CN220847665U - Cofferdam structure with adjustable - Google Patents

Abstract

The application provides an adjustable cofferdam structure. The cofferdam structure comprises 2 pile foundations and a pair support arranged between the 2 pile foundations. The length of each pile foundation is adjustable; the pile foundation is used for being inserted into the foundation, fixing the cofferdam structure and adjusting the cofferdam structure to a preset length according to soil drawing; the pair support is fixedly connected between 2 pile foundations, the length of the pair support is adjustable, and the pair support is fixedly connected with the pile foundations through an enclosing purlin; and forming a cofferdam soil filling area between two adjacent pile foundations. The application provides an adjustable cofferdam structure, the length and the width of which can be adjusted to adapt to various geological conditions, meet various engineering requirements and increase the universality of the cofferdam.

Description

Cofferdam structure with adjustable

Technical Field

The application relates to the technical field of water conservancy and hydropower construction, in particular to an adjustable cofferdam structure.

Background

Common cofferdam structures in hydraulic and hydroelectric engineering comprise earth-rock cofferdams, steel sheet piles or steel pipe piles, and the like. In many small-sized projects, the earth-rock cofferdam has relatively simple process and low cost, but in practical projects, due to the restrictions and considerations on the project scope, navigation requirements, protection of adjacent buildings and the like, only cofferdams such as steel pipe piles and the like with relatively high cost and better safety and stability can be selected. Moreover, in some projects with complicated and changeable geology, geological and topographic parameters obtained by early design investigation can come in and go out from actual conditions, so that the cofferdam meeting the design requirements cannot be adapted to the actual environment of the project site and completely meet the requirements of safety and stability.

Therefore, the cofferdam which meets the requirements of environmental protection civilized construction, meets the actual requirements of general engineering, has lower relative cost, has a feasible technology, simple structure and strong universality becomes a research-worthy hotspot.

Disclosure of utility model

The embodiment of the application aims to provide an adjustable cofferdam structure which can adjust the length and width of a cofferdam according to requirements so as to meet various engineering requirements.

The application particularly provides an adjustable cofferdam structure which comprises 2 pile foundations and a pair of supports arranged between the 2 pile foundations.

The length of each pile foundation is adjustable; the pile foundation is used for being inserted into the foundation, fixing the cofferdam structure and adjusting the cofferdam structure to a preset length according to soil drawing; the pair support is fixedly connected between 2 pile foundations, the length of the pair support is adjustable, and the pair support is fixedly connected with the pile foundations through an enclosing purlin; and forming a cofferdam soil filling area between two adjacent pile foundations.

In one embodiment, the pile foundation and the pair of struts are of a multi-stage telescopic structure.

In one embodiment, the pile foundation comprises a primary matrix, a secondary matrix and a tertiary matrix; the primary base body and the secondary base body are hollow cylinders with openings at bottoms, the secondary base bodies are coaxially sleeved in the primary base body, and the tertiary base bodies are coaxially sleeved in the secondary base body.

In one embodiment, the outer surfaces of the primary base body, the secondary base body and the tertiary base body are all provided with external threads.

In one embodiment, a second elastic member is disposed on top of the secondary matrix, and a third elastic member is disposed on top of the tertiary matrix; a first through hole is formed in the bottom of the primary matrix, and a second through hole is formed in the bottom of the secondary matrix; the first through hole is used for limiting the second elastic piece after the second elastic piece stretches out, and the second through hole is used for limiting the third elastic piece after the third elastic piece stretches out.

In one embodiment, a strip-shaped buffer layer is attached to the inner walls of the primary matrix and the secondary matrix, and the length of the strip-shaped buffer layer is the length from the second elastic piece to the first through hole.

In one embodiment, a plurality of pads are disposed at the bottom of each of the primary and secondary substrates.

In one implementation mode, a conical drill bit is arranged at the bottom of the three-stage base body, and the diameter of the conical drill bit is 1.5-2 times that of the primary base body; the cone drill bit is detachably connected with the bottom of the three-stage matrix through external threads.

In one implementation mode, the pair support is of a two-stage telescopic cylinder structure and comprises a first-stage pair support and a second-stage pair support, and the second-stage pair support is sleeved in the first-stage pair support;

The inserting end of the second-stage opposite support is provided with a plurality of opposite support buckles, the extending end of the second-stage opposite support is provided with a plurality of buttons, the opposite support buckles and the buttons are inserted into the second-stage opposite support along the radial direction of the second-stage opposite support, and the inserting end of the opposite support buckles and the inserting end of the buttons are connected through a connecting plate;

The side wall of the first-stage opposite bracing is provided with a plurality of preformed holes along the sliding direction of the opposite bracing buckle, and the preformed holes are used for extending out the opposite bracing buckle and limiting the opposite bracing buckle.

Compared with the prior art, the application has the beneficial effects that:

In the technical scheme of the application, when the second elastic piece or the third elastic piece extends out, the bonding friction force between the pile foundation and the soil body is enhanced, so that the anti-overturning capacity of the cofferdam is enhanced, and the stability of the cofferdam is improved.

Through the setting of pile foundation surface external screw thread, can strengthen the bonding friction with the soil body to strengthen the anti-capsizing ability of cofferdam, improve the stability of cofferdam.

The length-adjustable opposite support is arranged, so that the stability and safety of the cofferdam can be enhanced, and the requirements of actual engineering are met.

Through progressively decreasing the setting in proper order each level base member diameter and length in the multisection pile foundation structure, compare with the steel-pipe pile cofferdam of equal length, equal diameter, can adapt to multiple engineering actual demand, possess universality, save material weight more and practice thrift the cost.

Through the setting of cone drill bit, can help the pile foundation more light stretch into in the hard stratum when setting up the cofferdam.

The application provides an adjustable cofferdam structure, the length and the width of which can be adjusted to adapt to various geological conditions, meet various engineering requirements and increase the universality of the cofferdam.

Drawings

FIG. 1 is a schematic structural view of an adjustable weir structure according to an embodiment of the present utility model.

FIG. 2 is an elevation view of pile foundation in a collapsed condition in an adjustable weir structure according to an embodiment of the present utility model.

FIG. 3 is an elevation view of pile foundation in an expanded state in an adjustable weir structure according to an embodiment of the present utility model.

FIG. 4 is a top view of a pile foundation in a collapsed condition in an adjustable weir structure according to an embodiment of the present utility model.

FIG. 5 is a top view of a pile foundation for deploying only a secondary matrix in an adjustable cofferdam structure in accordance with an embodiment of the present utility model.

Fig. 6 is a schematic view showing the structure of the second elastic member in the unfolded state in the adjustable cofferdam structure according to the embodiment of the present utility model.

Fig. 7 is a schematic view of the structure of the second elastic member in a compressed state in the adjustable weir structure according to the embodiment of the present utility model.

FIG. 8 is a schematic illustration of the connection of a cone drill bit to a tertiary matrix in an adjustable weir structure in accordance with an embodiment of the present utility model.

FIG. 9 is a front view of a pair of braces in a collapsed condition in an adjustable weir structure according to an embodiment of the present utility model.

FIG. 10 is a schematic view of the structure of the adjustable cofferdam structure of the embodiment of the present utility model, wherein the secondary counter-support is in different states in the primary counter-support.

Wherein reference numerals are as follows:

1. Pile foundation; 2. the support is opposite; 3. filling soil; 4. enclosing purlin; 5. a body of water; 6. a foundation; 101. a first-order substrate; 102. an external thread; 103. a second elastic member; 104. a cushion block; 105. a secondary matrix; 106. a third-stage substrate; 107. a cone drill bit; 108. a first through hole; 109. a strip-shaped buffer layer; 110. a connecting edge; 111. a threaded section; 201. two-stage opposite bracing; 202. a button; 203. the opposite support buckle; 204. first-stage opposite bracing; 205. and (5) reserving holes.

Detailed Description

The following describes the embodiments of the present utility model in further detail with reference to the accompanying drawings. These embodiments are merely illustrative of the present utility model and are not intended to be limiting.

In the description of the present utility model, it should be noted that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the present utility model and simplifying the description, and do not indicate or imply that the apparatus or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present utility model. Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present utility model, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present utility model can be understood by those of ordinary skill in the art according to the specific circumstances.

Furthermore, in the description of the present utility model, unless otherwise indicated, the meaning of "a plurality" is two or more.

Referring to fig. 1 to 10, the application provides an adjustable cofferdam structure, which comprises 2 pile foundations and a pair of struts 2 arranged between the 2 pile foundations.

The length of each pile foundation 1 is adjustable; pile foundation 1 is used for inserting in foundation 6, fixes the cofferdam to predetermined length according to the soil texture pull. As shown in fig. 1, the opposite struts 2 are fixedly connected between 2 pile foundations 1, the lengths of the opposite struts are adjustable, and the opposite struts are fixedly connected with the pile foundations 1 through enclosing purlins 4. A cofferdam filling area 3 is formed between two adjacent pile foundations 1.

The distance between two adjacent pile foundations 1 can be adjusted by adjusting the length of the opposite support, so that the width of the cofferdam structure can be changed. 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 a water body 5, and the cofferdam provided by the application has stronger anti-capsizing capability and stability, can adapt to various construction environments, is simple and convenient to operate, and is beneficial to popularization and use.

In one embodiment, the pile foundation 1 is a multi-stage telescopic structure.

Specifically, as shown in fig. 2 to 5, the pile foundation 1 includes a primary matrix 101, a secondary matrix 105, and a tertiary matrix 106. The primary base body 101 and the secondary base body 105 are hollow cylinders with openings at bottoms, the secondary base body 105 is coaxially sleeved in the primary base body 101, and the tertiary base body 106 is coaxially sleeved in the secondary base body 105.

The diameters of the primary matrix 101, the secondary matrix 105, and the tertiary matrix 106 decrease in order. 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.

In one embodiment, the external threads 102 are provided on the outer surfaces of the primary matrix 101, the secondary matrix 105 and the tertiary matrix 106, and the pile foundation 1 is easier to be inserted into the foundation 6 under the condition of harder soil property by the arrangement of the external threads 102.

It should be noted that, the height of the protrusion of the external thread 102 is 1% -5% of the diameter of the pile foundation 1, the distance between two adjacent circles of external threads 102 is 10% -40% of the length of the pile foundation 1, and the heights of the protrusions of the external threads 102 and the distances between the external threads 102 on the primary base 101, the secondary base 105 and the tertiary base 106 can be set according to actual engineering conditions.

In one embodiment, the primary matrix 101 and the secondary matrix 105 are hollow steel pipes with a predetermined wall thickness, and the tertiary matrix 106 may be hollow steel pipes or solid cylindrical steel pipes.

In one embodiment, as shown in fig. 4 and fig. 5, 4 second elastic members 103 are disposed on the top of the secondary matrix 105, 4 third elastic members are disposed on the top of the tertiary matrix 106, as shown in fig. 5, 4 first through holes 108 are disposed on the bottom of the primary matrix 101, and 4 second through holes are disposed on the bottom of the secondary matrix 105. The first through hole 108 corresponds to the position of the second elastic piece 103, the first through hole 108 is used for limiting the elastic piece after the second elastic piece 103 stretches out, the second through hole corresponds to the position of the third elastic piece, and the second through hole is used for limiting the elastic piece after the third elastic piece stretches out.

When the second elastic piece 103 or the third elastic piece stretches out, the bonding friction force between the pile foundation 1 and the soil body is enhanced, and the cofferdam structure is firmer. When the second base 105 is inserted into the first base 101, the second elastic member 103 presses the inner wall of the first base 101, and the third base 106 is inserted into the second base 105, and presses the inner wall of the second base 105 through the third elastic member, so that the multi-stage pile foundation structure is more stable.

The second elastic member 103 is fixedly connected to the second-stage base 105 by welding, and the third elastic member is fixedly connected to the third-stage base 106 by welding. The 4 first through holes 108 are uniformly distributed on the inner wall of the primary matrix 101, and the 4 second through holes are uniformly distributed on the inner wall of the secondary matrix 105.

According to construction requirements, when the length of the pile foundation 1 needs to be increased, the secondary base body 105 is pulled out of the primary base body 101, the second elastic piece 103 slides along the inner wall of the primary base body 101, and when the second elastic piece 103 slides to the position of the first through hole 108, the second elastic piece slides out through the first through hole 108 to fix the relative position between the secondary base body 105 and the primary base body 101. According to the construction requirement, when the length of the pile foundation structure needs to be increased again, the third-stage base body 106 is pulled out of the second-stage base body 105, at the moment, the third elastic piece slides along the inner wall of the second-stage base body 105, and slides out through the second through hole when the third elastic piece slides to the position of the second through hole, so that the relative position between the third-stage base body 106 and the second-stage base body 105 is fixed, and the pile foundation structure still has stronger stability after being lengthened.

In one embodiment, as shown in fig. 5 and 6, the second elastic member 103 and the third elastic member are both conical after being unfolded, and the length of the second elastic member 103 or the third elastic member after being unfolded is 2-5 times of the horizontal interval distance between two adjacent pile foundations 1. The minimum length of the second elastic member 103 or the third elastic member in the extruded state is 0.8-0.9 times of the horizontal spacing distance between two adjacent pile foundations 1. The maximum circular diameter of the cone projected on the side wall of the pile foundation 1 is 1.5-4 times of the horizontal interval distance of the adjacent pile foundations 1.

In one embodiment, as shown in fig. 7, a strip buffer layer 109 is attached to the inner walls of the primary base 101 and the secondary base 105, and the strip buffer layer is used to prevent the inner walls from being scratched by the tip of the cone.

It should be noted that, the central axis of each strip-shaped buffer layer 109 is disposed corresponding to the cone central axis of the corresponding second elastic member 103 or third elastic member, and the length of the strip-shaped buffer layer 109 is the length from the second elastic member 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.

Specifically, the diameter of the first through hole 108 is consistent with the maximum diameter of the second elastic member 103, and the diameter of the second through hole is consistent with the maximum diameter of the third elastic member.

In one embodiment, a plurality of pads are disposed at the bottom of each of the primary and secondary substrates. The cushion block plays a role in buffering in the pile foundation pulling process.

Specifically, in this embodiment, as shown in fig. 6, 4 first cushion blocks 104 are disposed at the bottom of the primary base 101, and the first cushion blocks 104 are fixedly connected with the primary base 101 by welding or other manners. At the bottom of the secondary matrix 105, 4 second pads are provided. The second pad is fixedly connected to the secondary matrix 105 by welding or the like.

Specifically, the thickness of the cushion block is consistent with the thickness of the elastic piece after compression, and the length of the cushion block is 1.5-3 times of the thickness of the cushion block. The cushion blocks are uniformly distributed on the inner wall of the pile foundation 1, and the lower part of each cushion block is flush with the bottom edge of the pile foundation 1.

In one embodiment, as shown in FIG. 8, a cone bit 107 is provided at the bottom of the tertiary matrix 106.

Specifically, the diameter of the cone drill bit 107 is 1.5-2 times the diameter of the primary matrix 101. The height of the cone drill bit 107 is 1.5-3 times its bottom surface diameter.

In one embodiment, as shown in fig. 8, a threaded section 111 is provided at the bottom of the tertiary base 106, and the cone drill bit 107 is detachably connected to the bottom of the tertiary base 106 through the threaded section 111, so that the cone drill bit 107 can be easily replaced when damaged.

Specifically, the height of the thread segments 111 is 0.5-1.5 times the diameter of the tertiary matrix 106.

A ring of connecting edges 110 is provided on the circumference of the cone drill bit 107, the connecting edges 110 protrude upward, and the height of the connecting edges 110 is 20% -50% of the diameter of the cone drill bit 107. The connecting edge 110 is made of magnetic materials, and when the three-level matrix 106 and the second-level matrix 105 are inserted into the pile foundation structure, the connecting edge 110 is connected with the outer wall of the first-level matrix 101 through magnetic attraction.

It should be further noted that, the spacer may be made of a material capable of generating a large magnetic attraction force to a part of metal, and the connection edge 110 is connected with the spacer by the magnetic attraction force when the tertiary matrix 106 and the secondary matrix 105 are inserted into the pile foundation structure.

In one embodiment, as shown in fig. 4 and 7, the second elastic member 103 presses the inner wall of the primary base 101, and the third elastic member presses the inner wall of the secondary base 105 when the tertiary base 106 is inserted into the secondary base 105, so that the pile foundation structure is more stable.

In an embodiment, as shown in fig. 9 and fig. 10, the pair support is of a two-stage telescopic cylinder structure, and includes a first-stage pair support 204 and a second-stage pair support 201, where the second-stage pair support 201 is sleeved in the first-stage pair support 204, and is pulled according to engineering requirements to change the length of the pair support.

Specifically, as shown in fig. 9 and 10, a plurality of opposite support buckles 203 are provided at the insertion end of the secondary opposite support 201, a plurality of buttons 202 are provided at the extension end of the secondary opposite support 201, the opposite support buckles 203 and the buttons 202 are inserted into the secondary opposite support 201 along the radial direction of the secondary opposite support 201, and the insertion ends of the opposite support buckles 203 and the buttons 202 are connected by a connecting plate. As shown in fig. 10, when the button 202 is pressed, the pair of support buckles 203 slide into the secondary pair of supports 201 together with the button 202, and at this time, the secondary pair of supports 201 is pulled and the position of the secondary pair of supports 201 is adjusted.

The distance between the pair of bracing buckles 203 and the insertion end of the pair of bracing buckles 203 is 5% -15% of the length of the secondary pair of bracing 201. The distance between the button 202 and the protruding end of the secondary pair of struts 201 is 5% -15% of the length of the secondary pair of struts 201. The opposite-bracing buckle 203 corresponds to the size of the button 202, and the length of the opposite-bracing buckle 203 or the button 202 is 1-3 times of the diameter thereof.

As shown in fig. 9, a plurality of preformed holes 205 are arranged on the side wall of the primary bracing 204 along the sliding direction of the bracing buckle 203, and the preformed holes 205 are used for extending out the bracing buckle 203 and limiting the bracing buckle 203. After the opposite bracing buckle 203 extends out of a certain reserved hole 205, the relative positions of the primary opposite bracing 204 and the secondary opposite bracing 201 are fixed.

The axis of the opposite bracing is 0.5m-1.5m lower than the top elevation of the pile foundation 1. The length of the first-stage opposite support 204 is set according to actual engineering requirements, and the length of the second-stage opposite support 201 is 70% -90% of the first-stage opposite support length. The diameter of the reserved holes 205 is 5% -15% of the diameter of the primary counter support 204, and the distance between two adjacent reserved holes 205 is 5% -30% of the length of the primary counter support 204.

It should be noted that the materials of the pair stay, the pair stay buckle 203 and the button 202 depend on the actual engineering situation. The wall thickness of the primary counter-bracing 204 primary and pile foundation 1 depends on the actual engineering situation. Specific parameters such as wall thickness, materials, length, diameter and the like of the pile foundation 1 and the opposite support are required to be determined through stable calculation. The soil body index of the filling and the model parameter of the enclosing purlin 4 are required to be determined according to actual conditions, and the stability calculation requirement is required to be met.

When in use, the application comprises the following steps:

s1, drilling and geological investigation are carried out on a soil body of a foundation 6 where an engineering is located to obtain soil layer parameters, the topography and geology parameters are determined according to the soil layer parameters, and the length of a primary matrix 101 and the length of a primary opposite support 204 are determined based on the topography and geology parameters;

S2, when the actual geological condition is worse than the topographic and geological parameters, the secondary matrix 105 is pulled or the secondary matrix 105 and the tertiary matrix 106 are pulled simultaneously, and the length of the pile foundation 1 is adjusted until the safety and stability requirements are met; driving the regulated pile foundation 1 into soil;

S4, after pile foundations 1 are driven to a designed elevation, installing a pair support 2 between two adjacent pile foundations 1;

s5, backfilling filling 3 in a cofferdam filling area between pile foundations 1;

S6, after the engineering is finished, removing the recovered pile foundation 1 and the opposite support 2.

In step S2, at least the following are included: and (3) expanding and digging a base, and arranging a grouting anchor rod on the base surface near the opening of the water falling hole.

In step S4, at least the following are included: the length of the opposite struts 2 is adjusted according to the distance between two adjacent pile foundations 1.

In summary, the application provides an adjustable cofferdam structure, the length and the width of which can be adjusted to adapt to various geological conditions, meet various engineering requirements and increase the universality of the cofferdam.

When the second elastic piece 103 or the third elastic piece stretches out, the bonding friction force between the pile foundation and the soil body of the foundation 6 is enhanced, so that the anti-overturning capacity of the cofferdam is enhanced, and the stability of the cofferdam is improved.

Through the setting of pile foundation surface external screw thread 102, can strengthen the bonding friction with the soil body to strengthen the anti-capsizing ability of cofferdam, improve the stability of cofferdam.

The length-adjustable opposite support is arranged, so that the stability and safety of the cofferdam can be enhanced, and the requirements of actual engineering are met.

Through progressively decreasing the setting in proper order each level base member diameter and length in the multisection pile foundation structure, compare with the steel-pipe pile cofferdam of equal length, equal diameter, can adapt to multiple engineering actual demand, possess universality, save material weight more and practice thrift the cost.

By the arrangement of the cone drill bit 107, pile foundations can be easily extended into hard formations when a cofferdam is constructed.

The foregoing is merely a preferred embodiment of the present utility model, and it should be noted that modifications and substitutions can be made by those skilled in the art without departing from the technical principles of the present utility model, and these modifications and substitutions should also be considered as being within the scope of the present utility model.

Claims (9)

1. An adjustable cofferdam structure is characterized by comprising 2 pile foundations and a pair of supports arranged between the 2 pile foundations;

The length of each pile foundation is adjustable; the pile foundation is used for being inserted into the foundation, fixing the cofferdam structure and adjusting the cofferdam structure to a preset length according to soil drawing; the pair support is fixedly connected between 2 pile foundations, the length of the pair support is adjustable, and the pair support is fixedly connected with the pile foundations through an enclosing purlin; and forming a cofferdam soil filling area between two adjacent pile foundations.

2. The adjustable weir structure of claim 1, wherein the pile foundation and the pair of struts are each of a multi-stage telescoping structure.

3. The adjustable weir structure of claim 2, wherein the pile foundation comprises a primary matrix, a secondary matrix, a tertiary matrix; the primary base body and the secondary base body are hollow cylinders with openings at bottoms, the secondary base bodies are coaxially sleeved in the primary base body, and the tertiary base bodies are coaxially sleeved in the secondary base body.

4. An adjustable weir structure according to claim 3 wherein the outer surfaces of the primary base, the secondary base and the tertiary base are each provided with external threads.

5. The adjustable weir structure of claim 4 wherein a second elastic member is disposed on top of the secondary matrix and a third elastic member is disposed on top of the tertiary matrix; a first through hole is formed in the bottom of the primary matrix, and a second through hole is formed in the bottom of the secondary matrix; the first through hole is used for limiting the second elastic piece after the second elastic piece stretches out, and the second through hole is used for limiting the third elastic piece after the third elastic piece stretches out.

6. The adjustable weir structure according to claim 5, wherein strip-shaped buffer layers are attached to the inner walls of the primary and secondary matrixes, and the length of each strip-shaped buffer layer is the length from the second elastic member to the first through hole.

7. An adjustable weir structure according to claim 3 wherein a plurality of pads are provided at the bottom of each of the primary and secondary matrices.

8. An adjustable weir structure according to claim 3 wherein a cone bit is provided at the bottom of the tertiary matrix, the cone bit having a diameter 1.5-2 times the diameter of the primary matrix; the cone drill bit is detachably connected with the bottom of the three-stage matrix through external threads.

9. The adjustable cofferdam structure of claim 2, wherein the pair of struts is a two-stage telescopic cylinder structure, comprising a first-stage pair of struts and a second-stage pair of struts, and the second-stage pair of struts is sleeved in the first-stage pair of struts;

The inserting end of the second-stage opposite support is provided with a plurality of opposite support buckles, the extending end of the second-stage opposite support is provided with a plurality of buttons, the opposite support buckles and the buttons are inserted into the second-stage opposite support along the radial direction of the second-stage opposite support, and the inserting end of the opposite support buckles and the inserting end of the buttons are connected through a connecting plate;

The side wall of the first-stage opposite bracing is provided with a plurality of preformed holes along the sliding direction of the opposite bracing buckle, and the preformed holes are used for extending out the opposite bracing buckle and limiting the opposite bracing buckle.