Construction method of reinforced steel cofferdam with compartment concrete pouring in complex deep water environment

Abstract

This invention proposes a construction method for reinforced steel cofferdams with inter-compartmental concrete casting in complex deep-water environments. The method includes: intelligent manufacturing of the steel cofferdam; pre-assembly and permeability testing followed by transportation to the site; installation of steel cofferdam segments; construction of segmental transport support trusses; transportation of the first steel cofferdam segment; installation of guiding devices; lowering of the first steel cofferdam segment while simultaneously casting concrete in inter-compartmental sections to assist in sinking; assembly of the middle and top steel cofferdam segments; connection of the middle and bottom segments with inter-compartmental concrete casting; connection of the top and middle segments with inter-compartmental concrete casting; dredging within the cofferdam; pouring of the inner wall concrete; sealing the bottom of the steel cofferdam; construction of internal supports within the steel cofferdam; dewatering of the steel cofferdam; pouring of the foundation; and dismantling of the steel cofferdam. This method can improve the construction efficiency and engineering safety of double-walled steel cofferdams in complex deep-water environments.

Description

Technical Field

[0001] The invention relates to the technical field of bridge construction, in particular to a construction method for reinforced steel cofferdams involving compartment casting concrete in a complex deepwater environment. Background Art

[0002] In the construction of bridge foundations and other projects, the construction of deep-water steel cofferdams is crucial. The traditional method of deep-water steel cofferdam construction is to build an assembly platform on site, assemble the steel cofferdam, and lower it after completing the seepage test. However, this method has many limitations.

[0003] On the one hand, the on-site platform construction and on-site assembly are easily affected by natural environmental factors such as the weather on the day, resulting in reduced construction efficiency and delayed construction progress. On the other hand, the lowering system of the traditional double-walled steel cofferdam is not precise enough to control the lowering of the steel cofferdam, and it is difficult to meet the lowering control requirements under complex hydrological conditions. In addition, the traditional steel cofferdam relies on water injection to assist sinking during lowering. In deep water areas, the strength of the steel cofferdam will be affected by water pressure problems, causing structural problems and posing safety hazards. In river sections with a large difference between high and low water levels throughout the year, or in bridge foundations where the pier is buried at a deep depth, the water head difference and mud penetration depth are large during the construction of the pier steel cofferdam, which increases the difficulty and risk of construction. The selection and arrangement of the hoisting process for large-size cofferdams also become difficult and risky points.

[0004] In order to solve the above problems, a method of manufacturing steel cofferdams in the factory and then transporting them to the site has emerged, which to a certain extent avoids the impact of on-site weather and hydrological factors on the construction of steel cofferdams. However, the existing segmented transportation, assembly, and docking still have shortcomings, and need to be further optimized to achieve a more efficient, safer, and more convenient construction process. In this context, the present invention aims to solve the deficiencies in the prior art through innovative construction methods, promote the development of double-walled steel cofferdam construction technology in complex deepwater environments, improve construction efficiency and engineering safety, and develop an economical, environmentally friendly, and efficient steel sheet pile island cofferdam and construction method that can fully mobilize on-site resources. Summary of the invention

[0005] The embodiment of the present invention provides a construction method for reinforced steel cofferdams by casting concrete in compartments in a complex deepwater environment. It aims to address the problems of low construction efficiency due to the influence of the natural environment, inaccurate control of the lowering system, safety problems in deepwater areas due to water pressure, and the segmented transportation method of existing factories producing and transporting the cofferdams to the site.

[0006] In a first aspect, the present invention provides a construction method for a complex deepwater environment compartment casting concrete reinforced steel cofferdam, the method comprising the following steps:

[0007] S1. Intelligent manufacturing of steel cofferdam:

[0008] Collect hydrological data of the construction site, use design software to model multiple schemes, and continuously perform simulations to determine the final design scheme;

[0009] After the design is completed, various standard blocks of the steel cofferdam are produced, including the first section corner standard block, the first section middle standard block, the non-first section corner standard block, and the non-first section middle standard block;

[0010] S2. Pre-assembly, water seepage test and transportation to the site:

[0011] Each standard block of the steel cofferdam is pre-assembled and tested for water seepage in the factory, and then disassembled and transported to the construction site after the test;

[0012] S3. Install steel cofferdam segments:

[0013] Assemble the steel cofferdam on the shore of the construction site and conduct welding quality inspection and kerosene penetration test after assembly;

[0014] S4. Build the segment transport support truss:

[0015] Use disc-type scaffolding and steel pipe scaffolding for construction, divide the supporting trusses into external supports, internal supports and bottom plate steel pipe cages, and use external supports and internal supports to support the steel cofferdam;

[0016] S5. Transportation of the first section of steel cofferdam:

[0017] After the first section of the steel cofferdam is assembled on the shore, it is transported to the ship through the transport support truss, and the bottom plate steel pipe cage of the transport support truss is fixed to the ship's clamping plate;

[0018] S6. Install the guide device:

[0019] Several guide devices are set up on the outside of the casing to provide guidance and limit for the subsequent steel cofferdam sinking process;

[0020] S7. The first section of the steel cofferdam is lowered, and concrete is poured into the compartments to assist the sinking:

[0021] Remove the inner support of the supporting truss and lift the steel cofferdam to the designated location by floating crane;

[0022] After reaching the designated position, the steel cofferdam is lowered along the casing, and the guide device is used to guide and limit the steel cofferdam during the lowering process.

[0023] After lowering, it enters the sinking stage, during which concrete pouring is carried out simultaneously to ensure that the steel cofferdam can remain self-floating;

[0024] S8, assembly of middle section and top section steel cofferdam:

[0025] Same as the first section of steel cofferdam, the middle section and top section of steel cofferdam are assembled and then transported to the site;

[0026] S9. The middle section and the bottom section are connected and concrete is poured in the compartments:

[0027] The middle section is hoisted above the first section, connected with the first section and welded and tested for kerosene penetration. After the test is passed, it is sunk and concrete is poured in the compartments;

[0028] S10, the top section and the middle section are connected and concrete is poured in the compartments:

[0029] The same operation method as the middle section, connect the top section with the middle section, sink it and pour concrete in the compartment;

[0030] S11. Desilting inside the cofferdam:

[0031] After the bed is planted at the bottom of the steel cofferdam, desilting operations are carried out;

[0032] S12, sandwich wall concrete pouring:

[0033] After dredging is completed, concrete is poured in the compartments of the steel cofferdam;

[0034] S13, Steel cofferdam bottom seal:

[0035] Pouring the bottom concrete of the steel cofferdam;

[0036] S14. Construction of internal support for steel cofferdam:

[0037] Install internal supports;

[0038] S15, Steel Cofferdam Pumping:

[0039] After the bottom seal concrete reaches the designed strength, water is pumped out from the steel cofferdam. Each time a layer of water is pumped out, a layer of internal support is installed until the water inside the steel cofferdam is pumped out and the internal support is installed.

[0040] S16, foundation casting:

[0041] After the pumping and internal support construction is completed, the escalator is installed on the inner side of the steel cofferdam, and the casing and guide device are removed to start the cap casting operation. Each time a layer of cap is cast, a layer of internal support is cut off until all cap construction is completed;

[0042] S17, Steel Cofferdam Removal:

[0043] After the foundation construction is completed, the steel cofferdam is dismantled in blocks and hoisted and transported away to complete the construction.

[0044] Furthermore, in step S1, BIM software is used for modeling and simulation, and after the best solution is determined, finite element analysis software is used for analysis and adjustment to determine the final steel cofferdam design solution.

[0045] Furthermore, in step S1, the bottom plates of the first section corner standard block and the first section middle standard block are made into a blade angle style.

[0046] Furthermore, in step S2, each standard part of the steel cofferdam is fastened by threaded fasteners, and the threaded fasteners are screwed from top to bottom until all the threaded fasteners are tightened at the same time.

[0047] Furthermore, in step S4, external supports are installed on the outer wall of the steel cofferdam to support the steel cofferdam, and internal supports are installed inside the steel cofferdam to support it. The bottom plate steel pipe cage is a large-area foundation made of steel pipes, which is used to better provide stability for the internal and external supports.

[0048] Furthermore, in step S5, the steel cofferdam is transported onto the ship using a flatbed truck.

[0049] Furthermore, in step S7, when pouring concrete in the compartment, a centrally symmetrical steel cofferdam is used, first pouring the first section corner standard blocks, and then pouring the first section middle standard blocks.

[0050] Furthermore, in step S1, the outer walls of the first-section corner standard blocks and the first-section middle standard blocks are higher than the inner walls by a set height, and the outer walls of the non-first-section corner standard blocks and the non-first-section middle standard blocks are higher than the inner walls and the partition boards by a set height.

[0051] Furthermore, in step S8 and step S1, the outer walls of the first-section corner standard blocks and the first-section middle standard blocks are 50 cm higher than the inner walls, and the outer walls of the non-first-section corner standard blocks and the non-first-section middle standard blocks are 50 cm higher than the inner walls and partition boards.

[0052] Furthermore, in step S1, the bottoms of the first section corner standard block and the first section middle standard block are provided with cutting edges.

[0053] The main contributions and innovations of the present invention are as follows:

[0054] 1) The present invention uses intelligent manufacturing technology. By using BIM and other software, the specific hydrological environment of the construction site can be simulated to determine the size of the standard block of the steel cofferdam, ensuring safety, while also saving design costs and time, and effectively speeding up engineering efficiency. For example, the piers of a certain large bridge project adopted BIM design for the entire construction process, reducing the use of steel by 105 tons, thereby reducing material costs by 1.26 million yuan and shortening the construction period by about 30%.

[0055] 2) The present invention adopts a method of block production and segment assembly. The segment manufacturing is completed by assembling and welding on the shore. There is no need to assemble on the construction site, and there is no need to build an installation platform on site, which speeds up the construction efficiency and saves time.

[0056] 3) The present invention adopts a combination of disc-type scaffolding and steel pipe scaffolding, which shortens the erection and disassembly time of the transport support truss. Compared with the traditional erection method, the erection time is reduced by about 40%. The disassembly time is reduced by about 30%, which shortens the overall transportation time by about 25%, significantly improving work efficiency and saving time costs.

[0057] 4) The present invention adopts a compartment concrete pouring technology. By pouring concrete in compartments when the steel cofferdam sinks, the sinking of the steel cofferdam is assisted and the strength of the steel cofferdam is enhanced, which speeds up the construction efficiency and ensures the construction safety.

[0058] 5) The present invention adopts the dredging technology of the surrounding environment inside the weir. The dredging work inside the cofferdam is carried out by combining a long-arm excavator and a telescopic arm excavator. After cleaning to the bottom, the diver uses a high-pressure water gun and a steel brush to carefully clean the blade foot, the surrounding area of ​​the casing and the base of the steel cofferdam to prevent the formation of weak areas and ensure that the bottom sealing concrete is closely combined with the pile foundation and the cofferdam. The silt inside the cofferdam is removed by the combined efforts of man and machine, which speeds up the construction efficiency.

[0059] 6) The present invention adopts the steel cofferdam posture capture and dynamic deviation correction technology. When each section of steel is docked, the laser device is used to assist in positioning. At the same time, the scanning device is used to dynamically capture the steel cofferdam and output instructions to the floating crane driver and the operator of the guide device in real time. The laser device assists the operator in docking and positioning, while the scanning device assists the floating crane driver and the hydraulic device operator in making real-time corrections. The two sets of equipment reduce construction problems caused by inconvenient on-site communication and improve work efficiency.

[0060] 7) The present invention adopts the cofferdam bottom sealing construction technology, which keeps the water level inside and outside the cofferdam basically consistent by measuring the water head difference inside and outside the cofferdam at any time and draining water out in time. Make more concrete test blocks. After the bottom sealing concrete is poured, put the concrete test blocks into the water inside the cofferdam and make test blocks for curing under the same conditions, so as to accurately grasp the strength of the bottom sealing concrete and ensure the construction safety.

[0061] 8) The present invention adopts a cofferdam lowering guide device with a fixed pulley and a hydraulic device, which not only leaves a safe distance between the steel cofferdam and the casing, but also reduces the resistance to the lowering of the cofferdam due to the existence of the fixed pulley; when the cofferdam deviates from the established lowering route due to external force, multiple hydraulic devices can provide force in the opposite direction of the displacement of the steel cofferdam, guide the cofferdam to its original position, facilitate the cofferdam lowering work, save the time of cofferdam posture adjustment, and improve work efficiency.

[0062] The details of one or more embodiments of the invention are set forth in the following drawings and description so that other features, objects, and advantages of the invention are more readily apparent. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0064] Figure 1 It is the structural diagram of the first section of the steel cofferdam of the present invention;

[0065] Figure 2 It is a non-first section structural diagram of the steel cofferdam of the present invention;

[0066] Figure 3 This is a structural diagram of a non-first-section corner standard block of the present invention;

[0067] Figure 4 It is a standard block structure diagram of the middle part of the non-first section of the present invention;

[0068] Figure 5 It is a block-assembly segment node a diagram of the present invention;

[0069] Figure 6 It is a diagram of the segment transport support truss of the present invention;

[0070] Figure 7 It is a top view of the segment compartment of the steel cofferdam of the present invention;

[0071] Figure 8 It is a guide device diagram of the present invention;

[0072] Fig. 9 It is a construction flow chart of the present invention.

[0073] In the figure: 1. Standard block for the first section corner; 2. Standard block for the middle of the first section; 3. Blade angle; 4. Standard block for the non-first section corner; 5. Standard block for the non-first section middle; 6. Inner wall of the arc; 7. Threaded steel bar; 8. Partition board; 9. Operation window; 10. Outer wall of the arc; 11. Bolt; 12. Outer wall of the straight plate; 13. Inner wall of the straight plate; 14. Right standard block; 15. Bolt a; 16. Small hole of the partition board; 17. Left standard block; 18. Screw Bolt b; 19, external support column; 20, steel cofferdam segment; 21, internal support column; 22, internal support unit; 23, bottom plate steel pipe cage; 24, protective slope; 25, angle steel; 26, horizontal rod; 27, deck; 28, catapult; 29, diagonal brace; 30, fixed pulley; 31, diagonal support rod; 32, horizontal support rod; 33, casing; 34, hydraulic device; 1~4A, corner partition; 1~4B, middle partition. DETAILED DESCRIPTION

[0074] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the following exemplary embodiments do not represent all implementations consistent with one or more embodiments of this specification. Instead, they are merely examples of devices and methods consistent with some aspects of one or more embodiments of this specification as detailed in the appended claims.

[0075] It should be noted that: in other embodiments, the steps of the corresponding method are not necessarily performed in the order shown and described in this specification. In some other embodiments, the steps included in the method may be more or less than those described in this specification. In addition, a single step described in this specification may be decomposed into multiple steps for description in other embodiments; and multiple steps described in this specification may be combined into a single step for description in other embodiments.

[0076] The present invention aims to propose a construction method for a complex deepwater environment partition casting concrete reinforced steel cofferdam. Specifically, referring to Figures 1 to 9 , the method comprises the following steps:

[0077] S1. Intelligent manufacturing of steel cofferdams;

[0078] In this embodiment, during intelligent manufacturing, hydrological data of the construction site should be collected, including water depth, water flow velocity, tidal cycle, wave height, etc. The data is modeled by DTM through GIS software, and then the DTM model is imported into the BIM model. In the BIM software, the collected hydrological data is input, including water flow velocity, direction, wave parameters, etc., and tidal parameters and wind load parameters are also set. Then run the fluid dynamics simulation module in the BIM software to identify potential risk points such as local stress concentration, excessive deformation, etc., for the stress condition and force distribution of the steel cofferdam in a complex deepwater environment. Finally, adjust the design parameters of the steel cofferdam according to the above simulation results, and repeat the simulation process until the optimal solution is found.

[0079] In the deep-water foundation construction of a cross-river bridge, it is necessary to design and construct a double-walled steel cofferdam. According to the on-site hydrological conditions, the overall horizontal plane size of the steel cofferdam is initially planned to be 20m×20m and the height is 25m. A three-dimensional model of the steel cofferdam is created in the BIM software and the on-site DTM model is imported. In the BIM software, the water flow velocity is set to 2m / s, the wave height is 1.5m, the period is 8s, and the tidal range is ±3m. Then a simulation is performed to analyze the stability and stress of the steel cofferdam at different water levels. The simulation results show that under extreme hydrological conditions, large stress concentration occurs in some areas of the bottom and side walls of the steel cofferdam. In order to improve stability, it is decided to increase the number of compartments from the original design of 6 to 8, and appropriately thicken the bottom and side wall plates. After many simulations, it is finally determined that the size of the middle standard block of each segment of the steel cofferdam is 5m×2m×5m, and a total of 4 middle standard blocks are required to be spliced.

[0080] Through BIM software simulation, the project discovered potential problems in advance, avoiding the time wasted by on-site tests and adjustments in traditional design methods. Compared with traditional methods, BIM technology shortened the design cycle by about 30%. At the same time, after adopting BIM technology, the material consumption of steel cofferdam was reduced by about 10%, and the total construction cost was reduced by about 5%.

[0081] Among them, Figure 1~2 As shown, the first section of the steel cofferdam is welded by multiple first section corner standard blocks 1 and multiple first section middle standard blocks 2, and a blade angle 3 is set at the bottom of the first section standard block. The non-first section of the steel cofferdam is welded by multiple non-first section corner standard blocks 4 and non-first section middle standard blocks 5. Workers can tighten bolts a15 and bolts b18 through the operating windows 9 on both sides to apply force to the steel cofferdam standard blocks on both sides, so as to better fit and facilitate welding. The outer wall of the first section standard block needs to be 50 cm higher than the inner wall for better docking with the middle section. The outer wall of the non-first section standard block needs to be 50 cm higher than the inner wall, and the length of the inner and outer walls is kept consistent, which facilitates the docking of the middle section, the first section and the top section.

[0082] like Figure 3 As shown, the non-first section corner standard block of the steel cofferdam is composed of an arc outer wall 10, an arc inner wall 6, a partition plate 8, and internal and external vertical ribs, horizontal ring plates, and horizontal diagonal braces. The partition plates 8 must be provided with a number of partition plate holes 16 for inserting threaded steel bars 7. At the same time, the arc inner wall 6 and the arc outer wall 10 must also be provided with operation windows 9 at corresponding positions for workers to tighten the bolts 11 embedded in the threaded steel bars 7. At the same time, the positions of the partition plate holes 16 should be aligned to prevent the threaded steel bars 7 from being unable to accurately pass through the corresponding two partition plate holes 16. The entire arc outer wall 10 is fifty centimeters higher than the partition plate 8 and the arc inner wall 6, and the length of the inner and outer walls is kept consistent, which facilitates the docking of the middle section, the first section, and the top section.

[0083] like Figure 4 As shown, the standard block in the middle of the non-first section of the steel cofferdam is composed of a straight plate outer wall 12, a straight plate inner wall 13, a partition plate 8, and internal and external vertical ribs, a horizontal ring plate, and a horizontal diagonal brace. The partition plate 8 must be provided with a number of partition plate holes 16 for inserting the threaded steel bar 7. At the same time, the arc inner wall 6 and the arc outer wall 10 must also be provided with operation windows 9 at corresponding positions for manually tightening the bolts 11 embedded in the threaded steel bar 7, so as to apply force to assist the block installation of each standard block. At the same time, the positions of the partition plate holes 16 should be aligned to prevent the threaded steel bar 7 from being unable to accurately pass through the corresponding two partition plate holes 16. The entire straight plate outer wall 12 is fifty centimeters higher than the partition plate 8 and the straight plate inner wall 13, and the length of the inner and outer walls is kept consistent, which facilitates the docking of the middle section, the first section, and the top section.

[0084] like Figure 5 As shown, after the standard blocks are made, the bolt operation is performed during the segment assembly. The threaded steel bar 7 is passed through the partition plate small hole 16, and respectively through the right partition plate small hole 16 of the left standard block 17 and the left partition plate small hole of the right standard block 14. After that, the bolts a15 and the bolts b18 are tightened through the operation window 9 to make the two standard blocks fit each other. The operation of tightening the bolts 11 should not tighten the bolts 11 of a pair of partition plate small holes 16 first and then tighten the remaining partition plate small holes 16, but should be slowly screwed from top to bottom until all the bolts 11 are tightened at the same time. This ensures that there will be no situation where the bolts 11 behind cannot be tightened due to the prior tightening of a partition plate small hole 16.

[0085] S2, transport to the site after pre-assembly and water seepage test;

[0086] In this embodiment, the installation of the segments is carried out after each standard block is transported to the shore of the construction site and assembled on the shore, performing the following operations:

[0087] Taking the central axis of the cofferdam as the reference, the position line of the cofferdam side plate is laid out on the platform surface. The layout should be made according to the size of the drawing; if the assembly platform on the shore is uneven, a steel pad can be set to level the steel cofferdam; the bottom section steel cofferdam is assembled in blocks by crawler crane. During assembly, the small holes 16 of the partition plates of adjacent standard blocks are aligned to facilitate workers to insert threaded steel bars 7, and the bolts 11 are tightened through the operation window 9 to make the steel cofferdam standard blocks fit tightly; during assembly, the cofferdam should be assembled in accordance with the principle of symmetry and in the order of "first assembling the long side and then the short side"; after the above standard blocks form the steel cofferdam segment 20, the joints of all standard blocks are welded, and after welding, the quality of the weld itself is inspected and the kerosene penetration test is performed. The kerosene penetration test steps are: apply lime powder on one side of the weld and kerosene on the other side to observe its penetration. If it penetrates to the reverse side, make a mark, scrape off the weld there, and re-weld it according to the regulations, but do not overlay it.

[0088] S3, install steel cofferdam segments;

[0089] S4, build segment transport support trusses;

[0090] In this embodiment, if Figure 6 As shown, the construction of the segment transport support truss is made of a variety of scaffolding spliced ​​together, using disc-type scaffolding and steel pipe scaffolding, and the support truss is divided into an outer support and an inner support as well as a bottom plate steel pipe cage 23. The outer support is formed by connecting the steel pipe outer support column 19 through a steel pipe horizontal rod 26 to support the steel cofferdam segment 20 on the outer wall of the steel cofferdam, and the inner support is supported inside the steel cofferdam, and the inner support is built by a disc-type scaffolding. The bottom plate steel pipe cage 23 is a large-area foundation made of steel pipes, which is used to better provide stability for the inner and outer supports. The bottom plate steel pipe cage 23 needs to be overlapped vertically with steel pipes and built with buckles, and is equipped with some diagonal rod supports to provide stability. The bottom plate steel pipe cage 23 is mainly to provide some connections between the steel cofferdam segment 20 and the deck 27. The bottom plate steel pipe cage 23 is connected to the deck 27 through angle steels 25 and bolts, which effectively prevents sliding and displacement during transportation. All the columns 19 of the outer and inner supports are connected to the bottom plate steel pipe cage 23 through buckles, so that the inner and outer supports become a whole. The outer supports need to be made of steel pipes as columns 19, and more diagonal braces 29 need to be set up in the passage space of the traditional outer frame to increase the stability of the entire truss outer support. The outer supports need to be made of steel pipes as 50° scissor braces.

[0091] Preferably, after the steel cofferdam segment 20 and the supporting truss are subsequently transported to the deck, they need to be reinforced with a guy brace 28. The scissor brace should comply with the "General Specification for Construction Scaffolding" GB 55023-2022. The guy brace 28 needs to be evenly distributed at the intersection of the horizontal bars 26 on the inner and outer sides of the outer support and the outer support column 19 to provide diagonal support. The column needs to be composed of four steel pipe vertical bars connected by horizontal bars. The inner support is constructed by a disc-shaped scaffolding. Twelve disc-shaped scaffoldings form a cubic inner support unit 22. The inner support formed by the inner support unit 22 is connected to the bottom plate steel pipe cage 23 by a fastener, and is also connected to the inner support column 21 by a fastener. When transporting the first section of the steel cofferdam, the inner support needs to be provided with a protective slope 24 at the edge corner of the steel cofferdam to protect the edge corner 3.

[0092] For example, during the construction of a large cross-sea bridge, a double-walled steel cofferdam is required in a deep-water area, where the hydrological conditions are complex, the tidal effect is significant, and there are wind and wave influences. In order to ensure the stability and safety of the steel cofferdam during transportation and installation, the construction method of the present invention is adopted, and special attention is paid to the design and application of the transport support truss.

[0093] The transport support truss protects the stability and safety of the steel cofferdam in complex deep-water environments, especially in conditions of strong winds and waves. The combined design of internal and external supports can significantly reduce the shaking and displacement of the steel cofferdam, and the protective slope 24 is set to avoid collision and wear during transportation.

[0094] The truss adopts a combination of disc-type scaffolding and steel pipe scaffolding, which shortens the erection and disassembly time of the transport support truss. Compared with the traditional erection method, the erection time is reduced by about 40%. The disassembly time is reduced by about 30%, which shortens the overall transportation time by about 25%.

[0095] S5, transportation of the first section of steel cofferdam;

[0096] In this embodiment, when the first section of the cofferdam is transported, the cofferdam segment 20 and the supporting truss are rolled onto the ship together, and a longitudinal loading scheme is adopted, that is, the stern of the barge is brought against the dock. Before the cofferdam is loaded onto the ship, the barge is in place in advance, and when the height difference between the barge deck 27 and the shore plane is within 50 mm, roll-on / roll-off loading begins.

[0097] During the loading process, the flatbed truck should move forward steadily at a low speed, maintaining a uniform speed of 2m / min until it reaches the designated position. After the flatbed truck carries all the steel cofferdams onto the ship, the steel cofferdams are transported to the designated position, and the steel cofferdams are slowly lowered through the hydraulic lifting function of the flatbed truck. The steel cofferdams and trusses are placed on the steel piers on the ship deck, and the steel piers are set on both sides of the flatbed truck. After the first section of the steel cofferdam and truss lands, the steel pipe cage 23 at the bottom of the truss and the ship deck 27 are fixed by angle steel 25 and bolts to ensure stability during transportation. At the same time, a steel pipe is used to set a brace 28 at the outer support of the truss. The brace 28 needs to be evenly distributed at the intersection of the horizontal bars and columns on the inner and outer sides of the outer support to provide oblique support.

[0098] S6. Install the guide device;

[0099] In this embodiment, if Figure 8 As shown, before the steel cofferdam is lowered, multiple guide devices need to be set up on the outside of the casing 33. The guide devices are made of fixed pulleys 30, horizontal support rods 32, oblique support rods 31 and hydraulic devices 34. The guide device is installed on the outside of the casing 33, the fixed pulley 30 is fixed on the horizontal support rod 32, the oblique support rod 31 provides support for the horizontal support rod 32, and the hydraulic device 34 is installed on the horizontal support rod 32 to provide guidance and limit for the subsequent steel cofferdam sinking process. When the cofferdam is lowered and deviates in a certain direction, the hydraulic devices 34 of the multiple guide devices apply force in the opposite direction of the cofferdam deviation to ensure that the cofferdam is lowered according to the established position, and the fixed pulley reduces the friction when the cofferdam is lowered.

[0100] S7. The first section of the steel cofferdam is lowered, and concrete is poured into the compartments to assist the sinking;

[0101] In this embodiment, the lowering of the first section of the steel cofferdam is divided into three stages: the steel cofferdam lifting stage, the steel cofferdam lowering stage, and the compartment concrete pouring stage.

[0102] For the lifting stage of the steel cofferdam: the inner support of the fixed steel cofferdam needs to be removed first, and the steel cofferdam needs to be lifted to the designated position by a floating crane. During the lifting, in order to solve the problem of easy deformation of the steel cofferdam during the lifting process, two layers of steel pipes should be set to support the long side, and two layers of steel pipe angle braces should be set at the corners. The size of the steel pipe can be calculated in advance through BIM to obtain the required size of the corresponding steel cofferdam. The on-site command station is located at the top of the cofferdam, and the on-site deputy command station is located on the large floating crane. The surveyors observe the horizontal condition of the cofferdam at the existing dock control points and measurement control piles to ensure that the lifting speed of the two floating cranes is consistent.

[0103] During the steel cofferdam lowering stage: the floating crane lifts the cofferdam as a whole and moves it to the designated position synchronously, then lowers it along the steel casing to ensure that it does not hit the casing. Before the cofferdam is lowered, the dimension lines must be painted on the outer wall of each section of the cofferdam, and the sinking height is controlled by the dimension lines during the lowering process. In order to ensure that the cofferdam is self-floating and stable when each section of the cofferdam is connected, and to maintain a 1.5m high freeboard height for easy welding of the joint seams, the sinking process must be calculated in detail (compartment pouring concrete, cofferdam sinking height, etc.), and adjusted in real time. The elevation and plane position of the top surface of the cofferdam must be measured for each sinking to ensure that the requirements of the specifications are met before construction can continue.

[0104] For the partition concrete pouring stage: During the sinking process, the partition concrete pouring needs to be carried out simultaneously. The steel cofferdam should be poured in a central symmetrical position. The corner partitions 1A and 3A can be poured first, and then the partitions 2A and 4A. Then pour the middle partitions 1B and 3B, and finally pour 2B and 4B. It is worth noting that the volume of concrete needs to be accurately calculated. When calculating the volume of concrete, for simple geometric shapes, the formula can be directly used: volume = length × width × height, while for partitions with arcs, the formula needs to be used: volume = bottom area × height. The "height" in the formula (hereinafter referred to as The determination of the steel cofferdam (replacement) requires that the sum of the self-weight of the steel cofferdam and the weight of the concrete is less than the buoyancy given to the steel cofferdam by the on-site water, so as to ensure that the steel cofferdam can float on its own and ensure the subsequent docking. The buoyancy calculation formula is: , It is the volume of the steel cofferdam below the water surface.

[0105] The deadweight of the steel cofferdam can be obtained at the beginning of the design, and the weight of the concrete can be calculated by the formula When calculating the volume of concrete, it is necessary to allow The maximum h can be obtained. When pouring the partition concrete at the end, the concrete should be Less than h, and ensure that the steel cofferdam is exposed above the water surface to facilitate subsequent docking. The above formula is only a determination method, but in actual engineering, according to the pouring of concrete, it will lead to and At the same time, in actual engineering, concrete has a certain loss. When calculating the volume, a certain excess coefficient needs to be added, usually 5%-10%, to ensure that the amount of concrete required for construction is sufficient.

[0106] The calculation of the above data needs to be carried out according to the design drawings, specifications, and actual conditions on site. The design drawings will detail the key information such as the size, shape and concrete strength grade of the compartment. The construction specifications have clear provisions on the loss coefficient and expansion coefficient during the concrete construction process. These provisions are an important basis for calculating the volume of concrete. To ensure the accuracy of the calculation, the size of the compartment needs to be measured on site, and the calculation parameters need to be adjusted according to the measurement results.

[0107] Preferably, in order to ensure the self-floating of the steel cofferdam, its self-floating performance should be fully considered during the design stage of the steel cofferdam, and its self-floating performance should be improved by optimizing the steel cofferdam structure. At the same time, according to construction needs, the volume of concrete poured in the steel cofferdam compartment should be adjusted in time to ensure self-floating. At the same time, as when docking with the steel cofferdam segment, the scanning device is used to capture the posture of the self-floating steel cofferdam. Once an abnormality is found, measures are taken immediately to make adjustments to ensure safe self-floating.

[0108] S8, assembly of middle section and top section steel cofferdam;

[0109] In this embodiment, the middle section and top section steel cofferdams are assembled, just like the first section steel cofferdam. The middle section and top section steel cofferdams are assembled into sections on the shore by non-first section corner standard blocks 4 and non-first section middle section standard blocks 5, and then transported to the construction site by ship. The non-first section middle section standard blocks 5 and non-first section corner standard blocks 4 need to make the outer wall 50 centimeters higher than the inner wall, and keep the inner and outer wall lengths consistent, which facilitates the docking of the middle section, the first section and the top section. The requirements for splicing the middle section and the top section are consistent with those for the first section steel cofferdam. Finally, the middle section and the top section steel cofferdam are subjected to a kerosene penetration test. The kerosene penetration test steps are: apply lime powder on one side of the weld and kerosene on the other side, and observe its penetration. If it penetrates to the reverse side, make a mark, remove the weld at that place, and re-weld it according to regulations, but it cannot be surfacing welded.

[0110] S9, the middle section and the bottom section are connected and concrete is poured in the compartments;

[0111] In this embodiment, when the middle section is docked with the bottom section and concrete is poured in the compartment, the middle section needs to be hoisted by a floating crane. When docking with the first section, a laser device can be used to assist in positioning. At the same time, relying on a scanning device, through the dynamic capture of the steel cofferdam of the middle section, real-time instructions are output to the floating crane driver, and also transmitted to the operator of the guide device, so that the floating crane driver and the hydraulic device operator can make correct instructions to enable the middle section and the first section to dock quickly. In actual engineering, the dynamic capture system of the steel cofferdam of the middle section monitors the posture changes of the steel cofferdam in real time. Once a problem is found (such as the inclination rate exceeds 1%), the observation device immediately issues instructions to the floating crane driver and the operator of the guide device for multi-directional adjustments. According to actual engineering data statistics, the use of this technology can shorten the correction time by about 30%.

[0112] When the middle section and the first section are butt-jointed, the butt joints are welded by relying on their own weight. After welding is completed, a watertight test is also conducted by the kerosene penetration method. Only after the test is successful can the sinking be continued. During the sinking process, it is necessary to pour the partition concrete at the same time. The steel cofferdam should be poured in a central symmetrical position. The partitions 1A and 3A can be poured first, and then the partitions 2A and 4A. Then pour the partitions 1B and 3B, and finally pour 2B and 4B. The concrete volume calculation is consistent with the calculation in Example 11. Note that when calculating the self-weight of the concrete and the steel cofferdam, the self-weight of the middle section steel cofferdam needs to be added.

[0113] S10, the top section and the middle section are connected and concrete is poured in the compartments;

[0114] In this embodiment, the top section is butted with the middle section and the concrete is poured in the compartments. The top section needs to be hoisted by a floating crane. When it is butted with the middle section, a laser device can be used to assist in positioning. At the same time, a scanning device is used to capture the dynamics of the steel cofferdam of the top section, and a command is output to the floating crane driver in real time. At the same time, it is also transmitted to the operator of the guide device, so that the floating crane driver and the hydraulic device operator can make correct commands to enable the top section and the middle section to be quickly butted. When the top section and the middle section are butted, the butt joint is welded by relying on its own weight. After the welding is completed, a watertight test is also performed using the kerosene penetration method. Only after the test is successful can the sinking be continued. During the sinking process, it is necessary to pour concrete in the compartments at the same time. The steel cofferdam should be poured in a central symmetrical position. The compartments 1A and 3A can be poured first, and then the compartments 2A and 4A can be poured. Then the compartments 1B and 3B are poured, and finally 2B and 4B are poured.

[0115] S11, dredging inside the cofferdam;

[0116] In this embodiment, when dredging the cofferdam, after the steel cofferdam is planted, a combination of a long-arm excavator and a telescopic-arm excavator is used to perform dredging work in the cofferdam. After cleaning to the bottom, divers use high-pressure water guns and steel brushes to carefully clean the steel cofferdam blade foot, the surrounding area of ​​the casing and the base to prevent the formation of weak areas and ensure that the bottom seal concrete is tightly combined with the pile foundation and the cofferdam. The space between the steel casings and between the steel casings and the cofferdam is limited, so a small bucket can be made to work in areas with limited space. If a major flood occurs at the bridge site after the top section of the cofferdam is assembled and lowered, resulting in siltation in the cofferdam trench, the excavator cannot clean the cofferdam trench area, and an air compressor air lift reverse circulation process is used on site, and divers use high-pressure water guns to cooperate in the treatment. According to the comparison of actual engineering data, the dredging time is shortened by about 50% after the above technology is adopted, and the dredging is more thorough.

[0117] S12, pouring of sandwich wall concrete;

[0118] In this embodiment, when pouring the sandwich wall concrete, the steel cofferdam is accurately positioned and placed, and then C25 concrete is poured in the compartment. The underwater concrete pouring method is adopted, and the pouring is symmetrical, and the height difference of the concrete pouring of adjacent compartments is controlled to be about 1m. The concrete pouring height is generally controlled to be flush with the top elevation of the cap.

[0119] S13, steel cofferdam bottom seal;

[0120] In this embodiment, when performing the bottom sealing operation of the steel cofferdam, attention should be paid to the pouring sequence: rush from one end of the cofferdam to the other end, and pour in place at one time. The number of distribution points should be calculated and arranged in combination with the flow radius of the concrete, and the top surface elevation of the concrete at the pouring point should be tracked and detected in time to prevent the concrete from being too high, affecting the later construction of the platform, or the thickness of the bottom sealing is insufficient, affecting the safety of flood control and the risk of later construction of the platform. While pouring the bottom sealing concrete, the water head difference inside and outside the cofferdam should be measured at any time, and the water should be drained out in time to keep the water level inside and outside the cofferdam basically consistent. Make more concrete test blocks. After the bottom sealing concrete is poured, put the concrete test blocks in the water in the cofferdam and make the same condition curing test blocks to accurately grasp the strength of the concrete. Under normal circumstances, pumping can be carried out seven days after the bottom sealing. According to the statistics of actual engineering data, the strength of the concrete test blocks cured under the same conditions can meet the design requirements, and the discreteness is small (the standard deviation is generally less than 5MPa), indicating that the concrete quality is stable and reliable.

[0121] At the same time, when encountering problems: If partial water leakage occurs, do not forcibly block or divert it. You can use the reserved 20-30cm height to make a permeable layer to collect the water in one location and pump it away.

[0122] S14, construction of internal support for steel cofferdam;

[0123] In this embodiment, when the inner support of the steel cofferdam is constructed, the inner support can be constructed simultaneously with the pumping of water from the cofferdam. For each layer of water pumped out, one layer of inner support is welded. When welding the inner support, it must be accurately positioned to ensure that the center line of the steel pipe is consistent with the center line of the purlin and is horizontal. The compartments must be reinforced at the corresponding positions of the inner support.

[0124] S15, steel cofferdam pumping;

[0125] In this embodiment, when pumping water from the steel cofferdam, after the bottom concrete reaches the designed strength, the communicating vessel is closed and the water in the cofferdam is pumped out. Water should be pumped out according to the internal support construction until the water in the cofferdam is drained out. When pumping water from the steel cofferdam, the deformation of the steel cofferdam wall should be observed. If any abnormality occurs, pumping should be stopped immediately. The water level in the sandwich wall should be adjusted according to the actual water level, with the control principle of half the difference in water head between the inside and outside of the cofferdam.

[0126] S16, pouring of foundation cap;

[0127] In this embodiment, when pouring the cap, after pumping is completed, an escalator is installed on the inner side of the cofferdam, the steel casing and the guide device are cut off, the pile head is cleaned, the steel bars are tied, and the first layer of the cap (2.5m) concrete is poured. After the first layer of the cap reaches the design strength, the first layer of internal support is cut off, and then the second layer of the cap steel bars are tied, and the second layer of the cap (2.5m) concrete is poured.

[0128] S17, steel cofferdam removal.

[0129] In this embodiment, when the steel cofferdam is dismantled, the steel cofferdam dismantling construction is carried out according to the general idea of ​​"cutting in blocks, dismantling in blocks, and ensuring safety". The steel cofferdam is based on the top surface elevation of the pedestal, and the part above the reference elevation is cut and dismantled in blocks, and the steel cofferdam wall panels cut in blocks are hoisted by crawlers.

[0130] Those skilled in the art should understand that the technical features of the above embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0131] The above embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present invention. It should be pointed out that, for those of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the attached claims.

Claims

1. A construction method for casting concrete reinforced steel cofferdam in a complex deepwater environment, characterized in that: The following steps are involved: S1. Intelligent manufacturing of steel cofferdam: Collect hydrological data of the construction site, and use BIM software for modeling and simulation. After determining the best solution, use finite element analysis software for analysis and adjustment to determine the final steel cofferdam design solution; After the design is completed, various standard blocks of the steel cofferdam are made, including the first section corner standard block, the first section middle standard block, the non-first section corner standard block, and the non-first section middle standard block; the bottom plates of the first section corner standard block and the first section middle standard block are made into blade angle style; S2. Pre-assembly, water seepage test and transportation to the site: Each standard block of the steel cofferdam is pre-assembled and tested for water seepage in the factory, and then disassembled and transported to the construction site after the test; S3. Install steel cofferdam segments: Assemble the steel cofferdam on the shore of the construction site and conduct welding quality inspection and kerosene penetration test after assembly; S4. Build the segment transport support truss: Use disc-type scaffolding and steel pipe scaffolding for construction, divide the supporting trusses into external supports, internal supports and bottom plate steel pipe cages, and use external supports and internal supports to support the steel cofferdam; S5. Transportation of the first section of steel cofferdam: After the first section of the steel cofferdam is assembled on the shore, it is transported to the ship through the transport support truss, and the bottom plate steel pipe cage of the transport support truss is fixed to the ship's clamping plate; S6. Install the guide device: Several guide devices are set up on the outside of the casing to provide guidance and limit for the subsequent steel cofferdam sinking process; S7. The first section of the steel cofferdam is lowered, and concrete is poured into the compartments to assist the sinking: Remove the inner support of the supporting truss and lift the steel cofferdam to the designated location by floating crane; After reaching the designated position, the steel cofferdam is lowered along the casing, and the guide device is used to guide and limit the steel cofferdam during the lowering process. After lowering, it enters the sinking stage, during which concrete pouring is carried out simultaneously to ensure that the steel cofferdam can remain self-floating; S8, assembly of middle section and top section steel cofferdam: Same as the first section of steel cofferdam, the middle section and top section of steel cofferdam are assembled and then transported to the site; S9. The middle section and the bottom section are connected and concrete is poured in the compartments: The middle section is hoisted above the first section, connected with the first section and welded and tested for kerosene penetration. After the test is passed, it is sunk and concrete is poured in the compartments; S10, the top section and the middle section are connected and concrete is poured in the compartments: The same operation method as the middle section, connect the top section with the middle section, sink it and pour concrete in the compartment; S11. Desilting inside the cofferdam: After the bed is planted at the bottom of the steel cofferdam, desilting operations are carried out; S12, sandwich wall concrete pouring: After dredging is completed, concrete is poured in the compartments of the steel cofferdam; S13, Steel cofferdam bottom seal: Pouring the bottom concrete of the steel cofferdam; S14. Construction of internal support for steel cofferdam: Install internal supports; S15, Steel Cofferdam Pumping: After the bottom seal concrete reaches the designed strength, water is pumped out from the steel cofferdam. Each time a layer of water is pumped out, a layer of internal support is installed until the water inside the steel cofferdam is pumped out and the internal support is installed. S16, foundation casting: After the pumping and internal support construction is completed, the escalator is installed on the inner side of the steel cofferdam, and the casing and guide device are removed to start the cap casting operation. Each time a layer of cap is cast, a layer of internal support is cut off until all cap construction is completed; S17, Steel Cofferdam Removal: After the foundation construction is completed, the steel cofferdam is dismantled in blocks and hoisted and transported away to complete the construction.

2. The method for constructing a complex deepwater environment compartment concrete reinforced steel cofferdam as claimed in claim 1, characterized in that: In step S2, each standard part of the steel cofferdam is fastened by threaded fasteners, and the threaded fasteners are screwed from top to bottom until all the threaded fasteners are tightened at the same time.

3. The method for constructing a complex deepwater environment compartment concrete reinforced steel cofferdam as claimed in claim 1, characterized in that: In step S4, the outer support is installed on the outer wall of the steel cofferdam to support the steel cofferdam, and the inner support is installed inside the steel cofferdam to support it. The bottom plate steel pipe cage has a large-area foundation made of steel pipes to better provide stability for the inner and outer supports.

4. The method for constructing a complex deepwater environment compartment concrete reinforced steel cofferdam as claimed in claim 1, characterized in that: In step S5, the steel cofferdam is transported onto the ship using a flatbed truck.

5. The method for constructing a complex deepwater environment compartment concrete reinforced steel cofferdam as claimed in claim 1, characterized in that: In step S7, when pouring concrete in the compartment, the steel cofferdam is poured symmetrically at the center, first pouring the first section corner standard blocks, and then pouring the first section middle standard blocks.

6. The method for constructing a complex deepwater environment compartment concrete reinforced steel cofferdam as claimed in claim 1, characterized in that: In step S1, the outer walls of the first-section corner standard block and the first-section middle standard block are higher than the inner walls by a set height, and the outer walls of the non-first-section corner standard block and the non-first-section middle standard block are higher than the inner walls and the partition board by a set height.

7. The method for constructing a complex deepwater environment compartment concrete reinforced steel cofferdam as claimed in claim 6, characterized in that: In step S8 and step S1, the outer walls of the first-section corner standard blocks and the first-section middle standard blocks are 50 cm higher than the inner walls, and the outer walls of the non-first-section corner standard blocks and the non-first-section middle standard blocks are 50 cm higher than the inner walls and partition boards.

8. The method for constructing a complex deepwater environment compartment concrete reinforced steel cofferdam as claimed in any one of claims 1 to 7, characterized in that: In step S1, the bottoms of the first section corner standard block and the first section middle standard block are provided with cutting edges.

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