US3582138A

US3582138A - Toroid excavation system

Info

Publication number: US3582138A
Application number: US818986A
Authority: US
Inventors: Robert L Loofbourow; William Vaananen; William G Wood
Original assignee: Individual
Current assignee: Individual
Priority date: 1969-04-24
Filing date: 1969-04-24
Publication date: 1971-06-01
Anticipated expiration: 1988-06-01

Abstract

A system for excavating space deep in the earth in the form of a doughnut-shaped generally cylindrical annulus or toroid having a core of substantial diameter within which there is usually at least one central shaft for access to the workings and removal of rock from the excavation. The generally circular configuration of the excavation minimizes distances for access of men and equipment to the workings and removal of the rock and introduces efficiencies and cost savings resulting from minimum preparation, minimum travel distances, loading from a single station at the bottom of the shaft and is conducive to excellent working conditions.

Description

VII-Irv uwuvuu .l Dblllv TOROID EXCAVATION SYSTEM 1 1 Claims, 9 Drawing Figs.

US. Cl 299/13, 299/18, 299/19 Field of Search 299/1 1, 13, 18,19;61/0.5

H 13,5s2,13s

Primary Examiner-Ernest R. Purser Attorney-Burd, Braddock & Bartz ABSTRACT: A system for excavating space deep in the earth in the form of a doughnut-shaped generally cylindrical annulus or toroid having a core of substantial diameter within which there is usually at least one central shaft for access to the workings and removal of rock from the excavation. The generally circular configuration of the excavation minimizes distances for access of men and equipment to the workings and removal of the rock and introduces efficiencies and cost savings resulting from minimum preparation, minimum travel distances, loading from a single station at the bottom of the shaft and is conducive to excellent working conditions.

Pmmmu Inn 3582.138

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' INVliNI'ORS ROBERT L. LOOFBOUROW WILLIAM VAANANEN BY WILLIAM 6. W000 MWJW ATTORNEYS TOROID EXCAVATION SYSTEM This invention relates to a system for forming an excavation in rock in the form of a generally cylindrical annulus or toroid having a core of substantial size within which are located one or more access shafts. The objective of the system is the making of large stable underground openings in rock it! the least time and at the lowest possible cost. It is the objective of the system to make available high grade crushed rock aggregate at a minimum cost while providing an excavation suitable for storage, waste disposal, and the like. The invention is illustrated in the accompanying drawings in which corresponding parts are identified by the same numerals and in which:

FIG. I is a schematic vertical cross section through a typical planned excavation after completion of final preparation and prior to production;

FIG. 2 is a horizontal section taken generally along the line 2-2 of FIG. l and in the direction of the arrows, this being a plan of the top drill level;

FIG. 3 is a horizontal section taken generally along the line 3-3 of FIG. 1 and in the direction of the arrows, this being a plan of a middrill level;

FIG. 4 is a horizontal section on the line 4-4 of FIG. I and in the direction of the arrows, this being a plan of the haulage level;

' FIG. 5 is a fragmentary vertical section on an enlarged scale showing the excavation system ingreater detail;

FIG. 6 is a horizontal section generally on the line 6-6 of FIG. 5 and in the direction ofthe arrows;

FIG. 7 is a horizontal section generally on the line 7-7 of FIGS and in the direction of the arrows;

FlG. 8 is a schematic vertical section showing a layout for a second unit which may be excavated using the accessways of the first; and i FIG. 9 is a plan of such a layout for a second unit. Referring to the drawings, there is shown schematically a large rock mass 10 underlying the ground surface 11 at some Substantial depth ranging between about 100 and several thousands of feet depending upon the conditions present and objectives sought. The excavation 12 to be made is in the form of a generally cylindrical annulus or toroid having a core 13 of substantial size of diameter sufficient to support a substantial part of the stress increment which results from the excavation.

The situs is preferably at a convenient location near a place where there is large demand for low-cost stone or rock aggregate and-for large capacity storage or waste disposal space, such as near a large city. As shown, one or more vertical or inclined access shafts such as hoisting shaft 14 and man shaft 15 are located near the center of core 13. These shafts, for example, may be of the order of 6 to 12 feet in diameter and adapted to provide access for skips for hoisting of rock and transport of men and equipment suspended from suitable hoist means at the ground surface, not shown but well understood in the art.

While the entrance to the excavation will in most instances extend through the central core, in some instances an inclined entrance lying outside of the excavation annulus may be pro vided. For example, an inclined conveyor way from a central loading point for a belt conveyor or similar means may be used for removal of rock from the excavation. Depending upon the particular site and the conditions encountered there, the entrances may be vertical or inclined or helical or zigzagged in a vertical plane or a combination of these. They may be prepared by any suitable drilling or mining techniques well known in the art. In some instances it may be essential or preferred to extend the hoisting shaft or incline several hundred'feet below the main toroid excavation. For example, where the toroid excavation is to be used as a pumped storage reservoir, a powerhouse excavation is needed below the reservoir.

Preparatory to beginning excavation, a plurality of horizontal accessways or

headings

16, 16A are formed through the rock extending generally radially outwardly from the center of the core to the edges of the excavation to be formed. A plurality of concentric spaced apart horizontal

inner drill drives

17, 17A and

outer drill drives

18, 18A intersect the

accessways

16, 16A. Although the drill drives and haulageways are generally circular, the pattern in a horizontal is actually polygonal. For convenience, in opening these passageways, headings are run a specified distance on a given bearing and then turned by a given angle. Typical distances would be 75 to 150 feet and angles about 20. A further advantage of this pattern is the greater ease of setting up long-hole drills to work on parallel rings of holes or holes in parallel planes, than to have each ring on a very slightly different bearing as would be true if the pattern were a true circle. The drill drives are spaced apart both horizontally and vertically defining the perimeters of the excavation at their respective levels. The excavation levels are interconnected by at least one generally vertical slot raise 19 extending between the inner and outer drill drives.

Although illustrated with two spaced apart drill levels, the excavation may require only one drill level, or more than two, depending upon the height of the excavation. The drill drives are generally concentric but where more than on drill level is provided they need not be in vertical alignment. Instead it may be preferred that the excavation wall slope inwardly from the top to bottom. The topmost drill drive may take the form of a pilot heading of shallow height, such that the miners may reach the ceiling for removal of loose rock installation of rock bolts, etc., and of width corresponding to the projected width of the toroidal excavation. At least one slot extends from this drill drive to a lower haulageway. The long holes are drilled from above, and for toroids of lesser height only radial haulageways are provided, the rock being loaded through the to roid itself. I

Where excavations of lesser height are preferred, as, for example, where the toroid is to be used for pumped storage, long-hole drilling and haulage may be from a single level, the same generally circular passages serving both as drill drives and haulageways. Here the long holes are drilled from below and the rock is loaded and hauled through the toroid. In any of the variations described, where rapid excavation is an objective, two or more slots may be prepared and a production face advanced in each direction from each slot.

After the hoisting shaft 14 has been completed a pocket 20 is developed at, or sometimes below, the lowermost haulage level. Passways 21 are developed from the upper levels as needed so that all rock broken in preparatory workings can be loaded in bulk from a single loading station at the bottom of that shaft and removed. A plurality of haulageways 22 extend from near the bottom of the hoist shaft at the haulage level to a peripheral ring 23 at the bottom of the excavation which has a plurality of draw points 24 as needed. Bulk excavation proceeds by drilling and blasting holes on one or both sides of the slot 19. Broken rock is loaded on and hauled from the bottom of the slot to the loading station at the bottom of the hoisting shaft and raised to the surface.

Because of the location of the hoisting and man shafts in the central core within the annular excavation, the length of accessways leading from the shafts for movement of supplies, equipment and men to the working places is minimized. Similarly, the distance through which the broken rock is moved is minimized. The greatest planned haulage distance between drawpoint and apron feeder is about 200 feet and the average is only about feet. This permits efficient use of front end load, load-haul units which are operated independently by one man and are effective in cleaning their own roadways as well as in pushing aside oversize chunks for later blasting.

As the broken rock is withdrawn from each drawpoint 24, it

. is desirably loaded onto an apron feeder 25 to a crusher 26 in one of the haulage level accessways 22 located as close to the production area as feasible. From the crusher the crushed rock is desirably moved by conveyor 27 through an upwardly inclined conveyor way 28 to a surge bin 29 above the loading pocket 20 from which it is hoisted to the surface. The apron feeder, belt conveyor and crusher installations are uniform so that the units can be moved readily and used at successive locations as the excavation proceeds. This limits the amount of large machinery that has to be taken underground and requires a minimum of labor After primary crushing the rock can be efficiently moved by belt conveyors. The rock may be removed to the surface by hoisting, or by conveyor through an inclined entryway, or mixed with water and pumped.

Excavation is advanced in a generally circular pattern by blasting rings of long holes toward the slot 19 and drawing broken rock from drawpoints 24 starting with that drawpoint which underlies the slot. Mining is continued from either one or both sides of the slot which, of course, increases in size as mining proceeds until the cylindrical annulus is generally complete. The general layout of long-hole drilling is shown schematically in lfig. where the lines identified by numeral 30 indicate the general pattern of drill holes. An appropriate charge in each drill hole is detonated to break the rock, working initially from the circular haulageway 23 and then from drill drives 17A and 18A and finally from drill drives 17 and 18. This mining method is known variously as sublevel stoping, sublevel stoping with long holes or simply long-hole stoping. A general description of blast hole drilling is found in the Canadian Mining and Metallurgical Bulletin for Oct. 1953, pages 622-633.

Appropriate sumps 31 are provided as needed and sump pumps 32 remove unwanted water from the excavation. Fresh air is circulated from a downcast shaft, preferably the smaller man shaft 15, through the working places and thence to an upcast shaft, preferably the larger hoisting shaft 14.

It will be seen that the generally circular configuration of the excavation minimizes the distance over which broken rock must be moved between the bottom of the excavation and the bottom of the hoisting shaft. Similarly the length of accessways leading from the shaft to the working places is minimized. A maximum tonnage of rock can be excavated to create the greatest possible volume of space by mining from one or both sides'of one or more slots.

The long-hole drilling method of mining is utilized so as to minimize the amount of preproduction work and the distance through which rock, supplies, equipment and men must be moved while maintaining high standards of safety, ventilation and efficiency. Excavation is accomplished with a minimum of undercutting, raising and other preparation. The excavation is sufficiently stable that use can be made of the space, as well as of the rock produced. Preproduction time and costs are minimized and ultimate costs of producing rock and space are minimized. The excavation system is adaptable to a range of moderate and high rate of production. Because access can be provided through shafts bored and cased from the surface, the excavation is readily adaptable to fast low-cost production of stone or rock from a mass of strong rock which does not appear at the surface but is covered by marsh or even shallow water, by weak or saturated strata or other cover through which the sinking and operation of conventional shafts is slow, costly or hazardous. Large volumes of low-cost stone can be produced at many convenient locations without any appreciable permanent change of surface topography without preempting any large area of the surface even during production. Even though the excavation is intended to be made in strong compact tight rock, the system is adaptable to use in many localities where rock is less than ideal in these respects.

As best seen in FIGS. 8 and 9, after one unit excavation has been nearly completed, the accessways which have been provided for the first may be used for a second unit or a number of successive similar units. The first stope, indicated generally at 33, is nearly completed except for a pillar 34 which is left in place until the second stope, indicated generally at 35, is complete. The slot raise 36 in the second excavation is located on the far side, as indicated. An interconnecting accessway 37 is provided for circulation of fresh air to the second excavation and a passage 38 is provided to exhaust air. An interconnecting haulageway 39 is provided for removing rock from the second excavation to the bottom of the hoisting shaft 14 of the first excavation.

Alternatively for excavations of lesser height, several concentric toroids may be executed to get the required volume. This may be done by extending the radial accessways and haulageways, in which event a pillar is left unexcavated in the first stope until the second stope is completed. Or better, a second toroid is excavated inside the first. This becomes more practicable as the height is reduced because, to be in good proportion, the pillar between the concentric excavations would not have to be so thick.

Some uses of the underground toroid space, such as disposal of solid wastes, are compatible with continued mining. In such cases, one completed segment of the toroid is put to use while excavation of other segments continues. Where separation is needed, mining can be stopped at any point of circumference, a vertical pillar left and mining resumed beyond a new slot.

A typical 10,000,000 ton toroid of the general configuration shown in FIGS. 1 through 4, may have an outside diameter of about 950 feet, a height of about 375 feet and a maximum thickness of about I40 feet. The top drill level is about feet from the top of the excavation. The middrill level is about 165 feet below the top drill level and about feet above the haulage level. The core of the annular excavation has a diameter of about 675 feet sufficient to support a substantial part of the stress increment which results from the excavation.

The embodiments of the invention in which we claim an exclusive property or privilege are defined as follows:

1. A system of excavation deep in the'earth which comprises the steps of:

A. providing an entranceway at least to the lowermost level of the excavation,

B. providing a shaft lying generally near the vertical axis of the excavation,

C. developing haulageways extending generally radially from said shaft adjacent the bottom of the excavation,

D. providing a rock-loading station at the bottom of said en tranceway,

E. developing at least one generally circular drill drive around but spaced from said shaft and accessible from said shaft,

F. developing at least one vertical slot raise from said drill drive and connecting with one of said haulageways,

G. blasting rings of long holes toward said slot and drawing the resulting broken rock from the haulageway from the bottom of said slot, and

H. advancing the excavation in a generally circular pattern by continued blasting and withdrawal of rock to form a toroidal excavation spaced from sand surrounding said axis.

2. A system according to claim 1 further characterized in that said entranceway includes a first shaft utilized as a hoisting shaft and a second smaller diameter man shaft is sunk generally parallel to the first and spaced therefrom.

3. A system according to claim 2 further characterized in that air is forced down said smaller shaft past working places on each level and returned to the surface through said hoisting shaft.

4. A system according to claim 1 further characterized in that a haulageway is developed at the bottom of the excavation connecting with the generally radial haulageways and extending in a generally circular ring around but spaced from said shaft.

5. A system according to claim 4 further characterized in that a pair of concentric circular inner and outer drill drives are developed at each drill level, each connected by generally radial accessways to said shaft, said accessways being spaced upwardly from said haulageways.

6. A system according to claim 5 further characterized in that at least two vertically spaced apart drill levels are established.

7. A system according to claim 5 further characterized in that passways are developed from said accessways to the loading station for removal of rock from preparatory workings.

8. A system according to claim 1 further characterized in that crushing means are provided in said haulageways adjacent the production area for subsurface crushing of rock before delivery to said loading point.

9. A system according to claim 1 further characterized in that the excavation is advanced by progressively drilling and blasting on both .sides of said slot.

10. A system according to claim 1 further characterized in that upon substantial completion of the excavation:

A. interconnecting accessways and haulageways are prepared extending from the first excavation to a nearby site for a second excavation,

B. accessways, drill drives and haulageways are developed for said second excavation,

C. at least one vertical slot raise is developed from said drill drives and connecting with one of said haulageways of said second excavation, and

D. excavation of the second excavation is advanced by progressively drilling and blasting adjacent said slot, drawing the broken rock from the bottom of the slot through the haulageways to the loading station at the bottom of the first excavation.

11. A system according to claim 10 further characterized in that said second excavation is formed concentric with the first excavation.

Claims

1. A system of excavation deep in the earth which comprises the steps of: A. providing an entranceway at least to the lowermost level of the excavation, B. providing a shaft lying generally near the vertical axis of the excavation, C. developing haulageways extending generally radially from said shaft adjacent the bottom of the excavation, D. providing a rock-loading station at the bottom of said entranceway, E. developing at least one generally circular drill drive around but spaced from said shaft and accessible from said shaft, F. developing at least one vertical slot raise from said drill drive and connecting with one of said haulageways, G. blasting rings of long holes toward said slot and drawing the resulting broken rock from the haulageway from the bottom of said slot, and H. advancing the excavation in a generally circular pattern by continued blasting and withdrawal of rock to form a toroidal excavation spaced from sand surrounding said axis.

9. A system according to claim 1 further characterized in that the excavation is advanced by progressively drilling and blasting on both sides of said slot.

10. A system according to claim 1 further characterized in that upon substantial completion of the excavation: A. interconnecting accessways and haulageways are prepared extending from the first excavation to a nearby site for a second excavation, B. accessways, drill drives and haulageways are developed for said second excavation, C. at least one vertical slot raise is developed from said drill drives and connecting with one of said haulageways of said second excavation, and D. excavation of the second excavation is advanced by progressively drilling and blasting adjacent said slot, drawing the broken rock from the bottom of the slot through the haulageways to the loading station at the bottom of the first excavation.