Cofferdam structure based on magnetic slurry and construction method thereof

Abstract

The invention provides a cofferdam structure based on magnetic slurry and a construction method thereof.The cofferdam structure comprises an inner surrounding structure and an outer surrounding structure which are different in shape, the inner surrounding structure comprises anchor rods and is driven into the water bottom through an anchor driving machine, and the anchor rods below the ground are connected with supporting rods above the ground through connectors; rb-Fe-B magnetic bars are sleeved with the supporting rods, plastic material layers wrap the supporting rods, and the plastic material layers are wrapped with the magnetic slurry adsorption outer layers. Or the rubidium-iron-boron magnetic rod is wrapped with a plastic material layer and is directly connected with the anchor head driven into the ground through the connector, and the magnetic slurry is adsorbed on the plastic material layer; after the magnetic slurry is adsorbed and solidified, a closed space is defined, then pile casting is conducted, after pile casting is completed, the connector is rotated and unlocked, the closed space is detached, and a cofferdam is formed by the magnetic slurry; the outer surrounding structure and the inner surrounding structure are closed protective structures manufactured in the same mode.

Description

Technical Field

[0001] The invention belongs to the field of civil engineering, and in particular relates to a cofferdam based on magnetic slurry and a construction method thereof. Background Art

[0002] With the continuous development of my country's infrastructure construction and the needs of globalization and economic development, my country's activities in coastal and marine areas have increased, and large-scale infrastructure construction in complex and extreme underwater environments has gradually been taken seriously. Underwater piling is a key underwater engineering technology used to drive pile foundations into underwater environments. This technology is particularly important in engineering projects in waters such as oceans and rivers, such as the construction of bridges, docks, offshore platforms and wind farms. Although the use of general cofferdams can temporarily solve the problem, how to better overcome the influence of water depth, water flow, geology and corrosion of the water environment has become a problem that troubles the staff.

[0003] The scouring of moving and flowing water causes the poured concrete slurry to be washed away, making it impossible for the steel bars to combine with the concrete mortar. Summary of the invention

[0004] The purpose of the present invention is to overcome the above-mentioned shortcomings and provide a cofferdam structure based on magnetic slurry and a construction method thereof. In the present invention, after the slurry is adsorbed, a closed space is formed to isolate the seawater outside, and the dynamic water becomes static water and then a steel cage is placed. When pouring piles, the steel bars and concrete mortar can be tightly combined. After the pouring piles are completed, the cofferdam can be disassembled by rotating the unlocking connector.

[0005] In order to achieve the above-mentioned technical features, the purpose of the present invention is achieved as follows: a cofferdam structure based on magnetic slurry, including an inner enclosure structure and an outer enclosure structure of different shapes, the inner enclosure structure including an anchor rod, and driven into the bottom of the water by an anchor driver, the anchor rod below the ground is connected to the support rod above the ground by a connector, the support rod is covered with a nylon iron boron magnetic rod inside, and the outer layer is wrapped with a plastic material layer, and the magnetic slurry is adsorbed on the outer layer wrapped on the plastic material layer; or the nylon iron boron magnetic rod is wrapped with a layer of plastic material outside, which is directly connected to the anchor head driven into the ground through a connector, and the magnetic slurry is adsorbed on the plastic material layer; the magnetic slurry is adsorbed and solidified to form a closed space, and then pile pouring is carried out. After the pile pouring is completed, the connector is rotated to unlock the closed space, and the cofferdam formed by the magnetic slurry is disassembled; the outer enclosure structure is a closed protective structure made in the same way as the inner enclosure structure.

[0006] The anchor rod below the connector, that is, the part below the ground, is called the anchor rod, and the part above the connector, that is, the part above the ground, is the supporting rod.

[0007] The anchor rod uses GPS to determine its position, and uses an anchor driver to drive the head of the anchor rod into the bottom of the water and part of the anchor rod is also inserted into the ground, or the anchor head is driven into the bottom of the water and connected to the NdFeB magnetic rod with a connector to form a circular, H-shaped or X-shaped figure.

[0008] The support rod is fixed by placing a hinge-type rotatable steel plate, and the steel plate is welded with a hollow cylindrical hole. The support rod is inserted into the hole and reinforced by pouring magnetic slurry, and a certain length is reserved to connect with the next steel plate through the solidified magnetic slurry.

[0009] If the water in which the steel plate is located is salt water, it is necessary to consider the corrosion effect of chloride ions on the steel bars. By placing a permanent magnet on one side of the steel plate and pouring magnetic slurry on the other side, the magnetic slurry is attracted to fill the inner wall of the steel plate and isolate the water and air from the outside.

[0010] The plastic material layer is made of PVC. Depending on the geological conditions, if the geology is hard, the support rod is not driven in, and the PVC is directly put on the outside of the NdFeB magnetic rod; if the geology is soft, a support rod is used, the outer layer is wrapped with PVC, and the NdFeB magnetic rod is put inside the anchor rod.

[0011] In soft geology, the NdFeB magnetic rod is sleeved inside the support rod to absorb the magnetic slurry through its strong magnetism; if the geology is hard, the NdFeB magnetic rod is directly connected to the anchor head driven into the ground with a connector.

[0012] The additive in the magnetic slurry is a 70% water glass solution, which is composed of water, cement, 70% water glass solution and ferromagnetic mineral powder, and the corresponding weight ratio is set to 1:2~2.2:1:0.4~0.5; The magnetic slurry is poured through a pouring pipe onto the support rod or the periphery of the NdFeB magnetic rod for adsorption, and after the magnetic slurry solidifies, a closed space is finally formed; The enclosed space selectively arranges support rods on the water flow impact surface according to the water flow direction and flow velocity to form an arc or rectangle, forming the first line of protection outside the enclosed space.

[0013] When the enclosed space is at a deep water level, the length of the support rod or the NdFeB magnetic rod is limited. A closed space of a certain height is formed first, and the NdFeB magnetic rod is taken out at the same time for continued use in the enclosed space of the next height. At this time, the water below this height is still water, and the concrete slurry is poured in sections by the conduit method. First, the concrete mortar within this height is poured, and then the enclosed space is formed upwards, and then poured, and so on, so as to achieve construction while building the cofferdam; The connector can be rotated to unlock and disassemble. It is a metal product with a PVC material on the outer layer. It is used to connect the anchor rod and the support rod as well as the NdFeB magnetic rod and the anchor head. After the pile pouring is completed, the cofferdam above the ground is rotated to disassemble.

[0014] A construction method of a cofferdam structure based on magnetic slurry comprises the following steps: First method: Step 1: Material preparation, making inner and outer structures, including anchor rods, plastic material layers, magnetic slurry, NdFeB magnetic rods, connectors, and support rods; Step 2: Preliminary preparation: In soft geology, a NdFeB magnetic rod is placed inside the support rod, and a layer of plastic material is wrapped outside. In hard geology, no support rod is used, and a layer of plastic material is directly wrapped outside the NdFeB magnetic rod. The plastic material layer is PVC. Step 3: Solution 1: Drive the anchor rod, install the connector, and use GPS technology to determine the location. In soft geology, use an anchor driver to drive the anchor rod into the water bottom, and use a connector to connect the anchor rod and the support rod. The spacing between the support rods is small, and more support rods are driven, eventually forming a circular, H-shaped or X-shaped pattern; Solution 2: Drive the anchor head and install the connector. In hard geology, directly use the NdFeB magnetic rod to connect with the anchor head driven into the ground through the connector, and finally form a circular, H-shaped or X-shaped figure; Step 4: Prepare magnetic slurry, mix cement, water glass and ferromagnetic mineral powder according to the required proportion to make a flowing slurry with magnetic properties and controllable curing time; Step 5: pour the magnetic slurry through the pouring pipe to the support rod or the surrounding of the NdFeB magnetic rod for adsorption, and form a closed space after the magnetic slurry solidifies; Step 6: Strengthen protection. The enclosed space can selectively arrange support rods on the water flow impact surface according to the water flow direction and flow rate to form an arc or rectangle, forming the first line of protection outside the enclosed space; Step 7: Dismantle the enclosed space. After the pile pouring is completed, rotate and unlock the connector of the support rod or NdFeB magnetic rod above the ground, and retrieve the materials above the ground for reuse; Second method: Step 1: Material preparation, making inner structure, including anchor rods, plastic material layer, magnetic slurry, connectors, support rods, and steel plates; Step 2: Preliminary preparation: wrap a layer of plastic material on the outside of the support rod; Step 3: Prepare magnetic slurry, mix cement, water glass and ferromagnetic mineral powder according to the required proportion to make a flowing slurry with magnetic properties and controllable curing time; Step 4: Drive the anchor rod, place the steel plate, install the connector, use GPS technology to determine the position, use the anchor driver to drive the anchor rod into the water bottom, connect the anchor rod and the support rod with the connector, adjust the angle of the steel plate, and insert the support rod into the hollow cylindrical hole of the steel plate. The steel plate reserves a certain length to connect with the next steel plate through magnetic slurry, expand the spacing between the support rods, and thus reduce the amount of support rods driven in; Step 5: Anti-corrosion measures. If the water quality of the steel plate is salt water, the corrosion effect of chloride ions on the steel bars needs to be considered. A permanent magnet is placed on one side of the steel plate, and magnetic slurry is poured on the other side to attract the magnetic slurry to fill the inner wall of the steel plate and isolate water and air from the outside. Step 6: Dismantle the enclosed space. After the pile pouring is completed, rotate and unlock the connector connecting the anchor rod and the support rod, retrieve the support rod on the ground and pull out the steel plate for reuse.

[0015] The present invention has the following beneficial effects: 1. The scouring of moving water and flowing water causes the concrete slurry to be washed away, making it impossible for the steel bars to combine with the concrete mortar. The self-aggregation ability of the magnetic slurry is utilized to adsorb around the anchor rod or the NdFeB magnetic rod to form a closed space, turning the moving water into still water, isolating the seawater outside, and then placing the steel cage so that the steel bars and the concrete mortar can be tightly combined, and finally the underwater pile is completed. Compared with traditional underwater piles, the present invention solves the problems of steel bar corrosion and the inability to effectively pour concrete slurry.

[0016] 2. By adopting the method of the present invention, the NdFeB magnetic rods, support rods, and steel plates above the ground can be dismantled and reused, saving costs. After the pile pouring is completed, the cofferdam above the ground can be removed by rotating the unlocking connector. And by covering the anchor rod or the outer layer of the NdFeB magnetic rod with PVC material, the magnetic slurry is adsorbed on the outer layer of PVC and solidified, and the NdFeB magnetic rod or anchor rod can be pulled out of the PVC for next use, saving the use cost.

[0017] 3. By adopting the method of the present invention, a greater impact force can be borne and the pile body can be protected from impact. Anchor rods or NdFeB magnetic rods are driven into the anchor head to combine with the anchor head, and the magnetic slurry is adsorbed and solidified to finally form a closed space, and anchor rods are arranged on the water flow impact surface to form an arc or rectangle, forming the first line of protection outside the closed space.

[0018] 4. Compared with the traditional cofferdam construction, the present invention is more convenient and quicker, and is easy to use. It only requires a series of simple operations such as driving anchor rods, anchor heads, and pouring slurry. It can be constructed while closing, and after a certain height of closed enclosure is formed in a short time, pile pouring can be carried out. The material is not heavy, easy to carry, and labor-saving.

[0019] 5. Compared with the traditional cofferdam, the invention is cheaper and only requires anchor rods (support rods), anchor heads, a small amount of NdFeB magnetic rods, PVC, a certain amount of magnetic slurry, etc. Finally, the anchor rod NdFeB magnetic rods above the ground can be recycled through the connector.

[0020] 6. Compared with the traditional cofferdam environment, the present invention has stronger adaptability and more diversified methods. There are corresponding construction methods for hard and soft foundations. In hard geology, a combination of anchor heads and NdFeB magnetic rods is used; in soft and soft geology, anchor heads, anchor rods (support rods) and NdFeB magnetic rods are used, and the anchor rods are used to improve stability; the spacing between the support rods can be expanded and the amount of support rods driven in can be reduced by installing steel plates, but the placement of steel plates is more troublesome than driving in support rods. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0022] Figure 1 This is a diagram showing the matching of the anchor rod (support rod), NdFeB magnetic rod, plastic material layer and connector involved in the present invention.

[0023] Figure 2 This is a diagram showing the matching of the anchor head, NdFeB magnetic rod, plastic material layer and connector involved in the present invention.

[0024] Figure 3 This is a diagram of the interface between the support rod and the magnetic slurry and between the NdFeB magnetic rod and the magnetic slurry involved in the present invention.

[0025] Figure 4 This is a top view of the first cofferdam (enclosed space) involved in the present invention.

[0026] Figure 5 This is a top view of the second cofferdam (enclosed space) involved in the present invention.

[0027] Figure 6 This is a top view of the third type of cofferdam (enclosed space) involved in the present invention.

[0028] Figure 7 (a) and (b) are front views of the cofferdam (enclosed space) involved in the present invention.

[0029] Figure 8 This is a cofferdam diagram of the anchor rod (support rod) involved in the present invention in combination with the steel plate.

[0030] In the figure: anchor rod 1, plastic material layer 2, magnetic slurry 3, NdFeB magnetic rod 5, connector 6, support rod 7, steel plate 8. DETAILED DESCRIPTION

[0031] The embodiments of the present invention are further described below in conjunction with the accompanying drawings.

[0032] Embodiment 1: See also Figure 1-8 A cofferdam structure based on magnetic slurry includes inner and outer structures of different shapes, wherein the inner structure includes an anchor rod 1, which is driven into the water bottom by an anchor driving machine, the anchor rod 1 below the ground is connected to the support rod 7 above the ground by a connector, the support rod 7 is sheathed with a nylon iron boron magnetic rod 5, and the outer layer is wrapped with a plastic material layer 2, and the magnetic slurry 3 is adsorbed on the outer layer wrapped on the plastic material layer 2; or the nylon iron boron magnetic rod 5 is wrapped with a layer of plastic material layer 2 on the outside, which is directly connected to the anchor head driven into the ground through a connector 6, and the magnetic slurry 3 is adsorbed on the plastic material layer 2; the magnetic slurry 3 is adsorbed and solidified to form a closed space 4, and then pile pouring is carried out. After the pile pouring is completed, the connector 6 is rotated to unlock the closed space 4 to dismantle the cofferdam formed by the magnetic slurry 3; the outer structure is a closed protective structure made in the same way as the inner structure. By adopting the surrounding rock structure of the present invention, a closed space is formed after the magnetic slurry is adsorbed, the seawater is isolated from the outside, the dynamic water becomes static water, and then the steel cage is placed. When pouring piles, the steel bars and the concrete mortar can be tightly combined. After the pile pouring is completed, the cofferdam can be disassembled by rotating the unlocking connector.

[0033] Furthermore, the anchor rod 1 below the connector, that is, the part below the ground, is called the anchor rod, and the part above the connector, that is, the part above the ground, is the support rod 7. The above-mentioned anchor rod 1 facilitates the subsequent Furthermore, the anchor rod 1 uses GPS to determine its position, and uses an anchor driver to drive the head of the anchor rod 1 into the water bottom and part of the anchor rod is also inserted into the ground, or the anchor head is driven into the water bottom and connected to the NdFeB magnetic rod 5 with a connector 6 to form a circular, H-shaped or X-shaped figure. The above positioning method can achieve accurate positioning construction of the anchor rod 1.

[0034] Furthermore, the support rod 7 is fixed by placing a hinge-type rotatable steel plate, and the steel plate is welded with a hollow cylindrical hole. The support rod 7 is inserted into the hole, and the magnetic slurry 3 is poured in for reinforcement, and a certain length is reserved to connect with the next steel plate through the solidified magnetic slurry 3. The above structure facilitates the subsequent extension of the cast pile.

[0035] Furthermore, if the water quality of the steel plate is salt water, the corrosion effect of chloride ions on the steel bars needs to be considered. By placing a permanent magnet on one side of the steel plate and pouring magnetic slurry 3 on the other side, the magnetic slurry 3 is attracted to fill the inner wall of the steel plate and isolate water and air from the outside. The above method can play a certain protective role on the steel plate.

[0036] Furthermore, the plastic material layer 2 is made of PVC. Depending on the geological conditions, if the geology is hard, the support rod 7 is not driven in, and the PVC is directly put on the outside of the NdFeB magnetic rod 5; if the geology is soft, a support rod 7 is used, the outer layer is wrapped with PVC, and the NdFeB magnetic rod 5 is put inside the anchor rod 1.

[0037] Furthermore, in soft geology, the NdFeB magnetic rod 5 is sleeved inside the support rod 7 to absorb the magnetic slurry 3 through its strong magnetism; if it is hard geology, the NdFeB magnetic rod 5 is directly connected to the anchor head connector 6 driven into the ground.

[0038] Furthermore, the additive in the magnetic slurry 3 is a 70% water glass solution, which is composed of water, cement, 70% water glass solution and ferromagnetic mineral powder, and the corresponding weight ratio is set to 1:2:1:0.4; Furthermore, the magnetic slurry 3 is poured through a pouring pipe to the support rod 7 or the periphery of the NdFeB magnetic rod 5 for adsorption, and after the magnetic slurry 3 solidifies, a closed space 4 is finally formed; Furthermore, the enclosed space 4 selectively arranges support rods 7 on the water flow impact surface according to the water flow direction and flow velocity to form an arc shape or a rectangle, thereby forming a first line of protection outside the enclosed space 4.

[0039] Furthermore, when the enclosed space 4 is at a deep water level, the length of the support rod 7 or the NdFeB magnetic rod 5 is limited. By first forming a closed space 4 of a certain height, the NdFeB magnetic rod 5 is taken out at the same time for continued use in the enclosed space 4 of the next height. At this time, the water below this height is still water, and the concrete slurry is poured in sections by the conduit method. First, the concrete mortar within this height is poured, and then the enclosed space 4 is formed upwards, and then poured again, and so on, so as to achieve construction while building the cofferdam; Furthermore, the connector 6 can be rotated to unlock and disassemble. It is a metal product with an outer layer covered with PVC material. It is used to connect the anchor rod 1 and the support rod 7 as well as the NdFeB magnetic rod 5 and the anchor head. After the pile pouring is completed, the cofferdam above the ground is rotated to disassemble.

[0040] Embodiment 2: When pouring piles underwater in soft geology, the following steps are included: Method 1: Step 1: Material preparation, prepare the underwater inner and outer periphery, including anchor rods, plastic material layers, magnetic slurry, NdFeB magnetic rods, connectors, and support rods; Step 2: Preparing the support rod in advance. The inside of the support rod is covered with a nepheline iron boron magnetic rod, and the outside is covered with a plastic material layer. Figure 1 As shown; Preferably, the support rods are made of a combination of stainless steel and fiberglass, and fiberglass is used in the portion above sea water, which can save costs and improve corrosion resistance.

[0041] Step 3: Drive the anchor rod, install the connector, use GPS technology to determine the position, use the anchor driver to drive the anchor rod into the water bottom, and use the connector to connect the anchor rod and the support rod. The distance between the support rods is small, and more support rods are driven, and finally a circle, H shape or X shape is formed; In specific operations, choosing to drive anchor rods when the tide is out can improve construction efficiency. The length of the support rods after installation must be higher than the sea level at high tide.

[0042] Step 4: Prepare magnetic slurry, mix cement, water glass and ferromagnetic mineral powder according to the required proportion to make a flowing slurry with magnetic properties and controllable curing time; The ratio of cement, water glass and ferromagnetic mineral powder in the magnetic slurry can be set to 3:1:2. When the construction is carried out at low tide, the ratio of water glass can be reduced and the solidification only needs to be completed before the end of the low tide.

[0043] Step 5: Pour the magnetic slurry through the pouring pipe to the surrounding of the support rod for adsorption. Figure 4-7 As shown, after the magnetic slurry solidifies, a closed space is formed; Preferably, Figure 4-6 As shown, the closed space can selectively arrange support rods on the water flow impact surface according to the water flow direction and flow rate to form an arc or rectangle, forming the first line of protection outside the closed space.

[0044] Step 6: Dismantle the cofferdam made of magnetic slurry. After the pile pouring is completed, rotate and unlock the connector connecting the anchor rod and the support rod, and retrieve the materials above the ground for reuse.

[0045] Method 2: Step 1: Material preparation, making the inner wall, including anchor rods, plastic material layer, magnetic slurry, connectors, support rods, and steel plates; Step 2: Preliminary preparation: wrap a layer of plastic material on the outside of the support rod; Step 3: Prepare magnetic slurry, mix cement, water glass and ferromagnetic mineral powder according to the required proportion to make a flowing slurry with magnetic properties and controllable curing time; Step 4: Drive the anchor rod, place the steel plate, install the connector, use GPS technology to determine the location, use the anchor driver to drive the anchor rod into the water bottom, connect the anchor rod and the support rod with the connector, adjust the angle of the steel plate, and insert the support rod into the hollow cylindrical hole of the steel plate. The steel plate is reserved for a certain length and connected to the next steel plate through magnetic slurry. Figure 8As shown, the spacing between support rods is enlarged, thereby reducing the amount of support rods driven in; Step 5: Anti-corrosion measures. If the water quality of the steel plate is salt water, the corrosion effect of chloride ions on the steel bars needs to be considered. A permanent magnet can be placed on one side of the steel plate, and magnetic slurry can be poured on the other side to attract the magnetic slurry to fill the inner wall of the steel plate and isolate water and air from the outside. Step 6: Dismantle the enclosed space. After the pile pouring is completed, rotate and unlock the connector connecting the anchor rod and the support rod, retrieve the support rod on the ground and pull out the steel plate for reuse.

[0046] Embodiment 3: When pouring piles underwater in hard geology, the following steps are included: Step 1: Material preparation, prepare the underwater inner and outer periphery, including anchor head, magnetic slurry, NdFeB magnetic rod, plastic material layer, connector, and support rod; Step 2: Prepare the NdFeB magnet rod in advance, wrap a layer of plastic material on the outside of the NdFeB magnet rod, the plastic material layer is PVC, and finally Figure 2 As shown; Step 3: Drive the anchor head, install the connector, and use the NdFeB magnetic rod to connect the anchor head driven into the ground through the connector, and finally form a circle, H shape or X shape; Step 4: Prepare magnetic slurry, mix cement, water glass and ferromagnetic mineral powder according to the required proportion to make a flowing slurry with magnetic properties and controllable curing time; The ratio of cement, water glass and ferromagnetic mineral powder in the magnetic slurry can be set to 1:1:2. Due to the influence of water flow, the ratio of water glass is increased to speed up the solidification time of the magnetic slurry.

[0047] Step 5: Pour the magnetic slurry and adsorb the magnetic slurry around the NdFeB magnetic rod through the pouring pipe. Figure 4-7 As shown, after the magnetic slurry solidifies, a closed space is formed; After the closed space is formed, the dynamic water becomes static water, which ensures that the concrete slurry will not be washed away when poured later.

[0048] Preferably, Figure 4-6 As shown, the closed space can selectively arrange support rods on the water flow impact surface according to the water flow direction and flow rate to form an arc or rectangle, forming the first line of protection outside the closed space.

[0049] In particular, when the water level is very deep, the length of the support rods or NdFeB magnetic rods is limited, and they can only form a closed space of a certain height first. At the same time, the NdFeB magnetic rods must be taken out for continued use in the closed space of the next height. At this time, the water below this height is still water, and the conduit method can be used to pour concrete slurry in sections. First, pour the concrete mortar within this height, and then continue to form a closed space upwards, and then pour again, and so on, so as to achieve construction while building the cofferdam.

[0050] Step 6: Dismantle the cofferdam made of magnetic slurry. After the pile pouring is completed, rotate and unlock the connector connecting the NdFeB magnetic rod and the anchor head, and retrieve the materials above the ground for reuse.

Claims

1. A cofferdam structure based on magnetic slurry, characterized in that: The invention comprises an inner peripheral structure and an outer peripheral structure of different shapes. The inner peripheral structure comprises an anchor rod (1) which is driven into the bottom of the water by an anchor driving machine. The anchor rod (1) below the ground is connected to the support rod (7) above the ground by a connector. The support rod (7) is internally sleeved with a nepheline iron boron magnetic rod (5), and the outer layer is wrapped with a plastic material layer (2). The magnetic slurry (3) is adsorbed on the outer layer and wrapped on the plastic material layer (2); or the nepheline iron boron magnetic rod (5) is externally wrapped with a plastic material layer (2), and is directly connected to the anchor head driven into the ground by a connector (6). The magnetic slurry (3) is adsorbed on the plastic material layer (2); the magnetic slurry (3) is adsorbed and solidified to form a closed space (4), and then pile pouring is carried out. After the pile pouring is completed, the connector (6) is rotated to unlock, and the closed space (4) is disassembled to form a cofferdam with the magnetic slurry (3); the outer peripheral structure is a closed protective structure made in the same way as the inner peripheral structure.

2. A cofferdam structure based on magnetic slurry according to claim 1, characterized in that: The anchor rod (1) below the connector, that is, the part below the ground, is called the anchor rod, and the part above the connector, that is, the part above the ground, is the support rod (7).

3. A cofferdam structure based on magnetic slurry according to claim 1, characterized in that: The position of the anchor rod (1) is determined using GPS, and a anchor driving machine is used to drive the head of the anchor rod (1) into the water bottom and a portion of the anchor rod is also inserted into the ground, or the anchor head is driven into the water bottom and connected to a nepheline iron boron magnetic rod (5) using a connector (6) to form a circular, H-shaped or X-shaped pattern.

4. A cofferdam structure based on magnetic slurry according to claim 1, characterized in that: The support rod (7) is fixed by placing a hinge-type rotatable steel plate, and the steel plate is welded with a hollow cylindrical hole. The support rod (7) is inserted into the hole, and the magnetic slurry (3) is poured into it for reinforcement, and a certain length is reserved for connection with the next steel plate through the solidified magnetic slurry (3).

5. A cofferdam structure based on magnetic slurry according to claim 4, characterized in that: If the water in which the steel plate is located is salt water, the corrosion effect of chloride ions on the steel bars needs to be considered. By placing a permanent magnet on one side of the steel plate and pouring magnetic slurry (3) on the other side, the magnetic slurry (3) is attracted to fill the inner wall of the steel plate and isolate water and air from the outside.

6. A cofferdam structure based on magnetic slurry according to claim 4, characterized in that: The plastic material layer (2) is made of PVC. Depending on the geological conditions, if the geology is hard, the support rod (7) is not driven in, and the PVC is directly sleeved on the outside of the NdFeB magnetic rod (5); if the geology is soft, a support rod (7) is used, the outer layer of which is wrapped with PVC, and the NdFeB magnetic rod (5) is sleeved inside the anchor rod (1).

7. A cofferdam structure based on magnetic slurry according to claim 1, characterized in that: In soft geology, the NdFeB magnetic rod (5) is sleeved inside the support rod (7) to absorb the magnetic slurry (3) through its strong magnetism; if the geology is hard, the NdFeB magnetic rod (5) is directly connected to the anchor head connector (6) driven into the ground.

8. The cofferdam structure based on magnetic slurry according to claim 1, characterized in that: The additive in the magnetic slurry (3) is a 70% water glass solution, which is composed of water, cement, 70% water glass solution and ferromagnetic mineral powder, with the corresponding weight ratio being 1:2~2.2:1:0.4~0.5; The magnetic slurry (3) is poured through a pouring pipe onto the support rod (7) or the periphery of the NdFeB magnetic rod (5) for adsorption, and after the magnetic slurry (3) solidifies, a closed space (4) is finally formed; The closed space (4) is selectively provided with support rods (7) on the water flow impact surface according to the water flow direction and flow velocity, forming an arc shape or a rectangle, thereby forming a first line of protection outside the closed space (4).

9. The cofferdam structure based on magnetic slurry according to claim 1, characterized in that: When the enclosed space (4) is at a deep water level, the support rod (7) or the NdFeB magnetic rod (5) is limited in length. A closed space (4) of a certain height is first formed, and the NdFeB magnetic rod (5) is taken out at the same time for continued use in the enclosed space (4) of the next height. At this time, the water below this height is still water. The concrete slurry is poured in sections using the conduit method. The concrete mortar within this height is poured first, and then the enclosed space (4) is formed upwards, and then poured again, and so on, so that construction can be carried out while the cofferdam is being built; The connector (6) is capable of being rotated, unlocked and disassembled. It is made of metal and has an outer layer covered with PVC material. It is used to connect the anchor rod (1) and the support rod (7) as well as the NdFeB magnetic rod (5) and the anchor head. After the pile pouring is completed, the cofferdam above the ground is rotated and disassembled.

10. A construction method of a cofferdam structure based on magnetic slurry according to any one of claims 1 to 9, characterized in that: The following steps are involved: First method: Step 1: Material preparation, making inner and outer structures, including anchor rods (1), plastic material layers (2), magnetic slurry (3), NdFeB magnetic rods (5), connectors (6), and support rods (7); Step 2: Preliminary preparation: in soft geology, a nylon iron boron magnetic rod (5) is sleeved inside the support rod (7), and a layer of plastic material layer (2) is wrapped outside; in hard geology, the support rod (7) is not used, and a layer of plastic material layer (2) is directly wrapped outside the nylon iron boron magnetic rod (5), and the plastic material layer (2) is PVC; Step 3: Solution 1: driving the anchor rod (1), installing the connector (6), using GPS technology to determine the position, using an anchor driving machine to drive the anchor rod (1) into the water bottom in soft geology, and connecting the anchor rod (1) and the support rod (7) with the connector (6). The spacing between the support rods (7) is small, and more support rods (7) are driven, and finally a circular, H-shaped or X-shaped figure is formed; Solution 2: Drive the anchor head and install the connector (6). In the case of hard geology, directly use the nepheline iron boron magnetic rod (5) to connect with the anchor head driven into the ground through the connector (6), and finally form a circular, H-shaped or X-shaped figure; Step 4: preparing magnetic slurry (3), combining cement, water glass and ferromagnetic mineral powder according to required proportions to prepare a flowing slurry with magnetic properties and controllable curing time; Step 5: pouring the magnetic slurry (3), pouring the magnetic slurry (3) onto the support rod (7) or around the NdFeB magnetic rod (5) through a pouring pipe for adsorption, and forming a closed space (4) after the magnetic slurry (3) solidifies; Step 6: Strengthening protection: the closed space (4) can selectively arrange support rods (7) on the water flow impact surface according to the water flow direction and flow velocity, forming an arc or rectangle, and forming the first line of protection outside the closed space (4); Step 7: Dismantle the enclosed space (4), and after the pile pouring is completed, rotate and unlock the above-ground support rod (7) or the connector (6) of the NdFeB magnetic rod (5), and retrieve the above-ground materials for reuse; Second method: Step 1: Material preparation, making the inner perimeter structure, including anchor rods (1), plastic material layer (2), magnetic slurry (3), connectors (6), support rods (7), and steel plates (8); Step 2: Preliminary preparation: wrapping a layer of plastic material (2) on the outside of the support rod (7); Step 3: preparing magnetic slurry (3), combining cement, water glass and ferromagnetic mineral powder according to required proportions to prepare a flowing slurry with magnetic properties and controllable curing time; Step 4: drive the anchor rod (1), place the steel plate (8), install the connector (6), use GPS technology to determine the position, use the anchor driving machine to drive the anchor rod (1) into the bottom of the water, use the connector (6) to connect the anchor rod (1) and the support rod (7), adjust the angle of the steel plate (8), insert the support rod (7) into the hollow cylindrical hole of the steel plate (8), reserve a certain length of the steel plate (8) to connect with the next steel plate (8) through the magnetic slurry (3), expand the spacing between the support rods (7), thereby reducing the driving amount of the support rod (7); Step 5: Anti-corrosion measures. If the water in which the steel plate (8) is located is salt water, the corrosion effect of chloride ions on the steel bars needs to be considered. A permanent magnet is placed on one side of the steel plate (8), and a magnetic slurry (3) is poured on the other side, so that the magnetic slurry (3) is attracted to fill the inner wall of the steel plate (8) and isolate water and air from the outside. Step 6: After the closed space (4) is disassembled and the pile pouring is completed, the connector (6) connecting the anchor rod (1) and the support rod (7) is rotated to unlock, and the support rod (7) on the ground is retrieved and the steel plate (8) is pulled out for reuse.

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