Construction Method of Large Steel Formwork Support System for Cast-in-Place Concrete Side Walls of Subway Stations

Abstract

This invention relates to a construction method for a large steel formwork support system for cast-in-place concrete sidewalls in subway stations, comprising the following steps: pouring the base slab concrete and tying the sidewall reinforcement cage based on the sidewall base; installing spaced pad beams and longitudinal limiting grooves on the base slab, with vertical jacks installed on the pad beams; hoisting the large steel formwork, with hydraulic rods installed inside the foundation pit to support the large steel formwork panel against the top surface; and pouring the sidewall concrete. The beneficial effects of this invention are: the development of a high-precision longitudinal and transverse adjustment technology for the large steel formwork construction; the use of pad beams and sliding beam structures, along with longitudinal and transverse jacks, to achieve high-precision adjustment of the large steel formwork; and the development of three corresponding hydraulic rod installation methods for situations where there is support inside the foundation pit, a reverse-constructed top slab, or neither support inside the foundation pit nor a reverse-constructed top slab exists on the large steel formwork, enabling the large steel formwork panel to be supported and fixed under various conditions, further improving the anti-buoyancy effect.

Description

Technical Field

[0001] This invention belongs to the field of municipal engineering technology, and in particular relates to a construction method for a large steel formwork support system for cast-in-place concrete side walls of subway stations. Background Technology

[0002] With the rapid development of subway construction, the construction of the side walls of the main structure of subway stations has become an increasingly important component, receiving more and more attention. The construction of the side walls of subway station structures has evolved from the initial wooden formwork assembly and small steel formwork construction to large steel formwork construction. Large steel formwork can better control the flatness and verticality of the structural surface, and performs better in terms of economy, aesthetics and environmental protection, thus its application in subway construction projects is becoming more and more widespread.

[0003] However, existing construction technologies for large steel formwork for cast-in-place concrete sidewalls have many technical drawbacks. For example, the support system designed in 202210359476.9, a movable large sidewall steel formwork support system, has a sliding frame between its base and support frame. The sliding frame slides on the base to move the steel formwork toward the wall. However, given the large mass of the assembled steel formwork, moving it only through the sliding frame, which has no power source, after positioning is difficult to meet the process requirements for precision adjustment. Another example is the steel formwork designed in 201910907652.6, a movable assembled sidewall steel formwork and its construction method. It includes a base frame, an adjustment mechanism, a formwork panel, and a measuring module. The adjustment mechanism includes a first adjustment mechanism and a second adjustment mechanism, and the measuring module includes a microcontroller, a first laser measuring module, and a second laser measuring module. However, this adjustment mechanism fails to achieve flexible adjustment of the operating platform and fails to effectively guarantee the anti-buoyancy performance of the entire sidewall steel formwork.

[0004] In view of this, there is an urgent need to invent a construction method for large steel formwork for side walls that is highly stable, efficient in transfer, easy to install and operate, and has outstanding economic and technical benefits. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a construction method for a large steel formwork support system for cast-in-place concrete side walls of subway stations.

[0006] The construction method for this type of large steel formwork support system for cast-in-place concrete side walls in subway stations includes the following steps:

[0007] S1. Pour the bottom slab concrete and tie the side wall reinforcement cage based on the side wall base;

[0008] S2. Install pad beams and longitudinal limiting grooves at intervals on the base plate. The two sets of longitudinal limiting grooves are laid parallel to the side wall, and the pad beams are laid perpendicular to the side wall between the two sets of longitudinal limiting grooves. Vertical jacks are installed on the pad beams.

[0009] S3. Hoisting the large steel formwork: The directional wheels of the large steel formwork are placed in the longitudinal limiting groove. After the vertical jacks adjust the elevation of the large steel formwork, the bottom of the large steel formwork is connected to the pad beam through the sliding beam. After the horizontal jacks are used, the large steel formwork panel is connected to the side of the side wall base.

[0010] S4. Adjust the elevation of the cantilevered operating platform, and set up hydraulic rods and large steel formwork panels to support the top surface of the foundation pit; pour the side wall concrete.

[0011] As a preferred embodiment, in step S1, the bottom slab reinforcement is tied on the foundation pad, the joint dowel bars are reserved at the haunch corner of the bottom slab, the bolts of the longitudinal limiting groove are embedded simultaneously, and the embedded bolts are set horizontally in the adjacent side wall base. After the reinforcement project is accepted, the formwork is erected and the bottom slab concrete is poured. After the bottom slab concrete is demolded and cured, the side wall reinforcement is tied according to the vertical connecting bars reserved in the side wall base.

[0012] Preferably, in step S3, the large steel mold includes a large steel mold panel, a large steel mold support, and a cantilevered operating platform. The large steel mold support is located on the back of the large steel mold panel, and the cantilevered operating platform is located on the top of the large steel mold support. The large steel mold support includes support diagonal braces, support vertical braces, support tie braces, and support bottom horizontal braces. The bottom of the large steel mold support is provided with several support bottom horizontal braces. Except for the two outermost support bottom horizontal braces, each support bottom horizontal brace is provided with a pair of directional wheels at its bottom. The two outermost support bottom horizontal braces are provided with adjusting screws. The adjusting screws are set vertically and their height is adjusted by adjusting nuts. The bottom of the adjusting screws is fixed with a sliding beam, and the sliding beam has symmetrically arranged sliding beam anchor ends on its side.

[0013] Preferably, in step S2, the pad beams are placed between parallel longitudinal limiting grooves, and the pad beams are perpendicular to the longitudinal limiting grooves but do not intersect. The top surface of the pad beams is fully covered with stainless steel composite plates, and a pair of pad beam anchoring ends are provided. The spacing of each set of pad beams is the same as the spacing of the bottom cross braces of the support at both ends of the single-panel large steel formwork support. In step S3, vertical jacks are symmetrically placed at both ends of the pad beams. Their top surfaces act on the bottom cross braces of the support, and their bottom surfaces are provided with PTFE plates that act on the pad beams.

[0014] Preferably, in step S3, the transverse jacks are symmetrically arranged on both sides of the sliding beam and connected to the anchoring end of the pad beam and the anchoring end of the sliding beam, respectively; after the transverse jacks are installed, the position of the large steel formwork is adjusted by the transverse jacks so that the large steel formwork panel abuts against the side of the side wall base.

[0015] As a preferred embodiment, in step S3, when there are two parallel side walls and the distance between the two side walls is less than a certain value, a hydraulic trolley is installed between the two side walls for supporting the formwork on the opposite side. The hydraulic trolley has a trolley steel mold on each side, the trolley steel mold abuts against the side of the side wall base, and the trolley steel mold is anchored to the pre-embedded bolts.

[0016] Preferably, in step S4, the bottom end of the anti-buoyancy tie bar is first welded to the bottom plate joint reinforcement bar, and the anti-buoyancy tie bar is welded upwards around the large steel formwork panel and then welded to the top of the side wall reinforcement cage. The cantilevered operating platform is welded to the telescopic channel steel, which is equipped with pulleys. The telescopic channel steel is connected to the vertical support of the support through the pulleys. The elevation of the cantilevered operating platform is adjusted using the telescopic channel steel. Wooden boards and dense mesh netting are laid on the cantilevered operating platform. The clamps are installed using the support inside the foundation pit. The clamps include the clamp body and the support end plate. The support end plate is set at the bottom of the clamp body. A hydraulic rod is set between the clamp support end plate and the top surface of the large steel formwork panel.

[0017] As a preferred option, the sidewall away from the large steel formwork is provided with a concrete surface layer, retaining piles and a layer in sequence. When there is no internal support in the foundation pit above the large steel formwork, the corbel brackets are installed at equal intervals by setting pre-embedded bars on the retaining piles. The corbel brackets extend horizontally to the top of the large steel formwork, and hydraulic rods are set between the corbel brackets and the top surface of the large steel formwork panel.

[0018] As a preferred option, in step S4, when the foundation pit is constructed using the reverse construction method and there is a reverse construction top plate above the large steel formwork, the tie rod is directly installed on the bottom surface of the reverse construction top plate using anchor bolts to connect with the large steel formwork. The tie rod is equipped with S-shaped connecting hooks at both ends, and the S-shaped connecting hooks at both ends are connected to the anchor bolts and the large steel formwork respectively. The large steel formwork support in the large steel formwork is replaced with a bottom support frame, and the bottom of the bottom support frame is equipped with support feet.

[0019] As a preferred method, after the side wall concrete meets the demolding conditions, loosen all anchoring nodes of the large steel formwork, cut and remove the anti-buoyancy reinforcement bars, dismantle the hydraulic rods, and use the transverse jacks for initial demolding. Then, remove the transverse jacks, lift the sliding beam, and finally move the large steel formwork to the next working surface through the longitudinal limiting groove.

[0020] The beneficial effects of this invention are:

[0021] 1) This invention has developed a construction technology for high-precision adjustment of large steel formwork in both longitudinal and transverse directions. By setting up pad beams and sliding beams, the high-precision adjustment of large steel formwork is achieved by using longitudinal and transverse jacks. The top surface of the pad beams is fully covered with stainless steel composite plates, which can effectively reduce sliding resistance. At the same time, the longitudinal limiting groove can effectively prevent large-angle displacement when the large steel formwork moves. The overall structure can improve the installation accuracy of large steel formwork and is easy to operate.

[0022] 2) This invention develops a liftable cantilever operating platform. By setting a telescopic channel steel with pulleys, the cantilever operating platform can be flexibly lifted and lowered, which solves the problem of insufficient transportation space in underground space for traditional large steel formwork fixed operating platforms. At the same time, it also ensures the operability of the clamps and brackets in this invention.

[0023] 3) This invention developed a tension-internal support top pressure anti-buoyancy reinforcement technology, which effectively solves the problem of large formwork floating during concrete pouring by making full use of the existing structure of the subway station foundation pit to set up anti-buoyancy tie bars and hydraulic rods.

[0024] 4) This invention proposes three corresponding hydraulic rod setting methods for large steel formwork with internal foundation pit support, reverse top plate, and neither internal foundation pit support nor reverse top plate, so as to realize the top support and fixation of large steel formwork panel in various situations, and further improve the anti-buoyancy effect. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the installation positions of the longitudinal and transverse jacks in this invention;

[0026] Figure 2 In this invention Figure 1 Detailed diagram of node A;

[0027] Figure 3 This is a schematic diagram of the installation position of the longitudinal limiting groove in this invention;

[0028] Figure 4 This is a cross-sectional view of the cantilevered operating platform structure in this invention;

[0029] Figure 5 In this invention Figure 4 Detailed diagram of node B;

[0030] Figure 6 This is a top view of the cantilevered operating platform structure in this invention;

[0031] Figure 7 This is a schematic diagram of the internal support installation hydraulic rod structure in this invention;

[0032] Figure 8 This is a schematic diagram of the hydraulic rod structure for mounting the bracket in this invention;

[0033] Figure 9 This is a schematic diagram of the double-sided formwork structure in this invention;

[0034] Figure 10 This is a schematic diagram of the installation of the reverse top plate tie rod of the present invention;

[0035] Figure 11 This is a cross-sectional view of the hydraulic trolley of the present invention;

[0036] Figure 12 This is a longitudinal cross-sectional view of the hydraulic trolley of the present invention.

[0037] In the diagram: 1-Large steel formwork panel; 2-Base plate; 3-Vertical jack; 4-Support beam; 5-Support beam anchoring end; 6-Horizontal jack; 7-Sliding beam anchoring end; 8-Sliding beam; 9-Support diagonal brace; 10-Support vertical brace; 11-Support tie brace; 12-Support bottom horizontal brace; 13-PTFE plate; 14-Stainless steel composite plate; 15-Directional wheel; 16-Longitudinal limiting groove; 17-Pulley; 18-Telescopic channel steel; 19-Wooden board; 20-Platform upright; 21-Dense mesh netting; 22-Cantilevered operating platform; 23-Layer ; 24-Side wall reinforcement cage; 25-Retaining pile; 26-Concrete surface layer; 27-Ring beam; 28-Holding body; 29-In-pit support; 30-Hydraulic rod; 31-Anti-buoyancy tie bar; 32-Embedded bar; 33-Corner bracket; 34-Tie device; 35-Anchor bolt; 36-Reverse top plate; 37-Bottom support frame; 38-Support leg; 39-Hydraulic trolley; 40-Trolley steel mold; 41-Embedded bolt; 42-Side wall base; 43-Adjusting screw rod; 44-Adjusting nut; 45-Support end plate. Detailed Implementation

[0038] The present invention will be further described below with reference to embodiments. The description of the embodiments below is only for the purpose of helping to understand the present invention. It should be noted that those skilled in the art can make several modifications to the present invention without departing from the principle of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0039] Example 1

[0040] As one example, such as Figures 1 to 12 As shown, the construction method of the large steel formwork support system for the cast-in-place concrete side walls of a subway station includes the following steps:

[0041] S1, Construction of base plate 2 and installation of embedded system: Tie the reinforcing bars of base plate 2 on the foundation pad, reserve the joint dowel bars at the axle corner of base plate 2, and simultaneously embed the longitudinal limiting groove 16 bolts. Also, set the embedded bolts 41 horizontally in the adjacent narrow side wall base 42. After the reinforcement project is accepted, set up the formwork and pour the concrete of base plate 2.

[0042] Side wall reinforcement binding: After the concrete of the bottom slab 2 is demolded and cured, the side wall reinforcement is bound according to the vertical connecting bars reserved in the side wall base 42.

[0043] S2, Pad Beam 4 and Longitudinal Limiting Groove 16 Installation: Pad beam 4 and longitudinal limiting groove 16 perpendicular to it are installed at intervals on the concrete base slab 2. The two longitudinal limiting grooves 16 are parallel to each other and the distance from the side wall is always consistent. The spacing of each set of pad beam 4 is the same as the spacing of the bottom horizontal bracing at both ends of the single large steel formwork support. There is no need to install pad beam 4 and longitudinal limiting groove 16 between adjacent narrow side walls.

[0044] S3. Lifting the large steel formwork: The large steel formwork is lifted into place using lifting equipment, and the directional wheel 15 of the large steel formwork is placed in the longitudinal limiting groove 16. After the vertical jack 3 is used to finely adjust the elevation of the large steel formwork, the adjusting screw 43 is lowered by adjusting nut 44 so that the sliding beam 8 abuts against the pad beam 4. After installing the horizontal jack 6, the large steel formwork is finely adjusted so that the large steel formwork panel 1 abuts against the side of the side wall base 42. The hydraulic trolley 39 is directly installed between adjacent narrow side walls. The trolley steel formwork 40 abuts against the side of the side wall base 42 and is anchored with the pre-embedded bolts 41.

[0045] S4. Installation of formwork system: First, weld one end of the anti-buoyancy tie bar 31 to the joint bar of the bottom plate 2, then weld it upward around the large steel formwork panel 1 and to the top of the side wall reinforcement cage 24. Then, use the telescopic channel steel 18 to adjust the elevation of the cantilever operating platform 22, lock it, and lay the wooden plank 19 and dense mesh net 21. Then, use the existing structure in the foundation pit to set up hydraulic rods 30 to support the top surface of the large steel formwork panel 1.

[0046] S5. Pouring side wall concrete: After the formwork system is installed, pour the side wall concrete in layers. The hydraulic trolley 39 can be used to assist in symmetrical pouring between adjacent narrow side walls.

[0047] S6. Formwork system transfer: After the side wall concrete meets the demolding conditions, loosen all anchoring nodes of the large steel formwork, cut and remove the anti-buoyancy tie bar 31, remove the hydraulic rod 30, and use the transverse jack 6 for initial demolding. Then remove the transverse jack 6, loosen the adjusting nut 44 to lift the sliding beam 8, and finally move the large steel formwork to the next working surface through the longitudinal limiting groove 16.

[0048] Example 2

[0049] As another embodiment, such as Figures 1 to 6 , Figure 11 and Figure 12 As shown, this large steel formwork support system for cast-in-place concrete side walls of subway stations includes a base plate 2 and a large steel formwork. The base plate 2 is provided with a side wall base 42 at the bottom of the side wall, and the side wall reinforcement cage 24 is tied to the side wall base 42.

[0050] like Figures 1 to 3 As shown, bolts with pre-embedded longitudinal limiting grooves 16 are embedded in the base plate 2. Pad beams 4 and longitudinal limiting grooves 16 are laid at intervals on the base plate 2. The two sets of longitudinal limiting grooves 16 are laid parallel to the side walls, forming a sliding track for the large steel formwork. Pad beams 4 are laid perpendicular to the side walls between the two sets of longitudinal limiting grooves 16, and vertical jacks 3 are installed on the pad beams 4. The pad beams 4 are perpendicular to the longitudinal limiting grooves 16 but do not intersect them. The top surface of the pad beams 4 is fully covered with stainless steel composite plates 14. The spacing of each set of pad beams 4 is the same as the spacing of the bottom cross braces 12 of the single-panel large steel formwork support at both ends. The vertical jacks 3 are symmetrically arranged at both ends of the pad beams 4, with their top surfaces acting on the bottom cross braces 12 of the support, and their bottom surfaces covered with PTFE plates 13 acting on the pad beams 4.

[0051] The large steel mold is placed on the base plate 2 and includes a large steel mold panel 1, a large steel mold support and a cantilevered operating platform 22. The large steel mold support is located on the back of the large steel mold panel 1 and the cantilevered operating platform 22 is located on the top of the large steel mold support. The large steel mold support includes support diagonal braces 9, support vertical braces 10, support tie braces 11 and support bottom horizontal braces 12. The bottom of the large steel mold support is provided with several support bottom horizontal braces 12. Except for the two outermost support bottom horizontal braces 12, each support bottom horizontal brace 12 is provided with a pair of directional wheels 15 at its bottom. The directional wheels 15 slide in the track formed by the longitudinal limiting groove 16.

[0052] The two outermost support cross braces 12 are equipped with adjusting screws 43. The adjusting screws 43 are vertically set, and the bottom of the adjusting screws 43 is fixed with a sliding beam 8. After the vertical jack 3 is lowered, the sliding beam 8 can be placed on the pad beam 4 by adjusting the screws 43 to fix the support.

[0053] The sliding beam 8 is symmetrically provided with transverse jacks 6 on both sides. Specifically, the sliding beam 8 is symmetrically provided with sliding beam anchor ends 7 on its side, and the top surface of the pad beam 4 is provided with a pair of pad beam anchor ends 5. The two ends of the transverse jacks 6 are fixedly connected to the sliding beam anchor ends 7 and the pad beam anchor ends 5 respectively. The transverse jacks 6 are used to adjust the horizontal position of the large steel mold.

[0054] The large steel formwork panel 1 abuts against the side wall base 42, the large steel formwork bracket is fixed to the back of the large steel formwork panel 1, and the cantilevered operating platform 22 is located on the top of the large steel formwork bracket.

[0055] like Figures 4 to 6 As shown, a telescopic channel steel 18 is welded to the side of the cantilevered operating platform 22 facing the large steel formwork panel 1. The telescopic channel steel 18 is equipped with pulleys 17. The telescopic channel steel 18 is connected to the vertical support 10 of the support through the pulleys 17, which is used to adjust the elevation of the cantilevered operating platform 22. A wooden board 19 is laid on the cantilevered operating platform 22. A platform upright 20 and a dense mesh net 21 are provided on the side of the cantilevered operating platform 22 away from the large steel formwork panel 1.

[0056] like Figure 11 and Figure 12 As shown, when there are two parallel side walls and the distance between the two side walls is less than a certain value, a hydraulic trolley 39 is installed between the two side walls for supporting the formwork on the opposite side. Pre-embedded bolts 41 are arranged horizontally in the base 42 of the adjacent side walls. Trolley steel molds 40 are respectively provided on both sides of the hydraulic trolley 39. The trolley steel molds 40 and the side walls of the base 42 abut against each other, and the trolley steel molds 40 are anchored to the pre-embedded bolts 41.

[0057] It should be noted that the parts in this embodiment that are the same as or similar to those in Embodiment 1 can be referred to each other, and will not be repeated in this application.

[0058] Example 3

[0059] As another embodiment, this third embodiment, based on embodiments one and two, proposes a more specific large steel formwork support system for cast-in-place concrete side walls of subway stations, involving tension-internal bracing top-compression anti-buoyancy reinforcement technology, such as... Figures 7 to 10 As shown.

[0060] like Figure 7 and Figure 10 As shown, a joint insert bar is reserved at the axle corner of the base plate 2. The joint insert bar of the base plate 2 is welded to an anti-buoyancy tie bar 31. The anti-buoyancy tie bar 31 goes up around the large steel formwork panel 1 and is welded to the top of the side wall reinforcement cage 24, pressing down the large steel formwork panel 1.

[0061] On the side of the side wall away from the large steel formwork, a concrete surface layer 26, retaining piles 25 and a layer 23 are provided in sequence. When there is an internal support 29 on the large steel formwork, a clamp is provided on the internal support 29. The clamp includes a clamp body 28 and a support end plate 45. The support end plate 45 is located at the bottom of the clamp body 28. A hydraulic rod 30 is provided between the clamp support end plate 45 and the top surface of the large steel formwork panel 1.

[0062] like Figure 10 As shown, when there is a reverse-construction top plate 36 above the large steel mold, a tie rod 34 is installed on the bottom surface of the reverse-construction top plate 36 using anchor bolts 35. The tie rod 34 has S-shaped connecting hooks at both ends, and the S-shaped connecting hooks at both ends are connected to the anchor bolts 35 and the large steel mold respectively. The large steel mold support in the large steel mold is replaced by a bottom support 37, and the bottom support 37 has a support foot 38 at the bottom.

[0063] like Figure 8 As shown, when there is no internal support 29 or reverse top plate 36 above the large steel formwork, a corbel support 33 is horizontally installed on the outside of the concrete surface layer 26. The corbel support 33 extends horizontally to the top of the large steel formwork, and a hydraulic rod 30 is installed between the corbel support 33 and the top surface of the large steel formwork panel 1.

[0064] It should be noted that the parts in this embodiment that are the same as or similar to those in Embodiments 1 and 2 can be referred to each other, and will not be repeated in this application.

[0065] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

Claims

1. A construction method for a large steel formwork support system for cast-in-place concrete side walls of a subway station, characterized in that, Includes the following steps: S1. Pour the bottom slab concrete and tie the side wall reinforcement cage based on the side wall base; S2. Install pad beams and longitudinal limiting grooves at intervals on the base plate. The two sets of longitudinal limiting grooves are laid parallel to the side wall, and the pad beams are laid perpendicular to the side wall between the two sets of longitudinal limiting grooves. Vertical jacks are installed on the pad beams. S3. Hoisting the large steel formwork: The directional wheels of the large steel formwork are placed in the longitudinal limiting groove. After the vertical jacks adjust the elevation of the large steel formwork, the bottom of the large steel formwork is connected to the pad beam through the sliding beam. After the horizontal jacks are used, the large steel formwork panel is connected to the side of the side wall base. The large steel formwork includes a large steel formwork panel, a large steel formwork support, and a cantilevered operating platform. The large steel formwork support is located on the back of the large steel formwork panel, and the cantilevered operating platform is located on the top of the large steel formwork support. The large steel formwork support includes diagonal braces, vertical braces, tie braces, and bottom horizontal braces. The bottom of the large steel formwork support has several bottom horizontal braces. Each bottom horizontal brace, except for the two outermost bottom horizontal braces, has a pair of directional wheels at its bottom. The two outermost bottom horizontal braces are equipped with adjusting screws. The adjusting screws are vertically set and their height is adjusted by adjusting nuts. A sliding beam is fixed to the bottom of the adjusting screw, and the sliding beam has symmetrically arranged anchor ends on its side. S4. Adjust the elevation of the cantilevered operating platform. Install hydraulic rods for the support inside the pit, with the large steel formwork panel abutting against the top surface. Pour the side wall concrete. First, weld the bottom end of the anti-buoyancy tie bar to the bottom plate joint reinforcement bar. Then, weld the anti-buoyancy tie bar upwards around the large steel formwork panel and to the top of the side wall reinforcement cage. Weld telescopic channel steel to the cantilevered operating platform. The telescopic channel steel is equipped with pulleys and is connected to the vertical support of the bracket through the pulleys. Adjust the elevation of the cantilevered operating platform using the telescopic channel steel. Lay wooden boards and dense mesh netting on the cantilevered operating platform. Install clamps using the support inside the pit. The clamps include the clamp body and the support end plate. The support end plate is set at the bottom of the clamp body. Install hydraulic rods between the clamp support end plate and the top surface of the large steel formwork panel.

2. The construction method of the large steel formwork support system for cast-in-place concrete side walls of subway stations according to claim 1, characterized in that, In step S1, the bottom slab reinforcement is tied on the foundation pad, and the joint dowel bars are reserved at the haunch corner of the bottom slab. The bolts of the longitudinal limiting groove are embedded simultaneously, and the embedded bolts are set horizontally in the adjacent side wall base. After the reinforcement project is accepted, the formwork is erected and the bottom slab concrete is poured. After the bottom slab concrete is demolded and cured, the side wall reinforcement is tied according to the vertical connecting bars reserved in the side wall base.

3. The construction method of the large steel formwork support system for cast-in-place concrete side walls of subway stations according to claim 1, characterized in that, In step S2, the pad beams are placed between parallel longitudinal limiting grooves, and the pad beams are perpendicular to the longitudinal limiting grooves but do not intersect. The top surface of the pad beams is fully covered with stainless steel composite plates, and a pair of pad beam anchoring ends are provided. The spacing of each set of pad beams is the same as the spacing of the bottom horizontal bracing of the support at both ends of the single-panel large steel formwork support. In step S3, vertical jacks are symmetrically placed at both ends of the pad beams. Their top surfaces act on the bottom horizontal bracing of the support, and their bottom surfaces are provided with PTFE plates that act on the pad beams.

4. The construction method of the large steel formwork support system for cast-in-place concrete side walls of subway stations according to claim 3, characterized in that, In step S3, the horizontal jacks are symmetrically arranged on both sides of the sliding beam and connected to the anchoring end of the pad beam and the anchoring end of the sliding beam, respectively. After the horizontal jacks are installed, the horizontal jacks are used to adjust the position of the large steel formwork so that the large steel formwork panel abuts against the side of the side wall base.

5. The construction method of the large steel formwork support system for cast-in-place concrete side walls of subway stations according to claim 1, characterized in that, The side wall away from the large steel formwork is provided with a concrete surface layer, retaining piles and a layer in sequence. When there is no support in the foundation pit above the large steel formwork, the corbel brackets are installed at equal intervals by setting pre-embedded bars on the retaining piles. The corbel brackets extend horizontally to the top of the large steel formwork, and hydraulic rods are set between the corbel brackets and the top surface of the large steel formwork panel.

6. The construction method of the large steel formwork support system for cast-in-place concrete side walls of subway stations according to claim 1, characterized in that, In step S4, when the foundation pit is constructed using the reverse construction method and there is a reverse construction top plate above the large steel formwork, the tie rod is directly installed on the bottom surface of the reverse construction top plate using anchor bolts to connect with the large steel formwork. The tie rod is equipped with S-shaped connecting hooks at both ends, and the S-shaped connecting hooks at both ends are connected to the anchor bolts and the large steel formwork respectively. The large steel formwork support in the large steel formwork is replaced with a bottom support frame, and the bottom of the bottom support frame is equipped with support feet.

7. The construction method of the large steel formwork support system for cast-in-place concrete side walls of subway stations according to claim 1, characterized in that, After the side wall concrete meets the demolding conditions, loosen all anchoring nodes of the large steel formwork, cut and remove the anti-buoyancy reinforcement bars, dismantle the hydraulic rods, and use horizontal jacks for initial demolding. Then remove the horizontal jacks, lift the sliding beam, and finally move the large steel formwork to the next working surface through the longitudinal limiting groove.

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