CN114606946A - Ocean pile foundation for reducing installation resistance by electroosmosis method - Google Patents

Abstract

The invention discloses a marine pile foundation for reducing installation resistance by using an electroosmosis method, which comprises a whole marine pile foundation, the whole marine pile foundation comprises a tubular body fixed with the soil at the bottom of the ocean, and an electroosmosis mechanism is arranged at the bottom of the tubular body. The electroosmotic mechanism includes a second electrode, the outer side of the tubular body is the first electrode, the top of the tubular body is provided with a connecting mechanism, the connecting mechanism is electrically connected with the second electrode and the first electrode respectively, and the connecting mechanism is electrically connected with an external power source . The present invention reduces the installation resistance through the electroosmosis method, and can also reverse the electrode for reinforcement. The present invention has high construction efficiency, low construction cost, and guaranteed construction safety.

Description

A marine pile foundation using electroosmosis method to reduce installation resistance

technical field

The invention relates to the field of offshore wind power generation, in particular to a marine pile foundation that uses an electroosmosis method to reduce installation resistance.

Background technique

The development strategies of many countries in the world have begun to focus on vigorously developing wind power generation. With the development of wind power, its cost performance is forming a competitive advantage with coal power and hydropower. With the unification of wind power installed capacity and the scale of power generation, the cost of wind power is expected to drop further. At the same time, with the development and utilization of marine resources, offshore structures such as offshore wind turbines are being built one after another. At present, the pile foundation structure often adopts a single pile foundation structure. Due to horizontal loads such as horizontal seismic force and ship impact force, the design depth and diameter of the pile foundation structure are large. At present, the installation of offshore wind power monopiles often uses pile hammers to push the foundation to the ground, applying a series of axial impacts to push the foundation down into the soil. When it is driven, the foundation is replaced by foundation piles, which compress the surrounding soil and increase the axial friction along the foundation, which in turn increases the foundation's axial bearing capacity.

However, the shear force to be overcome is very high and some problems can easily arise during the construction of the monopile. First, the high impact forces required for piling impose significant mechanical demands on the foundation itself to avoid failure during installation. Additionally, the noise from impacts can be very high. As far as offshore installations are concerned, this poses a very serious environmental hazard to marine life. In this regard, the installation of offshore structures may have detrimental physical and behavioral impacts on marine wildlife. Significant efforts have been made in recent years to mitigate the noise generated during such installations. For example, bubble curtains are often required around piling sites to reduce noise from the piling site. However, the use of such noise mitigation measures can place a considerable burden on the installation of marine structures. For example, if a bubble curtain needs to be set up for each pile location, the overall installation time will increase significantly. Furthermore, the costs involved in providing a bubble curtain and a separate bubble curtain container are substantial, adding significantly to the cost of offshore wind farm installations.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a marine pile foundation that uses electroosmosis method to reduce installation resistance, so as to solve the above-mentioned problems in the prior art.

In order to achieve the above purpose, the present invention provides the following solutions: the present invention provides a marine pile foundation for reducing installation resistance by using an electroosmosis method, including the marine pile foundation as a whole, and the marine pile foundation as a whole includes a soil fixed connection with the bottom of the ocean. A tubular body, the bottom of the tubular body is provided with an electroosmosis mechanism, the electroosmosis mechanism includes a second electrode, the outer side of the tubular body is a first electrode, and the top of the tubular body is provided with a connection mechanism, so The connection mechanism is electrically connected to the second electrode and the first electrode respectively, and the connection mechanism is electrically connected to an external power source.

Preferably, the electroosmotic mechanism further comprises a groove symmetrically arranged on the outer side surface of the bottom of the tubular body, an insulating layer is provided in the groove and on the outer side of the groove, and the second electrode is fixedly connected to the groove. On the outside of the insulating layer, a gap is provided between the second electrode and the soil.

Preferably, the depth of the gap is 0.5-1 cm.

Preferably, a resistive coating is provided on the outside of the tubular body close to the groove.

Preferably, the connection mechanism includes a first terminal and a second terminal fixed on one side of the top of the tubular body, the first terminal and the second terminal are located above the sea level, the first terminal and The second terminals are respectively electrically connected to the external power source, the second electrodes are electrically connected to the second terminals, and the first electrodes are electrically connected to the first terminals.

Preferably, a wind turbine is fixed on the top surface of the tubular body.

Preferably, the second electrode is located outside the insulating layer.

Preferably, an installation method for marine pile foundations using electroosmosis to reduce installation resistance, comprising the following steps:

a. Connect the second electrode to the positive electrode of the external power supply through the second terminal, so that the second electrode acts as an anode;

b. Connect the first electrode to the negative electrode of the external power supply through the first terminal, so that the first electrode can function as a cathode;

c. Insert the lower end of the tubular body structure into the soil, and apply a potential difference between the first electrode and the second electrode to generate an electroosmotic effect, attract the water in the soil to the first electrode, and promote the insertion of the tubular body base into the soil .

The present invention discloses the following technical effects: the present invention reduces installation resistance through electroosmosis, and can also reverse electrodes for reinforcement; the present invention has high construction efficiency, low construction cost, guaranteed construction safety, and can reduce noise during installation Pollution.

Description of drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings required in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some of the present invention. In the embodiments, for those of ordinary skill in the art, other drawings can also be obtained according to these drawings without creative labor.

Fig. 1 is the structural representation of the marine pile foundation that utilizes electroosmosis method to reduce installation resistance of the present invention;

Fig. 2 is the structural representation in the groove;

3 is a schematic structural diagram of a plurality of second electrodes in Example 2;

4 is a schematic structural diagram of a fluid channel in Example 2;

Among them: 1. Overall marine pile foundation; 2. Soil; 3. Upper end of structure; 4. Tubular body; 5. Lower end of structure; 6. Groove; 7. Second electrode; 8. Outer side; 9. Inner side; 10 11, gap; 12, resistive coating; 20, fluid conduit; 21, fluid port; 30, wind turbine; 40, first terminal; 41, second terminal.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

In order to make the above objects, features and advantages of the present invention more clearly understood, the present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments.

Example 1

1-2, the present invention provides a marine pile foundation utilizing electroosmosis method to reduce installation resistance, comprising an integral marine pile foundation 1, and the integral marine pile foundation 1 includes a tubular body 4 fixed to the soil 2 at the bottom of the ocean, The bottom of the tubular body 4 is provided with an electroosmosis mechanism, the electroosmosis mechanism includes a second electrode 7, the outer side 8 of the tubular body 4 is the first electrode, and the top of the tubular body 4 is provided with a connection mechanism, so The connection mechanism is electrically connected to the second electrode 7 and the first electrode respectively, and the connection mechanism is electrically connected to an external power source.

Both electrodes are located on the tubular body 4, which avoids the need to provide electrodes at sea level, which can create a potential difference between different areas of the tubular body 4, resulting in electroosmosis. At the same time, since both electrodes are located on the tubular body 4, the distance between the electrodes is shorter, so only a lower voltage is required to generate electroosmosis. Therefore, during the installation process in which the groove 6 is the anode and the outer side 8 of the tubular body 4 is the cathode, the water in the surrounding soil is attracted to the surface of the tubular body 4 to soften the soil 2 and form a lubricating film on the side of the tubular body 4, It is easier to tie the tubular body 4 into the foundation. Therefore, the hammering energy can be effectively reduced; when the problem of hammer rejection is encountered in piling, the problem of hammer rejection can be effectively solved; when the pile is driven to the design depth, the current direction can be reversed, and the soil consolidation near the second electrode 7 can be accelerated by electroosmosis Drainage, enhance soil strength, improve the overall bearing capacity of foundation piles, this design overcomes the defect of limited hammering energy, reduces installation resistance, ensures the effective sinking of the pile foundation to the design depth, and reduces the overall piling cost. When the shear resistance between the tubular body 4 and the side surface of the tubular body 4 is reduced, the marine pile foundation monolith 1 can be driven into the soil 2 more easily, therefore, the completion of the installation requires a lower number of impacts or Lower impact force, thus reducing noise, thus avoiding the need for additional noise reduction measures.

To further optimize the solution, the electroosmotic mechanism also includes a groove 6 symmetrically arranged on the outer side surface 8 of the bottom of the tubular body 4, and an insulating layer 10 is provided in the groove 6 and on the outside of the groove 6, and the second The electrode 7 is fixed on the outer side of the insulating layer 10 to insulate the second electrode 7 from the tubular body 4 , and a gap 11 is provided between the second electrode 7 and the soil 2 .

In a further optimized solution, a gap 11 is formed between the side surface of the second electrode 7 and the plane defined by the outer side surface 8 of the tubular body 4 . The depth of the gap 11 is 0.5-1 cm. At the same time, when the structural lower end 5 of the tubular body 4 seeps into the soil 2 from the seawater above, the water will be left in this gap 11, and in addition, in the absence of an electric field, the pore water in the surrounding soil 2 may also migrate to the in the gap. In this way, when the ground is pushed down, the water in the soil 2 and the water in the seabed can then drain into this gap 11 to establish an electrolytic connection.

Further optimization scheme, the outer side of the tubular body 4 close to the groove 6 is provided with a resistance coating 12, and the resistance coating 12 is arranged on the outer side 8 of the tubular body 4, extending vertically to any side of the second electrode 7 .

The resistive coating 12 serves to adjust the electric field strength between the first electrode and the second electrode 7 . When a potential difference is applied across the electrodes, the resistive coating 12 acts to extend the electric field path around the resistive coating 12 . Thus, this avoids the generation of excessively high field strengths in the region directly adjacent to the junction between the second electrode 7 and the tubular body 4, since the distance between the electrodes is small, which would otherwise allow water to evaporate. In this way, the taper of the resistance can be used to gradually counteract the increased electric field strength due to proximity to achieve a more uniform electric field extending from the second electrode 7 .

In a further optimized solution, the connection mechanism includes a first terminal 40 and a second terminal 41 fixed on one side of the upper end 3 of the tubular body 4, and the first terminal 40 and the second terminal 41 are respectively connected to the external power supply. For electrical connection, the second electrode 7 is electrically connected to the second terminal 41 through wiring (not shown in the figure), and the first electrode is electrically connected to the first terminal 40 .

In a further optimized solution, a wind turbine 30 is fixed on the top surface of the tubular body 4 .

The wind turbine 30 includes: a generator assembly for wind power generation, and a monopile formed by the above-mentioned marine pile foundation integral 1 supporting the generator assembly. The tubular body 4 in this design is an elongated hollow tubular shape with a length of more than 10 meters or 20 meters. Meter. A monopile utilizing the tubular body 4 may provide a foundation for the wind turbine 30 on which the nacelle and rotor of the wind turbine generator assembly are supported, and the wind turbine 30 may be installed offshore. When installing the wind turbine 30 , the tubular body 4 of the marine pile monolith 1 is positioned on the installation part by the pile-driven drilling rig, with its structural lower end 5 slightly submerged in the soil 2 . Once the second electrode 7 is covered by the soil 2, a DC power source on the mounting part (not shown in the figure) can be used to apply a potential difference through the first terminal 40 and the second terminal 41 . The tubular body 4 is grounded, and a positive voltage of about +80V is applied to the second electrode 7 . This results in a potential difference of +80V between the second electrode 7 and the tubular body 4, creating an electric field through the soil between them. The single pile using the above-mentioned tubular body 4 is based on the traditional offshore impact hammer piling, adding electroosmosis technology to assist in weakening the friction resistance of the pile-soil contact surface during the piling process, and excavating a shallower layer at the fixed position on the surface of the hollow pile as a In the groove 6, after laying the insulating layer 10, the electrode plate is arranged to set the anode electrode, and the DC power supply is turned on to form an electroosmotic field. The water near the groove 6 flows to the outside of the single pile of the tubular body 4, which can reduce the pile-soil contact surface. At the same time, the flow of water will form a water film, which can reduce the friction coefficient, and the friction resistance of the pile-soil contact surface can be greatly reduced in two aspects.

In a further optimized solution, the second electrode 7 is located outside the insulating layer 10 .

Further optimization scheme, an installation method of marine pile foundation using electroosmosis method to reduce installation resistance, comprising the following steps:

a. Connect the second electrode 7 to the positive electrode of the external power supply through the second terminal 41, so that the second electrode 7 functions as an anode;

b. The first electrode is connected to the negative electrode of the external power supply through the first terminal 40, so that the first electrode acts as a cathode;

c. Insert the lower end of the tubular body 4 into the soil 2, and apply a potential difference between the first electrode and the second electrode 7 to generate an electroosmotic effect, attract the water in the soil 2 to the first electrode, and promote the tubular body 4 Insert soil 2.

During the driving phase of the installation, a positive voltage of about +40V to +400V is applied to the second electrode 7 . When the voltage is below about +80V, the voltage is below a dangerous level. Meanwhile, the tubular body 4 is grounded with a potential of 0V, thereby serving as a cathode. In this way, since the potential of the tubular body 4 itself is zero, contact during installation does not pose a safety hazard. That is, the underlying charged area is isolated to the upper end of the tubular body 4 at the second electrode 7 , which is buried under the soil 2 .

In some locations with particularly soft moist clay, the electroosmotic effect may be sufficient to allow the marine pile monolith 1 to be driven into the soil 2 using ballast alone.

A method for stabilizing an installed marine pile foundation according to the above method, the method comprising:

a. Connect the second electrode 7 to the negative electrode of the power supply for the second electrode 7 to serve as a cathode;

b. Connect the first electrode to the positive pole of the power supply, so that the first electrode acts as an anode;

c. A potential difference is applied between the first electrode and the second electrode 7 to generate an electroosmotic effect, thereby repelling the water in the soil 2 to a position away from the first electrode. In this way, the soil around the foundation can be dehydrated to enhance the shear strength between the foundation and the soil. This allows the foundation to stabilize. In addition, the stabilization process also helps to at least partially neutralize the acidity that may develop in the soil 2 during installation. That is to say, by using the second electrode 7 as a cathode, OH- ions are generated in the pore water of the surrounding soil 2, which can neutralize the H+ remaining in the installation process.

A method according to the above-mentioned adjustment of the marine pile foundation that has been inserted into the soil, the method comprising:

a. Connect the second electrode 7 to the positive pole of the power supply of the second electrode 7 to function as an anode;

b. Connect the first electrode to the negative pole of the power supply, so that the first electrode acts as a cathode;

c. Apply a potential difference between the first electrode and the second electrode 7 to generate an electroosmotic effect to attract the water in the soil 2 to the first electrode; move the main body in the soil 2 . In this way, the foundation can be adjusted more easily, eg allowing the foundation to be retracted from the soil 2 . This method can also be used to adjust the position of foundations, for example to reset foundations that have moved due to extreme loads.

Once the structural lower end 5 has reached the desired depth, the shear strength between the soil 2 and the sides of the tubular body 4 can be restored by switching off the external power supply. This stops the electroosmotic effect and stabilizes the foundation by reducing its lubrication. However, this stabilization takes time. This is because clay has very low permeability, so excess pore pressure next to the foundation can take time to dissipate back into soil 2 . Stability can optionally be further enhanced by temporarily reversing the polarity of the power supply, where the tubular body 4 acts as the anode and the second electrode 7 acts as the cathode. This reverses the electric field, thereby expelling pore water from the outer side 8 of the tubular body 4 , thereby enhancing the adhesion strength of the interface between the tubular body 4 and the soil 2 .

Example 2

The difference from Embodiment 1 is that, referring to FIGS. 3-4 , this embodiment can further install a plurality of second electrodes 7 on the marine pile foundation, which also includes corresponding grooves 6 for when the tubular body 4 is inserted into the soil 2 . , forming a plurality of gaps 11 between the second electrodes 7 and the soil 2 . A plurality of second electrodes 7 and associated grooves 6 are provided on the tubular body 4 , and the function of each second electrode 7 is the same as that of the second electrode 7 in the first embodiment. The first group of second electrodes 7 is disposed toward the lower end 5 of the structure of the tubular body 4 , and is located on the side surfaces of the outer side surface 8 and the inner side surface 9 . Further above the vertical length of the tubular body 4, a second set of second electrodes 7 is provided, also mounted on the outer 8 and inner 9 sides. In this way, a plurality of second electrodes 7 can be provided on the tubular body 4, producing an electroosmotic effect over a larger area. During construction, a plurality of second electrodes 7 may be selectively activated to limit their operation until the respective second electrodes 7 are below the soil 2 surface. At the same time, a plurality of second electrodes 7 and associated grooves 6 may be arranged on the tubular body 4 in different vertical horizontal positions. The plurality of second electrodes 7 may also be configured at different potentials. For example, the electrode potentials inside and outside the hollow tubular body 4 can be adjusted to provide different degrees of lubrication between the surfaces. In order to avoid short circuits during the initial stages of installation when the second set of second electrodes 7 are still above the soil 2, a switch may be provided to disconnect the second set of second electrodes 7 from the power circuit. Thus, the second set of second electrodes 7 can remain uncharged until below the soil 2 line, after which they can be connected to the power circuit to create an electroosmotic effect in this area. After installation, the foundation can be stabilized by reversing the polarity of the power supply, so that the second electrode 7 acts as a cathode, and the pore water is kept away from the anode outer side 8 of the tubular body 4 .

Also provided in the tubular body 4 are fluid conduits 20 , which feed the tubular body 4 downward through manifolds formed within the tubular body 4 and openings at fluid ports 21 provided on the sides of each second electrode 7 . of the inner side 9.

The fluid conduit 20 allows fluid to be delivered or drained from the second electrode 7, and the inner bore of the fluid conduit 20 is electrically insulated from the tubular body 4 to avoid short circuits through the fluid. This electrical isolation need not extend throughout the system, but only to adequately limit or avoid short circuits. As described above, in the basic driving process, when the second electrode 7 acts as an anode and the tubular body 4 acts as a cathode, pore water is driven from the second electrode 7 and attracted to the surface of the tubular body 4 . This has the effect of dehydrating the soil 2 near the second electrode 7 . Thus, the fluid conduit 20 allows water from the fluid port 21 to rehydrate the gap 11 and the adjacent soil 2 . This can be achieved by opening the proximal end of the fluid conduit 20 to seawater, allowing seawater to be drawn into the gap 11 . Alternatively a pumping system may be provided to deliver water to the gap 11 . The delivery of water to the gap 11 first helps to maintain the electrolyte connection between the anode and cathode, thereby ensuring the electroosmotic flow of water to the cathode tubular body 4 . Secondly, the pumped water also acts to keep the soil 2 closed to the gaps 11 formed by the grooves 6 in the tubular body 4 . In the absence of water at the fluid port 21, the soil 2 may re-enter the gap 11 due to the relaxation of the elastic half space or the vacuum effect created by the drainage of the water from the anode. Therefore, the water pumped from the fluid port 21 may help avoid any localized sticking at the anode. Additives can also be introduced, pumped into the fluid water from fluid port 21 to enhance its electrical conductivity or provide chemical stability, both ports can be used to circulate water or electrolyte. Installation may also be completed by providing grout or similar material to seal the piping system and displace any remaining water trapped in gap 11 .

In this case, fluid delivery at fluid port 21 can be used to neutralize or dilute the acidity generated at the anode. In addition to the electroosmotic effect, the electric field in soil 2 also induces other electrokinetic effects in the surrounding environment. In particular, _H2 and OH- are generated by cathodic electrolysis, and _O2 and H+ are generated at the anode and then migrate to each other. However, since H+ has a higher mobility than OH- ions, acidity usually dominates the surrounding soil chemistry. The acidity in soil 2 may be detrimental to biodegradation, while also accelerating the erosion of the ground itself. Thus, a chemically stabilizing fluid can be pumped from fluid port 21 to neutralize or dilute the positively charged H+ ions. For example, lime or calcium chloride solutions can be used as stabilizers. This also restores the potential to maintain the electroosmotic effect that might otherwise be diminished.

As a feature of the fluid conduit 20, fluid can also be drained from the second electrode 7 in stable operation. When the foundation reaches the desired depth, the polarity of the power source can be reversed, attracting water to the second electrode 7, which acts as a cathode. As the pore water migrates to this area, the fluid conduit 20 can be pumped to draw water through the fluid port 21 and discharge up the system into the sea. Therefore, the soil 2 around the entire marine pile foundation 1 can be dehydrated to stabilize it. As another feature of the fluid conduit 20, a consolidated or hardened material may be delivered through the fluid port 21 to strengthen the foundation. For example, in the final stages of installation, the cementing suspension can be pumped from fluid port 21 . This may displace water in the gap 11, which might otherwise soften the soil 2 around the second electrode 7 over time. At the same time, this cementing suspension can also combine with surrounding soil particles to form areas of hardened cement adjacent to the foundation. For example, materials that are used as glue or to change the salinity of the soil 2 itself to increase the strength of the clay can be used to reinforce the foundation.

In the description of the present invention, it should be understood that the terms "portrait", "horizontal", "upper", "lower", "front", "rear", "left", "right", "vertical", The orientation or positional relationship indicated by "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention, rather than indicating or It is implied that the device or element referred to must have a particular orientation, be constructed and operate in a particular orientation, and therefore should not be construed as limiting the invention.

The above-mentioned embodiments are only to describe the preferred mode of the present invention, but not to limit the scope of the present invention. Without departing from the design spirit of the present invention, those of ordinary skill in the art can Variations and improvements should fall within the protection scope determined by the claims of the present invention.

Claims (8)

1. The utility model provides an utilize electric osmosis method to reduce ocean pile foundation of installation resistance which characterized in that: including the whole (1) of ocean pile foundation, the whole (1) of ocean pile foundation includes the siphonozooid (4) with soil (2) rigid coupling of ocean bottom, the bottom of siphonozooid (4) is equipped with the electroosmosis mechanism, the electroosmosis mechanism includes second electrode (7), lateral surface (8) of siphonozooid (4) are first electrode, the top of siphonozooid (4) is equipped with coupling mechanism, coupling mechanism respectively with second electrode (7) with first electrode electric connection, coupling mechanism and external power source electric connection.

2. The marine pile foundation for reducing installation resistance using electroosmosis of claim 1, wherein: the electroosmosis mechanism further comprises a groove (6) symmetrically arranged on the outer side face (8) of the bottom of the tubular body (4), an insulating layer (10) is arranged in the groove (6) and on the outer side of the groove (6), the second electrode (7) is fixedly connected to the outer side of the insulating layer (10), and a gap (11) is formed between the second electrode (7) and the soil (2).

3. The marine pile foundation utilizing electroosmosis to reduce installation resistance of claim 2, wherein: the depth of the gap (11) is 0.5-1 cm.

4. The marine pile foundation utilizing electroosmosis to reduce installation resistance of claim 3, wherein: and a resistance coating (12) is arranged on the outer side of the tubular body (4) close to the groove (6).

5. The marine pile foundation for reducing installation resistance using electroosmosis of claim 1, wherein: the connection mechanism comprises a first terminal (40) and a second terminal (41) which are fixedly connected to one side of the top of the tubular body (4), the first terminal (40) and the second terminal (41) are located on the sea level, the first terminal (40) and the second terminal (41) are respectively electrically connected with an external power supply, the second electrode (7) is electrically connected with the second terminal (41), and the first electrode is electrically connected with the first terminal (40).

6. The marine pile foundation for reducing installation resistance using electroosmosis of claim 1, wherein: and a wind turbine (30) is fixedly connected to the top surface of the tubular body (4).

7. The marine pile foundation utilizing electroosmosis to reduce installation resistance of claim 2, wherein: the second electrode (7) is located outside the insulating layer (10).

8. A method for installing an ocean pile foundation by using an electroosmosis method to reduce installation resistance comprises the following steps:

a. connecting the second electrode (7) to the positive electrode of an external power supply via a second terminal (41), with the second electrode (7) functioning as an anode;

b. connecting the first electrode to a negative pole of an external power source through a first terminal (40) so that the first electrode functions as a cathode;

c. the structural lower end (5) of the tubular body (4) is inserted into the soil (2) and a potential difference is applied across the first and second electrodes (7) to create an electroosmotic effect, drawing water from the soil (2) onto the first electrode, facilitating insertion of the tubular body (4) into the soil (2).

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