JP2013117364A - Duct device and dust collecting system within tunnel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a duct device capable of moving a tip opening of a duct sufficiently closer to a working face etc.SOLUTION: The duct device includes: the duct 10 suspended on a guide rail 7; and a moving mechanism 20 moving the tip opening 11A of the duct 10 forwardly/rearwardly. The duct 10 includes: a suspending part 12 in which the moving mechanism 20 is installed; and an extending part 11 extending forwardly from the suspending part 12. The moving mechanism 20 includes: a fulcrum member 21 mounted to the suspending part 12 and suspended on the guide rail 7; and a driving wheel 22 mounted to the suspending part 12 on the rear side of the fulcrum member 21. Due to the weight of the extending part 11, the driving wheel 22 is pressed on the guide rail 7 from the lower side by using the fulcrum member 21 as a fulcrum.

Description

  The present invention relates to a duct device that can be used as a suction duct or the like for sucking dust directly under a face in tunnel construction, and a dust collection system in a tunnel using the duct device.

  As a method for collecting dust generated in a tunnel or the like, for example, it can be roughly classified into an air supply dust collection method and an exhaust dust collection method, which are dilution containment methods, and a suction collection method. The former dilution containment method is a method in which air is sent (exhaust) toward the face and the dust is diluted. In order to increase the dilution effect, the air supply port is connected to the tunnel equivalent diameter from the face (reference numeral in FIG. 1). (D represents the tunnel equivalent diameter). On the other hand, the latter suction collection system has no such restriction, and conversely, it is necessary to increase the dust collection effect by bringing the suction port closer to the face.

  In this regard, in tunnel construction, dust is mainly generated directly under the face, so the latter suction collection method is said to be efficient. However, under the face, various operations such as ground drilling, charging, blasting, slipping, and concrete spraying are performed. Therefore, it is preferable to use a dust collection system using an extendable duct that can move the suction port closer to or away from the face so as not to hinder these operations (see, for example, Patent Documents 1 and 2). .)

  In this dust collection system, for example, as shown in FIG. 8, a dust collector 105 is loaded on a moving means such as a truck or a sled carriage, in the illustrated example, a truck 106 and carried into a tunnel T. In a state where the dust collector 105 is loaded on the truck 106, a duct (wind pipe) 101 is connected to a suction port thereof, and a tip opening 101A of the duct 101 serves as a suction port. The duct 101 has a stretchable portion 102 that can be stretched in the front-rear direction. Therefore, when the expansion / contraction part 102 expands / contracts, the front end opening (suction port) 101A of the duct 101 moves back and forth, and approaches or moves away from the facet surface Ty. The duct 101 is suspended from the guide rail 7, and the guide rail 7 is laid on the side wall of the tunnel T, the ceiling Tx, and the like, for example.

  In this dust collection system, for example, a rack-and-pinion system in which a pinion as a gear rolls on the rack with the guide rail 7 as a rack is used as a moving mechanism that expands and contracts the expansion / contraction part 102 and moves forward and backward. There is a crane trolley system or the like in which the guide rail 7 is used as a garter and the wheels roll on the garter. In this regard, as described above, in the suction collection system, it is important to suck the dust generated immediately below the face before it is diffused and diluted. If the tip opening (suction port) 101A is brought close to the face face Ty and sucked, it is important. Increases dust collection efficiency. Therefore, at the time of blasting work, in order to avoid damage to the duct 101 due to rock scattering or the like, the tip opening 101A of the duct 101 is separated from the face Ty by, for example, 50 m or more, and then when performing the suction work, The tip opening 101A is moved toward the face surface Ty using the moving mechanism.

  However, the guide rail 7 may also be damaged due to scattering of rocks. Further, it is necessary to avoid the guide rail 7 from coming into contact with a device for performing the various operations, for example, an excavator, a sprayer, an erector and the like, just below the face. Therefore, the tip 7A of the guide rail 7 needs to be separated from the face surface Ty by about 20 m. Further, there are cases where the ground is drilled using a free section excavator or the like without using blasting, but from the viewpoint of preventing contact with the excavator, the tip portion 7A of the guide rail 7 has a face. It is necessary to separate about 15 m from the surface Ty.

  As described above, in tunnel construction, there is a restriction that the front end portion 7A of the guide rail 7 cannot be sufficiently close to the facet surface Ty, and as a result, the front end opening 101A of the duct 101 is approximately the same as the facet surface Ty. I will leave. Therefore, there is room for further improvement in terms of increasing dust collection efficiency. Further, even if the distal end portion 7A of the guide rail 7 is separated from the face surface Ty by about 15 to 20 m, pebbles may ride on the guide rail 7 and the above-described pinion and wheel biting troubles may occur. . When such a biting trouble or the like occurs, a sufficient torque is not applied to the pinion, the wheel, and the like, so that the moving speed of the tip opening 101A becomes slow, and in some cases, there is a possibility that the moving becomes impossible. When the moving speed is slow, the time until the tip opening 101A approaches the face surface Ty becomes long, and dust is diffused and diluted during that time, and the dust collection efficiency is lowered. Therefore, a decrease in moving speed is also a big problem.

JP 2004-116793 A JP 2010-32168 A

  The main problem to be solved by the present invention is to provide a duct device that can sufficiently bring the front end opening of the duct close to the face face and the like, and a dust collection system in the tunnel that is excellent in dust collection efficiency.

The present invention that has solved this problem is as follows.
[Invention of Claim 1]
A duct device having a duct suspended on a guide rail and a moving mechanism for moving the front end opening of the duct back and forth,
The duct has a suspension part provided with the moving mechanism, and an extension part extending forward from the suspension part,
The moving mechanism has a fulcrum member attached to the suspension part and suspended on the guide rail, and a drive wheel attached to the suspension part behind the fulcrum member,
The driving wheel is configured to be pressed against the guide rail from below by using the fulcrum member as a fulcrum by the weight of the extending portion.
A duct device characterized by that.

(Main effects)
Even if the tip of the guide rail cannot be brought close to the face, etc., if the duct is extended to the tip of the guide rail (overhang), the end of the duct can be brought close to the face. it can. However, for example, as shown in FIG. 7, when the distal end portion of the duct 101 is extended, the driving wheel 104 such as a pinion or a wheel that rolls on the guide rail 7 due to the weight of the extending portion (overhang portion) 103 is provided. It will float up and it will not be possible to secure a sufficient driving force. In addition, the possibility that pebbles or the like ride on the guide rails 7 and cause troubles of the drive wheels 104 is not solved.
On the other hand, for example, as shown in FIG. 6, the duct 10 includes a suspension part 12 provided with a moving mechanism 20 and an extension part (overhang part) 11 extending forward from the suspension part 12. The mechanism 20 is attached to the suspension part 12 and includes a fulcrum member 21 made of a bearing or the like suspended from the guide rail 7, and a drive wheel 22 made of a tire attached to the suspension part 12 behind the fulcrum member 21. And the driving wheel 22 is pressed against the guide rail 7 from below by using the fulcrum member 21 as a fulcrum by the weight of the extending portion 11, a sufficient torque is applied to the driving wheel 22. It can be secured sufficiently, and the front end opening of the duct 11 can be moved back and forth reliably and quickly. Of course, since the extension part 11 of the duct 10 extends ahead of the guide rail front end part 7A, the front end opening of the duct 10 can be made sufficiently close to the face surface or the like. In addition, since the drive wheels 22 are pressed against the guide rail 7 from below, even if pebbles or the like ride on the guide rail 7, there is no possibility that a biting trouble will occur. Note that the fulcrum member 21 is not a member for securing the driving force, and there is no possibility that the driving force is lost due to the biting of pebbles or the like.

[Invention of Claim 2]
An upper restraining member attached to the suspension part behind the drive wheel and located above the guide rail;
A lower restraining member attached to the suspension portion behind the driving wheel and positioned below the guide rail,
The duct apparatus according to claim 1.

(Main effects)
For example, as shown in FIG. 6, the upper restraining member 23 </ b> A is attached to the suspension portion 12 at the rear of the drive wheel 22 and is located above the guide rail 7, and is attached to the suspension portion 12 at the rear of the drive wheel 22, In addition, when the lower restraining member 23 </ b> B located below the guide rail 7 is provided, the vertical movement of the duct 10 during the back-and-forth movement is suppressed, and torque is reliably applied to the drive wheels 22. Further, in the state where the duct 10 is moved forward, even if the extension portion 11 is damaged or the like and the weight of the extension portion 11 is reduced, the driving wheel 22 is caused by the presence of the upper restraining member 23A. Since it is prevented from falling downward, the torque applied to the drive wheel 22 is not completely lost, and the duct 10 can be returned to the rear.

[Invention of Claim 3]
The extending portion has a circular arc-shaped wall material composed of at least one of a polycarbonate sheet and a plastic corrugated sheet, and is connected in the circumferential direction to have a cylindrical shape.
The duct apparatus according to claim 1 or 2.

(Main effects)
Polycarbonate is a material, and a plastic corrugated sheet is a material that is lightweight but has sufficient strength. Therefore, when the wall material of the extension part is formed by these sheets, the whole extension part becomes light and it is possible to ensure a long extension length.
Further, when the wall material made of the sheet has an arc-shaped cross section and is connected in the circumferential direction to form a cylindrical extension portion, a plurality of wall materials are overlapped in a vertical direction, a track or the like Since it can be loaded into the tunnel, it becomes very easy to carry it into the tunnel.

[Invention of Claim 4]
A guide rail laid on the inner wall surface of the tunnel, a duct suspended on the guide rail, and a moving mechanism for moving the front end opening of the duct back and forth,
A dust collection system in the tunnel for sucking dust immediately below the face of the tunnel from the opening of the end of the duct,
The duct has a suspension part provided with the moving mechanism, and an extension part extending forward from the suspension part,
The moving mechanism has a fulcrum member attached to the suspension part and suspended on the guide rail, and a drive wheel attached to the suspension part behind the fulcrum member,
The driving wheel is configured to be pressed against the guide rail from below by using the fulcrum member as a fulcrum by the weight of the extending portion.
A dust collection system in a tunnel.

(Main effects)
As is apparent from the function and effect of the first aspect of the present invention, according to the present invention, the front end opening of the duct can be brought close enough to the face surface, so that dust can be sucked before being diffused and diluted. It becomes a dust collection system in a tunnel with excellent efficiency.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes a duct apparatus which can fully approach the front-end | tip opening of a duct to a face face etc., and the dust collection system in the tunnel excellent in dust collection efficiency.

It is a side surface conceptual diagram of the dust collection system of this form. It is a front conceptual diagram of the dust collection system of this form. It is a side block diagram of the moving mechanism of this form. It is a cross-sectional conceptual diagram of the moving mechanism of this form. It is an example of the form of the duct extension part of this form. It is a conceptual explanatory drawing of the moving mechanism of this form. It is a conceptual explanatory drawing of the moving mechanism which does not depend on this form. It is a side surface conceptual diagram of the conventional dust collection system.

Next, the form for implementing this invention is demonstrated.
1 and 2 show the dust collection system of this embodiment. The dust collection system of this embodiment is a suction collection system, and is good at collecting dust (collecting) dust generated just below the face (face face Ty) in the tunnel T.

  In the dust collection system of this embodiment, the guide rail 7 is laid on the ceiling Tx of the tunnel T. The guide rail 7 is provided along the axial direction of the tunnel T. The guide rail 7 is suspended by a plurality of suspension tools (anchors) 8 fixed to the ceiling Tx at an appropriate interval. For example, as shown in FIGS. 4 (1) to (3), the guide rail 7 is formed of an H-section steel having a web 7A and upper and lower flanges 7B and 7C connected to both ends of the web 7A. Yes. Since the guide rail 7 is formed of H-shaped steel, repair, replacement, etc. when the guide rail 7 is damaged can be easily performed, and can be performed at low cost.

  In the tunnel T, the dust collector 105 is loaded (mounted) on the truck 106 and carried in. The carried-in dust collector 105 is used while being loaded on the truck 106. The dust collector 105 is arranged so that the suction port faces the face Ty side of the tunnel T and the exhaust port 105A faces a tunnel (not shown) of the tunnel T.

  A duct (wind pipe) 10 is connected to the suction port of the dust collector 105. The duct 10 is, for example, cylindrical. The duct 10 includes a connecting portion 15, a fixed length portion 14, a telescopic portion 13, a suspension portion 12, and an extension portion (overhang portion) 11 in order from the dust collector 105 side.

  The connection part 15 is a duct for connecting the suction port of the dust collector 105 located on the bottom part (bottom face Tz side) of the tunnel T and the fixed long part 14 etc. located on the top part (ceiling Tx side) of the tunnel T. . The connecting portion 15 may or may not expand and contract in the axial direction. On the other hand, the fixed length portion 14 is a fixed length duct that does not expand and contract in the front-rear direction. The fixed length portion 14 is suspended from the guide rail 7 as necessary. However, the fixed length portion 14 may be omitted and the connection portion 15 and the extendable portion 13 may be directly connected. The stretchable part 13 is a duct that can be stretched in the front-rear direction (axial direction) using a bellows structure or the like. The telescopic part 13 is suspended from the guide rail 7 as necessary. The suspension 12 is a fixed-length duct that does not expand and contract in the front-rear direction. The suspension part 12 is suspended by the guide rail 7 using the moving mechanism 20 (refer FIG. 3). The extending portion 11 extending forward from the suspension portion 12 is also a fixed-length duct that does not expand and contract in the front-rear direction. However, the extending portion 11 is configured not to be suspended from the guide rail 7 but to extend beyond the tip end portion 7A of the guide rail 7. Therefore, the front end opening (suction port) 11A of the duct 10 constituted by the front end opening of the extending part 11 can be moved forward and brought close to the face surface Ty.

  The movement of the tip opening 11 </ b> A is performed by a moving mechanism 20 attached to the suspension portion 12. As shown in FIG. 3, the moving mechanism 20 includes a vertical bearing 41 as a support member, a no-puncture tire 42 as a drive wheel, an upper vertical bearing 43A as an upper restraining member, and a lower vertical bearing 43B as a lower restraining member, It consists of

  The vertical bearing 41 is attached to the suspension portion 12 and suspended from the guide rail 7. More specifically, first, as shown in FIG. 4A, the vertical bearing 41 rolls on the upper plane 7Ca of the lower flange 7C constituting the guide rail 7 with the width direction of the tunnel T as the rotation axis direction. It is configured. Further, the rotary shaft of the vertical bearing 41 is pivotally supported by a support member 51 as shown in FIG. And the support material 51 is being fixed to the top part of the suspension part 12 with the volt | bolt 51v. In this way, the vertical bearing 41 is attached to the suspension portion 12 and is suspended from the guide rail 7.

  Two vertical bearings 41 of this embodiment are provided, one on each side of the web 7 </ b> A constituting the guide rail 7. However, only one vertical bearing 41 may be provided, or a plurality of three or more vertical bearings 41 may be provided. Further, along with the vertical bearing 41, as shown by a two-dot chain line in the figure, a horizontal bearing 41X or the like that rolls along the both ends of the lower flange 7C with the vertical direction as the rotational axis direction may be provided.

  On the other hand, the no-puncture tire 42 is attached to the suspension portion 12 behind the vertical bearing 41 and can be driven to rotate. More specifically, first, as shown in FIG. 4B, the no-bank tire 42 rolls on the lower plane 7Cb of the lower flange 7C with the width direction of the tunnel T as the rotation axis direction, that is, frictionally travels. It is configured as follows. Further, as illustrated in FIG. 3, the rotation shaft of the no-puncture tire 42 is connected to the drive shaft of a drive mechanism provided with a motor 52M and the like so as to be rotatable. The drive mechanism is fixed to the top of the suspension 12 in the suspension 12. In this way, the no-puncture tire 42 is attached to the suspension portion 12 and can be driven to rotate. In addition, the opening 52 is formed in the top part of the suspension part 12, and when the no-puncture tire 42 protrudes upward from the said opening 52, the upper end part of the no-puncture tire 42 is on the lower plane 7Cb of the lower flange 7C. It is comprised so that it may contact | abut. Moreover, normal tires other than the no-bank tire 42 can also be used.

  The upper vertical bearing 43 </ b> A is attached to the suspension portion 12 behind the no-puncture tire 42, and is positioned above the lower flange 7 </ b> C constituting the guide rail 7. Regarding the upper meaning, the upper vertical bearing 43A is not located above the web 7A or the upper flange 7B constituting the guide rail 7, but because of its structure, the upper direction of the guide rail 7 here refers to It will be apparent that it is above the lower flange 7C constituting the guide rail 7. On the other hand, the lower vertical bearing 43 </ b> B is attached to the suspension portion 12 behind the no-puncture tire 42 and is positioned below the lower flange 7 </ b> C constituting the guide rail 7.

  The above will be described in more detail. First, as shown in FIG. 4 (3), the upper vertical bearing 43A has an upper plane 7Ca of the lower flange 7C constituting the guide rail 7 with the width direction of the tunnel T as the rotation axis direction. It is configured to roll up. Further, the rotating shaft of the upper vertical bearing 43A is pivotally supported by a support member 53 as shown in FIG. And the support material 53 is being fixed to the top part of the suspension part 12 with the volt | bolt 53v. In this way, the upper vertical bearing 43A is attached to the suspension portion 12 and is positioned above the lower flange 7C. Similarly, as shown in FIG. 4 (3), the lower vertical bearing 43B rolls on the lower plane 7Cb of the lower flange 7C constituting the guide rail 7 with the width direction of the tunnel T as the rotation axis direction. It is configured. Further, the rotating shaft of the lower vertical bearing 43B is pivotally supported by a support member 53 as shown in FIG. And the support material 53 is being fixed to the top part of the suspension part 12 with the volt | bolt 53v. In this way, the lower vertical bearing 43B is attached to the suspension portion 12 and is positioned below the lower flange 7C.

  Two upper vertical bearings 43 </ b> A of this embodiment are provided, one on each side of the web 7 </ b> A constituting the guide rail 7. However, only one upper vertical bearing 43A may be provided, or a plurality of three or more upper bearings may be provided. Similarly, a total of two lower vertical bearings 43B are provided to face the pair of upper vertical bearings 43A across the lower flange 7C constituting the guide rail 7. However, only one lower longitudinal bearing 43B may be provided, or a plurality of three or more lower bearings may be provided. Further, the upper vertical bearing 43A and the lower vertical bearing 43B may or may not be in contact with the lower flange 7C, but are preferably in contact as described later.

  According to the dust collection system of the present embodiment described above, the no-puncture tire 42 is pressed from below onto the lower flange 7 </ b> C constituting the guide rail 7 with the vertical bearing 41 as a fulcrum member serving as a fulcrum due to the weight of the extending portion 11. Accordingly, a sufficient torque is applied to the no-puncture tire 42 and a sufficient frictional force is obtained with the lower flange 7C, so that the front end opening 11A of the duct 11 can be moved back and forth reliably and quickly. In addition, since the no-puncture tire 42 is pressed against the lower flange 7C from below, even if pebbles or the like ride on the lower flange 7C, there is no possibility of causing a biting trouble or the like, and the driving force may be reduced. Absent. Note that the vertical bearings 41, 43A, 43B and the like are not members for securing the driving force, and there is no possibility that the driving force is reduced or lost by biting of pebbles or the like.

  Further, according to the dust collection system of this embodiment, the vertical bearings 43 </ b> A and 43 </ b> B suppress vertical deflection when the duct 10 moves back and forth, and torque is reliably applied to the no-puncture tire 42. In this regard, as described above, the bearings 43A and 43B may or may not be in contact with the lower flange 7C. However, the contact makes it possible to more reliably suppress the vertical runout of the no-puncture tire 42 and the like. Can do. In particular, when they are in contact, the use of bearings as the upper restraining member and the lower restraining member as in the present embodiment can reduce the movement resistance, for example, improving the moving speed and the like. it can. The same applies to the vertical bearing 41 serving as a fulcrum member. Since the vertical bearing 41 is in contact with the lower flange 7C, the movement resistance is reduced by employing the bearing.

  Moreover, in the dust collection system of this form, even if the extension part 11 is damaged and lightened in a state where the extension part 11 extends forward, the presence of the upper vertical bearing 43A causes no puncture tires. 42 is prevented from falling downward. Therefore, the torque of the no-puncture tire 42 is not lost, and the duct 10 can be returned to the rear.

  As described above, the dust collection system of the present embodiment is extremely excellent. However, it is more preferable that the wall material of the extending portion 11 is formed of a polycarbonate (polycarbonate) sheet or a prada sheet. The polycarbonate sheet is a material, and the pladan sheet is a material having a sufficient strength while being lightweight in terms of structure. Therefore, the extension length can be made longer by forming the wall material of the extension part 11 with these materials.

  In the prototype of the present inventor, the weight of the extending portion (diameter 1.5 m, length 11 m) could be reduced to 150 kgf. In this prototype, the distance from the vertical bearing 41 to the no-puncture tire 42 was 90 cm, and the pressing force (push-up force) of the no-puncture tire 42 against the guide rail 7 was 917 kgf.

  Polycarbonate is a material having the highest strength among transparent plastics that are 150 times or more of tempered glass. The Pradan sheet is a corrugated cardboard sheet made of plastic, and has both light weight and high strength due to the structural characteristics of a hollow structure. As a material for the Pradan sheet, polycarbonate can be selected and used in addition to polypropylene.

  Here, it is preferable that the wall material made of a polycarbonate sheet or a pladan sheet has an arcuate cross section and is connected in the circumferential direction so that the cylindrical extension portion 11 is formed. According to this embodiment, as shown in (1) of FIG. 5, the capacity can be reduced by stacking the wall materials 11A in the same direction. Therefore, it becomes very easy to carry the extension part 11 into the tunnel T. In this respect, the wall material 11A carried into the tunnel T changes its direction so that each wall material 11A bulges outward as shown in FIG. 5 (2), and as shown in FIG. 5 (3). The wall materials 11A adjacent to each other can be connected to form a cylindrical shape. Although not particularly shown, the extending portion 11 can be configured by connecting a plurality of wall materials in the axial direction. In the figure, the hatched portion (hatched portion) indicates a portion where a polycarbonate sheet or a pladan sheet is used, and the surrounding portion indicates a frame for connection.

(Other)
Although the dust collection system of the present embodiment is a suction collection system, an air supply / suction collection system in which air supply is appropriately combined may be employed. Further, the duct 11 of this embodiment can be appropriately changed in strength according to the suction air volume and the like. The suction air volume is not determined by the amount of dust generated immediately below the face, but is determined based on the collection control wind speed (mine wind speed) necessary to contain the inside of the tunnel (in the mine) with fresh air.

  The duct device of the present invention is not only usable as a suction duct, but can also be used as an exhaust duct if necessary. Further, if it is necessary to overhang the duct, it can be applied to a place where such a need exists other than the tunnel construction site.

  INDUSTRIAL APPLICABILITY The present invention can be applied as a duct device that can be used as a suction duct or the like that sucks dust directly under a face in tunnel construction, and a dust collection system in a tunnel using this duct device.

  7 ... Guide rail, 7A ... Web, 7B ... Upper flange, 7C ... Lower flange, 8 ... Hang (anchor) 10,101 ... Duct, 11,103 ... Extension part (overhang part), 12 ... Suspension part , 13, 102 ... telescopic part, 14 ... fixed length part, 15 ... connection part, 20 ... moving mechanism, 21 ... fulcrum member, 22, 104 ... driving wheel, 23A ... upper restraint member, 23B ... lower restraint member, 41 43A, 43B ... vertical bearings, 41X ... horizontal bearings, 105 ... dust collector, 106 ... truck, T ... tunnel, Tx ... ceiling, Ty ... face, Tz ... bottom.

Claims (4)

A duct device having a duct suspended on a guide rail and a moving mechanism for moving the front end opening of the duct back and forth,
The duct has a suspension part provided with the moving mechanism, and an extension part extending forward from the suspension part,
The moving mechanism has a fulcrum member attached to the suspension part and suspended on the guide rail, and a drive wheel attached to the suspension part behind the fulcrum member,
The driving wheel is configured to be pressed against the guide rail from below by using the fulcrum member as a fulcrum by the weight of the extending portion.
A duct device characterized by that. An upper restraining member attached to the suspension part behind the drive wheel and located above the guide rail;
A lower restraining member attached to the suspension portion behind the driving wheel and positioned below the guide rail,
The duct apparatus according to claim 1. The extending portion has a circular arc-shaped wall material composed of at least one of a polycarbonate sheet and a plastic corrugated sheet, and is connected in the circumferential direction to have a cylindrical shape.
The duct apparatus according to claim 1 or 2. A guide rail laid on the inner wall surface of the tunnel, a duct suspended on the guide rail, and a moving mechanism for moving the front end opening of the duct back and forth,
A dust collection system in the tunnel for sucking dust immediately below the face of the tunnel from the opening of the end of the duct,
The duct has a suspension part provided with the moving mechanism, and an extension part extending forward from the suspension part,
The moving mechanism has a fulcrum member attached to the suspension part and suspended on the guide rail, and a drive wheel attached to the suspension part behind the fulcrum member,
The driving wheel is configured to be pressed against the guide rail from below by using the fulcrum member as a fulcrum by the weight of the extending portion.
A dust collection system in a tunnel.

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