Cofferdam lowering and pile cap pouring construction method and cofferdam lowering construction device

Abstract

The application discloses a cofferdam lowering and pile cap pouring construction method and a cofferdam lowering construction device. The construction method comprises the following steps: monitoring the real-time tide level of the water area where the cofferdam is located; when the monitored tide level is smaller than a preset tide level, installing a cofferdam assembling platform, assembling the cofferdam on the cofferdam assembling platform, and assembling a bottom compartment at the bottom of the cofferdam; opening the inner-outer communication hole and the inner wall communication hole; when the monitored tide level is greater than the preset tide level, lowering the cofferdam to a self-floating state of the cofferdam through a hoisting system; when the monitored tide level is smaller than the preset tide level, lowering the cofferdam to a preset position by using the scouring force generated under the condition of the reciprocating flow flow rate of the large water area and through the hoisting system; performing bottom sealing construction at the bottom of the cofferdam; after the bottom sealing concrete reaches a preset strength, closing the inner-outer communication hole, opening the inner wall communication hole, pumping out the water in the cofferdam, and pouring the pile cap. The application can reduce the construction cost and improve the construction stability of the cofferdam lowering and pile cap pouring.

Description

Technical Field

[0001] This invention relates to the field of bridge substructure construction technology, specifically to a method and device for cofferdam lowering and pier cap pouring. Background Technology

[0002] With the development of rapid bridge construction technology, a common construction method in existing pile-cap underwater foundation construction technology is to use a double-walled cofferdam to complete the underwater foundation construction. For buried foundation construction, the common approach is to use dredging equipment to assist in the simultaneous dredging and water injection after the cofferdam is in place. However, this method requires a large number of dredging devices and has low construction efficiency. When constructing cofferdams in areas with strong tidal bores, the large tidal range that occurs within a certain time period each day will significantly affect the buoyancy of the cofferdam, thus affecting its attitude. Furthermore, in strong tidal environments, the scouring of the cofferdam after it enters the water will be more intense, making it difficult to guarantee the constraint of the seabed base after the cofferdam has sunk to its final position. Summary of the Invention

[0003] This application provides a method and device for cofferdam lowering and foundation pouring, which can solve the technical problem of difficult cofferdam construction in strong tidal zone environments in the prior art.

[0004] In a first aspect, embodiments of this application provide a method for cofferdam lowering and foundation casting, used to achieve cofferdam lowering and foundation casting in water conditions with large semi-diurnal tidal range and high reciprocating flow velocity, including: Monitor the real-time tide level of the waters where the cofferdam is located; When the monitored tide level is lower than the preset tide level, a cofferdam assembly platform is installed, the cofferdam is assembled on the cofferdam assembly platform, and the bottom compartment is assembled at the bottom of the cofferdam. Open the inner and outer connecting holes set on the inner wall of the cofferdam, the inner and outer connecting holes on the outer wall of the cofferdam, and the inner wall connecting hole on the inner wall of the cofferdam. When the monitored tide level is higher than the preset tide level, the cofferdam is lowered to the self-floating state through the hoisting system. Water is injected between the inner and outer walls. When the monitored tide level is lower than the preset tide level, the cofferdam is lowered to the preset position by utilizing the scouring force generated under the conditions of a large water body with reciprocating flow velocity and through the hanging system. The bottom sealing construction is carried out at the bottom of the cofferdam. After the bottom sealing concrete reaches the preset strength, the inner and outer connecting holes are closed, the inner wall connecting holes are opened, the water in the cofferdam is pumped out, and the foundation is poured.

[0005] In conjunction with the first aspect, in one embodiment, the cofferdam includes an inner wall and an outer wall. The step of installing a cofferdam assembly platform when the monitored tide level is lower than a preset tide level, assembling the cofferdam on the cofferdam assembly platform, and assembling the bottom compartment at the bottom of the cofferdam includes: The steel casing located inside the cofferdam and at the lowering point of the cofferdam is raised to a first preset height, and the steel casing located inside the cofferdam but not at the lowering point of the cofferdam is raised to a second preset height. A connecting system is installed between multiple steel casings located inside the cofferdam. When the monitored tide level is lower than the preset tide level, a cofferdam assembly platform is welded to the outer wall of the steel casing located inside the cofferdam and at the lowering point of the cofferdam. The cofferdam is assembled sequentially on the cofferdam assembly platform, and the bottom compartment is assembled at the bottom of the cofferdam. A cutting edge is provided at the bottom edge of the cofferdam. Multiple guide structures are installed on the inner wall of the cofferdam, wherein one end of each guide structure is fixedly connected to the inner wall, and the other end of each guide structure abuts against the steel casing. Pour concrete for the bottom compartment and the cutting edge.

[0006] In conjunction with the first aspect, in one embodiment, after pouring the bottom compartment concrete and the cutting edge concrete, the method further includes: Monitor the seabed scour depth in the waters where the cofferdam is located, and when the monitored seabed scour depth is greater than the preset depth, dump ton bags around the cutting edge.

[0007] In conjunction with the first aspect, in one embodiment, lowering the cofferdam to a self-floating state via a hoisting system specifically includes: Install a hanging system at the top of the steel casing located inside the cofferdam and at the lowering point of the cofferdam; The cofferdam is lifted to a position detached from the cofferdam assembly platform using the hoisting system, and the cofferdam assembly platform is then dismantled. The cofferdam was adjusted to a vertical position using a guide structure. The cofferdam is lowered to a self-floating state using the hoisting system.

[0008] In conjunction with the first aspect, in one embodiment, closing the inner and outer connecting holes, opening the inner wall connecting hole, pumping out the water inside the cofferdam and the water between the inner and outer walls, and pouring the foundation, specifically includes: Close the inner and outer connecting holes, open the inner wall connecting holes, and pump out the water inside the cofferdam as well as the water between the inner and outer walls. Unload the suspension system, cut off the steel casing, and dismantle the guide structure; The foundation is cast, wherein the foundation includes a first foundation and a second foundation, and the first foundation and the second foundation are cast sequentially.

[0009] In conjunction with the first aspect, in one embodiment, prior to the sealing construction at the bottom of the cofferdam, the following steps are also included: Control the suspension system to a taut state; Continue injecting water between the inner wall and the outer wall until the distance between the water surface between the inner wall and the outer wall and the top of the cofferdam reaches a preset distance; Record the elevation changes of the cofferdam. When the elevation changes of the cofferdam do not exceed the preset rate of change, carry out the bottom sealing construction.

[0010] Secondly, this application provides a cofferdam lowering construction device. The cofferdam includes an inner wall and an outer wall, and multiple steel casings are located inside the cofferdam. The device includes: a hoisting system for controlling the lowering of the cofferdam, one end of which is fixed to the top of the steel casing, and the other end of which is fixed to the cofferdam; and multiple guide structures for fixing to the inner wall of the cofferdam, one end of each guide structure being fixedly connected to the inner wall, and the other end of each guide structure abutting against the steel casing.

[0011] In conjunction with the second aspect, in one embodiment, the suspension system includes: a suspension beam fixed to the top of a steel casing adjacent to the cofferdam; and a lower anchor beam connected to the suspension beam by a sling and fixed to the cofferdam.

[0012] In conjunction with the second aspect, in one embodiment, the guide structure includes: a base, the base being fixedly connected to the inner wall of the cofferdam; a telescopic drive member, the telescopic drive member being telescopically connected to the side of the base away from the cofferdam; and a guide member, one end of the guide member abutting against the steel casing, and the other end of the guide member being fixedly connected to the telescopic drive member.

[0013] In conjunction with the second aspect, in one embodiment, the guide element is a guide wheel.

[0014] The beneficial effects of the technical solutions provided in this application include: (1) In this embodiment of the application, the bottom compartment is assembled at the bottom of the cofferdam, and the scouring force generated under the condition of high reciprocating flow velocity in the water area is used to lower the cofferdam to the preset position through the hoisting system. The tidal surge effect is effectively utilized to improve the water flow field at the bottom of the cofferdam, so that the bottom cover layer of the cofferdam is scoured more evenly, which makes it easier to lower the cofferdam into place. Then, the cofferdam is continuously hoisted to the vicinity of the top of the scoured seabed through the hoisting system. The cofferdam can be continuously lowered to the design position while being scoured, and the cofferdam is prevented from sinking further.

[0015] (2) The embodiments of this application can achieve water level balance between the three parties, namely, the area outside the cofferdam, the inner and outer walls of the cofferdam, and the area within the cofferdam, by setting the inner and outer connecting holes and the inner wall connecting holes. This can ensure that the buoyancy of the cofferdam in the strong tidal water area is not affected by the tide level, thereby ensuring the vertical attitude of the cofferdam.

[0016] (3) In this embodiment of the application, the tide level of the water area where the cofferdam is located is measured, and when the tide level measured again is less than the preset tide level, the cofferdam is lowered to the preset position by the hoisting system. When the tide level measured again is less than the preset tide level, it means that the water area where the cofferdam is located is in the slack tide period. By choosing the slack tide period, the cofferdam can be quickly placed on the bed, thereby reducing the use of sludge suction equipment, simplifying the construction process, and improving the construction efficiency.

[0017] (4) The embodiments of this application utilize a hanging system, which not only achieves the purpose of scouring and sinking of the cofferdam, but also effectively protects the cofferdam from further sinking after it has sunk to the designated position, thereby improving the safety factor of the cofferdam. Attached Figure Description

[0018] 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.

[0019] Figure 1 A flowchart illustrating the cofferdam lowering and foundation pouring construction method provided in this application embodiment; Figure 2 This is a front view of the cofferdam after it has been lowered, as provided in an embodiment of this application. Figure 3 This is a side view of the cofferdam after it has been lowered, as provided in an embodiment of this application. Figure 4 This is a top view of the cofferdam after it has been lowered, provided in an embodiment of this application. Figure 5 This is a schematic diagram of the hanging system and guide structure provided in the embodiments of this application.

[0020] In the diagram: 1. Cofferdam; 2. Bottom compartment; 3. Suspension system; 301. Suspension beam; 302. Suspension cable; 303. Lower anchor beam; 4. Steel casing; 501. Internal and external connecting hole; 502. Internal wall connecting hole; 6. Guide structure; 7. Internal support. Detailed Implementation

[0021] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0022] This application provides a method and device for cofferdam lowering and foundation pouring, which can solve the technical problem of difficult cofferdam construction in strong tidal zone environments in the prior art.

[0023] Figure 1 A flowchart illustrating the cofferdam lowering and foundation casting construction method provided in this application embodiment. Figure 1 As shown in the figure, this application provides a method for cofferdam lowering and foundation pouring construction, including: Step S1: Monitor the real-time tide level of the water area where the cofferdam is located.

[0024] Specifically, the waters where the cofferdam is located have large semi-diurnal tidal ranges. By monitoring the real-time tide level of the waters where the cofferdam is located, the time windows for key operations in the overall construction process can be determined, turning the twice-daily tidal cycles into predictable construction cycles. This improves work efficiency, reduces reliance on large equipment, and thus significantly reduces construction costs and time.

[0025] Step S2: When the monitored tide level is lower than the preset tide level, install the cofferdam assembly platform, assemble the cofferdam on the cofferdam assembly platform, and assemble the bottom compartment at the bottom of the cofferdam.

[0026] Specifically, when the monitored tide level is lower than the preset tide level, it means that the tide is low or close to the low tide. At this time, the water flow is the slowest and the water level is the lowest, which is the most suitable for work that requires a relatively stable environment and precise operation by personnel, such as installing and assembling platforms and cofferdams.

[0027] In this embodiment of the application, step S2 specifically includes the following steps: Step S21: Raise the steel casing 4 located inside the cofferdam 1 and at the lowering point of the cofferdam 1 to a first preset height, raise the steel casing 4 located inside the cofferdam 1 but not at the lowering point of the cofferdam 1 to a second preset height, and install a connecting system between the multiple steel casings 4 located inside the cofferdam 1.

[0028] In the overall construction process of pile foundation construction within cofferdam 1, after the bored pile construction is completed, the drilling platform structure within the cofferdam 1 area is dismantled, while the surrounding support trestle bridge is retained. In a specific embodiment, the steel casing 4 located within cofferdam 1 and at the lowering point of cofferdam 1 is raised to a first preset height of 27.6 m, and the steel casing 4 located within cofferdam 1 but not at the lowering point of cofferdam 1 is raised to a second preset height of 20.0 m.

[0029] Step S22: When the monitored tide level is lower than the preset tide level, weld the cofferdam 1 assembly platform to the outer wall of the steel casing 4 located inside the cofferdam 1 and at the lowering point of the cofferdam 1.

[0030] When the measured current tide level is lower than the preset tide level, it means that the water area where the cofferdam 1 is located is at a low tide. At a low tide, the water level is lower and the water depth in the construction area is shallower, which provides more operating space for welding and assembly work. At the same time, the water flow is relatively stable at a low tide, and the construction environment is relatively stable, which reduces the impact of water flow on construction personnel and equipment and improves construction safety.

[0031] Step S23: Assemble the cofferdam 1 sequentially on the cofferdam 1 assembly platform, and assemble the bottom compartment 2 at the bottom of the cofferdam 1. Cutting feet are provided at the bottom edge of the cofferdam 1.

[0032] The cofferdam 1 was manufactured in sections at the factory, which facilitated subsequent transportation and hoisting before being shipped to the pier. On-site, temporary struts were installed between the inner wall of the cofferdam 1 and the extended steel casing 4 to provide additional support for the side plates of the cofferdam 1 and enhance the overall stability of the cofferdam 1 during assembly.

[0033] Figure 4 This is a top view of the cofferdam after it has been lowered, as provided in an embodiment of this application. See also... Figure 4 Temporary outriggers are installed on some of the steel casings 4 for auxiliary support, thereby installing the bottom compartment 2. By assembling the bottom compartment 2 at the bottom of the cofferdam 1, the water flow field at the bottom of the cofferdam 1 can be changed by utilizing the tidal surge effect, making the scouring of the bottom cover layer of the cofferdam 1 more uniform and facilitating the lowering of the cofferdam 1 into place. The bottom compartment 2 in this application includes two longitudinal bottom compartments 2. The setting of the bottom compartment 2 can achieve uniform scouring of the cover layer, avoid severe local scouring that leads to uneven settlement of the cofferdam 1, make the cofferdam 1 more uniformly stressed, and enhance the stability of the cofferdam 1.

[0034] Step S24: Install multiple guide structures 6 on the inner wall of the cofferdam 1, wherein one end of any guide structure 6 is fixedly connected to the inner wall, and the other end of any guide structure 6 abuts against the steel casing 4.

[0035] In areas with strong tidal surges, the tidal flow velocity is high, and the lateral impact force of the water flow on the cofferdam 1 is strong, which can easily cause the cofferdam 1 to undergo horizontal displacement or tilting during the sinking process. In this embodiment of the application, the setting of the guide structure 6 can effectively guide the cofferdam 1 to maintain a stable vertical posture during the sinking process. Specifically, multiple guide structures 6 can be set at different heights in the vertical direction of the cofferdam 1, and multiple guide structures 6 can be set on the same horizontal plane according to the actual shape or size of the cofferdam 1, which is not limited here.

[0036] Specifically, Figure 2 This is a front view of the cofferdam after it has been lowered, as provided in an embodiment of this application. See also... Figure 2Simultaneously with the installation of the guide structure 6, the bottom inner support 7 is installed. The bottom inner support 7 can effectively resist the pressure on the cofferdam 1 during the sinking process, preventing the cofferdam 1 from deforming or becoming unstable. After the cofferdam 1 is assembled, kerosene is applied to the joints and other locations of the cofferdam 1, and the penetration of the kerosene is observed. A kerosene permeability test is conducted to ensure that the sealing of the cofferdam 1 meets the design requirements.

[0037] Step S25: Pour concrete for the bottom compartment 2 and the cutting edge.

[0038] In this embodiment of the application, after pouring the concrete for the bottom compartment 2 and the cutting edge concrete, the method further includes: monitoring the seabed scour depth of the water area where the cofferdam 1 is located, and when the monitored seabed scour depth is greater than a preset depth, dumping ton bags around the cutting edge.

[0039] Specifically, the preset depth should be a depth that ensures the cofferdam 1 will not lose stability due to excessive scouring during the sinking process. This depth needs to be set according to the actual site conditions and is not limited here. Furthermore, the protective layer formed by the ton bags can increase the stability around the cutting edge of the cofferdam 1 and reduce the displacement and tilting of the cofferdam 1 caused by scouring during the sinking process.

[0040] Step S3: Open the inner and outer connecting holes 501 on the inner wall of the cofferdam 1, the inner and outer connecting holes 501 on the outer wall of the cofferdam 1, and the inner wall connecting hole 502 on the inner wall of the cofferdam. When the monitored tide level is greater than the preset tide level, the cofferdam 1 is lowered to the self-floating state of the cofferdam 1 through the hanging system 3.

[0041] The embodiments of this application, through the setting of the inner and outer connecting holes 501 and the inner wall connecting holes 502, can achieve water level balance among the three areas outside the cofferdam 1, between the inner and outer walls of the cofferdam 1, and within the cofferdam 1. This ensures that the buoyancy of the cofferdam 1 in the strong tidal water area is not affected by the tide level, thereby guaranteeing the vertical attitude of the cofferdam 1.

[0042] During the process of lowering the cofferdam 1 to its self-floating state, the internal and external connecting holes 501 on the inner wall of the cofferdam 1, the internal and external connecting holes 501 on the outer wall of the cofferdam 1, and the internal wall connecting hole 502 on the inner wall of the cofferdam 1 are opened to keep the water level inside and outside the cofferdam 1 consistent, reduce the buoyancy of the cofferdam 1, and prevent changes in the water level inside the cofferdam 1 from affecting the construction.

[0043] Meanwhile, when the measured tide level is higher than the preset tide level, the cofferdam 1 is lowered to a self-floating state through the hoisting system 3. This means that the water area where the cofferdam 1 is located is at high tide. At high tide, the water level is high and the buoyancy of the cofferdam 1 is large. Therefore, lowering the cofferdam 1 to a self-floating state at high tide can reduce the instability of the cofferdam 1 caused by changes in buoyancy during the sinking process.

[0044] In this embodiment of the application, step S3, which involves lowering the cofferdam to a self-floating state using a hoisting system, specifically includes the following steps: Step S31: Install the hanging system 3 at the top of the steel casing 4 located inside the cofferdam 1 and at the lowering point of the cofferdam 1.

[0045] Specifically, the suspension system 3 includes: a suspension beam 301, which is fixed to the top of the steel casing 4 adjacent to the cofferdam 1; and a lower anchor beam 303, which is connected to the suspension beam 301 by a sling 302 and is fixed to the cofferdam 1.

[0046] Step S32: Lift the cofferdam 1 to the detachment cofferdam 1 assembly platform via the hoisting system 3, and dismantle the cofferdam 1 assembly platform.

[0047] Specifically, the hoisting system 3 is activated to slowly lift the cofferdam 1, detaching it from the cofferdam 1 assembly platform. After the cofferdam 1 is detached from the assembly platform, preparatory work for dismantling the assembly platform is carried out, including clearing debris from the platform and removing temporary supports.

[0048] Step S33: Adjust the cofferdam 1 to a vertical position using the guide structure 6.

[0049] Specifically, the guide structure 6 includes: a base, which is fixedly connected to the inner wall of the cofferdam 1; a telescopic drive component, which is telescopically connected to the side of the base away from the cofferdam 1; and a guide component, one end of which abuts against the steel casing 4, and the other end of which is fixedly connected to the telescopic drive component. Through the arrangement of the guide structure 6, the cofferdam 1 can be effectively guided to maintain a stable vertical posture during the sinking process. If the cofferdam 1 tilts, the telescopic drive component can extend and retract, causing the guide component to push the cofferdam 1 and correct its posture.

[0050] Step S34: Lower the cofferdam 1 to its self-floating state using the hoisting system 3.

[0051] During the process of lowering cofferdam 1 to its self-floating state, the tension of the suspension system 3 is adjusted to ensure the smooth sinking of cofferdam 1. This embodiment utilizes the suspension system 3, which not only achieves the goal of sinking cofferdam 1 while it is being scoured, but also effectively prevents further sinking after cofferdam 1 has reached its final position, thus improving the safety factor of cofferdam 1. Throughout the entire cycle from the initial self-floating of cofferdam 1, through scour sinking, to its final stable positioning, the suspension system 3 remains in a stable loaded state. The continuous load support of the suspension system 3 not only provides control force for cofferdam 1 during the sinking process, but also constitutes a reliable rigid constraint after cofferdam 1 is in place, effectively offsetting settlement that may be caused by environmental loads such as water flow and sediment, thereby enhancing the stability of the project.

[0052] Step S4: Inject water between the inner and outer walls. When the monitored tide level is lower than the preset tide level, use the scouring force generated by the reciprocating flow velocity in a large water area and lower the cofferdam 1 to the preset position through the hanging system 3.

[0053] Specifically, by injecting water between the inner and outer walls of the cofferdam 1, the weight of the cofferdam 1 is increased, thereby reducing its buoyancy and making it easier to sink.

[0054] In this embodiment, the tide level of the water area where the cofferdam 1 is located is measured. When the tide level measured again is lower than the preset tide level, the cofferdam 1 is lowered to the preset position by the hoisting system 3. When the tide level measured again is lower than the preset tide level, it means that the water area where the cofferdam 1 is located is in the slack tide period. By choosing the slack tide period, the cofferdam 1 can quickly set up, thereby reducing the use of sludge suction equipment, simplifying the construction process, and improving construction efficiency.

[0055] Meanwhile, in this embodiment, by assembling the bottom compartment at the bottom of the cofferdam and utilizing the scouring force generated under conditions of high reciprocating flow velocity in a large water area, the cofferdam is lowered to a preset position through a hoisting system. This effectively utilizes the tidal surge effect to improve the water flow field at the bottom of the cofferdam, resulting in more uniform scouring of the bottom cover layer of the cofferdam. This facilitates the lowering of the cofferdam into place. Furthermore, by continuously hoisting the cofferdam to the vicinity of the top of the scouring seabed through the hoisting system, the cofferdam can be continuously lowered to the design position while being scoured, and the cofferdam can be prevented from sinking further.

[0056] Figure 3 This is a side view of the cofferdam after it has been lowered, as provided in an embodiment of this application.

[0057] Step S5: Perform bottom sealing construction at the bottom of cofferdam 1. After the bottom sealing concrete reaches the preset strength, close the inner and outer connecting holes 501, open the inner wall connecting holes 502, pump out the water in cofferdam 1, and pour the foundation.

[0058] During the bottom sealing construction of cofferdam 1, it is necessary to suction and level the mud inside cofferdam 1 and clean the outer perimeter of the steel casing 4 within the sealing area. Further, underwater leak sealing is performed between the bottom compartment 2 and the foundation. Finally, underwater sealing concrete is poured in sections.

[0059] In this embodiment, closing the inner and outer connecting holes 501, opening the inner wall connecting hole 502, pumping out the water in the cofferdam 1 and the water between the inner and outer walls, and then pouring the foundation, specifically includes: Step S51: Close the inner and outer connecting holes 501, open the inner wall connecting hole 502, and pump out the water inside the cofferdam 1 as well as the water between the inner and outer walls.

[0060] Specifically, the inner and outer connecting holes 501 are closed to ensure that water cannot enter the cofferdam 1 through these holes, and the inner wall connecting holes 502 are opened to ensure that the water in the cofferdam 1 can be discharged smoothly, while facilitating subsequent pumping operations.

[0061] Step S52: Unload the suspension system 3, cut off the steel casing 4, and remove the guide structure 6.

[0062] During the foundation pouring stage, the hanging system 3 and guide structure 6 are no longer needed. Removing the hanging system 3 and guide structure 6 can reduce their interference with construction and provide more operating space for subsequent construction, ensuring the smooth progress of construction.

[0063] Step S53: Cast the foundation, which includes a first-layer foundation and a second-layer foundation. Cast the first-layer foundation and the second-layer foundation in sequence.

[0064] In one specific embodiment, the first layer of foundation concrete has a height of 3.5m and a concrete volume of approximately 6895m³, and the second layer of foundation concrete has a height of 3.5m and a concrete volume of approximately 6895m³.

[0065] In this embodiment of the application, before the bottom sealing construction of the cofferdam 1 is carried out, the following steps are also included: In step S501, the suspension system 3 is controlled to be in a tensioned state.

[0066] After the cofferdam 1 settles at low tide, the hoisting system 3 is unloaded and tightened to ensure that the cofferdam 1 remains stable during the sinking process and to reduce the swaying of the cofferdam 1 caused by changes in tide level and water flow impact.

[0067] In step S502, water continues to be injected between the inner and outer walls until the distance between the water surface between the inner and outer walls and the top of the cofferdam 1 reaches a preset distance.

[0068] In one specific embodiment, the preset distance is 5.69m, and the water head difference between the inside and outside of the wall should not exceed 8.5m during the water injection process.

[0069] In step S503, the elevation change of cofferdam 1 is recorded. When the elevation change of cofferdam 1 does not exceed the preset change rate, the bottom sealing construction is carried out.

[0070] In this embodiment of the application, the elevation change of the cofferdam 1 at high tide and low tide is continuously observed to ensure the stability of the cofferdam 1. When the elevation change of the cofferdam 1 does not exceed the preset change rate, it means that the elevation change of the cofferdam 1 tends to be stable, and then the bottom sealing construction can be prepared.

[0071] Before sealing the bottom, the scouring depth of the cover layer needs to be measured again. If the scouring depth exceeds 10m, ton bags need to be placed outside and below the first cutting edge of the cofferdam for protection to ensure that the thickness and quality of the sealing concrete meet the requirements in subsequent construction.

[0072] After the foundation construction is completed, the construction of the tower base and the first section of the lower tower column can proceed. Specifically, diagonal bracing is added, and the internal support structure that conflicts with the main tower is removed, while retaining the two internal supports in the middle and upper layers of the middle section; the steel reinforcement of the tower base and the first section of the lower tower column is tied, and the stiffening frame of the first section of the lower tower column is installed; the concrete of the tower base and the first section of the lower tower column is poured; following the above steps, the construction of the main tower segment continues.

[0073] Secondly, embodiments of this application provide a cofferdam lowering construction device. Figure 5 This is a schematic diagram of the hanging system 3 and guide structure 6 provided in the embodiments of this application. See also Figure 5 The cofferdam 1 includes an inner wall and an outer wall. The cofferdam 1 contains multiple steel casings 4, including: a hoisting system 3 for controlling the lowering of the cofferdam 1, one end of the hoisting system 3 is fixed to the top of the steel casing 4, and the other end of the hoisting system 3 is fixed to the cofferdam 1; and multiple guide structures 6 for fixing to the inner wall of the cofferdam 1, one end of any guide structure 6 is fixedly connected to the inner wall, and the other end of any guide structure 6 abuts against the steel casing 4.

[0074] In this embodiment, the suspension system 3 includes: a suspension beam 301, which is fixed to the top of the steel casing 4 adjacent to the cofferdam 1; and a lower anchor beam 303, which is connected to the suspension beam 301 by a sling 302 and is fixed to the cofferdam 1.

[0075] In this embodiment, the guide structure 6 includes: a base, which is fixedly connected to the inner wall of the cofferdam 1; a telescopic drive member, which is telescopically connected to the side of the base away from the cofferdam 1; and a guide member, one end of which abuts against the steel casing 4, and the other end of which is fixedly connected to the telescopic drive member.

[0076] In this embodiment, the guide component is a guide wheel.

[0077] Specifically, the guide component is set as a guide wheel. The guide wheel uses rolling contact instead of sliding contact, which significantly reduces the friction between the guide wheel and the steel casing 4, making the cofferdam 1 sink more smoothly and reducing the resistance and wear caused by friction.

[0078] For technical features not disclosed in the embodiments of this application, please refer to the embodiments of the above-mentioned cofferdam lowering and pier cap casting construction methods, which will not be repeated here.

[0079] 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.

[0080] 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.

[0081] 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 method for cofferdam lowering and foundation casting, used to achieve cofferdam lowering and foundation casting in water conditions with large semi-diurnal tidal range and high reciprocating flow velocity, characterized in that, include: Monitor the real-time tide level of the waters where the cofferdam is located; When the monitored tide level is lower than the preset tide level, a cofferdam assembly platform is installed, the cofferdam is assembled on the cofferdam assembly platform, and the bottom compartment is assembled at the bottom of the cofferdam. Open the inner and outer connecting holes set on the inner wall of the cofferdam, the inner and outer connecting holes on the outer wall of the cofferdam, and the inner wall connecting hole on the inner wall of the cofferdam. When the monitored tide level is higher than the preset tide level, the cofferdam is lowered to the self-floating state through the hoisting system. Water is injected between the inner and outer walls. When the monitored tide level is lower than the preset tide level, the cofferdam is lowered to the preset position by utilizing the scouring force generated under the conditions of a large water body with reciprocating flow velocity and through the hanging system. The bottom sealing construction is carried out at the bottom of the cofferdam. After the bottom sealing concrete reaches the preset strength, the inner and outer connecting holes are closed, the inner wall connecting holes are opened, the water in the cofferdam is pumped out, and the foundation is poured.

2. The method for lowering a cofferdam and pouring a foundation according to claim 1, characterized in that, When the monitored tide level is lower than the preset tide level, a cofferdam assembly platform is installed, the cofferdam is assembled on the cofferdam assembly platform, and the bottom compartment is assembled at the bottom of the cofferdam, including: The steel casing located inside the cofferdam and at the lowering point of the cofferdam is raised to a first preset height, and the steel casing located inside the cofferdam but not at the lowering point of the cofferdam is raised to a second preset height. A connecting system is installed between multiple steel casings located inside the cofferdam. When the monitored tide level is lower than the preset tide level, a cofferdam assembly platform is welded to the outer wall of the steel casing located inside the cofferdam and at the lowering point of the cofferdam. The cofferdam is assembled sequentially on the cofferdam assembly platform, and the bottom compartment is assembled at the bottom of the cofferdam. A cutting edge is provided at the bottom edge of the cofferdam. Multiple guide structures are installed on the inner wall of the cofferdam, wherein one end of each guide structure is fixedly connected to the inner wall, and the other end of each guide structure abuts against the steel casing. Pour concrete for the bottom compartment and the cutting edge.

3. The method for lowering a cofferdam and pouring a foundation according to claim 2, characterized in that, After pouring the bottom compartment concrete and the cutting edge concrete, the following steps are also included: Monitor the seabed scour depth in the waters where the cofferdam is located, and when the monitored seabed scour depth is greater than the preset depth, dump ton bags around the cutting edge.

4. The method for lowering a cofferdam and pouring a foundation according to claim 2, characterized in that, The process of lowering the cofferdam to a self-floating state via a hoisting system specifically includes: Install a hanging system at the top of the steel casing located inside the cofferdam and at the lowering point of the cofferdam; The cofferdam is lifted to a position detached from the cofferdam assembly platform using the hoisting system, and the cofferdam assembly platform is then dismantled. The cofferdam was adjusted to a vertical position using a guide structure. The cofferdam is lowered to a self-floating state using the hoisting system.

5. The method for lowering a cofferdam and pouring a foundation according to claim 2, characterized in that, The steps of closing the inner and outer connecting holes, opening the inner wall connecting hole, pumping out the water in the cofferdam and the water between the inner and outer walls, and pouring the foundation include: Close the inner and outer connecting holes, open the inner wall connecting holes, and pump out the water inside the cofferdam as well as the water between the inner and outer walls. Unload the suspension system, cut off the steel casing, and dismantle the guide structure; The foundation is cast, wherein the foundation includes a first foundation and a second foundation, and the first foundation and the second foundation are cast sequentially.

6. The method for lowering a cofferdam and pouring a foundation according to claim 1, characterized in that, Before the sealing construction at the bottom of the cofferdam, the following is also included: Control the suspension system to a taut state; Continue injecting water between the inner wall and the outer wall until the distance between the water surface between the inner wall and the outer wall and the top of the cofferdam reaches a preset distance; Record the elevation changes of the cofferdam. When the elevation changes of the cofferdam do not exceed the preset rate of change, carry out the bottom sealing construction.

7. A cofferdam lowering construction device, the cofferdam comprising an inner wall and an outer wall, and multiple steel casings inside the cofferdam, characterized in that, include: A hoisting system for controlling the lowering of the cofferdam, one end of which is fixed to the top of the steel casing, and the other end of which is fixed to the cofferdam; Multiple guide structures are used to fix the cofferdam to the inner wall, one end of each guide structure is fixedly connected to the inner wall, and the other end of each guide structure abuts against the steel casing.

8. A cofferdam lowering construction device according to claim 7, characterized in that, The suspension system includes: A suspension beam, which is fixed to the top of a steel casing adjacent to the cofferdam; The lower anchor beam is connected to the suspension beam by a sling and is fixed to the cofferdam.

9. A cofferdam lowering construction device according to claim 7, characterized in that, The guiding structure includes: The base is fixedly connected to the inner wall of the cofferdam; A telescopic drive component, wherein the telescopic drive component is telescopically connected to the side of the base away from the cofferdam; The guide member has one end abutting against the steel casing, and the other end of the guide member is fixedly connected to the telescopic drive member.

10. A cofferdam lowering construction device according to claim 9, characterized in that, The guide component is a guide wheel.

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