Movable dust removal device for tunnel reverse slope construction

Abstract

The utility model provides a movable dust exhaust device for tunnel reverse slope construction, which relates to the technical field of tunnel engineering and comprises a wind shield arranged in a tunnel and suitable for dividing the tunnel into a work proceeding area and a work finishing area along the extending direction of the tunnel. An air inlet and an air outlet which are through in the thickness direction are formed in the top of the wind shield; the moving assembly is arranged at the bottom of the wind shield, at least part of the moving assembly is movably arranged in the drainage groove, the moving assembly is provided with a locking part, and the locking part selectively moves towards the groove wall of the drainage groove and abuts against the groove wall of the drainage groove so that the moving assembly and the drainage groove can be fixed. According to the movable dust exhaust device, the position of the wind shield can be rapidly adjusted along with the construction process of a tunnel, the wind shield is prevented from being disassembled and assembled again, the construction efficiency of the tunnel is improved, and the construction cost is reduced.

Description

Technical Field

[0001] This utility model relates to the field of tunnel engineering technology, and more specifically, to a mobile dust removal device for tunnel reverse slope construction. Background Technology

[0002] Tunnel reverse slope construction is a special engineering technique designed for complex geological terrain. Its core characteristic is that the tunnel's axial excavation path is opposite to the original natural slope of the ground. Due to the rising nature of hot air, dust and polluted air accumulate at the tunnel face after blasting in tunnels constructed using reverse slope construction. This is difficult to expel, severely reducing visibility inside the tunnel, endangering personnel health, and increasing construction risks.

[0003] In the existing technology, wooden windbreaks are installed inside the tunnel. The windbreaks have air inlets and outlets, which are used to install air inlet pipes and air outlet pipes, respectively. Both air inlet pipes and air outlet pipes are equipped with jet fans to discharge dust and polluted air. However, the windbreaks cannot be moved. When the tunnel face advances, the windbreaks need to be disassembled and reassembled, which is neither energy-saving nor environmentally friendly, and it also delays the construction period. Utility Model Content

[0004] The purpose of this invention is to provide a mobile dust removal device for tunnel reverse slope construction, thereby improving the aforementioned problems. To achieve this objective, the technical solution adopted by this invention is as follows:

[0005] This application provides a movable dust removal device for tunnel reverse slope construction, comprising: a windbreak plate, which is disposed inside the tunnel and adapted to divide the tunnel into a working area and a working completion area along the tunnel extension direction, the top of the windbreak plate having an air inlet and an air outlet extending in the thickness direction; and a movable component, which is disposed at the bottom of the windbreak plate, at least a portion of which is movably disposed within the drainage trough, and the movable component having a locking part that can selectively move toward and abut against the wall of the drainage trough to fix the movable component to the drainage trough.

[0006] The beneficial effects of this utility model are as follows:

[0007] This invention provides a movable component at the bottom of the windbreak panel, allowing the windbreak panel to move along the extension direction of the drainage channel. Once the windbreak panel reaches the designated position, a movable locking part is used to press against the wall of the drainage channel, thus fixing the position of the windbreak panel. This allows the windbreak panel to be quickly adjusted in position to follow the tunnel construction process, avoiding the need to disassemble and reassemble the windbreak panel, improving tunnel construction efficiency and reducing construction costs.

[0008] According to some embodiments of the present invention, the movable component includes a fixed block and a locking block. The fixed block is connected to the wind baffle, and the locking block is configured as the locking part. The locking block is movably connected to the fixed block, and the fixed block is adapted to move toward and abut against the wall of the drainage trough to fix the fixed block to the drainage trough.

[0009] According to some embodiments of the present invention, the moving component further includes a rotating rod, which is rotatably connected to the fixed block. The outer peripheral wall of the rotating rod is provided with a first thread, and the locking block is provided with an adjustment channel that opens toward the rotating rod. The inner peripheral wall of the adjustment channel is provided with a second thread, and the first thread and the second thread cooperate.

[0010] According to some embodiments of the present invention, the fixing block is provided with a moving channel that opens toward the locking block, and a portion of the locking block is movably disposed within the moving channel.

[0011] According to some embodiments of the present invention, the movable component further includes a caster wheel, which is rotatably disposed at the bottom of the fixed block and is adapted to contact the bottom wall of the drainage trough.

[0012] According to some embodiments of the present invention, one drainage trough corresponds to two of the moving components, and the locking blocks of the two moving components move away from each other to abut against the two walls of the drainage trough.

[0013] According to some embodiments of the present invention, an inflatable cushion is also included, which is disposed between the windbreak and the inner wall of the tunnel, and the inflatable cushion is adapted to fill the gap between the windbreak and the tunnel.

[0014] According to some embodiments of the present invention, the inflatable cushion includes multiple cushions, which are spaced apart along the thickness direction of the windbreak plate; wherein the side of the inflatable cushion facing the inner wall of the tunnel is provided with anti-puncture material.

[0015] According to some embodiments of the present invention, it further includes an atomizing tube, which is disposed on the side of the wind deflector facing the working area. The atomizing tube is disposed around at least a portion of the outer periphery of the wind deflector and is adapted to spray water mist toward the working area.

[0016] According to some embodiments of the present invention, the windbreak is provided with a safety opening extending through in the thickness direction, and the windbreak is rotatably connected to a passage door.

[0017] Other features and advantages of this invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing embodiments of the invention. The objects and other advantages of this invention can be realized and obtained by means of the structures particularly pointed out in the written description, claims, and drawings. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the structure of the portable dust removal device of this utility model;

[0020] Figure 2 for Figure 1 A magnified view of A in the center circle;

[0021] Figure 3 This is a cross-sectional view showing the cooperation between the fixing block and the locking block of this utility model.

[0022] Figure 4 This is a schematic diagram of the structure of the universal wheel of this utility model;

[0023] Figure 5 This is a schematic diagram of the passage gate of this utility model.

[0024] Marked in the diagram: 1. Portable dust removal device;

[0025] 10. Wind deflector; 11. Air inlet; 12. Air outlet;

[0026] 20. Moving component; 21. Fixed block; 211. Moving channel; 22. Locking block; 221. Adjusting channel; 23. Rotating rod; 24. Caster wheel;

[0027] 30. Inflatable cushion; 40. Atomizing tube; 50. Passage door. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. The components of the embodiments of this utility model described and shown in the accompanying drawings can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this utility model provided in the accompanying drawings is not intended to limit the scope of the claimed utility model, but merely to illustrate selected embodiments of the utility model. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model without inventive effort are within the scope of protection of this utility model.

[0029] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, in the description of this utility model, terms such as "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0030] like Figures 1-5 As shown, this embodiment provides a movable dust removal device 1 for tunnel reverse slope construction. A drainage ditch is provided on the tunnel floor, and the extension direction of the drainage ditch is parallel to the extension direction of the tunnel. The movable dust removal device 1 includes: a wind baffle 10 and a moving component 20. The wind baffle 10 is disposed in the tunnel and is adapted to divide the tunnel into a working area and a working completion area along the extension direction of the tunnel. The top of the wind baffle 10 is provided with an air inlet 11 and an air outlet 12 that pass through in the thickness direction. The moving component 20 is disposed at the bottom of the wind baffle 10. At least a portion of the moving component 20 is movably disposed in the drainage ditch, and the moving component 20 has a locking part that can selectively move toward the wall of the drainage ditch and abut against it to fix the moving component 20 to the drainage ditch.

[0031] In some embodiments, a wind deflector 10 is disposed inside the tunnel, which can divide the tunnel into two areas along the tunnel's extension direction: a working area (the area where work is being carried out, i.e., the tunnel face) and a completed area (the area where work has been completed). This helps control the spread of dust and harmful gases and protects the completed work area from newly generated contamination.

[0032] Air inlets 11 and 12 are located at the top of the baffle plate 10 and extend through the entire baffle plate 10 in the thickness direction. The purpose of the air inlets 11 and 12 is to promote air circulation and help expel dust and polluted air generated during construction. Of course, air inlets 11 and 12 can also be used to fix air inlet and outlet ducts, respectively. Both air inlet and outlet ducts are equipped with jet fans to accelerate air circulation within the work area, thereby ensuring air clarity and visibility within the work area.

[0033] The movable component 20 is installed at the bottom of the wind deflector 10, and at least a portion of the movable component 20 is movably disposed within the drainage trough, meaning that the movable component 20 can move along the drainage trough on the tunnel floor. The movable component 20 is provided with a locking part, which can move toward and abut against the wall of the drainage trough as needed, thereby firmly fixing the movable component 20 within the drainage trough, and thus fixing the position of the wind deflector 10.

[0034] Understandably, by combining the wind deflector 10 with the drainage channel inside the tunnel, the drainage channel is used as a track to guide and support the movement of the wind deflector 10. Thus, the wind deflector 10 can be quickly and easily adjusted in position without disassembly.

[0035] As tunnel construction progresses, workers can move the windbreak 10. Once the windbreak 10 is pushed to the designated position, the locking part can be moved and pressed against the wall of the drainage channel to ensure that the relative position of the windbreak 10 and the drainage channel is fixed. This avoids the need to disassemble and reassemble the windbreak 10, improves tunnel construction efficiency, and prevents damage to the windbreak wall during disassembly and reassembly, thus reducing construction costs.

[0036] According to the present invention, a movable dust removal device for tunnel reverse slope construction is provided. By setting a movable component 20 at the bottom of the windbreak plate 10, the windbreak plate 10 can be moved along the extension direction of the drainage channel by the movable component 20. After the windbreak plate 10 moves to the designated position, the position of the windbreak plate 10 is fixed by moving the locking part and making the locking part abut against the channel wall of the drainage channel. This allows the windbreak plate 10 to be quickly adjusted in position according to the tunnel construction process, avoiding the need to disassemble and reassemble the windbreak plate 10, improving the tunnel construction efficiency and reducing construction costs.

[0037] According to some embodiments of the present invention, the movable component 20 includes a fixed block 21 and a locking block 22. The fixed block 21 is connected to the wind baffle 10, and the locking block 22 is configured as a locking part. The locking block 22 is movably connected to the fixed block 21. The fixed block 21 is adapted to move toward the wall of the drainage trough and press against it to fix the fixed block 21 to the drainage trough.

[0038] In some embodiments, a fixing block 21 is provided at the bottom of the wind deflector 10, the fixing block 21 extends into the drainage channel, and a locking block 22 is provided between the fixing block 21 and the channel wall of the drainage channel. The locking block 22 is movably connected to the fixing block 21, and the locking block 22 moves toward the channel wall of the drainage channel and abuts against it, so as to achieve the locking effect by applying pressure to the channel wall of the drainage channel (the greater the pressure between the locking block 22 and the channel wall of the drainage channel, the greater the friction between the locking block 22 and the channel wall of the drainage channel, thereby preventing the locking block 22 from sliding relative to the drainage channel in the extension direction of the drainage channel, thereby ensuring the positional stability of the moving component 20, and thus ensuring the positional stability of the wind deflector 10).

[0039] Thus, after the wind deflector 10 is pushed to the desired new position, the locking block 22 moves toward and presses against the wall of the drainage channel to apply pressure to the wall of the drainage channel, thereby increasing the friction between the moving component 20 and the wall of the drainage channel, thereby preventing the moving component 20 from sliding relative to the drainage channel, thereby fixing the position of the wind deflector 10.

[0040] According to some embodiments of the present invention, the moving component 20 further includes a rotating rod 23, which is rotatably connected to the fixed block 21. The outer peripheral wall of the rotating rod 23 is provided with a first thread, and the locking block 22 is provided with an adjustment channel 221 that opens toward the rotating rod 23. The inner peripheral wall of the adjustment channel 221 is provided with a second thread, and the first thread and the second thread cooperate.

[0041] In some embodiments, the rotating rod 23 extends in the direction from one wall of the drainage channel to another wall of the drainage channel. The rotating rod 23 is rotatably connected to the fixed block 21. One end of the rotating rod 23 is located between the fixed block 21 and one wall of the drainage channel, and the other end of the rotating rod 23 is located between the fixed block 21 and another wall of the drainage channel. The outer peripheral wall of the rotating rod 23 is provided with a first thread. The locking block 22 is located between the fixed block 21 and another wall of the drainage channel. The inner peripheral wall of the adjustment channel 221 of the locking block 22 is provided with a second thread, and the first thread and the second thread cooperate.

[0042] Therefore, after the baffle plate 10 moves to the designated position, the construction personnel can rotate the rotating rod 23 to drive the locking block 22 to move towards the other wall of the drainage trough until the locking block 22 is pressed against the other wall of the drainage trough. The locking method of the moving component 20 is simple; it can be locked or unlocked simply by rotating the rotating rod 23, which improves the ease of use of the movable dust removal device 1.

[0043] According to some embodiments of the present invention, the fixing block 21 is provided with a moving channel 211 that opens toward the locking block 22, and a portion of the locking block 22 is movably disposed within the moving channel 211.

[0044] In some embodiments, the locking block 22 is provided with a sliding protrusion on the side facing the fixing block 21. Part of the sliding protrusion is movably disposed in the moving channel 211. The extending direction of the moving channel 211 is parallel to the extending direction of the rotating rod 23. The inner peripheral wall of the moving channel 211 can restrict the outer peripheral wall of the sliding protrusion, so that the sliding protrusion can move stably along the extending direction of the moving channel 211, thereby allowing the locking block 22 to move stably toward the wall of the drainage trough.

[0045] It is worth mentioning that the cross-sectional structure of the moving channel 211 is polygonal, and the cross-section of the sliding protrusion corresponds to the cross-section of the moving channel 211. Thus, the inner peripheral wall of the moving channel 211 can restrict the outer peripheral wall of the sliding protrusion, thereby preventing the sliding protrusion from rotating relative to the moving channel 211 in the circumferential direction. This ensures that the rotation of the rotating rod 23 can stably drive the locking block 22 to move toward or away from the wall of the drainage channel.

[0046] According to some embodiments of the present invention, the movable component 20 further includes a caster wheel 24, which is rotatably disposed at the bottom of the fixed block 21 and is adapted to contact the bottom wall of the drainage trough.

[0047] In some embodiments, the addition of casters 24 can reduce the friction of the wind deflector 10 when it moves in the drainage channel, making the movement of the wind deflector 10 easier. Even in long tunnels, construction workers can easily push the wind deflector 10 without expending a lot of physical strength.

[0048] Moreover, the multi-directional rotation capability of the casters 24 allows the wind deflector 10 to be flexibly adjusted during movement to adapt to the complex terrain or construction needs that may exist in the tunnel. At the same time, during movement, the casters 24 are always in contact with the bottom wall of the drainage ditch, providing stable support for the wind deflector 10 and avoiding shaking or tilting caused by uneven ground or other factors.

[0049] It is worth mentioning that the caster wheel 24 is equipped with a rotatable locking plate. The rotation of the locking plate can cooperate with the roller of the caster wheel 24 to prevent the roller from continuing to rotate. Thus, when the caster wheel 24 is in the locked state, the caster wheel 24 can work together with the locking block 22 to ensure the stability of the wind deflector 10.

[0050] According to some embodiments of the present invention, one drainage trough corresponds to two moving components 20, and the locking blocks 22 of the two moving components 20 move away from each other to abut against the two walls of the drainage trough.

[0051] In some embodiments, one drainage trough corresponds to two moving components 20. After the baffle plate 10 moves to the designated position, the locking blocks 22 of the two moving components 20 abut against the two walls of the drainage trough respectively, which can further increase the friction between the movable dust removal device 1 and the drainage trough, thereby further improving the position fixing effect of the baffle plate 10.

[0052] It is worth mentioning that a tunnel can be equipped with multiple drainage channels. The mobile dust removal device 1 of this application is equipped with multiple moving components 20, and each drainage channel corresponds to two moving components 20.

[0053] According to some embodiments of the present invention, the movable dust removal device 1 further includes an air cushion 30, which is disposed between the wind baffle 10 and the inner wall of the tunnel, and is adapted to fill the gap between the wind baffle 10 and the tunnel.

[0054] In some embodiments, the inflated air cushion 30 can fill the gap between the windbreak 10 and the tunnel to prevent dust and dirty air from leaking from the gap between the windbreak 10 and the inner wall of the tunnel, thereby improving the sealing performance of the portable dust removal device 1.

[0055] It is worth mentioning that after the windbreak 10 is moved to the designated position, the construction workers inflate the air cushion 30. As the air cushion 30 expands, it fits tightly against the edge of the windbreak 10 and the inner wall of the tunnel to form an effective sealing layer. Moreover, the air cushion 30 can be adjusted according to different tunnel shapes and sizes. That is, by controlling the inflation amount, it can adapt to various irregular tunnel inner walls to ensure the best sealing effect.

[0056] Of course, when it is necessary to reposition the wind deflector 10, simply release the air from the air cushion 30 to easily move the wind deflector 10, so that the movable dust removal device 1 maintains good sealing while retaining its mobility.

[0057] According to some embodiments of the present invention, the inflatable cushion 30 includes a plurality of inflatable cushions 30, which are distributed at intervals along the thickness direction of the windbreak plate 10; wherein the side of the inflatable cushion 30 facing the inner wall of the tunnel is provided with anti-puncture material.

[0058] In some embodiments, each air cushion 30 can form a seal, thereby the multiple air cushions 30 are spaced apart along the thickness direction of the baffle plate 10 to form a multi-layer seal between the working area and the working area, thus ensuring the isolation effect between the working area and the working area.

[0059] It is worth mentioning that the side of the air cushion 30 facing the inner wall of the tunnel is provided with puncture-resistant material, which can be butyl rubber. This reduces the risk of the air cushion 30 being punctured by lining burrs. Furthermore, since the portable dust removal device 1 of this application is provided with multiple layers of air cushions 30, even if one or more air cushions 30 are punctured, good isolation can still be formed between the working area and the working area, improving the safety redundancy of the portable dust removal device 1.

[0060] It should be noted that the puncture-resistant material enhances the durability of the air cushion 30. Moreover, compared to a single large-area air cushion 30, multiple small air cushions 30 can be selectively inflated or deflated according to actual conditions, making them more energy-efficient and convenient for local maintenance or replacement.

[0061] According to some embodiments of the present invention, the movable dust removal device 1 further includes an atomizing tube 40, which is disposed on the side of the baffle plate 10 facing the working area. The atomizing tube 40 is arranged around at least a portion of the outer periphery of the baffle plate 10 and is adapted to spray water mist toward the working area.

[0062] In some embodiments, when it is necessary to control dust at the construction site, the atomization system is activated. At this time, the atomization pipe 40 begins to spray fine water mist into the work area. The tiny water droplets in the water mist come into contact with and combine with dust particles in the air, increasing the mass and volume of the dust particles. This makes the dust particles more likely to be affected by gravity and fall to the ground instead of remaining suspended in the air, thereby effectively reducing the amount of dust floating in the air and providing a cleaner working environment, which helps prevent occupational diseases (such as pneumoconiosis).

[0063] It is worth mentioning that reducing dust in the air can also improve visibility inside the tunnel, allowing construction workers to see the work area more clearly, thereby improving work efficiency and safety.

[0064] According to some embodiments of the present invention, the wind deflector 10 is provided with a safety opening that extends through in the thickness direction, and the wind deflector 10 is rotatably connected to a passage door 50.

[0065] In some embodiments, the access door 50 rotates to selectively open or close the safety opening. When passage through the safety opening is not required, the access door 50 is closed, forming a complete barrier to prevent dust and harmful gases from spreading from the work area to the work completion area. When it is necessary for construction personnel or small equipment to pass through, the operator can open the safety opening by rotating the access door 50.

[0066] Therefore, the presence of the safety opening allows construction workers to easily enter and exit different areas without having to walk around the entire windbreak 10, improving work efficiency and reducing unnecessary travel distance. Preferably, the access door 50 is equipped with a safety lock, which can fix the position between the access door 50 and the windbreak 10, thereby preventing the access door 50 from rotating in case of accident.

[0067] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

[0068] The above description is merely a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this utility model should be included within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the scope of the claims.

Claims

1. A mobile dust removal device for tunnel reverse slope construction, wherein a drainage ditch is provided on the tunnel floor, the extension direction of the drainage ditch being parallel to the extension direction of the tunnel, characterized in that, include: A wind deflector (10) is provided in the tunnel and is adapted to divide the tunnel into a working area and a working area along the tunnel extension direction. The top of the wind deflector (10) is provided with an air inlet (11) and an air outlet (12) that are through in the thickness direction. A movable component (20) is disposed at the bottom of the wind deflector (10), at least a portion of which is movably disposed within the drainage trough, and the movable component (20) has a locking part which can selectively move toward and abut against the wall of the drainage trough to fix the movable component (20) to the drainage trough.

2. The mobile dust removal device for tunnel reverse slope construction according to claim 1, characterized in that, The movable component (20) includes a fixed block (21) and a locking block (22). The fixed block (21) is connected to the wind deflector (10). The locking block (22) is configured as the locking part. The locking block (22) is movably connected to the fixed block (21). The fixed block (21) is adapted to move toward and abut against the wall of the drainage channel to fix the fixed block (21) to the drainage channel.

3. The mobile dust removal device for tunnel reverse slope construction according to claim 2, characterized in that, The moving component (20) also includes a rotating rod (23), which is rotatably connected to the fixed block (21). The outer peripheral wall of the rotating rod (23) is provided with a first thread, and the locking block (22) is provided with an adjustment channel (221) that opens toward the rotating rod (23). The inner peripheral wall of the adjustment channel (221) is provided with a second thread, and the first thread and the second thread cooperate.

4. The mobile dust removal device for tunnel reverse slope construction according to claim 3, characterized in that, The fixing block (21) is provided with a moving channel (211) that opens toward the locking block (22), and a portion of the locking block (22) is movably disposed within the moving channel (211).

5. The mobile dust removal device for tunnel reverse slope construction according to claim 4, characterized in that, The moving component (20) also includes casters (24) which are rotatably disposed at the bottom of the fixed block (21) and are adapted to contact the bottom wall of the drainage channel.

6. The mobile dust removal device for tunnel reverse slope construction according to claim 4, characterized in that, One drainage channel corresponds to two of the moving components (20), and the locking blocks (22) of the two moving components (20) move away from each other to abut against the two walls of the drainage channel.

7. The mobile dust removal device for tunnel reverse slope construction according to claim 1, characterized in that, It also includes an inflatable cushion (30) disposed between the wind deflector (10) and the inner wall of the tunnel, the inflatable cushion (30) being adapted to fill the gap between the wind deflector (10) and the tunnel.

8. The mobile dust removal device for tunnel reverse slope construction according to claim 7, characterized in that, The inflatable cushion (30) comprises a plurality of cushions, which are spaced apart along the thickness direction of the windbreak plate (10); wherein The inflatable cushion (30) is provided with puncture-resistant material on the side facing the inner wall of the tunnel.

9. The mobile dust removal device for tunnel reverse slope construction according to claim 1, characterized in that, It also includes an atomizing tube (40), which is disposed on the side of the wind deflector (10) facing the working area. The atomizing tube (40) is disposed around at least a portion of the outer periphery of the wind deflector (10) and is adapted to spray water mist toward the working area.

10. The mobile dust removal device for tunnel reverse slope construction according to claim 1, characterized in that, The wind deflector (10) is provided with a safety opening that extends through in the thickness direction, and the wind deflector (10) is rotatably connected to a passage door (50).

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