A composite cofferdam and its construction method

Abstract

This application relates to the field of bridge construction technology, and particularly to a combined cofferdam and its construction method. The combined cofferdam includes a steel casing, a caisson, internal supports, sheet piles, and a hoisting system. The steel casing is detachably equipped with a first temporary support structure and an assembly platform for assembling unit modules. The caisson includes multiple unit modules that are detachably connected. The internal supports are located inside the caisson, and a second temporary internal support is provided on the steel casing, with the internal supports erected on the second temporary internal support. Sheet piles are disposed between the caisson and the internal supports. The hoisting system is mounted on the steel casing and connected to the caisson for lifting and lowering the caisson. This application provides a construction method for a combined cofferdam to solve the problems of difficulty in lowering the entire steel cofferdam and its susceptibility to external conditions in related technologies.

Description

Technical Field

[0001] This application relates to the field of bridge construction technology, and in particular to a combined cofferdam and a construction method for the combined cofferdam. Background Technology

[0002] With the rapid development of my country's social economy, the demand for convenient transportation is increasing, and infrastructure projects are developing rapidly, including more and more bridge structures and underwater construction projects. To overcome the impact of harsh natural conditions and land constraints, the requirements for the quality and safety of cofferdam construction are becoming increasingly stringent.

[0003] Currently, underwater cofferdam construction technology requires the construction of an operating platform in the river channel, and then the steel cofferdam is assembled and lowered as a whole on the platform. Due to the large size and weight of the cofferdam, the requirements for the load-bearing capacity of the construction platform and the performance of the crane are high. Moreover, the operation is difficult and the lowering accuracy is hard to control. In addition, it is affected by harsh natural conditions and land use restrictions. Therefore, large and complex combined cofferdams and construction methods have become a research topic. Summary of the Invention

[0004] This application provides a combined cofferdam and a construction method for the combined cofferdam to solve the problems in related technologies, such as the difficulty in lowering the steel cofferdam as a whole and its susceptibility to external conditions.

[0005] Firstly, a combined cofferdam is provided, comprising:

[0006] The housing comprises multiple unit modules, which are detachably connected.

[0007] A steel casing, on which a first temporary support structure and an assembly platform for assembling unit modules are detachably provided, the first temporary support structure being connected to the steel casing, and the assembly platform being located on the first temporary support structure;

[0008] An inner support is located inside the casing, and a second temporary support structure is provided on the steel casing. The inner support is erected on the second temporary support structure.

[0009] Sheet piles are installed between the casing and the inner support;

[0010] A suspension system is installed on the steel casing and is connected to the housing for lifting and lowering the housing.

[0011] In some embodiments, the unit module includes a first module and a second module, and both sides of the first module and the second module are provided with connecting surfaces.

[0012] In some embodiments, the first module includes an outer wall panel and an inner wall panel, which are connected by a ring plate and are arranged perpendicular to the outer wall panel and the inner wall panel. The ring plate is provided with a suspension lug.

[0013] In some embodiments, the first module further includes a horizontal truss parallel to the plane of the ring plate and overlapping the ring plate;

[0014] Two adjacent horizontal trusses form a triangular structure with the inner or outer wall panel.

[0015] In some embodiments, the unit module includes a cutting foot that is positioned away from the suspension system and on the side away from the steel casing when the casing is lowered using a sling system.

[0016] In some embodiments, the inner support includes a first steel waler and a second steel waler arranged perpendicular to each other.

[0017] In some embodiments, the internal support further includes diagonal bracing, the two ends of which are respectively connected to two first steel walers perpendicular to each other.

[0018] Secondly, a construction method for a combined cofferdam is provided, which includes the following steps:

[0019] Provide a combined cofferdam as described in any of the above descriptions;

[0020] Insert the steel casing;

[0021] A first temporary support structure is set on the steel casing, and an assembly platform is built on the first temporary support structure;

[0022] Multiple unit modules are hoisted onto the assembly platform and then assembled into a complete set.

[0023] A hoisting system was installed at the top of the steel casing. The hoisting system was used to lift the casing and dismantle the first temporary support structure and assembly platform.

[0024] After the caisson is lowered into place using a hoisting system, the soil inside the caisson is excavated to lower the internal riverbed elevation to the first height.

[0025] Weld a second temporary support structure to the outside of the steel casing, and overlap a temporary inner support on the second temporary support structure;

[0026] Steel sheet piles were driven between the temporary internal support and the steel caisson to form a cofferdam;

[0027] Remove the second temporary support structure and the temporary inner support, use a hoisting system to lower the inner support, and make the inner support fit against the inner wall of the cofferdam;

[0028] Underwater concrete is poured to seal the bottom, and the water-stopping effect is checked. After the inspection is passed, construction is carried out on the inner side of the cofferdam.

[0029] After the bottom sealing concrete reaches the design strength, the casing will be removed.

[0030] In some embodiments, installing a suspension system at the top of the steel casing includes the following steps:

[0031] A distribution beam is installed at the top of the steel casing, and a Bailey bridge is erected on the distribution beam, with the Bailey bridge perpendicular to the distribution beam.

[0032] Determine the suspension point on the Bailey bridge corresponding to the suspension point of the housing, and set up a steel support, a drive device and a suspension rope at the suspension point. Set the drive device on the steel support, connect the suspension rope to the drive device, and connect one end of the suspension rope to the housing.

[0033] In some embodiments, when multiple unit modules are assembled into a box, a water-stop pad is provided on the contact surface of the unit modules, and adjacent unit modules are connected by bolts.

[0034] The beneficial effects of the technical solution provided in this application include:

[0035] This application provides a combined cofferdam and a construction method for the combined cofferdam. Since the cofferdam is divided into multiple unit modules and based on a steel casing, a first temporary support structure is set on the steel casing, and an assembly platform is built, the multiple unit modules are assembled into a cofferdam on the assembly platform. It is not necessary to transport the entire cofferdam to the riverbank and then transfer it to the hoisting point, thus saving the transportation steps. After the cofferdam is assembled, it is only necessary to lift the entire cofferdam after it is assembled, leaving space to dismantle the first temporary support structure and the assembly platform. After dismantling, it can be lowered.

[0036] After the casing is lowered to the designated position, a second temporary support structure is set up on the steel casing to build a temporary inner support. The temporary inner support acts as a guide device and together with the casing, forms the space for driving steel sheet piles. After the steel sheet piles are driven, a cofferdam is formed. Then, the inner support is lowered through the hoisting system to support the cofferdam.

[0037] After the construction of the structures inside the cofferdam is completed, the caisson and cofferdam are dismantled. At this time, the connection between the unit modules can be disconnected underwater and the modules can be lifted out in sections, which can reduce the pressure of lifting the caisson underwater. Therefore, it can solve the problems of the difficulty of lowering the steel cofferdam as a whole and the great influence of external conditions in related technologies. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 An elevation view of the completed sheet pile driving according to an embodiment of this application;

[0040] Figure 2 A plan view of the steel sheet piles after driving them into place, provided in an embodiment of this application;

[0041] Figure 3 for Figure 2 Enlarged view of point A in the middle;

[0042] Figure 4 A schematic diagram of the housing, the first module, and the second module provided in the embodiments of this application;

[0043] Figure 5 A plan view of the first module provided in an embodiment of this application;

[0044] Figure 6 The diagram shows a side cross-sectional view of the first module and the second module provided in the embodiments of this application.

[0045] In the diagram: 1. Steel casing; 2. Unit module; 21. Outer wall panel; 22. Inner wall panel; 23. Ring plate; 24. Horizontal truss; 25. Cutting foot; 251. Inner plate of cutting foot; 252. Cutting foot cladding plate; 26. Reinforcing plate; 27. Lifting lug; 28. Connecting surface; 3. Housing; 31. First module; 32. Second module; 4. Suspension system; 41. Distribution beam; 42. Bailey bridge; 43. Lifting rope; 44. Drive device; 5. Second temporary support structure; 6. Internal support; 61. First steel waler; 62. Second steel waler; 63. Diagonal brace; 7. Steel sheet pile. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0047] This application provides a combined cofferdam, which can solve the problems in related technologies such as the difficulty of lowering the entire steel cofferdam and its susceptibility to external conditions.

[0048] See Figures 1 to 6 As shown, this application provides a combined cofferdam, which includes a steel casing 1, a caisson 3, an internal support 6, steel sheet piles 7, and a suspension system 4. Specifically, it combines... Figure 1 and Figure 2 As shown, the steel casing 1 is driven into the riverbed, and the casing 3 includes multiple unit modules 2. The unit modules 2 can be lowered in sections by the hanging system 4 set on the steel casing 1. The multiple unit modules 2 are assembled into the casing 3 by the first temporary support structure on the steel casing 1, and the casing 3 is lowered by the hanging system 4.

[0049] Meanwhile, a second temporary support structure 5 is also provided on the steel casing 1. An inner support 6 is erected on the second temporary support structure 5. The inner support 6 is located inside the casing 3, and a positioning space for driving the steel sheet pile 7 is formed between the inner support 6 and the casing 3, which plays a positioning role in driving the steel sheet pile 7.

[0050] This application provides a combined cofferdam. Since the cofferdam 3 includes multiple unit modules 2 and is assisted by a steel casing 1, a first temporary support structure is set on the steel casing 1. That is, the hoisting system 4 is used to hoist each unit module 2 to a designated position and lower it to the first temporary support structure and assembly platform. The multiple unit modules 2 are then assembled into the cofferdam 3 on the first temporary support structure and assembly platform. It is not necessary to transport the entire cofferdam 3 to the riverbank and then transfer it to the hoisting point, thus saving the transportation steps. After the cofferdam 3 is assembled, it is only necessary to lift the cofferdam 3 as a whole to leave space for dismantling the first temporary support structure and assembly platform. After dismantling, it can be lowered.

[0051] After the casing 3 is lowered to the designated position, a second temporary support structure 5 is set on the steel casing 1 to build a temporary inner support 6. The temporary inner support 6 acts as a guide device and together with the casing 3, forms the space for driving the steel sheet piles 7. After the steel sheet piles 7 are driven, a cofferdam is formed. Then, the inner support is lowered through the hoisting system 4 to support the cofferdam. Therefore, it can solve the problems of the difficulty in lowering the steel cofferdam as a whole and the great influence of external conditions in related technologies.

[0052] In some embodiments, see Figure 4 and Figure 5 As shown, unit module 2 includes a first module 31 and a second module 32, and both sides of the first module 31 and the second module 32 are provided with connecting surfaces 28 for connecting the first module 31 and the second module 32 to each other.

[0053] Preferably, water-stop pads are provided at the connection surfaces 28 where the two modules connect to enhance the sealing of the housing 3;

[0054] Optionally, the connection between the two modules can be a bolt connection, with the water-stop pad held between the two adjacent modules;

[0055] It should be noted that the above-mentioned modules refer to either the first module 31 or the second module 32.

[0056] Specifically, Figure 4 This is a plan view showing the connection between the first module 31 and the second module 32 in this embodiment, including four first modules 31 with corners and two second modules 32 with straight edges. Figure 5 This is a plan view of the first module 31 given in this embodiment, which has two connecting surfaces 28; Figure 6 Lateral cross-sectional view of the first module 31 and the second module 32

[0057] In some alternative embodiments, see Figure 5 and Figure 6 As shown, taking the first module 31 as an example, combined with Figure 5 In the top view of the first module 31, the first module 31 includes an outer wall panel 21 and an inner wall panel 22 that are spaced apart. An annular plate 23 is provided between the outer wall panel 21 and the inner wall panel 22. The annular plate 23 is perpendicular to the outer wall panel 21 and the inner wall panel 22 and is connected between the two.

[0058] Specifically, the ring plate 23 connects the outer wall plate 21 and the inner wall plate 22 together on the one hand, and also serves as a reinforcing mechanism to enhance the overall strength of the first module 31 on the other hand; optionally, the ring plate 23 is welded to the outer wall plate 21 and the inner wall plate 22.

[0059] Optionally, combined Figure 6 In the side view of the first module 31, it can be seen that there are multiple ring plates 23, which are arranged vertically between the outer wall plate 21 and the inner wall plate 22 of the first module 31.

[0060] Optionally, combined Figure 5 As shown, the ring plate 23 is provided with lifting lugs 27 for suspending the suspension system 4.

[0061] In some alternative embodiments, see Figure 5 and Figure 6 As shown, the first module 31 also includes a horizontal truss 24, which is parallel to the plane where the ring plate 23 is located and overlaps the ring plate 23.

[0062] Specifically, in combination Figure 5 and Figure 6 As shown, there are multiple horizontal trusses 24, with one end of the horizontal truss 24 facing the outer wall panel 21 and the other end facing the inner wall panel 22. Two adjacent horizontal trusses 24 form a triangular structure with the inner wall panel 22 or the outer wall panel 21 to increase the stability of the first module 31.

[0063] Since the casing 3 is typically made of steel, it is susceptible to deformation due to water flow impact and soil compression. Therefore, a corresponding reinforcing plate 26 is installed. The reinforcing plate 26 enhances the cross-sectional parameters of the casing 3 structure, greatly improving the overall mechanical properties of its components and effectively resisting the impact of loads encountered during construction without deformation.

[0064] Optionally, combined Figure 5 As shown, the first module 31 also includes a reinforcing plate 26, which is evenly and spaced out on the opposite side of the outer wall panel 21 and the inner wall panel 22 to enhance the strength of the entire first module 31.

[0065] Specifically, the upper and lower ends of the outer wall panel 21 and the inner wall panel 22 are folded towards each other to form a folded surface, and the reinforcing plate 26 is disposed between the outer wall panel 21 or the inner wall panel 22 and the ring plate 23. Preferably, since there are multiple ring plates 23, which are arranged vertically between the outer wall panel 21 and the inner wall panel 22 along the first module 31, the reinforcing plate 26 can also be disposed between two adjacent ring plates 23.

[0066] In some alternative embodiments, see Figure 1 and Figure 6 As shown, unit module 2 includes a cutting edge 25, which can be specifically combined with... Figure 1 As shown, when the sling system 4 is used to lower the casing 3, the cutting edge 25 on the casing 3 is located at the end away from the sling system 4, and the inclined side of the cutting edge 25 is set towards the side of the steel casing 1 to enhance the force of the casing 3 sinking and inserting into the riverbed.

[0067] Optionally, combined Figure 6 As shown, a cutting edge plate 252 is provided at the cutting edge 25. The cutting edge plate covers the surface of the cutting edge 25 that is used to insert into the riverbed, which protects the cutting edge 25 and enhances its strength.

[0068] Optionally, combined Figure 6 As shown, the cutting edge 25 also includes a cutting edge inner plate 251, which is arranged parallel to the horizontal ring plate 23, and as shown in the figure. Figure 6 The setting shown is located near the tip of the cutting foot 25 to support the cutting foot 25 and also enhance the strength of the cutting foot 25.

[0069] In some alternative embodiments, see Figure 1 As shown, the suspension system 4 includes a distribution beam 41, a Bailey bridge 42, a drive device 44, and a suspension rope 43. Specifically, the distribution beam 41 is arranged perpendicularly to the Bailey bridge 42. The distribution beam 41 is erected on the top of the steel casing 1, and the Bailey bridge 42 is stacked vertically on the distribution beam 41.

[0070] Specifically, the steel casing 1 has multiple components, combined with... Figure 2 As shown, multiple steel casings 1 are arranged in a square array. Each steel casing 1 is equipped with a distribution beam 41, and these distribution beams 41 are arranged in parallel. The Bailey bridge 42 is set perpendicular to the distribution beams 41 on these distribution beams 41. The distribution beams 41 can connect two independent support points, ensuring that the force transmitted from the upper structure can be divided into two, so that the support point itself can meet the stress requirements.

[0071] Preferably, the distribution beam 41 is made of materials such as I-beams or H-beams, which have stable cross-sectional properties and a large load-bearing capacity.

[0072] Furthermore, the drive device 44 is mounted on the Bailey bridge 42, and the hoisting rope 43 is connected to the drive device 44 and driven by the drive device 44 to realize the upward and downward movement of the housing 3; optionally, the drive device 44 uses a hydraulic jack, and the hoisting rope 43 uses precision rolled threaded steel.

[0073] Furthermore, a steel support is provided at the position where the drive device 44 is located on the Bailey bridge 42. The drive device 44 is fixed to the Bailey bridge 42 by the steel support, which can prevent the drive device 44 from sliding under the tension of the suspension rope 43.

[0074] In some alternative embodiments, see Figures 1 to 3 As shown, the temporary internal support 6 includes a first steel waler 61 and a second steel waler 62 arranged perpendicularly to each other. Combined with... Figure 2 As shown, taking four steel casings 1 as an example, the second temporary support structure 5 is set on the outside of the steel casing 1. There are four first steel walers 61, which are perpendicular to each other to form a rectangle and are erected on the second temporary support structure 5 to provide internal support for the walers formed by the sheet piles 7. The second steel walers 62 are set parallel to two of the first steel walers 61 that are parallel to each other. Specifically, in combination with Figure 2 As shown, the second steel waler 62 is erected on the other two first steel walers 61 to provide better support for the Bailey bridge 42. The second steel waler 62 is erected on the second temporary support structure 5 to form a square structure to provide internal support for the waler formed by the sheet piles 7.

[0075] Optionally, combined Figure 2 and Figure 3 As shown, the temporary internal support 6 also includes diagonal braces 63, with both ends of the diagonal braces 63 connected to two mutually perpendicular first steel walers 61, in combination with... Figure 2 and Figure 3 As shown, the diagonal brace 63 and the two first steel walers 61 form a triangular structure. One end is connected to the first steel waler 61, and the other end is connected to the second steel waler 62. This structure can enhance the overall structural load-bearing capacity of the temporary internal support 6 and ensure its stability.

[0076] Optionally, the second temporary support structure 5 uses corbels.

[0077] See Figures 1 to 6 As shown, this application also provides a construction method for a combined cofferdam, including the following steps:

[0078] S1: Insert steel casing 1.

[0079] S2: Set up a first temporary support structure on the steel casing 1, and build an assembly platform on the first temporary support structure.

[0080] S3: Hoist multiple unit modules 2 onto the assembly platform and assemble the multiple unit modules 2 into a set box 3.

[0081] Specifically, when unit module 2 is hoisted onto the assembly platform, unit module 2 is positioned above the location of the housing 3. This way, during the subsequent lowering of housing 3, only the position of housing 3 needs to be adjusted.

[0082] S4: Install a hanging system 4 at the top of the steel casing 1, use the hanging system 4 to lift the casing 3, and dismantle the first temporary support structure and assembly platform.

[0083] Specifically, the assembly platform is located on the lowering path of the container 3, so the container 3 needs to be lifted first to remove it from the assembly platform, so as to facilitate the dismantling of the assembly platform and the lowering of the container 3.

[0084] S5: After lowering the casing 3 into place using the hoisting system 4, excavate the soil inside the casing 3 to lower the internal riverbed elevation to the first height.

[0085] Specifically, in combination Figure 1 As shown, the soil inside the casing 3 is excavated, so that the original riverbed surface inside the casing 3 is lowered to the excavated riverbed surface. This first height can be taken as 2.5m.

[0086] Specifically, after the three-pack is assembled, it forms an internal compartment;

[0087] Specifically, when lowering the casing 3 into the water, if the casing 3 floats on its own or lacks sufficient sinking force during the sinking process, water can be injected into the compartment to increase the self-weight of the casing 3. When sinking to the riverbed, if resistance is encountered and the sinking force is still insufficient after water injection, a long-arm excavator, grab bucket, or sludge suction machine can be used to remove the obstructing soil layer at the bottom of the casing 3, allowing the casing 3 to sink. It should be noted that during the lowering process, the lowering position needs to be measured and corrected in a timely manner, and each point should be lowered slowly and synchronously to the design elevation. After the casing 3 is placed in place, the soil inside the steel casing cofferdam should be cleared and excavated using a long-arm excavator, grab bucket, or sludge suction machine to lower the riverbed.

[0088] S6: Weld a second temporary support structure 5 to the outside of the steel casing 1, and attach a temporary inner support to the second temporary support structure 5;

[0089] Specifically, the temporary internal support is located inside the casing 3 and forms a limiting space between it and the inner wall of the casing 3, which facilitates the installation of the sheet piles 7.

[0090] S7: Drive steel sheet piles 7 between the temporary inner support and the steel casing 3 to form a cofferdam;

[0091] Optionally, sheet pile 7 may be a U-shaped cold-formed sheet pile.

[0092] Specifically, the sheet pile 7 is driven from the upstream corner, using a robotic pile driver or vibratory pile hammer for clamping: the sheet pile 7 is slowly lifted, and when the tip of the sheet pile 7 is 30cm off the ground, the lifting is stopped, the equipment arm is rotated, the sheet pile 7 is moved to the driving location, the angle of the sheet pile 7 is adjusted and the sheet pile 7 is moved, and the planar position of the sheet pile 7 is referenced to the outer side of the temporary inner support for driving the sheet pile 7.

[0093] First, drive the sheet piles freely, then use a robotic pile driver or vibratory hammer to apply force. During the pile driving process, the robotic arm should always clamp the sheet pile head 7 tightly, and gradually drive the sheet pile 7 in. Continuously observe the clamping condition of the sheet pile head 7 during driving. If loosening occurs, stop driving and re-clamp the sheet pile 7 with the hydraulic clamp. During the pile driving process, it is advisable to use measuring instruments to control the verticality of the sheet pile within 0.5%. If it exceeds the requirement, a winch should be used to correct the deviation in time; otherwise, it should be pulled out and re-driven. The pile driving speed should be slow, and deviations should be corrected at any time. When the sheet pile 7 is driven to 40cm before the design elevation, the measurement work at the top of the pile should be strengthened, and the driving speed should be slowed down to drive the pile to the design elevation (the top of the sheet pile 7) to prevent over-driving, until the sheet pile 7 is successfully closed. During the driving process, the construction key points of "straight driving, correction when dispersed, and adjustment for closure" must be followed.

[0094] S8: Remove the second temporary support structure 5 and the temporary inner support, use the hoisting system 4 to lower the inner support 6, and make the inner support 6 fit against the inner wall of the cofferdam;

[0095] Specifically, the six pairs of internal supports provide support to the inner walls of the pre-inserted cofferdam.

[0096] S9: Underwater concrete is poured to seal the bottom, and the water-stopping effect is checked. After the inspection is passed, construction is carried out on the inside of the cofferdam.

[0097] S10: After the bottom sealing concrete reaches the design strength, remove the casing 3;

[0098] Specifically, by disassembling the housing 3 underwater into multiple unit modules 2, and then lifting each unit module 2 out of the water, the pressure on the housing 3 when lifting it from underwater can be reduced.

[0099] This application provides a construction method for a combined cofferdam. Since the cofferdam 3 is divided into multiple unit modules 2, and a first temporary support structure is set on the steel casing 1 as the base, and an assembly platform is built, the multiple unit modules 2 are assembled into the cofferdam 3 on the assembly platform. It is not necessary to transport the entire cofferdam 3 to the riverbank and then transfer it to the hoisting point, thus saving the transportation steps. After the cofferdam 3 is assembled, it is only necessary to lift the cofferdam 3 as a whole, leaving space to dismantle the first temporary support structure and the assembly platform. After dismantling, it can be lowered.

[0100] After the casing 3 is lowered to the designated position, a second temporary support structure 5 is set on the steel casing 1 to build a temporary inner support. The temporary inner support acts as a guide device and together with the casing 3, forms the space for driving the steel sheet piles 7. After the steel sheet piles 7 are driven, a cofferdam is formed. Then, the inner support 6 is lowered through the hoisting system 4 to support the cofferdam.

[0101] After the construction of the structures inside the cofferdam is completed, the casing 3 and the cofferdam are dismantled. At this time, the connection between the unit modules 2 is disconnected underwater and the modules are lifted out in sections. This can reduce the pressure of lifting the casing 3 underwater. Therefore, it can solve the problems of the difficulty of lowering the steel cofferdam as a whole and the great influence of external conditions in related technologies.

[0102] In some alternative embodiments, see Figures 4 to 6 As shown, unit module 2 includes a first module 31 and a second module 32, wherein the first module 31 is a bent section and the second module 32 is a straight section. Multiple modules are selected and spliced ​​together to form a box 3 according to the required size of the cofferdam.

[0103] Specifically, installing the suspension system 4 at the top of the steel casing 1 includes the following steps:

[0104] A distribution beam 41 is set at the top of the steel casing 1, and a Bailey bridge 42 is erected on the distribution beam 41, with the Bailey bridge 42 set perpendicular to the distribution beam 41.

[0105] A suspension point is determined on the Bailey frame 42 corresponding to the suspension point of the housing 3. A steel support, a drive device 44, and a suspension rope 43 are installed at the suspension point. The drive device 44 is installed on the steel support, the suspension rope 43 is connected to the drive device 44, and one end of the suspension rope 43 is connected to the housing 3.

[0106] It should be noted that, in order to avoid interference between the hanging system 4 of the hanging casing 3 and the sheet pile 7 during the driving of the sheet pile 7, the original affected hanging points can be transferred by replacing the hanging points. That is, a bracket is welded on the corresponding steel casing 1, and the hanging point is transferred to the corresponding position of the bracket and the casing 3. After the affected sheet pile 7 is driven, the hanging point is reset to the original position.

[0107] Optionally, the suspension system 4 can be divided into a casing suspension system and an internal support suspension system. The casing suspension system is used to suspend the casing 3, and the internal support suspension system is used to suspend the internal support 6.

[0108] Optionally, the inner support 6 includes a first inner support and a second inner support. The first inner support is first lowered to the design elevation using an inner support suspension system, and then the second inner support is lowered to the design elevation. The first inner support is located below the second inner support.

[0109] In S10 above, after the bottom sealing concrete reaches the design strength, the casing 3 is removed and the hanging system 4 is dismantled. Specifically, the casing 3 is unbolted underwater and lifted away in sections.

[0110] When removing the bolts, maintain the water pressure balance inside and outside the cofferdam. Start from the downstream and remove the bolts on the side plates along the vertical joint. Use a 75t crawler crane to lift the sections away from the pier. Ensure that the demolition work is carried out during low tide. Before lifting, take measures to stabilize the side plates near the demolition section.

[0111] After the bottom sealing concrete reaches its design strength, the second inner support and walers are removed, and the foundation construction begins. Once the pier body is above water, water is injected into the cofferdam to equalize the water head inside and outside. After removing the first inner support and walers, sheet piles 7 are extracted using a robotic pile driver or vibratory pile hammer. The removal of sheet piles 7 from the cofferdam should be carried out in reverse order of the cofferdam construction, starting downstream and proceeding symmetrically upstream.

[0112] Specifically, the method for removing sheet piles is as follows: First, use a robotic pile driver or vibratory hammer to clamp the head of the sheet pile 7 and vibrate it for 1-2 minutes to loosen the soil around the sheet pile 7, causing it to "liquefy" and reducing the frictional resistance between the soil and the pile. Then, slowly pull it upwards. During extraction, pay attention to the load on the pile driver. If it becomes difficult to pull the pile upwards or it cannot be pulled out, stop extraction. You can first drive the pile downwards a little, then pull it upwards again. Repeat this process until the pile is removed. For sheet piles with rolled tips or deformed interlocking joints, increase the extraction capacity and pull them out simultaneously with adjacent piles.

[0113] This application provides a construction method for a combined cofferdam, which has the following advantages:

[0114] (1) Using the casing 3 and temporary internal support as a guide frame for the construction of sheet pile 7 improves the accuracy of the construction of sheet pile 7;

[0115] (2) The sheet piles 7 form the walers and rely on the internal supports to support the inner wall, providing ample operating space for the excavation of the riverbed surface;

[0116] (3) In the housing 3, the joint of the unit module 2 is filled with a water-stop pad to avoid underwater installation of water-stop cloth.

[0117] (4) The construction is simple. The assembly of the 3-box is completed on the assembly platform, which reduces the underwater installation and dismantling operations and is conducive to dismantling and reuse.

[0118] (5) It has a smaller impact on the environment and is particularly suitable for the construction of underwater structures under environmental constraints and complex conditions, which can shorten the construction period, reduce the construction difficulty, and improve the construction safety factor.

[0119] In the description of this application, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0120] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0121] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A modular cofferdam, characterized in that, It comprises: a casing box (3) comprising a plurality of unit modules (2) which are detachably connected; a steel casing (1) on which a first temporary support structure for assembling the unit modules (2) and an assembling platform are detachably arranged, the first temporary support structure is connected with the steel casing (1), and the assembling platform is located on the first temporary support structure; an inner support (6) located inside the casing box (3), the steel casing (1) is provided with a second temporary support structure (5), and the inner support (6) is arranged on the second temporary support structure (5); a steel sheet pile (7) arranged between the casing box (3) and the inner support (6); a hanging system (4) arranged on the steel casing (1), the hanging system (4) is connected with the casing box (3) and used for lifting and lowering the casing box (3); wherein the unit module (2) comprises a first module (31) and a second module (32), and the two sides of the first module (31) and the second module (32) are provided with connecting surfaces (28); a water stop pad is arranged at the connecting surface (28); and the inner support (6) comprises first steel enclosing purlins (61) and second steel enclosing purlins (62) which are arranged perpendicular to each other.

2. The combined cofferdam according to claim 1, characterized in that: the first module (31) comprises an outer wall plate (21) and an inner wall plate (22), the outer wall plate (21) and the inner wall plate (22) are connected through a ring plate (23), the ring plate (23) is arranged perpendicular to the outer wall plate (21) and the inner wall plate (22), and a lifting lug (27) for suspension is arranged on the ring plate (23).

3. The combined cofferdam according to claim 2, characterized in that: the first module (31) further comprises horizontal trusses (24), the horizontal trusses (24) are parallel to the plane in which the ring plate (23) is arranged, and are arranged on the ring plate (23); two adjacent horizontal trusses (24) and the inner wall plate (22) or the outer wall plate (21) form a triangular structure.

4. The combined cofferdam according to claim 1, characterized in that: the unit module (2) comprises a blade foot (25), when the casing box (3) is lowered by using the hanging system (4), the blade foot (25) is away from the hanging system (4) and is arranged on the side away from the steel casing (1).

5. The combined cofferdam according to claim 1, characterized in that: the inner support (6) further comprises diagonal braces (63), the two ends of the diagonal braces (63) are connected with two first steel enclosing purlins (61) which are perpendicular to each other.

6. A method of constructing a composite cofferdam, characterised in that, It comprises the following steps: providing a combined cofferdam according to any one of claims 1-5; driving a steel casing (1); arranging a first temporary support structure on the steel casing (1) and building an assembling platform on the first temporary support structure; hoisting a plurality of unit modules (2) to the assembling platform and assembling the plurality of unit modules (2) into a casing box (3); arranging a hanging system (4) at the top end of the steel casing (1), lifting the casing box (3) by using the hanging system (4), and removing the first temporary support structure and the assembling platform; After the casing (3) is lowered into position using the hanging system (4), the soil in the casing (3) is excavated to lower the internal riverbed elevation to a first height; A second temporary support structure (5) is welded outside the steel casing (1), and a temporary inner support is lapped on the second temporary support structure (5); Steel sheet piles (7) are inserted between the temporary inner support and the casing (3) to form a cofferdam; The second temporary support structure (5) and the temporary inner support are removed, the inner support (6) is lowered using the hanging system (4), and the inner support (6) is fitted to the inner wall of the cofferdam; Underwater concrete pouring is performed to seal the bottom, the water sealing effect is checked, and construction is performed on the inner side of the cofferdam after the check is passed; After the sealing concrete reaches the design strength, the casing (3) is removed.

7. The method of constructing a composite cofferdam of claim 6, wherein, Setting the hanging system (4) at the top end of the steel casing (1) includes the following steps: A distribution beam (41) is set at the top end of the steel casing (1), and a Bailey frame (42) is erected on the distribution beam (41), and the Bailey frame (42) is arranged vertically to the distribution beam (41); Suspension points are determined on the Bailey frame (42) corresponding to the suspension of the casing (3), and profile steel supports, drive devices (44) and lifting ropes (43) are arranged at the suspension points, and the drive devices (44) are arranged on the profile steel supports, the lifting ropes (43) are connected with the drive devices (44), and one end of the lifting ropes (43) is connected with the casing (3).

8. The construction method of the combined cofferdam according to claim 6, characterized in that: When the plurality of unit modules (2) are assembled into the casing (3), a water stop pad is arranged at the abutting surface of the unit module (2), and adjacent unit modules (2) are connected by bolts.

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