Method for removing suspended dust after blasting of tunnel face

Abstract

To effectively remove suspended dust generated by blasting at a tunnel face.SOLUTION: The present invention is a method for removing suspended dust after blasting of a tunnel face by spraying charged water particles into a tunnel. After blasting, a dust diffusion prevention mode is performed in which the charged water particles are sprayed in the radial direction of the tunnel while moving toward a face S with the airflow from an air duct 1 stopped, and then a dust removal mode is performed in which the charged water particles are sprayed forward while moving toward the face S by starting the airflow from the air duct 1. The charged water particles are sprayed while moving a vehicle 3 equipped with a charged water particle spraying device 2 capable of switching the spray direction of the charged water particles, or the charged water particles are sprayed while making the charged water particle spraying device 2 capable of switching the spray direction of the charged water particles travel along a rail 21 extending in the tunnel axial direction.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for removing airborne dust generated by blasting at a tunnel face during tunnel construction. [Background technology]

[0002] During tunnel construction, blasting at the tunnel face generates large amounts of dust, which becomes suspended in the air inside the tunnel.

[0003] Conventionally, dust generated by blasting at the tunnel face was removed by blowing air from an air duct 50 and collecting the dust pushed back by the wind with a dust collector 51 installed at a position away from the face, as shown in Figure 10. Then, workers waited at a position away from the face until the dust concentration had sufficiently decreased, and only after confirming that the dust concentration had decreased to a level at which work could be carried out could they begin work such as removing debris.

[0004] However, this method had drawbacks, such as the time it took for the dust concentration to decrease, resulting in wasted work time, and the fact that dust was more likely to spread inside the tunnel if the dust collector's performance was lower than expected.

[0005] On the other hand, a method is known in which electrically charged water particles are sprayed into the air inside a tunnel, causing the charged water particles and dust to be electrically attracted to each other, and causing the dust to fall together with the charged water particles, thereby removing them from the air (see, for example, Patent Documents 1 and 2 below). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2018-16965 A [Patent Document 2] JP 2018-204346 A Summary of the Invention [Problem to be solved by the invention]

[0007] When excavating a tunnel face, the dust dispersion situation immediately after blasting is such that the dust concentration is high near the blasting position near the face, and the dust gradually diffuses away from the face, eventually spreading almost uniformly over the entire cross section of the tunnel.

[0008] In conventional methods for removing suspended dust using charged water particles, the spray direction of the charged water particles is almost constant, and therefore the method is not designed to efficiently remove dust according to its dispersion state.

[0009] Therefore, the main object of the present invention is to provide a method for removing airborne dust after blasting of a tunnel face, which can effectively remove airborne dust generated by blasting of the tunnel face. [Means for solving the problem]

[0010] In order to solve the above problems, the present invention according to claim 1 provides a method for removing suspended dust after blasting of a tunnel face by spraying electrostatically charged water particles into the tunnel shaft, A method for removing suspended dust after blasting at a tunnel face is provided, which is characterized by performing a dust diffusion prevention mode in which, after blasting, air blowing from the air duct is stopped and the charged water particles are sprayed in the radial direction of the tunnel while moving toward the face, and then performing a dust removal mode in which air blowing from the air duct is started and the charged water particles are sprayed in the forward direction while moving toward the face.

[0011] In the invention described in claim 1, first, after blasting the tunnel face, the air blowing from the wind pipe is stopped, and the dust diffusion prevention mode is performed in which the charged water particles are sprayed in the radial direction of the tunnel while moving toward the face. This dust diffusion prevention mode can prevent further diffusion of dust that has diffused from the face side and spread over the entire tunnel cross section after blasting the face.

[0012] Then, the blowing of air from the air duct is started, and the dust removal mode is performed in which the electrically charged water particles are sprayed forward while moving toward the tunnel face. This dust removal mode pushes back the dust diffusing into the tunnel from the face side to the face side, which is the source of the dust, narrowing the area with high dust concentration, and by spraying the electrically charged water particles there, the dust can be efficiently removed.

[0013] The present invention according to claim 2 provides a method for removing suspended dust after blasting at a tunnel face as described in claim 1, in which the charged water particles are sprayed while moving a vehicle or drone equipped with an charged water particle spraying device capable of switching the spray direction of the charged water particles.

[0014] In the invention described in claim 2 above, by mounting an electrically charged water particle spraying device that sprays electrically charged water particles on a vehicle or drone, it is possible to spray electrically charged water particles while moving toward the face.

[0015] The present invention as claimed in claim 3 provides a method for removing suspended dust after blasting of a tunnel face as described in claim 1, in which an electrically charged water particle spraying device capable of switching the spray direction of the electrically charged water particles is run along a rail extending in the tunnel axial direction while spraying the electrically charged water particles.

[0016] In the invention described in claim 3 above, the charged water particle spraying device that sprays charged water particles is made to run along a rail extending in the tunnel axial direction, making it possible to spray charged water particles while moving in the direction of the tunnel face.

[0017] As the present invention related to claim 4, there is provided a method for removing suspended dust after blasting at a tunnel face as described in either claim 2 or 3, in which the charged water particle spraying device comprises a fan with an adjustable blowing direction and a spray nozzle arranged near the fan's outlet for spraying the charged water particles toward the blown airflow.

[0018] As the present invention according to claim 5, there is provided a method for removing suspended dust after blasting at a tunnel face as described in either claim 2 or 3, in which the charged water particle spraying device comprises a tubular body and a plurality of spray nozzles for spraying the charged water particles, the spray nozzles being spaced apart in the axial direction of the tubular body.

[0019] The inventions described in claims 4 and 5 above show specific examples of preferred configurations of the electrically charged water particle spray device. Effect of the Invention

[0020] As explained above in detail, according to the present invention, it becomes possible to effectively remove airborne dust generated by blasting at a tunnel face. [Brief description of the drawings]

[0021] [Figure 1] 1A and 1B are cross-sectional views of the inside of a tunnel in a dust diffusion prevention mode and a dust removal mode, respectively, showing a method for removing suspended dust according to the present invention (first embodiment). [Diagram 2] 1A and 1B show a front view and a side view, respectively, of an electrically charged water particle spray device 2. FIG. [Diagram 3] 11A and 11B are cross-sectional views of the inside of a tunnel in a dust diffusion prevention mode and a dust removal mode, respectively, showing a method for removing suspended dust according to a second embodiment of the present invention. [Figure 4] FIG. 4 is a view taken along line IV-IV in FIG. [Diagram 5] 11A and 11B are cross-sectional views of the inside of a tunnel in a dust diffusion prevention mode and a dust removal mode, respectively, showing a method for removing suspended dust according to a third embodiment of the present invention. [Figure 6] 13A and 13B are cross-sectional views of the inside of a tunnel in a dust diffusion prevention mode and a dust removal mode, respectively, showing a method for removing suspended dust according to a fourth embodiment of the present invention. [Figure 7] FIG. 7 is a view taken along line VII-VII in FIG. [Figure 8]13A and 13B are cross-sectional views of the inside of a tunnel in a dust diffusion prevention mode and a dust removal mode, respectively, showing a method for removing suspended dust according to a fifth embodiment. [Figure 9] FIG. 13 is a cross-sectional view of the inside of a tunnel showing a method for removing suspended dust in accordance with a sixth embodiment. [Figure 10] FIG. 1 is a cross-sectional view of a tunnel showing a conventional method for removing suspended dust. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[0023] In the construction of mountain tunnels, heavy machinery for tunnel construction such as wheel jumbos, guns, and wheel loaders are placed near the tunnel face, and after the mini-bench method, in which the upper and lower halves are excavated in parallel at once, drilling holes for rock bolts and drilling holes and loading charges is performed in the upper and lower halves, respectively, by blasting the tunnel face, the upper and lower halves are cut down all at once, and then excavation is carried out in one cycle in the following order: removal of debris → hit detection → primary gunning → (construction of steel supports) → (secondary gunning) → installation of rock bolts. A center is also placed behind the tunnel face, where construction of the lining and invert construction are carried out.

[0024] The method for removing suspended dust after blasting of a tunnel face according to the present invention aims to spray charged water particles that are charged with an opposite charge to the dust suspended in the tunnel shaft after blasting of the tunnel face, thereby integrating the dust and the charged water by the electrostatic force acting between the charged water particles and the dust, accelerating the falling speed of the dust, and efficiently reducing the concentration of dust suspended in the tunnel shaft. The method for removing suspended dust according to the present invention will be described in detail below.

[0025] [First embodiment] In the method for removing suspended dust according to the first embodiment, as shown in FIG. 1(A), after blasting, the air blowing from the air duct 1 is stopped and a dust diffusion prevention mode is performed in which charged water particles are sprayed in the radial direction of the tunnel while moving in the direction of the tunnel face S, and then, as shown in FIG. 1(B), air blowing from the air duct 1 is started and a dust removal mode is performed in which charged water particles are sprayed in the forward direction while moving in the direction of the tunnel face S.

[0026] To explain the above-mentioned suspended dust removal method in more detail, the dust diffusion prevention mode starts immediately after blasting of the tunnel face and continues until the spraying of charged water particles in the radial direction of the tunnel is performed a certain distance in the direction of the face S, until it reaches a position a certain distance away from the face S, or until a certain amount of time has passed.

[0027] The blowing / stopping of air from the air duct 1 can be switched by turning on / off the blower fan connected to the air duct 1, and while the dust diffusion prevention mode is in operation, the blower fan is always stopped and the blowing of air from the air duct 1 is stopped.

[0028] The electrocharged water particles are sprayed while moving from a position sufficiently away from the tunnel face S toward the tunnel face S. The movement may be continuous at a constant speed, or the movement may be repeated such that the movement is decelerated or stopped at a predetermined position and sprayed for a certain period of time, the movement is moved a certain distance toward the tunnel face S, and the movement is decelerated or stopped again and sprayed for a certain period of time.

[0029] In order to spray the charged water particles while moving inside the tunnel, a vehicle 3 is used that is equipped with an electrically charged water particle spraying device 2 that can switch the spray direction of the electrically charged water particles to a predetermined direction. While the vehicle 3 is moving, the electrically charged water particles are sprayed by the mounted electrically charged water particle spraying device 2.

[0030] The electrically charged water particle spraying device 2 may be of any structure so long as it is configured so that the spray direction of the electrically charged water particles can be switched. As an example, as shown in FIG. 2, a device can be used which is configured of a fan 4 whose blowing direction is adjustable, and a plurality of spray nozzles 5 which are arranged at intervals circumferentially around the periphery of the blowing outlet of the fan 4 and which spray electrically charged water particles toward the center of the blown airflow.

[0031] The fan 4 is an axial fan in which blades driven by a motor are rotatably arranged in a cylindrical casing. The fan 4 is supported by supports 6, 6 provided on both sides of the casing so as to be rotatable around an axis perpendicular to the rotation axis of the blades, and a motor 7 is provided for rotating the fan 4 around the support 6. A substantially U-shaped frame 8 is provided to support the support 6, 6, and the frame 8 is supported by a support 9 provided in the center of the bottom so as to be rotatable around a substantially vertical axis, and a motor 10 is provided to rotate the frame 8 around the support 9. Furthermore, a stand for fixing the charged water particle spray device 2 to the vehicle 3 is provided below the support 9.

[0032] The vehicle 3 is a vehicle such as a truck capable of carrying heavy loads on the rear loading platform, and can move with or without a driver. When blasting the face S, the vehicle 3 waits at a position sufficiently far from the face S where it is not adversely affected by the blasting, and immediately after blasting, it sprays charged water particles into the tunnel using the charged water particle spraying device 2 mounted on it.

[0033] The vehicle 3 moves backward so that the platform on which the charged water particle spraying device 2 is mounted is at the front in the traveling direction.

[0034] Further, the vehicle 3 is equipped with a raw water tank 11 for supplying water to the charged water particle spray device 2 and a charging device 12.

[0035] In the dust diffusion prevention mode, the charged water particles are sprayed in the radial direction of the tunnel by the charged water particle spraying device 2. To spray the charged water particles in the radial direction of the tunnel, as shown in Fig. 1(A), the air outlet of the fan 4 is set facing upward, and the frame 8 is rotated so that the axial direction connecting the supports 6, 6 is parallel to the moving direction of the vehicle 3. In this state, the motor 7 is driven to swing the fan 4 around the supports 6, 6 within a predetermined angle range.

[0036] By spraying electrostatically charged water particles in the radial direction of the tunnel in dust diffusion prevention mode, dust that has diffused from the tunnel face to the portal and spread across the entire cross section of the tunnel can be effectively removed, and dust can be prevented from diffusing beyond the spraying position. At this time, the airflow from the air duct 1 is stopped, so dust is prevented from being carried by the wind from the air duct 1 and diffusing to the portal, and a high concentration of dust can be kept on the tunnel face S side.

[0037] After the dust diffusion prevention mode is completed, the dust removal mode is performed. In the dust removal mode, as shown in Fig. 1(B), the fan connected to the air duct 1 is operated to start blowing air from the air duct 1, and the vehicle 3 is moved further toward the face S from the position where the dust diffusion prevention mode was completed, while the charged water particle spraying device 2 sprays charged water particles forward.

[0038] In dust removal mode, air is blown from air duct 1 and electrostatically charged water particles are sprayed forward, pushing the dust diffusing toward the entrance back toward the face S, where it originates, narrowing the area of ​​high dust concentration and efficiently removing the dust by spraying electrostatically charged water particles there.

[0039] 1(B), to spray the charged water particles forward, the motor 10 in FIG. 2 is driven to rotate the frame 8 around the support 9 so that the axial direction connecting the supports 6, 6 on both sides of the casing faces the left-right direction perpendicular to the traveling direction of the vehicle 3, and the motor 7 is driven to rotate and move the fan 4 so that the air outlet faces forward. In this state, the motor 10 is driven to swing (pivot) the frame 8 around the support 9 within a predetermined angle range, thereby spraying the charged water particles forward in the traveling direction of the vehicle 3.

[0040] The direction in which the charged water particles are sprayed is forward along the direction of movement of the vehicle 3, and the angle range in the vertical direction relative to the direction of movement of the vehicle 3 is -90° to 90°, preferably -60° to 60°, and more preferably -45° to 45°.

[0041] The location at which the mode switches from the dust diffusion prevention mode to the dust removal mode is arbitrary, but it is preferable that the location is at least closer to the face S than the outlet of the air duct 1, and preferably is a location approximately 50 to 30 m away from the face S toward the mine entrance.

[0042] [Second embodiment example] The method for removing suspended dust according to the second embodiment is different from the first embodiment in the configuration of the charged water particle spray device as shown in Figs.

[0043] In the second embodiment, the charged water particle spraying device 2A has two pipes 20, 20 equipped with a plurality of spray nozzles capable of spraying charged water particles at intervals along the axial direction, which are erected at the rear of the bed of the vehicle 3 at a distance in the left-right direction, and the charged water particles are sprayed in a predetermined direction from the pipes 20. In the dust diffusion prevention mode, as shown in Fig. 4, spraying is performed in the left-right directions of the vehicle 3 and, if necessary, upward from the upper end of the pipes 20, and in the dust removal mode performed thereafter, spraying is performed forward in the direction of movement of the vehicle 3, as shown in Fig. 3(B).

[0044] The spray direction from the tube body 20 may be changed by rotating the tube body 20 around its axis to change the direction of the spray nozzle provided on the tube body 20, or the tube body 20 may be provided with multiple spray nozzles for the dust diffusion prevention mode and multiple spray nozzles for the dust removal mode, and charged water may be supplied to different systems of spray nozzles for each mode.

[0045] Furthermore, the tube 20 may be structured so as to be axially extendable or foldable so as not to get in the way when not in use.

[0046] In the method for removing suspended dust according to the second embodiment, the charged water particles can be sprayed radially all at once, making it possible to remove dust quickly.

[0047] [Third embodiment example] In the method for removing suspended dust according to the third embodiment, as shown in FIG. 5, an electrically charged water particle spraying device 2 consisting of a fan 4 and a spray nozzle 5 in the first embodiment is made capable of running along a rail 21 extending in the tunnel axial direction.

[0048] The rail 21 may be a separate one installed for the electrocharged water particle spraying device, but it is preferable to use a rail for underground lighting that extends along the axial direction of the tunnel at the top of the inner surface of the tunnel. This rail 21 is an I-beam fixed to the ceiling, and running wheels 22 are provided on the inner surface of both sides of the lower flange, spaced apart in the front-rear direction, and a running motor is connected to at least one of the running wheels 22, allowing the electrocharged water particle spraying device 2 to run along the rail 21.

[0049] The charged water particle spray device 2 is adapted to receive the charged water from a raw water tank 11 and a charging device 12 installed on the ground through a hose.

[0050] By allowing the device to run on the rails 21 provided on the ceiling surface, vehicles running on the ground are not required, and workability and safety can be improved. The rails may be installed not only on the ceiling surface, but also on the side of a tunnel or on the ground, as long as the charged water particle spray device 2 can run along the rails.

[0051] [Fourth embodiment] In the method for removing suspended dust according to the fourth embodiment, as shown in Figures 6 and 7, the charged water particles are sprayed while moving a charged water particle spraying device 2B which is capable of running along a rail 21 extending in the tunnel axial direction and capable of switching the spray direction of the charged water particles.

[0052] As shown in FIG. 7, the charged water particle spraying device 2B has a structure in which a plurality of spray nozzles are provided at intervals in the axial direction of a pipe body 23 that extends linearly in an approximately horizontal direction along the tunnel width direction.

[0053] In the dust diffusion prevention mode, charged water particles are sprayed downward from a spray nozzle provided on the lower peripheral surface of the tube body 23 extending in the substantially horizontal direction. In the dust removal mode performed thereafter, charged water particles are sprayed forward from a spray nozzle provided on the front peripheral surface of the tube body 23 extending in the substantially horizontal direction.

[0054] The spray direction of the charged water particles can be switched between the dust diffusion prevention mode and the dust removal mode by rotating the tube body 23 about its axis to change the direction of the spray nozzle provided on the tube body 23, or by providing the tube body 23 with a spray nozzle for the dust diffusion prevention mode and a spray nozzle for the dust removal mode, and supplying charged water to a different system of spray nozzles for each mode.

[0055] [Fifth embodiment] In the method for removing suspended dust according to the fifth embodiment, as shown in Fig. 8, the shape of the tubular body 24 is different from that of the fourth embodiment. In the fifth embodiment, the tubular body 24 is formed in an arch shape that conforms to the cross-sectional shape of the interior of the tunnel. In this fifth embodiment, the charged water particles are sprayed in an arch shape that conforms to the cross-sectional shape of the interior of the tunnel, so that dust can be removed more quickly.

[0056] [Sixth embodiment] The method for removing suspended dust according to the sixth embodiment is performed by mounting an electrically charged water particle spraying device on a drone such as (A) an aerial drone 25 or (B) a ground-traveling drone 26 (radio-controlled car), as shown in Fig. 9. By using such a remote-scanning drone, people do not need to approach the face, improving safety. [Explanation of symbols]

[0057] 1...air duct, 2...charged water particle spray device, 3...vehicle, 4...fan, 5...spray nozzle, 6...support, 7...motor, 8...frame, 9...support, 10...motor, 11...raw water tank, 12...charging device, 20...tube body, 21...rail, 22...running wheel, 23...tube body, 24...tube body, 25...flying drone, 26...ground-traveling drone, 50...air duct, 51...dust collector

Claims

1. A method for removing suspended dust after tunnel blasting by spraying electrostatically charged water particles into the tunnel, comprising: A method for removing suspended dust after blasting at a tunnel face, characterized by carrying out a dust diffusion prevention mode in which, after blasting, air flow from the air duct is stopped and the charged water particles are sprayed in the radial direction of the tunnel while moving toward the tunnel face, and then carrying out a dust removal mode in which air flow from the air duct is started and the charged water particles are sprayed in the forward direction while moving toward the tunnel face.

2. A method for removing suspended dust after blasting a tunnel face as described in claim 1, in which the charged water particles are sprayed while moving a vehicle or drone equipped with an charged water particle spraying device capable of switching the spray direction of the charged water particles.

3. 2. A method for removing suspended dust after blasting a tunnel face as described in claim 1, in which the charged water particles are sprayed while an charged water particle spraying device capable of switching the spray direction of the charged water particles is run along a rail extending in the direction of the tunnel axis.

4. A method for removing suspended dust after blasting a tunnel face as described in either claim 2 or 3, wherein the charged water particle spraying device comprises a fan with an adjustable blowing direction, and a spray nozzle arranged near the fan's outlet for spraying the charged water particles toward the blown airflow.

5. A method for removing suspended dust after blasting a tunnel face as described in either claim 2 or 3, wherein the charged water particle spraying device comprises a tube body and a plurality of spray nozzles for spraying the charged water particles, the spray nozzles being spaced apart in the axial direction of the tube body.

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