A formwork support structure and construction method for a side box culvert

Abstract

The present application relates to the technical field of shield tunnel construction, and particularly relates to a side box culvert formwork support structure and a construction method, comprising a plurality of inclined support groups, an arc-shaped bottom plate formwork is arranged on each inclined support group in an inclined manner, an anchoring area a is arranged on the outer circumferential surface of the arc-shaped bottom plate formwork, a top plate formwork is horizontally arranged at the upper end of the arc-shaped bottom plate formwork, an anchoring area b is arranged on the upper side of the top plate formwork, and a support unit is arranged on the lower side of the top plate formwork. The arc-shaped steel formwork + fastener type steel pipe support structure is used to construct the side box culvert, and the difference from the lining formwork construction is that the area used for the lining trolley to walk on the bottom of the arc-shaped bottom plate does not need to be poured in advance, the construction process can be simplified, time can be saved, and the construction is more flexible in stages, which is helpful to adapt to different geological environments and construction requirements, and solves the uneven construction problem in the case that the progress is faster or the formwork trolley construction progress is lagged.

Description

Technical Field

[0001] This invention relates to the field of shield tunnel construction technology, and in particular to a formwork support structure and construction method for a side box culvert. Background Technology

[0002] The statements herein provide only background information in relation to this invention and do not necessarily constitute prior art.

[0003] During tunnel boring machine (TBM) construction, to support traffic facilities and accommodate various other infrastructure, the bottom of the internal structure is designed as a box culvert. During construction, segment transport vehicles and material transport vehicles utilize the assembled box culvert surface for synchronous transport, and other internal structures can be constructed simultaneously without interference, thus saving time and creating convenient construction conditions.

[0004] Currently, box culverts generally include intermediate precast box culverts and side box culverts. Side box culverts are further divided into cast-in-place structures and precast structures. Regardless of the type, the intermediate precast box culverts are installed first, followed by the construction of the side box culverts. However, in the current construction method of lining formwork for cast-in-place side box culverts, uneven construction can occur when the progress is fast or the formwork trolley construction is lagging behind, failing to meet the requirements for rapid progress and schedule coordination. Summary of the Invention

[0005] The purpose of this invention is to address the aforementioned shortcomings by providing a formwork support structure and construction method for a side box culvert.

[0006] To solve the above technical problems, the present invention adopts the following technical solution: a template support structure for a side box culvert, which is set inside the shield tunnel segment and connected to the end of the intermediate precast box culvert. The two ends of the intermediate precast box culvert are provided with supporting brackets, including multiple diagonal bracing groups that are set at the supporting brackets and are equidistantly distributed along the extension direction of the shield tunnel segment. The ends of the corresponding shield tunnel segments on the multiple diagonal bracing groups are provided with arc-shaped bottom plate templates. The outer circumference of the arc-shaped bottom plate template is provided with rebar anchoring areas a distributed on the inner wall of the shield tunnel segment. The upper end of the arc-shaped bottom plate template is horizontally provided with a top plate template connecting the supporting brackets and the shield tunnel segment. The upper side of the top plate template is provided with rebar anchoring areas b. The rebar anchoring areas a and b are used to pour concrete and solidify to form the side box culvert. The lower side of the top plate template is provided with a support unit for supporting the reinforced concrete load.

[0007] Furthermore, the support unit is composed of multiple upright pole groups that are equidistantly distributed along the extension direction of the shield tunnel segment. Each upright pole group includes multiple upright poles, and the multiple upright poles are equidistantly distributed laterally within the area enclosed by the end of the intermediate precast box culvert, the arc-shaped bottom plate template, and the top plate template.

[0008] Furthermore, a top support is provided at the top of the upright; The top support is used to adjust the height of the upright and to support the end face of the top plate template.

[0009] Furthermore, a horizontal bar is provided between the end of the intermediate precast box culvert and the arc-shaped bottom plate template, and a swivel fastener is provided at the position where the horizontal bar intersects with the vertical bar. Connecting rods distributed along the extension direction of the shield tunnel segment are provided between adjacent swivel fasteners located on two facades.

[0010] Furthermore, each of the aforementioned diagonal bracing groups includes multiple diagonal braces, all of which employ an adjustable screw structure. The ends of the multiple diagonal braces corresponding to the arc-shaped base plate template are equidistantly distributed along the arc length direction of the arc-shaped base plate template, and the other ends of the multiple diagonal braces are fixed to the supporting bracket.

[0011] Furthermore, the lower surface of the top slab template is evenly distributed with supporting ribs, which include main ribs and secondary ribs. The main ribs are perpendicular to the intermediate precast box culvert and are arranged at equal intervals, while the secondary ribs are parallel to the intermediate precast box culvert and are arranged at equal intervals.

[0012] Furthermore, the arc-shaped base plate template is provided with an inspection port; The inspection port serves as both a window for concrete pouring and vibration, and is used for inspecting the quality of concrete pouring.

[0013] A construction method for a formwork support structure of a side box culvert, the specific method including the following steps: S1, Construction Preparation: In preparation for pouring concrete for the side box culvert, the reinforcement of each part of the steel bar was verified to be accurate according to the construction drawings, and the shape and dimensions of each part of the steel bar were determined so that the side box culvert and the shield tunnel segment could be connected by steel bar installation. S2, Reinforcement binding of the curved bottom slab: The longitudinal reinforcement of the bottom slab is arranged with C14@800 throughout, and the reinforcement of the bottom slab arc is arranged with C14@150. The reinforcement anchored into the shield tunnel segment is tied and fixed with the longitudinal reinforcement with tie wire. S3, Installation of curved base plate template: Use a diagonal bracing group to support the arc-shaped bottom plate template installed on the centripetal side of the rebar area a on the shield tunnel segment, and fix the other end of the diagonal bracing group to the support bracket through the diagonal bracing ears; S4, Curved base plate casting: The concrete is poured into the curved base plate template from both sides via a movable chute, and the pouring is carried out in symmetrical layers on both sides. S5, Support System Setup: On the arc-shaped base plate formwork, a fastener-type steel pipe is used as the formwork support system. The support system uses steel pipes as vertical poles, horizontal poles, and ground poles for connection. S6, Top slab formwork installation: In the support system, the top of the support unit is supported by a top support and the top plate template is horizontally connected to the end face of the middle precast box culvert, and support ribs are evenly arranged below the top plate template. S7, Top slab reinforcement binding: The same steel bar binding method is used, in which the tie bars are arranged in a staggered pattern, and the steel bars of the top slab of the side box culvert are connected to the reserved steel bar connectors of the middle precast box culvert. S8, Top slab pouring: Pour concrete from both sides of the top slab in the direction from the larger mileage to the smaller mileage, allowing the concrete to flow naturally to form a certain slope, with an interval of no more than 1.5 hours. S9, Concrete Curing: After the concrete is poured, cover the surface with geotextile and sprinkle water to keep it moist. S10, Formwork Removal: Before demolding, a concrete strength test must be conducted, and the formwork can only be removed after the strength meets the requirements, as witnessed by the supervising unit on site. The demolition sequence is the reverse of the erection sequence, that is, from top to bottom, from outside to inside, and layer by layer.

[0014] The beneficial effects of this invention are reflected in: This invention employs an arc-shaped steel formwork combined with a fastener-type steel pipe support for constructing side box culverts. Compared to traditional lining formwork construction, this method eliminates the need to first pour the bottom area of ​​the arc-shaped base slab for the lining trolley to move through, simplifying the construction process and saving time. Furthermore, the phased construction—first pouring the arc-shaped base slab, then the top slab—provides greater flexibility and helps adapt to different geological environments and construction requirements. It also solves the problem of uneven construction that occurs when the progress is fast or the formwork trolley construction is lagging behind. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the side box culvert template support from one perspective of the technical solution of the present invention; Figure 2 This is a schematic diagram of the side box culvert template support with support units assembled in one view of the technical solution of the present invention. Figure 3 This is a schematic diagram of the support unit of the technical solution of the present invention from one perspective; Figure 4 This is a diagram showing the distribution of rebar at the arc-shaped base plate location in the technical solution of this invention; Figure 5 This is a diagram showing the distribution of rebar installation at the top slab location in the technical solution of this invention; Figure 6 This is a cross-sectional view of the rebar distribution at the arc-shaped bottom plate and top plate positions in the technical solution of this invention; Figure 7 This is a schematic diagram of a typical section-side box culvert structure constructed using the technical solution of this invention; Figure 8 A schematic diagram of a side box culvert structure with an equipment platform constructed using the technical solution of this invention; Figure 9 This is a field construction drawing of the side box culvert formwork support according to the technical solution of the present invention.

[0016] In the picture: 1. Diagonal bracing assembly; 2. Curved base plate formwork; 3. Top plate formwork; 4. Vertical poles; 5. Top support; 6. Horizontal bar; 7. Connecting rod; 8. Support rib. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other. 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.

[0018] Please see Figure 1-9 This invention discloses a template support structure for a side box culvert, which is set inside a shield tunnel segment and connected to the end of an intermediate precast box culvert. Support brackets are provided at both ends of the intermediate precast box culvert. The structure includes multiple diagonal bracing groups 1, equidistantly distributed along the extension direction of the shield tunnel segment and positioned at the support brackets. Arc-shaped bottom plate templates 2 are provided at the ends of corresponding shield tunnel segments on the multiple diagonal bracing groups 1. Rebar anchoring areas a are provided on the outer periphery of the arc-shaped bottom plate template 2, distributed on the inner wall of the shield tunnel segment. A top plate template 3, horizontally connected between the support brackets and the shield tunnel segment, is provided at the upper end of the arc-shaped bottom plate template 2. Rebar anchoring areas b are arranged on the upper side of the top plate template 3. Rebar anchoring areas a and b are used for pouring concrete and solidifying to form the side box culvert. A support unit for supporting reinforced concrete loads is provided on the lower side of the top plate template 3.

[0019] In practice, the intermediate precast box culverts installed inside the shield tunnel segments along the tunnel's extension direction, and the integrated support brackets on both sides of the intermediate precast box culverts, are used in stages. The curved bottom plate template 2 is supported and fixed inside the shield tunnel segments using the diagonal bracing group 1, and the top plate template 3 is supported by the support unit and horizontally connected to the intermediate precast box culvert. In the later pouring process, the construction is carried out in stages, first pouring the curved bottom plate and then pouring the top plate. This makes the construction more flexible, helps to adapt to different geological environments and construction requirements, effectively solves the problem of uneven construction when the progress is fast or the progress of the template trolley is slow, simplifies the construction process, saves time, and improves construction efficiency.

[0020] The following is a supplementary explanation of the construction process when using a steel formwork support system: tying of the curved bottom slab reinforcement — installation of curved bottom slab formwork 2 — pouring of the curved bottom slab — erection of the support system — installation of the top slab formwork 3 — tying of the top slab reinforcement — pouring of the top slab.

[0021] In one embodiment, the support unit consists of multiple upright groups equidistantly distributed along the extension direction of the tunnel segment. Each upright group includes multiple uprights 4, which are equidistantly distributed laterally within the area enclosed by the end of the intermediate precast box culvert, the arc-shaped bottom slab template 2, and the top slab template 3. This design, with the support unit installed on the lower side of the top slab template 3, wherein the multiple uprights 4 included in the support unit are distributed at a spacing of 1000mm (longitudinal) × 600mm (lateral) within the area enclosed by the end of the intermediate precast box culvert, the arc-shaped bottom slab template 2, and the top slab template 3, can evenly distribute and bear the load of the concrete poured on the top slab template 3, thus improving the support strength of the support unit.

[0022] It should be noted that all uprights 4 are made of φ48×2.8mm steel pipes, and the heights of the three rows of uprights 4 are 1.4m, 1m, and 0.62m respectively.

[0023] In one embodiment, a top support 5 is provided at the top of the upright 4; The top support 5 is used to adjust the height of the upright 4 and is connected to the end face support of the top plate template 3. This design allows the top of the upright 4 to be adjusted relative to the bottom surface of the top plate template 3 by installing the top support 5 on top of the upright 4, and to be connected to the end face support of the lower top plate template 3, thus providing stable support for the top plate template 3 to withstand the load of the reinforced concrete.

[0024] It should be noted that the top support 5 adopts an adjustable U-shaped support structure, the outer diameter of the lead screw of the top support 5 is not less than 36mm, and the length inserted into the upright 4 is not less than 150mm.

[0025] In one embodiment, a horizontal bar 6 is provided between the end of the intermediate precast box culvert and the arc-shaped bottom plate template 2. A swivel coupler is provided at the intersection of the horizontal bar 6 and the vertical pole 4. Connecting rods 7, distributed along the extension direction of the tunnel segment, are provided between adjacent swivel couplers located on two facades. This design, through the horizontal bar 6 installed laterally between the end of the intermediate precast box culvert and the arc-shaped bottom plate template 2, and the swivel couplers installed at the intersection of the horizontal bar 6 and the vertical pole 4, and the connecting rods 7 fixed between the swivel couplers distributed on adjacent facades, allows for the construction of a three-dimensional support system within the area enclosed by the end of the intermediate precast box culvert, the arc-shaped bottom plate template 2, and the top plate template 3, ensuring support strength and construction stability.

[0026] In one embodiment, each of the diagonal bracing groups 1 includes multiple diagonal braces, all of which employ adjustable screw rod structures. The ends of the multiple diagonal braces corresponding to the arc-shaped base plate template 2 are equidistantly distributed along the arc length direction of the arc-shaped base plate template 2. The other ends of the multiple diagonal braces are fixed to the supporting brackets. This design, by equidistantly distributing the multiple diagonal bracing groups 1 along the conveying direction of the tunnel lining segments, can stably support and fix the arc-shaped base plate template 2 on the supporting brackets of the intermediate precast box culvert. Furthermore, the use of adjustable screw rod structures allows for adjustment based on the relative distance between the supporting brackets and the arc-shaped base plate, thus adapting to the thickness of the base plate of the side box culvert.

[0027] In one embodiment, the lower surface of the top slab formwork 3 is uniformly distributed with supporting ribs 8, each supporting rib 8 including main ribs and secondary ribs. The main ribs are perpendicular to the intermediate precast box culvert and are arranged at equal intervals, while the secondary ribs are parallel to the intermediate precast box culvert and are arranged at equal intervals. This design, with the main ribs arranged at 1000mm intervals and the secondary ribs arranged at 300mm intervals on the lower surface of the top slab formwork 3, can effectively distribute the pressure from the load above, including its own weight, construction load, equipment load, and temporary loads during use. This prevents excessive deformation during stress, ensuring that the top slab formwork 3 can withstand greater forces while avoiding uneven settlement or deformation.

[0028] In one embodiment, the arc-shaped base plate template 2 is provided with an inspection port; The inspection port serves as both a window for concrete pouring and vibration, and for inspecting the quality of the concrete pouring. This design, through the inspection port on the curved base plate formwork 2, allows for concrete pouring and vibration, and enables the inspection of pouring quality, ensuring the concrete is compacted.

[0029] A construction method for a formwork support structure of a side box culvert, the specific method including the following steps: S1, Construction Preparation: In preparation for pouring concrete for the side box culvert, the reinforcement of each part of the steel bar was verified to be accurate according to the construction drawings. The shape of the steel bar and the dimensions of each detail were determined, as well as the construction procedures for various structures, so as to connect the side box culvert and the shield tunnel segments by means of rebar installation.

[0030] The concrete strength grade is C40, and the concrete volume on one side is 2.31m³. 3 / m, the concrete volume on both sides of the first ring is 9.25m. 3 The concrete usage for each cycle section is 92.5m³. 3 The cycle consists of ten rings. It should be noted that, according to design requirements, the side box culverts and segments are connected by rebar anchoring. The top slab connecting rebars are 12mm diameter threaded steel bars spaced 200mm apart, and the curved bottom slab connecting rebars are 16mm diameter threaded steel bars spaced 500mm apart. The anchoring depth is 250mm for all rebars. The diameter of the anchoring hole is 4mm larger than that of the connecting rebar (i.e., 16mm for C12 connecting rebars and 20mm for C16 connecting rebars). After drilling, the anchoring holes are cleaned and purged using a wire brush and air pump, and then modified epoxy anchoring adhesive is injected. The adhesive must meet the requirement of a compressive strength of 120N / m² after curing. 2 The bond strength after curing is 15.4 N / m. 2 The water absorption rate is ≤0.06% (24h), and the tensile strength of the embedded steel bar anchor must meet the requirements (the tensile force value is taken as the area of ​​a single steel bar multiplied by the steel bar stress 360MPa).

[0031] Inspection method: On-site inspection of tensile pull-out bearing capacity.

[0032] Inspection quantity: Rebars of the same specification and model shall be grouped into one inspection batch. The sampling quantity shall be calculated as 1% of the total number of rebars in each batch, and shall not be less than 3 rebars.

[0033] Inspection requirements: No damage to the rebar adhesive or loosening of the rebar should occur during the pull-out test.

[0034] S2, Reinforcement binding of the curved bottom slab: The longitudinal reinforcement of the bottom slab is arranged with C14@800 throughout, and the reinforcement of the bottom slab arc is arranged with C14@150. The reinforcement anchored into the shield tunnel segments is tied and fixed with the longitudinal reinforcement.

[0035] It should be noted that, due to different design structures, the side box culverts are divided into two structural forms: the general section and the equipment platform section (an equipment installation platform is reserved every 500m in the equipment pipe gallery, with the platform size being 658mm wide × 10m long). That is, there are also two forms of bottom slab reinforcement binding.

[0036] S3, Installation of curved base plate template 2: The thickness of the curved base plate formwork 2 is 250mm. In the formwork system, the panel is a 5mm thick steel plate, the frame is 8mm×50mm, and the stiffening plate is 8×50mm (8# channel steel). The rear uses φ57×6mm adjustable screw braces, with a longitudinal spacing of 870mm, a transverse spacing of 900mm in the middle and 600mm on both sides, and the brace ears are 70×70×10mm, spaced at 870mm intervals. The adjustable screw braces are connected to the brace ears and locked and fixed to the supporting brackets of the intermediate precast box culvert.

[0037] S4, Curved base plate casting: Concrete for the curved base slab is poured from both sides along the curved surface via a self-made movable chute, poured symmetrically in layers with a layer thickness ≤500mm and an interval of ≤2 hours between adjacent layers. An immersion vibrator (φ50) is used for compaction at intervals ≤400mm, with a vibration time of 15~20s / point, until the surface shows signs of slurry and no air bubbles are visible. Inspection ports are provided on the curved base slab formwork 2, serving as both a window for concrete pouring and vibration, and also for checking the quality of the concrete pouring to ensure its compaction.

[0038] It should be noted that the curved bottom slab formwork 2 is poured first, and the formwork is removed when the strength reaches 2.5 MPa. Then the top slab formwork 3 is installed, the reinforcing steel is tied, and then the top slab formwork 3 is poured.

[0039] S5, Support System Setup: The arched bottom slab template 2 of the tunnel uses a fastener-type steel pipe as the template support system. The support system uses steel pipes as uprights 4, horizontal bars 6, and ground bars for connection, with a height of no more than 550mm from the ground.

[0040] It should be noted that the top support 5 at the top of the upright 4 is an adjustable U-shaped support. The outer diameter of the lead screw of the adjustable U-shaped support is not less than 36mm, and the length inserted into the upright 4 is not less than 150mm. The lead screw of the adjustable U-shaped support at one end of the horizontal bar 6 extends beyond the top horizontal bar 6 by no more than 650mm, and the exposed length of the thread is strictly prohibited from exceeding 400mm.

[0041] S6, Installation of top slab template 3: The thickness of the top slab formwork 3 is 400mm. In the formwork system, the top slab formwork 3 uses 15mm thick plywood, with each board measuring 2300mm in length and 1220mm in width. Below the top slab formwork 3, 80mm x 80mm square timber is used as main and secondary ribs. The main ribs are perpendicular to the intermediate precast box culvert at 1000mm intervals, and the secondary ribs are parallel to the intermediate precast box culvert at 300mm intervals. The support units are spaced 1000mm (longitudinal) x 600mm (transverse). All components are fabricated in the processing yard according to design requirements and then transported to the construction site for assembly. The secondary ribs of the formwork are arranged transversely, and the main ribs are arranged longitudinally. Short joints in the multi-layer plywood are all located on the secondary ribs.

[0042] S7, Top slab reinforcement binding: The method of tying the reinforcing bars of the top slab is the same as that of the bottom slab. The tie bars are arranged in a staggered pattern. The reinforcing bars of the top slab of the side box culvert are connected to the pre-reserved reinforcing bar connectors of the middle precast box culvert.

[0043] S8, Top slab pouring: The top slab of the side box culvert is poured from both sides, starting from the larger mileage and moving towards the smaller mileage, allowing the concrete to flow naturally and form a certain slope. During construction, it is important to ensure that the interval between the next layer of concrete on the slope does not exceed 1.5 hours, strictly controlling it within the initial setting time of the concrete. The concrete vibration should start from the bottom and gradually move upwards. After the concrete is poured and formed, before initial setting, it is rolled with an iron roller and a long scraper is used to control the elevation and flatness. Finally, a trowel is used to finish the surface to prevent shrinkage cracks.

[0044] S9, Concrete Curing: The side box culverts are covered with geotextile for moisture retention and curing. After the concrete is poured, the surface is covered with geotextile and water is sprinkled to prevent moisture loss from the concrete, thus promoting hydration and achieving a good moisture retention and curing effect. The geotextile should ensure 100% complete coverage of the concrete structure to prevent localized inadequate curing and the resulting drying shrinkage cracks.

[0045] S10, Formwork Removal: After the side box culvert structure slab is completed, when the concrete strength reaches 75% of the design strength, the construction unit shall conduct a concrete strength test before removing the formwork, and the supervision unit shall witness on-site that the strength meets the requirements before the formwork can be removed.

[0046] The dismantling sequence is the reverse of the erection sequence, that is, from top to bottom, from outside to inside, and layer by layer: S10.1 When dismantling the support unit, proceed from top to bottom, layer by layer. Do not start from one end; dismantle in parallel to prevent injury from falling debris. The specific dismantling sequence is as follows: 1) Remove horizontal bars: First remove the top horizontal bar, then remove the middle horizontal bar, and finally remove the sweeping bar.

[0047] 2) Removing the armpit support rod: Two people are needed to remove it. One person holds the support rod while the other person loosens the fastener and slowly removes it.

[0048] 3) Finally, dismantle the integral arc-shaped base and uprights and other basic components, and clean up the site.

[0049] S10.2 When removing the top slab formwork 3, loosen the top support one by one from one end of the square timber. After the top support under the entire square timber is loosened, remove the square timber and the top support below it. Then remove the other square timbers under the same plywood in the same way. After all the timbers under a plywood are removed, pry off the plywood. Remove the top slab formwork 3 one by one from one end of the construction section to the other in this way until it is completed.

[0050] S10.3, For the removal of the curved base plate formwork 2, first loosen the adjustable screw brace, then gently pry the steel formwork to detach it from the concrete, and then lift it away.

[0051] S10.4 All dismantled materials should be removed, transported, and cleaned up as they are dismantled, and nails should be removed immediately to prevent tripping or foot injuries.

[0052] It should be noted that each side box culvert section consists of 10 rings (20m). Before construction, the completed side box culverts are roughened, and the reserved reinforcing bars are welded. There is a construction joint between the curved side plate and the top plate, which is located 15cm below the haunch. Before pouring the top plate, the side plate needs to be roughened, and the reserved reinforcing bars of the side plate are welded to the top plate. Before constructing the curved bottom slab of the side box culvert, a section of the guardrail on both sides of the precast box culvert in the middle must be removed, and a precast steel ladder must be installed for construction personnel to access. The ladder is for personnel only; the transfer of materials such as reinforcing bars, formwork, and supports must be done using a side-mounted forklift, and manual carrying is strictly prohibited to prevent falls. Only one person can pass through the ladder at a time. When someone is passing through, someone must be present at the top or bottom to assist in securing the ladder. Single-person use of the ladder is prohibited. When no one is passing through, the ladder must be retracted and placed in a location that does not interfere with construction, and the area where the guardrail was removed must be temporarily fenced off with retractable guardrails.

[0053] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0054] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0055] Additionally, "multiple" refers to two or more.

[0056] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A construction method using a side box culvert formwork support structure, wherein the formwork support structure is installed inside the shield tunnel segment and connected to the end of the intermediate precast box culvert, and the two ends of the intermediate precast box culvert are provided with supporting brackets, characterized in that: The template support structure includes multiple diagonal bracing groups (1) arranged at the position of the supporting corbel and equidistantly distributed along the extension direction of the shield tunnel segment. The ends of the corresponding shield tunnel segments on the multiple diagonal bracing groups (1) are provided with arc-shaped bottom plate templates (2). The outer periphery of the arc-shaped bottom plate template (2) is provided with rebar anchoring areas a distributed on the inner wall of the shield tunnel segment. The upper end of the arc-shaped bottom plate template (2) is horizontally provided with a top plate template (3) connecting the supporting corbel and the shield tunnel segment. The upper side of the top plate template (3) is provided with rebar anchoring areas b. The rebar anchoring areas a and b are used to pour concrete and solidify to form a side box culvert. The lower side of the top plate template (3) is provided with a support unit for supporting the reinforced concrete load. The support unit is composed of multiple uprights that are equidistantly distributed along the extension direction of the shield tunnel segment. Each upright group includes multiple uprights (4). The multiple uprights (4) are equidistantly distributed laterally in the area enclosed by the end of the intermediate precast box culvert, the arc-shaped bottom plate template (2), and the top plate template (3). specific Includes the following steps: S1, Construction Preparation: In preparation for pouring concrete for the side box culvert, the reinforcement of each part of the steel bar was verified to be accurate according to the construction drawings, and the shape and dimensions of each part of the steel bar were determined so that the side box culvert and the shield tunnel segment could be connected by steel bar installation. S2, Reinforcement binding of the curved bottom slab: The longitudinal reinforcement of the bottom slab is arranged with C14@800 throughout, and the reinforcement of the bottom slab arc is arranged with C14@150. The reinforcement anchored into the shield tunnel segment is tied and fixed with the longitudinal reinforcement with tie wire. S3, Installation of curved base plate template (2): Use the diagonal bracing group (1) to support the arc-shaped bottom plate template (2) installed on the centripetal side of the rebar area a on the shield tunnel segment, and fix the other end of the diagonal bracing group (1) to the support bracket through the diagonal bracing ears; S4, Curved base plate casting: Concrete is poured into the arc surface from both sides of the arc-shaped bottom plate template (2) through a movable chute, and the pouring is carried out in symmetrical layers on both sides. S5, Support System Setup: On the arc-shaped base plate template (2), a fastener-type steel pipe is used as the template support system. The support system uses steel pipes as uprights (4), horizontal bars (6), and sweeping bars for connection. S6, Top slab formwork (3) installation: In the support system, a top support (5) is used to support the top plate template (3) at the top of the support unit and horizontally connects it to the end face of the middle precast box culvert, and support ribs (8) are evenly arranged below the top plate template (3). S7, Top slab reinforcement binding: The same steel bar binding method is used, in which the tie bars are arranged in a staggered pattern, and the steel bars of the top slab of the side box culvert are connected to the reserved steel bar connectors of the middle precast box culvert. S8, Top slab pouring: Pour concrete from both sides of the top slab in the direction from the larger mileage to the smaller mileage, allowing the concrete to flow naturally to form a certain slope, with an interval of no more than 1.5 hours. S9, Concrete Curing: After the concrete is poured, cover the surface with geotextile and sprinkle water to keep it moist. S10, Formwork Removal: Before demolding, a concrete strength test must be conducted, and the formwork can only be removed after the strength meets the requirements, as witnessed by the supervising unit on site. The demolition sequence is the reverse of the erection sequence, that is, from top to bottom, from outside to inside, and layer by layer.

2. The construction method using a side box culvert formwork support structure according to claim 1, characterized in that... The top of the upright (4) is provided with a top support (5); The top support (5) is used to adjust the height of the upright (4) and is supported and connected to the end face of the top plate template (3).

3. The construction method using a side box culvert formwork support structure according to claim 1, characterized in that: A horizontal bar (6) is provided between the end of the intermediate precast box culvert and the arc-shaped bottom plate template (2). A swivel fastener is provided at the position where the horizontal bar (6) intersects with the vertical bar (4). A connecting rod (7) is provided between the adjacent swivel fasteners located on the two facades, distributed along the extension direction of the shield tunnel segment.

4. The construction method using a side box culvert formwork support structure according to claim 1, characterized in that: Each of the diagonal bracing groups (1) includes multiple diagonal braces, all of which adopt an adjustable screw structure. One end of each of the multiple diagonal braces is connected to the arc-shaped base plate template (2) and is equidistantly distributed along the arc length direction of the arc-shaped base plate template (2). The other end of each of the multiple diagonal braces is fixed to the supporting bracket.

5. The construction method using a side box culvert formwork support structure according to claim 1, characterized in that: The lower surface of the top plate template (3) is evenly distributed with support ribs (8). The support ribs (8) include main ribs and secondary ribs. The main ribs are perpendicular to the intermediate precast box culvert and are arranged at equal intervals. The secondary ribs are parallel to the intermediate precast box culvert and are arranged at equal intervals.

6. The construction method using a side box culvert formwork support structure according to claim 1, characterized in that: The arc-shaped base plate template (2) is provided with an inspection port; The inspection port serves as both a window for concrete pouring and vibration, and is used for inspecting the quality of concrete pouring.

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