A method for treating underwater soft soil foundations using a combination of electroosmosis and vacuum preloading

Abstract

This invention proposes a method for treating underwater soft soil foundations using a combined electroosmotic and vacuum preloading system. The system comprises an electric water-blocking system and an electroosmotic-vacuum drainage system. The electric water-blocking system is positioned above and beside the electroosmotic-vacuum drainage system. When the electroosmotic-vacuum drainage system drains water from the electroosmotic-vacuum drainage area, pore water moves from the anode to the cathode under the influence of an electric field and vacuum pressure, and is discharged through a vacuum pump. The electric water-blocking system includes a horizontal and a vertical water-blocking strip constructed with conductive drainage plates or metal electrodes. A potential gradient opposite to the hydraulic gradient around the drainage and consolidation treatment area is formed between the cathode and anode, thus isolating the drainage and consolidation treatment area from the surrounding water bodies and preventing backflow of water from the surrounding area during drainage by the electroosmotic-vacuum drainage system. This invention is easy to construct, has good water-blocking effect, and can effectively achieve drainage and consolidation of underwater soft soil.

Description

Technical Field

[0001] This invention relates to the field of underwater soft soil foundation reinforcement technology in civil engineering, and in particular to a method for treating underwater soft soil foundations using a combination of electroosmosis and vacuum preloading. Background Technology

[0002] Unlike onshore foundations, underwater soft soil foundation treatment has the following characteristics: high initial pore water pressure; lower soil strength; higher requirements for construction equipment and consideration of reinforcement depth; higher requirements for waterproofing during construction; complex construction environment, easily affected by climate, and more interfering factors, etc. With the continuous development of my country's economy and society, the requirements for underwater foundation treatment in numerous cross-sea bridges, nearshore and offshore marine engineering projects are becoming increasingly stringent, which has also promoted the rapid development of underwater foundation treatment technology in my country. Currently, the drainage consolidation method commonly used for underwater soft soil treatment is vacuum preloading.

[0003] The principle of underwater vacuum preloading is similar to that of onshore vacuum preloading. This method involves first installing a vertical conductive drainage board, then laying a sealing membrane and geotextile on top to achieve a seal. A vacuum pump then creates negative pressure inside and outside the membrane, expelling water and gas from the soil and stabilizing it. However, underwater vacuum preloading currently faces several major problems: underwater vacuum membrane installation requires advanced technology, and leakage is frequent; construction is inconvenient and time-consuming; drainage boards are prone to clogging; vacuum levels decrease significantly with soil depth; vacuum levels decrease with increasing water pressure over the membrane (studies show that the vacuum effect drops significantly when the water depth exceeds 5m); furthermore, the effectiveness of vacuum preloading drainage is sensitive to hydraulic permeability and is ineffective for treating low-permeability soft soils.

[0004] Electroosmotic consolidation involves applying an electric current to electrodes inserted into the soil to create an electric field. Under the influence of this field, pore water flows from the anode to the cathode and is discharged from the cathode, thus achieving drainage consolidation. This method has the following advantages: it is safe and environmentally friendly; it is not limited by the hydraulic permeability coefficient, has high drainage efficiency, and is particularly advantageous for ultrafine-grained soft soils; and it does not cause instability due to insufficient bearing capacity in soft soil foundations. Currently, the application of electroosmotic consolidation is limited to terrestrial soft soils, and there is no related research or application of electroosmotic consolidation for underwater soft soils. Unlike terrestrial soft soil drainage consolidation, underwater soft soils are connected to the overlying water body. Therefore, the key to underwater soft soil consolidation is how to isolate the overlying water body from the soft soil in the treatment area. If the terrestrial electroosmotic consolidation technology is directly applied to the consolidation treatment of underwater soft soils, water will inevitably flow back into the electroosmotic treatment area, leading to the failure of the electroosmotic consolidation treatment. Therefore, it is necessary to develop an easy-to-construct, efficient, and stable underwater soft soil foundation treatment method. Summary of the Invention

[0005] This invention proposes a method for treating underwater soft soil foundations using a combination of electroosmosis and vacuum preloading. It is suitable for reinforcing underwater soft soil, especially for underwater low-permeability soft clay foundations with deep mud surfaces and thick soft soil layers. This method is easy to construct, has good water-proofing effect, and can effectively achieve drainage and consolidation of underwater soft soil.

[0006] The present invention adopts the following technical solution.

[0007] An underwater soft soil foundation treatment method combining electroosmosis and vacuum preloading is disclosed for treating pore water in a drainage consolidation treatment area. The method utilizes an electroosmosis combined with vacuum preloading system comprising an electric water-blocking system and an electroosmosis-vacuum drainage system. The electric water-blocking system is positioned above and beside the electroosmosis-vacuum drainage system. When the electroosmosis-vacuum drainage system drains water from the electroosmosis-vacuum drainage area, the pore water in the drainage consolidation treatment area moves from the anode to the cathode under the influence of an electric field and vacuum pressure and is discharged through a vacuum pump. The electric water-blocking system includes a horizontal water-blocking strip and a vertical water-blocking strip constructed with conductive drainage plates or metal electrodes. A potential gradient opposite to the hydraulic gradient around the drainage consolidation treatment area is formed between the cathode and anode to create isolation between the drainage consolidation treatment area and the surrounding water body, preventing backflow of water from the surrounding area during drainage by the electroosmosis-vacuum drainage system.

[0008] The electric water-stop system includes a horizontal electric water-stop system (3) and a vertical electric water-stop system (4) around the electroosmotic-vacuum drainage area. The horizontal electric water-blocking system consists of one or more horizontal cathode conductive drainage plates (3-1), one or more horizontal anode conductive drainage plates (3-2), cables (5), switches (6) and a first power supply (7-1); the horizontal cathode conductive drainage plates and the horizontal anode conductive drainage plates are placed on the surface of the soft soil foundation mud surface and connected to the first power supply, and the horizontal projections of the cathode and anode formed therein are staggered or perpendicularly intersecting; The vertical electric water-proof system consists of one or more vertical water-proof cathode plates (4-1), one or more vertical water-proof anode plates (4-2), cables (5), switches (6) and a second power supply (7-2); The vertical water-proof cathode plate and the vertical water-proof anode plate are vertically inserted into the deep part of the soft soil foundation; the vertical water-proof cathode plate is connected to the second power source through a cable and a switch; the vertical water-proof anode plate is connected to the second power source through a cable and a switch.

[0009] The vertical distance d1 between the horizontal cathode conductive drainage plate and the horizontal anode conductive drainage plate is between 0.5 and 1 m. The spacing d2 between each horizontal cathode conductive drainage plate and between each horizontal anode conductive drainage plate is between 0.4 and 0.6 m. The horizontal projection of the horizontal electric water-proof system completely covers the electroosmotic-vacuum drainage area (14) and the vertical electric water-proof system, and the extension distance d3 of the projection is at least 2m greater than the vertical water-proof cathode plate. The vertical distance d4 between the horizontal electric water-stop system and the vertical electric water-stop system is 0.2 to 0.5 m; Each vertical water-proof cathode plate is placed around the vertical water-proof anode plate, and the spacing between each vertical water-proof cathode plate is d6. The width d5 ​​of the vertical conductive drainage plate is approximately 0.1m. D1 = d5 + d6, and D1 is between 0.5 and 1m.

[0010] The electroosmosis-vacuum drainage system (8) consists of multiple vertical cathode conductive drainage plates (8-1), multiple vertical anode conductive drainage plates (8-2), cables (5), switches (6), a third power supply (7-3), a delivery pipe (9), valves (10), a water vapor separation device (11), and a vacuum pump (12). The vertical cathode conductive drainage plate and the vertical anode conductive drainage plate are vertically inserted into the deep soil of the electroosmosis-vacuum drainage area; the vertical cathode conductive drainage plate and the vertical anode conductive drainage plate are connected to the negative terminal and the anode of the third power source respectively through cables and switches; The vertical cathode conductive drainage plate is connected to the vacuum pump via a delivery pipe, valve, and water vapor separation device.

[0011] The distance d7 between the cathode and anode formed by the vertical cathode conductive drainage plate and the vertical anode conductive drainage plate is between 1 and 1.5 m; the distance from the bottom of the projection of the vertical cathode conductive drainage plate at the vertical water-proof anode plate to the bottom of the vertical water-proof anode plate is d8, and d8 is between 0.3 and 0.5 m.

[0012] The vertical cathode conductive drainage plate and the vertical anode conductive drainage plate are arranged in an array in the underwater soft soil area of ​​the electroosmosis-vacuum drainage zone. The outermost ring of the array is the cathode, and the inner ring is distributed in the order of "cathode-anode".

[0013] The top-view layout shape of the array includes a rose-shaped layout, a parallel staggered layout, or a rose-shaped layout.

[0014] The electrode materials of the electroosmotic-vacuum drainage system and the electric water-stop system are electric geosynthetic materials; in the electric water-stop system, the horizontal conductive drainage board is an electric drainage board, and the vertical conductive drainage board is an electric drainage board or an electric drainage pipe.

[0015] When using an electroosmosis combined with vacuum preloading system to treat underwater soft soil foundations, the energizing methods include continuous energizing, intermittent energizing, or staged energizing, and the vacuuming methods include continuous vacuuming, intermittent vacuuming, or staged vacuuming.

[0016] The method is an underwater soft soil foundation treatment method based on electroosmosis combined with vacuum preloading. The construction sequence during implementation includes the following steps. Step S1: First, install vertical cathode conductive drainage plates and vertical anode conductive drainage plates in the electroosmosis-vacuum drainage area; select the layout of the vertical conductive drainage plates according to specific circumstances. Step S2: Lay out the delivery pipe, arrange the water vapor separation device and arrange the vacuum pump to form the vacuum drainage system of the electroosmosis-vacuum drainage system, wherein the delivery pipe is connected to the vertical cathode conductive drainage plate; lay out the electroosmosis system including the cable and power supply of the electroosmosis-vacuum drainage system, wherein the vertical cathode conductive drainage plate and the vertical anode conductive drainage plate are respectively connected to the negative and positive terminals of the third power supply. Step S3: In the vertical electric water-proof system of the electric water-proof system, install a vertical water-proof cathode plate and a vertical water-proof anode plate, and connect the vertical water-proof cathode plate and the vertical water-proof anode plate to the negative and positive terminals of the second power supply respectively through cables. Step S4: In the horizontal electric water-stop system of the electric water-stop system, lay horizontal cathode conductive drainage boards and horizontal anode conductive drainage boards. Select the layout of the horizontal conductive drainage boards according to specific conditions, and connect the horizontal cathode conductive drainage boards and horizontal anode conductive drainage boards to the negative and positive terminals of the first power supply respectively through cables. Step S5: After the horizontal cathode conductive drainage board is laid, let it stand for a period of time to allow it to come into close contact with the soil.

[0017] The method proposed in this invention is mainly used for the treatment of underwater soft soil foundations, especially soft soil foundations in deep water areas. During the electroosmotic-vacuum preloading drainage process, pore water in the drainage consolidation treatment area moves from the anode to the cathode under the action of an electric field and vacuum pressure, and is then extracted by a vacuum pump. A negative excess pore water pressure is generated at the anode between the water-blocking area and the drainage consolidation treatment area. Without a water-blocking system, the surrounding water would flow back. However, under the action of the electroosmotic water-blocking system described in this invention, a potential gradient opposite to the hydraulic gradient (direction from the anode to the cathode) is formed between the anode and cathode, preventing backflow and isolating the treatment area from the surrounding water body. The surrounding water will not re-enter the soil in the treatment area. The soil in the drainage consolidation treatment area is effectively treated under electroosmotic-vacuum preloading, thereby achieving drainage consolidation of underwater soft soil.

[0018] This invention provides a method for treating underwater soft soil foundations using a combination of electroosmosis and vacuum preloading, belonging to the field of underwater foundation treatment technology in civil engineering. The electroosmosis combined with vacuum preloading system includes an electroosmosis water-blocking system and an electroosmosis-vacuum drainage system. The water-blocking system isolates the treatment area from the water body, facilitating electroosmosis-vacuum drainage consolidation in the treatment area. This invention solves the problems of difficult vacuum membrane installation and easy leakage in traditional vacuum preloading technology. This invention is suitable for reinforcing underwater soft soil foundations, especially soft soil foundations in deep water areas.

[0019] The beneficial effects of this invention are as follows: 1. This invention uses conductive drainage boards or metal electrodes to construct horizontal and vertical water-proof strips, which is convenient to construct (no need to lay vacuum membranes, avoiding the problems of difficult construction and frequent leakage of vacuum membranes) and has a good water-proof effect.

[0020] 2. This invention is not limited by water depth. Especially for deep water areas, it can effectively avoid the problem of large vacuum loss caused by the overlying water pressure in traditional vacuum pre-compression methods.

[0021] 3. This invention combines electroosmosis with vacuum preloading, which can solve the problems of drainage board clogging and vacuum degree loss as soil depth increases in the vacuum preloading method alone. Attached Figure Description

[0022] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments: Appendix Figure 1 This is a front view schematic diagram of the present invention; Figure 2 This is a side view of the present invention (waterproof layers are arranged in a cross pattern). Figure 3 This is a top view schematic diagram (rose-shaped arrangement) of the vertical cathode conductive drainage plate and the vertical anode conductive drainage plate array of the present invention. Figure 4 This is a top view schematic diagram of the vertical cathode conductive drainage plate and the vertical anode conductive drainage plate array arrangement of the present invention (parallel staggered arrangement). Figure 5 This is a top view schematic diagram (rose-shaped arrangement) of the vertical cathode conductive drainage plate and the vertical anode conductive drainage plate array of the present invention. In the diagram, 1 represents the water surface, 2 represents the mud surface, 3 represents the horizontal electric water-blocking system, 3-1 represents the horizontal cathode conductive drainage plate, 3-2 represents the horizontal anode conductive drainage plate, 4 represents the vertical electric water-blocking system, 4-1 represents the vertical water-blocking cathode plate, 4-2 represents the vertical water-blocking anode plate, 5 represents the cable, 6 represents the switch, 7-1 represents the first power source, 7-2 represents the second power source, 7-3 represents the third power source, 8 represents the electroosmosis-vacuum drainage system, 8-1 represents the vertical cathode conductive drainage plate, 8-2 represents the vertical anode conductive drainage plate, 9 represents the delivery pipe, 10 represents the valve, 11 represents the water vapor separation device, 12 represents the vacuum pump, 13 represents the electric water-blocking area, and 14 represents the electroosmosis-vacuum drainage area. Detailed Implementation

[0023] As shown in the figure, an underwater soft soil foundation treatment method combining electroosmosis and vacuum preloading is used to treat pore water in the drainage consolidation treatment area. The method uses an electroosmosis combined vacuum preloading system including an electric water-blocking system and an electroosmosis-vacuum drainage system. The electric water-blocking system is located above and beside the electroosmosis-vacuum drainage system. When the electroosmosis-vacuum drainage system drains water from the electroosmosis-vacuum drainage area, the pore water in the drainage consolidation treatment area moves from the anode to the cathode of the electroosmosis-vacuum drainage system under the action of an electric field and vacuum pressure and is discharged through a vacuum pump. The electric water-blocking system includes a horizontal water-blocking strip and a vertical water-blocking strip constructed with conductive drainage plates or metal electrodes. An electric potential gradient opposite to the hydraulic gradient around the drainage consolidation treatment area is formed between the cathode and anode to create isolation between the drainage consolidation treatment area and the surrounding water body, thus preventing backflow of water from the surrounding area when the electroosmosis-vacuum drainage system drains water.

[0024] The electric water-blocking system includes a horizontal electric water-blocking system 3 and a vertical electric water-blocking system 4 around the electroosmotic-vacuum drainage area. The horizontal electric water-blocking system consists of one or more horizontal cathode conductive drainage plates 3-1, one or more horizontal anode conductive drainage plates 3-2, cable 5, switch 6 and first power supply 7-1; the horizontal cathode conductive drainage plates and horizontal anode conductive drainage plates are placed on the surface of the soft soil foundation mud surface and connected to the first power supply, and the horizontal projections of the cathode and anode formed therein are staggered or perpendicularly intersecting. The vertical electric water-proof system consists of one or more vertical water-proof cathode plates 4-1, one or more vertical water-proof anode plates 4-2, cables 5, switches 6, and a second power supply 7-2; The vertical water-proof cathode plate and the vertical water-proof anode plate are vertically inserted into the deep part of the soft soil foundation; the vertical water-proof cathode plate is connected to the second power source through a cable and a switch; the vertical water-proof anode plate is connected to the second power source through a cable and a switch.

[0025] The vertical distance d1 between the horizontal cathode conductive drainage plate and the horizontal anode conductive drainage plate is between 0.5 and 1 m. The spacing d2 between each horizontal cathode conductive drainage plate and between each horizontal anode conductive drainage plate is between 0.4 and 0.6 m. The horizontal projection of the horizontal electric water-proof system completely covers the electroosmosis-vacuum drainage area 14 and the vertical electric water-proof system, and the extension distance d3 of the projection is at least 2m greater than the vertical water-proof cathode plate. The vertical distance d4 between the horizontal electric water-stop system and the vertical electric water-stop system is 0.2 to 0.5 m; Each vertical water-proof cathode plate is placed around the vertical water-proof anode plate, and the spacing between each vertical water-proof cathode plate is d6. The width d5 ​​of the vertical conductive drainage plate is approximately 0.1m. D1 = d5 + d6, and D1 is between 0.5 and 1m.

[0026] The electroosmosis-vacuum drainage system 8 consists of multiple vertical cathode conductive drainage plates 8-1, multiple vertical anode conductive drainage plates 8-2, cables 5, switches 6, a third power supply 7-3, a delivery pipe 9, valves 10, a water vapor separation device 11, and a vacuum pump 12. The vertical cathode conductive drainage plate and the vertical anode conductive drainage plate are vertically inserted into the deep soil of the electroosmosis-vacuum drainage area; the vertical cathode conductive drainage plate and the vertical anode conductive drainage plate are connected to the negative terminal and the anode of the third power source respectively through cables and switches; The vertical cathode conductive drainage plate is connected to the vacuum pump via a delivery pipe, valve, and water vapor separation device.

[0027] The distance d7 between the cathode and anode formed by the vertical cathode conductive drainage plate and the vertical anode conductive drainage plate is between 1 and 1.5 m; the distance from the bottom of the projection of the vertical cathode conductive drainage plate at the vertical water-proof anode plate to the bottom of the vertical water-proof anode plate is d8, and d8 is between 0.3 and 0.5 m.

[0028] The vertical cathode conductive drainage plate and the vertical anode conductive drainage plate are arranged in an array in the underwater soft soil area of ​​the electroosmosis-vacuum drainage zone. The outermost ring of the array is the cathode, and the inner ring is distributed in the order of "cathode-anode".

[0029] The top-view layout shape of the array includes a rose-shaped layout, a parallel staggered layout, or a rose-shaped layout.

[0030] The electrode materials of the electroosmotic-vacuum drainage system and the electric water-stop system are electric geosynthetic materials; in the electric water-stop system, the horizontal conductive drainage board is an electric drainage board, and the vertical conductive drainage board is an electric drainage board or an electric drainage pipe.

[0031] When using an electroosmosis combined with vacuum preloading system to treat underwater soft soil foundations, the energizing methods include continuous energizing, intermittent energizing, or staged energizing, and the vacuuming methods include continuous vacuuming, intermittent vacuuming, or staged vacuuming.

[0032] The method is an underwater soft soil foundation treatment method based on electroosmosis combined with vacuum preloading. The construction sequence during implementation includes the following steps. Step S1: First, install vertical cathode conductive drainage plates and vertical anode conductive drainage plates in the electroosmosis-vacuum drainage area; select the layout of the vertical conductive drainage plates according to specific circumstances. Step S2: Lay out the delivery pipe, arrange the water vapor separation device and arrange the vacuum pump to form the vacuum drainage system of the electroosmosis-vacuum drainage system, wherein the delivery pipe is connected to the vertical cathode conductive drainage plate; lay out the electroosmosis system including the cable and power supply of the electroosmosis-vacuum drainage system, wherein the vertical cathode conductive drainage plate and the vertical anode conductive drainage plate are respectively connected to the negative and positive terminals of the third power supply. Step S3: In the vertical electric water-proof system of the electric water-proof system, install a vertical water-proof cathode plate and a vertical water-proof anode plate, and connect the vertical water-proof cathode plate and the vertical water-proof anode plate to the negative and positive terminals of the second power supply respectively through cables. Step S4: In the horizontal electric water-stop system of the electric water-stop system, lay horizontal cathode conductive drainage boards and horizontal anode conductive drainage boards. Select the layout of the horizontal conductive drainage boards according to specific conditions, and connect the horizontal cathode conductive drainage boards and horizontal anode conductive drainage boards to the negative and positive terminals of the first power supply respectively through cables. Step S5: After the horizontal cathode conductive drainage board is laid, let it stand for a period of time to allow it to come into close contact with the soil.

[0033] Example 1: First, install vertical cathode conductive drainage plates 8-1 and vertical anode conductive drainage plates 8-2 in the electroosmosis-vacuum drainage area 14 (the arrangement of the vertical conductive drainage plates can be selected according to specific circumstances); install conveying pipes 9, cables 5, valves 10, water vapor separators 11, and vacuum pumps 12, connecting them to the vertical cathode conductive drainage plates 8-1 through the conveying pipes 9; install cables 5, switches 6, and power supplies 7-3, connecting the vertical cathode conductive drainage plates 8-1 to the negative terminal of power supplies 7-3, and simultaneously connecting the vertical anode conductive drainage plates 8-2 to the positive terminal of power supplies 7-3; then, in the vertical electric water-stopping system 4 of the electric water-stopping area, install vertical water-stopping cathodes... Electrode 4-1 and vertical water-proof anode plate 4-2 are connected; cable 5 is arranged, switch 6 and power supply 7-2 are installed, so that vertical water-proof cathode plate 4-1 is connected to the negative terminal of power supply 7-2, and vertical water-proof anode plate 4-2 is connected to the positive terminal of power supply 7-2; then in the horizontal electric water-proof system 3 of the electric water-proof area, horizontal cathode conductive drainage plate 3-1 and horizontal anode conductive drainage plate 3-2 are installed (the arrangement of the horizontal conductive drainage plate can be selected according to specific conditions); cable 5 is arranged, switch 6 and power supply 7-1 are installed, so that horizontal cathode conductive drainage plate 3-1 is connected to the negative terminal of power supply 7-1, and horizontal anode conductive drainage plate 3-2 is connected to the positive terminal of power supply 7-1.

[0034] in: The horizontal cathode conductive drainage plate 3-1 and the horizontal anode conductive drainage plate 3-2 are placed on the surface of the mud; the horizontal cathode conductive drainage plate 3-1 is 0.5m away from the surface of the underwater soft soil; the horizontal anode conductive drainage plate 3-2 is located below the horizontal cathode conductive drainage plate 3-1, and the horizontal projections of the anode and cathode are perpendicularly intersecting. The vertical distance d1 between the horizontal cathode conductive drainage plate 3-1 and the horizontal anode conductive drainage plate 3-2 is 1m; The spacing d2 between the horizontal cathode conductive drainage plates 3-1 and between the horizontal anode conductive drainage plates 3-2 is 0.6m; The horizontal projection of the horizontal electric water-proof system 3 completely covers the electroosmosis-vacuum drainage area 14 and the vertical electric water-proof system 4, and the extension distance is greater than the length d3 of the vertical water-proof cathode plate 4-1, which is 2m. The vertical distance d4 between the horizontal electric water-stop system 3 and the vertical electric water-stop system 4 is 0.5m; The vertical water-proof cathode plate 4-1 is placed around the vertical water-proof anode plate 4-2 with a spacing of d6, and the width d5 ​​of the vertical conductive drainage plate is 0.1m, D1=d5+d6, D1=1; The spacing of the vertical conductive drainage boards is d7, D2=d5+d7, D2=1.5; The distance from the bottom of the vertical cathode conductive drainage plate 8-1 projected onto the vertical water-proof anode plate 4-2 to the bottom of the vertical water-proof anode plate 4-2 is d8, and d8 is 0.5m. The vertical conductive drainage boards are arranged in a rose-shaped pattern (e.g., Figure 3 The above).

[0035] After setting up the device according to the above instructions, drainage can begin.

[0036] First, turn on switch 6 to power supply 7-2, and apply 10V to the vertical water-proof cathode plate 4-1 and vertical water-proof anode plate 4-2; simultaneously, power supply 7-1 should be turned on, and 10V should be applied to the horizontal cathode conductive drainage plate 3-1 and horizontal anode conductive drainage plate 3-2. Next, open valve 10 to power vacuum pump 12, applying a pressure of -20kPa to the soil. When drainage difficulties occur (drainage volume less than 200g in 16 hours), apply a pressure of -40kPa. When drainage difficulties recur, apply a pressure of -80kPa. Under this level of vacuum preloading, when soil drainage stabilizes, begin electroosmotic consolidation treatment. Then, turn on switch 6 to power supply 7-3, and apply 10V to the vertical cathode conductive drainage plate 8-1 and vertical anode conductive drainage plate 8-2 for 96 hours, followed by 8.0V for 48 hours, and then 9.5V. Continue to supply power until the soil settlement is relatively stable, then close switch 6 and valve 10 to stop power supply and vacuuming.

[0037] It should be noted that if the on-site construction conditions are not suitable for tiered power supply or tiered vacuuming, tiered power supply or vacuuming can be changed to the same gradient.

[0038] Finally, it should be noted that the above embodiments are only used to illustrate and explain the present invention, and are not intended to limit the present invention to the scope of these embodiments. Construction personnel can make selections and modifications according to specific actual conditions.

Claims

1. A method for treating underwater soft soil foundations using a combination of electroosmosis and vacuum preloading, for treating pore water in a drainage consolidation treatment area, characterized in that: The method utilizes an electroosmotic combined vacuum pre-compression system comprising an electric water-blocking system and an electroosmotic-vacuum drainage system. The electric water-blocking system is positioned above and beside the electroosmotic-vacuum drainage system. When the electroosmotic-vacuum drainage system drains water from the electroosmotic-vacuum drainage area, the pore water in the drainage consolidation treatment area moves from the anode to the cathode of the electroosmotic-vacuum drainage system under the action of an electric field and vacuum pressure, and is discharged through a vacuum pump. The electric water-blocking system includes a horizontal water-blocking strip and a vertical water-blocking strip constructed with conductive drainage plates or metal electrodes. An electric potential gradient opposite to the hydraulic gradient around the drainage consolidation treatment area is formed between the cathode and anode to create isolation between the drainage consolidation treatment area and the surrounding water body, thus preventing backflow of water from the surrounding area when the electroosmotic-vacuum drainage system drains water. The electric water-stop system includes a horizontal electric water-stop system (3) and a vertical electric water-stop system (4) around the electroosmotic-vacuum drainage area. The horizontal electric water-blocking system consists of one or more horizontal cathode conductive drainage plates (3-1), one or more horizontal anode conductive drainage plates (3-2), cables (5), switches (6) and a first power supply (7-1); the horizontal cathode conductive drainage plates and the horizontal anode conductive drainage plates are placed on the surface of the soft soil foundation mud surface and connected to the first power supply, and the horizontal projections of the cathode and anode formed therein are staggered or perpendicularly intersecting; The vertical electric water-proof system consists of one or more vertical water-proof cathode plates (4-1), one or more vertical water-proof anode plates (4-2), cables (5), switches (6) and a second power supply (7-2); The vertical water-proof cathode plate and the vertical water-proof anode plate are vertically inserted into the deep part of the soft soil foundation; the vertical water-proof cathode plate is connected to the second power source through a cable and a switch; the vertical water-proof anode plate is connected to the second power source through a cable and a switch.

2. The underwater soft soil foundation treatment method combining electroosmosis and vacuum preloading according to claim 1, characterized in that: The vertical distance d1 between the horizontal cathode conductive drainage plate and the horizontal anode conductive drainage plate is between 0.5 and 1 m. The spacing d2 between each horizontal cathode conductive drainage plate and between each horizontal anode conductive drainage plate is between 0.4 and 0.6 m. The horizontal projection of the horizontal electric water-proof system completely covers the electroosmotic-vacuum drainage area (14) and the vertical electric water-proof system, and the extension distance d3 of the projection is at least 2m greater than the vertical water-proof cathode plate. The vertical distance d4 between the horizontal electric water-stop system and the vertical electric water-stop system is 0.2 to 0.5 m; Each vertical water-proof cathode plate is placed outside the vertical water-proof anode plate, and the spacing between each vertical water-proof cathode plate is d6, and the width d5 ​​of the vertical conductive drainage plate is 0.1m, D1=d5+d6, and D1 is between 0.5 and 1m.

3. The underwater soft soil foundation treatment method combining electroosmosis and vacuum preloading according to claim 1, characterized in that: The electroosmosis-vacuum drainage system (8) consists of multiple vertical cathode conductive drainage plates (8-1), multiple vertical anode conductive drainage plates (8-2), cables (5), switches (6), a third power supply (7-3), a delivery pipe (9), valves (10), a water vapor separation device (11), and a vacuum pump (12). The vertical cathode conductive drainage plate and the vertical anode conductive drainage plate are vertically inserted into the deep soil of the electroosmosis-vacuum drainage area; the vertical cathode conductive drainage plate and the vertical anode conductive drainage plate are connected to the negative terminal and the anode of the third power source respectively through cables and switches; The vertical cathode conductive drainage plate is connected to the vacuum pump via a delivery pipe, valve, and water vapor separation device.

4. The underwater soft soil foundation treatment method combining electroosmosis and vacuum preloading according to claim 3, characterized in that: The distance d7 between the cathode and anode formed by the vertical cathode conductive drainage plate and the vertical anode conductive drainage plate is between 1 and 1.5 m; the distance from the bottom of the projection of the vertical cathode conductive drainage plate at the vertical water-proof anode plate to the bottom of the vertical water-proof anode plate is d8, and d8 is between 0.3 and 0.5 m.

5. The underwater soft soil foundation treatment method combining electroosmosis and vacuum preloading according to claim 3, characterized in that: The vertical cathode conductive drainage plate and the vertical anode conductive drainage plate are arranged in an array in the underwater soft soil area of ​​the electroosmosis-vacuum drainage zone. The outermost ring of the array is the cathode, and the inner ring is distributed in the order of "cathode-anode".

6. The underwater soft soil foundation treatment method combining electroosmosis and vacuum preloading according to claim 5, characterized in that: The top-view layout shape of the array includes a rose-shaped layout, a parallel staggered layout, or a rose-shaped layout.

7. The underwater soft soil foundation treatment method combining electroosmosis and vacuum preloading according to claim 3, characterized in that: The electrode materials of the electroosmotic-vacuum drainage system and the electric water-stop system are electric geosynthetic materials; in the electric water-stop system, the horizontal conductive drainage board is an electric drainage board, and the vertical conductive drainage board is an electric drainage board or an electric drainage pipe.

8. The underwater soft soil foundation treatment method combining electroosmosis and vacuum preloading according to claim 3, characterized in that: When using an electroosmosis combined with vacuum preloading system to treat underwater soft soil foundations, the energizing methods include continuous energizing, intermittent energizing, or staged energizing, and the vacuuming methods include continuous vacuuming, intermittent vacuuming, or staged vacuuming.

9. The underwater soft soil foundation treatment method combining electroosmosis and vacuum preloading according to claim 3, characterized in that: The method is an underwater soft soil foundation treatment method based on electroosmosis combined with vacuum preloading. The construction sequence during implementation includes the following steps. Step S1: First, install vertical cathode conductive drainage plates and vertical anode conductive drainage plates in the electroosmosis-vacuum drainage area; select the layout of the vertical conductive drainage plates according to specific circumstances. Step S2: Lay out the delivery pipe, arrange the water vapor separation device and arrange the vacuum pump to form the vacuum drainage system of the electroosmosis-vacuum drainage system, wherein the delivery pipe is connected to the vertical cathode conductive drainage plate; lay out the electroosmosis system including the cable and power supply of the electroosmosis-vacuum drainage system, wherein the vertical cathode conductive drainage plate and the vertical anode conductive drainage plate are respectively connected to the negative and positive terminals of the third power supply. Step S3: In the vertical electric water-proof system of the electric water-proof system, install a vertical water-proof cathode plate and a vertical water-proof anode plate, and connect the vertical water-proof cathode plate and the vertical water-proof anode plate to the negative and positive terminals of the second power supply respectively through cables. Step S4: In the horizontal electric water-stop system of the electric water-stop system, lay horizontal cathode conductive drainage boards and horizontal anode conductive drainage boards. Select the layout of the horizontal conductive drainage boards according to specific conditions, and connect the horizontal cathode conductive drainage boards and horizontal anode conductive drainage boards to the negative and positive terminals of the first power supply respectively through cables. Step S5: After the horizontal cathode conductive drainage board is laid, let it stand for a period of time to allow it to come into close contact with the soil.

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