Construction method of outer cofferdam and inner open caisson type water taking and draining head facility

Abstract

The invention provides a construction method of an outer cofferdam and inner open caisson type water taking and draining head facility, which is characterized by comprising the following steps of: 1, leveling a water bottom mud surface; (2) the steel cofferdam is immersed in the leveling position to sit on the beach; 3, the interior and the outer side of the steel cofferdam are filled; 4, the first section of the open caisson is poured in the stacking body in the steel cofferdam; 5, the open caisson is poured section by section, excavated and sunk; 6, after the open caisson sinks in place, a bottom sealing structure in the open caisson is poured; 7, a connecting beam between the steel cofferdam and the open caisson is poured, then a stacking body in the steel cofferdam is excavated, and bottom sealing concrete is poured; 8, water is pumped into the steel cofferdam, and pouring of the water taking and draining head structure is completed upwards; and 9, a water taking and draining pipeline is constructed, and connection of the water taking and draining pipeline and the open caisson is completed.

Description

Technical Field

[0001] This invention relates to the field of water intake and drainage engineering technology, and in particular to a construction method for a caisson-type water intake and drainage head facility within an outer perimeter weir. Background Technology

[0002] Currently, municipal water plants, power plants (including nuclear power plants), and related projects require large amounts of water intake and drainage to meet the cooling needs of generator units. The water intake and drainage head structure is the core of water intake and drainage engineering. Conventional water intake and drainage heads generally adopt two forms: multi-point water intake and drainage and single-point water intake and drainage.

[0003] Conventional construction methods include jacking risers within the water intake and drainage tunnel. However, due to limited space within the tunnel, the water intake cross-section of a single jacking riser is restricted, necessitating the installation of multiple consecutive jacking risers to ensure sufficient water intake. Furthermore, the jacking reaction force within the tunnel is limited, and as the tunnel depth increases, the jacking risers often struggle to penetrate the upper soil layers. Therefore, this method suffers from limitations such as the inability to allow for excessively deep water intake and drainage tunnels, and the excessive area occupied by multiple water intake points.

[0004] The characteristic of single-point water intake and drainage is that the single water intake cross-section is large. Conventional construction methods require first setting up a full-section foundation pit or caisson (including thin-walled steel cylinders) above water, and then excavating the entire structure inside. In aquatic environments, the bottom area of ​​the foundation pit or caisson is large, and the water pressure inside and outside the pit is high. Even if a large volume of soil is used to reinforce and seal the bottom of the foundation pit, and dewatering is carried out, the construction risk is still greater than that of a land-based foundation pit. Summary of the Invention

[0005] In order to solve the above problems, the present invention aims to provide a construction method for a caisson-type intake and drainage head facility within an outer perimeter weir.

[0006] This invention provides a construction method for a caisson-type intake and drainage head facility within an outer perimeter weir, characterized by comprising:

[0007] Step 1: Level the muddy surface at the bottom of the water;

[0008] Step 2: Place the steel cofferdam on the leveled area and let it sit on the beach;

[0009] Step 3: Fill the inside and outside of the steel cofferdam separately;

[0010] Step 4: The first section of the caisson is poured in the backfill inside the steel cofferdam;

[0011] Step 5: Construct the caisson section by section and excavate to sink it;

[0012] Step 6: After the caisson has sunk into place, pour the bottom sealing structure inside the caisson;

[0013] Step 7: Pour the connecting beam between the steel cofferdam and the caisson. After that, excavate the fill inside the steel cofferdam and pour the bottom sealing concrete.

[0014] Step 8: Pump water out of the inside of the steel cofferdam and pour the water intake and drainage head structure upwards;

[0015] Step 9: Construct the intake and drainage pipes and complete the connection between the intake and drainage pipes and the caisson.

[0016] Furthermore, the construction method of the caisson-type intake and drainage head facility within the outer perimeter weir provided by the present invention may also have the following features: Step 1, in the process of leveling the muddy surface at the bottom of the water, also includes excavation and reinforcement.

[0017] Furthermore, the construction method of the caisson-type intake and drainage head facility within the outer perimeter weir provided by the present invention may also have the following features: the steel cofferdam adopts a circular double-walled steel cofferdam.

[0018] Furthermore, the construction method of the caisson-type intake and drainage head facility inside the outer perimeter dam provided by the present invention may also have the following features: in step 3, the inside of the steel cofferdam is filled with filler material, which is sand or soil; the outside of the steel cofferdam is filled with bottom and surface protection material.

[0019] Furthermore, the construction method of the caisson-type intake and drainage head facility in the outer perimeter weir provided by the present invention may also have the following features: Step 6, pouring the bottom sealing structure in the caisson, includes pouring the bottom sealing concrete and the bottom slab in sequence.

[0020] Furthermore, the construction method of the caisson-type intake and drainage head facility in the outer perimeter weir provided by the present invention may also have the following features: the pouring of the intake and drainage head structure in step 8 includes the pouring of the bottom plate, side walls and partition walls.

[0021] Furthermore, the construction method of the caisson-type intake and drainage head facility within the outer perimeter weir provided by the present invention may also have the following features: in step 9, mechanical tunneling or mining methods are used to construct and connect the intake and drainage pipelines.

[0022] Furthermore, the construction method of the caisson-type intake and drainage head facility within the outer perimeter weir provided by the present invention also includes step 10: restoring the bottom mud surface and cutting and removing the upper part of the steel cofferdam.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] In the construction method of the caisson-type water intake and drainage head facility within the outer perimeter weir of this invention, the steel cofferdam is shallowly embedded in the soil, with low height and light weight. It can be self-floating or transported by boat and sunk on a leveled or reinforced underwater mud surface. Backfill material is then added inside the steel cofferdam, and the backfill surface is constructed using a method similar to that used for onshore caisson construction. This completes the sinking of the central vertical shaft water conveyance channel structure. Subsequently, soil is excavated inside the shaft and between the shaft and the outer perimeter weir, underwater concrete is used for bottom sealing, and the structure is rebuilt. The bottom of the caisson, the steel cofferdam, and the area between the caisson are all sealed with underwater concrete. The entire water intake structure is dry-constructed after bottom sealing, completely avoiding the construction risks associated with surface pits and water pressure at the bottom, significantly reducing the construction period and improving construction quality. Furthermore, after the overall structure is completed, the outer steel cofferdam can be cut off and recycled. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of step 1 of the construction method of the caisson-type intake and drainage head facility in the outer weir of the present invention, which involves leveling the mud surface at the bottom of the water.

[0026] Figure 2 This is a schematic diagram of the excavation and reinforcement step 1 in the construction method of the caisson-type intake and drainage head facility inside the outer weir of the present invention.

[0027] Figure 3 This is a schematic diagram of step 2 of the construction method of the caisson-type water intake and drainage head facility inside the outer weir in an embodiment of the present invention;

[0028] Figure 4 This is a schematic diagram of the circular double-walled steel cofferdam structure according to an embodiment of the present invention;

[0029] Figure 5 yes Figure 4 Enlarged view of a local structure in the middle;

[0030] Figure 6 This is a schematic diagram of step 3 of the construction method of the caisson-type water intake and drainage head facility inside the outer weir in an embodiment of the present invention;

[0031] Figure 7 This is a schematic diagram of step 4 of the construction method of the caisson-type water intake and drainage head facility inside the outer weir in an embodiment of the present invention;

[0032] Figure 8 This is a schematic diagram of step 4 of the construction method of the caisson-type water intake and drainage head facility inside the outer weir in an embodiment of the present invention;

[0033] Figure 9 This is a schematic diagram of step 6 of the construction method of the caisson-type water intake and drainage head facility inside the outer weir in an embodiment of the present invention;

[0034] Figure 10 This is a schematic diagram of step 7 of the construction method of the caisson-type water intake and drainage head facility inside the outer weir in an embodiment of the present invention;

[0035] Figure 11 This is a schematic diagram of step 8 of the construction method of the caisson-type water intake and drainage head facility inside the outer weir in an embodiment of the present invention;

[0036] Figure 12 This is a schematic diagram of step 9 of the construction method of the caisson-type intake and drainage head facility inside the outer weir in an embodiment of the present invention;

[0037] Figure 13 This is a schematic diagram of step 10 of the construction method of the caisson-type water intake and drainage head facility inside the outer weir in an embodiment of the present invention. Detailed Implementation

[0038] To make the technical means, creative features, objectives and effects of this invention easier to understand, the following embodiments, in conjunction with the accompanying drawings, will specifically illustrate the technical solution of this invention.

[0039] This embodiment provides a construction method for a caisson-type intake and drainage head facility within an outer perimeter weir, which includes the following steps:

[0040] Step 1: See Figure 1 Level the muddy surface at the bottom of the water. See also Figure 2 During the leveling process, appropriate excavation may be carried out if necessary, or reinforcement methods may be used to reduce the impact of excavation.

[0041] Step 2: See Figure 3 The steel cofferdam 2 was then placed on the beach at the leveled location.

[0042] The preferred steel cofferdam 2 is a circular double-walled steel cofferdam, the structure of which is as follows: Figure 4 and Figure 5 As shown, the steel cofferdam 2 includes an inner annular wall plate 21 and an outer annular wall plate 22. Horizontal radial supports 24 are arranged in a circular array between the inner and outer annular wall plates 21 and 22, respectively welded and fixed to the inner and outer annular wall plates 21 and 22. Horizontal diagonal supports 23 are also provided on the sides of the horizontal radial supports 24. Inner wall annular stiffening ribs 211 and inner wall vertical stiffening ribs 212 are welded and fixed to the inner wall plate 21. Outer wall annular stiffening ribs 221 and outer wall vertical stiffening ribs 222 are welded and fixed to the outer wall plate 22. A circular double-walled steel cofferdam is beneficial for stress distribution during the later filling stage. However, this is not a limitation; other shapes and materials of cofferdams can also be used in other embodiments.

[0043] Step 3: See Figure 6 The steel cofferdam is then filled both inside and outside. The inside of the steel cofferdam 2 is filled with filler material 3, which consists of sand, gravel, or soil. The outside of the steel cofferdam 2 is filled with bottom and surface protection material 4.

[0044] Step 4: See Figure 7 The first section of caisson 5 was poured inside the fill material of the steel cofferdam 2.

[0045] Step 5: See Figure 8 The caisson 5 is poured section by section and excavated for sinking. During construction, the underwater excavation surface 6 is dynamically controlled. If the soil has good impermeability, a drainage (dry excavation) sinking method can also be adopted according to the actual situation.

[0046] Step 6: See Figure 9 After the caisson 5 is lowered into place, the bottom sealing structure inside the caisson 5 is poured. The bottom sealing structure includes the bottom sealing concrete 7 and the bottom slab 8, which are poured in sequence.

[0047] Step 7: See Figure 10 Then, the connecting beam 9 between the steel cofferdam 2 and the caisson 5 was poured. After that, the filling material inside the steel cofferdam 2 was excavated and the bottom sealing concrete 7 was poured.

[0048] Step 8: See Figure 11 The water inside the steel cofferdam 2 is pumped out, and the bottom plate, side walls and partition walls of the water intake and drainage head structure 10 are poured upwards.

[0049] Step 9: See Figure 12 The intake and drainage pipeline 11 is constructed using mechanical tunneling or mining methods, and the connection between the intake and drainage pipeline 11 and the caisson 5 is completed.

[0050] Step 10: See Figure 13 The bottom mud surface 1 is restored, and the upper part of the steel cofferdam 2 is cut and removed. In this embodiment, the upper part of the steel cofferdam 2 is completely cut off in a ring shape, but this is not a limitation. In other embodiments, the water intake part can be partially cut off as needed.

[0051] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A construction method for a caisson-type intake and drainage head facility within an outer perimeter weir, characterized in that, Includes the following steps: Step 1: Level the muddy surface at the bottom of the water; Step 2: Place the steel cofferdam on the leveled area and let it sit on the beach; Step 3: Fill the inside and outside of the steel cofferdam separately; Step 4: The first section of the caisson is poured in the backfill inside the steel cofferdam; Step 5: Construct the caisson section by section and excavate to sink it; Step 6: After the caisson has sunk into place, pour the bottom sealing structure inside the caisson; Step 7: Pour the connecting beam between the steel cofferdam and the caisson. After that, excavate the fill inside the steel cofferdam and pour the bottom sealing concrete. Step 8: Pump water out of the inside of the steel cofferdam and pour the water intake and drainage head structure upwards; Step 9: Construct the intake and drainage pipes and complete the connection between the intake and drainage pipes and the caisson.

2. The construction method of the caisson-type intake and drainage head facility within the outer perimeter weir as described in claim 1, characterized in that: Step 1, in the process of leveling the muddy bottom surface, also includes excavation and reinforcement.

3. The construction method of the caisson-type intake and drainage head facility within the outer perimeter weir as described in claim 1, characterized in that: The steel cofferdam is a circular double-walled steel cofferdam.

4. The construction method of the caisson-type intake and drainage head facility within the outer perimeter weir as described in claim 1, characterized in that: In step 3, the inside of the steel cofferdam is filled with filler material, which is sand, gravel or soil; the outside of the steel cofferdam is filled with bottom and surface protection material.

5. The construction method of the caisson-type intake and drainage head facility within the outer perimeter weir as described in claim 1, characterized in that: Step 6 involves pouring the bottom sealing structure inside the caisson, which includes pouring the bottom sealing concrete and the bottom slab in sequence.

6. The construction method of the caisson-type intake and drainage head facility within the outer perimeter weir as described in claim 1, characterized in that: Step 8 involves the pouring of the water intake and drainage head structure, including the pouring of the base slab, side walls, and partition walls.

7. The construction method of the caisson-type intake and drainage head facility within the outer perimeter weir as described in claim 1, characterized in that: In step 9, mechanical tunneling or mining methods are used to construct and connect the intake and drainage pipelines.

8. The construction method of the caisson-type intake and drainage head facility within the outer perimeter weir as described in claim 1, characterized in that, Also includes: Step 10: Restore the bottom mud surface and cut and remove the upper part of the steel cofferdam.

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