Combined cofferdam, calculation method and construction method

Abstract

This invention provides a combined cofferdam, a calculation method, and a construction method. The combined cofferdam comprises: two rows of pile structures, each row including: an outer pile assembly comprising a first steel waler, multiple sheet piles, and multiple first steel pipe piles, with the sheet piles and first steel pipe piles alternately connected sequentially, and the top of the sheet piles being lower than the top of the first steel pipe piles; the first steel waler being located outside the multiple first steel pipe piles; multiple sets of inner pile assemblies located inside the outer pile assembly; each set of inner pile assemblies including a second steel waler and multiple second steel pipe piles, the second steel waler being located outside the multiple second steel pipe piles, with adjacent second steel pipe piles maintaining a gap; and tie rod assemblies corresponding to the inner pile assemblies, with both ends of the tie rod assemblies penetrating through the first and second steel walers. This invention can reasonably avoid the inclined arrangement of the bridge pier piles to be constructed and enhances the stability of the cofferdam structure.

Description

Technical Field

[0001] This invention relates to the field of civil engineering technology, and in particular to a combined cofferdam, calculation method, and construction method. Background Technology

[0002] In the construction of water conservancy, bridge and port projects, cofferdams are widely used as temporary water-retaining structures in the construction of rivers, lakes and other water areas to ensure dry construction conditions.

[0003] Traditional cofferdam structures often employ continuous double-row piles, typically composed of sheet piles or steel pipe piles, offering a certain degree of water-retaining capacity and structural stability. However, in practical applications, when the riverbank is not perpendicular to the cofferdam support piles—that is, when there is an angle between the bridge deck of the main bridge to be built and the riverbank—the connection lines of multiple piers must be arranged at an angle. Traditional continuous double-row piles cannot reasonably avoid the locations of the main bridge piers, making pier construction impossible. Furthermore, in complex conditions with deep water (approximately 6-7 meters), the cross-sectional stiffness and overall strength of traditional continuous double-row piles are insufficient to meet construction safety requirements, easily leading to structural failures such as deformation and overturning. Additionally, the calculation methods for double-row piles cannot fully calculate the overall stability, overturning resistance, and stress state of the tensile reinforcement.

[0004] Therefore, it is necessary to provide a combined cofferdam, calculation method, and construction method to solve the above-mentioned problems existing in the prior art. Summary of the Invention

[0005] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a combined cofferdam, calculation method and construction method to solve the technical problem that the prior art cannot reasonably avoid the location of the main bridge piers to be built, resulting in the inability to carry out pier construction.

[0006] To achieve the above and other related objectives, a first aspect of the present invention provides a combined cofferdam, comprising:

[0007] The structure consists of two rows of piles, each row including:

[0008] The external pile assembly includes a first steel waler, multiple steel sheet piles, and multiple first steel pipe piles. The multiple steel sheet piles and the multiple first steel pipe piles are connected alternately in sequence, and the top of the steel sheet piles is lower than the top of the first steel pipe piles. The first steel waler is disposed on the outside of the multiple first steel pipe piles.

[0009] Multiple sets of inner pile components are located inside the outer pile components; each set of inner pile components includes a second steel waler and multiple second steel pipe piles, the second steel waler is disposed outside the multiple second steel pipe piles, and adjacent second steel pipe piles are spaced apart;

[0010] A tie rod assembly is provided corresponding to the inner pile assembly, with both ends of the tie rod assembly passing through the first steel waler and the second steel waler.

[0011] The combined cofferdam provided by the first aspect of the present invention has the following beneficial effects:

[0012] Multiple sheet piles and multiple first steel pipe piles are sequentially and alternately connected, with a first steel waler set on the outside of the multiple first steel pipe piles, thus forming an outer row of piles; a second steel waler is set on the outside of the multiple second steel pipe piles, thus forming an inner row of piles; and the top of the sheet piles is lower than the top of the first steel pipe piles, with adjacent second steel pipe piles maintaining a gap, so that both ends of the tie rod assembly can penetrate through the first and second steel walers; the outer row of piles and the inner row of piles are anchored to the tie rod assembly to form a force-bearing system, which satisfies the requirement of cutting off the river in deep rivers to form a stable double-row pile retaining structure; and in application scenarios where the riverbank and the cofferdam support piles are not perpendicular, the combined cofferdam of this invention can reasonably avoid the inclined pile positions of the piers to be built when constructing bridge piers in the river channel, providing a dry and convenient construction environment, effectively saving steel consumption and construction costs.

[0013] Furthermore, each set of tie rod assemblies includes multiple tie rods, each tie rod being located between adjacent second steel pipe piles; both the first steel waler and the second steel waler are provided with through holes adapted to the tie rods, and both ends of the tie rods pass through the through holes to install the tie rods onto the first steel waler and the second steel waler.

[0014] Furthermore, it also includes anchor assemblies corresponding to the tie rod assembly. Each set of anchor assemblies includes two pairs of anchors. Each pair of anchors is respectively sleeved on both ends of the tie rod and located on the outside of the first steel waler and the second steel waler.

[0015] Furthermore, it also includes a corbel support plate assembly, which includes a first corbel support plate and a second corbel support plate. The first corbel support plate is fixedly connected to the outside of the first steel pipe pile and is used to support the first steel waler; the second corbel support plate is fixedly connected to the outside of the second steel pipe pile and is used to support the second steel waler.

[0016] Furthermore, it also includes a counter-pressure plate assembly, which includes a first counter-pressure plate and a second counter-pressure plate. The first counter-pressure plate is fixedly connected to the outside of the first steel pipe pile and is located above the first steel waler; the second counter-pressure plate is fixedly connected to the outside of the second steel pipe pile and is located above the second steel waler.

[0017] Furthermore, the adjacent sheet piles are detachably connected to the first steel pipe pile via a locking mechanism.

[0018] To achieve the above and other related objectives, a second aspect of the present invention provides a combined cofferdam calculation method, comprising:

[0019] Based on the construction drawings of the combined cofferdam, the outer area of ​​the outer pile assembly is designated as the water-facing area, and the area between the outer pile assembly and the inner pile assembly is designated as the filling area.

[0020] Based on the stress conditions of the outer and inner pile components in the water-facing and filling areas, as well as the stress conditions between the outer and inner pile components, mechanical calculation models of the outer and inner pile components are constructed to determine the mechanical parameters to be calculated for the outer and inner pile components.

[0021] Based on finite element analysis software and combined with the mechanical calculation models of the outer and inner pile components, the normal stress and maximum horizontal displacement values ​​of the outer and inner pile components were calculated respectively.

[0022] Verify whether the calculated normal stress and maximum horizontal displacement values ​​of the outer and inner pile components meet the preset requirements of the outer and inner pile components. If both the outer and inner pile components meet the preset requirements, construction shall be carried out based on the construction drawings of the combined cofferdam. If either the outer or inner pile component does not meet the preset requirements, the construction drawings shall be redesigned.

[0023] The combined cofferdam calculation method provided in the second aspect of the present invention has the following beneficial effects:

[0024] The combined cofferdam calculation method provided by this invention improves the calculation theory of double-row cofferdam structures, and fully calculates the structural stability, overturning resistance, tension and other stress states of double-row cofferdam structures. This can accurately simulate subsequent actual construction, ensure the safety of actual construction, and reduce construction costs.

[0025] Furthermore, based on the established stress conditions of the outer and inner pile components in the water-facing and filling areas, as well as the stress conditions between the outer and inner pile components, a mechanical calculation model of the outer and inner pile components is constructed to determine the mechanical parameters to be calculated for the outer and inner pile components. This process includes: dividing the stress stages of the outer and inner pile components into a filling stage and an actual construction stage; based on the established stress conditions of the outer pile components in the water-facing and filling areas, as well as the anchoring forces of the inner pile components and tie rod components on the outer pile components, a first mechanical calculation model of the outer pile components in the filling stage is constructed to determine the first mechanical parameters to be calculated for the outer pile components; the first mechanical parameters include the stress conditions of the filling area... The calculations involve considering soil and water pressure, water pressure in the water-facing area, and the first tensile force. Based on the force exerted by the construction equipment on the outer pile assembly, a second mechanical calculation model is constructed for the outer pile assembly during the actual construction phase to determine the second mechanical parameters to be calculated. The second mechanical parameter includes the second tensile force. Based on the anchoring force of the outer pile assembly on the inner pile assembly, a third mechanical calculation model is constructed for the inner pile assembly during the filling phase to determine the third mechanical parameters to be calculated. The third mechanical parameter includes the first tensile force. Based on the force exerted by the construction equipment on the inner pile assembly, a fourth mechanical calculation model is constructed for the inner pile assembly during the actual construction phase to determine the fourth mechanical parameters to be calculated. The fourth mechanical parameter includes the second tensile force.

[0026] Furthermore, it also includes: determining the parameters of the weir core filling, the width of the filling area, the depth of the filling area, and the depth of the water in the upstream area.

[0027] Furthermore, the process of calculating the normal stress and maximum horizontal displacement of the outer and inner pile components based on finite element analysis software and mechanical calculation models of the outer and inner pile components includes: calculating the height of the stable soil core based on the width of the filling area, and inputting the filling parameters of the core within the calculated height range into the finite element analysis software; calculating the displacement of the inner pile component based on the assumed simulated anchor tension and the filling parameters of the core based on the finite element analysis software; calculating the anchor tension stiffness of the inner pile component based on the assumed simulated anchor tension and the displacement of the inner pile component; calculating the normal stress and maximum horizontal displacement of the outer pile component based on the calculated anchor tension stiffness of the inner pile component, and the sum of the first tension and the second tension of the outer pile component during the filling stage and the actual construction stage based on the finite element analysis software; and calculating the normal stress and maximum horizontal displacement of the inner pile component based on the sum of the first tension and the second tension based on the finite element analysis software.

[0028] Furthermore, based on the core filling parameters, filling zone depth, and water depth of the upstream area, the soil and water pressure in the filling zone and the water pressure in the upstream area of ​​the outer pile assembly during the filling stage are calculated sequentially.

[0029] To achieve the above and other related objectives, a third aspect of this application provides a method for constructing a combined cofferdam, comprising:

[0030] Positioning piles were driven on both banks of the river to determine the driving reference lines for the outer and inner pile components.

[0031] Using a pile driver, multiple sheet piles and multiple first steel pipe piles of the outer pile assembly are alternately driven on the pile driving reference line of the outer pile assembly, and the top of the sheet pile is pressed down to maintain a certain distance from the top of the first steel pipe pile.

[0032] Using a pile driver, multiple second steel pipe piles of each inner row of pile components are driven into the pile reference line of the inner row of pile components and inside the first steel pipe pile, while maintaining a distance between adjacent second steel pipe piles.

[0033] Using a crane, the first steel waler of the outer row of pile components and the second steel waler of the inner row of pile components are respectively installed on the outside of the first steel pipe pile and the second steel pipe pile;

[0034] A tie rod assembly corresponding to the inner pile assembly is inserted through the first steel waler and the second steel waler to install the tie rod assembly on the first steel waler and the second steel waler.

[0035] The beneficial effects of the combined cofferdam construction method provided in the third aspect of the present invention are the same as those of the combined cofferdam described above.

[0036] Furthermore, the process of using a crane to install the first steel waler of the outer row of piles and the second steel waler of the inner row of piles on the outside of the first steel pipe pile and the second steel pipe pile includes: welding the first and second bracket plates of the bracket plate assembly to the first and second steel pipe piles respectively; placing the first and second steel walers on the first and second bracket plates respectively; and welding the first and second counter-pressure plates of the counter-pressure plate assembly located above the first and second steel walers to the first and second steel pipe piles respectively.

[0037] Furthermore, the process of installing the tie rods corresponding to the inner pile assembly through the first steel waler and the second steel waler includes: opening through holes in both the first and second steel walers; sequentially passing each tie rod of the tie rod through the through holes in the first and second steel walers to install the tie rod in the first and second steel walers; and sequentially installing anchors of the anchor assembly at both ends of the tie rod to tighten the tie rod.

[0038] Furthermore, the method also includes: backfilling the core soil between the first steel pipe pile and the second steel pipe pile layer by layer until it reaches the height of the stabilized soil in the core; continuing to backfill the core soil between the first steel pipe pile and the second steel pipe pile, and backfilling the core soil between the two rows of second steel pipe piles until it is consistent with the top elevation of the first steel pipe pile and the second steel pipe pile; and laying roadbed steel plates on the top surface of the backfilled core soil to form a working surface for construction equipment to carry out actual construction. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the combined cofferdam structure according to an embodiment of the present invention;

[0040] Figure 2 This is a cross-sectional schematic diagram of a combined cofferdam according to an embodiment of the present invention;

[0041] Figure 3 This is a flowchart illustrating the combined cofferdam calculation method according to an embodiment of the present invention;

[0042] Figure 4 This is a schematic diagram illustrating the design of the water-facing zone and the filling zone of the combined cofferdam according to an embodiment of the present invention.

[0043] Figure 5 This is the first mechanical calculation model of the external pile assembly in the filling stage according to an embodiment of the present invention;

[0044] Figure 6 This is the second mechanical calculation model of the external pile assembly in the actual construction stage of this invention embodiment;

[0045] Figure 7 This is the third mechanical calculation model of the inner pile assembly in the filling stage according to an embodiment of the present invention;

[0046] Figure 8 This is the fourth mechanical calculation model for the internal pile assembly in the actual construction stage of this invention embodiment;

[0047] Figure 9 This is a schematic flowchart of the combined cofferdam construction method according to an embodiment of the present invention;

[0048] Figure 10 This is a schematic diagram of the positioning and laying out of lines according to an embodiment of the present invention;

[0049] Figure 11 This is a schematic diagram of a steel sheet pile and a first steel pipe pile driven into the ground, according to an embodiment of the present invention.

[0050] Figure 12 This is a schematic diagram of a second steel pipe pile driven into the ground, according to an embodiment of the present invention.

[0051] Figure 13 This is a schematic diagram of the welding of a first bracket plate and a second bracket plate according to an embodiment of the present invention;

[0052] Figure 14 This is a schematic diagram of an embodiment of the present invention with a first steel waler and a second steel waler installed;

[0053] Figure 15 This is a schematic diagram of an embodiment of the present invention with a first counter-pressure plate and a second counter-pressure plate installed.

[0054] Figure 16 This is a schematic diagram of the installation of a tie rod according to an embodiment of the present invention;

[0055] Figure 17 This is a schematic diagram of a combined cofferdam with backfilled core soil according to an embodiment of the present invention;

[0056] Figure 18 This is a schematic diagram of a combined cofferdam with a roadbed steel plate laid flat, according to an embodiment of the present invention.

[0057] Figure 19 This is a schematic diagram of the construction equipment of this invention being used in actual construction of a combined cofferdam.

[0058] Component designation explanation

[0059] 1. Outer pile assembly; 11. First steel waler; 12. Steel sheet pile; 13. First steel pipe pile; 2. Inner pile assembly; 21. Second steel waler; 22. Second steel pipe pile; 3. Tie rod; 4. Anchorage; 5. Corbel support plate assembly; 51. First corbel support plate; 52. Second corbel support plate; 6. Counterweight plate assembly; 61. First counterweight plate; 62. Second counterweight plate; 7. Roadbed steel plate; 8. Construction equipment. Detailed Implementation

[0060] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0061] It should be understood that the structures, proportions, sizes, etc., illustrated in the accompanying drawings are merely for illustrative purposes to aid those skilled in the art and are not intended to limit the implementation of the invention. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness and purpose of the invention, should still fall within the scope of the disclosed technical content. The following detailed description should not be considered restrictive, and the scope of the embodiments of this application is limited only by the claims of the published patents. The terminology used herein is for describing specific embodiments only and is not intended to limit the application. Spatial terms such as "upper," "lower," "left," "right," "below," "below," "lower part," "above," "upper part," etc., may be used in the text to illustrate the relationship between one element or feature shown in the figures and another element or feature.

[0062] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," "fixing," and "holding" 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; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0063] Furthermore, as used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context indicates otherwise. It should be further understood that the terms “comprising,” “including,” indicate the presence of the stated feature, operation, element, component, item, kind, and / or group, but do not preclude the presence, occurrence, or addition of one or more other features, operations, elements, components, items, kinds, and / or groups. The terms “or” and “and / or” as used herein are interpreted as inclusive, or mean any one or any combination thereof. Thus, “A, B, or C” or “A, B, and / or C” means “any one of: A; B; C; A and B; A and C; B and C; A, B, and C.” Exceptions to this definition arise only when combinations of elements, functions, or operations are inherently mutually exclusive in some manner.

[0064] like Figure 1 and Figure 2 As shown, an embodiment of the present invention provides a combined cofferdam, comprising: two rows of pile structures forming a stable double-row retaining structure. Each row of pile structures includes: an outer row of pile components 1, multiple sets of inner row of pile components 2, and tie rod components. The multiple sets of inner row of pile components 2 are located inside the outer row of pile components 1. The tie rod components are correspondingly arranged with respect to the inner row of pile components 2.

[0065] The outer pile assembly 1 includes a first steel waler 11, multiple sheet piles 12, and multiple first steel pipe piles 13. The sheet piles 12 and the first steel pipe piles 13 are alternately connected in sequence, with the top of the sheet piles 12 lower than the top of the first steel pipe piles 13. The first steel waler 11 is located on the outside of the multiple first steel pipe piles 13. Each inner pile assembly 2 includes a second steel waler 21 and multiple second steel pipe piles 22. The second steel waler 21 is located on the outside of the multiple second steel pipe piles 22, with adjacent second steel pipe piles 22 spaced apart. The two ends of the tie rod assembly pass through the first steel waler 11 and the second steel waler 21.

[0066] Multiple sheet piles 12 and multiple first steel pipe piles 13 are sequentially and alternately connected, with a first steel waler 11 set on the outside of the multiple first steel pipe piles 13, thus forming an outer pile assembly 1; a second steel waler 21 is set on the outside of multiple second steel pipe piles 22, thus forming an inner pile assembly 2. The multiple sets of inner pile assemblies 2 are discontinuous, and the spacing between adjacent inner pile assemblies 2 can be adjusted. Furthermore, the top of the sheet pile 12 is lower than the top of the first steel pipe pile 13, and adjacent second steel pipe piles 22 are spaced apart, so that the two ends of the tie rod assembly can avoid the sheet piles 12. The first steel waler 11 and the second steel waler 21 are connected by the second steel pipe pile 22. The outer pile assembly 1 and the inner pile assembly 2 form a force-bearing system by anchoring the tie rod assembly. In rivers with deep water, this system can cut off the river and form a stable double-row pile retaining structure. In application scenarios where the riverbank and the cofferdam support piles are not perpendicular, the combined cofferdam of this invention can reasonably avoid the inclined pile positions of the piers to be built when constructing bridge piers in the river channel, providing a dry and convenient construction environment. At the same time, it effectively saves steel consumption and construction costs.

[0067] Specifically, by adjusting the spacing between the outer row of pile components 1 and the inner row of pile components 2, as well as the spacing between adjacent inner row of pile components 2, it is ensured that the inclined pile positions of the piers to be built can be reasonably avoided, providing a dry and convenient construction environment for the pier construction. The spacing between two adjacent sets of inner row of pile components 2 should be set reasonably. If the spacing is too large, fewer inner row of pile components 2 will be arranged, requiring higher rigidity and strength of the tie rod components and the first steel waler 11; if the spacing is too small, more inner row of pile components 2 will be arranged, increasing construction costs.

[0068] like Figure 1 and Figure 2As shown, in some embodiments of the present invention, each tie rod assembly includes multiple tie rods 3. Each tie rod 3 is located between adjacent second steel pipe piles 22. Both the first steel waler 11 and the second steel waler 21 have through holes adapted to the tie rods 3. The tie rods 3 have through holes at both ends to install them onto the first steel waler 11 and the second steel waler 21. By having through holes adapted to the tie rods 3 in the first steel waler 11 and the second steel waler 21, the tie rods 3 pass sequentially through the through holes of the first steel waler 11 and the second steel waler 21. At this time, the tie rods 3 are located between adjacent second steel pipe piles 22, allowing them to bypass the second steel pipe piles 22 and pass through to the outer pile assembly 1. Furthermore, the top of the sheet pile 12 is lower than the top of the first steel pipe pile 13, creating a gap between the top portions of the first steel pipe piles 13. The tie rod 3 can pass through this gap without obstruction, eliminating the need to drill holes in the sheet pile 12 and reducing on-site cutting in actual construction scenarios. For example, each inner row of pile components 2 has three second steel pipe piles 22, which serve as anchor piles. Based on the design scheme, the designed length of the second steel pipe piles 22 is shorter than that of the first steel pipe piles 13, significantly saving material usage and improving economic efficiency. Correspondingly, each tie rod component has two tie rods 3.

[0069] like Figure 1 and Figure 2 As shown, in some embodiments of the present invention, the combined cofferdam further includes anchor assemblies corresponding to the tie rod assemblies. Each anchor assembly includes two pairs of anchors 4, each pair of anchors 4 being respectively fitted onto both ends of the tie rod 3 and located on the outside of the first steel waler 11 and the second steel waler 21. By fitting anchors 4 onto both ends of the tie rod 3, the tie rod 3 passing through the through hole is secured to the first steel waler 11 and the second steel waler 21, thereby tightening the tie rod 3 and improving the overall stability of the combined cofferdam.

[0070] like Figure 1 and Figure 2 As shown, in some embodiments of the present invention, the combined cofferdam further includes a corbel support plate assembly 5. The corbel support plate assembly 5 includes a first corbel support plate 51 and a second corbel support plate 52. The first corbel support plate 51 is fixedly connected to the outside of the first steel pipe pile 13 to support the first steel waler 11; the second corbel support plate 52 is fixedly connected to the outside of the second steel pipe pile 22 to support the second steel waler 21. Specifically, by welding multiple first corbel support plates 51 and second corbel support plates 52 to the outside of the first steel pipe pile 13 and the second steel pipe pile 22 respectively, a stable support is formed, thereby supporting the first steel waler 11 on the first steel pipe pile 13 and the second steel waler 21 on the second steel pipe pile 22 respectively.

[0071] like Figure 1 and Figure 2As shown, in some embodiments of the present invention, the combined cofferdam further includes a counter-pressure plate assembly 6. The counter-pressure plate assembly 6 includes a first counter-pressure plate 61 and a second counter-pressure plate 62. The first counter-pressure plate 61 is fixedly connected to the outside of the first steel pipe pile 13 and located above the first steel waler 11; the second counter-pressure plate 62 is fixedly connected to the outside of the second steel pipe pile 22 and located above the second steel waler 21. Specifically, the first counter-pressure plate 61 is welded at a suitable position on the first steel pipe pile 13 above the first steel waler 11 to form a counter-pressure on the first steel waler 11 for constraint, preventing displacement of the first steel waler 11; and the second counter-pressure plate 62 is welded at a suitable position on the second steel pipe pile 22 above the second steel waler 21 to form a counter-pressure on the second steel waler 21 for constraint, preventing displacement of the second steel waler 21, further enhancing the overall structural stability of the combined cofferdam.

[0072] like Figure 1 As shown, in some embodiments of the present invention, adjacent sheet piles 12 and the first steel pipe pile 13 are detachably connected by a locking mechanism. Specifically, the sheet pile 12 is a Larssen sheet pile, and the first steel pipe pile 13 is a lock-jointed steel pipe pile. The Larssen sheet pile and the lock-jointed steel pipe pile are detachably connected by a locking mechanism. The combination of Larssen sheet piles and lock-jointed steel pipe piles forms the PLC method pile cofferdam structure, which, compared to traditional double-row piles, increases the cross-sectional stiffness and saves on sheet pile material usage.

[0073] Figure 3 This is a flowchart illustrating the combined cofferdam calculation method according to an embodiment of the present invention. The combined cofferdam calculation method according to an embodiment of the present invention includes the following steps:

[0074] Step S31: Based on the construction drawings of the combined cofferdam, the outer area of ​​the outer pile assembly is set as the water-facing area, and the area between the outer pile assembly and the inner pile assembly is set as the filling area.

[0075] like Figure 4 As shown, in step S31, the outer area of ​​the outer pile assembly 1 is designated as the water-facing area, i.e., the outer area of ​​the first steel pipe pile 13 is designated as the water-facing area, bearing the water pressure; the area between the outer pile assembly 1 and the inner pile assembly 2 is designated as the filling area, i.e., backfilling the core soil between the first steel pipe pile 13 and the second steel pipe pile 22 is carried out to ensure structural strength. The outer pile assembly 1 is under stress, forming a retaining and water-blocking structure, which is the main load structure; the three second steel pipe piles 22 at a certain interval in the inner pile assembly 2 and the tie rod 3 form an anchor group, forming the rear anchor pile, forming an anchor structure with a certain rigidity, used to tie the front row, limit deformation and optimize the stress of the pipe pile body. There is a gap between two adjacent sets of inner pile assemblies 2, i.e., a gap is formed between two adjacent sets of inner pile assemblies 2. At the position corresponding to the gap in the outer pile assembly 1, since there is no anchoring effect of the inner pile assembly 2, it is constrained by the rigidity of the first steel waler 11.

[0076] Step S32: Based on the set stress conditions of the outer and inner pile components in the water-facing zone and the filling zone, as well as the stress conditions between the outer and inner pile components, construct a mechanical calculation model for the outer and inner pile components to determine the mechanical parameters to be calculated for the outer and inner pile components.

[0077] In some embodiments of the present invention, the process of constructing a mechanical calculation model of the outer and inner pile components based on the stress conditions of the outer and inner pile components in the set water-facing zone and filling zone, as well as the stress conditions between the outer and inner pile components, to determine the mechanical parameters to be calculated for the outer and inner pile components, includes: dividing the stress stages of the outer and inner pile components into a filling stage and an actual construction stage; constructing a first mechanical calculation model of the outer pile components in the filling stage based on the stress conditions of the outer pile components in the set water-facing zone and filling zone, as well as the anchoring tension of the inner pile components and the tie rod components on the outer pile components, to determine the first mechanical parameters to be calculated for the outer pile components; the first mechanical parameters include the filling... The system calculates the water and soil pressure in the construction area, the water pressure in the water-facing area, and the first tensile force. Based on the force exerted by the construction equipment on the outer pile components, a second mechanical calculation model is constructed for the outer pile components during the actual construction stage to determine the second mechanical parameters to be calculated for the outer pile components. The second mechanical parameter includes the second tensile force. Based on the anchoring tension of the outer pile components on the inner pile components, a third mechanical calculation model is constructed for the inner pile components during the filling stage to determine the third mechanical parameters to be calculated for the inner pile components. The third mechanical parameter includes the first tensile force. Based on the force exerted by the construction equipment on the inner pile components, a fourth mechanical calculation model is constructed for the inner pile components during the actual construction stage to determine the fourth mechanical parameters to be calculated for the inner pile components. The fourth mechanical parameter includes the second tensile force.

[0078] like Figure 4 and Figure 5 As shown, the outer pile assembly 1 constructs a first mechanical calculation model during the filling stage. During this stage, the outer pile assembly 1 is subjected to filling soil pressure and deforms towards the water-facing side. The inner pile assembly 2 restricts the deformation of the outer pile assembly 1 through tie rods 3. Based on the defined filling area, the filling soil and water pressure of the riverbed filling area on the first steel pipe pile 13 of the outer pile assembly 1 is determined. Based on the established water-facing zone, determine the water pressure of the riverbed surface on the first steel pipe pile 13 in the water-facing zone. Furthermore, based on the anchoring force of the inner pile assembly 2 and the tie rod 3 of the tie rod assembly on the outer pile assembly 1, the first tensile force on the outer pile assembly 1 is determined. Thus, the first mechanical parameter to be calculated for the outer pile component 1 during the filling stage is determined.

[0079] like Figure 4 and Figure 6 As shown, the second mechanical calculation model of the external pile assembly 1 during the actual construction stage is presented. The external pile assembly 1 mainly bears the second tensile force generated by the load of the construction equipment. Therefore, the second mechanical parameter to be calculated for the external pile assembly 1 during the actual construction phase is determined. In addition, the external pile assembly 1 also bears the pressure generated by the load of the construction equipment itself. This article does not perform specific calculations; calculations can be made based on the actual construction equipment.

[0080] like Figure 4 and Figure 7 As shown, during the filling stage, the inner pile assembly 2 constructs a third mechanical calculation model. Based on the anchoring force of the outer pile assembly 1 on the inner pile assembly 2, it is determined that the inner pile assembly 2 is subjected to the first tensile force. Thus, the third mechanical parameter to be calculated for the inner pile assembly 2 during the filling stage is determined.

[0081] like Figure 4 and Figure 8 As shown, the fourth mechanical calculation model of the inner pile assembly 2 in the actual construction stage is presented. The inner pile assembly 2 mainly bears the second tensile force generated by the load of the construction equipment. Therefore, the fourth mechanical parameter to be calculated for the inner pile assembly 2 during the actual construction stage is determined. It should be noted that this paper only considers the magnitude of the force, not the direction. Step S33: Based on the finite element analysis software and combined with the mechanical calculation models of the outer and inner pile assemblies, the normal stress value and maximum horizontal displacement value of the outer and inner pile assemblies are calculated respectively.

[0082] Step S34: Verify whether the calculated normal stress values ​​and maximum horizontal displacement values ​​of the outer and inner pile components meet the preset requirements of the outer and inner pile components; if both the outer and inner pile components meet the preset requirements, then proceed with construction based on the construction drawings of the combined cofferdam; if either the outer or inner pile component does not meet the preset requirements, then redesign the construction drawings.

[0083] By using mechanical calculation models of the outer pile assembly 1 and inner pile assembly 2 during the filling stage, the distribution of soil and water pressure and the anchor tension transmission mechanism are clearly defined. Based on the final calculation results, the pile spacing, pile length, and prestress of the tie rod 3 can be adjusted accordingly, avoiding problems such as material waste or insufficient strength compared to traditional experience-based design. Simultaneously, by using mechanical calculation models of the outer pile assembly 1 and inner pile assembly 2 during the actual construction stage, combined with finite element analysis software to quantify the tension of construction equipment on the cofferdam, real-time early warning can be achieved. If the cofferdam strength exceeds the limit, construction should be stopped and reinforcement should be carried out.

[0084] In some embodiments of the present invention, the combined cofferdam calculation method further includes: determining the core filling parameters, the width of the filling area, the depth of the filling area, and the water depth of the water-facing area within the filling area.

[0085] Specifically, based on the construction area, the parameters of the weir core fill are provided within that area. These parameters include the unit weight of the fill soil. The density of water Cohesion of fill soil Internal friction angle of the weir core fill Active earth pressure coefficient .

[0086] like Figure 5 and Figure 6 As shown, the depth of the filling area is determined based on the design drawings. This refers to the depth of the core soil of the weir from the riverbed surface during the filling process in the embankment area; the depth of the water in the upstream area is determined based on actual measurements of the area where the bridge piers are to be built. .

[0087] like Figure 5 and Figure 7 As shown, the width of the filling area is determined based on the design drawings of the actual project. That is, the distance between the first steel pipe pile 13 and the second steel pipe pile 22 is .

[0088] In some embodiments of the present invention, the process of calculating the normal stress and maximum horizontal displacement of the outer and inner pile components based on finite element analysis software and mechanical calculation models of the outer and inner pile components includes: calculating the height of the stable soil core based on the width of the filling area, and inputting the filling parameters of the core within the calculated height range into the finite element analysis software; calculating the displacement of the inner pile component based on the assumed simulated anchor tension and the filling parameters of the core based on the finite element analysis software; calculating the anchor tension stiffness of the inner pile component based on the assumed simulated anchor tension and the displacement of the inner pile component; calculating the normal stress and maximum horizontal displacement of the outer pile component based on the calculated anchor tension stiffness of the inner pile component, and the sum of the first tension and the second tension of the outer pile component during the filling stage and the actual construction stage based on the finite element analysis software; and calculating the normal stress and maximum horizontal displacement of the inner pile component based on the sum of the first tension and the second tension based on the finite element analysis software. For example, the finite element analysis software used is the Qimingxing simulation software.

[0089] like Figure 4 and Figure 7As shown, backfilling is carried out on the side of the second steel pipe pile 22. The backfilled core soil has a restraining effect on the second steel pipe pile 22. Based on the passive earth pressure rupture angle and considering the restraining effect of the core soil on the second steel pipe pile 22, the height of the stable core soil is calculated. Therefore, the height of the soil spring due to the constraint effect of the soil core is calculated, and the specific calculation formula is as follows:

[0090] ;Formula (1)

[0091] in, The height of the stabilizing soil in the weir core; The distance between the first steel pipe pile and the second steel pipe pile; The internal friction angle of the weir core fill soil.

[0092] The height of the stabilized soil in the weir core was obtained through calculation. ,Will Unit weight of fill soil within the range Cohesion of fill soil Internal friction angle of the weir core fill Input into the finite element analysis software, and... The specific gravity of water within the range Input into the finite element analysis software; the prestressing module of the finite element analysis software is used to simulate the anchor tension. The displacement of the inner pile assembly 2 was calculated. The anchoring stiffness of the inner pile assembly 2 was further calculated. The specific calculation formula is as follows:

[0093] ;Formula (2)

[0094] For example, suppose we simulate anchor tension. Given a value of 100 kN / m, calculate the displacement. The anchor tension is calculated from 75mm. is 100 / 0.075=1333kN / m2=1.33MN / m2.

[0095] The anchoring stiffness calculated according to formula (2) and the unit weight of the fill soil input. Cohesion of fill soil Internal friction angle of the weir core fill Based on the PLC / PC method pile calculation module of the finite element analysis software, the normal stress value and maximum horizontal displacement value of the first steel pipe pile 13 of the outer pile assembly 1 are calculated by applying loads. That is, the finite element analysis software directly outputs the normal stress value and maximum horizontal displacement value of the first steel pipe pile 13. The calculated normal stress value and maximum horizontal displacement value are compared with the preset requirements of the outer pile assembly 1 to determine whether they meet the requirements. Simultaneously, the finite element analysis software calculates the sum of the first tensile force and the second tensile force of the outer pile assembly 1 during the filling stage and the actual construction stage. Further, based on the calculated sum of the first tensile force and the second tensile force on the outer pile assembly 1, the normal stress value and maximum horizontal displacement value of the inner pile assembly 2 are calculated using the finite element analysis software. For example, based on the anchor stiffness calculated above... Finite element analysis software calculated the normal stress value of the first steel pipe pile 13 to be 71 MPa, which is less than the limit of 305 MPa for steel piles and meets the preset requirements; and the maximum horizontal displacement value is 36.7 mm, which is less than the conventional limit of 40 mm for cofferdams and meets the preset requirements. Simultaneously, the first tensile force experienced by the outer pile assembly 1 during the filling stage and the actual construction stage was calculated. Second tension sum It is 24.6 kN / m. This was obtained through calculation. The stress was calculated to be 24.6 kN / m. Further calculations showed that the normal stress of the second steel pipe pile 22 in the inner pile assembly 2 was 81 MPa, less than the steel pile limit of 305 MPa, meeting the preset requirements; and the maximum horizontal displacement was 36.9 mm, less than the conventional cofferdam limit of 40 mm, also meeting the preset requirements. Simultaneously, the calculated maximum horizontal displacement of the first steel pipe pile 13 (36.7 mm) and the maximum horizontal displacement of the second steel pipe pile 22 (36.9 mm) were compared to verify the structural accuracy of the combined cofferdam through deformation coordination. The anchor tension of the inner pile assembly 2 and the outer pile assembly 1 was also measured. Closed-loop calculations were used to verify the collaborative performance of the combined cofferdam. In some embodiments of the present invention, based on the core filling parameters, the filling zone depth, and the water depth of the upstream area, the soil and water pressure in the filling zone and the water pressure in the upstream area of ​​the outer pile assembly during the filling stage were calculated sequentially.

[0096] like Figure 4 and Figure 5 As shown, the external pile assembly 1 experiences water and soil pressure in the filling area during the filling stage. The specific calculation formula is as follows:

[0097] ;Formula (3)

[0098] in, The active earth pressure coefficient is calculated using the following formula:

[0099] ;Formula (4)

[0100] in, The internal friction angle of the fill soil in the weir core; The unit weight of the fill soil; The specific gravity of water; The cohesion of the fill soil; This refers to the depth of the filling area.

[0101] Water pressure in the upstream zone experienced by external pile assembly 1 during the filling stage The specific calculation formula is as follows:

[0102] ;Formula (5)

[0103] in, The specific gravity of water; This refers to the depth of the water in the water-facing area.

[0104] If the calculated normal stress and maximum horizontal displacement values ​​of the first steel pipe pile 13 and the second steel pipe pile 22 meet the preset requirements through the above-mentioned combined cofferdam calculation method, it can also verify that the designed spacing between the first steel pipe pile 13 and the second steel pipe pile 22 meets the construction requirements, thereby ensuring that the outer pile assembly 1 and the inner pile assembly 2 can reasonably avoid the inclined arrangement of the pier piles to be built and meet the construction requirements.

[0105] Furthermore, the anchor tension F calculated using the aforementioned combined cofferdam calculation method can be used to verify the shear and bending strength of the first steel waler 11 and the second steel waler 21 as a multi-span continuous beam, thereby determining the appropriate models of the first steel waler 11 and the second steel waler 21; and the design value of the tension of the tie rod 3 can be calculated using the anchor tension F and the spacing of the tie rod 3, and the diameter of the tie rod can be determined using the tensile strength of the tie rod 3, thereby determining the specifications of each component of the entire combined cofferdam.

[0106] Figure 9 This is a schematic flowchart of a combined cofferdam construction method according to an embodiment of the present invention. The combined cofferdam construction method according to an embodiment of the present invention includes the following steps:

[0107] Step S91: Drive positioning piles on both banks of the river and lay out the positioning lines to determine the driving reference lines for the outer row of pile components and the inner row of pile components respectively.

[0108] like Figure 1 and Figure 10 As shown, positioning piles are driven on both banks of the construction river based on the construction drawings of the combined cofferdam, so as to determine the specific construction locations of the outer pile component 1 and the inner pile component 2, and mark the pile driving reference lines of the outer pile component 1 and the inner pile component 2.

[0109] Step S92: Using a pile driver, alternately drive multiple sheet piles and multiple first steel pipe piles of the outer pile assembly along the pile driving reference line of the outer pile assembly, and press down the top of the sheet piles to maintain a certain distance from the top of the first steel pipe piles.

[0110] like Figure 1 and Figure 11 As shown, the outer pile assembly 1 is constructed along the piling reference line. For example, the first steel pipe pile 13 is driven first, followed by the steel sheet pile 12. The steel sheet pile 12 and the first steel pipe pile 13 are connected by a locking mechanism. When driving the steel sheet pile 12, it is pressed down so that its top is 1 meter lower than the top of the first steel pipe pile 13. This ensures that the tie rod 3 can avoid the steel sheet pile 12 penetrating the first steel waler 11, reducing the amount of cutting required on site.

[0111] Step S93: Using a pile driver, drive multiple second steel pipe piles of each inner row of pile components on the pile driving reference line of the inner row of pile components and inside the first steel pipe pile, while maintaining a distance between adjacent second steel pipe piles.

[0112] like Figure 1 and Figure 12 As shown, the inner pile assembly 2 is driven on the pile driving reference line of the inner pile assembly 2, and the second steel pipe pile 22 is driven in. Three second steel pipe piles 22 form a group of inner pile assembly 2, and the distance between adjacent second steel pipe piles 22 is 1.1 meters to ensure that the tie rod 3 can pass through the second steel pipe pile 22 to the outer pile assembly 1.

[0113] Step S94: Using a crane, install the first steel waler of the outer row pile assembly and the second steel waler of the inner row pile assembly on the outside of the first steel pipe pile and the second steel pipe pile, respectively.

[0114] In some embodiments of the present invention, the process of using a crane to install the first steel waler of the outer row pile assembly and the second steel waler of the inner row pile assembly on the outside of the first steel pipe pile and the second steel pipe pile respectively includes: welding the first and second bracket plates of the bracket plate assembly to the first and second steel pipe piles respectively; placing the first and second steel walers on the first and second bracket plates respectively; and welding the first and second counter-pressure plates of the counter-pressure plate assembly located above the first and second steel walers to the first and second steel pipe piles respectively.

[0115] like Figure 1 , Figure 2 and Figure 13As shown, the bracket support assembly 5 is welded. Specifically, multiple first bracket supports 51 are welded to the outside of the first steel pipe pile 13 based on the designed positions, and multiple second bracket supports 52 are welded to the outside of the second steel pipe pile 22 based on the designed positions, with a gap maintained between adjacent first bracket supports 51 or second bracket supports 52. For example, the spacing between adjacent first bracket supports 51 or second bracket supports 52 is 2.2 meters, and the number of first bracket supports 51 and second bracket supports 52 welded on the first steel waler 11 and the second steel waler 21 is appropriate to provide sufficient support. It should be noted that the outside of the first steel pipe pile 13 is the water-facing side, and the outside of the second steel pipe pile 22 is also the water-facing side.

[0116] like Figure 1 , Figure 2 and Figure 14 As shown, a first steel waler 11 and a second steel waler 21 are installed. Specifically, the first steel waler 11 is placed on a plurality of welded first bracket plates 51; the second steel waler 21 is placed on a plurality of welded second bracket plates 52. The first steel waler 11 and the second steel waler 21 integrate force, transfer load, and control deformation to ensure the overall stability of the outer pile assembly 1 and the inner pile assembly 2.

[0117] like Figure 1 , Figure 2 and Figure 15 As shown, the welding of the counter-pressure plate assembly 6 is performed. Specifically, the first counter-pressure plate 61 is welded to the position of the first steel pipe pile 13 above the already installed first steel waler 11; and the second counter-pressure plate 62 is welded to the position of the second steel pipe pile 22 above the already installed second steel waler 21. The first counter-pressure plate 61 and the second counter-pressure plate 62 respectively limit the first steel waler 11 and the second steel waler 21, preventing slippage and ensuring the stability of the first steel waler 11 and the second steel waler 21.

[0118] Step S95: Insert the tie rod assembly corresponding to the inner pile assembly through the first steel waler and the second steel waler to install the tie rod assembly on the first steel waler and the second steel waler.

[0119] In some embodiments of the present invention, the process of installing the tie rods corresponding to the inner pile assembly through the first steel waler and the second steel waler includes: opening through holes in both the first steel waler and the second steel waler; sequentially passing each tie rod of the tie rod through the through holes in the first steel waler and the second steel waler to install the tie rod in the first steel waler and the second steel waler; and sequentially installing anchors of the anchor assembly at both ends of the tie rod to tighten the tie rod.

[0120] like Figure 1 and Figure 16 As shown, the tie rod assembly is installed. Specifically, one end of the tie rod 3 is sequentially passed through the through holes of the first steel waler 11 and the second steel waler 21 until it exits through the through hole of the second steel waler 21. Then, anchors 4 are installed at both ends of the tie rod 3 to secure it to the first steel waler 11 and the second steel waler 21, forming a stable double-row force-bearing system. The above steps are repeated to install the tie rods 3 one by one, and the tie rods 3 are installed at the top of the sheet pile 12 to avoid drilling holes in the sheet pile 12 and reduce material waste.

[0121] In some embodiments of the present invention, the construction method further includes: backfilling the core soil between the first steel pipe pile and the second steel pipe pile layer by layer until the height of the stabilized soil in the core is reached; continuing to backfill the core soil between the first steel pipe pile and the second steel pipe pile, and backfilling the core soil between the two rows of the second steel pipe pile until it is consistent with the top elevation of the first steel pipe pile and the second steel pipe pile; and laying roadbed steel plates on the top surface of the backfilled core soil to form a working surface for construction equipment to carry out actual construction.

[0122] like Figure 1 , Figure 17 and Figure 18 As shown, after the composite cofferdam structure is installed, the core soil is backfilled between the first steel pipe pile 13 and the second steel pipe pile 22 until the height of the stabilized core soil is reached. Continue backfilling the core soil in the filling area, and backfill the core soil between the two rows of second steel pipe piles 22 to ensure that the backfilled core soil has a certain degree of compaction and forms a stable double-row system until the backfilling reaches the same elevation as the first steel pipe pile 13 and the second steel pipe pile 22; lay the roadbed steel plate 7 on the top surface of the backfilled core soil to form a mechanical working surface so that the construction equipment 8 can carry out the construction of the pier to be built on the roadbed steel plate 7.

[0123] In summary, addressing the technical problem that existing technologies cannot reasonably avoid the location of the main bridge piers, thus preventing pier construction, this invention provides a combined cofferdam, calculation method, and construction method. This method involves the sequential alternating connection of multiple sheet piles and multiple first steel pipe piles. First steel walers are positioned outside the multiple first steel pipe piles, forming an outer pile assembly. Second steel walers are positioned outside the multiple second steel pipe piles, forming an inner pile assembly. The tops of the sheet piles are lower than the tops of the first steel pipe piles, and adjacent second steel pipe piles are spaced apart, allowing the ends of the tie rod assembly to penetrate through both the first and second steel walers. The outer and inner pile assemblies are connected by the tie rod assembly. The anchoring system forms a load-bearing system, enabling stable double-row pile retaining structures to be formed by damming the river in deep waters. Furthermore, in applications where the riverbank and cofferdam support piles are not perpendicular, the combined cofferdam of this invention can reasonably avoid the inclined pile positions of the piers to be built when constructing bridge piers in the river channel, providing a dry and convenient construction environment, effectively saving steel and construction costs. The calculation method for the combined cofferdam provided by this invention improves the calculation theory of double-row cofferdam structures, fully calculating the structural stability, overturning resistance, and tensile stress states of the double-row cofferdam structure, enabling accurate simulation for subsequent actual construction and ensuring the safety of actual construction. Therefore, this invention effectively overcomes the various shortcomings of existing technologies and has high industrial application value.

[0124] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A composite cofferdam, characterized in that, include: The structure consists of two rows of piles, each row including: The external pile assembly includes a first steel waler, multiple steel sheet piles, and multiple first steel pipe piles. The multiple steel sheet piles and the multiple first steel pipe piles are connected alternately in sequence, and the top of the steel sheet piles is lower than the top of the first steel pipe piles. The first steel waler is disposed on the outside of the multiple first steel pipe piles. Multiple sets of inner pile components are located inside the outer pile components, and a gap is formed between two adjacent sets of inner pile components; the spacing between the outer pile components and the inner pile components is adjustable, as is the spacing between adjacent inner pile components; each set of inner pile components includes a second steel waler and multiple second steel pipe piles, the second steel waler is disposed outside the multiple second steel pipe piles, and adjacent second steel pipe piles are spaced apart; A tie rod assembly is provided corresponding to the inner pile assembly, with both ends of the tie rod assembly passing through the first steel waler and the second steel waler.

2. The combined cofferdam according to claim 1, characterized in that, Each set of tie rod assemblies includes multiple tie rods, each tie rod being located between adjacent second steel pipe piles; both the first steel waler and the second steel waler are provided with through holes adapted to the tie rods, and both ends of the tie rods pass through the through holes to install the tie rods onto the first steel waler and the second steel waler.

3. The combined cofferdam according to claim 2, characterized in that, It also includes anchor assemblies corresponding to the tie rod assembly. Each set of anchor assemblies includes two pairs of anchors. Each pair of anchors is respectively sleeved on both ends of the tie rod and located on the outside of the first steel waler and the second steel waler.

4. The combined cofferdam according to claim 1, characterized in that, It also includes a corbel support plate assembly, which includes a first corbel support plate and a second corbel support plate. The first corbel support plate is fixedly connected to the outside of the first steel pipe pile and is used to support the first steel waler. The second corbel support plate is fixedly connected to the outside of the second steel pipe pile and is used to support the second steel waler.

5. The combined cofferdam according to claim 1, characterized in that, It also includes a counter-pressure plate assembly, which includes a first counter-pressure plate and a second counter-pressure plate. The first counter-pressure plate is fixedly connected to the outside of the first steel pipe pile and is located above the first steel waler; the second counter-pressure plate is fixedly connected to the outside of the second steel pipe pile and is located above the second steel waler.

6. The combined cofferdam according to claim 1, characterized in that, The adjacent sheet piles are detachably connected to the first steel pipe pile via a locking mechanism.

7. A calculation method for a combined cofferdam as described in any one of claims 1 to 6, characterized in that, include: Based on the construction drawings of the combined cofferdam, the outer area of ​​the outer pile assembly is designated as the water-facing area, and the area between the outer pile assembly and the inner pile assembly is designated as the filling area. Based on the stress conditions of the outer and inner pile components in the water-facing and filling areas, as well as the stress conditions between the outer and inner pile components, mechanical calculation models of the outer and inner pile components are constructed to determine the mechanical parameters to be calculated for the outer and inner pile components. Based on finite element analysis software and combined with the mechanical calculation models of the outer and inner pile components, the normal stress and maximum horizontal displacement values ​​of the outer and inner pile components were calculated respectively. Verify whether the calculated normal stress and maximum horizontal displacement values ​​of the outer and inner pile components meet the preset requirements of the outer and inner pile components. If both the outer and inner pile components meet the preset requirements, construction shall be carried out based on the construction drawings of the combined cofferdam. If either the outer or inner pile component does not meet the preset requirements, the construction drawings shall be redesigned.

8. The calculation method according to claim 7, characterized in that, Based on the stress conditions of the outer and inner pile components in the designated water-facing and filling areas, as well as the stress conditions between the outer and inner pile components, a mechanical calculation model of the outer and inner pile components is constructed to determine the mechanical parameters to be calculated for the outer and inner pile components. This process includes: The stress-bearing stages of the outer pile assembly and the rear pile assembly are divided into the filling stage and the actual construction stage. Based on the stress conditions of the outer pile components in the water-facing zone and the filling zone, as well as the anchoring tension of the inner pile components and the tie rod components on the outer pile components, a first mechanical calculation model of the outer pile components during the filling stage is constructed to determine the first mechanical parameters to be calculated for the outer pile components. The first mechanical parameters include the soil and water pressure in the filling zone, the water pressure in the water-facing zone, and the first tension. Based on the force exerted by the construction equipment on the outer pile assembly, a second mechanical calculation model of the outer pile assembly in the actual construction stage is constructed to determine the second mechanical parameters to be calculated for the outer pile assembly; the second mechanical parameter includes the second tensile force. Based on the anchoring force of the outer pile assembly to the inner pile assembly, a third mechanical calculation model of the inner pile assembly during the filling stage is constructed to determine the third mechanical parameters to be calculated for the inner pile assembly; the third mechanical parameters include the first tension. Based on the force exerted by the construction equipment on the inner pile assembly, a fourth mechanical calculation model of the inner pile assembly in the actual construction stage is constructed to determine the fourth mechanical parameter to be calculated for the inner pile assembly; the fourth mechanical parameter includes the second tensile force.

9. The calculation method according to claim 8, characterized in that, Also includes: The parameters of the weir core fill, the width and depth of the filling area, and the water depth of the upstream area are determined within the filling zone. Based on finite element analysis software and combined with mechanical calculation models of the outer and inner pile components, the normal stress and maximum horizontal displacement values ​​of the outer and inner pile components are calculated respectively. The process includes: The height of the stabilized soil in the core of the weir is calculated based on the width of the filling area, and the filling parameters of the core within the calculated height range are input into the finite element analysis software. Based on the finite element analysis software, assuming simulated anchor tension, and combined with the weir core filling parameters, the displacement of the inner pile assembly is calculated. The anchoring stiffness of the inner pile assembly is calculated based on the assumed simulated anchoring force and the displacement of the inner pile assembly. Based on the anchoring stiffness of the inner pile assembly calculated using finite element analysis software, the normal stress and maximum horizontal displacement of the outer pile assembly are calculated, as well as the sum of the first and second tensile forces of the outer pile assembly during the filling stage and the actual construction stage. Based on the sum of the first and second tensile forces, the normal stress and maximum horizontal displacement of the inner pile assembly are calculated using finite element analysis software.

10. The calculation method according to claim 9, characterized in that, Based on the core filling parameters, filling zone depth, and water depth of the upstream area, the soil and water pressure in the filling zone and the water pressure in the upstream area of ​​the outer pile assembly during the filling stage are calculated sequentially.

11. A construction method for a combined cofferdam as described in any one of claims 1 to 6, characterized in that, include: Positioning piles were driven on both banks of the river to determine the driving reference lines for the outer and inner pile components. Using a pile driver, multiple sheet piles and multiple first steel pipe piles of the outer pile assembly are alternately driven on the pile driving reference line of the outer pile assembly, and the top of the sheet pile is pressed down to maintain a certain distance from the top of the first steel pipe pile. Using a pile driver, multiple second steel pipe piles of each inner row of pile components are driven into the pile reference line of the inner row of pile components and inside the first steel pipe pile, while maintaining a distance between adjacent second steel pipe piles. Using a crane, the first steel waler of the outer row of pile components and the second steel waler of the inner row of pile components are respectively installed on the outside of the first steel pipe pile and the second steel pipe pile; A tie rod assembly corresponding to the inner pile assembly is inserted through the first steel waler and the second steel waler to install the tie rod assembly on the first steel waler and the second steel waler.

12. The construction method according to claim 11, characterized in that, The process of using a crane to install the first steel waler of the outer pile assembly and the second steel waler of the inner pile assembly on the outside of the first steel pipe pile and the second steel pipe pile, respectively, includes: The first and second bracket plates of the bracket assembly are welded onto the first and second steel pipe piles, respectively. The first steel waler and the second steel waler are respectively placed on the first bracket plate and the second bracket plate; The first and second counter-pressure plates of the counter-pressure plate assembly located above the first and second steel walers are respectively welded to the first and second steel pipe piles.

13. The construction method according to claim 12, characterized in that, The process of installing the tie rod assembly corresponding to the inner pile assembly through the first steel waler and the second steel waler includes: Through holes are made in both the first steel waler and the second steel waler. Each tie rod of the tie assembly is sequentially passed through the through holes in the first steel waler and the second steel waler to install the tie rod in the first steel waler and the second steel waler. Anchors of the anchor assembly are installed sequentially at both ends of the tie rod to tighten the tie rod.

14. The construction method according to claim 13, characterized in that, Also includes: Backfill the core soil between the first steel pipe pile and the second steel pipe pile layer by layer until the core soil reaches the height of the stabilized soil body. Continue backfilling the core soil between the first steel pipe pile and the second steel pipe pile, and backfill the core soil between the two rows of second steel pipe piles until it is consistent with the top elevation of the first steel pipe pile and the second steel pipe pile; A roadbed steel plate is laid flat on the top surface of the backfilled core soil to form a working surface for construction equipment to carry out actual construction.

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