Device and method for reducing rebound and dust on a tunnel shotcrete work face

Abstract

The application discloses a device and method for reducing rebound rate of tunnel shotcrete and dust on working surface, which comprises a spraying trolley, a spraying collection mechanism is installed at the end of the mechanical arm of the spraying trolley, a quick-setting agent spraying mechanism, an air spraying mechanism and a dust collector are arranged on the spraying trolley; the method comprises the following steps: 1, starting the spraying trolley to spray concrete to the working surface of the tunnel; 2, primary filtration of the dust on the working surface and collection of rebounded materials; 3, secondary filtration and purification of the dust on the working surface; 4, re-spraying of the rebounded materials; 5, repeatedly performing steps 2-4 until the construction is completed. The collection cover with the elastic filter screen on the top can realize suction, collection and primary filtration of the dust-containing gas, and can also realize synchronous collection of the falling concrete rebounded materials, and the high-pressure air generated instantaneous strong airflow and the high elasticity recovery rate of the elastic filter screen are utilized to complete the re-spraying of the collected rebounded materials.

Description

Technical Field

[0001] This invention belongs to the technical field, specifically relating to an apparatus and method for reducing the rebound rate of shotcrete in tunnels and dust at the work site. Background Technology

[0002] In tunnel construction, shotcrete is a core material for initial support in tunnel engineering. The rebound rate of shotcrete refers to the ratio of rebound material not adhering to the sprayed surface to the total mass of shotcrete. It is a key indicator affecting construction quality and cost. Traditional shotcrete (C20, C25) generally has a rebound rate exceeding 25%. A high rebound rate leads to significant material waste, increasing construction costs and affecting efficiency due to increased material recycling frequency. Furthermore, an excessively high rebound rate can cause increased dust concentration at the work site, seriously endangering the physical and mental health of construction workers. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a device for reducing the rebound rate of shotcrete in tunnels and dust at the work site, in order to address the shortcomings of the prior art.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a device for reducing the rebound rate of shotcrete in tunnels and dust at the work site, including a shotcrete trolley, characterized in that: a shotcrete collection mechanism is installed at the end of the mechanical arm of the shotcrete trolley; the shotcrete trolley is equipped with a quick-setting agent spraying mechanism, an air spraying mechanism, and a dust collector; the shotcrete collection mechanism includes a collection hood and a material conveying pipe, an air outlet pipe, and a dust collection duct all connected to the bottom of the collection hood; the top of the collection hood is open and covered with a fixed elastic filter screen; a shotcrete head connected to the material conveying pipe and passing through the elastic filter screen is installed at the central axis of the collection hood; a shotcrete head air inlet pipe is also provided on one side of the shotcrete head; one end of the shotcrete head air inlet pipe is connected to the shotcrete head, and the other end of the shotcrete head air inlet pipe passes through the bottom of the truncated cone of the collection hood and is connected to the quick-setting agent spraying mechanism; the material conveying pipe is connected to the concrete pump pipe on the shotcrete trolley; the air outlet pipe is connected to the air spraying mechanism; and the dust collection duct is connected to the air inlet of the dust collector.

[0005] The aforementioned device for reducing the rebound rate of shotcrete in tunnels and dust at the work site is characterized in that: the spraying head passes through the bottom of the collection hood and is connected to the conveying pipe via a flange.

[0006] The aforementioned device for reducing the rebound rate of shotcrete in tunnels and dust at the work site is characterized in that: the accelerator spraying mechanism includes an accelerator storage tank for storing the accelerator, the accelerator storage tank is connected to the air inlet pipe of the spray head through a pump pipe, one end of the pump pipe near the accelerator storage tank is connected to a compressed air station through a first air inlet pipe, and a first valve is installed on the end of the first air inlet pipe near the pump pipe.

[0007] The aforementioned device for reducing the rebound rate of shotcrete in tunnels and dust at work sites is characterized in that: the air jetting mechanism includes a compressed air storage tank, which is connected to a compressed air station via a second air inlet pipe. A second valve is installed at the end of the second air inlet pipe near the compressed air storage tank. The outlet end of the compressed air storage tank is connected to an outlet pipe, which is equipped with an electromagnetic pulse valve at the end near the compressed air storage tank and an electric control valve at the end near the collection hood.

[0008] The aforementioned device for reducing the rebound rate of shotcrete in tunnels and dust at work sites is characterized in that: the dust collector includes a centrifugal fan, a dust collection filter cartridge, and an ash discharge valve located at the bottom of the dust collection filter cartridge; a current transformer is connected in series in the power supply circuit of the centrifugal fan.

[0009] The aforementioned device for reducing the rebound rate of shotcrete in tunnels and dust at work sites is characterized in that: the elastic filter screen comprises elastic fibers or elastic membrane cloth, and the pore size of the elastic fibers or elastic membrane cloth is 0.1mm to 2mm.

[0010] The aforementioned device for reducing the rebound rate of shotcrete in tunnels and dust at work sites is characterized in that: the dust collection filter cartridge is made of interwoven fibers with a fiber gap of 10μm to 50μm.

[0011] Meanwhile, the present invention also discloses a method for reducing the rebound rate of shotcrete in tunnels and dust at the work site, characterized by the following steps: Step 1: Start the spraying trolley to spray concrete onto the tunnel working face: Move the spraying trolley to the designated working face, adjust the angle and extension distance of the mechanical arm on the trolley, and start the concrete spraying operation. The concrete is transported to the delivery pipe through the pump pipe and mixed with the quick-setting agent and compressed air from the air inlet pipe of the spraying head. The spraying force generated by the compressed air carries the concrete to the working area to start the spraying operation. Step 2: Primary filtration of dust from the work surface and collection of rebound material: Turn on the dust collector located on the spray trolley, start the centrifugal fan, and the suction force generated by the centrifugal fan is transmitted to the collection hood through the dust collection duct. A large-scale suction force is generated in the top area of ​​the collection hood. The dust from the work surface is sucked to the elastic filter screen at the top of the collection hood. When the dust particle size of the work surface is larger than the first dust particle size threshold, it is adsorbed by the elastic filter screen. When the dust particle size at the work surface is not greater than the first dust particle size threshold, the dust at the work surface passes through the elastic filter and completes one filtration before entering the collection hood. The collection hood is tightly fixed to the spray head and moves in real time with the spray head during operation. It can collect dust generated near the spray head at the source and effectively inhibit the dust from continuing to spread to the work surface. During the spraying operation, the concrete rebound material generated near the spray head will fall onto the surface of the elastic filter screen on top of the collection hood; Step 3: Secondary filtration and purification of dust at the work surface: The dust-laden gas entering the collection hood is drawn through the dust collection duct to the dust collector on the jetting trolley. Secondary filtration and purification are completed in the dust collection filter cartridges inside the dust collector, effectively intercepting and filtering out fine dust particles in the dust-laden gas. After dust collection, the dust concentration in the outlet gas is <10mg / m³. 3 Finally, the clean gas is discharged into the atmosphere by a centrifugal fan, while the collected dust remains inside the dust collector and is discharged through the ash discharge valve at the bottom of the dust collector. Step 4, Re-spraying of rebound material: At the same time as the spraying and dust collection operation begins, open the second valve to allow external compressed air to enter the compressed air storage tank and complete the storage of compressed gas in the tank. As the spraying operation progresses, the amount of rebound material collected by the elastic filter screen at the top of the collection hood gradually increases and accumulates on the elastic filter screen. At this time, the filter screen pores are gradually blocked by the rebound material, and the operating resistance of the dust collector increases. When the current value collected by the current transformer is greater than the preset current threshold, the electromagnetic pulse valve precisely controls and opens the electric control valve. The high-pressure gas accumulated inside the compressed air tank is instantly and quickly discharged, generating an instantaneous airflow. The airflow impact force quickly rushes into the collection hood through the air outlet pipe and acts directly on the elastic filter screen. The rebound material attached to the surface of the elastic filter screen is impacted and, with the help of the elastic filter screen's rebound force, detaches from the surface of the elastic filter screen and directly rebounds to the spraying operation surface, completing the re-spraying of the rebound material. The fallen rebound material is reused and sprayed to adhere to the operation surface, reducing the total amount of rebound material during the spraying process, thereby effectively reducing the rebound rate during the overall shotcrete operation. After being impacted and vibrated, the elastic filter screen loses the rebound material accumulated on its surface and the material clogging the filter screen pores. After cleaning, the dust collection resistance of the filter screen decreases and the dust collection effect is restored. Step 5: Repeat steps 2 through 4 multiple times until construction is completed.

[0012] The above-mentioned method for reducing the rebound rate of shotcrete in tunnels and dust at the work site is characterized in that: the particle size of the rebound material is 2mm to 10mm, and the particle size of the rebound material is larger than the pore size of the elastic fiber or elastic membrane. Compared with the prior art, the present invention has the following advantages: 1. The device used in this invention requires less additional equipment compared to existing equipment and processes, which can significantly reduce the rebound rate of shotcrete, reduce construction costs, and at the same time reduce dust concentration at the work site, improve the working environment at the work site. The solution is economical, feasible, flexible and convenient, and suitable for shotcrete construction in long-distance tunnels.

[0013] 2. The device used in this invention employs a collection hood with an elastic filter screen on top, which can not only achieve the suction, collection, and primary filtration of dust-laden gas, but also simultaneously collect fallen concrete rebound material. The powerful instantaneous airflow generated by high-pressure air and the high elasticity recovery rate of the elastic filter screen are used to complete the re-spraying of the collected rebound material.

[0014] 3. The method adopted in this invention is simple in steps. After the elastic filter screen is impacted and vibrated, the rebound material accumulated on the surface and the material blocking the filter screen pores are also cleaned up and removed from the surface of the filter bag in time, realizing the dust removal effect of the filter screen. After the filter screen is cleaned, the dust collection resistance is reduced and the dust collection effect is restored. This process is completed instantly and will not have a significant impact on the spraying and dust collection operations.

[0015] 4. The collection hood of this invention is fixed to the outside of the nozzle and moves closely with the nozzle during operation, collecting dust generated near the nozzle at its source and effectively preventing dust from spreading to the surrounding work surface. Furthermore, after secondary filtration and purification, the dust concentration in the gas is <10mg / m³. 3 This greatly improved the working environment.

[0016] In summary, the present invention is novel and reasonable. It adopts a collection cover with an elastic filter screen on the top, which can not only realize the suction, collection and primary filtration of dust-laden gas, but also simultaneously collect the fallen concrete rebound material. The instantaneous strong airflow generated by high-pressure air and the high elastic recovery rate of the elastic filter screen are used to complete the re-spraying of the collected rebound material.

[0017] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structural connection of the device used in this invention.

[0019] Figure 2 This is a schematic diagram of the spray collection mechanism of the present invention.

[0020] Figure 3 This is a schematic diagram of the air injection mechanism of the present invention.

[0021] Figure 4 This is a schematic diagram of the dust collector of the present invention.

[0022] Figure 5 This is a flowchart of the method of the present invention.

[0023] Explanation of reference numerals in the attached figures: 1—Spraying trolley; 2—Robotic arm; 3—Collection hood; 4—Air injection mechanism; 5—Dust collector; 6—Accelerator storage tank; 7—Pump pipe; 8—First air inlet pipe; 9—First valve; 10—Feeding pipe; 11—Elastic filter screen; 12—Spray head; 13—Flange; 14—Outlet pipe; 15—Dust collection duct; 16—Inlet pipe for the injector head; 17—Electric control valve; 18—Compressed air storage tank; 19—Second intake pipe; 20—Second valve; 21—Solenoid pulse valve; 22—Air inlet; 23—Dust collection filter cartridge; 24—Centrifugal fan; 25—Ash discharge valve. Detailed Implementation

[0024] like Figures 1 to 4 As shown, the device for reducing the rebound rate of shotcrete in tunnels and dust at the work site according to the present invention includes a shotcrete trolley 1. A shotcrete collection mechanism is installed at the end of the mechanical arm 2 of the shotcrete trolley 1. The shotcrete trolley 1 is equipped with a quick-setting agent spraying mechanism, an air spraying mechanism 4, and a dust collector 5. The shotcrete collection mechanism includes a collection hood 3 and a material conveying pipe 10, an air outlet pipe 14, and a dust collection duct 15, all connected to the bottom of the collection hood 3. The top of the collection hood 3 is open and covered with a fixed elastic filter screen 11. A spray head 12 is installed at the central axis of the collection hood 3, which is connected to the conveying pipe 10 and passes through the elastic filter screen 11. A spray head air inlet pipe 16 is also provided on one side of the spray head 12. One end of the spray head air inlet pipe 16 is connected to the spray head 5, and the other end of the spray head air inlet pipe 16 passes through the bottom of the truncated cone of the collection hood 3 and is connected to the quick-setting agent spraying mechanism. The conveying pipe 10 is connected to the concrete pump pipe on the spraying trolley 1, the air outlet pipe 14 is connected to the air spraying mechanism 4, and the dust collection air pipe 15 is connected to the air inlet 22 of the dust collector 5.

[0025] It should be noted that the device used requires less additional equipment compared to existing equipment and processes, which can significantly reduce the rebound rate of shotcrete, reduce construction costs, and at the same time reduce dust concentration at the work site, improving the working environment. The solution is economical, feasible, flexible and convenient, and suitable for shotcrete construction in long-distance tunnels. The device uses a collection hood with an elastic filter screen on top, which can not only suck up, collect and filter dust-laden gas, but also collect fallen concrete rebound material at the same time. The instantaneous strong airflow generated by high-pressure air and the high elasticity recovery rate of the elastic filter screen are used to complete the re-spraying of the collected rebound material.

[0026] In actual use, the collection hood is truncated cone-shaped, with an open top covered and fixed with an elastic filter screen. The bottom of the cone and the outer circumference are completely sealed. The bottom of the collection hood is firmly connected to the spray head and tightly surrounds and is fixed to the spray head. During operation, it will move closely with the spray head.

[0027] In this embodiment, the spray head 12 passes through the bottom of the collection hood 3 and is connected to the conveying pipe 10 via the flange 13.

[0028] In this embodiment, the accelerator spraying mechanism includes an accelerator storage tank 6 for storing accelerator. The accelerator storage tank 6 is connected to the air inlet pipe 16 of the spray head through a pump pipe 7. The end of the pump pipe 7 near the accelerator storage tank 6 is connected to a compressed air station through a first air inlet pipe 8. A first valve 9 is installed at the end of the first air inlet pipe 8 near the pump pipe 7.

[0029] In this embodiment, the air injection mechanism 4 includes a compressed air tank 18, which is connected to a compressed air station via a second air inlet pipe 19. A second valve 20 is installed at one end of the second air inlet pipe 19 near the compressed air tank 18. The air outlet of the compressed air tank 18 is connected to an air outlet pipe 14, which is equipped with an electromagnetic pulse valve 21 at one end of the air outlet pipe 14 near the compressed air tank 18, and an electric control valve 17 at one end of the air outlet pipe 14 near the collection hood 3.

[0030] In this embodiment, the dust collector 5 includes a centrifugal fan 24, a dust collection filter cartridge 23, and an ash discharge valve 25 disposed at the bottom of the dust collection filter cartridge 23. A current transformer is connected in series in the power supply circuit of the centrifugal fan 24.

[0031] In this embodiment, the elastic filter 11 includes elastic fibers or elastic membrane fabric, and the pore size of the elastic fibers or elastic membrane fabric is 0.1mm to 2mm.

[0032] In this embodiment, the dust collection filter cartridge 23 is made of interwoven fibers with a fiber gap of 10μm to 50μm.

[0033] like Figure 5 The method shown includes the following steps to reduce the rebound rate of shotcrete in tunnels and dust at the work site: Step 1: Start the spraying trolley to spray concrete onto the tunnel working face: Move the spraying trolley 1 to the designated working face, adjust the rotation angle and extension distance of the mechanical arm 2 on the trolley, and start the concrete spraying operation. The concrete is transported to the delivery pipe 10 through the pump pipe, and mixed with the quick-setting agent and compressed air from the air inlet pipe 16 of the spraying head 12. The spraying force generated by the compressed air carries the concrete to the working area to start the spraying operation. Step 2: Primary filtration of dust from the work surface and collection of rebound material: Turn on the dust collector 5 located on the spray trolley, start the centrifugal fan 24, and the suction force generated by the centrifugal fan is transmitted to the collection hood 3 through the dust collection duct 15. A large-scale suction force is generated in the top area of ​​the collection hood 3. The dust from the work surface is sucked onto the elastic filter screen 11 at the top of the collection hood 3. When the dust particle size of the work surface is larger than the first dust particle size threshold, it is adsorbed by the elastic filter screen 11. When the dust particle size of the working surface is not greater than the first dust particle size threshold, the dust of the working surface passes through the elastic filter 11 and completes one filtration before entering the collection hood 3. The collection hood 3 is tightly fixed on the spray head 12 and will move in real time with the spray head during operation. It can collect dust generated near the spray head at the source and effectively inhibit the dust from continuing to spread to the working surface. During the spraying operation, the concrete rebound material generated near the spray head will fall onto the surface of the elastic filter screen 11 on top of the collection hood 3; Step 3: Secondary filtration and purification of dust at the work site: The dust-laden gas entering the collection hood 3 is drawn through the dust collection duct 15 into the dust collector 5 on the jetting trolley. Secondary filtration and purification are completed in the dust collection filter cartridge 23 inside the dust collector, effectively intercepting and filtering out fine dust particles in the dust-laden gas. After dust collection, the dust concentration in the outlet gas is <10mg / m³. 3 Finally, the clean gas is discharged into the atmosphere by the centrifugal fan 24, while the collected dust remains inside the dust collector and is discharged through the ash discharge valve 25 at the bottom of the dust collector. Step 4, Re-spraying of rebound material: At the same time as the spraying and dust collection operation begins, open the second valve 20 to allow external compressed air to enter the compressed air storage tank 18 and complete the storage of compressed gas in the tank. As the spraying operation progresses, the amount of rebound material collected by the elastic filter at the top of the collection hood 3 gradually increases and accumulates on the elastic filter 11. At this time, the filter pores are gradually blocked by the rebound material, and the operating resistance of the dust collector 5 increases. When the current value collected by the current transformer is greater than the preset current threshold, the electromagnetic pulse valve 21 precisely controls and opens the electric control valve 17. The high-pressure gas accumulated inside the compressed air tank 18 is instantly and quickly discharged, generating an instantaneous airflow. The airflow impact force rushes into the collection hood 3 through the air outlet pipe 14 and acts directly on the elastic filter 11. The rebound material attached to the surface of the elastic filter is impacted and, with the help of the elastic filter's rebound force, detaches from the surface of the elastic filter and directly rebounds to the spraying operation surface, completing the re-spraying of the rebound material. The fallen rebound material is reused and sprayed to adhere to the operation surface, reducing the total amount of rebound material during the spraying process, thereby effectively reducing the rebound rate during the overall shotcrete operation. After being impacted and vibrated, the elastic filter 11 loses the rebound material accumulated on its surface and the material clogging the filter pores. After cleaning, the dust collection resistance of the filter is reduced and the dust collection effect is restored. Step 5: Repeat steps 2 through 4 multiple times until construction is completed.

[0034] In this embodiment, the particle size of the rebound material is 2mm to 10mm, which is larger than the pore size of the elastic fiber or elastic membrane.

[0035] It should be noted that the elastic filter is composed of elastic fibers or elastic membrane cloth with a certain elastic recovery rate. The material has the characteristics of high elongation and high elastic recovery rate, and can undergo a certain deformation without breaking. The rebound material attached to the surface of the elastic filter is subjected to a strong impact force and, with the help of the rebound force of the elastic filter, detaches from the surface of the elastic filter and bounces directly to the spraying operation surface to complete the re-spraying of the rebound material. In use, the collection hood moves closely following the spray nozzle during operation, targeting and collecting dust at its source near the nozzle. This effectively prevents dust from spreading further to the work surface, improving the working environment. Furthermore, the dust-laden gas undergoes secondary filtration and purification, resulting in an outlet gas dust concentration of less than 10 mg / m³. 3 The dust-laden gas is fully purified. High-pressure air is used to blow air onto the elastic filter screen, which not only allows the rebound material that falls onto the elastic screen to be sprayed a second time, but also intermittently cleans the surface and pores of the elastic filter screen, ensuring the normal operation of the dust collector. The opening threshold of the high-pressure air solenoid valve can be adjusted according to the accumulation rate of the rebound material falling onto the elastic filter screen, thereby adjusting the high-pressure air blowing interval and realizing automatic cleaning of the elastic filter screen.

[0036] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Any simple modifications, alterations, or equivalent structural changes made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A device for reducing the rebound rate of shotcrete in tunnels and dust at the work site, comprising a shotcrete trolley (1), characterized in that: The spraying trolley (1) has a spraying collection mechanism installed at the end of its robotic arm (2). The spraying trolley (1) is equipped with a quick-setting agent spraying mechanism, an air spraying mechanism (4), and a dust collector (5). The spraying collection mechanism includes a collection hood (3) and a conveying pipe (10), an air outlet pipe (14), and a dust collection air pipe (15) all connected to the bottom of the collection hood (3). The top of the collection hood (3) is open and covered with a fixed elastic filter screen (11). A pipe connected to the conveying pipe (10) and extending through the central axis of the collection hood (3) is installed. The elastic filter (11) has a spray head (12), and a spray head air inlet pipe (16) is provided on one side of the spray head (12). One end of the spray head air inlet pipe (16) is connected to the spray head (12), and the other end of the spray head air inlet pipe (16) passes through the bottom of the truncated cone of the collection hood (3) and is connected to the quick-setting agent spraying mechanism; the conveying pipe (10) is connected to the concrete pump pipe on the spraying trolley (1), the air outlet pipe (14) is connected to the air spraying mechanism (4), and the dust collection pipe (15) is connected to the air inlet (22) of the dust collector (5); The air injection mechanism (4) includes a compressed air tank (18), which is connected to a compressed air station via a second air inlet pipe (19). A second valve (20) is installed at one end of the second air inlet pipe (19) near the compressed air tank (18). The outlet end of the compressed air tank (18) is connected to an outlet pipe (14). An electromagnetic pulse valve (21) is installed at one end of the outlet pipe (14) near the compressed air tank (18), and an electric control valve (17) is installed at one end of the outlet pipe (14) near the collection hood (3). The dust collector (5) includes a centrifugal fan (24), a dust collection filter cartridge (23) and an ash discharge valve (25) located at the bottom of the dust collection filter cartridge (23). A current transformer is connected in series in the power supply circuit of the centrifugal fan (24). When the current value collected by the current transformer is greater than the preset current threshold, the electromagnetic pulse valve (21) precisely controls and opens the electric control valve (17), and the high-pressure gas accumulated inside the compressed air tank (18) is discharged instantly and quickly, generating an instantaneous airflow. The airflow impact force rushes into the collection hood (3) through the air outlet pipe (14) and acts directly on the elastic filter screen (11).

2. The device for reducing the rebound rate of shotcrete in tunnels and dust at the work site as described in claim 1, characterized in that: The spray head (12) passes through the bottom of the collection hood (3) and is connected to the conveying pipe (10) via a flange (13).

3. The device for reducing the rebound rate of shotcrete in tunnels and dust at the work site as described in claim 1, characterized in that: The accelerator injection mechanism includes an accelerator storage tank (6) for storing accelerators. The accelerator storage tank (6) is connected to the air inlet pipe (16) of the injection head through a pump pipe (7). The end of the pump pipe (7) near the accelerator storage tank (6) is connected to a compressed air station through a first air inlet pipe (8). A first valve (9) is installed at the end of the first air inlet pipe (8) near the pump pipe (7).

4. The device for reducing the rebound rate of shotcrete in tunnels and dust at the work site as described in claim 1, characterized in that: The elastic filter (11) includes elastic fibers or elastic membrane fabric, and the pore size of the elastic fibers or elastic membrane fabric is 0.1 mm to 2 mm.

5. The device for reducing the rebound rate of shotcrete in tunnels and dust at the work site as described in claim 1, characterized in that: The dust collection filter cartridge (23) is made of interwoven fibers with a fiber gap of 10μm to 50μm.

6. A method for reducing the rebound rate of shotcrete in tunnels and reducing dust at the work site using the device as described in claim 4, characterized in that: The method includes the following steps: Step 1: Start the spraying trolley to spray concrete onto the tunnel working face: Move the spraying trolley (1) to the designated working face, adjust the rotation angle and extension distance of the mechanical arm (2) on the trolley, and start the concrete spraying operation. The concrete is transported to the delivery pipe (10) through the pump pipe and mixed with the quick-setting agent and compressed air from the air inlet pipe (16) of the spraying head (12). The spraying force generated by the compressed air carries the concrete to the working area to start the spraying operation. Step 2: Primary filtration of dust from the work surface and collection of rebound material: Turn on the dust collector (5) located on the spray trolley, start the centrifugal fan (24), and the suction force generated by the centrifugal fan is transmitted to the collection hood (3) through the dust collection duct (15). A large-scale suction force is generated in the top area of ​​the collection hood (3). The dust from the work surface is sucked to the elastic filter screen (11) at the top of the collection hood (3). When the dust particle size of the work surface is greater than the first dust particle size threshold, it is adsorbed by the elastic filter screen (11). When the dust particle size of the working surface is not greater than the first dust particle size threshold, the dust of the working surface passes through the elastic filter (11) and completes one filtration before entering the inside of the collection hood (3); the collection hood (3) is tightly fixed on the spray head (12) and will move in real time with the spray head during operation, so as to collect the dust generated near the spray head at the source and effectively suppress the dust from continuing to spread to the working surface. During the spraying operation, the concrete rebound material generated near the spray head will fall onto the surface of the elastic filter screen (11) on top of the collection hood (3); Step 3: Secondary filtration and purification of dust at the work site: The dust-laden gas entering the collection hood (3) is drawn into the dust collector (5) on the jetting trolley through the dust collection duct (15). Secondary filtration and purification are completed in the dust collection filter cartridge (23) inside the dust collector, which fully intercepts and filters the fine dust in the dust-laden gas. After dust collection, the dust concentration of the outlet gas is <10mg / m³. 3 Finally, the clean gas is discharged into the atmosphere by the centrifugal fan (24), and the collected dust remains inside the dust collector and is discharged through the ash discharge valve (25) at the bottom of the dust collector. Step 4, Re-spraying of rebound material: At the same time as the spraying and dust collection operation begins, open the second valve (20) to allow external compressed air to enter the compressed air storage tank (18) and complete the storage of compressed gas in the storage tank; As the spraying operation proceeds, the amount of rebound material collected by the elastic filter at the top of the collection hood (3) gradually increases and accumulates on the elastic filter (11). At this time, the filter pores are gradually covered and blocked by the rebound material, and the operating resistance of the dust collector (5) increases. When the current value collected by the current transformer is greater than the preset current threshold, the electromagnetic pulse valve (21) precisely controls and opens the electric control valve (17). The high-pressure gas accumulated inside the compressed air tank (18) is discharged instantly and quickly, generating an instantaneous airflow. The airflow impact force rushes into the collection hood (3) through the air outlet pipe (14) and acts directly on the elastic filter (11). The rebound material attached to the surface of the elastic filter is impacted and, with the help of the rebound force of the elastic filter, it is removed from the surface of the elastic filter and directly rebounds to the spraying operation surface, completing the re-spraying of the rebound material. The fallen rebound material is reused and sprayed to adhere to the operation surface, reducing the total amount of rebound material during the spraying process, thereby effectively reducing the rebound rate during the overall shotcrete operation. After the elastic filter screen (11) is impacted and vibrated, the rebound material accumulated on the surface and the material blocking the filter screen pores are removed from the filter screen surface. After the filter screen is cleaned, the dust collection resistance is reduced and the dust collection effect is restored. Step 5: Repeat steps 2 through 4 multiple times until construction is completed.

7. The method for reducing the rebound rate of shotcrete in tunnels and reducing dust at the work site according to claim 6, characterized in that: The particle size of the rebound material is 2mm to 10mm, and the particle size of the rebound material is larger than the pore size of the elastic fiber or elastic membrane.

Images