Cofferdam construction method applied to waterside area and steel pipe pile cofferdam device

Abstract

The invention relates to a cofferdam construction method applied to a waterside area and a steel pipe pile cofferdam device. Steel pipe pile units are driven in a preset construction area in an inserted mode till all the steel pipe pile units surround to form a fabricated cofferdam; and cement mixing pile groups are constructed on the inner side and the outer side of the steel pipe pile unit to form a first protection structure and a second protection structure correspondingly. Cement mixing pile groups are constructed on the inner side and the outer side of each steel pipe pile unit, so that the steel pipe pile units can be enclosed, soil bodies on the inner side and the outer side of the fabricated cofferdam can be reinforced, and the inserting depth of the steel pipe pile units and the design elevation of a foundation pit can be reduced. The soil body in the fabricated cofferdam is excavated to the designed elevation of a layer of concrete ring beam, and the layer of concrete ring beam is poured; and the execution is repeated until pouring of all concrete ring beams is completed. No inner support of the fabricated cofferdam is achieved through the concrete ring beam, conversion of construction procedures is reduced, convenience of excavation operation is improved, the operability of concrete ring beam construction is high, and the construction efficiency is effectively improved.

Description

Technical Field

[0001] The present application relates to the technical field of cofferdams, and in particular to a cofferdam construction method and a steel pipe pile cofferdam device used in waterside areas. Background Art

[0002] With the rapid development of the transportation industry, bridge construction has become a key project to connect natural obstacles such as rivers and lakes. In the process of bridge construction, in order to cross special terrains such as rivers and lakes, it is often necessary to build bridge piers and foundations in areas with complex geological conditions such as river beaches and river banks. These areas are often rich in groundwater, with thick silt layers and high water content, and large thixotropic flow, which brings challenges to bridge foundation construction.

[0003] In the construction of cofferdams, in order to ensure the stability of the construction environment, the cofferdams need to be driven to a greater depth. This usually requires the use of extra-long steel pipe piles or steel sheet piles. However, these extra-long piles are difficult to process, and due to their length limitations, they cannot be directly transported to the construction site by road. Therefore, it is usually necessary to transport the piles to the site in sections, and then lengthen them by welding before driving them in. This construction method not only has a large workload and increases construction costs, but also due to the limitations of on-site supporting facilities, the welding quality is difficult to be effectively guaranteed. In addition, in the construction process of forming a deeper foundation pit, the bearing capacity of steel pipe piles or steel sheet piles is limited, which further affects the reliability of the construction. Therefore, the existing technology has many limitations in bridge foundation construction, and a new construction method or technology is urgently needed to solve the above problems in order to improve construction efficiency and reliability. Summary of the invention

[0004] Based on this, it is necessary to provide a cofferdam construction method and a steel pipe pile cofferdam device for use in waterfront areas, which can reduce the cofferdam insertion depth and ensure the reliability of cofferdam foundation pit construction in order to address the above problems.

[0005] A cofferdam construction method for use in a waterfront area, the cofferdam construction method comprising: Insert and drive the first section of steel pipe pile unit in the preset construction area; When the first section of the steel pipe pile unit is driven into place, the next section of the steel pipe pile unit is driven in, until all the steel pipe pile units are surrounded to form an assembled cofferdam; Constructing a cement mixing pile group inside the driven steel pipe pile unit to form a first protective structure; and constructing a cement mixing pile group outside the driven steel pipe pile unit to form a second protective structure; Excavating the soil in the assembled cofferdam to the designed elevation of a layer of concrete ring beam; Casting the layer of concrete ring beam at the designed elevation of the layer of concrete ring beam inside the assembled cofferdam; When the concrete ring beam of this layer reaches the designed strength, continue to excavate the soil in the assembled cofferdam to the designed elevation of the concrete ring beam of the next layer; Repeat the steps of pouring the concrete ring beam of this layer and continuing to excavate to the design elevation of the next layer of concrete ring beam until all concrete ring beams are poured; Continue to excavate the soil within the prefabricated cofferdam to the designed elevation of the foundation pit.

[0006] In one embodiment, the excavation of the soil in the assembled cofferdam to the design elevation of a layer of concrete ring beam further includes: At the designed elevation, drilling anchor holes from the inner side of the fabricated cofferdam in a direction away from the water area; pouring anchor slurry into the anchor hole; The step of pouring the concrete ring beam at the designed elevation of the concrete ring beam inside the assembled cofferdam comprises: The layer of concrete ring beam is cast at the designed elevation of the layer of concrete ring beam inside the assembled cofferdam so that the concrete ring beam covers the slurry in the anchor hole.

[0007] In one embodiment, before pouring anchor slurry into the anchor hole, the method further includes: installing an anchor rod in the anchor hole; The step of pouring the concrete ring beam at the designed elevation of the concrete ring beam inside the assembled cofferdam comprises: Fixing a steel cage of a concrete ring beam on the inner wall of the assembled cofferdam, and installing a ring beam template on the outer side of the steel cage so that the anchor rod passes through the steel cage; Casting the concrete ring beam in the ring beam template to form the concrete ring beam; When the concrete ring beam reaches the designed strength, the anchor rods are tensioned and sealed on the concrete ring beam.

[0008] In one embodiment, the method of drilling anchor holes from the inner side of the fabricated cofferdam in a direction away from the water at the designed elevation includes: At the design elevation of the upper layer of concrete ring beam of the prefabricated cofferdam, at least two anchor holes are drilled, each of which is spaced apart around the axis of the prefabricated cofferdam; wherein at least two anchor holes are drilled at the design elevation of the lower layer of concrete ring beam of the prefabricated cofferdam, each of which is spaced apart around the axis of the prefabricated cofferdam, and the anchor holes of the upper layer and the anchor holes of the lower layer are staggered in the axial direction of the prefabricated cofferdam.

[0009] In one embodiment, constructing a cement mixing pile group inside the driven steel pipe pile unit to form a first protective structure includes: Constructing a first cement mixing pile at a position adjacent to the inner side of the steel pipe pile unit mentioned in the previous section; When the next section of the steel pipe pile unit is inserted and driven into place, a first cement mixing pile is constructed on the inner side of the next section of the steel pipe pile unit and adjacent to the steel pipe pile unit, so that the first cement mixing pile is engaged with the adjacent first cement mixing pile until the first cement mixing piles are connected end to end to form a first protective unit of the first protective structure.

[0010] In one embodiment, the step of constructing a cement mixing pile group inside the driven steel pipe pile unit to form a first protective structure further includes: Constructing a plurality of second cement mixing piles in a second protection area inside the driven steel pipe pile unit, wherein each of the second cement mixing piles is arranged at intervals around the axis of the assembled cofferdam to form a second protection unit; A plurality of groups of interconnected third cement mixing piles are constructed in the third protection area inside the driven steel pipe pile unit, each group of the third cement mixing piles forms a third protection unit, and the third protection units are arranged at intervals around the axis of the prefabricated cofferdam; wherein the third protection area is located between the first protection unit and the second protection unit.

[0011] In one embodiment, the step of constructing a cement mixing pile group inside the driven steel pipe pile unit to form a first protective structure further includes: Drill a mixing hole to a preset depth on the inner side of the driven steel pipe pile unit. Spraying the first slurry into the stirring hole and circulate stirring so that the height of the first slurry is higher than the design elevation of the foundation pit; Spraying a second slurry into the stirring hole and circulate stirring until the cement stirring pile is formed, and the strength of the first slurry after solidification is greater than the strength of the second slurry after solidification; The above steps are executed cyclically to form the cement mixing pile group, so as to form the first protective structure.

[0012] In one embodiment, constructing a cement mixing pile group outside the driven steel pipe pile unit to form a second protective structure includes: A plurality of spaced mixing and positioning piles are constructed outside the steel pipe pile unit, and an interlocking pile is constructed between two of the mixing and positioning piles, so that each of the interlocking piles connects two adjacent mixing and positioning piles to form a protective wall, and each of the protective walls is spaced apart to form the second protective structure.

[0013] In one embodiment, the step of continuing to excavate the soil in the assembled cofferdam to the designed elevation of the foundation pit further includes: The bottom of the foundation pit is poured to form a cushion layer, and the thickness of the cushion layer is 0.2m-0.5m.

[0014] A steel pipe pile cofferdam device is constructed by the above-mentioned cofferdam construction method applied in waterside areas.

[0015] The above-mentioned cofferdam construction method and steel pipe pile cofferdam device used in waterfront areas insert the first section of the steel pipe pile unit in the preset construction area, and continue to insert the next section of the steel pipe pile unit until all the steel pipe pile units are surrounded to form an assembled cofferdam; a cement mixing pile group is constructed on the inner side of the steel pipe pile unit to form a first protective structure, and a cement mixing pile group is constructed on the outer side of the steel pipe pile unit to form a second protective structure. By constructing cement mixing pile groups on both the inner and outer sides of the steel pipe pile unit, on the one hand, the steel pipe pile unit can be enclosed and the deformation and internal force of the steel pipe pile unit can be reduced; on the other hand, the soil on both sides of the assembled cofferdam can be reinforced to improve the bearing capacity and surge resistance of the foundation, and then the insertion depth of the steel pipe pile unit can be appropriately reduced, and the design elevation of the foundation pit can also be appropriately reduced. Then, start to excavate the soil in the prefabricated cofferdam to the design elevation of a layer of concrete ring beam and cast the concrete ring beam of this layer; when the concrete ring beam of this layer reaches the design strength, continue to excavate the soil in the prefabricated cofferdam to the design elevation of the next layer of concrete ring beam and cast the concrete ring beam of this layer, repeat until all concrete ring beams are cast; continue to excavate the soil in the prefabricated cofferdam to the design elevation of the foundation pit. Since the structural strength of the prefabricated cofferdam and the stability of the foundation are guaranteed by the construction of the first and second protective structures, the construction of the concrete ring beam on the inner wall of the prefabricated cofferdam not only further improves the stability of the prefabricated cofferdam structure, but also the construction of the concrete ring beam is highly operable, effectively improving the construction efficiency, realizing the prefabricated cofferdam without internal support, without obstacles in the middle of the cofferdam, reserving sufficient construction space, reducing process conversion, and increasing the convenience of excavation operations. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application.

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0018] In addition, the drawings are not drawn to a 1:1 scale, and the relative sizes of various elements are drawn only as examples in the drawings and are not necessarily drawn according to the true scale.

[0019] Figure 1 The present invention is a flow chart of a cofferdam construction method applied in a waterfront area according to an embodiment.

[0020] Figure 2 It is a structural schematic diagram of a steel pipe pile cofferdam device in an embodiment used in a waterside area.

[0021] Figure 3 for Figure 2 A partial top view of the steel pipe pile cofferdam device shown.

[0022] Figure 4 for Figure 2 The steel pipe pile cofferdam device shown omits a partial top view of the first protective structure and the second protective structure.

[0023] Figure 5 for Figure 4 The cross-sectional view of the steel pipe pile cofferdam device along line AA is shown.

[0024] Figure 6 for Figure 4 The cross-sectional view of the steel pipe pile cofferdam device along line BB is shown.

[0025] Figure 7 for Figure 6 Enlarged view of point C in the middle.

[0026] Description of reference numerals: Steel pipe pile cofferdam device 10; assembled cofferdam 100; steel pipe pile unit 110; foundation pit 120; anchor hole 130; concrete ring beam 200; first protective structure 300; first protective unit 301; second protective unit 302; third protective unit 303; first cement mixing pile 310; second cement mixing pile 320; third cement mixing pile 330; second protective structure 400; mixing positioning pile 410; bite pile 420; protective wall 402; anchor assembly 500; anchor rod 510; anchor head 520; cushion layer 700. DETAILED DESCRIPTION

[0027] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0028] See also Figures 1 to 3 , the cofferdam construction method used in the waterside area in one embodiment of the present application is used to construct a steel pipe pile cofferdam device 10. A foundation pit is constructed in the waterside area and a cap is cast. The geological conditions in the waterside area are complex and the thickness of the silty soil layer is large. If the water level in the water area drops rapidly, the pore water pressure inside the slope of the water area cannot be dissipated in time, and the pressure difference causes seepage from the inside of the slope to the outside of the slope. If the water level in the water area rises suddenly, the water rate in the slope increases and the thixotropic flow increases. The steel pipe pile cofferdam device 10 needs to be constructed in such an area, so it is particularly important to ensure the stability of the construction environment and the reliability of the structure of the steel pipe pile cofferdam device 10 after construction.

[0029] In one embodiment, a cofferdam construction method applied in a waterfront area includes: Step S1: inserting and driving the first section of steel pipe pile unit 110 in a preset construction area; Step S2: After the first section of the steel pipe pile unit 110 is driven into place, the next section of the steel pipe pile unit 110 is driven in, until all the steel pipe pile units 110 are surrounded to form an assembled cofferdam 100 .

[0030] Since the construction is carried out in a place with soft soil, the steel pipe pile units 110 can be directly inserted into the soil. The steel pipe pile units 110 are connected end to end to form an assembled cofferdam 100, so as to facilitate the excavation of the foundation pit 120 in the assembled cofferdam 100.

[0031] Step S3: Construct a cement mixing pile group inside the driven steel pipe pile unit 110 to form a first protective structure 300. The first protective structure 300 formed by constructing a cement mixing pile group inside the steel pipe pile unit 110 can reinforce the soil inside the steel pipe pile unit 110, ensure the stability of the subsequent foundation pit 120 construction, and provide internal support for the prefabricated cofferdam 100 to ensure the reliability of the construction of the prefabricated cofferdam 100. Specifically, when a section of the steel pipe pile unit 110 is driven into place, the construction of the cement mixing pile located inside can be started. The steel pipe pile unit 110 can locate the construction position of the cement mixing pile, and at the same time improve the construction efficiency.

[0032] In this embodiment, the step S3 includes: Step S31: constructing a first cement mixing pile 310 at a position adjacent to the inner side of the steel pipe pile unit 110 that has been driven in the previous section; Step S32: After the steel pipe pile unit 110 of the next section is driven into place, a first cement mixing pile 310 is constructed on the inner side of the steel pipe pile unit 110 of the next section and adjacent to the steel pipe pile unit 110, so that the first cement mixing pile 310 is engaged with the adjacent first cement mixing pile 310, until the first cement mixing piles 310 are connected end to end to form the first protection unit 301 of the first protection structure 300.

[0033] By constructing the first cement mixing pile 310 at a position close to the steel pipe pile unit 110, the first cement mixing pile 310 can be directly supported on the steel pipe pile unit 110. At the same time, since the first cement mixing piles 310 are interlocked together to form the first protection unit 301, the first protection unit 301 is evenly and stably supported on the inner side of the assembled cofferdam 100, ensuring the uniformity of force at each position. In other embodiments, the first cement mixing piles 310 may not be interlocked or partially interlocked together.

[0034] Furthermore, the step S3 further includes: Step S33: constructing a plurality of second cement mixing piles 320 in a second protection area inside the driven steel pipe pile unit 110, wherein each of the second cement mixing piles 320 is arranged at intervals around the axis of the assembled cofferdam 100 to form a second protection unit 302; Step S34: construct a plurality of groups of interconnected third cement mixing piles 330 in the third protection area inside the driven steel pipe pile unit 110, each group of the third cement mixing piles 330 forms a third protection unit 303, and each third protection unit 303 is arranged at intervals around the axis of the prefabricated cofferdam 100; wherein the third protection area is located between the first protection unit 301 and the second protection unit 302.

[0035] The second cement mixing piles 320 can reinforce the entire area of ​​the foundation 20 construction, ensuring the reliability of the subsequent support of the foundation 20; and the uniform arrangement of the second cement mixing piles 320 can improve the uniformity of the support. The first protection unit 301 and the second protection unit 302 are connected by the third protection unit 303 formed by the third cement mixing piles 330, and the third protection units 303 are arranged at intervals, so as to avoid the construction of too many cement mixing piles while reinforcing the soil inside the assembled cofferdam 100.

[0036] During construction, after inserting a section or part of the steel pipe pile unit 110, the construction of the first cement mixing pile 310 of the first protection unit 301 and the second cement mixing pile 320 of the second protection unit 302 can be started first. After the first cement mixing pile 310 and the second cement mixing pile 320 are solidified, the construction of the third cement mixing pile 330 of the third protection unit 303 can be started, thereby improving the construction efficiency while ensuring the effect of reinforcing the soil.

[0037] Furthermore, the step S3 further includes: Step S35: drilling a stirring hole to a preset depth inside the driven steel pipe pile unit 110, injecting first mud into the stirring hole and circulating stirring to make the height of the first mud higher than the designed elevation of the foundation pit 120; Step S36: injecting a second slurry into the stirring hole and stirring the slurry in a cycle until the cement stirring pile is formed and the strength of the first slurry after solidification is greater than the strength of the second slurry after solidification; Step S37: cyclically executing the above steps to form the cement mixing pile group, so as to form the first protective structure 300 .

[0038] The cement mixing pile group forming the first protective structure 300 is located inside the assembled cofferdam 100. In the subsequent construction, the interior of the assembled cofferdam 100 needs to be excavated to form a foundation pit 120, so as to facilitate the pouring of the cap 20. Then, the part of the cement mixing pile forming the first protective structure 300 located on the foundation pit 120 is formed by the second mud, and the strength of the second mud after solidification is less than the first mud, so it is easy to be removed in the subsequent construction, which reduces the difficulty of excavation and ensures the construction efficiency.

[0039] Step S4: constructing a cement mixing pile group outside the driven steel pipe pile unit 110 to form a second protective structure 400. By forming the second protective structure 400 outside the steel pipe pile unit 110, it can cooperate with the first protective structure 300 to reinforce the inside and outside of the steel pipe pile unit 110 at the same time, further improving the reliability of the steel pipe pile unit 110 and the formed assembled cofferdam 100.

[0040] Specifically, the step S4 includes: A plurality of interval stirring and positioning piles 410 are constructed outside the steel pipe pile unit 110, and an interlocking pile 420 is constructed between two of the stirring and positioning piles 410, so that each of the interlocking piles 420 connects two adjacent stirring and positioning piles 410 to form a protective wall 402, and each of the protective walls 402 is arranged at intervals to form the second protective structure 400. The second protective structure 400 can improve the foundation strength outside the assembled cofferdam 100 and reduce the lateral pressure of the soil on the assembled cofferdam 100. And because the formed protective walls 402 are arranged at intervals and staggered, a detour channel can be formed, which can reduce the influence of external soil creep or deformation on the assembled cofferdam 100 while strengthening, and avoid the protective wall 402 being completely enclosed outside the assembled cofferdam 100, and avoid the pressure of soil creep or deformation being all applied to the second protective structure 400, which affects the reliability of the second protective structure 400.

[0041] See also Figure 1 , Figures 4 to 7 In one embodiment, the cofferdam construction method used in a waterfront area further includes: Step S5: excavating the soil in the assembled cofferdam 100 to the designed elevation of a layer of concrete ring beam 200; Step S51: At the designed elevation, an anchor hole 130 is drilled from the inner side of the fabricated cofferdam 100 in a direction away from the water area.

[0042] Step S52: pouring anchoring slurry into the anchoring hole 130; Step S6: pouring the layer of concrete ring beam 200 at the designed elevation of the layer of concrete ring beam 200 inside the assembled cofferdam 100; Step S61: pouring the layer of concrete ring beam 200 at the designed elevation of the layer of concrete ring beam 200 inside the assembled cofferdam 100 so that the concrete ring beam 200 covers the slurry in the anchor hole 130 .

[0043] like Figure 2As shown, when the water level in the water area rises or falls, the infiltration line in the slope will also rise or fall accordingly. The prefabricated cofferdam 100 is built on silt soil. The subsequent construction base will exert gravity on the silt soil. The silt at the base of the cofferdam is prone to slip under the gravity of the structure, which may cause the prefabricated cofferdam 100 to become unstable. Therefore, by drilling the anchor hole 130 directly on the inner side of the prefabricated cofferdam 100 in the direction away from the water area, and grouting the anchor assembly 500 in the anchor hole 130, it is possible to resist the horizontal deformation of the silt soil caused by the change of water level. At the same time, the anchor assembly 500 is fixed by the concrete ring beam 200 on the inner side of the prefabricated cofferdam 100. The concrete ring beam 200 fixes the anchor assembly 500 while supporting the structural stability of the prefabricated cofferdam 100. The setting of the concrete ring beam 200 eliminates the need for an internal support structure in the assembled cofferdam 100. On the one hand, it can reduce the impact of cross-construction, increase the convenience of excavation operations, effectively reduce the excavation period of the foundation pit 120, seal the bottom as soon as possible, and improve the construction safety of the foundation pit 120; on the other hand, it can optimize the layered construction process of the cap 20 and reduce the process conversion time; there are no obstacles in the cofferdam, which has little impact on the construction of the cap 20, effectively improving the construction efficiency of the cap 20. In addition, the concrete ring beam 200 has high construction redundancy and easy control of precision. Compared with the steel purlin, it fully utilizes the structural force characteristics of the circular concrete ring beam 200; the concrete ring beam 200 only uses concrete materials, which greatly saves the amount of circulating materials such as steel.

[0044] In this embodiment, the step S51 then includes: Installing an anchor rod 510 in the anchor hole 130; A steel cage of a concrete ring beam 200 is fixed on the inner wall of the assembled cofferdam 100, and a ring beam template is installed on the outer side of the steel cage so that the anchor rod 510 passes through the steel cage; Casting the concrete ring beam 200 in the ring beam template; When the concrete ring beam 200 reaches the designed strength, the anchor rod 510 is tensioned and the anchor rod 510 is sealed on the concrete ring beam 200; Step S7: When the concrete ring beam 200 of this layer reaches the designed strength, continue to excavate the soil in the assembled cofferdam 100 to the designed elevation of the concrete ring beam 200 of the next layer; Step S8: Repeat the steps of pouring the current layer of concrete ring beams 200 and continuing to excavate to the design elevation of the next layer of concrete ring beams 200 until the pouring of all concrete ring beams 200 is completed.

[0045] Since the stratum at the construction location is weak, the anchor rod 510 is inserted into the anchor hole 130 to improve the anchoring effect on the assembled cofferdam 100 and improve the ability to resist soil deformation and displacement in the horizontal direction. At the same time, since one end of the anchor rod 510 is anchored in the soil and the other end is fixed on the concrete ring beam 200, the concrete ring beam 200 can be firmly pressed against the inner wall of the assembled cofferdam 100 by the tension of the anchor rod 510. In other embodiments, the anchor rod 510 can also be omitted, and the anchor assembly 500 is directly formed by grouting in the anchor hole 130. In this embodiment, grouting can be performed by high-pressure splitting grouting to further improve the anchoring effect of the anchor assembly 500. For example, grouting can be performed by secondary grouting.

[0046] like Figure 4 and Figure 6 As shown, in this embodiment, the cofferdam construction method includes: At the design elevation of the upper layer of concrete ring beam 200 of the prefabricated cofferdam 100, at least two of the anchor holes 130 are drilled, and each of the anchor holes 130 is spaced apart around the axis of the prefabricated cofferdam 100; wherein at least two of the anchor holes 130 are drilled at the design elevation of the lower layer of concrete ring beam 200 of the prefabricated cofferdam 100, and each of the anchor holes 130 is spaced apart around the axis of the prefabricated cofferdam 100, and the anchor holes 130 of the upper layer and the anchor holes 130 of the lower layer are staggered in the axial direction of the prefabricated cofferdam 100.

[0047] By providing at least two layers of concrete ring beams 200, the reliability of fixing the prefabricated cofferdam 100 can be improved, and anchoring assemblies 500 are provided at the position of each layer of concrete ring beams 200, so that the prefabricated cofferdam 100 can be anchored at different positions at different depths, thereby improving the reliability of anchoring, and the anchoring assemblies 500 on different layers are staggered, so that anchoring can be achieved at different circumferential positions of the prefabricated cofferdam 100.

[0048] In one embodiment, the cofferdam construction method further includes: When the upper layer of concrete ring beam 200 is poured, when excavation is carried out to the designed elevation of the next layer of concrete ring beam 200, the first supporting column can be poured synchronously when pouring the next layer of concrete ring beam 200, so that the opposite ends of the first supporting column abut against two adjacent concrete ring beams 200.

[0049] In one embodiment, the cofferdam construction method further includes: Step S9: Continue to excavate the soil in the assembled cofferdam 100 to the designed elevation of the foundation pit 120 .

[0050] Specifically, the cofferdam construction method further includes: pouring the bottom of the foundation pit 120 to form a cushion layer 700, and the thickness of the cushion layer 700 is 0.2m-0.5m.

[0051] The present application forms a first protective structure 300 and a second protective structure 400 by constructing cement mixing pile groups on both the inner and outer sides of the prefabricated cofferdam 100. The anchor assembly 500 is provided to improve the stability of the prefabricated cofferdam 100 in the soil, and to increase the ability of the prefabricated cofferdam 100 to resist horizontal surge and deformation. The concrete ring beam 200 is provided on the inner side of the prefabricated cofferdam 100 to achieve the prefabricated cofferdam 100 without internal support, so that the thickness of the cushion layer 700 cast on the bottom wall of the foundation pit 120 can be reduced to 0.2m-0.5m. The thickness of the traditional cushion layer 700 generally needs to be more than 3m. Compared with the traditional solution, the excavation depth of the foundation pit 120 can be reduced by about 3m, and the insertion depth of the steel pipe pile unit 110 can be reduced by at least 3m, which can reduce the use of at least 3m of the steel pipe pile unit 110, improve the construction efficiency, and save the use of steel.

[0052] In one embodiment, the cofferdam construction method further includes: When excavation reaches the designed elevation of the foundation pit 120, a second supporting column can be cast between the bottom wall of the foundation pit 120 and the concrete ring beam 200 at the lowest layer, so that the opposite ends of the second supporting column are respectively abutted against the bottom wall of the foundation pit 120 and the concrete ring beam 200 at the lowest layer.

[0053] It can be seen from the above records that the present application forms a first protective structure 300 and a second protective structure 400 by constructing cement mixing pile groups on both the inner and outer sides of the steel pipe pile unit 110. On the one hand, it can enhance the protection of the steel pipe pile unit 110 and reduce the deformation and internal force of the steel pipe pile unit 110; on the other hand, it can reinforce the soil on both sides of the prefabricated cofferdam 100, improve the bearing capacity and surge resistance of the foundation, and then the driving depth of the steel pipe pile unit 110 can be appropriately reduced, and the design elevation of the foundation pit 120 can also be appropriately reduced.

[0054] Then, by setting a concrete ring beam 200 on the inner side of the assembled cofferdam 100 and opening an anchor hole 130 at the position of the concrete ring beam 200 for anchoring, not only the stability of the assembled cofferdam 100 structure is further improved, but also the construction operability of the concrete ring beam 200 is high, the construction efficiency is effectively improved, and the assembled cofferdam 100 is realized without internal support, there are no obstacles in the middle of the cofferdam, sufficient construction space is reserved, the cross-influence is reduced, the convenience of excavation operations is increased, and the process conversion is less. And by forming an anchor assembly 500 in the anchor hole 130, the ability of the assembled cofferdam 100 to resist horizontal surge and deformation can be increased. In the present application, the assembled cofferdam 100 can be a permanent cofferdam, and the assembled cofferdam 100 can be used to protect the internal cap 20 structure, and improve the service life of the cap 20 and the reliability during use.

[0055] It should be understood that although Figure 1 The steps in the flowchart are shown in sequence as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders. Moreover, Figure 1 At least part of the steps may include multiple steps or multiple stages. These steps or stages are not necessarily performed at the same time, but can be performed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed in turn or alternately with other steps or at least part of the steps or stages in other steps.

[0056] like Figures 2 to 4 As shown, in one embodiment, the present application further discloses a steel pipe pile cofferdam device 10, which is constructed by the cofferdam construction method applied in a waterfront area in any of the above embodiments.

[0057] Specifically, the steel pipe pile cofferdam device 10 includes a plurality of steel pipe pile units 110, a concrete ring beam 200, a first protective structure 300 and a second protective structure 400. The plurality of steel pipe pile units 110 are plugged in sequence, and the plurality of steel pipe pile units 110 are gathered together to form an assembled cofferdam 100. There are at least two concrete ring beams 200, and each concrete ring beam 200 is arranged on the inner wall of the assembled cofferdam 100 at intervals along the depth direction of the assembled cofferdam 100. The first protective structure 300 and the second protective structure 400 are both composed of a cement mixing pile group. The first protective structure 300 is arranged on the inner side of the assembled cofferdam 100, and the second protective structure 400 is arranged on the outer side of the assembled cofferdam 100.

[0058] In one embodiment, the first protective structure 300 includes a first protective unit 301, and the first protective unit 301 includes a plurality of first cement mixing piles 310, each of which is arranged around the axis of the prefabricated cofferdam 100 and is adjacent to the inner wall of the prefabricated cofferdam 100, and a single first cement mixing pile 310 is engaged with an adjacent first cement mixing pile 310, and each first cement mixing pile 310 is connected end to end.

[0059] In one embodiment, the first protection structure 300 further includes a second protection unit 302 and a third protection unit 303, the second protection unit 302 includes a plurality of second cement mixing piles 320, the third protection unit 303 includes a plurality of third cement mixing piles 330, the second protection unit 302 is arranged in the first protection unit 301 and is spaced apart from the first protection unit 301, and each second cement mixing pile 320 is spaced apart, and the third protection unit 303 is arranged between the first protection unit 301 and the second protection unit 302. There are a plurality of third protection units 303, and each third protection unit 303 is spaced apart around the axis of the assembled cofferdam 100. In this embodiment, each third protection unit 303 is formed by the engagement of a plurality of third cement mixing piles 330.

[0060] In one embodiment, the second protective structure 400 includes a plurality of spaced mixing and positioning piles 410 and a plurality of interlocking piles 420. The interlocking piles 420 are constructed between two mixing and positioning piles 410, so that each interlocking pile 420 connects two adjacent mixing and positioning piles 410 to form a protective wall 402. The protective walls 402 are spaced to form the second protective structure 400. Each protective wall 402 forms a circuitous passage outside the assembled cofferdam 100.

[0061] See also Figures 4 to 7 In one embodiment, the steel pipe pile cofferdam device 10 further includes an anchor assembly 500, and an anchor hole 130 is drilled from the inner side of the assembled cofferdam 100 toward a direction away from the water area. One end of the anchor assembly 500 is fixed to the concrete ring beam 200 of the assembled cofferdam 100, and the other end is penetrated into the anchor hole 130 and anchored. Specifically, the anchor assembly 500 includes an anchor rod 510 and an anchor head 520, one end of the anchor rod 510 is penetrated into the anchor hole 130, and the other end is penetrated into the concrete ring beam 200, and is fixed to the concrete ring beam 200 through the anchor head 520.

[0062] In this embodiment, there are at least two concrete ring beams 200, and each of the concrete ring beams 200 is provided with an anchor assembly 500. Specifically, the anchor assemblies 500 on each concrete ring beam 200 are arranged at intervals, and the anchor assemblies 500 of the upper layer of concrete ring beams 200 and the anchor assemblies 500 of the lower layer of concrete ring beams 200 are staggered in the axial direction of the assembled cofferdam 100.

[0063] The steel pipe pile cofferdam device 10 of the present application can reinforce the soil on both sides of the prefabricated cofferdam 100 by constructing cement mixing pile groups on both sides of the steel pipe pile unit 110 to form a first protective structure 300 and a second protective structure 400, thereby enhancing the protection of the steel pipe pile unit 110 and reducing the deformation and internal force of the steel pipe pile unit 110. Then, by setting a concrete ring beam 200 on the inner side of the prefabricated cofferdam 100, the stability of the structure of the prefabricated cofferdam 100 can be further improved, and by setting an anchor assembly 500 at the position of the concrete ring beam 200, the ability of the prefabricated cofferdam 100 to resist horizontal surge and deformation can be increased.

[0064] In the description of the present application, it should be understood that if the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "axial", "radial", "circumferential", etc. appear, the orientation or position relationship indicated by these terms is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0065] In addition, if the terms "first" or "second" appear, these terms are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, if the term "plurality" appears, "plurality" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0066] In this application, unless otherwise clearly specified and limited, if the terms "installed", "connected", "connected", "fixed" and the like appear, these terms should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0067] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described 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.

[0068] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.

Claims

1. A cofferdam construction method used in a waterfront area, characterized in that: The cofferdam construction method comprises: Insert and drive the first section of steel pipe pile unit in the preset construction area; When the first section of the steel pipe pile unit is driven into place, the next section of the steel pipe pile unit is driven in, until all the steel pipe pile units are surrounded to form an assembled cofferdam; Constructing a cement mixing pile group inside the driven steel pipe pile unit to form a first protective structure; and constructing a cement mixing pile group outside the driven steel pipe pile unit to form a second protective structure; Excavating the soil in the assembled cofferdam to the designed elevation of a layer of concrete ring beam; Casting the layer of concrete ring beam at the designed elevation of the layer of concrete ring beam inside the assembled cofferdam; When the concrete ring beam of this layer reaches the designed strength, continue to excavate the soil in the assembled cofferdam to the designed elevation of the concrete ring beam of the next layer; Repeat the steps of pouring the concrete ring beam of this layer and continuing to excavate to the design elevation of the next layer of concrete ring beam until all concrete ring beams are poured; Continue to excavate the soil within the prefabricated cofferdam to the designed elevation of the foundation pit.

2. The cofferdam construction method according to claim 1, characterized in that: The method further comprises: excavating the soil in the assembled cofferdam to the design elevation of a layer of concrete ring beam, and then: At the designed elevation, drilling anchor holes from the inner side of the fabricated cofferdam in a direction away from the water area; pouring anchor slurry into the anchor hole; The step of pouring the concrete ring beam at the designed elevation of the concrete ring beam inside the assembled cofferdam comprises: The layer of concrete ring beam is cast at the designed elevation of the layer of concrete ring beam inside the assembled cofferdam so that the concrete ring beam covers the slurry in the anchor hole.

3. The cofferdam construction method according to claim 2, characterized in that: Before pouring anchor slurry into the anchor hole, the method further comprises: installing an anchor rod in the anchor hole; The step of pouring the concrete ring beam at the designed elevation of the concrete ring beam inside the assembled cofferdam comprises: Fixing a steel cage of a concrete ring beam on the inner wall of the assembled cofferdam, and installing a ring beam template on the outer side of the steel cage so that the anchor rod passes through the steel cage; Casting the concrete ring beam in the ring beam template to form the concrete ring beam; When the concrete ring beam reaches the designed strength, the anchor rods are tensioned and sealed on the concrete ring beam.

4. The cofferdam construction method according to claim 3, characterized in that: The method of drilling anchor holes at the designed elevation from the inner side of the assembled cofferdam in a direction away from the water area includes: At the design elevation of the upper layer of concrete ring beam of the prefabricated cofferdam, at least two anchor holes are drilled, each of which is spaced apart around the axis of the prefabricated cofferdam; wherein at least two anchor holes are drilled at the design elevation of the lower layer of concrete ring beam of the prefabricated cofferdam, each of which is spaced apart around the axis of the prefabricated cofferdam, and the anchor holes of the upper layer and the anchor holes of the lower layer are staggered in the axial direction of the prefabricated cofferdam.

5. The cofferdam construction method according to any one of claims 1 to 4, characterized in that: The step of constructing a cement mixing pile group inside the driven steel pipe pile unit to form a first protective structure includes: Constructing a first cement mixing pile at a position adjacent to the inner side of the steel pipe pile unit mentioned in the previous section; When the next section of the steel pipe pile unit is inserted and driven into place, a first cement mixing pile is constructed on the inner side of the next section of the steel pipe pile unit and adjacent to the steel pipe pile unit, so that the first cement mixing pile is engaged with the adjacent first cement mixing pile until the first cement mixing piles are connected end to end to form a first protective unit of the first protective structure.

6. The cofferdam construction method according to claim 5, characterized in that: The step of constructing a cement mixing pile group inside the driven steel pipe pile unit to form a first protective structure also includes: Constructing a plurality of second cement mixing piles in a second protection area inside the driven steel pipe pile unit, wherein each of the second cement mixing piles is arranged at intervals around the axis of the assembled cofferdam to form a second protection unit; A plurality of groups of interconnected third cement mixing piles are constructed in the third protection area inside the driven steel pipe pile unit, each group of the third cement mixing piles forms a third protection unit, and the third protection units are arranged at intervals around the axis of the prefabricated cofferdam; wherein the third protection area is located between the first protection unit and the second protection unit.

7. The cofferdam construction method according to claim 6, characterized in that: The step of constructing a cement mixing pile group inside the driven steel pipe pile unit to form a first protective structure also includes: Drill a mixing hole to a preset depth on the inner side of the driven steel pipe pile unit. Spraying the first slurry into the stirring hole and circulate stirring so that the height of the first slurry is higher than the design elevation of the foundation pit; Spraying a second slurry into the stirring hole and circulate stirring until the cement stirring pile is formed, and the strength of the first slurry after solidification is greater than the strength of the second slurry after solidification; The above steps are executed cyclically to form the cement mixing pile group, so as to form the first protective structure.

8. The cofferdam construction method according to any one of claims 1 to 4, characterized in that: The method of constructing a cement mixing pile group outside the driven steel pipe pile unit to form a second protective structure includes: A plurality of spaced mixing and positioning piles are constructed outside the steel pipe pile unit, and an interlocking pile is constructed between two of the mixing and positioning piles, so that each of the interlocking piles connects two adjacent mixing and positioning piles to form a protective wall, and each of the protective walls is spaced apart to form the second protective structure.

9. The cofferdam construction method according to any one of claims 1 to 4, characterized in that: The method further comprises: The bottom of the foundation pit is poured to form a cushion layer, and the thickness of the cushion layer is 0.2m-0.5m.

10. A steel pipe pile cofferdam device, characterized in that: The steel pipe pile cofferdam device is constructed by the cofferdam construction method for use in waterfront areas as described in any one of claims 1 to 9.

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