GB2395499A

GB2395499A - Placing of material in subterranean spaces

Info

Publication number: GB2395499A
Application number: GB0227421A
Authority: GB
Inventors: Patrick Forker
Original assignee: Individual
Current assignee: Individual
Priority date: 2002-11-25
Filing date: 2002-11-25
Publication date: 2004-05-26
Also published as: GB0227421D0

Abstract

A method of placing a material in a subterranean space, comprises introducing the material into the space through a downwardly-extending passage, and distributing the material laterally within the space by a distributing means beneath the passage. The distributer is a rotating member and it's rotational speed can be adjusted to control the distance the material is thrown. The distributer is controlled by air fed from the surface or there may be a motor at the bottom of the passage. Material is fed downwardly by a feed screw, the speed of which is adjustable. The distributor may have extendable blades. The method could be used to form piles.

Description

PATENTS ACT 1977

A10747GB-GMD

Title: Placing of Material in Subterranean Spaces 5 Description of Invention

This invention relates to the placing of material in subterranean spaces.

The invention has been devised in relation to the placing of material in subterranean spaces or voids such as those produced by mining operations.

There are many places where mining has left subterranean spaces in which 10 material is required to be placed. For example there are areas where extraction of stone, e.g. limestone, for building or industrial purposes, has left spaces at a relatively shallow depth beneath ground level, so that the overlying ground is unstable and prone to collapse. Usually the extraction technique has left pillars of rock supporting the roof of the mine, but now, in some cases more than one 15 hundred years after the mining has taken place, the condition of the supporting pillars has deteriorated to bring a real risk of collapse. To avoid this danger to buildings and anything else which may be on the overlying ground, it has been necessary to provide a further support for the overlying ground.

One way in which the problem of such subterranean spaces has been 20 tackled is by wholly or partially infilling them. Various materials have been proposed to be used for this purpose, including cementitious grout which being plowable can be pumped into the space if a suitable opening is created in the overlying ground. A material based on pulverised fuel ash has most commonly been used as the grouting material as the ash is available in large quantities and 25 relatively inexpensive being essentially a by-product of the burning of pulverised coal in power stations.

Examples of other materials which may be used for this purpose include crushed quarry materials, waste material from quarrying operations, crushed concrete or brick (recycled building materials), semi-dry or wet mixed concrete : A. À: À À. en: :::: Àe À:.::..

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or dry concrete, used railway ballast, and a variety of other (possibly recycled) materials, if they meet mechanical and environmental requirements.

However, although such materials are capable of flowing at least to some extent, they do not necessarily flow to the extent that a material can 5 completely infill a large space if it is simply introduced into the space at a single point therein. It simply forms a generally pyramidal mound beneath the opening through which it is introduced. For complete, or substantially complete, infilling of a large space, it may be necessary to introduce the filling material through a number of openings created in the overlying ground: clearly 10 this can make the infilling operation extremely expensive.

Accordingly it is one object of the present invention to overcome or reduce the above-described problem of requiring the provision of a large number of access points to a subterranean space into which a filling material is to be introduced. In tackling this problem, the invention may find application 15 in other fields.

According to one aspect of the invention, there is provided a method of placing a material in a subterranean space, comprising introducing the material into the space through a downwardly-extending passage, and distributing the material laterally within the space by a distributing means beneath the passage.

20 The material may be thrown outwardly from the vicinity of the bottom of the passage by the distributing means, e.g. by the operation of a rotating distributing element so that the material is thrown outwardly by centrifugal force. The method may comprise controlling the speed of rotation of such a 25 rotating distributing element, to control the distance by which the material is thrown outwardly. In the course of an infilling operation, the speed of rotation of the distributing element may be varied to achieve a satisfactory distribution of the filling material over a substantial area of the space.

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The supply of material to the distributing means through the passage may be controlled by feed means which may be a feed screw. As well as feeding the material downwardly through the passage, the use of a feed screw is advantageous because the material cannot drop in an uncontrolled manner onto 5 the distributing means but instead can only fall onto the distributing means by the distance thereof beneath the lower end of the screw. Thus the likelihood of damage to the distributing means is reduced.

According to another aspect of the invention, there is provided apparatus for placing material in a subterranean space, comprising means for introducing 10 the material into the space through a downwardly-extending passage, and a distributing means beneath the passage for distributing the material laterally within the space.

The distributing means may include a rotating distributing element operable to throw the material laterally outwardly within the space by 15 centrifugal force.

The distributing element may have a distributing surface including formations, e.g. blades, with which the material engages to ensure that it is effectively thrown outwardly of the distributing element. The speed of rotation of the distributing element preferably is variable.

20 The distributing formations of the distributing element may be able to assume a compact configuration for when the distributing element is being lowered into position through the passage, and be deployed to an operative configuration when the distributing element is rotating in use. Blades may be, or have parts which are, pivotable between their compact and operative 25 configurations, and be moved to the latter position by centrifugal force when the distributing element is rotating in use.

The distributing element may be caused to rotate by a fluid, e.g. compressed air, powered motor (e.g. turbine) arrangement, the compressed air being supplied to the distributing means through a pipe extending downwardly À.e..e À À - À À

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through the passageway. Control of the supply of compressed air may then be used to control the speed of rotation of the distributing element.

There may be means for feeding the material downwardly through the passageway to the distributing means, and such feeding means may comprise a 5 feed screw extending downwardly through the passageway. The lower end of such a feed screw may be disposed a relatively short distance above the rotating distributing element, so that material does not have far to fall from the bottom of the feed screw to the distributing element.

The compressed air to drive the distributing element may be fed down 10 the central body or stem of such a feed screw.

These and other features of the invention will now be described by way of example with reference to the accompanying drawings, of which: Figure 1 is a lateral view, partly sectioned, illustrating the invention in use; 15 Figure 2 is an enlarged side elevation, again partially sectioned, of the distributing means in accordance with the invention; Figure 3 is a side elevation, partially sectioned, of a further embodiment of distributing means in accordance with the invention; Figure 4 is a perspective view of the distributing means of Figure 3, in 20 use.

Referring firstly to Figure 1, this shows diagrammatically a subterranean space or void 10 such as an old mine working, overlaid by ground 11 with a surface layer 12. The ceiling of the space or void 10 is indicated at 13 and is shown as irregularly shaped as it may be natural rock, unsupported in the region 25 illustrated. A pile casing is shown at 14 extending downwardly through the overlying ground 11, 12 to define a passageway leading into the space 10. The casing 14 is supported at the ground by a collar 15 and is provided with a hopper 16 for receiving, from a supply 17, a material such as a cementitious grout or other flowable material such as hereinbefore mentioned which is to be Àe:: À:...

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used to infill the space 10. A relatively small length 18 of the casing 14 extends beneath the ceiling 13 ofthe space 10.

The ground 11, 12 may be drilled and the casing 14 installed therein by known techniques, for example a dual drilling system in which the ground is 5 drilled and the casing sunk in a single operation, with a grounddrilling head slightly preceding the lower end of the casing.

Within the casing 14 there is disposed a feed screw or auger having a helical flight 20 and a centre stem 21. The feed screw is rotatable by a motor 22 at its top end. At the bottom of the feed screw, spaced beneath the lower 10 end of the flight 20, there is a distributing head indicated generally at 23 in Figure 1 and shown in greater detail in Figure 2. This is rotatable, so that material which has been fed down the interior of the casing 14 by operation of the feed screw falls onto the distributing head and is thrown laterally outwardly as indicated by arrows 24 in Figure 1. Thus the material can be placed within 15 the space 10 a substantial distance away from its point of entry, and by controlling the speed of rotation of the distributing head 23 a more or less uniform distribution of the material over a substantial floor area of the space 10 may be achieved.

Referring now to Figure 2 of the drawings, this shows the bottom of the 20 centre stem 21 of the feed screw. It is hollow with an internal passage 30 through which compressed air is fed from an appropriate supply at the top of the feed screw, and fixed to it there is a lower end member 31 with lateral outlet apertures 32 for the air. The member 31 has a support collar 33 screwed to its lower end, and the collar 33 supports a thrust bearing assembly 34.

25 Carried on the thrust bearing assembly 34 is a rotary member 35 carrying turbine blades 36 in alignment with the air apertures 32, so that the flow of air over the blades 36 causes the member 35 to rotate. Member 35 has secured to it, by bolts 37, a distributing element 38 and a lower cap 39.

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Above the distributing element 38 there is secured an upwardly extending tapering shroud 39 which carries a number of circumferentially spaced formations, namely blades, at its lower end. The blades 40 are spaced slightly above the distributing element 38, and air exits from the region of the S turbine blades 36 by way of an upward passage 41 and outwardly extending openings 42 which in effect cause the air to flow across the top surface of the element 38. This assists in keeping the upper surface of the element 38 clean in use. In the course of use of the apparatus as above described in wholly or 10 partially infilling a subterranean space, the infilling material, be it a grout or something else, is supplied to the apparatus at 17 and the speed of operation of the feed screw 20, 21 controlled together with the speed of rotation of the distributing head 23 to place the material as required within the space. For example, at the start of the operation the rate of supply of the material and of IS rotation of the head may be high so that the material is projected a large distance from the vicinity of the apparatus, and then the speed reduced so that the material ends up nearer the apparatus. The operation may be monitored by closed circuit television.

Referring now to Figures 3 and 4 of the drawings, these show a further 20 embodiment of apparatus in accordance with the invention. In these figures, the lower end of the centre stem of a feed screw is indicated at SO and the helical flight thereon at 51. The stem 50 is hollow for compressed air supply, as above described. A lower end member 52 is fixed at the bottom of the stem 50 by a tapering screwed joint as indicated at 53, the stem 50 and member 52 25 have spanner slots as indicated at 50_, 52_ to enable this connection to be established and disconnected as required. At the bottom of member 52 there is connected a flange 54 which supports, by a number of circumferentially spaced bolts SS, an air operated motor 56 whose output spindle is indicated at 57. The spindle 57 is rotationally fast with a somewhat cup-shaped housing having a e eve À e e Àe.

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round bottom wall 58 and upwardly extending cylindrical wall 59. At the top of the cylindrical wall 59 there is an annular member 60 which is carried by the outer race 61 of a bearing whose inner race 62 is seated on the member 52.

Thus the housing 58, 59 is supported relative to the member 52 for rotation 5 about the vertical axis of the feed screw 50, 51 such rotation being caused by operation of the air motor 56.

Above the member 60 there is a distributing element 63 provided with three circumferentially spaced radially outwardly extending blades 64 whose configuration is most clearly seen in Figure 4 of the drawings. The distributing 10 element 63 also carries three outer blade portions 65 which are pivotably supported for movement between the positions in which they are illustrated in Figure 3 in which they lie against the outer cylindrical surface of the part 59, and the position shown in Figure 4 in which they extend radially outwardly in extension of the blades 64. The outer plate portions 65 are caused to be 15 deployed to the position in which they are shown in Figure 4 by centrifugal force when the distributing element 63 is rotating in use, and fall under gravity to their positions in which they are shown in Figure 3 when such rotation ceases. Compressed air is supplied to the air motor 56 by way of a passage 67 in 20 the member 52, in continuation of the passage within the feed screw stem 50.

At its lower end, the passage 67 extends laterally to a fitting 68 and pipe 69 which feeds the air motor 56. Exhaust air from the motor 56 passes from the interior of the housing 58, 59 through apertures 70 into an interior space at the bottom of member 52, from which space a passage 71 leads upwardly to a 25 lateral exit 72 slightly above the top surface of the distributing element 63.

Each of the outer blade portions 65 comprises an upwardly extending curved back portion 75 and, at the lower leading edge of the portion 75, a base portion 76. The portion 76 is upwardly inclined so that when the distributing element is rotating in the direction indicated by arrow 77, it aerodynamically :. '. À. À À

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creates some lift to assist the centrifugal force in deploying the blade parts 65 to their Figure 4 positions in extension of the blades 64. Thus the blades 65 are effective in the outward throwing of material which is delivered to them by the feed screw 50, 51.

5 In addition to use for filling subterranean spaces such as mine workings, it is contemplated the invention will also be useful in operations such as piling.

When creating a pile, apparatus as described above may be utilised but with a distributing head 23 which is substantially smaller in diameter than the diameter of the cylindrical hole for the pile. Operation of the distributing head ensures 10 that the concrete (or other material) of the pile is effectively packed around the periphery of the pile. The apparatus would be withdrawn as the pile is created.

In the present specification "comprises" means "includes or consists of"

and "comprising" means "including or consisting of".

The features disclosed in the foregoing description, or the following

15 claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

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Claims

1. A method of placing a material in a subterranean space, comprising introducing the material into the space through a downwardly-extending 5 passage, and distributing the material laterally within the space by a distributing means beneath the passage.

2. A method according to Claim 1 wherein the distributing means throws

the material laterally outwardly from the vicinity of the bottom of the passage.

3. A method according to Claim 2 wherein the material is thrown outwardly by a rotating distributing element, by centrifugal force.

4. A method according to Claim 3 further comprising controlling the speed 15 of rotation of the distributing element, to control the distance by which the material is thrown outwardly.

5. A method according to any one of the preceding claims further comprising controlling the supply of material to the distributing means by the 20 operation of feed means extending through the passage.

6. A method according to Claim 5 wherein the feed means is a feed screw.

7. Apparatus for placing material in a subterranean space, comprising 25 means for introducing the material into the space through a downwardly-

extending passage, and a distributing means beneath the passage for distributing the material laterally within the space.

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8. Apparatus according to Claim 7 wherein the distributing means includes a rotating distributing element operable to throw the material laterally outwardly within the space by centrifugal force.

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9. Apparatus according to Claim 8 wherein the distributing element has a distributing surface including formations which engage the material to throw it outwardly.

10. Apparatus according to Claim 9 wherein said distributing formations 10 comprise blades.

11. Apparatus according to Claim 9 or Claim 10 wherein the distributing formations are able to assume a compact configuration enabling the distributing element to be lowered into position through the passage, and to be deployed to 15 an operative position when the distributing element is rotating in use.

12. Apparatus according to Claim 11 wherein the distributing formations are, or have parts which are, pivotable between their compact and operative configurations, and are deployed by centrifugal force when the distributing 20 element rotates.

13. Apparatus according to any one of Claims 8 to 12 wherein the speed of rotation of the distributing element is variable.

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14. Apparatus according to any one of Claims 8 to 13 wherein the distributing element is caused to rotate by a compressed air powered motor.

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15. Apparatus according to any one of Claims 7 to 14 further comprising means for feeding the material downwardly through the passageway to the distributing means.

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16. Apparatus according to Claim 15 wherein said feeding means comprises a feed screw extending downwardly through the passageway.

17. Apparatus according to Claim 16 wherein the lower end of the feed screw is spaced a short distance above the distributing means.

18. Apparatus according to Claim 14 and Claim 16 wherein compressed air is fed to the distributing element down a central body of the feed screw.

19. A method or apparatus substantially as hereinbefore described with 15 reference to and/or as shown in the accompanying drawings.

20. Any novel feature or novel combination of features described herein and/or in the accompanying drawings.

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