A precast box girder maintenance method

Abstract

This invention relates to a method for curing precast box girders, including: A) curing the top surface of the box girder; B) curing the sides of the box girder: spraying water on the two exposed sides of the box girder; A includes: A1) roughening: forming several longitudinally extending grooves on the partially set but not yet cured surface of the box girder, with the grooves parallel to each other; A2) covering with a film; A3) tensioning; A4) watering: pouring water onto the plastic film; A5) covering with geotextile; A6) heat preservation; A7) removing the covering layer; water-retaining flanges are provided on both sides of the upper surface of the box girder perpendicular to the direction of the groove extension, and the water in A4 submerges the portion of the box girder located between the water-retaining flanges. This invention has the advantages of being able to perform zoned curing of the box girder, curing without the box girder needing to be cured, and good tension of the plastic film, solving the problems of existing box girder curing methods that cannot be performed in zones and that curing can only be carried out after the box girder has cured.

Description

Technical Field

[0001] This invention relates to the field of road and bridge construction technology, and in particular to a method for the maintenance of precast box girders. Background Technology

[0002] During road construction, bridges are sometimes necessary. One method of bridge construction involves building piers and abutments, installing crossbeams on the piers, rapidly prefabricating box girders between the crossbeams, and then casting reinforced concrete onto the box girders. The box girder prefabrication process involves building a steel reinforcement cage inside the outer formwork of the box girder, placing the box girder core mold inside the steel reinforcement cage, pouring concrete, and after the concrete has solidified, removing the side and end formwork of the outer formwork for curing. After curing, the core mold is then removed. The existing prefabricated box girder manufacturing process has the following shortcomings: it cannot perform zoned curing of the box girder; the side and end formwork can only be removed for geotextile covering after complete curing, requiring multiple curing steps to prevent moisture loss, which is time-consuming and prolongs the process; and removing the box girder core mold is laborious. Summary of the Invention

[0003] This invention aims to provide a precast box girder curing method that enables zoned curing of box girders, allows curing without the need for box girder curing, and provides good plastic film tension. This solves the problems of existing box girder curing methods that cannot be carried out in zones and that curing can only be performed after the box girder has cured.

[0004] The above technical problems are solved by the following technical solution: A method for curing precast box girders, characterized by including: A. Curing the top surface of the box girder; B. Curing the sides of the box girder: spraying water on the two exposed sides of the box girder; A includes: A1. Roughening: forming several longitudinally extending grooves on the surface of the box girder that has initially set but not yet cured, with the grooves parallel to each other; A2. Covering with film: covering the upper surface of the box girder with a plastic film; A3. Tensioning: inserting several cables through the plastic film into the grooves, with the cables extending along the direction of the grooves, and tensioning the plastic film during the insertion of the cables into the grooves; A4. A5. Watering: Pour water onto the plastic film; A6. Covering with geotextile: Cover the box girder with geotextile over the plastic film; A7. Insulation: Heat the water on the plastic film by energizing the cable and keep it at a constant temperature; A8. Removing the covering layer: Collect the geotextile for reuse, evaporate the water on the plastic film, and energize the cable until the temperature generated by the cable is higher than the melting point of the plastic film, thus melting and burning the plastic film; Water-retaining flanges are provided on both sides of the upper surface of the box girder perpendicular to the extension direction of the trench. The water in A4 submerges the part of the box girder located between the water-retaining flanges.

[0005] Preferably, steps A and B are achieved using a curing chamber and a box girder top surface curing device. The box girder curing chamber is equipped with a longitudinal guide rail for transporting the box girder into the chamber. A bottom formwork supporting the box girder is mounted on the longitudinal guide rail via bottom formwork wheels. The cast box girder lies on the bottom plate in a longitudinally extending state. An upper longitudinal shaft and a lower longitudinal shaft are rotatably connected to the two transverse side walls of the curing chamber, and a longitudinal water supply pipe is fixedly connected to each. An upper sealing plate extending longitudinally is provided on the upper longitudinal shaft, and a lower sealing plate extending longitudinally is provided on the lower longitudinal shaft. The longitudinal water supply pipe is located between the upper and lower longitudinal shafts. Between the rotating shafts, longitudinal water supply pipes are equipped with spray heads distributed longitudinally for spraying water onto the side surfaces of the box girder located in the curing chamber; the box girder top surface curing device includes a suspension base frame suspended above the track via a suspension frame, the suspension base frame is equipped with a crossbar, several rake teeth connected to the crossbar and distributed laterally with their lower ends extending downward beyond the crossbar, and a rake tooth lifting mechanism that drives the crossbar to raise and lower, causing the rake teeth to extend downward beyond the suspension base frame; the suspension base frame is also equipped with a film covering mechanism, a watering mechanism, a line laying mechanism, and a geotextile covering mechanism located in front of the crossbar, and a mechanism connected to the suspension base frame via a swing arm. A horizontally extending roller extends forward. During curing, the plastic film is supported by a covering mechanism, the geotextile by a covering geotextile mechanism, and the cable rolls with the same number of rake teeth by a laying mechanism. When the box girder passes under the suspended base frame, the rake tooth lifting mechanism drives the crossbar to descend until the rake teeth insert into the top surface of the box girder to a set depth. This fixes one end of the plastic film supported by the covering mechanism, one end of the geotextile supported by the covering geotextile mechanism, and one end of the cable rolls supported by the laying mechanism to one end of the box girder along its length. The cables are distributed laterally, positioned above the plastic film, and aligned one-to-one with the rake teeth. The roller presses down on the plastic film. The cable is positioned above and below the geotextile. Rake teeth form grooves on the box girder. A plastic film is placed over the box girder. The cable is pressed into the groove by a roller through the plastic film. Water is sprayed onto the plastic film by a watering mechanism. The geotextile is then placed over the plastic film and covers the cable, thus completing steps A1 to A5. After the box girder enters the curing chamber, the upper longitudinal shaft is rotated so that the upper sealing plate seals against the upper end of the side surface of the box girder. The lower longitudinal shaft is rotated so that the lower sealing plate seals against the side surface of the bottom template. Water is sprayed onto the side of the box girder through a sprinkler head, thus achieving step B. Steps A6 and A7 are then performed in the curing chamber. This technical solution allows for zoned curing of the top surface and two sides of the box girder to meet the different curing needs of different parts. During the curing of the upper surface of the box girder, roughening, membrane covering, cable threading, water spraying, and geotextile covering can be completed in one step, shortening the curing process and improving efficiency. It reduces the problems of uneven surface or lack of membrane curing in some areas caused by manual paving, thereby reducing moisture loss from the box girder and preventing issues such as loose sand exposure or even cracks caused by strong winds. The cables can be easily pressed into the trench.The cable pressing into the trench can tighten the plastic film. Setting up the plastic film can reduce moisture loss and save water during curing. Covering the film first allows the outer formwork to be removed and the geotextile to be covered after the concrete has initially set, saving time waiting for curing.

[0006] Preferably, the film covering mechanism includes a film roll rotatably connected to a suspension base and a film unloading motor that drives the film roll to rotate; the film roll is detachably connected to the suspension base. This provides a specific technical solution for the film covering mechanism.

[0007] Preferably, the suspension base has a first column and a second column arranged opposite to each other. The film roll is located between the first and second columns, and the film-dispensing motor is located outside the first column. The first column has a shaft mounting hole, and an outer flange is bolted to the outside of the shaft mounting hole. The housing of the film-dispensing motor is connected to the outer flange. The power output shaft of the film-dispensing motor passes through the shaft mounting hole and is fitted with a sleeve. The sleeve and the power output shaft of the film-dispensing motor rotate synchronously through a key and keyway. One end of the film roll is supported in an inner flange by a drive-side bearing. The inner flange is fixed to the first column by bolts. One end of the film roll and the sleeve rotate synchronously through a key and keyway. The other end of the film roll is supported in an opening slot of the second column by a connecting seat bearing. A clamping block for clamping the connecting seat bearing is detachably connected in the opening slot. This technical solution allows for convenient and quick replacement of the plastic film. The connection is reliable.

[0008] Preferably, the suspension base is provided with a first column and a second column arranged opposite to each other. The film covering mechanism includes a film roll rotatably connected at both ends to the first and second column. The geotextile covering mechanism includes a geotextile storage box and two traction rollers. The two ends of the two traction rollers are rotatably connected to the first and second column. A first guide roller is provided at the upper end of the geotextile storage box. A second guide roller is provided between the first guide roller and the traction roller. The height of the first guide roller is greater than the height of the second guide roller. The traction roller is located above the film roll and is connected to a traction motor. In use, the geotextile passes sequentially around the upper side of the first guide roller and the lower side of the second guide roller and then passes between the two traction rollers. Due to the large thickness of the geotextile, the winding method on the shaft results in a large roll volume and weight, placing high demands on the shaft and occupying a large amount of space. This preferred method uses a storage box, where the geotextile is folded and placed, ensuring convenient unwinding and easy loading. This technical solution can tighten the geotextile, which is beneficial for flattening and laying.

[0009] Preferably, the watering mechanism includes a horizontal water distribution pipe connected to the suspension base, a water storage tank, and a water pump that delivers water from the water storage tank to the horizontal water distribution pipe. The horizontal water distribution pipe is equipped with several forward-spraying nozzles. In use, water is sprayed by driving the water pump.

[0010] Preferably, the cable laying mechanism includes several cable reel support frames distributed laterally. Each support frame includes a connecting block connected to the suspension base at one end, a horizontal shaft head connected to the connecting block at the other end, a blocking pin passing through the other end of the horizontal shaft head, and a guide ring connected to the connecting block. In use, the cable reel, formed by winding the cable, is placed on the horizontal shaft head. The connecting block and the blocking pin block both ends of the cable reel. During use, the outer end of the cable wound from the reel passes through the guide ring and is connected to the box girder. This allows for independent cable laying in each trench.

[0011] Preferably, the suspension base has two horizontally distributed columns, each with a vertical groove on its inner side. The two ends of the crossbar are slidably connected to these vertical grooves. The upper sections of the two columns are connected together by a crossbeam. The rake tooth lifting mechanism includes a vertical guide rod whose lower end is connected to the crossbar, a vertical lead screw whose lower end is threaded to the crossbar and passes through it, and a lifting motor that drives the lead screw to rotate. The upper end of the vertical guide rod passes through the crossbeam, and the lifting motor is fixed to the crossbeam. This design is compact and prevents the rake teeth from interfering with other operations when roughening is not required.

[0012] Preferably, the melting point of the plastic film is higher than the set temperature but lower than 100°C. After curing, the plastic film is melted by heating, making it easy to remove.

[0013] The beneficial effects of this invention are: geotextile covering for curing can be performed without curing, shortening the curing time; the plastic film has good tension; it reduces water consumption during curing; it saves energy during curing and insulation; removing the plastic film is convenient; it allows for one-time surface roughening and moisture retention curing of the box girder, shortening the curing process and improving efficiency; it provides reliable connection with the cast-in-place bridge deck; it allows for zoned curing; and it is convenient and energy-saving during insulation, as existing insulation is carried out inside insulation sheds, which have large control volumes and result in significant energy waste. Removing the plastic film is quick, thus shortening curing time; and it saves energy during top surface heating. Attached Figure Description

[0014] Figure 1 This is a rear view schematic diagram of the maintenance equipment of the present invention;

[0015] Figure 2 This is a side view schematic diagram of the box girder top surface curing device;

[0016] Figure 3 This is a front view schematic diagram of the box girder top surface curing device;

[0017] Figure 4 for Figure 3A magnified view of a portion of point B;

[0018] Figure 5 A schematic diagram of the relevant structures for roughening the top surface of a box girder using a curing device.

[0019] Figure 6 for Figure 5 A magnified view of a portion at point C;

[0020] Figure 7 This is a schematic diagram showing the connection between the film roll and the suspension base;

[0021] Figure 8 This is a schematic diagram illustrating the principle of geotextile unwinding in this invention;

[0022] Figure 9 for Figure 1 A magnified view of a portion at point D;

[0023] Figure 10 This is a side enlarged schematic diagram of the maintenance equipment of the present invention.

[0024] In the diagram: 1. Bottom formwork plate; 2. Curing chamber; 3. Longitudinal track; 4. Bottom formwork traveling wheel; 5. Box girder top surface curing device; 6. Suspension frame; 7. Suspension base frame; 8. Horizontal bar; 9. Rake teeth; 10. Pointed head; 11. Cutting edge; 48. Column; 12. Vertical chute; 13. Horizontal beam; 14. Vertical guide rod; 15. Vertical screw rod; 16. Lifting motor; 17. Swing arm; 18. Roller; 19. Film roll; 20. Film unloading motor; 21. First column head; 22. Second column head; 23. Outer flange; 24. Sleeve; 25. Active side bearing; 26. Inner flange; 27. Connecting seat bearing; 28. Pressing block; 29. ​​Film roller; 50. Geotextile storage box; 30. Traction roller; 31. 32. Guide roller 1, 33. Second guide roller 2, 34. Drive gear 3, 35. Driven gear 3, 36. Transverse water distribution pipe 3, 37. Water tank 3, 38. Water pump 3, 39. Water outlet 3, 40. Wire roll support frame 4, 41. Horizontal suspension rod 4, 42. Connecting block 4, 43. Horizontal shaft head 4, 44. Barrier pin 4, 45. Guide ring 4, 46. Wire roll 4, 47. Traction motor 4, 119. Film roll 119, Upper longitudinal shaft 49, Lower longitudinal shaft 50, Longitudinal water supply pipe 51, Upper sealing plate 52, Lower sealing plate 53, Spray head 54, Trench 112, Plastic film 113, Cable 114, Water 115, Geotextile 116, Water-blocking flange 117, Film roll 119, Box girder 120. Detailed Implementation

[0025] The present invention will now be further described with reference to the accompanying drawings and specific embodiments.

[0026] See Figures 1 to 10A method for curing precast box girders is disclosed, which is accomplished using curing equipment. The equipment includes a curing chamber 121, a box girder top surface curing device 6, and a longitudinal track 4 extending from the front end into the curing chamber. In use, the bottom formwork 1 is supported on the longitudinal track by bottom formwork wheels 5. The cast box girder 120 is positioned longitudinally on the bottom plate. The box girder top surface curing device is located at the entrance end of the curing chamber. The box girder top surface curing device includes a suspension base 8 suspended above the track by a suspension frame 7. The suspension base 8 is equipped with a crossbar 9, several rake teeth 10 connected to the crossbar and distributed laterally, with their lower ends extending downwards beyond the crossbar, and a rake tooth lifting mechanism that drives the crossbar to rise and fall, causing the rake teeth to extend downwards beyond the suspension base 8. The lower end of the rake teeth has a pointed tip 11, and the front side has a vertically extending cutting edge 48. The suspension base has two horizontally distributed columns 12, with vertical grooves 13 on the inner side of each column. The two ends of a crossbar are slidably connected to the grooves. The upper sections of the two columns are connected together by a crossbeam 14. The rake tooth lifting mechanism includes a vertical guide rod 15 connected to the crossbeam at its lower end, a vertical lead screw 16 threaded to the crossbeam at its lower end and passing through the crossbeam, and a lifting motor 17 that drives the lead screw to rotate. The upper end of the vertical guide rod passes through the crossbeam, and the upper end of the vertical lead screw is rotatably connected to the crossbeam. The lifting motor is fixed to the crossbeam. The suspension base also includes a film covering mechanism, a watering mechanism, a line laying mechanism, a geotextile covering mechanism located behind the crossbar, and a compaction roller 19 located in front of the suspension base and connected to it via a swing arm 18. The compaction roller extends laterally. The film covering mechanism includes a film roll 20 rotatably connected to the suspension base and a film unloading motor 21 that drives the film roll to rotate. The film roll and the suspension base are detachably configured. Specifically, the suspension base is provided with a first column 22 and a second column 23 arranged opposite to each other. The film roll is mounted between the first column and the second column. The film feeding motor is located outside the first column. The first column has a shaft mounting hole. An outer flange 24 is bolted to the outside of the shaft mounting hole. The housing of the film feeding motor is connected to the outer flange. The power output shaft of the film feeding motor passes through the shaft mounting hole and is fitted with a sleeve 25. The sleeve and the power output shaft of the film feeding motor rotate synchronously through a key and keyway. One end of the film roll is supported by an inner flange 27 through an active side bearing 26. The inner flange is also fixed to the first column by bolts. One end of the film roll and the sleeve also rotate synchronously through a key and keyway. The other end of the film roll is supported in the opening slot of the second column through a connecting seat bearing 28. A clamping block 29 for clamping the connecting seat bearing is detachably connected in the opening slot. Before assembling the film roll, the inner flange is integrally assembled with one end of the film roll, and the other end of the film roll is assembled with the connecting bearing. When assembling the film roll, one end of the film roll is inserted into the sleeve, and then the inner flange is bolted to the first mounting beam. At the same time, the connecting bearing on the other end of the film roll is inserted into the opening groove, and the bolted removable clamping block is pressed onto the second mounting beam to tighten the connecting bearing.When the film roll needs to be removed for replacement, first remove the removable clamping block and inner flange, then move the film roll axially to separate it from the sleeve, and then remove the film roll. Before installation, the film roll is wound with film 50. The geotextile covering mechanism includes a geotextile storage box 30 and two traction rollers 31. In use, the geotextile is pulled by the two traction rollers. The two ends of the two traction rollers are rotatably connected to the first column and the second column. The upper end of the geotextile storage box is provided with a first guide roller 32, and a second guide roller 33 is provided between the first guide roller and the traction roller. The height of the first guide roller is greater than the height of the second guide roller. The geotextile passes around the upper side of the first guide roller and the lower side of the second guide roller in sequence and then passes between the two traction rollers. The traction roller is located above the film roll. One end of one traction roller is connected to the traction motor 47, and the other end is provided with a drive gear 34. The drive gear meshes with the driven gear 35 connected to the other traction roller. The geotextile storage box has a rectangular structure, with the geotextile inside folded and aligned. The watering mechanism includes a transverse water distribution pipe 36 connected to the suspension base, a water storage tank 37, and a water pump 38 that transports water from the water storage tank to the transverse water distribution pipe. The transverse water distribution pipe is equipped with several forward-spraying nozzles 39. The cable laying mechanism includes several cable reel support frames 40, which are distributed transversely. Each cable reel support frame includes a connecting block 42 connected at one end to a transverse suspension rod 41 on the suspension base, a transverse shaft head 43 connected at one end to the connecting block, a blocking pin 44 passing through the other end of the transverse shaft head, and a guide ring 45 connected to the connecting block. In use, the cable reel 46 wound with cable is fitted onto the transverse shaft head, with the connecting block and blocking pin blocking both ends of the cable reel, and the cable end on the cable reel passing through the guide ring.

[0027] When using the box girder top surface curing device, the film roll 119 is installed on the film roll shaft, the water tank is filled with water, the geotextile is placed in the geotextile storage box, and the geotextile passes around the upper side of the first guide roller, the lower side of the second guide roller and between the two traction rollers in sequence. The cable roll with the same number of rake teeth is carried on the cable laying mechanism.

[0028] After the box girder is hinged and initially set outside the curing chamber, it is pushed into the curing chamber through the bottom template for curing. When the box girder passes under the suspended base frame, the rake tooth lifting mechanism drives the crossbar to descend until the rake teeth insert into the top surface of the box girder to a set depth. This fixes one end of the plastic film supported by the covering mechanism, one end of the geotextile supported by the geotextile covering mechanism, and one end of the cable roll supported by the cable laying mechanism at the front end along the length of the box girder. The cable is located above the plastic film, and the cable is aligned one-to-one with the rake teeth. The rolling roller presses on the cable and is located below the geotextile. The rake teeth form grooves on the box girder, and the plastic film is covered onto the box girder. The cable is pressed into the groove by the rolling roller through the plastic film. Water is sprayed onto the plastic film by the watering mechanism, and the geotextile covers the plastic film and the cable. The cable is an electric heating wire. During curing in the curing chamber, the cable is electrically heated to heat the water on the plastic film to maintain the set temperature. After curing is completed, remove the geotextile and then heat it to the set temperature until the plastic film melts.

[0029] The curing chamber has an upper longitudinal shaft 49 rotatably connected to each of its two transverse side walls, a lower longitudinal shaft 50 rotatably connected to each, and a longitudinal water supply pipe 51 fixedly connected to each. The upper longitudinal shaft has an upper sealing plate 52 extending longitudinally. Rotating the upper longitudinal shaft allows the upper sealing plate to seal against the upper end of the side surface of the box girder located in the curing chamber and disengage from the side surface of the box girder located in the curing chamber. The lower longitudinal shaft has a lower sealing plate 53 extending longitudinally. Rotating the lower longitudinal shaft allows the lower sealing plate to seal against the side surface of the bottom formwork located in the curing chamber and disengage from the side surface of the bottom formwork located in the curing chamber. During curing of the box girder in the curing chamber, when the box girder reaches its designated receiving position, the upper and lower sealing plates abut against adjacent side surfaces. The longitudinal water supply pipe is located between the upper and lower longitudinal shafts and has spray nozzles 54 distributed longitudinally for spraying water onto the side surface of the box girder located in the curing chamber. Water is sprayed onto the sides of the box girder through sprinkler heads for curing.

[0030] The box girder maintenance process includes: A) Top surface maintenance; B) Side surface maintenance. A includes: A1) Roughening: Forming several longitudinally extending grooves 112 on the partially set but not yet cured surface of the box girder, with the grooves parallel to each other; A2) Covering with film: Covering the upper surface of the box girder with plastic film 113; A3) Tensioning: Inserting several cables 114 through the plastic film into the grooves, with the cables extending along the direction of the grooves, and tensioning the plastic film during the insertion of the cables into the grooves; A4) Watering: Pouring water 115 onto the plastic film; A5) Covering with geotextile: Covering the box girder with geotextile 116 on top of the plastic film. A1 to A5 are completed when the box girder passes under the suspension base; water-retaining flanges 117 are provided on both sides of the upper surface of the box girder perpendicular to the extension direction of the trench, and the water in A4 submerges the part of the box girder located between the water-retaining flanges; A6, heat preservation: the cable is energized to heat the water on the plastic film and keep it constant at the set temperature; A7, removal of the covering layer: the geotextile is collected again for reuse, the water on the plastic film is evaporated, and the cable is energized until the temperature generated by the cable is higher than the melting point of the plastic film, thereby melting and burning the plastic film; B, as well as A6 and A7, are completed in the curing room.

Claims

1. A method for curing precast box girders, characterized in that, Includes A. Box girder top surface curing; B. Box girder side surface curing: spraying water on the two exposed sides of the box girder; A includes A1. Roughening: forming several longitudinally extending grooves on the surface of the box girder that has just set but not yet cured, with the grooves parallel to each other; A2. Covering: covering the upper surface of the box girder with a plastic film. A3. Tensioning: Insert several cables into the groove through the plastic film. The cables extend along the direction of the groove. Tension the plastic film during the process of inserting the cables into the groove. A4. Watering: Pour water onto the plastic film; A5. Covering with geotextile: Cover the box girder with geotextile over the plastic film; A6. Insulation: Heat the water on the plastic film by energizing the cable and maintain it at a set temperature; A7. Removing the covering layer: Collect the geotextile for reuse, allow the water on the plastic film to evaporate, and energize the cable until the temperature generated by the cable is higher than the melting point of the plastic film, thus melting and burning it; Water-retaining flanges are provided on both sides of the upper surface of the box girder perpendicular to the extension direction of the trench. The water in A4 submerges the part of the box girder located between the water-retaining flanges. Steps A and B are achieved through the curing chamber and the box girder top surface curing device. The box girder curing chamber is equipped with longitudinal guide rails for transporting the box girder into the curing chamber. The bottom formwork supporting the box girder is supported on the longitudinal guide rails by the bottom formwork traveling wheels. The box girder is located on the base plate in a longitudinally extending state. The curing chamber has an upper longitudinal shaft rotatably connected to each of its two transverse side walls, a lower longitudinal shaft rotatably connected to each, and a longitudinal water supply pipe fixedly connected to each. The upper longitudinal shaft has an upper sealing plate extending longitudinally, and the lower longitudinal shaft has a lower sealing plate extending longitudinally. The longitudinal water supply pipe is located between the upper and lower longitudinal shafts and has longitudinally distributed spray nozzles for spraying water onto the side surfaces of the box girder located in the curing chamber. The box girder top surface curing device includes a suspension base frame suspended above the track via a suspension frame. The suspension base frame has a crossbar, several transversely distributed rake teeth extending downwards beyond the crossbar and connected to the crossbar, and a drive mechanism for raising and lowering the crossbar. The rake teeth extend downwards beyond the suspension base frame via a rake tooth lifting mechanism. The suspension base frame also includes a film covering mechanism, a watering mechanism, a geotextile laying mechanism, and a geotextile covering mechanism located in front of the crossbar, as well as a laterally extending compaction roller connected to the suspension base frame via a swing arm. During maintenance, the plastic film is supported on the film covering mechanism, the geotextile on the geotextile covering mechanism, and the same number of cable rolls as the rake teeth are supported on the geotextile laying mechanism. When the box girder passes under the suspension base frame, the rake tooth lifting mechanism drives the crossbar to descend until the rake teeth insert into the top surface of the box girder to a set depth, fixing one end of the plastic film supported on the film covering mechanism, one end of the geotextile on the geotextile covering mechanism, and one end of the cable rolls on the geotextile laying mechanism to a point along the length of the box girder. At the end, the cables are distributed laterally, located above the plastic film, and aligned one-to-one with the rake teeth. The rolling roller presses on the cables and is located below the geotextile. The rake teeth form grooves on the box girder. The plastic film is covered onto the box girder, and the cables are pressed into the grooves by the rolling roller through the plastic film. Water is sprayed onto the plastic film by the watering mechanism, and the geotextile covers the plastic film and the cables, thus completing steps A1 to A5. After the box girder enters the curing chamber, the upper longitudinal shaft is rotated so that the upper sealing plate seals against the upper end of the side surface of the box girder. The lower longitudinal shaft is rotated so that the lower sealing plate seals against the side surface of the bottom template. Water is sprayed onto the side of the box girder through the spray head, thus achieving step B. Steps A6 and A7 are carried out in the curing chamber. The cables are electric heating wires.

2. The method for curing precast box girders according to claim 1, characterized in that, The film covering mechanism includes a film roll rotatably connected to a suspension base and a film unloading motor that drives the film roll to rotate. The film roll is detachably connected to the suspension base.

3. The method for curing precast box girders according to claim 2, characterized in that, The suspension base is equipped with a first column and a second column arranged opposite to each other. The film roll is located between the first column and the second column. The film-laying motor is located outside the first column. The first column has a shaft mounting hole. An outer flange is bolted to the outside of the shaft mounting hole. The housing of the film-laying motor is connected to the outer flange. The power output shaft of the film-laying motor passes through the shaft mounting hole and is fitted with a sleeve. The sleeve and the power output shaft of the film-laying motor rotate synchronously through a key and keyway. One end of the film roll is supported in the inner flange by the active side bearing. The inner flange is fixed to the first column by bolts. One end of the film roll and the sleeve rotate synchronously through a key and keyway. The other end of the film roll is supported in the opening slot of the second column by the connecting seat bearing. A clamping block for clamping the connecting seat bearing is detachably connected in the opening slot.

4. The method for curing precast box girders according to claim 1, characterized in that, The suspension base is provided with a first column and a second column arranged opposite to each other. The film covering mechanism includes a film roll that is rotatably connected to the first column and the second column at both ends. The geotextile covering mechanism includes a geotextile storage box and two traction rollers. The two ends of the two traction rollers are rotatably connected to the first column and the second column. A first guide roller is provided at the upper end of the geotextile storage box. A second guide roller is provided between the first guide roller and the traction roller. The height of the first guide roller is greater than the height of the second guide roller. The traction roller is located above the film roll and is connected to a traction motor. In use, the geotextile passes around the upper side of the first guide roller and the lower side of the second guide roller in sequence and then passes between the two traction rollers.

5. A method for curing precast box girders according to claim 1, 2, 3, or 4, characterized in that, The watering mechanism includes a horizontal water distribution pipe connected to the suspension base, a water storage tank, and a water pump that transports water from the water storage tank to the horizontal water distribution pipe. The horizontal water distribution pipe is equipped with several water nozzles that spray forward.

6. A method for curing precast box girders according to claim 1, 2, 3, or 4, characterized in that, The cable laying mechanism includes several cable reel support frames distributed laterally. Each cable reel support frame includes a connecting block connected to the suspension base at one end, a horizontal shaft head connected to the connecting block at one end, a blocking pin passing through the other end of the horizontal shaft head, and a guide ring connected to the connecting block. In use, the cable reel, formed by winding a cable, is sleeved on the horizontal shaft head. The connecting block and the blocking pin block both ends of the cable reel. In use, the outer end of the cable wound out of the cable reel passes through the guide ring and is connected to the box girder.

7. A method for curing precast box girders according to claim 1, 2, 3, or 4, characterized in that, The suspension base is provided with two horizontally distributed columns. The inner side of each column is provided with a vertical sliding groove. The two ends of the crossbar are slidably connected in the vertical sliding groove. The upper sections of the two columns are connected together by a crossbeam. The rake tooth lifting mechanism includes a vertical guide rod whose lower end is connected to the crossbar, a vertical screw rod whose lower end is threaded to the crossbar and passes through the crossbar, and a lifting motor that drives the screw rod to rotate. The upper end of the vertical guide rod passes through the crossbeam, and the lifting motor is fixed together with the crossbeam.

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