US3885395A

US3885395A - Underground mining arch gateway system

Info

Publication number: US3885395A
Application number: US344926A
Authority: US
Inventors: Jens Hilligso Madsen
Original assignee: Individual
Current assignee: Contech Engineered Solutions LLC
Priority date: 1972-12-29
Filing date: 1973-03-26
Publication date: 1975-05-27
Anticipated expiration: 1992-05-27
Also published as: CA981473A

Abstract

This invention relates to a corrugated steel arch gangway system used in a method of mining an underground ore body. Commencing at the bottom of the ore body, successive horizontal cuts or layers are excavated, processed and backfilled with tailings from the processing. An arch shaped longitudinal horizontal portion of the gangway system is erected on the floor of the first lower cut and a plurality of first and second hollow extendible upward extending vertical portions are connected thereto by transverse horizontal portions. The horizontal portion of the gangway system is covered by a layer of backfill and then the first vertical portions or manways provide access from the horizontal portion to successive upward adjacent cuts which are mined and the ore is removed through the second vertical portions or millholes to a railway operating in the horizontal portion of the gangway system. As each cut is excavated, it is backfilled by a cemented hydraulic backfill following extension of the vertical portions. The longitudinal horizontal portion of the gangway system is constructed of a plurality of overlapping arch shaped sections, each of which is formed of a flat based member and first and second curved wall members. The members and the sections are initially positioned by being bolted together, and then securely connected by a plurality of self-drilling screws spaced along the joints.

Description

United States Patent Madsen May 27, 1975 UNDERGROUND MINING ARCH GATEWAY [57] ABSTRACT SYSTEM This invention relates to a corrugated steel arch gang- [76] Inventor: Jens Hilligso Madsen, 60 Brentwood y System used in a method of mining under Dr" Guelph Ontario, Canada ground ore body. Commencing at the bottom of the ore body, successive horizontal cuts or layers are ex- [22] Filed: 1973 cavated, processed and backfilled with tailings from [21] APPL No: 344,926 the processing. An arch shaped longitudinal horizontal portion of the gangway system is erected on the floor of the first lower cut and a plurality of first and second [30] Apphcamm Pnoniy Data hollow extendible upward extending vertical portions Dec. 29, I972 Canada 161720 are connected thereto by transverse horizontal portions. The horizontal portion of the gangway system is [52] U.S. Cl. 61/45 R; 61/63 covered by a layer of backfill and then the first verti- [5 1] Int. Cl E21d 19/00 cal portions or manways provide access from the hori- [58] Field Of ear 61/45 zontal portion to successive upward adjacent cuts 169 which are mined and the ore is removed through the second vertical portions or millholes to a railway oper- [56] References Cited ating in the horizontal portion of the gangway system.

UNITED STATES NT As each cut is excavated, it is backfilled by a ce- 1,981,4l7 ll/l934 Kreutzer 52/86 x memed hydrfwlic backfi" F Q f of F 2,185,532 [/1940 Waterman et aL 52/86 X vertical portions. The longitudinal horizontal portion 2,871,802 2/1959 Fishler 52/169 X of the g g y System is Constructed of a plurality of 3,034,607 5/1962 Haines 52/86 X overlapping arch shaped sections, each of which is 3.0 9.835 /19 Sundst m 52/l69 formed of a fiat based member and first and second 3.057.! 19 10/ fl 52/86 X curved wall members. The members and the sections 3993-097 6/l963 Rosenfeld 52/169 x are initially positioned by being bolted together, and

3,159,? [2/1964 Rosenfeld 52/l69 X then Securely connected a plurality f Self-{killing Primary ExaminerDennis L. Taylor screws spaced along the joints.

10 Claims, 5 Drawing Figures PATENTEnmzvlars 3,885,395

sum 1 UNDERGROUND MINING ARCH GATEWAY SYSTEM BACKGROUND OF THE INVENTION DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference is first made to FIG. 1 which partially This invention relates generally to a method of min- 5 Shows a Corrugated Steel gangway System having ing wherein an ore body is progressively excavated and replaced by a pneumatic or hydraulic backfill, and more particularly to a corrugated steel arch gangway system and apparatus for carrying out such a method. 10

In the past, it has been known to mine ore bodies by progressively excavating horizontal cuts and replacing them with horizontal layers of pneumatic or hydraulic backfill. However, these previous methods have utilized gangway systems constructed of a combination of heavy fir timbers, lighter timber lagging and a flexibie water tight membrane covering. Timber gangway systems have the gradually increasing disadvantage that they are expensive in that suitable timber is becoming more scarce and therefore costly and installation of the systems is time consuming and labour costs are continually increasing. In addition, timber gangway systems have the disadvantage that transportation of the timber both in the mine and above ground is costly and inconvenient. Furthermore, the completed gangway systems present a substantial firehazard, and the heavy cross timbers impede the flow of ventilating air in the mine.

More recently, alternate methods using other materials have been attempted, but these have proven to be unsatisfactory in that erection of the gangway systems have been too time consuming and/or the erected gangway system has not been sufficiently structurally stable.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to at least partially overcome these disadvantages by providing a corrugated steel arch gangway system which may be economically manually erected and which is relatively structurally stable when erected.

To this end, in one of its aspects, the invention provides a gangway system having a longitudinal horizontal portion formed of a plurality of overlappingly connected arch shaped sections, each section comprising a flat corrugated steel base member having first and second ends; a first corrugated steel curved wall member having upper and lower ends, the lower end adapted to be securely connected to the first end of the base member; and a second corrugated steel curved wall member having upper and lower ends, the lower end adapted to be securely connected to the second end of the base member, the upper end adapted to securely connected to the upper end of the first wall member.

Further objects and advantages of this invention will appear from the following description, taken together with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial perspective view of a gangway system according to a preferred embodiment of the invention;

FIGS. 2 to 4 are sectional views showing progressive steps in a method of mining using the preferred em bodiment of the invention; and

FIG. 5 is a sectional view along line V-V in FIG. 3.

arch shaped longitudinal horizontal portion or gangway 12, a cylindrical first vertical portion or manway l4, and a cylindrical transverse horizontal connecting portion l6. In practice, the longitudinal horizontal portion 12 of the gangway system 10 is erected in a mine to extend horizontally in the stope across the entire ore body, or in some cases may have junctions (not shown) to form a horizontal network extending through a desired portion of the ore body. Normally, the gangway system 10 has additional vertical first portions 14 and transverse horizontal portions 16 identical to those shown having suitable steps or stairs (not shown) lo cated at desired intervals along the length of the longitudinal portion 12 to form manways to provide access to successive upper horizontal cuts in the stope. In addition, similar second vertical portions 17 (shown in FIG. 5) are also spaced along the longitudinal horizontal portion 12 and extend upwardly therefrom to provide millholes. As shown, the longitudinal horizontal portion 12 is formed large enough to accommodate mine cars on track 18 to carry ore received through the second vertical portions or millholes 17 to conventional means for crushing the ore and removing it from the mine for processing.

In more detail, the longitudinal horizontal portion 12 is formed of a number of identical overlapping arch shaped sections 20. Each arch shaped section 20 is in turn formed of a flat corrugated steel base member 22, a first corrugated steel curved wall member 24 and a second corrugated steel curved wall member 26. Each arch shaped section 20 may be erected by a crew of men by positioning the base member 22 on substantially flat floor 28 and then connecting the

wall members

24, 26 to it. The first wall member 24 is placed in an upright position and its lower end 30 is attached to a first upwardly flanged end 32 of the base member 22 by one or two nuts and bolts (not shown) inserted through co-operative bolt holes therein. The second corrugated steel curved wall member 26 is then placed in an upright position, its lower end 36 is similarly attached to a second upwardly flanged end 38 of the base member 22 and its upper end 40 is attached to the upper end 42 of the first wall member by nuts and bolts 43. The arch shaped sections 20 may be formed of 12 gage corrugated steel with a 2 h inch pitch and 1% inch depth, and the

wall members

24, 26 are normally two feet wide which permit them to be manually erected, although of course, mechanical erection assistance devices may also be used. In this position, the erected arch shaped section 20 is sufficiently stable to support its own weight, and additional base members 22 and

wall members

24, 26 may be attached thereto to form additional arch sections 20 and thereby longitudinal horizontal portion 12. Adjoining arch shaped sections 20 overlap at circumferential seams 44 and are initially attached together by bolts 46 passing through matched holes therein. Although bolts 46 are shown only as being common with some of the bolts 43 which hold the

members

22, 24, 26 of the arch shaped sections together, they may also be spaced along the circumferential seams 44.

As the longitudinal horizontal portion [2 is erected, the corresponding ends of the members forming the arch shaped sections 20, and the circumferential seams 44 between the arch shaped sections are securely attached by a plurality of self-drilling screws 48 inserted therethrough, spaced at approximately ten inch intervals. As may be seen the

upper ends

40, 42 of the first and

second wall members

24, 26 form a peak 49, and the

lower ends

30, 36 are located outside of the first and

second ends

32, 38 of the base member 22. Although this structure in itself assists in providing that the erected longitudinal horizontal portion 12 is relatively watertight, a suitable caulking compound may also be used if required. In addition the screws 48 may be provided with suitable means such as neoprene gaskets which reduce leakage. Although the longitudinal horizontal portion is structurally stable to withstand external forces when erected, it may be desirable from a safety point of view to provide temporary internal support during introduction of the backfill (as described below). This support may be provided by conventional timber or steel shoring temporarily positioned in the horizontal longitudinal portion 12.

As described above, transverse horizontal portions 16 extend laterally from the longitudinally horizontal portion 12 at desired intervals along its length. Each transverse horizontal portion 16 is formed of a number of overlapping cylindrical corrugated steel sections 50 which are securely connected together in a manner similar to that described above in regard to the longitudinal horizontal portion 12. Each transverse horizontal portion 16 is closed at its outer end 52 by a bulkhead 54 secured to the outermost cylindrical section 50. The second corrugated curved wall members 26 of several arch shaped sections 20 of the longitudinal horizontal portion 12 are especially shaped to receive the inner end 56 of the transverse horizontal portion 16. Transitional steel plates 58 may be bolted, welded or fastened with self-drilling screws in place to make the connection. However, it is pointed out that the amount of welding required must be kept to a minimum as underground welding of galvanized steel is undesirable due to the production of toxic gases.

The lower end 60 of the first vertical portion or manway 14 forms a similar substantially watertight connec tion with the transverse horizontal portion 16. The first vertical portion 14 is also formed of a plurality of overlapping corrugated steel sections 62 which are secured together by nuts and bolts 43 and self-drilling screws 48 and extends upward above the longitudinal horizontal portion 12. In the preferred embodiment shown, the longitudinal horizontal portion 12 is approximately nine feet in height, and the upper end 64 of the first vertical portion 14 extends to a height of approximately 15 feet above the floor 28 of the stope. The first vertical portion is cylindrical in shape with a diameter of approximately 6 feet, and has conventional stairs located therein to provide access to the working level of the mine.

Also extending upward from and spaced along the elongated horizontal portion 12 are second vertical portions or millholes 17. The second vertical portions are also formed in sections and have upper ends 65 which are extendible, but must be structurally stronger than the first vertical portions 14 to withstand the passage of ore therethrough. Therefore, in the preferred embodiment, the second vertical portions 17 are cylindrical in shape with a diameter of 6 feet and are formed of l inch flat steel plate.

Although a gangway system 10 is shown with only a longitudinal portion 12, manways 14 and millholes 17, it is apparent that similar portions may be connected in a similar manner to the system to form other structures such as ventialtion ducts.

Although the transverse horizontal portion 16 and the first and second

vertical portions

14, 17 are all shown as being cylindrical in shape, it is apparent that they may be formed of other shapes which are suitable for use as manways and millholes.

In use, referring to FIGS. 2 to 5, a first lower horizontal cut 66 of an ore body 68 is first excavated and the ore is crushed and removed to the surface for processing in a conventional manner. Substantially fiat level floor 28 is formed by pouring a thin slab 69 of hydraulic backfill in the bottom of the first cut 66. A gangway system 10 according to the invention is then erected on the floor 28 with the upper ends 64, of the several first and second

vertical portions

14, 17 extending towards the ceiling 70 of the first cut 66. As mentioned above, a railway track 18 is normally laid on ballast 71 along the longitudinal horizontal portion 12 to provide for transportation of the ore out of the gangway system 10 to a crusher (not shown) and then through a vertical shaft (not shown) to a surface mill for processing.

Following erection of the entire gangway system 10 and after the various members have been securely connected together using the self-drilling screws 48, backfill 72 (see FIG. 3) is introduced into the first cut 66 to a depth sufficient to cover the longitudinal horizontal portion 12 but not sufficient to reach the

upper ends

64, 65 of the

vertical portions

14, 17. This backfill 72 is normally a cemented hydraulic backfill consisting of tailings from the surface mill combined with cement in approximately the proportions of 32 to l, with an 8 to l mix used for the floors.

in some applications it is preferable to use alluvial sand or other available material instead of or in combination with the tailings. Alternatively it will be apparent to those skilled in the art that a pneumatic backfill formed from the tailings and/or other available material may also be used. As mentioned, during introduction of the hydraulic backfill, caulking of the joints between the various members of the gangway system 10 may be desirable to reduce leakage of the backfill into the interior of the gangway system 10. After solidification of the hydraulic backfill 72 to form a first consolidated backfill layer 73, ore is mined from the ceiling 70 of the first lower cut 66 and remove through the nearest millhole formed by vertical portions 17 to the railway operating in the longitudinal horizontal portion 12, to form a second horizontal cut 74 upwardly adjacent from the first horizontal cut 66. FIG. 5 shows that first and second

vertical portions

14, 17 are longitudinally spaced along the length of the horizontal portion 12 at desired intervals to provide sufficient access to and allow economic removal of the ore from the second cut 74.

Following excavation of the second cut 74, the first vertical portions or manways 14 are each extended towards the ceiling 76 of the second cut 74 by adding several cylindrical sections 62. These sections 62 are erected and securely connected using nuts and bolts 43 and self-drilling screws 48 as described above. Similarly, the second vertical portions or millholes 17 are extended to approximately the same level. Additional hydraulic backfill 72 is then introduced into the second horizontal cut 74 on top of the first consolidated backfill layer 73 to a level near the upper ends 64, 65 of the extended vertical portions l4, l7 and permitted to harden to form a second consolidated backfill layer (not shown). This process of alternatively excavating successive upwardly adjacent ore cuts, extending the vertical portions and forming successive consolidated backfill layers is repeated several times to remove a substantial vertical portion of the ore body through longitudinal horizontal portion 12. In the preferred embodiment shown, each cut is approximately twelve feet in height, and it has been found economically desirable to erect another longitudinal horizontal portion 12 rather than further extending the vertical portions l4, 17 following excavating and backfilling approximately ten successive cuts. This, of course, may vary with conditions such as the type of ore in each case.

The initial introduction of backfill 72 around the longitudinal horizontal portion 12 of the hollow gangway system exerts an upward force on the system 10 with the resulting danger of flotation of the system 10 in the backfill 72. It is apparent that flotation of any portion of the longitudinal horizontal portion 12 in cemented hydraulic backfill would create a very serious problem. Although this danger may be overcome by securely anchoring the gangway system 10 to the floor 28, this solution is expensive and labour consuming. It has been found that while a cylindrical shaped structure ofa sub stantial length may indeed float under these conditions, the present arch shaped structure is substantially flotation resistent as the backfill 72 does not flow beneath the flat base members 22 and approximately 80 percent of the curvature of the

curved wall members

24, 26 contributes to resisting flotation. The shape of the base members 22 and

wall members

24, 26 has the added advantage that it permits nesting of the members during transportation prior to underground erection.

The present method has an advantage that it is not necessary that the gangway system 10 be designed to be able to withstand external loading during erection. ln addition, loading due to the introduction of backfill around the erected longitudinal horizontal portion 12 is substantially uniformly applied from opposite sides and while temporary shoring may be desirable (as mentioned above), it may be kept to a minimum. Furthermore, it has been found that following formation of two or more backfill layers above the longitudinal horizontal portion 12, impact loading due to mining operation on successive upward cuts has no effect on the longitudinal horizontal portion 12 due to bridging action of the consolidated backfill.

Although the disclosure describes and illustrates a preferred embodiment of the gangway system, it is to be understood the invention is not restricted to this particular embodiment.

What I claim is:

l. A gangway system manually erectable within confined underground openings excavated during backfill mining to provide a horizontal network for the progressive excavation of ore, comprising a plurality of interconnected elongated horizontal portions erectable underground in a confined space in communication with a plurality of first and second vertical portions, said horizontal portion being formed of a plurality of overlappingly connected arch shaped sections comprising:

a. a flat corrugated steel base member having first and second ends and adapted to support mine cars on tracks,

b. a first corrugated steel curved wall member having upper and lower ends, said lower end adapted to be securely connected to said first end of said base member, and

c. a second corrugated steel curved wall member having upper and lower ends, said lower end adapted to first be securely connected to said second end of said base member, said upper end adapted to then be securely connected to said upper end of said first wall member,

said horizontal portions being adapted to be buried in a first layer of backfill after erection with said vertical portions projecting upward therefrom through said first layer of backfill to an upward horizontal ore layer, said vertical portions being upwardly extendible to project through successive upward horizontal backfill layers to successive upward horizontal ore layers, said vertical portions being spaced to provide access to said successive ore layers and for economical removal of ore downwardly therethrough to said horizontal network.

2. A gangway system as claimed in claim I further including a plurality of hollow transverse horizontal portion extending laterally from the longitudinal horizontal portions and the lower end of a corresponding one of the first vertical portion to communicate first vertical portion with said longitudinal horizontal portion.

3. A gangway system as claimed in claim 2 wherein the transverse horizontal portions and the first vertical portions are formed of corrugated steel.

4. A gangway system as claimed in claim 3 wherein the transverse horizontal portions and the vertical por tions are cylindrically shaped.

5. A gangway system as claimed in claim 4 wherein the second vertical portions are cylindrically shaped and formed of one inch steel plate.

6. A gangway system as claimed in claim 1 wherein each of the first vertical portions include vertically extending stairs.

7. A gangway system as claimed in claim 1, wherein the said ends of the base member and the first and second wall members of each section are adapted to be overlappingly connected.

8. A gangway system as claimed in claim 1, wherein the said ends of the base member and the first and second wall members of each section have matching bolt holes therethrough and are adapted to be initially overlappingly positioned by nut and bolt engagement therein and then securely overlappingly connected by a plurality of spaced self-drilling fasteners extending therethrough.

9. A gangway system as claimed in claim 1 wherein adjoining arch shaped sections have circumferentially spaced matching bolt holes therethrough and are adapted to be initially positioned by nut and bolt engagement therein and then securely overlappingly connected by a plurality of circumferentially spaced selfdrilling fasteners extending therethrough.

10. A gangway system as claimed in claim 1 wherein the base member and the first and second wall members of each section are formed of 12 gauge corrugated steel ofsubstantially a 2 inch pitch and a inch depth. k i

Claims

1. A gangway system manually erectable within confined underground openings excavated during backfill mining to provide a horizontal network for the progressive excavation of ore, comprising a plurality of interconnected elongated horizontal portions erectable underground in a confined space in communication with a plurality of first and second vertical portions, said horizontal portion being formed of a plurality of over-lappingly connected arch shaped sections comprising: a. a flat corrugated steel base member having first and second ends and adapted to support mine cars on tracks, b. a first corrugated steel curved wall member having upper and lower ends, said lower end adapted to be securely connected to said first end of said base member, and c. a second corrugated steel curved wall member having upper and lower ends, said lower end adapted to first be securely connected to said second end of said base member, said upper end adapted to then be securely connected to said upper end of said first wall member, said horizontal portions being adapted to be buried in a first layer of backfill after erection with said vertical portions projecting upward therefrom through said first layer of backfill to an upward horizontal ore layer, said vertical portions being upwardly extendible to project through successive upward horizontal backfill layers to successive upward horizontal ore layers, said vertical portions being spaced to provide Access to said successive ore layers and for economical removal of ore downwardly therethrough to said horizontal network.

2. A gangway system as claimed in claim 1 further including a plurality of hollow transverse horizontal portion extending laterally from the longitudinal horizontal portions and the lower end of a corresponding one of the first vertical portion to communicate first vertical portion with said longitudinal horizontal portion.

4. A gangway system as claimed in claim 3 wherein the transverse horizontal portions and the vertical portions are cylindrically shaped.

9. A gangway system as claimed in claim 1 wherein adjoining arch shaped sections have circumferentially spaced matching bolt holes therethrough and are adapted to be initially positioned by nut and bolt engagement therein and then securely overlappingly connected by a plurality of circumferentially spaced self-drilling fasteners extending therethrough.

10. A gangway system as claimed in claim 1 wherein the base member and the first and second wall members of each section are formed of 12 gauge corrugated steel of substantially a 2 2/3 inch pitch and 1/2 inch depth.