WO2007081216A1

WO2007081216A1 - Method and system for venting tunnels; mine galleries or the like

Info

Publication number: WO2007081216A1
Application number: PCT/NO2006/000476
Authority: WO
Inventors: Bo Johansson
Original assignee: Protan A/S
Priority date: 2006-01-10
Filing date: 2006-12-11
Publication date: 2007-07-19
Also published as: NO324914B1; NO20060137L

Abstract

The invention relates to a method and a system for supplying fresh air to a working face (17) in a tunnel (10) or in a mine gallery, where the fresh air in a controlled manner is supplied to a point (A, B) inside the tunnel (10) or the mine gallery, situated in close vicinity of the working face (17) . According to the invention, one end of a flexible duct (19) is connected to a point (A) for supply of fresh air, that the flexible duct (19) is movably suspended from a rail (18), wire or the like by means of suitable suspension means (20,21), where said flexible duct (19) may be pull forward or backward along said rail (18) wire or the like between a more or less retracted position and an extended position where the end of the flexible duct (19) are positioned near up to the working face.

Description

METHOD AND SYSTEM FOR VENTING TUNNELS; MINE GALLERIES OR THE LIKE .

The present invention relates to a method and a system for venting out dangerous gases and dust resulting from blasting of explosives in a tunnel or a mine gallery, comprising supply of fresh air in a controlled manner to a point inside the tunnel or the mine gallery, said point being placed at a predetermined distance from the actual blasting area.

When blasting explosives in tunnels and mine galleries poisonous gases and dust are produces in connection with detonation of explosives used. The poisonous gases and the dust must accordingly be vented out prior to allowing personnel to enter the area for removal of excavated rock and stones and to proceed with the drilling operations, etc. The time taken before the gases is vented out is thus a critical factor for the production and is a costly factor when excavating tunnels or mine galleries.

Up till now, the problem encountered is that the ducts blowing fresh air into the tunnel end at a distance of approximately 30-50 meters from the area of blasting. Hence it takes long time and is laborious to remove all the poisonous gases. The reason for ending the duct so far away from the area of blasting, is that the duct may damaged by rocks and stones from the' blasting, if the duct is terminated too closed to the blasting area.

An object of the invention is to improve the working environment for the operators working at or in the close vicinity of the blasting region,

Another object of the present invention is to make the excavation of tunnels more cost efficient.

A further object of the present invention is to enhance the blasting operation more efficiently and rationally. A still further object of the present invention is to provide a solution eliminating or at least greatly reducing the risk for causing damage to the existing, already installed safety and ventilation equipment inside the tunnel in the vicinity of the working face.

The objects of the invention are achieved by means of a method and a system as further defined by the characterizing parts of the independent claims, when read in conjunction with the preamble of the corresponding independent claims.

Features defined by the dependent claims. will also contribute to one or more of the objects achieved by the invention.

According to the present invention it is possible to quickly and efficiently remove poisonous gases at the working face, caused by the explosives used during blasting. Hence, a more rational and efficient operation of the blasting work in a tunnel is obtained.

Since fresh air more or less continuously is introduced into the working face, the working environment . for the operators inside the tunnel is enhanced, both during the drilling operations and subsequent to a blast. Thus, the operators are not exposed to unnecessary gasses and dust from the drilling and blasting operations. Another advantage according to the present invention ^• is that the already installed duct -system etc. for removing poisonous gases and dust, and for supply of fresh air to the working face, is not exposed to any real risk for being damaged due to the pressure from the explosion or from flying rocks or stones from the blasting.

A preferred embodiment of the invention will now be described in further detail, referring to the accompanying drawings, wherein.

Figure 1 shows schematically a longitudinal section of the inner end of a tunnel provided with a duct for supplying fresh air; Figure 2 shows schematically a longitudinal section of the part of the tunnel, shown in Figure 1_/ the flexible duct according to the invention being arranged in the space between the air supply duct and the excavation area. . Figure 3 shows schematically a corresponding longitudinal section shown in Figure 2, showing the means for^" retraction of a flexible duct to the working face in assembled and installed state, the duct being installed between the point of fresh air supply and the end of the previously installed flexible duct;

Figure 4 shows schematically a phase just prior to retraction of the flexible duct, prior to blasting;

Figure 5 shows schematically the phase subsequent to the flexible duct being retracted to its protected position, but still prior to blasting;

Figure 6 shows schematically the phase just after blasting of the explosives, but prior to completely extension of the flexible duct back to the excavation area; Figure 7 shows schematically the stage where the flexible duct is completely extended and where fresh air is supplied to said excavation area in order to remove dangerous gases and dust; and

Figure 8 shows schematically a view, partly in section, through the means for releasing the flexible duct from a retracted position prior to blasting to a position where the end of the duct is completely .extended to the recently blasted working face.

Figure 1 shows schematically a view of the first stage of establishing solution according to the invention inside a tunnel 10. An air supply duct 11, which for example extends from the area outside the tunnel 10, is suspended from the roof 12 of the tunnel 10. The duct 11 may for example be suspended from a suspension wire or a rail 13, fixed to the tunnel roof by means of a number of bolts 14. The duct 11 is suspended from the wire or the rail 13 by means of a plurality of hooks 15. The air supply duct 10 ends in an air supply zone 16 where the air leaves the duct 11 and is supplied to interior of the tunnel 10. As a part of the present invention, a wire or a rail 18 is suspended from the roof 12 of the tunnel 10 from the air supply zone 16 to the excavation zone 17. One end of the wire 18 may for example be attached to the roof at a point A, representing the inner suspension point for the wire or the rail 13 to which the air supply duct is suspended from. The opposite end of the wire or the rail

18 is attached to a point B, being located close to the zone of excavation 17. The wire is at the points A, B attached to the roof 12 of the tunnel by means of ■ conventional bolts or the like, for example bolts corresponding to the bolts 14.

Figure^' 2 shows the next stage in installation of the . solution according to the invention. Here a flexible duct

19 is stretched out in its entire length and suspended from the tensioned wire 18 by means of hooks 20 provided with pulleys 21 attached to the upper end of the hook 20. The pulley 21 runs more or less friction free on the wire or the rail 18. This detail of the suspension is shown in enlarged scale in Figure 2. In order to secure that the pulley 21 is not derailed off the wire 18, the pulley may preferably be equipped, with a groove or the like.

Figure 3 shows schematically a longitudinal section through the tunnel 10 shown in Figure 2, where the flexible duct is completely stretched out in its entire length. The only major difference with respect to the stage shown in Figure 2 is that at the point A, the connection area for the attachment of the flexible duct 19 to the air supply duct 12, a particularly designed drum 22 incorporating spring loaded retraction means (not shown) is incorporated into the system. Such spring loaded retraction means may for example be of a type which in many ways may correspond to the retraction means employed in petrol stations for. air supply hoses used for filling air into pneumatic tires on cars or retraction means employed for retracting electrical cables into a vacuum cleaner. One end of a wire 23 is attached to the drum 22 and extends over a pulley, wheel or the like 24, arranged for example on the hook at the free end of the flexible duct 19.

During work at the excavation zone, prior to detonation of explosives, the duct 19 may for example be stretched completely out so that fresh air is supplied at the excavation, area. This stage is shown in Figure 3.

When drilling of the holes for the explosives is completed, and just before detonation, the flexible duct 19 is withdrawn, for example by means of a rope 25, attached to the free end of the flexible duct 19. This retraction may for example be performed by one of the operators in the tunnel. The first step in this stage is shown in Figure 4, while Figure 5 shows the stage where the duct 19 is completely withdrawn into a folded position at great distance away from the excavation area. At this stage the wire 23 is completely pulled out from the drum 22 and a full spring force is accumulated in the drum 22. The drum 22 is temporarily locked in this position. Figure 6 shows the first phase immediately after detonation of the explosives. As indicated in the Figure a locking mechanism 26,31,32,33 on the drum 27 is released and the flexible duct 19 is pulled out in the direction of the detonation zone for immediate supply of fresh air into the detonation zone. Figure 7 shows the stage where the duct 19 again is in its fully stretched position.

The spring force of the drum 22 may be released manually by means of a remotely controlled system or automatically. Figure 8 indicates schematically a preferred embodiment of a releasing mechanism 26 for automatic release of the accumulated spring force. _r

6

Figure 8 shows schematically a view in enlarged scale, partly in section, of a drum 22. The drum comprises a drum body 27 which is rotatably suspended on a frame (not shown) . One end of the wire 23 is, as shown, fixed to the drum body 27 by means of any suitable attachment means 28, such as a clamp or the like. The drum 27 rotates around a centrally arranged shaft 29. One end of a coil spring 30 is fixed to the shaft 29, while the opposite end of the, coil spring is fixed to the inner surface of the drum body 27. The attachment means for fixing the spring may be of any suitable type without deviating from the inventive idea. Inside the drum body 27 a cogged surface 31 co-operating with one end of an elbow shaped arm 32 is arranged, the elbow shaped arm being formed of to legs forming an angle with each other. Said arm 32 is, at the elbow part, rotatably supported on a shaft 32 attached to an end wall (not shown) on the drum body 27. The opposite . end of the elbow shaped arm 32 is attached to a plate 26 which more or less is perpendicularly arranged with respect to the expected direction of the air pressure generated by the explosion.

A hook shaped body 34, intended to cooperate with the elbow shaped arm 32 for temporarily locking the arm, is fixed to the wall 12 of the tunnel 10 in the vicinity of the drum 22.

The drum functions in the following way: Prior to detonation of the explosives, the flexible duct 19- is completely withdrawn to a completely folded position at the end of the air supply duct 11. During this retraction movement the wire 23 is pulled in the direction II, whereby the drum 23 is rotated anti-clockwise. The wire 23 is then wound up on the drum body 27. As a result of this rotation the spring will be completely tensioned. In this position the shortest arm on the elbow shaped arm 32 is in locking engagement with the cogged surface 32 in the interior of the drum body 27. When the air pressure generated by the blasting of the explosives hits the plate 26, said pressure hitting the plate 26 causes a rotation of the arm 32 around the shaft 33, so that it is released from engagement with cogged surface 31. The spring force in the tensioned coil' spring 29. is then released, and the wire 23 is pulled .in direction I out from the drum 27. During this movement, the drum 27 rotates in a clockwise direction.

In order to maintain the rotation of the drum subsequent to the disappearance of the pressure, the longest part of the elbow shaped arm 32 is locked by the hook 34.

In this way the flexible duct 19 is automatically pulled out- in its entire length towards the working face, as a result of the blasting.

Hence, fresh air is supplied directly to the excavation area and fresh air is mixed with the poisonous gasses produced by the blasted explosives, thereby venting the poisonous gases out of the tunnel immediately after the blasting. The removal work of blasted rock 27 in the excavation area may thus start earlier than experienced for prior art solutions, where it was necessary to wait ■ for a longer period until the poisonous gases had been vented out. Another important advantage is that fresh air also is supplied to the excavation area during the preparation phase where the holes are drilled and rock dust is produced by the drilling operations.

According to the disclosed embodiment a release mechanism released by the pressure wave from the explosion is used. It should be appreciated, however, the release ^■ may be remotely controlled without deviating from the inventive idea.

Further, it should be appreciated that the drum 22 may be of a type where the folded flexible duct, when released by the accumulated spring force, is pulled out towards the excavation area.

According to a preferred embodiment of the invention the air supply duct and the flexible hose are suspended from the roof of the tunnel. It should be- appreciated, however, hat the air supply duct and the flexible duct maybe suspended from the wall of the tunnel. In such case the only the suspension means employed requires modification. Such modification is of a type which would be obvious for the person skilled in the art.

Claims

C l a i m s

1. Method for supplying fresh air to a working face (17) in a tunnel (10) or a mine gallery, where the fresh air in a controlled manner is supplied to a point (A, B) inside the tunnel (10) or the mine gallery, said points being in close vicinity of the working face (17), c h a r a c t e r i z e d i n that one end of a flexible duct (19) is connected to a point (A) for supply of fresh air, that the flexible duct (19) is movably suspended from a rail (18), wire or the like by means of suitable suspension means (20,21), where said flexible duct (19) may be pull forward or backward along said rail

(18) wire or the like between a more or less retracted position and an extended position where the end of the flexible duct (19) are positioned near up to the working face (17).

2. Method according to claim 1, wherein said rail (18), ^■ wire or the like firstly are preferably fixed to the roof

(12) of the tunnel (10) or the mine gallery, that the flexible duct (19) then is suspended from said rail (18) , wire or the like and is connected to the air supply point

(A) , whereupon the flexible duct (19) is extended to the working face (17) .

3. Method according to claim 1 or 2, wherein the duct

(19) is retracted at least partly towards the air supply point (A) prior to detonation of the explosives, whereupon the duct (19) is pulled out again towards the working face (17) at upon completed detonation.

4. Method according to one of the claims 1-3, where the extension operation of the duct (19) towards the working face (17) is achieved by means of a spring device (30) or the like, arranged in the region of the air supply point (A) where the duct (19) is connected to the air supply duct (11).

^■ 5. Method according to claim- 4, where release of the duct (19) from its retracted position is achieved by means of a release mechanism (26,31,32,33) which may be released by means of the air pressure caused by the blasting at the working face (17) .

6. Method according to claim 4, where the release of the spring mechanism (30) may be remotely controlled.

7. Method according to one of the claims 1-6, where air is supplied continuously to the working face (17) through the flexible duct (19) -

8. System for supply of fresh air to a working face (17) in a tunnel (10) or a mine gallery, where the fresh air in a controlled manner is supplied to a point (A, B) in the tunnel (10) or the mine gallery, positioned in the vicinity of the working face (17), c h a r a c t e r i z e d i n that a foldable flexible duct (19) is arranged between the point (A, B) for supply of fresh air and the working face (17), where the retractable duct (19) is configured to be retracted back towards the point (A) for supply of fresh air during the blasting and then be pulled out again towards the working face (17) immediately upon completed blasting.

9. System according to claim 8, where the duct (19) being slidably suspended on a wire (18) or a rail suspended from the roof (12) or the wall of the tunnel (10) .

10. System according to claim 9, where the duct (19) is supported by pulleys (21) in order to reduce the friction _{χ χ}

between the duct (19) and the wire (18) or the rail.

11. System according to one of the claims 7-10, where a second wire (23) or the like,' one end of which being attached to the free end of the duct (19), runs over a pulley (24) or the like, arranged in the area of blasting, and^'extending back to the air supply duct (11), the other end of the wire (23) being removably stored on a spring loaded drum (22) .

12. System according to claim 11, where the drum (22) is of a type where the spring force is accumulated to maximum when the duct (19) is in its completely retracted position and that the duct (19) will be pulled outwards towards the working face (17) when the spring mechanism is released.

13. System according to claim 12, where the drum (22) is provided with a releasing mechanism (26,32,33).

14. System according to claim 13, where the release mechanism (26,32,33) is configured in such way that the release mechanism (26,32,33) is released by the pressure produced by the blasting.

15. System according to claim 13, where the release mechanism (26,32,33) is configured in such way that • release of the spring force may be remotely controlled.