A cast-in-place caisson bottom water stop belt pre-compression device and construction method

Abstract

The present application relates to the technical field of building construction, and particularly relates to a pre-compression device for a bottom water stop belt of a cast-in-situ caisson gate and a construction method, wherein the water stop belt is pre-compressed and deformed before cast-in-situ construction of the caisson gate, then fine sand leveling layer is laid, cast-in-situ construction of the caisson gate is carried out on the upper part of the leveling layer, finally the pre-compression device is removed and the reserved holes are blocked, and the bottom water stop of the caisson gate is completed. Compared with the construction method of first casting the caisson and then lifting and falling, the installation precision and quality of the omega-shaped water stop belt are high, the bottom water stop effect of the cast-in-situ caisson gate is more guaranteed, the construction operation is simple, the construction period is short, and the cost investment is low.

Description

Technical Field

[0001] This invention relates to the field of building construction technology, and in particular to a pre-compression device and construction method for the bottom waterstop of a cast-in-place dock gate caisson. Background Technology

[0002] The dock gate caisson serves as the entrance to the dry dock chamber. To ensure the water-stopping function at the bottom of the caisson, two Ω120 type waterstops need to be installed. When the waterstops are compressed under the weight of the caisson, they achieve a seal between themselves and the bottom plate of the caisson. Since the dry dock chamber structure is entirely constructed using in-situ cast-in-place technology, effective methods must be employed to ensure the Ω120 type waterstops deform to the design deformation value before the cast-in-place caisson is constructed. The current method is as follows: First, the caisson is cast in place. Then, a large-scale combined hydraulic jacking system is used to lift the caisson in place. Personnel enter the bottom of the caisson to install and reinforce the two Ω120 type waterstops. Finally, the caisson is lowered back into place using the same system, allowing the two Ω120 type waterstops at the bottom to be compressed and effectively stop the water flow. The problems are: the in-situ jacking of the dock gate caisson requires the concrete to reach 100% of the design strength and takes at least 28 days, extending the construction period by 1 month; the large-scale combined hydraulic jacking system is complex and expensive, requiring professional manufacturers to carry out the construction; at the same time, the construction efficiency of manually entering the bottom of the dock gate caisson to install and reinforce two Ω120 type waterstops is low and the safety risks to personnel are high. Summary of the Invention

[0003] The purpose of this invention is to solve the technical problem that the Ω-shaped waterstop at the bottom of the cast-in-place caisson cannot withstand pressure to stop water. It provides a pre-compression device for the bottom waterstop of the cast-in-place dock gate caisson. By using this pre-compression device, the bottom waterstop is compressed and deformed before the cast-in-place dock gate caisson is cast. Then the cast-in-place dock gate caisson is cast. Finally, the pre-compression device is removed and the bottom of the dock gate caisson is sealed and waterstopped.

[0004] Another objective of this invention is to provide a construction method for the pre-compression device of the bottom waterstop of the above-mentioned cast-in-place dock gate caisson.

[0005] The technical solution adopted by the present invention to achieve the above objectives is: a method for pre-compression construction of the bottom waterstop of a cast-in-place dock gate caisson, comprising the following steps: S1. Preparatory work before the installation of the pre-compression device, including the construction of embedded steel brackets, precision-rolled threaded steel bar sleeves and matching positioning bolts, and foundation concrete slab construction. The specific construction steps are as follows: S11. Lay out the position of the Ω-shaped waterstop on the reinforcement of the foundation concrete slab under the caisson of the dock gate, and symmetrically arrange the welded embedded steel brackets on both sides of the Ω-shaped waterstop. S12. Install double-row precision threaded steel bar sleeves and matching positioning bolts. The position of the precision threaded steel bar embedded sleeves should avoid the dock gate caisson wall to ensure that the double-row precision threaded steel bars are aligned in the dock gate caisson compartment. S13. When pouring the foundation concrete slab, the top elevation of the pre-embedded sleeve of the fine-rolled threaded steel bar should be consistent with the surface elevation of the foundation concrete slab.

[0006] S2. Installation of the pre-compression device, including the installation of Ω-shaped waterstops, H-beams and bottom sealing steel plates, precision-rolled threaded steel bars, and channel steel beams. The specific construction steps are as follows: S21. Install an Ω-shaped waterstop on the top surface of the foundation concrete slab and fix the Ω-shaped waterstop with the matching positioning bolts. S22. Install and weld H-beams and bottom sealing steel plates longitudinally on the upper part of the Ω-shaped waterstop, and use temporary supports on both sides of the H-beams simultaneously. S23. Install fine-rolled threaded steel bars sequentially from one end of the Ω-shaped waterstop. Screw the double rows of fine-rolled threaded steel bars downward into the pre-embedded sleeves of the foundation concrete slab. Use PVC protective sleeves for the fine-rolled threaded steel bars located within the cast-in-place dock gate caisson bottom slab area to facilitate the removal of the fine-rolled threaded steel bars later. S24. Install and weld the transverse channel steel beam on the upper part of the H-beam, and pass through the transverse channel steel beam with double-row precision rolled threaded steel, and tighten the double-row precision rolled threaded steel high-strength nuts on the upper part of the transverse channel steel beam. S25. Remove the temporary supports on both sides of the H-beam and complete the initial installation and positioning of the pre-compression device.

[0007] The pre-compression construction of S3 and Ω-shaped waterstops includes placing jacks, installing reaction channel steel beams, supporting the jacks upwards, and retracting the jacks. The specific construction steps are as follows: S31. A jack is placed on the upper part of the transverse channel steel beam of the pre-compression device, and a reaction channel steel beam is installed on the upper part of the jack. The reaction channel steel beam is tightened to the precision rolled threaded steel bar with a high-strength nut. S32. The jack is used to support the reaction channel steel beam upward. Under the action of the reaction force, the transverse channel steel beam and H-beam jointly squeeze the Ω-shaped waterstop downward. The Ω-shaped waterstop is slowly deformed under pressure. S33. Tighten the two rows of high-strength nuts on the upper part of the transverse channel steel beam again. The double-sided precision-rolled threaded steel bars bear the force at the same time. After monitoring the deformation of the Ω-shaped waterstop and ensuring that it reaches the design requirements, the jack is finally used to unload and recover the force. S34. Repeat steps S31 to S33 to tighten all transverse channel steel beams and precision rolled threaded steel bars from one end of the waterstop. S35. The prefabricated device bears the overall force, and the overall compression deformation of the Ω-shaped waterstop reaches the design requirements, completing the pre-compression of the Ω-shaped waterstop; continuously observe the compression deformation, and if local deformation rebound occurs, use jacks for secondary correction and tightening.

[0008] S4. Construction of the fine sand leveling layer, including cleaning the foundation concrete slab, spreading the fine sand leveling layer, and laying plywood. The specific construction steps are as follows: After the S41 and Ω-type waterstops pass the compression deformation test, clean the surface of the foundation concrete slab of the dock gate caisson and ensure that no other debris is present. S42. A fine sand leveling layer is manually spread on the upper part of the foundation concrete slab. The thickness of the fine sand should be 1cm below the top surface of the net height h2 of the compressed Ω-shaped waterstop. S43. Manually level the fine sand leveling layer, and at the same time, sprinkle a small amount of water to compact it; S44. Lay a 1cm thick layer of plywood on the leveling layer surface, with the plywood at the same height as the upper surface of the compressed Ω-shaped waterstop. S45. The plywood boards are securely fixed together manually, and a layer of kraft paper is laid on the surface of the plywood boards to complete the fine sand leveling layer construction.

[0009] S5. Removal of the pre-compression device and sealing of the holes: The specific construction steps are as follows: S51. After the construction of the cast-in-place dock gate caisson is completed, the pre-compression device has been fully embedded in the thickness h1 of the bottom plate of the dock gate caisson. Manual personnel enter the bottom of the dock gate caisson compartment and remove the double-row high-strength nuts of the high-strength threaded steel bars on the upper part of the transverse channel steel beam to unload all the high-strength threaded steel bars. S52. Remove the fine-rolled threaded steel bars one by one from the pre-embedded sleeves in the foundation concrete, and then lift the removed fine-rolled threaded steel bars and high-strength nuts out of the dock gate caisson; S53. Insert expansion bolts into the reserved holes of the PVC protective sleeves for the removed fine-rolled threaded steel bars, and fill them with polyurethane foam for water-stopping treatment.

[0010] During the construction of the cast-in-place dock gate caisson, the pre-compression device was monitored throughout the process. A displacement monitoring red line was set and deformation records were continuously kept to avoid affecting the compression index of the Ω-shaped waterstop due to concrete vibration.

[0011] After the water test, the cast-in-place dock gate caisson was first floated out of the dock, then divers removed the plywood and fine sand leveling layer underwater, and finally the dock gate caisson was floated back to its position and officially put into use.

[0012] A pre-compression device for the bottom waterstop of a cast-in-place dock gate caisson includes sleeves, a bottom sealing steel plate, H-beams, channel steel beams, precision-rolled threaded steel bars, high-strength nuts, and jacks. Double rows of sleeves are symmetrically embedded in the bottom foundation concrete slab of the Ω-shaped waterstop. The bottom sealing steel plate is installed at the center above the Ω-shaped waterstop. The H-beams are longitudinally welded to the center above the bottom sealing steel plate. The lower channel steel beams are transversely welded above the H-beams, with the spacing between the channel steel beams matching the pre-embedded spacing of the double rows of sleeves. The jacks are installed directly above the lower channel steel beams. The upper channel steel beams are installed directly above the jacks. Precision-rolled threaded steel bars are symmetrically inserted into the upper and lower channel steel beams and screwed downwards into the double rows of sleeves. High-strength nuts are screwed onto the precision-rolled threaded steel bars and secured above the upper and lower channel steel beams respectively.

[0013] This invention first employs a pre-compression device to pre-compress and deform the Ω-shaped waterstop at the bottom of the dock gate caisson to the design value. Then, a fine sand leveling layer is laid beneath the pre-compression device to protect the Ω-shaped waterstop. Next, the dock gate caisson is cast in situ. Finally, the precision-rolled threaded steel bars of the pre-compression device are removed, and the reserved holes are sealed. The Ω-shaped waterstop achieves the designed compression and water-stopping effect. By applying the above-mentioned pre-compression device construction process, the difficulty of construction operations and safety risks are reduced, effectively saving construction time and cost, and ensuring the installation accuracy and water-stopping quality of the Ω-shaped waterstop. This invention's method provides high installation accuracy and quality of the Ω-shaped waterstop, ensures a more reliable water-stopping effect at the bottom of the cast-in-place dock gate caisson, and features simple construction operations, a short construction period, and low cost. Attached Figure Description

[0014] Figure 1 This is a cross-sectional schematic diagram of the pre-compression device for the waterstop of the present invention.

[0015] Figure 2 This is a longitudinal section schematic diagram of the pre-compression device for the waterstop of the present invention.

[0016] Figure 3 This is a schematic diagram of the compression deformation of the Ω-shaped waterstop of the present invention.

[0017] In the diagram: 1-Precision rolled threaded steel bar, 2-High-strength nut, 3-Jack, 4-Channel steel beam, 5-H-beam, 6-Dock gate caisson, 7-Bottom sealing steel plate, 8-Fine sand leveling layer, 9-Ω-type waterstop, 10-Foundation concrete slab, 11-Sleeve, 12-PVC protective sleeve, 13-Plywood, 14-Positioning bolt. Detailed Implementation

[0018] The present invention will be further described below with reference to the accompanying drawings, but the present invention is not limited to the specific embodiments.

[0019] Example 1

[0020] like Figure 1 , Figure 2 As shown, a pre-compression device for the bottom waterstop of a cast-in-place dock gate caisson is disclosed. The pre-compression device includes sleeves 11, a bottom sealing steel plate 7, H-beams 5, channel steel beams 4, precision-rolled threaded steel bars 1, high-strength nuts 2, and jacks 3. The double-row sleeves 11 are symmetrically embedded in the foundation concrete slab 10 at the bottom of the Ω-shaped waterstop 9. The bottom sealing steel plate 7 is installed at the center above the Ω-shaped waterstop 9, and the H-beams 5 are longitudinally welded to the center above the bottom sealing steel plate 7. The lower layer... The channel steel beam 4 is horizontally welded above the H-beam 5, and the spacing of the channel steel beam 4 is consistent with the pre-embedded spacing of the double-row sleeve 11; the jack 3 is installed directly above the lower channel steel beam 4; the upper channel steel beam 4 is installed directly above the jack 3; the finely rolled threaded steel bar 1 is symmetrically inserted into the upper and lower channel steel beams 4 and screwed downward into the double-row sleeve 11; the high-strength nut 2 is screwed onto the finely rolled threaded steel bar 1 and tightened above the upper and lower channel steel beams 4 respectively.

[0021] All the above profiles are made of materials no less than Q345. The bottom sealing steel plate 7 is 20mm thick. The H-beam 5 is H400 double-jointed. The channel steel beam 4 is No. 10 channel steel double-jointed. The precision rolled threaded steel bar 1 is 25mm in diameter. The spacing L of the precision rolled threaded steel bar 1 is controlled to be no more than 500mm. The jack 3 is a 50t hydraulic jack. The sleeve 11 and the high-strength nut 2 are both of the same model as the precision rolled threaded steel bar 1.

[0022] Example 2

[0023] The pre-compression construction method for the bottom waterstop of the cast-in-place dock gate caisson using the waterstop pre-compression device described in Example 1 involves pre-compressing the Ω-shaped waterstop 9 at the bottom of the dock gate caisson to a deformation of 3cm using the pre-compression device, then laying a fine sand leveling layer 8 on the bottom of the pre-compression device, followed by the cast-in-place construction of the dock gate caisson 6, and finally removing the pre-compression device and sealing the reserved holes to achieve the waterstop effect required by the design.

[0024] A method for pre-compressing the bottom waterstop of a cast-in-place dock gate caisson includes the following steps: S1. Preparatory work before the installation of the pre-compression device, including the construction of embedded steel brackets, precision-rolled threaded steel bar sleeves and matching positioning bolts, and foundation concrete slab construction. The specific construction steps are as follows: S11. Lay out the position of the Ω-shaped waterstop 9 on the steel reinforcement of the foundation concrete slab 10 under the caisson 6 of the dock gate, and symmetrically arrange and weld the embedded steel brackets on both sides of the Ω-shaped waterstop 9. S12. Install double-row fine-rolled threaded steel bar sleeve 11 and matching positioning bolt 14. The position of the fine-rolled threaded steel bar 1 embedded sleeve 11 should avoid the wall of the dock gate caisson 6 to ensure that the double-row fine-rolled threaded steel bar 1 is aligned with the dock gate caisson 6 compartment. S13. Pour the foundation concrete slab 10. The top elevation of the pre-embedded sleeve 11 of the fine-rolled threaded steel bar 1 is consistent with the surface elevation of the foundation concrete slab 10.

[0025] S2. Installation of the pre-compression device, including the installation of Ω-shaped waterstops, H-beams and bottom sealing steel plates, precision-rolled threaded steel bars, and channel steel beams. The specific construction steps are as follows: S21. Install an Ω-shaped waterstop 9 on the top surface of the foundation concrete slab 10 and fix the Ω-shaped waterstop 9 with the matching positioning bolts 14. S22. Install and weld H-beam 5 and bottom sealing steel plate 7 longitudinally on the upper part of Ω-shaped waterstop 9, and use temporary supports on both sides of H-beam 5 at the same time. S23. Install the fine-rolled threaded steel bars 1 sequentially from one end of the Ω-shaped waterstop 9. Screw the double-row fine-rolled threaded steel bars 1 downward into the pre-embedded sleeve 11 of the foundation concrete slab 10. Use PVC protective sleeves 12 for the fine-rolled threaded steel bars 1 within the bottom plate range of the cast-in-place dock gate caisson 6 to facilitate the removal of the fine-rolled threaded steel bars 1 later. S24. Install and weld the transverse channel steel beam 4 on the upper part of the H-beam 5, and pass the double-row fine-rolled threaded steel bar 1 through the transverse channel steel beam 4, and tighten the double-row fine-rolled threaded steel bar high-strength nut 2 on the upper part of the transverse channel steel beam 4. S25. Remove the temporary supports on both sides of H-beam 5 and complete the initial installation and positioning of the pre-compression device.

[0026] The pre-compression construction of S3 and Ω-shaped waterstops includes placing jacks, installing reaction channel steel beams, supporting the jacks upwards, and retracting the jacks. The specific construction steps are as follows: S31. A jack 3 is placed on the upper part of the transverse channel steel beam 4 of the pre-compression device, and a reaction channel steel beam 4 is installed on the upper part of the jack 3. The reaction channel steel beam 4 is tightened to the fine-rolled threaded steel bar 1 by a high-strength nut 2. S32. Operate the jack 3 to support the reaction channel steel beam 4 upward. Under the action of the reaction force, the transverse channel steel beam 4 and the H-beam 3 together compress the Ω-shaped waterstop 9 downward. The Ω-shaped waterstop 9 is slowly deformed under pressure. S33. Tighten the two rows of high-strength nuts 2 on the upper part of the transverse channel steel beam 4 again, and the double-sided precision rolled threaded steel bars 1 simultaneously bear the force. After monitoring the deformation of the Ω-shaped waterstop 9 and ensuring that it reaches the design requirements, the jack 3 finally unloads and recovers the force. S34. Repeat steps S31 to S33 to tighten all transverse channel steel beams 4 and fine-rolled threaded steel bars 1 from one end of the waterstop. S35. The prefabricated device bears the overall force, and the Ω-shaped waterstop 9 is compressed and deformed to meet the design requirements, thus completing the pre-compression of the Ω-shaped waterstop 9. The compression deformation is continuously monitored. If local deformation rebound occurs, a jack is used for secondary correction and tightening.

[0027] S4. Construction of the fine sand leveling layer, including cleaning the foundation concrete slab, spreading the fine sand leveling layer, and laying plywood. The specific construction steps are as follows: After the S41 and Ω-type waterstop 9 pass the compression deformation test, clean the surface of the foundation concrete slab 10 of the dock gate caisson 6, and no other debris shall appear. S42. A fine sand leveling layer 8 is manually spread on the top of the foundation concrete slab 10. The thickness of the fine sand should be 1cm below the top surface of the net height h2 of the compressed Ω-shaped waterstop 9. S43. Manually level the fine sand leveling layer 8, and at the same time, sprinkle a small amount of water to compact it; S44. Lay a 1cm thick layer of plywood 13 on the leveling layer surface. The plywood 13 is at the same height as the upper surface of the compressed Ω-shaped waterstop 9. S45. The plywood 13 is fixed securely by hand, and a layer of kraft paper is laid on the surface of the plywood 13 to complete the construction of the fine sand leveling layer 8.

[0028] S5. Removal of the pre-compression device and sealing of the holes: The specific construction steps are as follows: S51. After the construction of the cast-in-place dock gate caisson 6 is completed, the pre-compression device has been fully embedded in the thickness h1 of the bottom plate of the dock gate caisson 6. Manual personnel enter the bottom of the dock gate caisson 6 compartment and remove the double-row high-strength nuts 2 of the high-strength threaded steel bars 4 on the upper part of the transverse channel steel beam 4, so that all the high-strength threaded steel bars 1 are unloaded. S52. Remove each fine-rolled threaded steel bar 1 from the pre-embedded sleeve 11 in the foundation concrete by screwing it off. Then lift the removed fine-rolled threaded steel bar 1 and high-strength nut 2 out of the dock gate caisson 6. S53. Insert expansion bolts into the pre-reserved holes of the PVC protective sleeve 12 of the removed fine-rolled threaded steel bars, and fill them with polyurethane foam for water-stopping treatment.

[0029] During the construction of the cast-in-place dock gate caisson, the pre-compression device was monitored throughout the process. A displacement monitoring red line was set and deformation records were continuously kept to avoid affecting the compression index of the Ω-shaped waterstop due to concrete vibration.

[0030] After the water test, the cast-in-place dock gate caisson 6 of the present invention is first floated out of the dock, then the divers remove the plywood 13 and the fine sand leveling layer 8 underwater, and finally the dock gate caisson 6 is floated back to its position and put into formal use.

[0031] The pre-compression construction process of this invention can reduce the difficulty of construction operations and safety risks, effectively save construction time and cost input, and ensure the installation accuracy and water-stopping quality of the Ω-shaped waterstop.

[0032] The present invention has been described above with reference to the accompanying drawings. Of course, the specific implementation of the present invention is not limited to the above-described manner. Any improvements made using the inventive concept and technical solution of the present invention, or direct application to other situations without modification, are all within the protection scope of the present invention.

Claims

1. A method for pre-compressing the bottom waterstop of a cast-in-place dock gate caisson, characterized in that: Includes the following steps: S1. Preparatory construction before the installation of the pre-compression device, including the construction of embedded steel brackets, fine-rolled threaded steel bar sleeves and matching positioning bolts, and foundation concrete slabs. S2. Installation of pre-compression device, including Ω-shaped waterstop, H-beam and bottom sealing steel plate, fine rolled threaded steel bar, and channel steel beam; S3 and Ω-shaped waterstop pre-compression construction includes placing jacks, installing reaction channel steel beams, jacks supporting upwards, and jacks retraction; S4. Construction of fine sand leveling layer, including cleaning the foundation concrete slab, spreading fine sand leveling layer, and laying plywood. S5. Removal and sealing of the pre-compression device hole.

2. The pre-compression construction method for the bottom waterstop of a cast-in-place dock gate caisson according to claim 1, characterized in that: The specific construction steps for S1 are as follows: S11. Lay out the position of the Ω-shaped waterstop on the reinforcement of the foundation concrete slab under the caisson of the dock gate, and symmetrically arrange the welded embedded steel brackets on both sides of the Ω-shaped waterstop. S12. Install double-row precision threaded steel bar sleeves and matching positioning bolts. The position of the precision threaded steel bar embedded sleeves should avoid the dock gate caisson wall to ensure that the double-row precision threaded steel bars are aligned in the dock gate caisson compartment. S13. When pouring the foundation concrete slab, the top elevation of the pre-embedded sleeve of the fine-rolled threaded steel bar should be consistent with the surface elevation of the foundation concrete slab.

3. The pre-compression construction method for the bottom waterstop of a cast-in-place dock gate caisson according to claim 1, characterized in that: The specific construction steps for S2 are as follows: S21. Install an Ω-shaped waterstop on the top surface of the foundation concrete slab and fix the Ω-shaped waterstop with the matching positioning bolts. S22. Install and weld H-beams and bottom sealing steel plates longitudinally on the upper part of the Ω-shaped waterstop, and use temporary supports on both sides of the H-beams simultaneously. S23. Install fine-rolled threaded steel bars sequentially from one end of the Ω-shaped waterstop. Screw the double rows of fine-rolled threaded steel bars downward into the pre-embedded sleeves of the foundation concrete slab. Use PVC protective sleeves for the fine-rolled threaded steel bars located within the cast-in-place dock gate caisson bottom slab area to facilitate the removal of the fine-rolled threaded steel bars later. S24. Install and weld the transverse channel steel beam on the upper part of the H-beam, and pass through the transverse channel steel beam with double-row precision rolled threaded steel, and tighten the double-row precision rolled threaded steel high-strength nuts on the upper part of the transverse channel steel beam. S25. Remove the temporary supports on both sides of the H-beam and complete the initial installation and positioning of the pre-compression device.

4. The pre-compression construction method for the bottom waterstop of a cast-in-place dock gate caisson according to claim 1, characterized in that: The specific construction steps for S3 are as follows: S31. A jack is placed on the upper part of the transverse channel steel beam of the pre-compression device, and a reaction channel steel beam is installed on the upper part of the jack. The reaction channel steel beam is tightened to the precision rolled threaded steel bar with a high-strength nut. S32. The jack is used to support the reaction channel steel beam upward. Under the action of the reaction force, the transverse channel steel beam and H-beam jointly squeeze the Ω-shaped waterstop downward. The Ω-shaped waterstop is slowly deformed under pressure. S33. Tighten the two rows of high-strength nuts on the upper part of the transverse channel steel beam again. The double-sided precision-rolled threaded steel bars bear the force at the same time. After monitoring the deformation of the Ω-shaped waterstop and ensuring that it reaches the design requirements, the jack is finally used to unload and recover the force. S34. Repeat steps S31 to S33 to tighten all transverse channel steel beams and precision rolled threaded steel bars from one end of the waterstop. S35. The prefabricated device bears the overall force, and the Ω-shaped waterstop is compressed and deformed to meet the design requirements, thus completing the pre-compression of the Ω-shaped waterstop. Continuously monitor the deformation under pressure. If local deformation rebounds, use jacks for secondary correction and tightening.

5. The pre-compression construction method for the bottom waterstop of a cast-in-place dock gate caisson according to claim 1, characterized in that: The specific construction steps for S4 are as follows: After the S41 and Ω-type waterstops pass the compression deformation test, clean the surface of the foundation concrete slab of the dock gate caisson and ensure that no other debris is present. S42. A fine sand leveling layer is manually spread on the upper part of the foundation concrete slab. The thickness of the fine sand should be 1cm below the top surface of the net height h2 of the compressed Ω-shaped waterstop. S43. Manually level the fine sand leveling layer, and at the same time, sprinkle a small amount of water to compact it; S44. Lay a 1cm thick layer of plywood on the leveling layer surface, with the plywood at the same height as the upper surface of the compressed Ω-shaped waterstop. S45. The plywood boards are securely fixed together manually, and a layer of kraft paper is laid on the surface of the plywood boards to complete the fine sand leveling layer construction.

6. The pre-compression construction method for the bottom waterstop of a cast-in-place dock gate caisson according to claim 1, characterized in that: The specific construction steps for S5 are as follows: S51. After the construction of the cast-in-place dock gate caisson is completed, the pre-compression device has been fully embedded in the thickness h1 of the bottom plate of the dock gate caisson. Manual personnel enter the bottom of the dock gate caisson compartment and remove the double-row high-strength nuts of the high-strength threaded steel bars on the upper part of the transverse channel steel beam to unload all the high-strength threaded steel bars. S52. Remove the fine-rolled threaded steel bars one by one from the pre-embedded sleeves in the foundation concrete, and then lift the removed fine-rolled threaded steel bars and high-strength nuts out of the dock gate caisson; S53. Insert expansion bolts into the reserved holes of the PVC protective sleeves for the removed fine-rolled threaded steel bars, and fill them with polyurethane foam for water-stopping treatment.

7. The pre-compression construction method for the bottom waterstop of a cast-in-place dock gate caisson according to claim 1, characterized in that: During the construction of the cast-in-place dock gate caisson, the pre-compression device was monitored throughout the process. A displacement monitoring red line was set and deformation records were continuously kept to avoid affecting the compression index of the Ω-shaped waterstop due to concrete vibration.

8. The pre-compression construction method for the bottom waterstop of a cast-in-place dock gate caisson according to claim 1, characterized in that: After the water test, the cast-in-place dock gate caisson was first floated out of the dock, then divers removed the plywood and fine sand leveling layer underwater, and finally the dock gate caisson was floated back to its position and officially put into use.

9. A pre-compression device for the bottom waterstop of a cast-in-place dock gate caisson, characterized in that: The pre-compression device includes sleeves, bottom sealing steel plates, H-beams, channel steel beams, precision rolled threaded steel bars, high-strength nuts, and jacks; wherein the double rows of sleeves are symmetrically embedded in the foundation concrete slab at the bottom of the Ω-shaped waterstop. The bottom sealing steel plate is installed in the center above the Ω-shaped waterstop. The H-beam is longitudinally welded in the center above the bottom sealing steel plate. The lower channel steel beam is transversely welded above the H-beam. The spacing of the channel steel beam is consistent with the pre-embedded spacing of the double-row sleeve. The jack is installed directly above the lower channel steel beam; the upper channel steel beam is installed directly above the jack; the finely rolled threaded steel bars are symmetrically inserted into the upper and lower channel steel beams and screwed downwards into the double-row sleeves; the high-strength nuts are screwed onto the finely rolled threaded steel bars and secured above the upper and lower channel steel beams respectively.

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