An adjustable cofferdam structure and a cofferdam construction method

Abstract

The application provides an adjustable cofferdam structure and a cofferdam construction method. The cofferdam structure comprises two pile foundations and a brace arranged between the two pile foundations. The length of each pile foundation is adjustable; the pile foundation is used for being inserted into a foundation to fix the cofferdam structure and is adjusted to a predetermined length according to soil quality; the brace is fixedly connected between the two pile foundations, the length of the brace is adjustable, and the brace and the pile foundation are fixedly connected through a coaming; and a cofferdam filling area is formed between two adjacent pile foundations. The application provides an adjustable cofferdam structure and a cofferdam construction method, the length and width of the cofferdam structure can be adjusted to adapt to various geological conditions, meet various engineering requirements, and increase the versatility of the cofferdam.

Description

Technical Field

[0001] This application relates to the field of water conservancy and hydropower construction technology, and more specifically, to an adjustable cofferdam structure and a cofferdam construction method. Background Technology

[0002] Common cofferdam structures in water conservancy and hydropower projects include earth-rock cofferdams, sheet pile cofferdams, and steel pipe pile cofferdams. In many small-scale projects, earth-rock cofferdams are relatively simple in construction and lower in cost. However, in actual projects, due to limitations and considerations regarding the project scope, navigation requirements, and protection of adjacent structures, cofferdams such as steel pipe pile cofferdams, which are relatively more expensive but offer better safety and stability, are often the only viable option. Furthermore, in some projects with complex and variable geological conditions, the geological and topographical parameters obtained from the preliminary design survey may differ from the actual situation. This means that a cofferdam that meets the design requirements may not be able to adapt to the actual site environment and fully meet the safety and stability requirements.

[0003] Therefore, how to provide a cofferdam that meets the requirements of environmentally friendly and civilized construction, meets the actual needs of general engineering projects, has a relatively low cost, is technically feasible, has a simple structure, and is highly versatile has become a hot research topic. Summary of the Invention

[0004] The purpose of this application is to provide an adjustable cofferdam structure and cofferdam construction method, which can adjust the length and width of the cofferdam according to needs to meet various engineering requirements.

[0005] Firstly, an adjustable cofferdam structure is provided, comprising two pile foundations and a bracing structure between the two pile foundations.

[0006] The length of each pile foundation is adjustable; the pile foundation is used to be inserted into the foundation to fix the cofferdam structure, and can be adjusted to a predetermined length according to the soil conditions; the bracing is fixedly connected between two pile foundations, the length of the bracing is adjustable, and the bracing is fixedly connected to the pile foundation by walers; a cofferdam filling area is formed between two adjacent pile foundations.

[0007] In one feasible embodiment, both the pile foundation and the bracing are multi-stage expansion structures.

[0008] In one feasible embodiment, the pile foundation includes a primary foundation, a secondary foundation, and a tertiary foundation; the primary foundation and the secondary foundation are both hollow cylinders with open bottoms, the secondary foundation is coaxially fitted inside the primary foundation, and the tertiary foundation is coaxially fitted inside the secondary foundation.

[0009] In one feasible embodiment, the outer surfaces of the primary substrate, the secondary substrate, and the tertiary substrate are all provided with external threads.

[0010] In one feasible embodiment, a second elastic element is provided on the top of the secondary substrate, and a third elastic element is provided on the top of the tertiary substrate; a first through hole is provided at the bottom of the primary substrate, and a second through hole is provided at the bottom of the secondary substrate; the first through hole is used to limit the second elastic element after it extends out, and the second through hole is used to limit the third elastic element after it extends out.

[0011] In one feasible embodiment, a strip-shaped buffer layer is affixed to the inner wall of the primary substrate and the secondary substrate, the length of the strip-shaped buffer layer being the length from the second elastic element to the first through hole.

[0012] In one feasible approach, multiple pads are placed at the bottom of both the primary and secondary substrates.

[0013] In one feasible embodiment, a tapered drill bit is provided at the bottom of the tertiary substrate, the diameter of the tapered drill bit being 1.5-2 times the diameter of the primary substrate; the tapered drill bit is detachably connected to the bottom of the tertiary substrate via an external thread.

[0014] In one feasible embodiment, the bracing is a two-stage telescopic cylindrical structure, comprising a primary bracing and a secondary bracing, wherein the secondary bracing is fitted inside the primary bracing;

[0015] Multiple bracing buckles are provided at the insertion end of the secondary bracing, and multiple buttons are provided at the extension end of the secondary bracing. The bracing buckles and the buttons are inserted into the secondary bracing along the radial direction of the secondary bracing. The insertion ends of the bracing buckles and the insertion ends of the buttons are connected by a connecting plate.

[0016] Multiple pre-drilled holes are arranged on the side wall of the first-level support along the sliding direction of the support buckle. The pre-drilled holes are used for the support buckle to extend and limit the support buckle.

[0017] According to a second aspect of this application, an adjustable cofferdam construction method is also provided, using the adjustable cofferdam structure provided in the first aspect, comprising the following steps:

[0018] S1. Drill holes and conduct geological surveys on the soil at the project site to obtain soil layer parameters, determine the topographic and geological parameters based on the soil layer parameters, and determine the length of the primary base and the length of the primary support based on the topographic and geological parameters.

[0019] S2. When the actual geological conditions are worse than the topographic geological parameters, adjust the length of the pile foundation until the safety and stability requirements are met, and drive the adjusted pile foundation into the soil.

[0020] S3. After driving the piles to the design elevation, install bracing between two adjacent piles.

[0021] S4. Backfill soil in the cofferdam filling area between the pile foundations;

[0022] S5. After the project is completed, the pile foundation and bracing will be dismantled and recycled.

[0023] Compared with the prior art, the beneficial effects of this application are as follows:

[0024] In the technical solution of this application, when the second or third elastic element extends, the bonding friction between the pile foundation and the soil is enhanced, thereby enhancing the overturning resistance of the cofferdam and improving its stability.

[0025] By setting external threads on the surface of the pile foundation, the bonding friction with the soil can be enhanced, thereby increasing the overturning resistance of the cofferdam and improving its stability.

[0026] By setting adjustable-length bracing, the stability and safety of the cofferdam can be enhanced, meeting the requirements of actual engineering projects.

[0027] By setting the diameter and length of each stage of the foundation in a multi-section pile foundation structure to decrease sequentially, compared with steel pipe pile cofferdams of equal length and diameter, it can adapt to various engineering needs, has universality, and saves more material weight and costs.

[0028] The use of a conical drill bit helps the pile foundation to penetrate more easily into hard strata when constructing a cofferdam.

[0029] This application provides an adjustable cofferdam structure and a cofferdam construction method. The length and width of the cofferdam structure can be adjusted to adapt to various geological conditions, meet various engineering needs, and increase the versatility of the cofferdam. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the adjustable cofferdam structure according to an embodiment of the present invention.

[0031] Figure 2 This is a front view of the pile foundation in the contracted state of the adjustable cofferdam structure according to an embodiment of the present invention.

[0032] Figure 3 This is a front view of the pile foundation in the unfolded state of the adjustable cofferdam structure according to an embodiment of the present invention.

[0033] Figure 4 This is a top view of the pile foundation in the contracted state of the adjustable cofferdam structure according to an embodiment of the present invention.

[0034] Figure 5 This is a top view of the adjustable cofferdam structure of this invention, showing only the pile foundation of the secondary base.

[0035] Figure 6 This is a schematic diagram of the second elastic element in the deployed state in the adjustable cofferdam structure of this invention.

[0036] Figure 7 This is a schematic diagram of the second elastic element in the compressed state in the adjustable cofferdam structure of this invention.

[0037] Figure 8 This is a schematic diagram of the connection between the conical drill bit and the three-stage base in the adjustable cofferdam structure of this invention.

[0038] Figure 9 This is a front view of the adjustable cofferdam structure in the embodiment of the present invention, with the support in the contracted state.

[0039] Figure 10 This is a schematic diagram of the adjustable cofferdam structure according to an embodiment of the present invention, showing the secondary bracing in different states within the primary bracing.

[0040] The reference numerals in the attached figures are explained as follows:

[0041] 1. Pile foundation; 2. Bracing; 3. Backfill; 4. Waler; 5. Water body; 6. Foundation; 101. Primary foundation; 102. External thread; 103. Secondary elastic element; 104. Pad; 105. Secondary foundation; 106. Tertiary foundation; 107. Tapered drill bit; 108. First through hole; 109. Strip buffer layer; 110. Connecting edge; 111. Threaded section; 201. Secondary bracing; 202. Button; 203. Bracing buckle; 204. Primary bracing; 205. Reserved hole. Detailed Implementation

[0042] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0043] In the description of this invention, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0044] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" 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.

[0045] Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0046] According to the first aspect of this application, see Figures 1 to 10 Firstly, an adjustable cofferdam structure is provided, including two pile foundations and a bracing 2 located between the two pile foundations.

[0047] The length of each pile 1 is adjustable; pile 1 is used to be inserted into the foundation 6 to fix the cofferdam, and can be pulled to a predetermined length according to the soil conditions. Figure 1 As shown, the bracing 2 is fixedly connected between two pile foundations 1. The length of the bracing is adjustable, and the bracing is fixedly connected to the pile foundations 1 by walers 4. A cofferdam filling zone 3 is formed between two adjacent pile foundations 1.

[0048] This application allows for adjustment of the spacing between two adjacent pile foundations 1 by adjusting the length of the bracing, thereby changing the width of the cofferdam structure. The length of the cofferdam inserted into the foundation 6 is set by adjusting the length of each pile foundation 1. One side of the cofferdam structure is water 5. The cofferdam provided by this application has strong anti-overturning capacity and stability, can adapt to various construction environments, is easy to operate, and is conducive to widespread use.

[0049] In one feasible approach, the pile foundation 1 is a multi-stage expansion joint structure.

[0050] Specifically, such as Figures 2 to 5 As shown, the pile foundation 1 includes a primary foundation 101, a secondary foundation 105, and a tertiary foundation 106. The primary foundation 101 and the secondary foundation 105 are both hollow cylinders with open bottoms. The secondary foundation 105 is coaxially fitted inside the primary foundation 101, and the tertiary foundation 106 is coaxially fitted inside the secondary foundation 105.

[0051] It should be noted that the diameters of the primary matrix 101, secondary matrix 105, and tertiary matrix 106 decrease sequentially. The diameter of the secondary matrix 105 is 60%-90% of the diameter of the primary matrix 101, and the diameter of the tertiary matrix 106 is 60%-90% of the diameter of the secondary matrix 105. The length of the secondary matrix 105 is 70%-90% of the length of the primary matrix 101, and the length of the tertiary matrix 106 is 70%-90% of the length of the secondary matrix 105.

[0052] In one feasible embodiment, the outer surfaces of the primary substrate 101, the secondary substrate 105, and the tertiary substrate 106 are all provided with external threads 102. The provision of external threads 102 makes it easier for the pile foundation 1 to be inserted into the foundation 6 when the soil is relatively hard.

[0053] It should be noted that the protrusion height of the external thread 102 is 1%-5% of the diameter of the pile foundation 1, and the spacing between two adjacent turns of external thread 102 is 10%-40% of the length of the pile foundation 1. The protrusion height and spacing of the external thread 102 on the primary base 101, the secondary base 105, and the tertiary base 106 can be set according to the actual engineering conditions.

[0054] In one feasible embodiment, the primary substrate 101 and the secondary substrate 105 are both hollow steel pipes with a predetermined wall thickness, and the tertiary substrate 106 can be a hollow steel pipe or a solid cylindrical steel pipe.

[0055] In one feasible approach, such as Figure 4 and Figure 5 As shown, four second elastic members 103 are provided on the top of the secondary substrate 105, and four third elastic members are provided on the top of the tertiary substrate 106, as follows. Figure 5 As shown, four first through holes 108 are provided at the bottom of the primary substrate 101, and four second through holes are provided at the bottom of the secondary substrate 105. The first through holes 108 are positioned corresponding to the second elastic members 103, and the first through holes 108 are used to limit the elastic members after the second elastic members 103 extend. The second through holes are positioned corresponding to the third elastic members, and the second through holes are used to limit the elastic members after the third elastic members extend.

[0056] When the second elastic element 103 or the third elastic element extends, the bonding friction between the pile foundation 1 and the soil is enhanced, making the cofferdam structure more stable. When the secondary foundation 105 is inserted into the primary foundation 101, the second elastic element 103 compresses the inner wall of the primary foundation 101. When the tertiary foundation 106 is inserted into the secondary foundation 105, the third elastic element compresses the inner wall of the secondary foundation 105, making the multi-stage pile foundation structure more stable.

[0057] It should be noted that the second elastic element 103 is fixedly connected to the secondary substrate 105 by welding, and the third elastic element is fixedly connected to the tertiary substrate 106 by welding. The four first through holes 108 are evenly distributed on the inner wall of the primary substrate 101, and the four second through holes are evenly distributed on the inner wall of the secondary substrate 105.

[0058] According to construction requirements, when the length of pile foundation 1 needs to be increased, the secondary foundation 105 is extracted from the primary foundation 101. The second elastic element 103 slides along the inner wall of the primary foundation 101. When the second elastic element 103 slides to the position of the first through hole 108, it slides out through the first through hole 108 to fix the relative position between the secondary foundation 105 and the primary foundation 101. According to construction requirements, when the length of the pile foundation structure needs to be increased again, the tertiary foundation 106 is extracted from the secondary foundation 105. At this time, the third elastic element slides along the inner wall of the secondary foundation 105. When the third elastic element slides to the position of the second through hole, it slides out through the second through hole to fix the relative position between the tertiary foundation 106 and the secondary foundation 105, so that the pile foundation structure still has strong stability after being lengthened.

[0059] In one feasible approach, such as Figure 5 and Figure 6 As shown, both the second elastic element 103 and the third elastic element, when unfolded, are conical. The unfolded length of either the second or third elastic element is 2-5 times the horizontal distance between two adjacent pile foundations 1. The minimum length of either the second or third elastic element under compression is 0.8-0.9 times the horizontal distance between two adjacent pile foundations 1. The maximum circular diameter of the conical shape projected onto the sidewall of the pile foundation 1 is 1.5-4 times the horizontal distance between adjacent pile foundations 1.

[0060] In one feasible approach, such as Figure 7 As shown, strip-shaped buffer layers 109 are attached to the inner walls of the primary substrate 101 and the secondary substrate 105. The strip-shaped buffer layers are used to prevent the inner walls from being scratched by the end of the cone.

[0061] It should be noted that the central axis of each strip-shaped buffer layer 109 corresponds to the conical center line of the corresponding second elastic element 103 or third elastic element, and the length of the strip-shaped buffer layer 109 is the length from the second elastic element 103 to the first through hole 108. The strip-shaped buffer layer 109 is made of a wear-resistant material and has the ability to be reused a predetermined number of times.

[0062] Specifically, the diameter of the first through hole 108 is the same as the maximum diameter of the second elastic element 103, and the diameter of the second through hole is the same as the maximum diameter of the third elastic element.

[0063] In one feasible approach, multiple pads are placed at the bottom of both the primary and secondary foundations. These pads act as a buffer during the pile foundation pull-out process.

[0064] Specifically, in this embodiment, as follows: Figure 6 As shown, four first pads 104 are provided at the bottom of the primary substrate 101, and the first pads 104 are fixedly connected to the primary substrate 101 by welding or other means. Four second pads are provided at the bottom of the secondary substrate 105. The second pads are fixedly connected to the secondary substrate 105 by welding or other means.

[0065] Specifically, the thickness of the pad is the same as the thickness of the compressed elastic element, and the length of the pad is 1.5-3 times the thickness of the pad. The pads are evenly distributed on the inner wall of the pile foundation 1, and the lower part of each pad is flush with the bottom edge of the pile foundation 1.

[0066] In one feasible approach, such as Figure 8 As shown, a tapered drill bit 107 is provided at the bottom of the three-stage substrate 106.

[0067] Specifically, the diameter of the tapered drill bit 107 is 1.5-2 times the diameter of the primary base 101. The height of the tapered drill bit 107 is 1.5-3 times its bottom diameter.

[0068] In one feasible approach, such as Figure 8 As shown, a threaded section 111 is provided at the bottom of the three-stage base 106, and the tapered drill bit 107 is detachably connected to the bottom of the three-stage base 106 through the threaded section 111, so that the tapered drill bit 107 can be easily replaced when it is damaged.

[0069] Specifically, the height of the threaded section 111 is 0.5-1.5 times the diameter of the third-level base 106.

[0070] It should be noted that a connecting edge 110 is provided around the periphery of the tapered drill bit 107. The connecting edge 110 extends upward, and its height is 20%-50% of the diameter of the tapered drill bit 107. The connecting edge 110 is made of magnetic material, and when the tertiary substrate 106 and the secondary substrate 105 are inserted into the pile foundation structure, the connecting edge 110 is connected to the outer wall of the primary substrate 101 by magnetic attraction.

[0071] It should also be noted that the pad can be made of a material that can generate a large magnetic attraction force on some metals. When the tertiary matrix 106 and the secondary matrix 105 are inserted into the pile foundation structure, the connecting edge 110 is connected to the pad by magnetic attraction force.

[0072] In one feasible approach, such as Figure 4 and Figure 7As shown, the second elastic element 103 compresses the inner wall of the primary matrix 101, and the third elastic element compresses the inner wall of the secondary matrix 105 when the tertiary matrix 106 is inserted into the secondary matrix 105, thereby making the pile foundation structure more stable.

[0073] In one feasible approach, such as Figure 9 and Figure 10 As shown, the support is a two-stage telescopic cylindrical structure, including a primary support 204 and a secondary support 201. The secondary support 201 is fitted inside the primary support 204 and can be pulled out to change the length of the support according to engineering requirements.

[0074] Specifically, such as Figure 9 and Figure 10 As shown, multiple bracing buckles 203 are provided at the insertion end of the secondary bracing 201, and multiple buttons 202 are provided at the extension end of the secondary bracing 201. The bracing buckles 203 and the buttons 202 are inserted into the secondary bracing 201 radially. The insertion ends of the bracing buckles 203 and the insertion ends of the buttons 202 are connected by a connecting plate. Figure 10 As shown, when the button 202 is pressed, the counter-support buckle 203 slides into the secondary counter-support 201 along with the button 202. At this time, the secondary counter-support 201 is pulled and its position is adjusted.

[0075] The distance between the insert end of the counter-bracing buckle 203 and the insert end of the counter-bracing buckle 203 is 5%-15% of the length of the secondary counter-bracing 201. The distance between the protruding end of the button 202 and the secondary counter-bracing 201 is 5%-15% of the length of the secondary counter-bracing 201. The counter-bracing buckle 203 and the button 202 are sized correspondingly, and the length of either the counter-bracing buckle 203 or the button 202 is 1-3 times its diameter.

[0076] like Figure 9 As shown, multiple pre-drilled holes 205 are arranged on the side wall of the primary support 204 along the sliding direction of the support buckle 203. The pre-drilled holes 205 are used for the support buckle 203 to extend and limit its position. After the support buckle 203 extends out of a certain pre-drilled hole 205, the relative position of the primary support 204 and the secondary support 201 is fixed.

[0077] It should be noted that the axis of the bracing is 0.5m-1.5m below the top elevation of pile foundation 1. The length of the primary bracing 204 is set according to actual engineering needs, and the length of the secondary bracing 201 is 70%-90% of the length of the primary bracing. The diameter of the reserved hole 205 is 5%-15% of the diameter of the primary bracing 204, and the interval between two adjacent reserved holes 205 is 5%-30% of the length of the primary bracing 204.

[0078] It should also be noted that the materials for the bracing, bracing clip 203, and button 202 will depend on the actual project conditions. The wall thickness of the primary bracing 204 and pile 1 will also depend on the actual project conditions. The specific parameters such as the wall thickness, material, length, and diameter of pile 1 and the bracing need to be determined through stability calculations. The soil properties of the backfill and the model parameters of the waler 4 will depend on the actual situation and must meet the stability calculation requirements.

[0079] According to a second aspect of this application, an adjustable cofferdam construction method is also provided, using the adjustable cofferdam structure provided in the first aspect, comprising the following steps:

[0080] S1. Drill holes and conduct geological surveys on the soil of the foundation 6 at the project site to obtain soil layer parameters, determine the topographic and geological parameters based on the soil layer parameters, and determine the length of the primary foundation 101 and the length of the primary support 204 based on the topographic and geological parameters.

[0081] S2. When the actual geological conditions are worse than the topographic and geological parameters, pull out the secondary foundation 105 or pull out the secondary foundation 105 and the tertiary foundation 106 at the same time to adjust the length of the pile foundation 1 until it meets the safety and stability requirements; drive the adjusted pile foundation 1 into the soil.

[0082] S4. After driving the pile foundation 1 to the design elevation, install the bracing 2 between two adjacent pile foundations 1.

[0083] S5. Backfill soil 3 in the cofferdam filling area between pile foundations 1;

[0084] S6. After the project is completed, dismantle and recycle pile 1 and bracing 2.

[0085] In one feasible approach, step S2 further includes at least the following: widening and clearing the soil, and installing grouting anchors on the cleared surface near the entrance of the sinkhole.

[0086] In one feasible approach, step S4 further includes at least the following: adjusting the length of the bracing 2 according to the distance between two adjacent pile foundations 1.

[0087] In summary, this application provides an adjustable cofferdam structure and a cofferdam construction method. The length and width of the cofferdam structure can be adjusted to adapt to various geological conditions, meet various engineering needs, and increase the versatility of the cofferdam.

[0088] When the second elastic element 103 or the third elastic element extends, the bonding friction between the pile foundation and the soil of the foundation 6 is enhanced, thereby enhancing the overturning resistance of the cofferdam and improving its stability.

[0089] By setting the external thread 102 on the pile foundation surface, the bonding friction with the soil can be enhanced, thereby enhancing the overturning resistance of the cofferdam and improving its stability.

[0090] By setting adjustable-length bracing, the stability and safety of the cofferdam can be enhanced, meeting the requirements of actual engineering projects.

[0091] By setting the diameter and length of each stage of the foundation in a multi-section pile foundation structure to decrease sequentially, compared with steel pipe pile cofferdams of equal length and diameter, it can adapt to various engineering needs, has universality, and saves more material weight and costs.

[0092] The conical drill bit 107 helps the pile foundation to penetrate into the hard strata more easily when constructing the cofferdam.

[0093] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. An adjustable cofferdam structure, characterized in that, It includes two pile foundations and a bracing system between the two pile foundations; The length of each pile foundation is adjustable; the pile foundation is used to be inserted into the foundation to fix the cofferdam structure, and can be adjusted to a predetermined length according to the soil conditions; the bracing is fixedly connected between two pile foundations, the length of the bracing is adjustable, and the bracing is fixedly connected to the pile foundation by walers; a cofferdam filling area is formed between two adjacent pile foundations; Both the pile foundation and the bracing are multi-stage expansion and contraction structures. The pile foundation includes a primary foundation, a secondary foundation, and a tertiary foundation; the primary foundation and the secondary foundation are both hollow cylinders with open bottoms, the secondary foundation is coaxially fitted inside the primary foundation, and the tertiary foundation is coaxially fitted inside the secondary foundation; The outer surfaces of the primary matrix, the secondary matrix, and the tertiary matrix are all provided with external threads; A second elastic element is provided on the top of the secondary substrate, and a third elastic element is provided on the top of the tertiary substrate; a first through hole is provided at the bottom of the primary substrate, and a second through hole is provided at the bottom of the secondary substrate; the first through hole is used to limit the second elastic element after it extends out, and the second through hole is used to limit the third elastic element after it extends out.

2. The adjustable cofferdam structure according to claim 1, characterized in that, A strip-shaped buffer layer is attached to the inner wall of the primary substrate and the secondary substrate, and the length of the strip-shaped buffer layer is the length from the second elastic element to the first through hole.

3. The adjustable cofferdam structure according to claim 1, characterized in that, Multiple pads are provided at the bottom of both the primary substrate and the secondary substrate.

4. The adjustable cofferdam structure according to claim 1, characterized in that, A tapered drill bit is provided at the bottom of the tertiary substrate, the diameter of which is 1.5-2 times the diameter of the primary substrate; the tapered drill bit is detachably connected to the bottom of the tertiary substrate via an external thread.

5. The adjustable cofferdam structure according to claim 1, characterized in that, The support is a two-stage telescopic cylindrical structure, including a primary support and a secondary support, with the secondary support nested inside the primary support; Multiple bracing buckles are provided at the insertion end of the secondary bracing, and multiple buttons are provided at the extension end of the secondary bracing. The bracing buckles and the buttons are inserted into the secondary bracing along the radial direction of the secondary bracing. The insertion ends of the bracing buckles and the insertion ends of the buttons are connected by a connecting plate. Multiple pre-drilled holes are arranged on the side wall of the first-level support along the sliding direction of the support buckle. The pre-drilled holes are used for the support buckle to extend and limit the support buckle.

6. An adjustable cofferdam construction method, characterized in that, Using the adjustable cofferdam structure according to any one of claims 1 to 5 specifically includes the following steps: S1. Drill holes and conduct geological surveys on the soil at the project site to obtain soil layer parameters, determine the topographic and geological parameters based on the soil layer parameters, and determine the length of the primary base and the length of the primary support based on the topographic and geological parameters. S2. When the actual geological conditions are worse than the topographic geological parameters, adjust the length of the pile foundation until the safety and stability requirements are met, and drive the adjusted pile foundation into the soil. S3. After driving the piles to the design elevation, install bracing between two adjacent piles. S4. Backfill soil in the cofferdam filling area between the pile foundations; S5. After the project is completed, the pile foundation and bracing will be dismantled and recycled.

Images