Double-lane highway tunnel jet fan adjustable embedded support assembly and construction method thereof

Abstract

The application provides a double-lane highway tunnel jet fan adjustable embedded support assembly and a construction method thereof, and belongs to the technical field of tunnel construction. The embedded support comprises a hanging rib, a hanging plate, an adjusting plate, a base plate, a round rod and a nut. The hanging plate is provided with a round hole, and the side surface is fixedly connected with the hanging rib to form an upper part of the support. The adjusting plate is a concave plate, comprising a web plate, an upper wing plate and a lower wing plate, and the web plate is provided with a channel hole. The lower wing plates of multiple adjusting plates are fixed on the base plate to form a lower part of the support. The upper part of the support corresponding to the adjusting plate is hung on the upper layer of the circular main rib of the secondary lining through the hook at the top end of the hanging rib. The round rod passes through the round hole of the hanging plate and the channel hole of the adjusting plate to connect the upper part of the support and the lower part of the support into an integral whole, and the round rod is supported by the lower layer of the circular main rib of the secondary lining. Two nuts are sleeved on the round rod. The application can improve the problems of great difficulty in support processing, great workload in embedded positioning and inaccurate positioning in the construction method of the existing tunnel jet fan embedded support.

Description

Technical Field

[0001] This invention belongs to the technical field of tunnel construction, and specifically discloses an adjustable pre-embedded support assembly for a jet fan in a two-lane highway tunnel and its construction method. Background Technology

[0002] Tunnel ventilation is an important safety guarantee during operation. Most long highway tunnels are designed with jet fans for enhanced ventilation. In the "Detailed Design Specifications for Ventilation of Highway Tunnels" (JTG / T D70 / 2-02-2014), Article 11.2.2 states that, under normal circumstances, two jet fans are arranged on the same cross section of a two-lane tunnel. At the same time, Article 11.2.4 stipulates that the structural bearing capacity supporting the fan should not be less than 15 times the actual static load of the fan, and a load test of the supporting structure should be carried out before the fan is installed. As embedded components in the tunnel jet fan support structure, the pre-embedded supports are generally designed as fixed supports. Before the secondary lining trolley is positioned, the supports are roughly adjusted and positioned by welding with the secondary lining reinforcement. After the trolley is positioned, the operating space behind the panel is extremely small. The fine adjustment of the supports often requires repeated moving and positioning of the secondary lining trolley. This frequently results in the support steel plate not fitting tightly against the trolley panel, and after demolding, the surface of the support steel plate is covered with concrete. Even during the secondary lining concrete pouring process, the supports may shift, requiring rework. This not only damages the secondary lining concrete and waterproofing layer structure but can also affect the secondary lining construction progress. Furthermore, the fabrication of components such as hook steel plates and hook bolts increases the construction difficulty. Therefore, there is an urgent need to develop a pre-embedded support that is easy to process, reliably stressed, and facilitates precise positioning. Summary of the Invention

[0003] The purpose of this invention is to provide an adjustable pre-embedded support assembly for a jet fan in a two-lane highway tunnel and its construction method, so as to improve the problems of high difficulty in support processing, large workload in pre-embedded positioning, and inaccurate positioning in the existing construction methods for pre-embedded supports of tunnel jet fans.

[0004] To achieve the above objectives, the present invention provides an adjustable pre-embedded support assembly for a jet fan in a two-lane highway tunnel, comprising two sets of pre-embedded supports symmetrically arranged on the secondary lining of the tunnel with the tunnel centerline as the axis of symmetry; each set of pre-embedded supports includes two pre-embedded supports I and two pre-embedded supports II, the two pre-embedded supports I being used to fix both sides of the jet fan, and the two pre-embedded supports II being used to fix both ends of the jet fan; each pre-embedded support I and each pre-embedded support II includes a hanging rod, a hanging plate, an adjusting plate, a base plate, a round rod, and a nut; the hanging plate is provided with a round hole, and its side is fixedly connected to the hanging rod to form the upper part of the support; the adjusting plate is a concave plate, including The web consists of an upper flange and a lower flange on each side of the web, with grooves and holes on the web. The lower flanges of multiple adjusting plates are fixed to the base plate according to the spacing of the secondary lining circumferential main reinforcements to form the lower part of the support. The upper part of the support, corresponding to the adjusting plates, is suspended from the upper circumferential main reinforcements of the secondary lining by hooks at the top of the hanging bars. A round rod passes through the round hole of the hanging plate and the groove hole of the adjusting plate to connect the upper and lower parts of the support into one unit. The round rod is supported by the lower circumferential main reinforcements of the secondary lining. The hanging bars and adjusting plates are located on both sides of the hanging plate. Two nuts are fitted on the round rod, located inside or outside the two outermost adjusting plates, with a gap between them and the outermost adjusting plate.

[0005] Furthermore, the outermost two hanging plates are fixed with baffles on the sides that contact the upper wing plate; the upper wing plates of the outermost two adjusting plates are connected to the baffles by a reaction spring.

[0006] Furthermore, triangular ribs are fixed between the support plate and the hanging plate.

[0007] Furthermore, each support plate is fixed with multiple hanging rods; the upper and lower parts of the support are connected by multiple round rods.

[0008] Furthermore, each end of the round rod extends beyond the base plate area with a secondary circumferential main reinforcement bar.

[0009] Furthermore, both embedded support I and embedded support II are made of steel.

[0010] The present invention also provides a construction method for the above-mentioned adjustable pre-embedded support assembly for jet fans in two-lane highway tunnels, comprising the following steps:

[0011] S1, Install the secondary lining circumferential reinforcement;

[0012] S2, Measurement point

[0013] The four embedded supports I of the two jet fans are located at the same mileage. The two embedded supports II of the same jet fan are set at the front and rear ends of the vertical line connecting the center points of the base plates of the two embedded supports I. The center points of the base plates of the eight embedded supports are determined according to the installation mileage of the jet fan and the above data, and the marks are made on the circumferential main reinforcement of the lower layer of the secondary lining.

[0014] S3, Upper part of mounting bracket

[0015] Hang the upper part of the support on the circumferential main reinforcement of the secondary lining according to the center point of the measured base plate, and fix it by spot welding first.

[0016] S4, Lower part of mounting bracket

[0017] Mark the center point on the base plate. Use the threaded rods at both ends to pass through the round holes of the hanging plate and the groove holes of the adjusting plate to connect the upper and lower parts of the support. Install matching nuts at both ends of the round rods of each pre-embedded support for limiting. Leave a gap between the nuts and the adjusting plate to allow the lower part of the support to move up and down. After the upper and lower parts of the support are connected, the lower part of the support is at the maximum radial downward displacement.

[0018] S5, Measurement Verification

[0019] Verify that the position of each embedded support is accurate:

[0020] Push the lower part of the support upward to the design position, measure and verify the mileage and offset of the center point of the base plate, verify the accuracy of the longitudinal position of the embedded support by the mileage, and verify the accuracy of the lateral position of the embedded support by the offset. If the longitudinal and lateral positions exceed the deviation range, readjust the installation position of the hanging bars on the upper circumferential main reinforcement of the secondary lining. After verification, weld each hanging bar and round rod firmly to the upper and lower circumferential main reinforcement of the secondary lining.

[0021] S6, Second Lining Trolley Positioning

[0022] After the secondary lining trolley moves to the design position, the side mold is raised and expanded to the design size, the lower part of the support is pushed to the design position, the base plate is closely attached to the trolley panel, and before the end template is sealed, the close attachment between the base plate and the trolley panel is checked again.

[0023] S7, pouring secondary lining concrete

[0024] S8, demolding of the trolley.

[0025] In step S3, support plates are fixed on the sides of the two outermost hanging plates that contact the upper wing plate, and a reaction spring is fixed on the bottom surface of the support plate; in step S4, the upper wing plates of the two outermost adjusting plates are fixedly connected to the bottom end of the reaction spring.

[0026] In step S4, each end of the round rod extends beyond the base plate area by one secondary lining circumferential main reinforcement bar.

[0027] In step S7, when the secondary lining concrete is poured to the top of the arch, the backward pouring method is used. After the end formwork is sealed, the extrusion method is used to pour the concrete to ensure that the concrete at the top of the arch is poured densely.

[0028] The present invention has the following beneficial effects:

[0029] 1. All materials used in the fabrication of the embedded supports are conventional materials available on site, which are readily available and the fabrication process is simple;

[0030] 2. The embedded support is designed as an adjustable structure and is equipped with a reaction spring to ensure that the base plate and the secondary lining trolley panel are in close contact, thus achieving precise positioning of the embedded support.

[0031] 3. The upper and lower parts of the support, together with the double-layer main reinforcement and secondary lining concrete, form an integral encapsulated load-bearing structure, which is reliable in bearing load and meets the installation requirements of the jet fan.

[0032] 4. The pre-embedded installation and positioning of the supports require minimal work and can achieve precise positioning in one go;

[0033] In summary, the adjustable pre-embedded support assembly for jet fans in two-lane highway tunnels and its construction method provided by this invention enrich tunnel construction technology and have extremely wide application value. Attached Figure Description

[0034] Figure 1 A flowchart illustrating the construction method for adjustable pre-embedded support components for jet fans in a two-lane highway tunnel.

[0035] Figure 2 A schematic diagram showing the elevation position of the pre-embedded supports for two jet fans;

[0036] Figure 3 A schematic diagram showing the planar position of the pre-embedded supports for two jet fans;

[0037] Figure 4 This is the front view of the pre-embedded support I (after the trolley is positioned, in close contact state).

[0038] Figure 5 This is the main view of the pre-embedded support II facade structure (after the trolley is positioned, in close contact).

[0039] Figure 6 This is a side view of the pre-embedded support II (after the trolley is positioned, in a close-fitting state).

[0040] Figure 7 This is a top view of the pre-embedded support II (after the trolley is positioned, in a tightly fitted state).

[0041] Figure 8 This is the main view of the pre-embedded support II facade structure (at the point of maximum displacement at the bottom of the support before the trolley is positioned).

[0042] In the diagram: 1-Hanging bar, 2-Hanging plate, 3-Adjusting plate, 4-Base plate, 5-Round rod, 6-Nut, 7-Reaction spring, 8-Support plate, 9-Triangular rib, 101-Lower circumferential main reinforcement of secondary lining, 102-Upper circumferential main reinforcement of secondary lining, 103-Tunnel centerline, 104-Jet fan installation mileage station, 201-Embedded support I, 202-Embedded support II. Detailed Implementation

[0043] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] This embodiment takes a particularly long tunnel as an example to discuss in detail the adjustable pre-embedded support assembly for jet fans in two-lane highway tunnels and its construction method.

[0045] 1. Install secondary lining reinforcement

[0046] Install the secondary lining reinforcement according to the design spacing. The circumferential main reinforcement of the secondary lining uses C22 steel bars with a layer spacing of 20cm. The installation error is controlled within ±5mm. The lower layer reinforcement should have no less than 4 bars per meter. 2 Spacers should be installed, evenly distributed, and securely tied to ensure that the thickness of the protective layer for the lower steel reinforcement is not less than 4cm.

[0047] 2. Precast embedded supports

[0048] The embedded support I201 and the two embedded supports II202 each include a hanging bar 1, a hanging plate 2, an adjusting plate 3, a base plate 4, a round rod 5, and a nut 6.

[0049] The hanging reinforcement bar 1 is made of C16 steel bar, and the hanging plate 2 is made of 1cm thick steel plate. Three hanging reinforcement bars 1 are installed on each hanging plate 2. The secondary lining circumferential main reinforcement uses C22 steel bars with a layer spacing of 20cm and a protective layer of 4cm. The distance from the bottom of the hanging reinforcement bar 1 to the center of the upper secondary lining reinforcement is determined to be 13cm, that is, the distance from the bottom of the hanging reinforcement bar 1 to the inner contour surface of the secondary lining is 12cm. The hanging reinforcement bar 1 is welded to the surface of the 1cm thick hanging plate 2 on both sides. The hanging plate 2 is 22cm high and wide. The two hanging reinforcement bars 1 on both sides are 2cm from the edge of the hanging plate 2, and the middle hanging reinforcement bar 1 is centrally located, with its bottom 9cm from the bottom of the hanging plate 2. Two A22 round holes are symmetrically set at a height of 4.2cm from the bottom of the hanging plate 2, with a horizontal center-to-center spacing of 8.2cm between the holes.

[0050] The base plate 4 is made of 2cm thick steel plate. The base plate 4 of the pre-embedded support I201 is 140cm long and 30cm wide, and the base plate 4 of the pre-embedded support II202 is 40cm long and 30cm wide. The adjusting plate 3 is made of 14b channel steel. The adjusting plate 3 is set on the upper surface of the base plate 4 at a spacing of 25cm between the secondary circumferential main reinforcement bars. The lower surface is treated with anti-rust treatment. Each adjusting plate 3 is 25cm wide and is fully welded to the base plate 4 in the transverse center. The longitudinal ends of the base plate 4 are 4.5cm away from the nearest weld point of the adjusting plate 3. On the web of the adjusting plate 3, there are two vertical slot holes at a height of 3cm from the lower flange. The slot holes are 2.6cm wide and 8cm high. The vertical ends of each slot hole are two semicircles with a diameter of 2.6cm. The horizontal center distance between the two slot holes is 8.2cm.

[0051] Round bar 5 is an A20 continuous round steel bar with threads at both ends.

[0052] A reaction spring 7 is installed on the back of the hanging plate 2 at both ends of each pre-embedded support. The bottom of the reaction spring 7 is welded to the adjusting plate 3, and the top is welded to a 1cm thick steel support plate 8. The support plate 8 is 4cm long and 3.5cm wide. The support plate 8 is welded at a height of 2.3cm from the top of the hanging plate 2, and a 1cm thick steel triangular rib 9 is installed in the center and welded to the hanging plate 2 and the support plate 8 for reinforcement. The vertical right angle side of the triangular rib 9 is 1.5cm long and the horizontal right angle side is 2.5cm long.

[0053] All steel materials used for the embedded supports are Q235-A. Before welding, rust and burrs should be removed, the weld should be continuous, and there should be no welding defects such as slag inclusions, porosity, or cracks.

[0054] 3. Measurement points

[0055] The embedded supports for the two jet fans are symmetrically arranged along the tunnel centerline 103, with the long side of the base plate 4 of each embedded support parallel to the longitudinal direction of the tunnel. The longitudinal centerlines of the base plates 4 of the two embedded supports I201 of the same jet fan are horizontally distanced from the tunnel centerline 103 by 85cm and 195cm respectively, while the longitudinal centerlines of the base plates 4 of the two embedded supports II202 are horizontally distanced from the tunnel centerline 103 by 140cm. The four embedded supports I201 of the two jet fans are located at the same mileage. The two embedded supports II202 of the same jet fan are located at the front and rear ends of the perpendicular line connecting the center points of the base plates of the two embedded supports I201. The distance from the center point of the base plate of embedded support II to the center point of the base plate of embedded support I is 175cm. The center points of the base plates of the eight embedded supports are determined based on the installation mileage of the jet fans and the above data, and marked on the circumferential main reinforcement 101 of the lower layer of the secondary lining.

[0056] 4. Install the upper part of the support

[0057] The upper part of the support is a combined welded component consisting of hanging ribs 1, hanging plates 2, support plates 8, triangular ribs 9, and reaction springs 7. Pre-embedded support I 201 has six hanging structures, with reaction springs 7 installed only at the two end hanging structures. Pre-embedded support II 202 has two hanging structures, both equipped with reaction springs 7. The upper welded components of the support are distributed and suspended on the upper circumferential main reinforcement 102 of the secondary lining according to the measured center point of the base plate 4, and then spot-welded for fixation.

[0058] 5. Install the lower part of the support

[0059] The lower part of the support is a welded assembly of an adjusting plate 3 and a base plate 4. The center point is marked on the base plate 4 using a diagonal method. A long A20 round steel bar with threaded ends is passed through the A22 round hole and the groove hole on the adjusting plate 3 to connect the upper and lower welded components of the support. The round rod 5 extends longitudinally at both ends beyond the base plate 4, covering one secondary lining circumferential main reinforcement 101 at each end, and extends 5cm beyond each of these reinforcements to increase the load-bearing support points. M20 nuts are installed at both ends of the round rod 5 of each pre-embedded support for positioning. A gap is left between the nut 6 and the adjusting plate 3 to allow for the vertical movement of the lower part of the support. After the upper and lower parts of the support are connected, the lower part of the support is at its maximum radial downward displacement under the action of gravity and the reaction spring 7.

[0060] 6. Measurement verification

[0061] Verify the accuracy of the position of each embedded support. Push the lower part of the support upwards to the designed position, and measure and verify the mileage and offset of the center point of the base plate 4. Verify the accuracy of the longitudinal position of the embedded support by measuring the mileage, and verify the accuracy of the lateral position of the embedded support by measuring the offset. The longitudinal and lateral position deviations should be controlled within ±5mm. If the deviation exceeds the range, readjust the installation position of the hanging bar 1 on the upper circumferential main reinforcement 102 of the secondary lining. After verification, weld each hanging bar 1 and A20 connecting round steel to the upper and lower circumferential main reinforcements of the secondary lining securely.

[0062] 7. Positioning of the secondary lining trolley

[0063] After the secondary lining trolley moves to the designed position, the side mold is raised and expanded to the designed dimensions. The lower part of the support is pushed to the designed position and, under the action of gravity and the reaction springs 7 at both ends, it is tightly attached to the trolley panel. Before sealing the end template, the tightness between the bottom base plate 4 and the trolley panel is checked again.

[0064] 8. Pouring secondary lining concrete

[0065] When the secondary lining concrete is poured to the top of the arch, the backward pouring method is used. After the end formwork is sealed, the extrusion method is used to pour the concrete at the top of the arch to ensure that the concrete is poured densely.

[0066] 9. Demolding the trolley

[0067] When the secondary lining concrete reaches 75% of its design strength, the secondary lining trolley is demolded, and the position of base plate 4 is re-measured and checked.

[0068] Compared with traditional construction methods, this method offers advantages such as convenient material sourcing for bearing processing, simple processing technology, and minimal workload for bearing pre-embedding, installation, and positioning. It ensures close contact between the base plate 4 and the secondary lining trolley panel, enabling precise one-time positioning of the bearing. The upper and lower parts of the bearing, together with the double-layer main reinforcement and secondary lining concrete, form an integral encapsulated load-bearing structure, ensuring reliable load-bearing capacity and meeting the installation requirements of jet fans. This method enriches tunnel construction technology and has extremely broad application value.

[0069] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An adjustable pre-embedded support assembly for a jet fan in a two-lane highway tunnel, characterized in that, This includes two sets of pre-embedded supports symmetrically arranged on the secondary lining of the tunnel with the tunnel centerline as the axis of symmetry. Each set of embedded supports includes two embedded supports I and two embedded supports II. The two embedded supports I are used to fix the two sides of the jet fan, and the two embedded supports II are used to fix the two ends of the jet fan. Both embedded supports I and two embedded supports II include hanging rods, hanging plates, adjusting plates, base plates, round rods and nuts. The hanging plate is provided with round holes, and the side is fixedly connected to the hanging rod to form the upper part of the support. The adjusting plate is a concave plate, including a web and upper and lower wing plates located on both sides of the web. The web is provided with vertical groove holes, and each groove hole has two semicircles at its two ends. The lower flanges of multiple adjustment plates are fixed to the base plate according to the spacing of the secondary lining circumferential main reinforcement to form the lower part of the support; The upper part of the support corresponding to the adjustment plate is suspended from the upper circumferential main reinforcement of the secondary lining by the hook at the top of the suspension bar; The round rod passes through the round hole of the hanging plate and the groove hole of the adjusting plate to connect the upper part of the support and the lower part of the support into one piece. The two ends of the round rod are threaded. The round rod is supported by the main reinforcement from the lower layer of the secondary lining. The hanging reinforcement and the adjusting plate are located on both sides of the hanging plate. Two nuts are fitted onto the round rod, located inside or outside the two outermost adjusting plates, with a gap between them and the outermost adjusting plate; The outermost two hanging plates are fixed with support plates on the sides that contact the upper wing plate; The upper flanges of the two outermost adjusting plates are connected to the support plate by a reaction spring.

2. The adjustable pre-embedded support assembly for a jet fan in a two-lane highway tunnel according to claim 1, characterized in that, Triangular ribs are fixed between the support plate and the hanging plate.

3. The adjustable pre-embedded support assembly for a jet fan in a two-lane highway tunnel according to claim 2, characterized in that, Each hanging panel is fixed with multiple hanging ribs; The upper and lower parts of the support are connected by multiple round rods.

4. The adjustable pre-embedded support assembly for a jet fan in a two-lane highway tunnel according to claim 3, characterized in that, Each end of the round rod extends beyond the base plate area, with one secondary circumferential main reinforcement bar at each end.

5. The adjustable pre-embedded support assembly for a jet fan in a two-lane highway tunnel according to claim 4, characterized in that, Both embedded support I and embedded support II are made of steel.

6. A construction method for an adjustable pre-embedded support assembly for a jet fan in a two-lane highway tunnel as described in any one of claims 1-5, characterized in that, Includes the following steps: S1, Install the secondary lining circumferential reinforcement; S2, Measurement point The four embedded supports I of the two jet fans are located at the same mileage. The two embedded supports II of the same jet fan are set at the front and rear ends of the vertical line connecting the center points of the base plates of the two embedded supports I. The center points of the base plates of the eight embedded supports are determined according to the installation mileage of the jet fan and the above data, and the marks are made on the circumferential main reinforcement of the lower layer of the secondary lining. S3, Upper part of mounting bracket Hang the upper part of the support on the circumferential main reinforcement of the secondary lining according to the center point of the measured base plate, and fix it by spot welding first. S4, Lower part of mounting bracket Mark the center point on the base plate. Use the threaded rods at both ends to pass through the round holes of the hanging plate and the groove holes of the adjusting plate to connect the upper and lower parts of the support. Install matching nuts at both ends of the round rods of each pre-embedded support for limiting. Leave a gap between the nuts and the adjusting plate to allow the lower part of the support to move up and down. After the upper and lower parts of the support are connected, the lower part of the support is at the maximum radial downward displacement. S5, Measurement Verification Verify that the position of each embedded support is accurate: Push the lower part of the support upward to the design position, measure and verify the mileage and offset of the center point of the base plate, verify the accuracy of the longitudinal position of the embedded support by the mileage, and verify the accuracy of the lateral position of the embedded support by the offset. If the longitudinal and lateral positions exceed the deviation range, readjust the installation position of the hanging bars on the upper circumferential main reinforcement of the secondary lining. After verification, weld each hanging bar and round rod firmly to the upper and lower circumferential main reinforcement of the secondary lining. S6, Second Lining Trolley Positioning After the secondary lining trolley moves to the design position, the side mold is raised and expanded to the design size, the lower part of the support is pushed to the design position, the base plate is closely attached to the trolley panel, and before the end template is sealed, the close attachment between the base plate and the trolley panel is checked again. S7, pouring secondary lining concrete S8, demolding of the trolley.

7. The construction method according to claim 6, characterized in that, In step S3, support plates are fixed on the sides where the two outermost hanging plates contact the upper wing plate, and reaction springs are fixed on the bottom surface of the support plates. In step S4, the upper wing plates of the two outermost adjusting plates are fixedly connected to the bottom end of the reaction spring.

8. The construction method according to claim 7, characterized in that, In step S4, each end of the round rod extends beyond the base plate area by one secondary lining circumferential main reinforcement bar.

9. The construction method according to claim 8, characterized in that, In step S7, when the secondary lining concrete is poured to the top of the arch, the backward pouring method is used. After the end formwork is sealed, the extrusion method is used to pour the concrete to ensure that the concrete at the top of the arch is poured densely.

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