Long tunnel roadway type ventilation bridge system and construction method thereof

Abstract

The invention discloses a long tunnel roadway type ventilation air bridge system which is suitable for parallel excavation of a parallel adit and a main tunnel, a first transverse tunnel is communicated with the parallel adit and the main tunnel, the ventilation air bridge system is located in the intersection area of the first transverse tunnel and the parallel adit and comprises an air bridge body, the air bridge body comprises a main frame, an air bridge partition wall and a bridge deck, and the bridge deck is horizontally erected on the upper portion of the main frame. The main frame covers an area enclosed by the main frame; the bridge deck slabs divide the intersection area into an upper section and a lower section; the upper section is a fresh air supply channel; in the upper section, the two ends, located in the first transverse hole, of the bridge deck slab are closed, and the two ends, located in the parallel adit, of the bridge deck slab are open; in the lower section, air bridge partition walls are arranged at the two ends, located at the parallel guide, of the bridge deck slab; and in the lower section, the two ends of the first transverse hole are open, are communicated with the first transverse hole, and are used as dirty air and vehicle passages. By means of the air bridge system, roadway type ventilation can be adopted after the transverse tunnel, the parallel adit and the main tunnel are communicated, and the excavation progress is ensured.

Description

Technical Field

[0001] This invention belongs to the field of tunnel construction ventilation technology, specifically relating to a ventilation bridge system for long tunnels and its construction method. Background Technology

[0002] During tunnel construction, after the cross passage and pilot tunnel are connected, the long distance between the pilot tunnel and the pilot tunnel necessitates the use of tunnel-type ventilation to alleviate ventilation pressure. As excavation continues on both working faces, the polluted air discharged from the cross passage will enter the pilot tunnel and contaminate its working face, affecting the excavation progress. Currently, two axial flow fans are placed at the entrance of the pilot tunnel, using forced ventilation. However, this method has two drawbacks: firstly, the long ventilation distance requires high-power axial flow fans, resulting in high energy consumption; secondly, it causes cross-contamination of airflow from multiple working faces. Summary of the Invention

[0003] The purpose of this invention is to provide a long tunnel roadway ventilation bridge system and its construction method, which enables roadway ventilation to be used after the cross passage, pilot tunnel and main tunnel are connected, thus ensuring the excavation progress.

[0004] This invention adopts the following technical solution: a ventilation bridge system for long tunnels, suitable for parallel excavation of pilot tunnels and main tunnels, wherein the first transverse tunnel connects the pilot tunnel and the main tunnel, and is located in the intersection area of ​​the first transverse tunnel and the pilot tunnel, including a ventilation bridge body, the ventilation bridge body including a main frame, ventilation bridge partition walls and bridge deck, wherein: The main frame is a four-column support frame, with the four columns standing vertically at the four corners of the intersection area of ​​the first horizontal opening and the guide rail. The bridge deck is horizontally installed on top of the main frame and covers the area enclosed by the main frame; the bridge deck divides the intersection area into upper and lower sections. The upper section is a fresh gas supply channel; in the upper section, the bridge deck is closed at both ends of the first transverse opening, and open at both ends of the horizontal guide. In the lower section, wind bridge partitions are installed at both ends of the bridge deck and the upper end of the wind bridge partitions are connected to the upper end of the bridge deck. In the lower section, the two ends of the first cross opening are open and connected to the first cross opening, serving as a passage for sewage and vehicles. The wind bridge partitions are constructed of brick and cement mortar.

[0005] Furthermore, a duct is installed in the upper section. The duct runs along the direction of the transverse tunnel. Both ends of the duct pass through the blocking plates at their respective ends. One end of the duct is located at the entrance of the first transverse tunnel and is connected to the first fan located outside the first transverse tunnel. The other end extends to the working face inside the main tunnel and is used to supply fresh air to the working face of the main tunnel.

[0006] Furthermore, the outer side of the wind bridge partition wall is an arc shape extending outward from top to bottom.

[0007] Furthermore, the bridge deck is covered with horizontal concrete walls, the sidewalls of which are tightly fitted to the tunnel interior walls.

[0008] Furthermore, a second fan is installed inside the guide tube, in front of the wind bridge body, and behind the second transverse tunnel. The second fan is used to supply air to the working face in front of the guide tube and the working face in front of the main tunnel.

[0009] Furthermore, a crossbeam connects two adjacent columns, and a horizontal secondary beam connects two diagonally opposite columns.

[0010] Furthermore, a third fan is installed at the inlet end of the guide tube to supply air into the guide tube, and the air is transported through the upper section to the guide tube in front of the wind bridge body.

[0011] Furthermore, a fourth ventilation fan is installed at the entrance of the main tunnel, which is used to supply air to the first working face being excavated in the forward direction inside the main tunnel.

[0012] This invention also discloses a construction method for a long tunnel ventilation bridge system, characterized by comprising the following steps: Step 1: The pilot tunnel and the main tunnel are excavated in parallel. A third ventilation fan is installed at the entrance of the pilot tunnel and a fourth ventilation fan is installed at the entrance of the main tunnel. Before the tunnel excavation reaches the intersection of the first cross tunnel and the pilot tunnel, the installation position of the main frame is determined according to the design. The intersection area is excavated and the main frame is installed at the designed position. Step 2: Lay bridge deck panels on the main frame, specifically in the intersection area; Step 3: In the lower section, at both ends of the pilot tunnel located on the bridge deck, the wind bridge partition wall is constructed using ordinary bricks and M7.5 cement mortar, and the sidewall of the wall is in close contact with the initial support surface of the tunnel. In the upper section, a horizontal wall is built on the bridge deck; in the upper section, and at both ends of the first transverse opening, a blocking plate is built, and a ventilation duct through hole is reserved on the blocking plate. Step 4: Install the duct along the direction of the first horizontal opening, with both ends passing through the corresponding duct exit holes; The first fan is connected to the entrance end of the first horizontal opening of the air duct; a second fan is installed inside the flat guide, on the air outlet side of the air bridge body, and behind the second horizontal opening. Excavation proceeds in both directions from the first transverse tunnel to the main tunnel, forming two working faces. The first ventilation fan supplies air to the two working faces inside the main tunnel. Excavation proceeds in both directions from the second transverse tunnel to the main tunnel, forming two working faces. The second ventilation fan supplies air to the working face in front of the horizontal guide and to the two working faces inside the main tunnel.

[0013] The beneficial effects of this invention are: 1. By using the wind bridge body, an independent fresh air supply channel is formed, achieving complete isolation between fresh air and polluted air, and eliminating cross-contamination. 2. The main frame serves as a support, ensuring structural stability; the wind bridge partition walls are constructed with bricks and cement mortar, providing good sealing and a long service life. 3. The sidewalls of the wind bridge partition walls away from the cross-traffic area are arc-shaped and extend downwards towards the direction away from the cross-traffic area, reducing wind resistance. 4. By setting up the wind bridge body within the guide vane and installing a second fan behind the wind bridge body, tunnel-like ventilation can be formed in the guide vane direction, shortening the ventilation distance and saving on ductwork and electricity costs for ventilation during construction; it also meets the needs of simultaneous construction on multiple work surfaces, improving tunnel construction progress and saving construction time. Attached Figure Description

[0014] Figure 1 A schematic diagram showing the installation location of a ventilation air bridge system for long tunnels; Figure 2 Schematic diagram of a ventilation bridge system for long tunnels; Figure 3 This is a schematic diagram of the longitudinal section of the transverse tunnel; The components are: 1. Wind bridge body; 1-1. Horizontal guide; 1-2. Main tunnel; 1-3. First horizontal tunnel; 1-4. Second horizontal tunnel; 1-5. First fan; 1-6. Third fan; 1-7. Fourth fan; 1-8. Second fan; 2. Main frame; 3. Wind bridge partition wall; 4. Bridge deck; 5. Horizontal wall; 6. Barrier upright; 7. Air duct. Detailed Implementation

[0015] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0016] This invention discloses a ventilation bridge system for long tunnels, suitable for use in long tunnels, i.e., tunnels longer than 4 kilometers, such as... Figure 1 , 2 As shown in Figure 3, the pilot tunnel 1-1 and the main tunnel 1-2 are excavated in parallel, and the first transverse tunnel 1-3 has connected the pilot tunnel 1-1 and the main tunnel 1-2. It is located in the intersection area of ​​the first transverse tunnel 1-3 and the pilot tunnel 1-1, and includes the wind bridge body 1. The wind bridge body 1 includes the main frame 2, the wind bridge partition wall 3, and the bridge deck 4, wherein: the transverse tunnel has connected the pilot tunnel 1-1 and the main tunnel 1-2, and it is located in the intersection area of ​​the first transverse tunnel 1-3 and the pilot tunnel 1-1. It includes the wind bridge body 1, the wind bridge body 1 includes the main frame 2, the wind bridge partition wall 3, the bridge deck 4, and the horizontal wall 5, wherein: The main frame 2 is a four-column support frame. The four columns are erected vertically at the four corners of the intersection area of ​​the first horizontal opening 1-3 and the horizontal guide 1-1. The upper end of the column is at the designed height, based on the direction of the vehicle traveling below.

[0017] Bridge deck 4 is horizontally erected on the upper part of the main frame 2 and covers the area enclosed by the main frame 2; bridge deck 4 divides the intersection area into upper and lower sections. In the upper section, the bridge deck 4 is closed at both ends of the first transverse tunnel 1-3, and open at both ends of the guide tunnel 1-1. A blocking plate 6 is installed at both ends of the bridge deck 4 at the first transverse tunnel 1-3, with the sidewalls of the blocking plate 6 tightly fitted to the inner wall of the tunnel. In the upper section, a ventilation duct 7 is installed, running along the direction of the transverse tunnel. Both ends of the duct pass through the blocking plate 6 at their respective ends. One end of the duct 7 is located at the entrance of the first transverse tunnel 1-3, connecting to the first fan 1-5 located outside the first transverse tunnel 1-3; the other end extends to the working face inside the main tunnel 1-2, used to supply fresh air to the working face of the main tunnel 1-2.

[0018] In the lower section, wind bridge partitions 3 are installed at both ends of the bridge deck 4 at 1-1. The upper end of the wind bridge partition 3 is connected to the upper end of the bridge deck 4, and its outer side is an arc extending outward from top to bottom. In the lower section, the two ends of the first cross opening 1-3 are open and connected to the first cross opening 1-3, serving as a vehicle passage.

[0019] Horizontal wall 5, made of concrete, is formed by pouring concrete onto bridge deck 4 and allowing it to solidify. The sidewalls of horizontal wall 5 are tightly fitted to the tunnel interior wall.

[0020] Inside the horizontal guide 1-1, a second fan 1-8 is located in front of the wind bridge body 1 and behind the second transverse tunnel 1-4. The second fan 1-8 is used to supply air to the working face in front of the horizontal guide 1-1 and the working face in front of the main tunnel 1-2. The second transverse tunnel 1-4 serves as a return air and transportation channel.

[0021] A third fan 1-6 is installed at the inlet end of the guide 1-1 to supply air into the guide 1-1 and to transport it through the upper section to the guide 1-1 in front of the wind bridge body 1.

[0022] A fourth ventilation fan 1-7 is installed at the entrance of the main tunnel 1-2. The fourth ventilation fan 1-7 is used to supply air to the first working face of the forward excavation inside the main tunnel 1-2.

[0023] This invention also discloses a construction method for a long tunnel ventilation bridge system, which includes the following steps: Step 1: The pilot tunnel 1-1 and the main tunnel 1-2 are excavated in parallel. A third ventilation fan 1-6 is installed at the entrance of the pilot tunnel 1-1, and a fourth ventilation fan 1-7 is installed at the entrance of the main tunnel 1-2. Before the tunnel excavation reaches the intersection of the first cross tunnel 1-3 and the pilot tunnel 1-1, the excavation work is suspended, the intersection area is cleared, and the working face is ensured to be flat and stable.

[0024] Using a total station, the outline of the wind bridge and the foundation center point of the main frame 2 in the design drawings were accurately measured and calibrated. Key control lines and elevations were marked on the tunnel floor and sidewalls to ensure that the wind bridge body 1 matches the tunnel design axis and slope, and to avoid reduced ventilation effect or structural interference due to positional deviation.

[0025] At the marked pre-installed column locations, excavate to the design depth and inspect the trench to ensure the foundation is solid. Then, erect formwork and pour C25 or higher grade concrete for the foundation. Before the foundation concrete initially sets, precisely install the embedded anchor plates, adjusting their top surface elevation to the design height and maintaining them level. This provides a robust and level load-bearing foundation for the installation of the main frame 2. The embedded anchor plates effectively transfer the load of the upper main frame 2 to the foundation and prevent displacement of the main frame 2 through anchoring, ensuring the stability of the overall structure.

[0026] Prefabricated steel beams, secondary beams, and columns were transported to the construction site. The installation sequence was as follows: columns were erected first, followed by beams to form the main frame. Then, secondary beams and connectors were installed. Columns were erected at the four corners of the intersection of the first horizontal opening 1-3 and the guide rail 1-1. Beams were then installed between adjacent columns. Secondary beams were then installed between two diagonally opposite columns. Connections were initially secured with high-strength bolts, followed by full welding for reinforcement. This combination of high-strength bolts and welding ensured the rigidity and strength of the joints, enabling them to withstand ventilation dynamics and accidental impact loads. Throughout the process, the verticality of the columns and the elevation of the beams were monitored in real time using a theodolite and level to ensure that the verticality deviation was less than 10mm and the elevation met design specifications.

[0027] Step 2: Lay a 5mm thick steel plate as the bridge deck 4 on the main frame 2. After the steel plate is laid flat, continuously weld it to all the steel frame components in contact below. The weld should be uniform, full, free of slag inclusions and incomplete welds. The bridge deck 4 serves as a load-bearing partition separating the intersection area, dividing the intersection area into upper and lower sections; it also bears the load of the upper section and safely transfers it to the main frame 2. Full welding not only ensures structural strength but also forms a preliminary airtight isolation layer between the steel plate and the main frame 2, laying the foundation for subsequent sealing work. The bridge deck 4 extends from both ends of the guide rail 1-1 into the intersection area.

[0028] Step 3: In the lower section, at both ends of the guide rail 1-1 located on the bridge deck 4, construct the wind bridge partition wall 3 using ordinary bricks and M7.5 cement mortar. During construction, ensure that the wall is in close contact with the initial support surface of the tunnel, and strictly control the verticality and horizontality of the wall and its top surface using a plumb line and spirit level. Pre-embed φ6 short steel bars at the top of the wind bridge partition wall 3, ensuring that the exposed part is reliably welded to the upper bridge deck 4. Finally, fill the gap between the top of the wall and the bridge deck with M10 cement mortar.

[0029] In the upper section, a horizontal wall 5 is constructed on the bridge deck 4 using ordinary bricks and M7.5 cement mortar. In the upper section, and at both ends of the first transverse tunnel 1-3, blocking slabs 6 are constructed, with pre-drilled holes for ventilation ducts. In the upper section, and within the horizontal guide 1-1, sidewalls are constructed using MU10 sintered ordinary bricks and M7.5 cement mortar, ensuring close contact between the sidewalls and the initial tunnel support surfaces. The wind bridge partition wall 3, the blocking slabs 6, and the tunnel inner wall together form a closed ventilation duct boundary. The function of the ventilation duct is to guide airflow and prevent cross-ventilation.

[0030] Use quick-drying cement or expanding cement mortar to seal large gaps between the brickwork and the irregular initial support surface of the tunnel. Then, apply polyurethane foam evenly and comprehensively to all possible air leakage points, including joints between steel plates, welds between the bridge deck and the frame, and joints between the wall top and the bridge deck. The foam should fully fill the gaps and form a flexible sealing layer after natural curing. This completely blocks the path of mutual penetration between fresh and stale air through structural joints, and the multi-layer sealing treatment effectively adapts to minor deformations and vibrations within the tunnel. After the masonry is completed, perform water spraying and moisturizing curing for no less than 7 days to prevent mortar cracking.

[0031] Step 4: Install the duct 7 along the direction of the first horizontal opening 1-3, with both ends passing through the corresponding duct outlet holes, and seal them with rubber and concrete.

[0032] Start the third fan 1-6 located at the inlet of guide vane 1-1, initially at low speed and gradually increasing to normal operating conditions. Observe the air bridge body 1 for any abnormal vibrations or noises during the operation of the third fan 1-6. Finally, using a calibrated anemometer, measure the wind speed at fixed sections upstream and downstream of the air bridge body 1, and calculate the actual air leakage rate of the system based on the airflow difference. Verify the performance of the air bridge body 1 under actual working conditions. Observing vibration is to assess whether the structural dynamic response is normal. Measuring the air leakage rate is the core indicator for ultimately verifying the sealing effect and ventilation efficiency of the air bridge, ensuring that it is less than the design requirement of 2%, proving that the air bridge body 1 has been successfully put into operation. The upstream side is the air inlet side, and the downstream side is the air outlet side.

[0033] Excavation proceeds in both directions from the first transverse tunnel 1-3 to the main tunnel 1-2, forming two working faces. The first ventilation fan 1-5 supplies air to the two working faces in the main tunnel 1-2. Excavation proceeds in both directions from the second transverse tunnel 1-4 to the main tunnel 1-2, forming two working faces. The second ventilation fan 1-8 supplies air to the working face in front of the horizontal guide 1-1 and the two working faces in the main tunnel 1-2.

Claims

1. A ventilation bridge system for long tunnels, characterized in that, Suitable for parallel excavation of the pilot tunnel (1-1) and the main tunnel (1-2), and the first transverse tunnel (1-3) is connected to the pilot tunnel (1-1) and the main tunnel (1-2). It is located in the intersection area of ​​the first transverse tunnel (1-3) and the pilot tunnel (1-1), including the wind bridge body (1). The wind bridge body (1) includes a main frame (2), a wind bridge partition wall (3), and a bridge deck (4), wherein: The main frame (2) is a four-column support frame, with the four columns standing vertically at the four corners of the intersection area of ​​the first horizontal hole (1-3) and the horizontal guide (1-1); The bridge deck (4) is horizontally erected on the upper part of the main frame (2) and covers the area enclosed by the main frame (2); the bridge deck (4) divides the intersection area into upper and lower sections; The upper section is a fresh gas supply channel; in the upper section, the two ends of the bridge deck (4) located at the first transverse hole (1-3) are closed, and the two ends of the flat guide (1-1) are open. In the lower section, the bridge deck (4) is provided with wind bridge partitions (3) at both ends of the (1-1) flat guide (1-1), and the upper end of the wind bridge partitions (3) is connected to the upper end of the bridge deck (4); in the lower section, the two ends of the first transverse opening (1-3) are open and connected to the first transverse opening (1-3) to serve as a passage for sewage and vehicles; the wind bridge partitions (3) are made of brick masonry and cement mortar structure.

2. The ventilation bridge system for long tunnels as described in claim 1, characterized in that, A duct (7) is installed in the upper section. The duct (7) runs along the direction of the transverse tunnel. Both ends of the duct pass through the blocking plate (6) at their respective ends. One end of the duct (7) is located at the entrance of the first transverse tunnel (1-3) and is connected to the first fan (1-5) located outside the first transverse tunnel (1-3). The other end extends to the working face inside the main tunnel (1-2) and is used to deliver fresh air to the working face of the main tunnel (1-2).

3. The ventilation bridge system for long tunnels as described in claim 2, characterized in that, The outer side of the wind bridge partition (3) is an arc shape extending outward from top to bottom.

4. The ventilation bridge system for long tunnels as described in claim 3, characterized in that, A horizontal wall (5) made of concrete is covered on the bridge deck (4), and the sidewall of the horizontal wall (5) is closely fitted to the inner wall of the tunnel.

5. A ventilation bridge system for long tunnels as described in claim 4, characterized in that, A second fan (1-8) is provided inside the guide (1-1), in front of the wind bridge body (1), and behind the second transverse tunnel (1-4). The second fan (1-8) is used to supply air to the working face in front of the guide (1-1) and the working face in front of the main tunnel (1-2).

6. A ventilation bridge system for long tunnels as described in claim 5, characterized in that, A horizontal beam connects two adjacent columns, and a horizontal secondary beam connects two diagonally opposite columns.

7. A ventilation bridge system for long tunnels as described in claim 6, characterized in that, A third fan (1-6) is provided at the inlet end of the guide (1-1) to supply air into the guide (1-1) and to transport it through the upper section to the guide (1-1) in front of the wind bridge body (1).

8. A ventilation bridge system for long tunnels as described in claim 7, characterized in that, A fourth fan (1-7) is installed at the entrance of the main tunnel (1-2), and the fourth fan (1-7) is used to supply air to the first working face of the forward excavation inside the main tunnel (1-2).

9. A construction method for a long tunnel ventilation bridge system as described in any one of claims 1-8, characterized in that, Includes the following steps: Step 1: The pilot tunnel (1-1) and the main tunnel (1-2) are excavated in parallel. A third ventilation fan (1-6) is installed at the entrance of the pilot tunnel (1-1), and a fourth ventilation fan (1-7) is installed at the entrance of the main tunnel (1-2). Before the tunnel excavation reaches the intersection of the first cross tunnel (1-3) and the pilot tunnel (1-1), the installation position of the main frame (2) is determined according to the design. The intersection area is excavated, and the main frame (2) is installed at the designed position. Step 2: Lay bridge deck panels (4) on the main frame (2) and in the intersection area. Step 3: In the lower section, and at both ends of the (1-1) flat guide (1-1) of the bridge deck (4), the wind bridge partition wall (3) is constructed with ordinary bricks and M7.5 cement mortar, and the side wall of the wall is in close contact with the tunnel initial support surface. In the upper section, a horizontal wall (5) is built on the bridge deck (4); in the upper section, and at both ends of the first transverse opening (1-3), a blocking plate (6) is built, and a ventilation duct through hole is reserved on the blocking plate (6); Step 4: Install the air duct (7) along the direction of the first horizontal hole (1-3), and pass both ends through the corresponding air duct outlet holes; A first fan (1-5) is connected to the inlet end of the first transverse opening (1-3) of the air duct (7); a second fan (1-8) is provided inside the flat guide (1-1), on the air outlet side of the air bridge body (1), and behind the second transverse opening (1-4). Excavation proceeds in both directions from the first transverse tunnel (1-3) to the main tunnel (1-2), forming two working faces. The first fan (1-5) supplies air to the two working faces in the main tunnel (1-2). Excavation proceeds in both directions from the second transverse tunnel (1-4) to the main tunnel (1-2), forming two working faces. The second fan (1-8) supplies air to the working face in front of the guide (1-1) and the two working faces in the main tunnel (1-2).

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