GB2154629A

GB2154629A - Yieldable stilt

Info

Publication number: GB2154629A
Application number: GB08503583A
Authority: GB
Inventors: David Robert Little
Original assignee: HOLYWELL ENG Ltd
Current assignee: HOLYWELL ENG Ltd
Priority date: 1984-02-23
Filing date: 1985-02-12
Publication date: 1985-09-11
Also published as: GB8503583D0; CA1224634A; GB8404807D0; GB2154629B

Abstract

A yieldable stilt, suitable for use with a roadway support in a mine, takes the form of a generally tubular member 10, means 16, 17 for reducing at least one cross-sectional dimension thereof and at least one longitudinal indentation 21, 22 extending over at least a major portion of the length of the generally tubular member. The generally tubular member may be of rectangular or square cross-section and may be open down one side thereof. The dimension-reducing means may then comprise means, for example one or more nuts and bolts, for narrowing the opening 11 in said side. <IMAGE>

Description

SPECIFICATION Vieldable stilt for mine roadways The invention is a novel form of yieldable stilt for use in mine roadways.

A problem in the construction of mine roadways is that varying pressure in a vertical direction arising from overlying strata need to be absorbed in the roadway supports if the integrity of the roadway is to be preserved. Stilts of various designs have therefore been devised, which are attached to the legs of roadway supports and are intended to allow progressive yielding to occur under increased vertical pressure, to avoid sudden disturbance of the strata above the roadway.

A particularly advantageous form of yieldable stilt is described in prior UK Patent No. 1247348.

The stilt described therein possesses indentations in the direction of the length of the stilt which allow progressive penetration of a roadway support into the interior of the stilt as the overlying pressure increases. A particular advantage is that the yielding in response to pressure is very uniform and highly controllable in terms of yield load.

However, the above-described prior stilt has the disadvantage that variations in roadway height at the time of installation of the stilt and associated support can only be accommodated by inserting packing between the support and the roof or floor of the roadway.

It is therefore an object of the present invention to provide a further improved stilt which gives a uniform response to increasing load but which can be modified to accommodate variations in roadway height.

The stilt according to the present invention, for use with a mine roadway support, comprises an elongated, generally tubular member, means for reducing at least one cross-sectional dimension thereof, and at least one longitudinal indentation extending over at least a major portion of the length of the generally tubular member.

In referring to a generally tubular member, it is not intended to limit the invention to a circumferentially closed tube, that is one which has an uninterrupted external surface. Rather it is intended also to include in the expression an elongated hollow member which has a longitudinal opening throughout at least a portion of its length, or an elongated member of U-section, or a similar member whose cross-section corresponds to three sides of a rectangle or square. By adopting a tubular form having a discontinuous circumference such as one of these aforedescribed types, it becomes possible to reduce the cross-sectional dimension thereof in a particularly satisfactory manner, by providing means for "squeezing" opposed faces thereof towards each other.

The roadway support, and in particular a leg feature thereof, is inserted axially into the interior of the stilt in use. Thus the shape and dimensions of the stilt are dictated by the cross-section of the support to be inserted therein. The stilt may therefore be generally circular or square in cross-section and preferably of such internal dimensions as to limit the non-axial movement of the support within the stilt. Thus the support may be a close sliding fit within the stilt.

By providing means for reducing at least one cross-sectional dimension of the stilt, it becomes possible to tighten the fit of the stilt upon the roadway support and thereby to secure the stilt to the support. In this way the overall height of the support and stilt combined may be adjusted in situ to accommodate variations in the mine roadway height, at the time of installation of the support. It is particularly preferred that the stilt be of the partially or fully split, generally tubular type referred to above as this form of stilt affords best frictional grip upon the support over the inserted length thereof while also affording maximum ease of adjustment during installation.

The means for reducing a cross-sectional dimension of the stilt may be separate from the stilt itself or integral therewith. For example, a separate device may surround the stilt and be adjustable so as to tighten the grip of the stilt upon the support.

However it is much preferred that the adjustment means should be integral with the stilt. Thus, in the case of a stilt having a longitudinal opening, generally parallel flanges may project from opposite edges of the opening or welded studs may be secured to opposite sides of the opening and such flanges or studs may be urged together by bolts or like means to reduce the width of the opening and tighten the stilt upon the support.

Whatever the cross-sectional shape of the stilt, it is also provided with at least one longitudinal indentation extending over at least a major portion of its length. Conveniently, two or more parallel such indentations may be provided, for example in opposite faces of the generally tubular stilt. The indentations may be of uniform depth throughout at least a major part of their length and may advantageously be of progressively increasing depth for a short distance at the end which is nearer to the roadway support, to form a lead-in for the support as the latter begins to overlap the indentations.

The indentation or indentations may alternatively be of progressively increasing depth over the whole of their length or a major part thereof, thereby affording a progressively increasing resistance to axial movement of the support through the stilt.

The indentation or indentations will extend over a major portion of the length of the stilt and may, indeed, extend throughout the length thereof but they may conveniently begin, with or without the aforesaid lead-in, at a sufficient distance from the end on which the roadway support is inserted to allow initial installation of the assembly without the support engaging the indentations. Thus the indentation or indentations may begin at a point remote from the means for reducing a cross-sectional dimension of the stilt and may then extend in a direction away from said means.

If desired, additional dimension-reducing means may be provided, located in the area of the indentation or indentations. Such additional means may afford extra support in that area of the stilt, either to maintain the integrity of the stilt or to provide additional control of the resistance of the stilt to loading (the "yield load" of the stilt), In operation of the stilt during mining, any initial settling of the overlying layers is accommodated by sliding of the support within the stilt against the frictional resistance of the grip of the stilt by the first-mentioned adjustment means. However further pressure of the overlying layers on the support brings the support into engagement with the indentations and affords controlled further absorption of the pressure in the assembly.By the use of additional means such as described above, the yield load of the stilt may be set either to be uniform in use or to increase as the roadway support progresses through the stilt.

The invention will now be further described with reference to the accompanying drawings, in which Figure 1 is a vertical elevation from the front of one form of stilt according to the present invention, showing a support member in position within the stilt; Figure 2 is a vertical elevation corresponding to Figure 1 but from the side of the assembly; Figure 3 is a plan view corresponding to Figure 1; Figure 4 illustrates an alternative adjustment means, in a view corresponding to that of Figure 1; Figure 5 illustrates yet a further adjustment means, in a view corresponding to that of Figures 1 and 4; Figure 6 is a plan view, similar to that of Figure 3, of a further form of stilt according to the invention; Figure 7 is a vertical elevation of yet another form of stilt according to the invention, showing a support member in position within the stilt; and Figure 8 is a plan view, similar to that of Figures 3 and 6, of yet another form of stilt according to the present invention.

Referring firstly to Figures 1 to 3, a mine support stilt 10 is in the form of an elongated generally tubular member of rectangular cross-section, having a longitudinal opening 11 in one flat face 12 thereof. The stilt 10 is welded to a base-plate 13 at bottom end, by means of which it may securely abut the ground in use. Flanges 14 and 15 project, parallel to each other, from opposite sides of the longitudinal opening 11 and, by tightening a nut 16 on a bolt 17 extending between the flanges, enable opposite faces 18 and 19 of the stilt 10 to be urged towards each other. The lower end of a roadway support member 20 of H-section is inserted, during construction of the roadway, into the upper end of the stilt 10 and therefore tightening of the nut 16 secures the stilt around the support member 20.It is therefore possible to adjust the overall length of the support member/stilt assembly to match the adjacent height of the mine roadway, when the roadway is being constructed.

In the lower portions of the faces 18 and 19 of the stilt 10 are formed indentations 21 and 22 respectively. These indentations are of uniform depth throughout a major part of their length but have their upper ends lead-in extensions 21a and 22a of gradually increasing depth. The depth of the indentations in their uniform sections is such that the roadway support member 20 cannot pass into the adjacent part of the stilt without deforming and/or cutting into these indentations.

When, in use, the pressure of the overlying strata upon the upper end of the support 20 causes the support to penetrate progressively further into the stilt 10 against the frictional resistance in the area of the bolt 17, the lower end of the support eventually encounters the indentations 21 and 22.

Further pressure is controlled by uniform deforming and/or cutting of the indentations, which ensures highly controlled "settling" of the roof of the roadway.

The alternative stilt 23 of Figure 4 is generally similar to stilt 10 but has elongated flanges 24 and 25 at its upper end, enabling the stilt 23 to be secured to the support member 20 with two bolts 26 and 27.

The further form of stilt 28 illustrated in Figure 5 has four securing flanges 29, 30, 31 and 32, enabling securing of the stilt 28 to the member 20 by bolts 33 and 34, effective over a greater length of the member 20.

In the further form of stilt 35 illustrated in Figure 6, three longitudinal indentations 36, 37 and 38 are located, respectively, in the rear face 39 of the stilt and on each side of a longitudinal opening 40 in the front face 41 of the stilt. It will be observed that the indentations in this form of the stilt are in those faces which, in plan view, are at right angles to the indented faces of the stilt 10 of Figures 1 to 3. By this re-positioning of the indentations, it becomes possible to re-orientate the stilt relative to the support member 20, to enable the bolt 17 to be orientated in a different direction with respect to the length of the mine roadway.

The form of stilt 42 shown in Figure 7, in which parts similar to those of Figure 1 are indentified by the same reference numerals, differs from stilt 10 in having a second bolt 43 and nut 44, extending between flanges 45 and 46 projecting from opposite sides of the longitudinal opening 11 at a point in the region of the indentations 21 and 22. By adjustment of the nut 44, appropriate further support may be given to the lower end of the stilt 42 and the yield load in the region of the indentations may be adjusted as desired.

Finally, the further form of stilt 47 illustrated in Figure 8 has three longitudinal indentations 48, 49 and 50, so disposed as to engage the adjacent surfaces of the roadway support 20. Whereas, in the other forms of stilt shown, the efficiency of the action of the respective indentations upon the roadway support is to a greater or lesser extent dependent upon the bolts and the resistance to lateral opening of the stilt, in the case of stilt 47 the indentations are wholly or largely self-sufficient in their action.

Claims

1. A yieldable stilt for use with a mine roadway support, comprising an elongated, generally tubular member, means for reducing at least one crosssectional dimension thereof, and at least one longitudinal indentation extending over at least a major portion of the length of said generally tubular member.

2. A yieldable stilt as claimed in claim 1, wherein said generally tubular member is longitudinally open throughout at least a portion of its length.

3. A yieldable stilt as claimed in claim 2, wherein said generally tubular member is rectangular or square in cross-section and is open throughout the length of one side thereof.

4. A yieldable stilt as claimed in any of the preceding claims, of such internal dimensions as to be a close sliding fit upon a conventional mine roadway support.

5. A yieldable stilt as claimed in any of the preceding claims, wherein the means for reducing a cross-sectional dimension thereof comprises an adjustable device, separate from the stilt and sur rounding it.

6. A yieldable stilt as claimed in any of claims 1 to 4, wherein the means for reducing a cross-sectional dimension is integral with the stilt.

7. A yieldable stilt as claimed in claim 6, having a longitudinal opening and wherein the means for reducing a cross-sectional dimension comprises means to urge together the opposite edges of the opening.

8. A yieldable stilt as claimed in claim 7, having generally parallel flanges projecting from opposite edges of the opening and bolts or like means to urge said flanges together.

9. A yieldable stilt as claimed in claim 7, having welded studs secured to opposite sides of the opening and bolts or like means to urge said studs together.

10. A yieldable stilt as claimed in any of the preceding claims, wherein said at least one indentation is of uniform depth throughout at least a major part of its length.

11. A yieldable stilt as claimed in claim 10, wherein said indentation is of progressively increasing depth at one end thereof.

12. A yieldable stilt as claimed in any of claims 1 to 9, wherein said at least one indentation is of progressively increasing depth over at least a major part of its length.

13. A yieldable stilt as claimed in any of the preceding claims, having at least two said indentations.

14. A yieldable stilt as claimed in claim 13, hav ng two said indentations in opposite faces thereof.

15. A yieldable stilt as claimed in any of the preceding claims, wherein said at least one indentation begins at a point remote from the means for reducing a cross-sectional dimension of said stilt and extends in a direction away from said means.

16. A yieldable stilt as claimed in claim 15, having additional means for reducing a cross-sectional dimension of said stilt, located in the area of said at least one indentation.

17. A yieldable stilt for use with a mine roadway support, substantially as hereinbefore described with reference to, and as illustrated in, Figures 1 to 3, or Figure 4 or Figure 5 or Figure 6 of the accompanying drawings.

18. A yieldable stilt for use with a mine roadway support, substantially as hereinbefore described with reference to, and as illustrated in, Figure 7 or Figure 8 of the accompanying drawings.