Patent Application
20060105695
This invention relates generally to mine ventilation structures and more particularly to a mine ventilation structure anchored in the mine.
Structures which can be easily assembled and disassembled have many applications, but are particularly useful in underground mining operations where sturdy, but temporary structures are required. An example of such a structure is a mine ventilation structure at the intersection of two mine passageways for separating the air flow in the two passageways. Such a structure is shown in co-assigned U.S. Pat. Nos. 5,466,187 and 6,264,549, which are incorporated herein by reference.
For example, overcast and undercast mine ventilation structures are widely used in underground mining to prevent the mixture of forced (or induced) ventilation air flowing through a first mine passageway with forced (or induced) ventilation air flowing through a second mine passageway at the intersection of those passageways. An overcast ventilation structure is a tunnel erected in the first passageway and extending through its intersection with the second passageway. The tunnel blocks communication of air between the first passageway and the second passageway at the intersection, but permits air in the second passageway to travel through the intersection in a passage created by a space between the roof of the tunnel and the mine passageway ceiling. An undercast is of similar construction, except that the air in the second passageway passes under the erected tunnel in a slot cut in the floor of the mine passageways at the intersection. In both cases, there is a large flat deck that is subjected to the air pressure flowing through the mine.
As mines get bigger and deeper, there is a greater emphasis on proper ventilation. Consequently, ventilation pressure in the mine increases greatly. The increased pressure causes new problems for ventilation structures. In the case of an overcast or undercast, increased pressure under the deck subjects the deck to a large uplift force.
For example, an overcast defining a 20×30 foot tunnel may include a deck comprising 15 sections, each measuring 20×2 feet and weighing about 15-20 pounds. If the mine air pressure is 20 inches water gauge (0.0361 psi), each section is subjected to an uplift force of about 4200 pounds, and the total uplift force on the deck is about 62,400 pounds. Obviously, the overcast will be unstable due to the uplift force and will need to be strengthened.
Prior art solutions to the problem have included ballasting the deck, as by pouring concrete or similar material on it, or placing props between the roof and the deck. The concrete makes the structure permanent so that it cannot be re-used, thereby increasing the cost of the structure. The concrete itself also increases the cost of the structure. The props are unsatisfactory because mine roofs tend to converge or move closer to the floor over time. Such convergence will cause the props to crush the deck.
In one aspect of the invention, a ventilation structure for installation at intersecting mine passages comprises first and second generally parallel side walls. Each side wall is of such height as to wall off at least a portion of a respective mouth of the first airway. A deck extends between the side walls and is connected thereto. A mooring system includes first and second anchors extending into and fixed to at least one of the mine floor and the mine ribs. The first and second anchors are connected to and fixed relative to the side walls and deck so as to restrain upward movement of the structure.
In another aspect, an overcast at the intersection comprises the first and second side walls and a deck extending over the side walls. The mooring system includes a plurality of anchors, each anchor being fixed in the mine floor, and a plurality of restraining members.
Other features will be in part apparent and in part pointed out hereinafter.
Corresponding reference characters indicate corresponding parts throughout the drawings.
Referring to
Referring also to
In this embodiment, each of the side walls 21 of the tunnel-forming overcast 19 comprises a plurality of elongate generally vertically extensible panels 25, the panels in each side wall extending generally vertically in side-by-side relation. As herein illustrated, each side wall 21 is arbitrarily shown as comprising twenty-four of such panels. Each panel 25 is suitably of the type used in the mine stopping shown in the coassigned U.S. Pat. No. 6,264,549 dated Jul. 24, 2001, or the panel used in the stopping in the coassigned Ser. No. 10/951,116 filed Sep. 27, 2004, both of which are incorporated herein by reference, each said panel comprising a vertically extensible upper member herein numbered 27 and a lower member herein numbered 29, the latter having a telescoping sliding fit in the former. The side walls 21 may include sections and/or be adapted for quick-connection as shown in coassigned U.S. patent application Ser. No. 10/266,182, filed Oct. 7, 2002 and incorporated herein by reference. The panels may be non-extensible within the scope of the invention.
Each side wall 21 has a shelf or header 39 at the top extending over the upper ends of the upper panel members thereof corresponding to shelf 70 of U.S. Pat. No. 5,412,916 which is incorporated herein by reference. The shelf is suitably secured on the upper panel members 27 of the panels of each side wall 21, and may have the support of gussets 41 corresponding to those shown at 74 in this '916 patent. The deck 23 is essentially the same as that shown in the '916 patent but, instead of merely resting at its ends on the side walls, is connected to the shelf and thus to the upper panel members 27 of the extensible panels 25 of the side walls. The connection of the deck 23 to each shelf or side wall may be generally the same as the bayonet-slot type of connection shown in the aforesaid U.S. Pat. No. 5,412,916, or by other suitable means, including but not limited to riveting. The structure is strengthened by making the deck fixed relative to the side walls so that the deck is in effect a fixed beam (rather than a simple beam).
As shown in this embodiment, as to each side wall 21, the upper panel members 27 of the panels 25 extend down from the respective shelf 39 in side-by-side relation, and the lower panel members 29 extend down from the upper panel members 27 to their respective footers 45 that engage the floor 7. The panels 25 are held in the stated relation by reason of the upper panel members 27 being fastened to the shelf or header 39 and by suitable means, such as a bar and wire ties in generally the same manner as shown for the bars and wire ties in our aforesaid mine stopping patents, by the means shown in the aforesaid Ser. No. 10/951,116, or by other suitable means.
Referring more particularly to
Each cable 55 includes a first end 71 attached to one of the brackets 53 on one side wall 21 and a second end 72 attached to an opposite bracket on the other side wall so that the cable extends over the deck 23 and side walls 21. In this embodiment, each cable 55 is generally parallel with the longitudinal axes of the panels forming the deck 23 and side walls 21. Each cable 55 includes a turnbuckle 75 interposed between its ends 71, 72 (
There are five cables 55 (broadly, restraining members) in this embodiment, though any number may be used within the scope of the invention, including only one. Suitable cables are made of steel or other suitable material. Additionally, other types of restraining members are contemplated within the invention, including but not limited to straps, wires, chains, guys, rods or lines. Alternatively, one long, continuous cable may be substituted for the several cables, the long cable being “laced” through the brackets and fixed to only two of the brackets.
Where the side walls 21 and deck 23 are fixed relative to one another, a restraining member fixedly connected to either of the side walls or the deck is thereby connected to both the side walls and the deck. The restraining members need not necessarily extend over the deck, but may be secured to (directly or indirectly) or be integrally formed with the side walls or the deck. The restraining members may also be made to eliminate the need for brackets or other means of connecting the anchors to the side walls. For example, the bottom of the side wall 21 may be formed so that the anchor may bear directly against the side wall (the bracket being omitted). The restraining member may comprise a footer (such as footer 45) disposed at the bottom of the side wall and have an opening (not shown) receiving the anchor to restrain the side wall. In such case, if the deck is fixed relative to the side walls (as by an interlocking relationship), the anchors are thereby connected to the deck and side walls, and the entire structure is restrained against upward movement.
In this embodiment, there are ten anchors 57, one through each of the ten brackets 53. The anchors 57 are suitably anchor bolts (broadly, anchors), such as self-anchoring bolts, extending into and fixed to the mine floor 7. Alternatively, the anchors 57 may be permanently attached to the brackets 53. Further, the anchors may extend into and be fixed to the mine ribs 8 or roof 9. Other types of anchors may be used within the scope of the invention.
In a method of installation, the side walls 21 and deck 23 are installed, as by any of the methods described in the above-referenced patents and patent applications. The brackets 53 are installed beneath some of the side wall panels 25. One of the anchors 57 is placed through each bracket 53 and driven into the mine floor 7. The first end 71 of one of the cables 55 is threaded through the hook 61 on one of the brackets 53 and secured, as by crimping (
The mooring system may also be used with an undercast. In an undercast, the deck extends between the footers of the side walls, opposite ends of the deck engaging the mine floor. In one example, anchors are secured to the mine floor outside the side walls adjacent the deck ends. The restraining members need not necessarily extend over the side walls. The restraining members extend over the deck ends of the undercast, extending between the panels of the side walls.
It is also contemplated that the overcast (or undercast) side walls and deck be formed as one piece, rather than having the deck be separable from the side walls. Further, the deck and/or side walls may be arched or curved.
When introducing elements of the present invention or the preferred embodiment(s) thereof, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.
In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.
As various changes could be made in the above constructions, products, and methods without departing from the scope of the invention, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.
