A device to prevent rebound of initial shotcrete in tunnels

Abstract

This utility model provides a device for preventing rebound of shotcrete in tunnels, including a main frame, a strong magnetic base, a barrier net, a jacking mechanism, a scraper plate, and hydraulic struts. After the steel arch frame is erected in the tunnel and before concrete spraying, the main frame is attached to the steel arch frame, and the anti-rebound device is attached to the surface of the steel arch frame using the strong magnetic base. Concrete is sprayed by placing the nozzle inside the barrier net, which effectively intercepts rebound particles and prevents the fresh layer from falling off. After spraying, the jacking mechanism pushes the scraper plate to move repeatedly, smoothing the sprayed concrete. This greatly reduces the amount of rebound of the shotcrete, saves concrete usage, reduces construction costs, and improves the construction quality of shotcrete.

Description

Technical Field

[0001] This utility model belongs to the field of tunnel construction machinery technology, and more specifically, it relates to a device for preventing rebound of initial shotcrete in tunnels. Background Technology

[0002] The construction principle of shotcrete involves loading a pre-mixed material into a shotcrete machine, using high-pressure air to deliver it to the nozzle, where it mixes with a quick-setting agent and is sprayed at high speed onto the surface of rock or concrete. Shotcrete application to the initial support of tunnels involves a large volume of work and is a crucial part of tunnel construction. However, the most commonly used wet shotcrete technique still suffers from significant rebound in practice. Currently, the overconsumption of shotcrete in the initial support of all tunnels remains a serious problem. Investigations of shotcrete application in multiple tunnels have revealed that during wet shotcrete application, concrete rebound occurs, with rebound rates generally around 20% to 30%, resulting in substantial waste of shotcrete, high construction costs, and severely impacting construction quality. Therefore, reducing the rebound rate of shotcrete is a pressing issue in this field. To improve shotcrete quality while reducing construction costs and increasing economic efficiency, the inventor team has repeatedly improved the process based on actual field conditions and developed a shotcrete anti-rebound device for tunnel initial support. Utility Model Content

[0003] The purpose of this utility model is to provide a device for preventing rebound of shotcrete in tunnels. It uses a barrier net to intercept rebound particles and a scraper plate to smooth the shotcrete, thereby reducing construction costs and improving construction quality.

[0004] To achieve the above objectives, this utility model provides a tunnel initial shotcrete anti-rebound device, comprising a main frame, strong magnetic feet, a barrier net, a jacking mechanism, a scraper plate, and hydraulic struts. The main frame includes two columns spaced apart and an upper beam, a middle beam, and a lower beam connected between the two columns, arranged alternately from top to bottom. Four strong magnetic feet are positioned at the four opposite corners of the main frame. The barrier net includes an upper baffle and a lower baffle, with the upper baffle rotatably connected to the top of the upper beam. The lower baffle is located below the upper baffle and has two sliding passages. Each sliding channel has a column running through it, and the length of the sliding channel extends along both ends of the lower retaining mesh on both sides of the main frame. The scraper plate is rotatably connected to one end of the lower retaining mesh, and the end of the lower retaining mesh connected to the scraper plate is located on the same side of the main frame as the strong magnetic foot. The jacking mechanism is located on the middle beam, and the telescopic end of the jacking mechanism is connected to a moving beam. The moving beam is slidably connected between the two columns and is located between the upper beam and the middle beam. The moving beam is connected to the side of the scraper plate facing away from the sprayed rock face of the tunnel. The two ends of the hydraulic strut are hinged to the lower retaining mesh and the moving beam, respectively, and the hydraulic strut is located on the side of the lower retaining mesh facing away from the sprayed rock face.

[0005] Preferably, the anti-rebound device for the initial shotcrete in the tunnel also includes a locking mechanism installed on the column, which is used to clamp the steel arch frame.

[0006] Preferably, the locking mechanism includes a pneumatic chuck or a manual chuck.

[0007] Preferably, the main frame is a rectangular frame structure.

[0008] Preferably, guide grooves are provided on opposite sides of the two columns, and both ends of the movable beam are inserted into the guide grooves.

[0009] Preferably, the jacking mechanism is a jacking cylinder, the top of the cylinder body of the jacking cylinder is fixed on the middle beam, the middle beam is provided with a through hole, and the telescopic end of the jacking cylinder is connected to the moving beam through the through hole.

[0010] Preferably, the side of the middle beam facing the upper beam is provided with an embedding groove for inserting the movable beam.

[0011] Compared with the prior art, the beneficial effects of the anti-rebound device for initial shotcrete in tunnels provided by this utility model are as follows:

[0012] (1) After the steel arch frame is erected in the tunnel and before concrete spraying, the main frame is attached to the steel arch frame, and the anti-rebound device is attached to the surface of the steel arch frame by using strong magnetic foot base. The nozzle is placed inside the barrier net for concrete spraying, thereby effectively intercepting rebound particles and preventing fresh layer from falling. After spraying, the jacking mechanism pushes the scraper plate to move repeatedly to scrape the sprayed concrete, effectively preventing concrete rebound. The amount of rebound of sprayed concrete can be reduced to less than 5%, which greatly reduces the excess consumption of concrete, saves the amount of concrete used, reduces construction costs, and improves the construction quality of sprayed concrete.

[0013] (2) This device is easy to operate, safe and reliable, and effectively promotes quality control at the tunnel construction site and improves the level of refined management of the project. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 A front view of a tunnel shotcrete anti-rebound device provided for an embodiment of this utility model;

[0016] Figure 2A rear view of a tunnel shotcrete anti-rebound device provided for an embodiment of this utility model;

[0017] Figure 3 A schematic diagram of the working state of a tunnel shotcrete anti-rebound device provided for an embodiment of this utility model.

[0018] The details of the reference numerals used in the above figures are as follows:

[0019] 10. Main frame; 101. Column; 102. Upper beam; 103. Middle beam; 104. Lower beam; 20. Strong magnetic foot; 30. Barrier net; 301. Upper barrier net; 302. Lower barrier net; 303. Sliding channel; 40. Pushing mechanism; 401. Telescopic end; 50. Scraper plate; 60. Hydraulic strut; 70. Moving beam; 80. Locking mechanism. Detailed Implementation

[0020] To make the technical problems, technical solutions, and beneficial effects of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model. Example 1

[0021] See Figures 1 to 3As shown, this utility model provides a tunnel initial shotcrete anti-rebound device, including a main frame 10, strong magnetic feet 20, a barrier net 30, a jacking mechanism 40, a scraper plate 50, and a hydraulic support rod 60. The main frame 10 includes two columns 101 spaced apart and an upper beam 102, a middle beam 103, and a lower beam 104 connected between the two columns 101. The upper beam 102, middle beam 103, and lower beam 104 are arranged alternately from top to bottom. There are four strong magnetic feet 20, which are respectively located at the four opposite corners of the main frame 10. The barrier net 30 includes an upper baffle 301 and a lower baffle 302. The upper baffle 301 is rotatably connected to the top of the upper beam 102. The lower baffle 302 is located below the upper baffle 301 and has two sliding channels 303. Each sliding channel 303 has a column 101 passing through it. The length of the sliding channel 303 extends along both ends of the lower baffle 302 on both sides of the main frame 10. The scraper plate 50 is rotatably connected to one end of the lower baffle 302, and the end of the lower baffle 302 connected to the scraper plate 50 is located on the same side of the main frame 10 as the strong magnetic foot seat 20. The jacking mechanism 40 is located on the middle beam 103. The telescopic end 401 of the jacking mechanism 40 is connected to the moving beam 70. The moving beam 70 is slidably connected between the two columns 101, and is located between the upper beam 102 and the middle beam 103. The moving beam 70 is connected to the side of the scraper plate 50 facing away from the sprayed rock surface of the tunnel. The two ends of the hydraulic strut 60 are hinged to the lower baffle 302 and the moving beam 70, respectively. The hydraulic strut 60 is located on the side of the lower baffle 302 facing away from the sprayed rock surface. The initial support structure mainly consists of shotcrete and steel arch frames. In this embodiment, the main frame 10 is a rectangular frame structure with two columns 101 parallel to each other, and the upper beam 102, middle beam 103 and lower beam 104 parallel to each other. For example, the main frame 10 is welded from I-beams, and its dimensions are 1.3m high and 0m wide.The width of the main frame 10 is 6m, equal to the installation distance of the steel arch frame on site, to accommodate the installation width. The strong magnetic feet 20 are made of neodymium iron boron magnets with a magnetic force of up to 20KG. They are installed at the four opposite corners of the main frame 10 to attach the anti-rebound device to the surface of the steel arch frame. The barrier net 30 is made of 2mm thick steel plate with a mesh radius of 5mm and a center-to-center distance of 20mm between adjacent meshes. The upper barrier net 301 is 1200mm long and 300mm wide, and the lower barrier net 302 is 1200mm long and 500mm wide. The upper and lower barrier nets 301 and 302 are used to block the rebound of sprayed concrete. One end of the upper barrier net 301 is connected to the upper beam 102 via a pivot. During construction, the upper barrier net 301 is positioned... On the side of the main frame 10 away from the sprayed rock surface, the nozzle extends into the main frame 10 and moves up, down, left, and right to spray. The upper baffle 301 can rotate up and down with the nozzle, intercepting rebound particles without affecting the nozzle movement. The pushing mechanism 40 is a pushing cylinder. The top of the cylinder body is fixed to the middle beam 103. The middle beam 103 has a through hole. The telescopic end of the pushing cylinder passes through the through hole and connects to the moving beam 70. The telescopic end of the pushing cylinder moves, thereby driving the moving beam 70 to move between the upper beam 102 and the middle beam 103. Guide grooves are respectively provided on the opposite sides of the two columns 101. The two ends of the moving beam 70 are inserted into the guide grooves. The guide grooves extend along the height direction of the columns 101. The two ends of the moving beam 70 can... The guide chute slides along its inner wall, providing guidance for the moving beam 70. The middle beam 103 has an embedding groove on the side facing the upper beam 102, extending along the length of the middle beam 103. The groove is wide enough to accommodate the moving beam 70, and its width is slightly larger than the width of the moving beam 70. When the jacking cylinder extends or retracts, it moves the moving beam 70 into and out of the embedding groove. The scraper plate 50 is used to smooth the sprayed concrete. For example, the scraper plate 50 is made of a 5mm thick steel plate, 1200mm long and 50mm wide, and is mounted on the lower baffle 302 via a pivot. The extension or retraction of the jacking cylinder causes the moving beam 70 to rotate the scraper plate 50 around the pivot of the scraper plate 50 and the lower baffle 302, thus allowing the scraper plate 50 to rotate on the sprayed rock surface of the tunnel. At any working position, it can match the curvature of the sprayed rock surface to smooth the sprayed concrete. The hydraulic strut 60 has a telescopic positioning function. For example, a Deheng QD type gas spring lockable and controllable hydraulic rod is selected, with a center distance range of 560-600mm, a pressure range of 30-200N, and a stroke of 260mm. The extension and retraction of the hydraulic strut 60 drives the lower baffle 302 to move along the height direction of the column 101 to adjust the tilt angle of the lower baffle 302, so as to cooperate with the upper baffle 301 to open or close the barrier net 30, allowing the nozzle to extend into or out of the barrier net 30. In this embodiment, the sliding channel 303 is rectangular, and its length extends along the width direction of the lower baffle 302. The width of the sliding channel 303 is slightly larger than the width of the column 101. Example 2

[0022] See Figures 1 to 3 As shown, the following describes a tunnel shotcrete anti-rebound device according to Embodiment 2 of this utility model. The difference between this embodiment and Embodiment 1 is that the tunnel shotcrete anti-rebound device further includes a locking mechanism 80 mounted on the column 101. The locking mechanism 80 is used to clamp the steel arch frame. Preferably, the locking mechanism includes pneumatic or manual clamps. Pneumatic clamps are existing common components; the clamps are opened or closed by a cylinder to clamp or release the steel arch frame, thereby further fixing the anti-rebound device to the steel arch frame. In this embodiment, there are two pneumatic clamps, symmetrically mounted on the two columns 101.

[0023] The working principle of the anti-rebound device for initial shotcrete in tunnels provided by this utility model is as follows:

[0024] The anti-rebound device for initial shotcrete in tunnels mainly consists of a main frame 10, a strong magnetic foot 20, a barrier net 30, a jacking cylinder, a scraper plate 50, a hydraulic strut 60, a moving beam 70, and pneumatic claws. After the steel arch frame is erected and before concrete spraying, the main frame 10 is attached to the steel arch frame. The strong magnetic foot 20 is used to attract the main frame 10 to the surface of the steel arch frame. At the same time, the pneumatic claws are activated to grip both sides of the steel arch frame, further fixing it to the steel arch frame. The hydraulic strut 60 is retracted to separate the lower barrier net 302 and the upper barrier net 301. The wet shotcrete machine's robotic arm is moved, and the nozzle is extended into the barrier net 30 for concrete spraying. The upper barrier net 301 and the lower barrier net 302 work together to effectively intercept rebound particles and prevent the fresh layer from falling off. After spraying, the nozzle is removed from the barrier net 30, and the jacking cylinder is activated to push the scraper plate 50 to move repeatedly, smoothing the sprayed concrete. The anti-rebound device is then moved to begin the next cycle.

[0025] The construction method of the anti-rebound device for initial shotcrete in tunnels provided by this utility model is as follows:

[0026] (1) Install and fix the anti-rebound device

[0027] After the steel arch frame and steel mesh are installed, the anti-rebound device is transported to the working face. After checking and confirming that the spacing of the steel arch frame matches the width of the main frame 10, the anti-rebound device is lifted by the robotic arm and its position is adjusted so that the four strong magnetic feet are attracted to the surface of the steel arch frame. At the same time, the pneumatic claws are activated to tightly hold the two sides of the steel arch frame, further fixing the anti-rebound device and preventing it from falling off under the weight during the shotcrete process.

[0028] (2) Shotcrete

[0029] Gently press down the baffle 302 with the nozzle, extending the nozzle inside the baffle 30. The nozzle should be 0.5m-0.8m away from the rock surface, spraying perpendicular to the rock surface. Spray in sections, starting with the center and then the sides, from bottom to top. Make a uniform clockwise circular motion with the nozzle on the rock surface, starting with small circles and gradually increasing the size, with a diameter of 20-30cm. Adjust the air pressure; under normal use, the pressure gauge should read 0.4-0.6 MPa. The accelerator dosage should be controlled at 6%, and the shotcrete thickness can be achieved in one pass.

[0030] (3) Scrape the concrete smooth

[0031] After the concrete spraying is completed, start the jacking cylinder to push the scraper plate 50 to level the sprayed concrete, and repeat the jacking 2 to 3 times.

[0032] (4) Mobile anti-rebound device

[0033] After leveling the concrete, the pneumatic chucks release the steel arch frame, and the robotic arm moves the anti-rebound device to the next spray block to begin the next construction cycle.

[0034] The above are merely preferred embodiments of the present utility model and are not intended to limit the present utility model. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A device for preventing rebound of initial shotcrete in a tunnel, characterized in that, It includes a main frame, strong magnetic feet, barrier net, jacking mechanism, scraper plate and hydraulic support rod. The main frame includes two columns spaced apart from each other and an upper beam, a middle beam and a lower beam respectively connected between the two columns. The upper beam, the middle beam and the lower beam are arranged spaced apart from each other from top to bottom. The number of strong magnetic feet is four, and the four strong magnetic feet are respectively located at the four opposite corners of the main frame; The barrier net includes an upper barrier net and a lower barrier net. The upper barrier net is rotatably connected to the top of the upper beam. The lower barrier net is located below the upper barrier net. The lower barrier net is provided with two sliding channels, and a column passes through each sliding channel. The length of the sliding channel extends along both ends of the lower barrier net on both sides of the main frame. The scraper plate is rotatably connected to one end of the lower baffle, and the end of the lower baffle connected to the scraper plate is located on the same side of the main frame as the strong magnetic foot. The jacking mechanism is located on the middle beam, and the telescopic end of the jacking mechanism is connected to a movable beam. The movable beam is slidably connected between the two columns, and the movable beam is located between the upper beam and the middle beam. The movable beam is connected to the side of the scraper plate facing away from the sprayed rock surface of the tunnel. The two ends of the hydraulic strut are hinged to the lower baffle and the moving beam, respectively, and the hydraulic strut is located on the side of the lower baffle facing away from the sprayed rock surface.

2. The tunnel initial concrete blow prevention device according to claim 1, characterized in that, It also includes a locking mechanism installed on the column, which is used to clamp the steel arch frame.

3. The tunnel initial concrete blow prevention device according to claim 2, characterized in that, The locking mechanism includes pneumatic or manual locking jaws.

4. The anti-rebound device for initial shotcrete in tunnels according to claim 1, characterized in that, The main frame is a rectangular frame structure.

5. The anti-rebound device for initial shotcrete in tunnels according to claim 1, characterized in that, Guide grooves are provided on opposite sides of the two columns, and the two ends of the movable beam are inserted into the guide grooves respectively.

6. The anti-rebound device for initial shotcrete in tunnels according to claim 1, characterized in that, The jacking mechanism is a jacking cylinder. The top of the cylinder body is fixed on the middle beam. The middle beam has a through hole, and the telescopic end of the jacking cylinder is connected to the moving beam through the through hole.

7. The anti-rebound device for initial shotcrete in tunnels according to claim 6, characterized in that, The middle beam has an embedding groove on the side facing the upper beam for the movable beam to be inserted.

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