Mine roof support

Abstract

A yielding mine roof support is provided which is made in the form of a hollow tube made from an epoxy, phenolic, or polyester fiberglass composite.

Claims

1. A yielding mine roof support, in a form of a hollow tube made from a composite selected from the group consisting of an epoxy fiberglass composite, a phenolic fiberglass composite, and polyester fiberglass composite, wherein a wall thickness of the hollow tube is between 1 mm and 15 mm, wherein a fiber orientation of the fiberglass along a length of the hollow tube is of from 1% to 49% radial orientation and wherein a balance of the fiber orientation is of a longitudinal orientation, wherein the fiber orientation is configured for balancing between hoop strength and longitudinal tensile strength, wherein the hollow tube tapers over at least a portion of the length of the hollow tube, wherein the tapered portion of the hollow tube is from 25 mm to 150 mm in length and is located at an end zone of the hollow tube, wherein a total weight of the support is from 9 kg for a 1.5 m length support to 6 kg for a 1 m length support, and wherein the yielding mine roof support is configured to support a load of a roof of a mine with a yield design point at 40 tons.

2. The yielding mine roof support of claim 1, wherein the tapered portion of the hollow tube is from 50 mm to 100 mm in length.

3. The yielding mine roof support of claim 1, wherein the tapered portion of the hollow tube has at least a third less material than an untapered portion.

4. The yielding mine roof support of claim 3, wherein the tapered portion of the hollow tube has at least 50% less material than an untapered portion.

5. The yielding mine roof support of claim 4, wherein a wall thickness of the hollow tube tapers over at least a portion of the length of the hollow tube, wherein the taper is machined post production.

6. The yielding mine roof support of claim 5, wherein the tapered portion of the wall thickness of the hollow tube is located at an end zone of the hollow tube.

7. The yielding mine roof support of claim 5, wherein the tapered portion of the hollow tube has at least a third less material than an untapered portion.

8. The yielding mine roof support of claim 7, wherein the tapered portion of the hollow tube has at least 50% less material than an untapered portion.

9. The yielding mine roof support of claim 1, wherein the tube wall thickness is proportional to a preselected load that the support is designed for, such that the tube wall thickness of a support designed for a lower load is less than the tube wall thickness of a support designed for a higher load.

10. The yielding mine roof support of claim 1, wherein the composite is epoxy resin composite, wherein the hollow tube has a nominal 100 mm inner diameter with a design load of 15 ton, and wherein the tube wall thickness is 4.2 mm.

11. The yielding mine roof support of claim 1, wherein the composite is epoxy resin composite, wherein the hollow tube has a nominal 100 mm inner diameter with a design load of 30 ton, and wherein the tube wall thickness is 8.3 mm.

12. The yielding mine roof support of claim 1, wherein the composite is epoxy resin composite, wherein the hollow tube has a nominal 100 mm inner diameter with a design load of 40 ton, and wherein the tube wall thickness is 11 mm.

13. The yielding mine roof support of claim 1, wherein the composite is epoxy resin composite, and wherein the composite further comprises a flame retardant.

14. The yielding mine roof support of claim 1, configured to avoid an initial spike and drop in load due to initial yielding.

15. The yielding mine roof support of claim 1, configured to yield initially without a sudden drop in load.

16. The yielding mine roof support of claim 1, wherein the hollow tube is seamless.

17. The yielding mine roof support of claim 1, wherein the hollow tube is a pillar structure.

Description

DESCRIPTION OF THE FIGURES

(1) The invention will now be illustrated with reference to the accompanying Figures in which:

(2) FIG. 1 shows a diagram showing the tapering of the mine roof support to ensure slow initial yielding of the unit when it reaches the design load of 40 ton;

(3) FIG. 2 shows photos before and after a yield test;

(4) FIG. 3 shows the results of a test on a support without a taper;

(5) FIG. 4 shows the result of a test on a support with a taper; and

(6) FIG. 5 shows a 40 ton support of the invention.

DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION

Experiments

(7) The design specifically allows for yielding at one end of the support by tapering the one end of the support. See FIG. 1 for a design load of 40 ton. The taper is designed to ensure that a slow yielding process initiates when the support reaches its design load. The taper is machined post production and removes half of the wall thickness over a length of 50 mm to 100 mm.

(8) The tapered design of the support allows for gradual yielding at one specific end. Please see FIGS. 3 and 4 for test results on a support (14 ton support with 4 mm wall thickness) without taper and support with taper. It is critical that a gradual load is maintained while the unit yields. FIG. 3 shows the initial drop in load unwanted from a yielding unit. FIG. 4 shows that the new tapered design of the invention removes initial drop in load.

(9) Both graphs indicate a second sudden increase and drop in load. This carbon fibre reinforcement can be included (or not) to indicate that a certain yield distance has been reached.

(10) The lessons learned on the 14 ton support tests were then implemented on a 40 ton support. See FIG. 5 for these test results. The variance of load while yielding is between 35 and 50 tons. This variance was decreased to 10 tons (varying between 40 tons and 50 tons) during subsequent tests. FIG. 5 shows the results for the new tapered design of the invention for a 40 ton support.

(11) The wall thickness of an epoxy resin composite support of the invention is shown in the Table 1 below as a function of load design.

(12) TABLE-US-00001 TABLE 1 Design load as a function of wall thickness (with a constant inside diameter of 100 mm) Design load Wall thickness (mm) 15 ton 4.2 30 ton 8.3 40 ton 11

(13) The inventor believes that the invention, as illustrated, provides a mine roof support which is an improvement over the described prior art above as the slenderness ratio of the current beam is also relatively high but the inventor has developed a fibreglass support with specific fibre orientation to prevent buckling of the support. The main aim was not to try and develop a prop to carry/support as high a possible load but to rather design an optimal support that is cost competitive and lighter weight compared to the current wood only support beams that is becoming scarcer and more difficult to source by the day.