Construction method for concrete internal formwork support system of ultra-large wind tunnel diffuser section

Abstract

A construction method for a concrete internal formwork support system of an ultra-large wind tunnel diffuser section, comprising the steps of: S1. performing full simulation modeling on a flow channel structure and steel formworks by means of BIM technology and on the basis of a construction drawing; S2. after factory processing, using BIM data to recheck and assemble the steel formworks, and affixing QR codes; S3. performing on-site positioning and layout on each sectional segment of the internal steel formworks; S4, before the internal formwork support system is installed, BIM engineers using an internal steel cylinder formwork BIM model to create installation animation demonstrations, and conducting visualized disclosure for on-site management personnel and workers, and the workers installing the internal formwork support system on the basis of the order of the animation demonstrations; S5. when construction for a polygonal-to-square main diffuser section base slab surface and a structure support column concrete below same is complete and reaches strength, performing positioning and installation of steel formwork units and steel support truss units. The present invention can effectively ensure the effective integration of base slabs and steel formworks, prevent displacement of the steel formworks during installation, and reduce defects existing in construction, thereby improving the working efficiency.

Description

Construction method for concrete internal formwork support system of ultra-large wind tunnel diffusion section Technical Field

[0001] The invention relates to the field of concrete flow channel engineering technology, and in particular to a construction method for a concrete internal formwork support system for the diffusion section of an ultra-large wind tunnel. Background Technology

[0002] As the automotive industry continues to demand higher performance and efficiency, more and more large automakers and research institutes are planning to build their own large-scale concrete wind tunnel testing laboratories. The diffuser section within the wind tunnel is a crucial part of the design, serving to smoothly transition between the wind tunnel chamber and the test section, reducing energy loss and turbulence, and ensuring the uniformity and stability of the airflow within the test section.

[0003] The diffuser section of the wind tunnel is typically designed to gradually transition from a polygonal circular cross-section in the wind turbine chamber to a square cross-section in the test section. This design requires extremely high precision to ensure a smooth transition of airflow during diffusion, avoiding unnecessary turbulence and pressure loss. Since the diffuser section is usually over 30 meters long, as the inner wall of the wind tunnel, its spatial positioning and inner surface flatness deviation must not exceed 5mm to ensure the quality of the test section's flow channel, such as the uniformity of airflow velocity distribution, the magnitude of the average airflow direction deviation from the wind tunnel axis, the pressure gradient along the wind tunnel axis, the uniformity of cross-sectional temperature distribution, airflow turbulence, and noise level. Furthermore, due to the extremely high airflow velocity inside the wind tunnel, reaching 250 km / h, post-construction repairs to the inner surface are strictly prohibited. It can be seen that constructing an automotive wind tunnel places very high demands on the construction precision of the wind tunnel's inner wall. Therefore, the construction of the internal formwork support system is the most critical step. Moreover, because the wind tunnel diffuser section is a gradually deforming structure with different dimensions for each cross-section, the traditional wooden formwork and steel pipe scaffolding support system is no longer sufficient to meet the on-site construction and quality precision requirements. Summary of the Invention

[0004] The invention aims to address the shortcomings of existing technologies by providing a construction method for an internal formwork support system for the diffusion section of an ultra-large wind tunnel. This method effectively solves the construction difficulties of transforming a polygonal circular diffusion section into a square one in an ultra-large wind tunnel. By applying this method, an internal formwork support system that meets the construction accuracy requirements can be built, ensuring the smooth completion of the construction.

[0005] To achieve the above objectives, the invention adopts the following technical solution:

[0006] The construction method for the concrete internal formwork support system of the diffusion section of an ultra-large wind tunnel includes the following steps:

[0007] S1. Using BIM technology, a full simulation model of the flow channel structure and steel formwork is created based on the construction drawings. Model data is extracted, and the size data of the steel formwork is determined piece by piece through precise virtual assembly. A family library of prefabricated steel formwork for the project is established. Node drawings are generated for the 3D model of each steel formwork and fastener, showing the elevation of the four corners of each steel formwork piece in detail. The family library of steel formwork information is fed back to the steel formwork processing manufacturer, who can directly extract the size information of the steel formwork model for steel formwork processing.

[0008] S2. After the factory finishes processing, the steel formwork is re-verified and assembled using BIM data, and QR codes are affixed. Once the inspection is passed, it is transported to the construction site. After the steel formwork arrives on site, the materials are inspected, and the dimensions, flatness, curvature, and chord length of each steel formwork are verified piece by piece according to the QR code data to ensure that the design requirements are met.

[0009] S3. Conduct on-site positioning and layout of each section of the internal steel formwork. When conducting on-site positioning and layout of each section of the internal steel formwork, calculate the distance from the center point of the flow channel to the intersection of each inclined plane based on the BIM model and CAD drawings of each flow channel section to locate the corresponding section.

[0010] S4. Before the installation of the internal formwork support system, the BIM engineer uses the BIM model of the internal steel cylinder formwork to create an installation animation demonstration and provides a visual briefing to the site management personnel and workers. The workers then install the internal formwork support system according to the sequence of the animation demonstration.

[0011] S5. After the concrete construction of the bottom plate of the polygonal-to-square main diffusion section and the structural support columns below it is completed and reaches the required strength, the steel formwork unit and the steel support truss unit are positioned and installed.

[0012] The positioning and installation method for the steel formwork unit and the steel support truss unit is as follows:

[0013] P1. Erect the external scaffolding unit, install the outer bottom plate steel formwork, the corresponding outer inclined steel formwork and the inclined external support, and pour the bottom plate concrete of the wind tunnel diffusion section.

[0014] P2. Install the steel formwork units corresponding to the inner inclined side formwork, and pour the bottom slab concrete horizontally;

[0015] P3. Install the longitudinal support columns and remaining transverse support columns of the steel formwork units and steel support truss units corresponding to the inner wall bottom formwork and side wall formwork as a whole. The longitudinal support columns and transverse support columns are vertically connected to the first horizontal support by bolts at the intersection.

[0016] P4. Install the remaining steel formwork units and the remaining steel support truss units of the inner steel cylinder formwork as a whole, and install the horizontal and longitudinal support columns. The support construction and formwork construction shall be carried out simultaneously until the second horizontal support is installed.

[0017] P5. Install the steel formwork units and steel support truss units corresponding to the top slab formwork;

[0018] P6. To ensure that the cross-sectional dimensions of the steel formwork meet the design requirements, the side wall and top plate steel formwork are installed ring by ring from the octagonal opening to the square opening for each layer.

[0019] P7. After the overall installation of the steel formwork unit and steel support truss unit of the inner steel cylinder formwork is completed, pour the lower inclined plate;

[0020] P8. Support the outer steel formwork of the side wall and pour concrete. After the concrete pouring is completed, tie up the outer steel formwork support frame.

[0021] P9. Support the outer steel formwork of the inclined plate and pour concrete. After the inclined plate concrete is poured, tie the formwork to the outer support frame.

[0022] P10. Pour the top slab concrete.

[0023] In step S5, the horizontal spacing and elevation of each symmetrical steel formwork unit are calculated using BIM technology based on the template. After each ring is installed according to the design requirements, the horizontal spacing and elevation of each symmetrical steel formwork unit are checked. Only after it is qualified can the installation of the next ring be carried out.

[0024] In step S5, during the installation of the inner formwork support system, anti-buoyancy treatment is carried out on the inner steel cylinder formwork. The method is as follows: when constructing the bottom slab concrete, high-strength bolts are pre-embedded and installed. When installing the inner steel cylinder formwork, the high-strength bolts are connected to the longitudinal support columns of the steel support truss unit and the bottom of the inner steel cylinder formwork by a manual hoist. The structural support columns under the bottom slab are used to pull the inner steel cylinder formwork to prevent it from floating.

[0025] The internal formwork support system includes steel formwork units, steel support truss units, external scaffolding units, and distribution beam transfer supports. Steel support truss units are set inside the steel formwork units, and external scaffolding units are set outside the steel formwork units. The distribution beam transfer supports provide a flat contact surface for the main keel of the inclined formwork in the steel formwork unit and the distribution beam in the support truss unit.

[0026] The steel formwork unit includes steel formwork, tie rods, and adjustable diagonal braces. The steel formwork is connected to the main keel and the outer concrete through tie rods, and the main keel is connected to the steel support truss unit through adjustable diagonal braces.

[0027] The steel formwork includes steel plates and secondary ribs, with secondary ribs evenly distributed between the two steel plates.

[0028] The pull rod includes a climbing cone and a pull rod body, with the pull rod body sleeved on the climbing cone.

[0029] The steel support truss unit includes a main support truss upright, a horizontal support truss, a diagonal support truss, and a distribution beam. The horizontal support truss is vertically connected to the main support truss upright, and the diagonal support truss is inclinedly connected to the horizontal support truss and the main support truss upright at opposite corners. The main support truss upright includes a circular tube and an adjustable support head. The distribution beam is connected to the top of the main support truss upright through the adjustable support head connected to the top of the circular tube.

[0030] In step P1, the external scaffolding unit is erected using a disc-lock scaffolding system.

[0031] The beneficial effects of this invention are as follows: This invention employs a method of first constructing the base plate steel formwork, followed by constructing the sidewall and top plate steel formwork ring by ring from the diffuser ring section to the rectangular section. This effectively ensures a proper connection between the base plate and the steel formwork, prevents displacement during steel formwork installation, allows for timely verification of the channel's inner diameter, accelerates construction progress, reduces construction defects, and improves work efficiency, thus meeting the formwork requirements at the octagonal-to-quadrilateral main diffuser section. BIM engineers participate in the entire process of designing, processing, and installing the internal steel formwork. Applying this method allows for the construction of an internal formwork support system that meets construction accuracy requirements, ensuring smooth construction completion and effectively solving technical construction challenges. Attached Figure Description

[0032] Figure 1 is an elevation view of the template and keel support of the present invention;

[0033] Figure 2 is a planar layout diagram of the keel and support of the present invention;

[0034] Figure 3 is a diagram of the rectangular side segment template and keel support of the present invention;

[0035] Figure 4 is a diagram of the variable cross-section section template and keel support of the present invention;

[0036] Figure 5 is a diagram of the octagonal segment template and keel support of the present invention;

[0037] Figure 6 is a schematic diagram of the keel support truss upright structure of the present invention;

[0038] Figure 7 is a schematic diagram of the steel template structure of the present invention;

[0039] Figure 8 is a schematic diagram of the tie rod structure of the present invention;

[0040] Figure 9 is a schematic diagram of the connection between the sub-beam conversion support and the inclined template of the present invention;

[0041] Figure 10 is a schematic diagram of the connection structure between the template, keel support and outer frame of the present invention;

[0042] In the diagram: 1-Steel formwork unit; 11-Steel formwork; 111-Steel plate; 112-Secondary rib; 113-Main keel; 12-Tie rod; 121-Tie rod body; 122-Climbing cone; 13-Adjustable diagonal brace; 2-Steel support truss unit; 21-Longitudinal support column; 211-Round pipe; 212-Adjustable support head; 22-Transverse support column; 23-Support truss diagonal member; 24-Distribution beam; 3-External scaffold unit; 4-Distribution beam conversion support; 5-High-strength bolt; 6-Manual hoist;

[0043] The following will describe in detail, with reference to the accompanying drawings, embodiments of the invention. Detailed Implementation

[0044] The invention will be further described below with reference to the accompanying drawings and embodiments:

[0045] As shown in Figures 1-10, taking the transformation of an octagon into a square as an example:

[0046] The construction method for the concrete internal formwork support system of the diffusion section of an ultra-large wind tunnel includes the following steps:

[0047] S1. Using BIM technology, a full simulation model of the flow channel structure and steel formwork 11 is created based on the construction drawings. Model data is extracted, and the size data of steel formwork 11 is determined piece by piece through precise virtual assembly. Node drawings are generated for the 3D model of each formwork and fastener, showing the elevation of the four corners of each formwork piece in detail. A prefabrication family library of steel formwork 11 is established for the project. Node drawings are generated for the 3D model of each steel formwork 11 and fastener, showing the elevation of the four corners of each steel formwork 11 in detail. The family library information of steel formwork 11 is fed back to the steel formwork 11 processing manufacturer, who directly extracts the model size information of steel formwork 11 for steel formwork 11 processing.

[0048] S2. After the factory finishes processing, the steel formwork 11 is re-verified and assembled using BIM data, and a QR code is affixed. Once the inspection is passed, it is transported to the construction site. After the steel formwork 11 arrives on site, the materials are inspected. The dimensions, flatness, curvature, and chord length of each steel formwork 11 are verified piece by piece according to the QR code data to ensure that the design requirements are met.

[0049] S3. Construction personnel can quickly determine the information and positioning information of steel formwork 11 by scanning the QR code, and quickly complete the precise positioning and installation of steel formwork. They can then carry out on-site positioning and layout of each section of the inner steel formwork 11. When carrying out on-site positioning and layout of each section of the inner steel formwork 11, the distance from the center point of the flow channel to the intersection of each inclined plane is calculated based on the BIM model and CAD drawings of each flow channel section to locate the corresponding section.

[0050] S4. Before installing the internal formwork support system, the BIM engineer uses the internal steel cylinder formwork BIM model to create an installation animation demonstration and provides visual instructions to site management personnel and workers. Workers install the internal formwork support system according to the sequence shown in the animation. The internal formwork support system includes steel formwork unit 1, steel support truss unit 2, external scaffold unit 3, and distribution beam transfer support 4. Steel support truss unit 2 is installed inside steel formwork unit 1, and external scaffold unit 3 is installed outside. The distribution beam transfer support 4 is for the inclined formwork in steel formwork unit 1. The main keel 113 and the distribution beams 24 in the supporting truss unit 2 provide a flat contact surface and are steel plate assemblies; the steel formwork unit 1 includes steel formwork 11, tie rods 12, and adjusting diagonal braces 13. The steel formwork 11 is connected to the main keel 113 and the outer concrete through tie rods 12, and the main keel 113 is connected to the steel supporting truss unit 2 through adjusting diagonal braces 13; the adjusting diagonal braces 13 are adjustable diagonal braces for leveling the formwork. The main keel 113 is made of No. 12 double channel steel. The steel formwork 11 includes steel plate 111 and secondary ribs 112. The thickness of the steel plate 111 is [missing information]. 6mm, secondary ribs 112 are made of No. 8 single channel steel, and secondary ribs 112 are evenly distributed between two steel plates 111; tie rod 12 includes climbing cone 122 and tie rod body 121, tie rod body 121 is sleeved with climbing cone 122, tie rod body 121 is D20 tie rod, and water-stop bolt can be added in the middle; the steel support truss unit 2 includes support truss main upright 21, support truss horizontal bar 22, support truss diagonal bar 23 and distribution beam 24, support truss horizontal bar 22 is vertically connected to support truss main upright 21, and support truss diagonal bar 23 is inclinedly connected to the support truss main upright 21. At the diagonal points of the horizontal support bar 22 and the main support bar 21, the main support bar 21 includes a circular tube 211 and an adjustable support head 212. The circular tube is φ160mm. The horizontal support bar 22 is made of double No. 10 channel steel. The diagonal support bar 23 is made of single No. 12 channel steel. The distribution beam 24 is connected to the top of the main support bar 21 through the adjustable support head 212 connected to the top of the circular tube 211. The distribution beam 24 is used to evenly transfer the top formwork and concrete load to the support bridge. The distribution beam 24 is made of No. 28 I-beam.

[0051] S5. Based on the template, use BIM technology to calculate the horizontal spacing and elevation of each symmetrical steel template unit 1. After each ring is installed according to the design requirements, verify the horizontal spacing and elevation of each symmetrical steel template unit 1. Only after passing the verification can the next ring be installed. After the concrete construction of the bottom plate plane of the polygonal to square main diffusion section and the structural support columns below it is completed and reaches the required strength, position and install the steel template unit 1 and the steel support truss unit 2. During the installation of the inner template support system, anti-buoyancy treatment is carried out on the inner steel cylinder template. The method is as follows: when constructing the bottom plate plane concrete, pre-embed high-strength bolts 5. When installing the inner steel cylinder template, connect the high-strength bolts 5 to the longitudinal support columns 21 of the steel support truss unit 2 and the bottom of the inner steel cylinder template through a manual hoist 6. Use the structural support columns under the bottom plate to pull the inner steel cylinder template to prevent it from floating. The positioning and installation method of steel template unit 1 and steel support truss unit 2 is as follows:

[0052] P1. Erect the external scaffolding unit 3. The external scaffolding unit 3 is erected using a disc-lock scaffolding system. Install the outer bottom plate steel formwork 11, the corresponding outer inclined steel formwork 11 and the inclined external support, and pour the bottom plate concrete of the wind tunnel diffusion section.

[0053] P2. Install the steel formwork unit 1 corresponding to the inner inclined side formwork, and pour the bottom slab concrete horizontally;

[0054] P3. Install the longitudinal support columns 21 and the remaining transverse support columns 22 of the steel formwork unit 1 and steel support truss unit 2 corresponding to the inner wall bottom formwork and side wall formwork as a whole. The longitudinal support columns 21 and transverse support columns 22 are vertically connected to the first horizontal support by bolts at the intersection.

[0055] P4. Install the remaining steel formwork unit 1 and the remaining steel support truss unit 2 of the inner steel cylinder formwork as a whole, and install the horizontal support column 22 and the longitudinal support column 21. The support construction and formwork construction are carried out simultaneously until the second horizontal support.

[0056] P5. Install the steel formwork unit 1 and steel support truss unit 2 corresponding to the top slab formwork;

[0057] P6. To ensure that the cross-sectional dimensions of the steel formwork 11 meet the design requirements, the side wall and top plate steel formwork 11 are installed ring by ring from the octagonal opening to the square opening for each layer.

[0058] P7. After the overall installation of the steel formwork unit 1 and the steel support truss unit 2 of the inner steel cylinder formwork is completed, the lower inclined plate is poured.

[0059] P8. Support the outer steel formwork of the side wall and pour concrete. After the concrete pouring is completed, tie up the outer steel formwork support frame.

[0060] P9. Support the outer steel formwork of the inclined plate and pour concrete. After the inclined plate concrete is poured, tie the formwork to the outer support frame.

[0061] P10. Pour the top slab concrete.

[0062] In the description of the invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention.

[0063] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of the invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0064] In this invention, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0065] The invention has been described above with reference to the accompanying drawings. Obviously, the specific implementation of the invention is not limited to the above-described manner. Any improvements made using the inventive concept and technical solution, or direct application to other situations without modification, are all within the scope of protection of the invention.

Claims

The construction method for the concrete internal formwork support system of the diffusion section of an ultra-large wind tunnel is characterized by, The steps are as follows: S1. Using BIM technology, the flow channel structure and steel formwork (11) are fully simulated and modeled according to the construction drawings. The model data is extracted, and the size data of the steel formwork (11) is determined piece by piece through precise virtual assembly. A family library of prefabricated steel formwork (11) for the project is established. The three-dimensional model of each steel formwork (11) and fastener is used to generate node drawings, and the four corner elevations of each steel formwork (11) are displayed in detail. The family library of steel formwork (11) information is fed back to the steel formwork (11) processing manufacturer, and the manufacturer directly extracts the size information of the steel formwork (11) model for steel formwork (11) processing. S2. After the factory finishes processing, it uses BIM data to verify and assemble the steel formwork (11), and affixes a QR code. After inspection and approval, it is transported to the construction site. After the steel formwork (11) arrives at the site, the materials are inspected. The dimensions, flatness, curvature and chord length of each steel formwork (11) are verified according to the QR code data to ensure that the design requirements are met. S3. On-site positioning and layout of each section of the inner steel formwork (11). When on-site positioning and layout of each section of the inner steel formwork (11), the distance from the center point of the flow channel to the intersection of each inclined plane is calculated based on the BIM model and CAD drawings of each flow channel section to locate the corresponding section. S4. Before the installation of the internal formwork support system, the BIM engineer uses the BIM model of the internal steel cylinder formwork to create an installation animation demonstration and provides a visual briefing to the site management personnel and workers. The workers then install the internal formwork support system according to the sequence of the animation demonstration. S5. After the concrete construction of the bottom plate of the polygonal-to-square main diffusion section and the structural support columns below it is completed and reaches the required strength, the steel formwork unit (1) and the steel support truss unit (2) are positioned and installed. The construction method for the concrete internal formwork support system of the diffusion section of an ultra-large wind tunnel according to claim 1 is characterized in that, The positioning and installation method of the steel formwork unit (1) and the steel support truss unit (2) is as follows: P1. Erect the external frame unit (3), install the outer bottom plate steel formwork, the corresponding outer inclined steel formwork and the inclined external support, and pour the bottom plate concrete of the wind-driven diffusion section; P2. Install the steel formwork unit (1) corresponding to the inner inclined side formwork, and pour the bottom slab concrete horizontally; P3. Install the longitudinal support columns (21) and the remaining transverse support columns (22) of the steel formwork unit (1) and steel support truss unit (2) corresponding to the inner wall bottom formwork and side wall formwork as a whole. The longitudinal support columns (21) and transverse support columns (22) are vertically connected to the first horizontal support by bolts at the intersection. P4. Install the remaining steel formwork unit (1) and the remaining steel support truss unit (2) of the inner steel cylinder formwork as a whole, and install the horizontal support column (22) and the longitudinal support column (21). The support construction and formwork construction are carried out simultaneously until the second horizontal support. P5. Install the corresponding steel formwork unit (1) and steel support truss unit (2) for the top slab formwork; P6. To ensure that the cross-sectional dimensions of the steel formwork (11) meet the design requirements, the side wall and top plate steel formwork (11) are installed ring by ring from the octagonal opening to the square opening for each layer. P7. After the overall installation of the steel formwork unit (1) and the steel support truss unit (2) of the inner steel cylinder formwork is completed, the lower inclined plate is poured. P8. Support the outer steel formwork of the side wall and pour concrete. After the concrete pouring is completed, tie up the outer steel formwork support frame. P9. Support the outer steel formwork of the inclined plate and pour concrete. After the inclined plate concrete is poured, tie the formwork to the outer support frame. P10. Pour the top slab concrete. The construction method for the concrete internal formwork support system of the diffusion section of an ultra-large wind tunnel according to claim 2 is characterized in that, In step S5, the horizontal distance position and elevation of each symmetrical steel template unit (1) are calculated using BIM technology based on the template. After each ring is installed according to the design requirements, the horizontal distance position and elevation of each symmetrical steel template unit (1) are checked. Only after it is qualified can the next ring be installed. The construction method for the concrete internal formwork support system of the diffusion section of an ultra-large wind tunnel according to claim 3 is characterized in that, In step S5, during the installation of the inner formwork support system, the inner steel cylinder formwork is subjected to anti-buoyancy treatment. The method is as follows: when the bottom plate concrete is being constructed, high-strength bolts (5) are pre-embedded and installed. When the inner steel cylinder formwork is installed, the high-strength bolts (5) are connected to the longitudinal support column (21) of the steel support truss unit (2) and the bottom of the inner steel cylinder formwork by a manual hoist (6). The structural support column under the bottom plate is used to pull the inner steel cylinder formwork to prevent it from floating. The construction method for the concrete internal formwork support system of the diffusion section of an ultra-large wind tunnel according to claim 4 is characterized in that, The internal formwork support system includes a steel formwork unit (1), a steel support truss unit (2), an external frame unit (3), and a distribution beam transfer support (4). The steel support truss unit (2) is set inside the steel formwork unit (1), and the external frame unit (3) is set outside the steel formwork unit (1). The distribution beam transfer support (4) provides a flat contact surface for the main keel (113) of the inclined formwork in the steel formwork unit (1) and the distribution beam (24) in the support truss unit (2). The construction method for the concrete internal formwork support system of the diffusion section of an ultra-large wind tunnel according to claim 5 is characterized in that, The steel formwork unit (1) includes a steel formwork (11), tie rods (12) and adjustable diagonal braces (13). The steel formwork (11) is connected to the main keel (113) and the outer concrete through tie rods (12). The main keel (113) is connected to the steel support truss unit (2) through adjustable diagonal braces (13). The construction method for the concrete internal formwork support system of the diffusion section of an ultra-large wind tunnel according to claim 6 is characterized in that, The steel formwork (11) includes a steel plate (111) and secondary ribs (112), with secondary ribs (112) evenly distributed between the two steel plates (111). The construction method for the concrete internal formwork support system of the diffusion section of an ultra-large wind tunnel according to claim 7 is characterized in that, The pull rod (12) includes a climbing cone (122) and a pull rod body (121), with the pull rod body (121) sleeved on the climbing cone (122). The construction method for the concrete internal formwork support system of the diffusion section of an ultra-large wind tunnel according to claim 8 is characterized in that, The steel support truss unit (2) includes a main support truss pole (21), a horizontal support truss pole (22), a diagonal support truss pole (23), and a distribution beam (24). The horizontal support truss pole (22) is vertically connected to the main support truss pole (21). The diagonal support truss pole (23) is obliquely connected to the horizontal support truss pole (22) and the main support truss pole (21) at opposite corners. The main support truss pole (21) includes a round tube (211) and an adjustable support head (212). The distribution beam (24) is connected to the top of the main support truss pole (21) through the adjustable support head (212) connected to the top of the round tube (211). The construction method for the concrete internal formwork support system of the diffusion section of an ultra-large wind tunnel according to claim 9 is characterized in that, In step P1, the external scaffolding unit (3) is erected using a disc-lock scaffolding system.

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