Prefabricated drainage box culvert steel formwork system

Abstract

The invention discloses a prefabricated drainage box culvert steel formwork system which is suitable for the technical field of box culvert formworks. The prefabricated drainage box culvert steel formwork system comprises a pedestal, an outer formwork assembly and an inner formwork assembly. The inner formwork assembly comprises an inner formwork supporting system, a walking system and a hydraulic system. The walking system comprises a main beam and inner mold supports, the two sides of the pedestal are each provided with one inner mold support, the main beam is located over the pedestal, the bottoms of the two ends of the main beam are erected on the inner mold supports, supporting frames are arranged at the two ends, within the range between the two inner mold supports, of the main beam, and supporting legs are arranged at the two ends of the transverse bottom of each supporting frame. Each supporting leg is provided with a walking wheel. The inner mold supporting system comprises a plurality of supporting units and a mold retracting device, each supporting unit comprises an inner top mold, an inner side mold, an angle mold and the mold retracting device, and the mold retracting device is controlled by a hydraulic system to stretch out and draw back to adjust the inner side mold and the angle mold to be in place. Hydraulic linkage is combined with the walking system to achieve automatic contraction and transfer, and the internal mold turnover rate is high.

Description

Technical Field

[0001] This invention relates to the field of formwork technology for box culverts in marine water intake and drainage engineering, and particularly to a prefabricated steel formwork system for drainage box culverts. Background Technology

[0002] In the marine water intake and drainage projects of nuclear power plants, box culverts, as key hydraulic structures, play a crucial role in transporting cooling water and balancing the sea level. Especially in the construction of the inner formwork for large-volume concrete box culverts, traditional methods rely on manually erecting full-span scaffolding for inner formwork support and dismantling, which has significant drawbacks: the inner formwork system is assembled from scattered small-area templates, resulting in numerous joints and poor tightness. During concrete pouring, uneven pressure can easily lead to grout leakage, template bulging, or misalignment, causing honeycomb-like pitting on the inner wall and dimensional deviations; manual dismantling requires loosening bolts and knocking apart templates piece by piece, a cumbersome process with the risk of template falling, resulting in low efficiency and significant safety hazards.

[0003] Existing improved technologies, such as CN208250935U, a large-volume concrete support formwork for easy demolding, although employing an integral inner formwork structure that can be moved out as a whole, involve numerous components in its inner formwork fixing mechanism, such as hydraulic cylinders, lead screws, tie beams, and main beams. It still relies on manual adjustment of multi-stage lead screws, resulting in a complex operation process, high manufacturing costs, and difficult maintenance. Furthermore, mechanical failures at the construction site can easily affect efficiency. The inner formwork fixing mechanism uses a high-rigidity internal steel structure frame, which is costly. The supporting frame's traveling legs need to be designed to be robust to meet the support force design requirements, further increasing costs. Moreover, the inner formwork is still prone to deformation during vibration, affecting accuracy. The traveling device under the traveling legs can only be used normally after the bottom of the box culvert has been poured for at least four hours to meet strength requirements before the sliding rails of the traveling device can be installed. This requires two-step construction, significantly increasing the pouring time. Adding sliding rails not only affects the internal quality of the box culvert but also requires a large supporting frame, occupying space, resulting in narrow construction space and affecting other construction procedures.

[0004] Therefore, there is an urgent need for a fully hydraulically driven adaptive internal mold system that can completely eliminate manual intervention through automated shrinkage, multi-directional synchronous adjustment, and rapid assembly and disassembly, thereby solving the core problems of low construction efficiency, uncontrollable quality, and insufficient flexibility of existing technologies in traditional internal mold construction. Summary of the Invention

[0005] The purpose of this invention is to provide a prefabricated drainage culvert steel formwork system to solve the technical problems of low construction efficiency, uncontrollable quality, and insufficient flexibility of traditional internal formwork.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A prefabricated drainage box culvert steel formwork system includes a platform, an outer formwork assembly, and an inner formwork assembly. The inner formwork assembly includes a formwork support system, a walking system, and a hydraulic system.

[0008] The walking system includes a main beam and a walking device. An inner mold support is placed on each side of the platform. The main beam is located directly above the platform and its bottom ends are supported on the inner mold supports. The walking device includes a support frame, support legs and walking wheels. The main beam has support frames at both ends within the range between the two inner mold supports. Each support frame has support legs at both ends of its horizontal bottom. Each support leg is equipped with a walking wheel.

[0009] The internal mold support system includes several support units and a mold-collecting device. Several support units are evenly distributed along the length of the main beam. Each support unit includes an inner top mold, inner side molds, corner molds, and a mold-collecting device. The inner top mold is located on the top surface of the main beam along the cross-section of the main beam. The inner side mold has an inclined section and a vertical section. The two sides of the inner top mold are symmetrically connected to one end of the inclined section of the inner side mold. One end of the vertical section of each inner side mold is symmetrically hinged to the corner mold. The mold-collecting device includes a first mold-collecting cylinder and a second mold-collecting cylinder. The inclined section is opposite to the corner mold, and the first mold-collecting cylinder is located between them. The vertical section is connected to the side of the main beam through the second mold-collecting cylinder. The mold-collecting device is controlled by the hydraulic system to adjust the inner side mold and corner mold into position.

[0010] More preferably, the inner mold support has a built-in jack for adjusting the lifting of the main beam, the top of the inner mold support is provided with a drive roller, and the bottom of the main beam is provided with a slide rail that matches the drive roller; the lateral distance between the inner sides of the two support legs below each support frame is greater than the lateral distance between the outer sides of the two rollers on the inner mold support.

[0011] As a preferred embodiment of the present invention, the hydraulic system includes an oil pump, a control valve group, an oil tank, and oil pipes. The oil pump is connected to the oil inlet of the control valve group via oil pipes, and the oil outlet of the control valve group is connected to the inlet and outlet of the first mold-retracting cylinder and the second mold-retracting cylinder via oil pipes. The extension and retraction movements of the first mold-retracting cylinder and the second mold-retracting cylinder are adjusted by the control valve group.

[0012] As a preferred embodiment of the present invention, a box culvert foundation formed by steel reinforcement binding on the pedestal is constructed between the outer mold assembly and the inner mold assembly. The outer mold assembly includes an outer mold truss and an outer template. The outer template is fixedly connected to one side of the outer mold truss to form a single outer mold. The single outer molds are symmetrically arranged on both sides of the box culvert foundation. The outer template is close to the box culvert foundation. The two single outer molds on both sides of the box culvert foundation are connected to the pedestal by a pull rod. The height of the side of the outer mold truss close to the outer template is greater than the top surface of the box culvert foundation. The outer mold trusses on both sides of the box culvert foundation are fixed by an upper pull rod.

[0013] As a preferred embodiment of the present invention, the outer mold assembly further includes a pedal and a handrail, the pedal being laid on the top surface of the outer mold truss, and the handrail being erected on the outer side of the outer mold truss.

[0014] As a preferred technical solution of the present invention, it further includes end molds, which are disposed at both ends of the inner mold assembly along the length direction of the precast drainage box culvert, and their width is flush with the two side edges of the outer mold assembly; the end molds have holes that are consistent with the inner cavity of the precast drainage box culvert, and the inner cavity of the precast drainage box culvert is supported by the inner mold assembly; the two ends of the platform are provided with platform embedded plate anchor bars, and the outer side of the platform embedded plate anchor bars is fixed with a pre-embedded pad plate, and the pre-embedded pad plate is fixed with an extension frame, which is used to support the end molds, and the end molds are fixedly connected to the extension frames by fasteners.

[0015] More preferably, a number of pre-embedded parts are provided at the center line of the platform for installing auxiliary supports. The auxiliary supports are used to support the transfer of the inner mold assembly to the next platform when the inner mold assembly is in the moving state during demolding.

[0016] More preferably, the auxiliary support includes a support body, guide wheels, and a vertical frame. The vertical frame includes a protective sleeve and a tie rod. One end of the tie rod is fixedly connected to an embedded part by a fastener, and the other end is fixedly connected to the support body. The tie rod is covered with a protective sleeve. Guide wheels are installed at the top of both sides of the support body. The guide wheels match the pre-set slide rails at the bottom of the main beam.

[0017] As a preferred technical solution of the present invention, it further includes an inner mold auxiliary support device for providing auxiliary support to the support unit during formwork erection. The inner mold auxiliary support device includes vertical struts, diagonal struts, and transverse struts. Vertical struts on a platform are provided on both sides of the main beam below the inner top mold. The diagonal struts are located between the corner mold and the bottom of the main beam. A pair of symmetrical inner molds are supported by the transverse struts. The precast drainage culvert is a double-cavity structure, with the inner mold assembly installed in each cavity. The inner mold auxiliary support device is installed in the double-cavity structure on the same cross-section.

[0018] As a preferred embodiment of the present invention, the main beam has a plurality of material discharge holes evenly distributed along its length, the material discharge holes serving as concrete pouring inlets, and the material discharge holes are provided with movable cover plates.

[0019] In summary, compared with the prior art, the beneficial effects of the present invention are:

[0020] This invention achieves efficient and precise control of precast drainage box culvert construction through a fully hydraulic drive and modular design. The inner mold is designed as an integral steel mold, controlled by multiple sets of hydraulic cylinders. The hydraulic system links the first and second mold-retracting cylinders, synchronously adjusting the expansion and contraction of the inner and corner molds. This achieves synchronous three-dimensional contraction of the inner and corner molds, i.e., inward and downward movement. Combined with the lifting and lowering of the inner mold support jacks and the coordination of the drive roller slide, it can be completely separated from the concrete surface and lifted out as a whole without the need for piece-by-piece dismantling. This achieves self-adaptive positioning of the inner mold assembly and smooth transfer after demolding, significantly improving the formwork turnover efficiency. The bottom of the main beam integrates a track and a walking device, which can be automatically transferred between multiple precast pedestals via motor drive, without disassembly or secondary assembly. The outer mold assembly is symmetrically fastened with lower and upper tie rods to form a rigid whole, and is equipped with pedals and handrails to create a safe operating platform. The end mold is precisely positioned through pre-embedded extension frames, and the evenly distributed discharge holes on the main beam ensure uniform concrete pouring. The system features redundant design of internal mold auxiliary support, guide wheel slide matching for movement, and reusable steel formwork structure, overcoming the problems of grout leakage and formwork bulging in traditional construction. While ensuring high-precision forming of the inner wall of the box culvert, it reduces manual labor dependence by more than 30%, making it particularly suitable for large-scale prefabrication projects of box culverts with high standards such as nuclear power plants, achieving a comprehensive improvement in quality, efficiency, and safety. Attached Figure Description

[0021] Figure 1 This is a structural schematic diagram of the prefabricated drainage box culvert steel formwork system of the present invention;

[0022] Figure 2a for Figure 1 CC cross-section diagram;

[0023] Figure 2b for Figure 1 DD cross-section diagram;

[0024] Figure 3 for Figure 1 AA section view of the inner mold assembly;

[0025] Figure 4 for Figure 1 BB section view of the inner mold assembly;

[0026] Figure 4a for Figure 1 BB cross-sectional view of the inner mold assembly in the demolding state;

[0027] Figure 5This is a magnified view of a portion of the pedestal;

[0028] Figure 6 This is a schematic diagram of the auxiliary support structure;

[0029] In the diagram: 100-Precast drainage box culvert, 1-Inner mold support, 10-Jack, 11-Drive roller, 2-Inner mold assembly, 201-First mold closing cylinder, 202-Second mold closing cylinder, 21-Inner mold support system, 210-Inner top mold, 211-Inner side mold, 212-Corner mold, 213-Horizontal strut, 214-Diagonal strut, 22-Walking system, 220-Walking device, 221-Support frame, 222-Support leg, 223-Walking wheel, 224-Discharge hole, 3-Platform, 4-Embedded part, 40-Upright frame, 41-Protective cylinder, 42-Upright tie rod, 43-Support body, 44-Guide wheel, 5-End mold, 6-Outer mold assembly, 61-Outer template, 62-Outer mold truss, 7-Handrail, 8-Pedal, 9-Upper tie rod, 90-Lower tie rod. Detailed Implementation

[0030] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0031] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0032] like Figures 1-6 As shown, a prefabricated drainage box culvert steel formwork system includes a base 3, an outer formwork assembly 6, and an inner formwork assembly 2. The inner formwork assembly 2 includes an inner formwork support system, a walking system 22, and a hydraulic system.

[0033] The walking system 22 includes a main beam and a walking device 220. An inner mold support 1 is placed on each side of the platform 3. The main beam is located directly above the platform 3 and its bottom ends are supported on the inner mold support 1. The walking device 220 includes a support frame 221, support legs 222 and walking wheels 223. The main beam has support frames 221 at both ends within the range between the two inner mold supports 1. Each support frame 221 has support legs 222 at both ends of its horizontal bottom. Each support leg 222 is equipped with a walking wheel 223.

[0034] The inner mold support system 21 includes several support units and a mold-collecting device. Several support units are evenly distributed along the length of the main beam. Each support unit includes an inner top mold 210, an inner side mold 211, a corner mold 212, and a mold-collecting device. The inner top mold 210 is located on the top surface of the main beam along the cross-section of the main beam. The inner side mold 211 has an inclined section and a vertical section. The two sides of the inner top mold 210 are symmetrically connected to one end of the inclined section of the inner side mold 211. One end of the vertical section of each inner side mold 211 is symmetrically hinged to the corner mold 212. The mold-collecting device includes a first mold-collecting cylinder 201 and a second mold-collecting cylinder 202. The inclined section is opposite to the corner mold 212, and the first mold-collecting cylinder 201 is provided between them. The vertical section is connected to the side of the main beam through the second mold-collecting cylinder 202. The mold-collecting device is controlled by the hydraulic system to adjust the inner side mold 211 and the corner mold 212 into position.

[0035] It should be noted that in this embodiment, the inclined section and the vertical section form a 135-degree angle, and the corner mold is opposite to the inclined section, that is, the corner mold and the vertical section also form a 135-degree angle. The upper hinge point of the first mold-retracting cylinder 201 is set at the midpoint of the inclined section, and the lower hinge point is set at the midpoint of the corner mold. The first mold-retracting cylinder 201 is parallel to the vertical section. The lower hinge point of the second mold-retracting cylinder 202 is set at the midpoint of the vertical section. With the main beam as the center line, the first and second mold-retracting cylinders on the left and the first and second mold-retracting cylinders on the right are symmetrical to each other. The whole structure is designed as a symmetrical structure to ensure that the corner mold and the inner mold are adjusted to shrink in place at the same time.

[0036] like Figure 3 As shown, the inner mold support 1 has a built-in jack 10 for adjusting the lifting of the main beam. The top of the inner mold support 1 is provided with a drive roller 11, and the bottom of the main beam is provided with a slide rail that matches the drive roller 11. The lateral distance between the inner sides of the two support legs 222 under each support frame 221 is greater than the lateral distance between the outer sides of the two rollers on the inner mold support 1.

[0037] In this embodiment, the main beam is directly erected on two inner formwork supports, spanning the entire box culvert cavity. The weight of the main beam rests on the inner formwork supports, and the main beam does not contact the box culvert cavity during installation and pouring. There is no need to lay sliding rails for transfer; instead, the main beam is moved by drive rollers on the inner formwork supports. This simplifies the inner formwork support system, requiring only multiple support units along the main beam's axial direction. Each support unit serves as a symmetrical support structure for the inner formwork assembly, reducing the need for complex frames and lowering the rigidity requirements of the support system, thus increasing construction tolerance. This embodiment uses a main beam combined with inner formwork supports, eliminating the need for additional structures such as sliding rails and complex frames, significantly reducing material and construction costs. Furthermore, it makes formwork installation and dismantling more convenient, saving labor and time costs.

[0038] The steel formwork system in this embodiment features a hydraulically controlled, integrally retractable inner formwork. Multiple hydraulic cylinders work in tandem to achieve synchronous three-dimensional retraction of the inner formwork 211 and corner formwork 212, allowing for complete separation from the concrete surface before hoisting out as a whole, eliminating the need for piece-by-piece dismantling. The bottom of the inner formwork integrates a track and a walking device 220, which, driven by a motor, allows for automatic transfer between multiple precast platforms without disassembly or secondary assembly. Unlike existing technologies that rely on manual formwork removal and handling, this embodiment achieves full automation of the "retraction-transfer-deployment" process through hydraulic linkage combined with the walking system 22.

[0039] In a preferred embodiment, the hydraulic system includes an oil pump, a control valve group, an oil tank, and oil pipes. The oil pump is connected to the inlet of the control valve group via oil pipes, and the outlet of the control valve group is connected to the inlet and outlet of the first mold-retracting cylinder 201 and the second mold-retracting cylinder 202 via oil pipes. The extension and retraction movements of the first mold-retracting cylinder 201 and the second mold-retracting cylinder 202 are adjusted by the control valve group.

[0040] The above-mentioned hydraulic control logic ensures that the cylinders retract in the order of "corner mold 212 retracting first, followed by inner mold 211," preventing template jamming. A sliding track is integrated at the bottom of the main beam, and motor-driven wheel sets are installed on the inner mold supports, allowing for remote positioning during transfer. Demolding time is reduced from the traditional 4 hours to 1 hour, and template turnover rate is increased by 300%.

[0041] In a preferred embodiment, a box culvert foundation formed by steel reinforcement binding on the pedestal 3 is constructed between the outer mold assembly 6 and the inner mold assembly 2. The outer mold assembly 6 includes an outer mold truss 62 and an outer template 61. The outer template 61 is fixedly connected to one side of the outer mold truss 62 to form a single outer mold. The single outer molds are symmetrically arranged on both sides of the box culvert foundation. The outer template 61 is close to the box culvert foundation. The two single outer molds on both sides of the box culvert foundation are connected to the pedestal 3 by a pull rod 90. The height of the side of the outer mold truss 62 close to the outer template 61 is greater than the top surface of the box culvert foundation. The outer mold trusses 62 on both sides of the box culvert foundation are fixed by an upper pull rod 9.

[0042] In a preferred embodiment, the outer mold assembly 6 further includes a pedal 8 and a handrail 7. The pedal 8 is laid on the top surface of the outer mold truss 62, and the handrail 7 is erected on the outside of the outer mold truss 62.

[0043] In a preferred embodiment, this model further includes end molds 5, located at both ends of the inner mold assembly 2 along the length of the precast drainage culvert 100, with their width flush with the two side edges of the outer mold assembly 6. The end molds 5 have holes that correspond to the inner cavity of the precast drainage culvert, and the inner cavity of the precast drainage culvert is supported by the inner mold assembly 2. The two ends of the platform 3 are provided with platform embedded plate anchor bars, and embedded pads are fixed to the outside of the platform embedded plate anchor bars. An extension frame is fixed to the embedded pad, and the extension frame is used to support the end molds 5. The end molds 5 are fixedly connected to the extension frames by fasteners.

[0044] Furthermore, several embedded parts 4 are provided at the center line of the platform 3 for installing auxiliary supports. The auxiliary supports are used to support the transfer of the inner mold assembly 2 to the next platform 3 when the inner mold assembly 2 is in the moving state during demolding.

[0045] Furthermore, the auxiliary support includes a support body 43, guide wheels 44, and a support frame 40. The support frame 40 includes a protective sleeve 41 and a tie rod 42. One end of the tie rod 42 is fixedly connected to the embedded part 4 by a fastener, and the other end is fixedly connected to the support body 43. The tie rod 42 is covered with a protective sleeve 41. Guide wheels 44 are installed on the top of both sides of the support body 43. The guide wheels 44 are matched with the preset slide rails at the bottom of the main beam.

[0046] In a preferred embodiment, this method further includes an internal mold auxiliary support device, such as... Figure 2b As shown, the inner mold auxiliary support device is used to provide auxiliary support for the support unit during formwork erection. The inner mold auxiliary support device includes vertical support rods, diagonal support rods 214 and transverse support rods 213. Vertical support rods (not shown in the figure) are provided on both sides of the main beam below the inner top mold 210 and are erected on the platform 3. The diagonal support rods 214 are located between the corner mold 212 and the bottom of the main beam. A pair of symmetrical inner side molds 211 are supported by the transverse support rods 213. The precast drainage culvert is a double-cavity structure, and the inner mold assembly is installed in each cavity. The inner mold auxiliary support device is installed in the double-cavity structure with the same cross-section.

[0047] Combination Figure 1 , Figure 2a and Figure 2bIn this embodiment, the inner mold auxiliary support device and the mold closing device are arranged at intervals along the direction of the precast drainage box culvert. That is, each support unit is equipped with a mold closing device or an auxiliary support device. Depending on the specific project requirements, the interval arrangement can be a combination of two mold closing devices and one auxiliary support device, or a combination of one mold closing device and one auxiliary support device. There are also many other combination methods, which will not be described in detail here. In this embodiment, the inner mold assembly is applied to a double-cavity precast drainage box culvert. Each cavity uses a combination of a mold-collecting device and an inner mold auxiliary support device arranged at intervals. The two cavities in the same cross-sectional plane are equipped with the same device. That is, a pair of symmetrical inner mold auxiliary support devices are set between the two cavities in the same cross-section. In the same cross-section, such as the DD cross-section, the auxiliary support devices adopted adopt a symmetrical force design in the corresponding cross-sectional plane. In the inner mold auxiliary support device of a single cavity, the two opposite inner molds are supported by transverse struts, and the two symmetrical corner molds are symmetrically supported by diagonal struts. The whole forms a symmetrical force system to offset the lateral load. Unlike the existing technology, it does not rely on a complex internal frame, which reduces material costs and significantly improves the control of lateral deformation.

[0048] Considering that the overall support system needs to meet the stress balance during pouring, the existing internal formwork is prone to bending deformation under axial force. It is necessary to control the deformation by adding a high-rigidity internal formwork fixing mechanism, but the cost will increase significantly. In this embodiment, the internal formwork assembly forms a support system for the box culvert cavity by setting formwork collection devices and auxiliary support devices at axial intervals on the main beam. Each auxiliary support device forms a symmetrical support ring for the box culvert cavity. The dense distribution forms a tight ring-like stress distribution, reducing the deformation caused by local point stress. This achieves the requirements for formwork flatness and deformation control at a lower cost. At the same time, this embodiment does not rely on concrete strength for stress conversion, but directly optimizes the stress path through structural design.

[0049] The internal formwork auxiliary support device used in this embodiment forms a three-dimensional statically determinate structure through vertical struts in the vertical dimension, diagonal struts 214 in the diagonal dimension, and transverse struts 213 in the horizontal dimension, constructing an independent and stable system to resist the pouring load. Specifically, the vertical struts are directly erected on the construction platform, providing vertical support for the inner top formwork 210, transferring the self-weight of the concrete and the construction load to the foundation, and preventing the formwork from settling. The measured settlement is ≤2mm, which is better than the 8-10mm without a support system, confirming that the vertical bearing capacity is strengthened; one end of the corner formwork is hinged to the vertical section, and the other end of the corner formwork is inclined inward as a free end. The inclined struts form a 45° angle with the ground. The hinge point of one end of the inclined strut to the corner formwork is located at the midpoint of the corner formwork, and the hinge point of the other end of the inclined strut is located at the midpoint of the bottom of the main beam in the same section. The inclined struts form an inclined support angle of 45° to 60° with the ground. With the main beam as the centerline, the two symmetrical inclined struts form a triangular structure to resist lateral pressure. Through mechanical decomposition, the lateral pressure is converted into axial force, reducing the risk of formwork bulging. Lateral displacement is controlled to ≤3mm / m. The transverse struts 213 symmetrically connect the inner formwork on both sides to form a closed frame, suppressing the horizontal vibration and torsional deformation of the formwork, and increasing the overall stiffness by more than 50%.

[0050] In this preferred embodiment, the main beam has a plurality of discharge holes 224 evenly distributed along its length. Each discharge hole 224 serves as a concrete pouring inlet and is equipped with a movable cover plate. Furthermore, to avoid stress concentration caused by square holes, the circular discharge holes 224 with a diameter of 200-300mm are designed with annular reinforcing ribs along their edges.

[0051] The above-mentioned method uses multiple discharge holes 224 evenly distributed along the length direction with a spacing of 2-3m to pour concrete evenly in multiple directions. This allows concrete to be directly injected into the bottom cavity of the box culvert from the top, avoiding aggregate segregation and honeycomb surface defects caused by traditional single-sided pouring. The movable cover plate allows direct observation of the concrete flow state and facilitates adjustment of the vibration point, which is especially suitable for areas with dense reinforcement. It can also be reserved as a remedial channel: if local voids occur, secondary grouting can be done through the nearest discharge hole 224, avoiding demolding and rework and reducing maintenance costs by 70%.

[0052] During the pouring stage, existing technologies require the bottom slab of the box culvert to be poured in advance before the steel formwork is installed, and the formwork can only be installed and dismantled after it reaches the strength design requirements. In contrast, this embodiment allows the bottom slab and side slabs to be poured directly on the box culvert foundation after the steel formwork system is installed. Only one curing is required, which greatly shortens the construction period. There is no need to lay sliding rails on the bottom slab of the box culvert in advance, which simplifies the construction process.

[0053] After the poured concrete reaches the demolding strength, the outer mold assembly 6 and end mold 5 are demolded first, followed by the inner mold assembly 2. The specific process of demolding the inner mold assembly 2 using a pull-out method and transferring it to the next support is as follows: First, the auxiliary supports are removed. The hydraulic system controls the demolding device to first retract the corner mold 212 and then immediately retract the inner mold 211. The jacks 10 of the inner mold support 1 are adjusted to fall, causing the inner mold assembly 2 to descend. The inner top mold 210 separates from the inner top wall of the precast drainage culvert 100, completing the demolding of the inner top mold 210. 2. The main beam transitions from the demolding state to the walking state via the walking system 22. The front end of the main beam moves to the next precast platform, while the rear inner mold support 1 descends and detaches from the main beam. The walking wheels 223 at the rear end of the main beam drive into the surface of the bottom plate of the precast drainage culvert cavity, allowing the inner mold assembly 2 to continue moving forward. The front inner mold support 1 is adjusted to make the main beam horizontal. Auxiliary supports are erected at the pre-embedded points on the next platform. The front end of the main beam passes the auxiliary supports until it reaches its position, and the inner mold assembly 2 moves laterally to the next platform. In a multi-platform collaborative production line, the inner mold assembly 2 circulates between multiple precast platforms via the walking system 22. After demolding, the outer mold assembly 6 is immediately hoisted to the adjacent platform, staggering its operation time with that of the inner mold assembly 2, thus forming continuous production.

[0054] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. A precast drainage box culvert steel formwork system, comprising a base, an outer formwork assembly, and an inner formwork assembly, characterized in that: The inner mold assembly includes an inner mold support system, a walking system, and a hydraulic system; The walking system includes a main beam and a walking device. An inner mold support is placed on each side of the platform. The main beam is located directly above the platform and its bottom ends are supported on the inner mold supports. The walking device includes a support frame, support legs and walking wheels. The main beam has support frames at both ends within the range between the two inner mold supports. Each support frame has support legs at both ends of its horizontal bottom. Each support leg is equipped with a walking wheel. The internal mold support system includes several support units and a mold-collecting device. Several support units are evenly distributed along the length of the main beam. Each support unit includes an inner top mold, inner side molds, corner molds, and a mold-collecting device. The inner top mold is located on the top surface of the main beam along the cross-section of the main beam. The inner side mold has an inclined section and a vertical section. The two sides of the inner top mold are symmetrically connected to one end of the inclined section of the inner side mold. One end of the vertical section of each inner side mold is symmetrically hinged to the corner mold. The mold-collecting device includes a first mold-collecting cylinder and a second mold-collecting cylinder. The inclined section is opposite to the corner mold, and the first mold-collecting cylinder is located between them. The vertical section is connected to the side of the main beam through the second mold-collecting cylinder. The mold-collecting device is controlled by the hydraulic system to extend and retract, adjusting the inner side mold and corner mold into position.

2. The prefabricated drainage box culvert steel formwork system according to claim 1, characterized in that: The inner mold support has a built-in jack for adjusting the lifting of the main beam. The top of the inner mold support is equipped with a drive roller, and the bottom of the main beam is equipped with a slide rail that matches the drive roller. The lateral distance between the inner sides of the two support legs under each support frame is greater than the lateral distance between the outer sides of the two rollers on the inner mold support.

3. The prefabricated drainage box culvert steel formwork system according to claim 1, characterized in that: The hydraulic system includes an oil pump, a control valve group, an oil tank, and oil pipes. The oil pump is connected to the oil inlet of the control valve group via oil pipes. The oil outlet of the control valve group is connected to the inlet and outlet of the first mold-retracting cylinder and the second mold-retracting cylinder via oil pipes. The extension and retraction movements of the first mold-retracting cylinder and the second mold-retracting cylinder are adjusted by the control valve group.

4. The prefabricated drainage box culvert steel formwork system according to claim 1, characterized in that: A box culvert foundation, formed by steel reinforcement binding on the pedestal, is constructed between the outer mold assembly and the inner mold assembly. The outer mold assembly includes an outer mold truss and an outer template. The outer template is fixedly connected to one side of the outer mold truss to form a single outer mold. The single outer molds are symmetrically arranged on both sides of the box culvert foundation. The outer template is adjacent to the box culvert foundation. The two single outer molds on both sides of the box culvert foundation are connected to the pedestal by a pull rod. The height of the outer mold truss adjacent to the outer template is greater than the top surface of the box culvert foundation. The outer mold trusses on both sides of the box culvert foundation are fixed by an upper pull rod.

5. A prefabricated drainage culvert steel formwork system according to claim 4, characterized in that: The outer mold assembly also includes a pedal and a handrail. The pedal is laid on the top surface of the outer mold truss, and the handrail is erected on the outside of the outer mold truss.

6. The prefabricated drainage box culvert steel formwork system according to claim 1, characterized in that: It also includes end molds, which are located at both ends of the inner mold assembly along the length of the precast drainage box culvert, and their width is flush with the two side edges of the outer mold assembly; the end molds have holes that are consistent with the inner cavity of the precast drainage box culvert, and the inner cavity of the precast drainage box culvert is supported by the inner mold assembly; the two ends of the platform are provided with platform embedded plate anchor bars, and the outer side of the platform embedded plate anchor bars is fixed with a pre-embedded pad plate, and the pre-embedded pad plate is fixed with an extension frame, which is used to support the end molds, and the end molds are fixedly connected to the extension frames by fasteners.

7. A prefabricated drainage box culvert steel formwork system according to claim 6, characterized in that: Several embedded parts are provided at the center line of the platform for installing auxiliary supports. During the demolding process, when the inner mold assembly is in the moving state, the auxiliary supports are used to support the transfer of the inner mold assembly to the next platform.

8. A prefabricated drainage culvert steel formwork system according to claim 7, characterized in that: The auxiliary support includes a support body, guide wheels, and a vertical frame. The vertical frame includes a protective sleeve and a tie rod. One end of the tie rod is fixedly connected to an embedded part by a fastener, and the other end is fixedly connected to the support body. The tie rod is covered with a protective sleeve. Guide wheels are installed at the top of both sides of the support body. The guide wheels match the pre-set slide rails at the bottom of the main beam.

9. A prefabricated drainage box culvert steel formwork system according to claim 1, characterized in that: It also includes an inner mold auxiliary support device for providing auxiliary support to the support unit during formwork erection. The inner mold auxiliary support device includes vertical struts, diagonal struts, and transverse struts. Vertical struts on a platform are provided on both sides of the main beam below the inner top mold. The diagonal struts are located between the corner mold and the bottom of the main beam. A pair of symmetrical inner molds are supported by the transverse struts. The precast drainage culvert is a double-cavity structure, with the inner mold assembly installed in each cavity. The inner mold auxiliary support device is installed in the double-cavity structure on the same cross-section.

10. A prefabricated drainage box culvert steel formwork system according to claim 1, characterized in that: The main beam has several material discharge holes evenly distributed along its length. These discharge holes serve as concrete pouring inlets and are equipped with movable cover plates.

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