the components a gap or hollow 46 is formed in a centre of the components—this can accommodate an elongate support prop 50 e.g. of timber, or of a different type, as is known in the art—see the plan view of the layer 42 in FIG. 4. This hollow is bounded by portions of the cementitious blocks, and is devoid of steel plates.

The support component of the invention comprises a cementitious block, preferably of rectangular outline, with metal strips or plates on at least three of the minor faces of the block. It is possible to have a metallic plate on each of the four minor faces of the block but this depends on the particular application and the expected strength of a composite pack which is formed from a plurality of the blocks. The use of four plates does however increase the cost of the support component. Nonetheless if four steel plates are used the plate can be integrally formed by bending an elongate steel strip into a rectangular shape which is closed e.g. by welding, by the use of rivets, or the like so that in use the strip forms a continuous rectangular metallic boundary around the cementitious block and in this way the burst strength of the component, under compressive loading, is significantly increased.

The principles which have been described can be used with equal effect in the making of a support component which is of a square (not rectangular) configuration.

The support component of the invention does away with the timber slabs referred to and thus eliminates a fire hazard which is associated with the use of timber. As the metallic plates are fairly thin in thickness a typical component according to the invention is lighter than a corresponding cement/timber component as referred to hereinbefore. The component of the invention is compact and does not have any protruding portions which can present logistical problems during transport and installation.