Mine Roof Support Member and Method for Constructing Improved Mine Roof Support Columns

Abstract

A support member (100) and method for constructing an improved mine roof support column (200), the support member (100) comprising a pair of bearing members (10) held in spaced apart relationship by a beam (20), each bearing member further comprising a female coupling structure (40) formed on a side opposing a complementary male coupling structure (30). A first set (300) of support members is placed in parallel, spaced apart relationship on a mine floor, and a second set (300′) of support members is turned 90 degrees relative to the first set (300) and then are coupled to the first set via the coupling structures (30 40), the process being repeated until a stacked support column (200) spanning the floor to the roof of the mine is created.

Description

CROSS REFERENCE To RELATED APPLICATIONS

Reference is made to and priority claimed from U.S. provisional application Ser. No.61/726,746 filed on Nov. 15, 2012.

TECHNICAL FIELD

The present invention pertains to the field of secondary support for subterranean mine tunnel roofs. More particularly, the present invention pertains to support members and systems used to help support mine roofs and prevent collapse of the roofs into the excavated tunnel.

BACKGROUND OF THE INVENTION

Mining operations typically involve excavating tunnels with rectangular or square shaped cross sections, with a roof portion perpendicular to the ribs. Ribs are the supporting side walls of the excavation. The roof of the tunnel must support the weight of all the strata across the open tunnel span.

Since the earliest days of mining, cribs, rectangular blocks traditionally made of hardwood, have been used as secondary support for the roofs of mines. Crib is a term of art in the mining industry, and refers to both the individual blocks stacked to form a support column and the finished support column itself, and is derived from an old Wales mining term meaning to lay at right angles to each other as in a foundation, which describes the traditional construction method for forming a support column. The traditional use of hardwood cribs was inspired by the waste products of the sawmill industry, where discarded centers of logs sawn into planks were plentiful, cheap, and uniform in size and shape.

Unfortunately, traditional cribs have many significant drawbacks. Hardwood cribs are susceptible to rot and insect attack, and while uniform in shape and size, no two cribs have the same strength characteristics because they come from different trees grown in variable conditions. The cribs are subject to swelling and shrinkage, depending on the humidity inside the tunnel. The lack of uniformity in the strength and the varying rot/insect resistance of each crib result in unpredictable strengths and unknown longevities of any given support column. Given the way in which the support columns are constructed, a rotted or otherwise strength compromised crib can only be replaced by unstacking and rebuilding the support column, a time consuming and potentially dangerous activity. Usually, the mine atmosphere dries the water from the wooden cribs, shrinking them, and breaking the support connection with the roof.

Installation of a support column made of cribs is usually a tedious and labor-intensive process, as a standard eight foot high roof requires anywhere from 20-25 stacked cribs, and the cribs must be carried in by hand and stacked manually to form the support columns. Also, as the cribs are simply dry-stacked on top of one another, any lateral movement of the roof tends to dislodge the uppermost cribs, causing the entire support column to fail and potentially resulting in a roof collapse and death or injury to individuals working inside the mine. Another problem with the traditional hardwood crib support column is that its construction results in both visual and airflow obstructions resulting in increased pressure requirements to circulate the air. As with any wood product, the support columns are highly combustible, another potential danger inside a subterranean tunnel.

More recently, with demand for hardwood high, the price of hardwood has been increasing, and the availability of hardwood for crib material has been decreasing, further eroding the attractiveness of the traditional crib.

What is needed is a crib that is lightweight and easy to install, requires no special tools or training for installation, and when installed, provides superior strength and reliability in mining applications.

DISCLOSURE OF INVENTION

The invention is an improved crib or support member, a method for constructing a support column system using the improved support member, and a support column resulting from the method using the improved support member, the support member comprising a beam having two opposed ends, each end affixed to one of a pair of bearing members held in spaced apart relation by the beam, each bearing member having a top surface and a bottom surface, the top surface further formed with a male coupling structure and the bottom surface further formed with a female coupling structure adapted to receiving the male coupling structure. The support column system is comprised of stacked sets of support members, in a typical embodiment each set comprising a pair of support members, the first set of support members laid with the bottom surface adjacent to the floor of the tunnel, the support members in parallel spaced apart relationship to one another. A second set of support members is placed on top of the first set, but with the beams of the second set turned 90 degrees in relation to the first set, and with the female couple structures of the second set receiving the male coupling structures of the first set to lock the two sets of support members together to form a column with a square lateral cross section and a hollow interior space. Additional sets of support members are stacked in this fashion until the top set contacts the roof of the tunnel, thus providing secondary support to the roof.

BRIEF DESCRIPTION OF THE DRAWINGS

The features and advantages of the invention will become apparent from a consideration of the subsequent detailed description presented in connection with accompanying drawings, in which:

FIG. 1 is a perspective view of the improved crib or support member according to the invention.

FIG. 2 is a bottom elevational view of the support member according to the invention, showing the female coupling structure.

FIG. 3 is a top view of a support column using the support member in FIG. 1, showing the square lateral cross section of the constructed support column and the alternating sets of pairs of support members.

FIG. 4 is a perspective view of the support column in FIG. 3, showing the staggered beam arrangement of the support members.

DRAWINGS LIST OF REFERENCE NUMERALS

The following is a list of reference labels used in the drawings to label components of different embodiments of the invention, and the names of the indicated components.

• 10 bearing member
• 12 top side of bearing member
• 14 bottom side of bearing member
• 16 beam side of bearing member
• 18 side wall
• 20 beam
• 30 male coupling structure
• 40 female coupling structure
• 22 beam end
• 100 support member
• 200 support column
• 300 first set of support members
• 300′ second set of support members

DETAILED DESCRIPTION

The inventor uses the term support member here to mean an individual block or crib, and support column to mean a series of cribs or support members stacked to form a secondary roof support column.

Referring now to FIG. 1, the improved crib or support member 100 according to the invention is typically comprised of a pair of bearing members 10 on opposite sides of a beam 20. Each bearing member 10 is comprised of a top side 12 and a bottom side 14 held together by 3 side walls 18, and a beam wall 16, the beam wall 16 of each bearing member 10 affixed to an opposing beam end 22. In some embodiments, such as the one illustrated in FIG. 1, the beam wall 16 is chamfered or otherwise shaped to meet the beam end 22, the beam wall 16 comprising a frustrum of a pyramid or a truncated pyramid having a larger base and a parallel smaller base, the beam end 22 affixed to the smaller base. In other embodiments (not shown), the beam wall 16 is of the same configuration as the side walls 18. In FIGS. 1-4, the beam wall 16 is a truncated pyramid having two square bases. In other embodiments (not shown), the truncated pyramid may include a pair of bases that are not the same shape, for instance, the larger base may be a square and the smaller base affixed to the beam may be a circle or some other shape, corresponding with the overall shape of the beam 10.

Referring to FIGS. 1 and 2, each bearing member includes on its top side 12 at least one male coupling structure 30, formed as an alignment nipple molded into the bearing member 10. At least one female coupling structure 40, formed as a receiving groove is molded onto the bottom side 14 of the bearing member 10, and is shaped so as to removably mate with the male coupling structure 30. In other embodiments (not shown), two or more mating structures 30 40 may be present on the top and bottom sides of the bearing members, and may be arranged about the periphery of the top and bottom sides, or located centrally, as desired.

The support member 100 is typically constructed of a structural polyurethane material that is poured or blown into forms. In some embodiments, the support member may formed from a mix of polyurethane and another material such as metal mesh, cardboard, wood dowels or fibers. The material used to form the support members is ideally strong, uniform, lightweight, and fire resistant compared to a similar sized hardwood crib. Compared to a typical hardwood crib, the support member according to the invention is about 75% lighter, and about 100% lighter compared to a concrete stacking oval as known in the prior art. The “dog bone” or “dumbbell” shape of the support member as shown in the Figures, reduces the overall weight of the support member 100, as well as permits light and air circulation through a constructed support column 200. The “dog bone” shape also allows for faster and easier handling of the support members and construction of the support column 200, as it allows the support member to be picked up, by the beam, with one hand, instead of using two hands to pick up a traditional rectangular shaped crib.

Referring now to FIGS. 3 and 4, the support column 200 is constructed by stacking sets of support members. In the embodiment shown in FIGS. 3 and 4, a set consists of a pair of support members. A first set 300 of support members is arranged in parallel spaced apart relationship on a floor of a mine tunnel with the bottom side 14 of the bearing members 10 adjacent the floor, and the top side 12 facing a roof of the mine tunnel. A second set 300′of support members with the bottom sides 14 facing the top sides 12 of the first set 300 is stacked onto the first set 300 but turned 90 degrees so that the beams of the second set 300′ are perpendicular to the beams of the first set 300. The mating structures 30 40 are locked together by applying pressure on the bearing members 10. More sets of support members 300 300′ are stacked, repeating the same pattern as the first and second sets, until a column shaped as a right prism with a hollow core and having a square lateral cross section is formed. The stacking of sets is continued until the last set is forced beneath the roof, typically reaching about 8 feet in height. The support members 100 typically are between 30 and 36 inches in length, but can be as long as 48 inches. The height and width of the bearing members are typically 4 inches by 6 inches, respectively, although the dimensions of the bearing members can be any desired size as long as they are taller than the height of the beam 20, to maintain the “dog bone” shape of a slender middle section with widened or flared ends.

FIG. 3 is a top view of the support column 200 and shows a square lateral cross section formed by the alternating stacking pattern of pairs of support members 100. It should be noted that while the square cross section is a typical embodiment of the support column 200, other cross sectional shapes are possible, such as octagonal, where the first and second sets of support members 300 300′ consist of 4 support members, where the first set is placed on the floor forming a square with open corners, and the second set 300′ is placed so as to join the bearing members of the first set, forming an octagon. In this embodiment, the male and female coupling structures are formed so as to allow locking the bearing members at angles other than at right angles shown in FIG. 3. Other shapes, including irregular prisms, may be constructed to accommodate differing conditions in the mine tunnel, including equipment that may be permanently or temporarily installed in or near the support column 200. In all these possible embodiments, the first set and the second set 300 300′ must have the same number of support members. It is important to note that as few as one set of support members, defined as two or more support members, can also form a support column 200.

It is to be understood that the above-described arrangements are only illustrative of the application of the principles of the present invention. Numerous modifications and alternative arrangements may be devised by those skilled in the art without departing from the scope of the present invention.

Claims

1. A support member (100) suitable for constructing a support column (200) used in a mine tunnel as a secondary support structure between a mine roof and a mine floor, the support member comprising:

a pair of bearing members (10), each bearing member comprising a planar top side (12) opposed to a planar bottom side (14), the planar top side and the planar bottom side held in spaced apart relation by a beam side (16) sandwiched between the planar top side and the planar bottom side;

a beam (20) having two opposing ends (22), the beam side (16) of each bearing member (10) affixed to an opposing end (22) of the beam (20); and

wherein the planar top side (12) is further formed with a male coupling structure (30), and the planar bottom side (14) is further formed with a female coupling structure (40) adapted to receiving the male coupling structure (30).

2. The support member of claim 1, wherein the beam side (16) is chamfered.

3. The support member of claim 2, wherein the beam side (16) is a truncated pyramid.

4. The support member of claim 1, wherein the support member is comprised of polyurethane.

5. The support member of claim 1, wherein the support member is comprised of polyurea.

6. The support member of claim 1, wherein the bearing member is about 4 inches tall and the total length of the support member is about 24 inches.

7. The support member of claim 1, wherein the bearing member is about 12 inches wide and the total length of the support member is about 48 inches.

8. The support member of claim 1, wherein the support member is made of a mix of polyurethane and wood.

9. The support member of claim 1, wherein the support member is made of a mix of polyurethane and metal mesh.

10. The support member of claim 1, wherein the support member is made of a mix of polyurethane and cardboard.

11. The support member of claim 1, wherein at least one of the beam (20) and the bearing members (10) is further comprised of a hollow interior core.

12. The support member of claim 11, wherein the hollow interior core is filled with at least one of limestone, sand, glass, polystyrene, and rubber.

13. A method of constructing a roof support column (200) suitable for supporting a roof of a mine by spanning an interior space of the mine from a floor of a mine to the roof, the method of constructing the roof support column comprising:

obtaining at least a first set (300) of support members (100), each support member (100) having a pair of bearing members (10), each bearing member having two opposing sides, the bearing members affixed to and held in spaced apart relationship by a beam (20), each bearing member including a female coupling structure (40) adapted to receiving a male coupling structure (30), the female coupling structure and the male coupling structure formed on opposing sides of the bearing members and parallel to the beam; and

laying the support members (100) of the first set (300) in parallel spaced apart relationship on the floor, with the female coupling structure of each bearing member adjacent to the floor and the male coupling structure facing the roof to form the roof support column (200) whereby the roof is supported.

14. The method of claim 13, further comprising at least a second set (300′) of support members (100) and further comprising after the step of laying the first set (300), the step of:

stacking the support members (100) of the second set (300′) in parallel spaced apart relationship on top of the first set (300) such that the second set (300′) is turned 90 degrees relative to the first set (300) and the beams of the second set (300′) are perpendicular to the beams of the first set (300), with the female coupling structures of the second set (300′) mating with the male coupling structures of the first set (300); and

obtaining a plurality of sets of support members and repeating the stacking of sets until a last set of support members contacts the roof, the sets of support members forming the roof support column (200) whereby the roof is supported.

15. A roof support column (200) constructed using the method in claim 13, wherein the support column (200) is between 30 to 36 inches wide.

16. A roof support column (200) constructed using the method in claim 13, wherein the at least a first set (300) of support members (100) comprises two support members.

17. A roof support column (200) constructed using the method in claim 14, wherein the support column (200) is between 30 to 36 inches wide.