Underwater vacuum preloading foundation treatment system and underwater foundation treatment method

Abstract

The present invention belongs to the technical field of underwater foundation treatment, and relates to an underwater vacuum preloading foundation treatment system and an underwater foundation treatment method. The system includes a medium-coarse sand cushion layer, a soft drain, a drainage board, a silt layer, and a vacuum device; the medium-coarse sand cushion layer covers the foundation to be treated, the drainage board passes through the medium-coarse sand cushion layer and is vertically inserted into the foundation to be treated, and the soft drain is laid on the medium-coarse sand cushion layer; the soft drain includes a soft woven bag, a plurality of drainage pipes inserted therein, and medium-coarse sand filled between the two; one end of the drainage pipe extends outward to be connected to the vacuum device; a plurality of water-permeable holes are opened on the wall of the drainage pipe located in the soft woven bag; and the silt layer covers the soft woven bag. The present invention can realize vacuum preloading of the underwater foundation to be treated by adopting a vertical drainage board and a horizontal soft drain for drainage and a silt layer for sealing, which can meet the needs of deep-water large-area soft foundation treatment and has strong operability.

Description

Technical Field

[0001] The present invention belongs to the technical field of underwater foundation treatment, and in particular relates to an underwater vacuum preloading foundation treatment system and an underwater foundation treatment method. Background Art

[0002] At present, vacuum preloading technology has developed to a relatively mature level, but underwater vacuum preloading technology has not been fully studied in theory and applied in large-scale construction, especially deep-water vacuum preloading technology is still in the research stage. Chinese invention patent CN113653024B discloses an underwater vacuum membrane laying method, which is suitable for soft foundation sites with shallow water depth and small treatment area, but is not suitable for deep sea waters and large-area soft foundation treatment. Chinese invention patent CN114000495B discloses an underwater vacuum preloading process. The laying of the sealing membrane is achieved by sinking the box tube to a predetermined depth. The sealing membrane is fixed on the tube skirt. The size of the foundation reinforcement area depends on the size of the box tube, which seriously restricts the development of the process and requires the dispatch of large professional offshore construction ships, which has high construction costs. Summary of the invention

[0003] In view of the deficiencies existing in the related art, the present invention provides an underwater vacuum preloading foundation treatment system and an underwater foundation treatment method.

[0004] The present invention provides an underwater vacuum preloading foundation treatment system, comprising a drainage system, a sealing system, and a vacuum pumping device; wherein:

[0005] The drainage system includes a medium-coarse sand cushion layer, a soft drainage bag, and a plurality of drainage boards; the medium-coarse sand cushion layer covers the underwater foundation to be treated; each drainage board passes through the medium-coarse sand cushion layer and is vertically inserted into the foundation to be treated; the soft drainage bag is laid on the medium-coarse sand cushion layer, and the soft drainage bag includes a soft woven bag and a plurality of drainage pipes; the soft woven bag has a plurality of parallel cylindrical main ribs; each drainage pipe is inserted into a main rib, and the outer wall of the drainage pipe and the inner wall of the main rib are filled with medium-coarse sand; one end of the drainage pipe is an external connection end, which extends out of the main rib and extends to the water surface; a plurality of water-permeable holes are opened on the wall of the drainage pipe located in the main rib, and the outer wall of the drainage pipe located in the main rib is also wrapped with an integrated water-permeable filter cloth;

[0006] The sealing system includes a sludge layer, which covers a soft woven bag;

[0007] The vacuum device is arranged above the water surface, and the external ends of all drainage pipes are connected to the vacuum device.

[0008] In some embodiments, the silt layer is made of silt with a permeability coefficient less than 1×10 -8 cm / s of clay, and mixed with 3% of the total weight of the silt with vegetable glue to make the silt paste-like.

[0009] In some of the embodiments, the outer boundary of the sludge layer uniformly expands outward by at least 5 m relative to the outer edge of the soft woven bag.

[0010] In some of the embodiments, the total area of ​​all the water-permeable holes on each drain pipe is 10% to 20% of the outer wall area of ​​the drain pipe located in the main rib channel.

[0011] In some embodiments, the distance between two adjacent main ribs is 1 m, and the inner diameter of the main rib is 10 cm to 15 cm.

[0012] In some of the embodiments, the soft woven bag further has a plurality of tubular secondary ribs connected between two adjacent primary ribs, and the secondary ribs are filled with medium-coarse sand.

[0013] In some of the embodiments, the vacuum pump includes a water-gas separation tank, a vacuum pump, a submersible pump and a water inlet pipe respectively connected to the water-gas separation tank; the water inlet pipe is provided with a plurality of connection ports, which are respectively connected to a plurality of external connection ends of drainage pipes of the soft drain; the water in the foundation to be treated can be sucked into the water-gas separation tank through the drainage system under the action of the vacuum pump, and water and gas separation is carried out in the water-gas separation tank, and the separated water is discharged to the outside of the water-gas separation tank through the submersible pump.

[0014] The present invention also provides an underwater foundation treatment method, which is performed using the underwater vacuum preloading foundation treatment system, and comprises the following steps:

[0015] S1. Laying a medium-coarse sand cushion layer on the underwater foundation to be treated;

[0016] S2. Install multiple drainage boards, pass through the medium-coarse sand cushion layer and vertically insert them into the foundation to be treated;

[0017] S3. Lay the soft drain on the medium-coarse sand cushion layer, and connect the external ends of all drain pipes to the vacuum device;

[0018] S4, blowing and filling the silt layer on the soft woven bags of the soft row;

[0019] S5. Start the vacuum pumping device to perform underwater vacuum preloading on the foundation to be treated until its consolidation degree reaches the preset requirements.

[0020] In some embodiments, in step S1, the laying thickness of the medium-coarse sand cushion layer is 1m to 2m; in step S4, the filling thickness of the silt layer is 1m to 2m.

[0021] In some of the embodiments, in step S2, a plurality of drain boards are arranged in a square, triangle or plum blossom shape, the spacing between any two adjacent drain boards is 0.8m to 1.2m, and the insertion depth of the drain boards in the foundation to be treated is equal to the thickness of the foundation to be treated.

[0022] Based on the above technical scheme, the underwater vacuum preloading foundation treatment system and the underwater foundation treatment method in the embodiments of the present invention adopt drainage plates for vertical drainage, soft drains with drainage pipes for horizontal drainage, and silt layers for sealing, which can realize vacuum preloading of underwater foundations to be treated, meet the needs of deep-water large-area soft foundation treatment, have strong operability, and can improve construction efficiency and reduce construction costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0024] Figure 1 It is a schematic diagram of the underwater vacuum preloading foundation treatment system of the present invention;

[0025] Figure 2 It is a partial cross-sectional view of the software row in the present invention;

[0026] Figure 3 It is a partial top view of the soft body row in the present invention;

[0027] Figure 4 It is a schematic diagram of positioning the drainage pipe at the end of the main rib channel in the present invention;

[0028] Figure 5 is a schematic diagram of a vacuum pumping device in the present invention;

[0029] Figure 6 The figure is a flow chart of the underwater foundation treatment method of the present invention.

[0030] In the figure:

[0031] 1. Soft drain; 11. Soft woven bag; 111. Main rib; 112. Secondary rib; 12. Drain pipe; 13. Medium-coarse sand; 14. Ring; 2. Drain board; 3. Medium-coarse sand cushion; 4. Silt layer; 5. Vacuum device; 51. Water-gas separation tank; 52. Vacuum pump; 53. Submersible pump; 54. Water inlet pipe; 541. Connecting port. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0033] In the description of the present invention, it should be understood that the terms "center", "lateral", "longitudinal", "up", "down", "top", "bottom", "inside", "outside", "left", "right", "front", "back", "vertical", "horizontal", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0034] The terms "first", "second", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first", "second", etc. may explicitly or implicitly include one or more of the features.

[0035] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0036] refer to Figure 1-Figure 6 As shown, the present invention provides an underwater vacuum preloading foundation treatment system, which is intended to perform foundation reinforcement treatment on underwater soft foundation. The underwater vacuum preloading foundation treatment system includes a drainage system, a sealing system, and a vacuum device 5. The drainage system includes a medium-coarse sand cushion layer 3, a soft drainage 1, and a plurality of drainage boards 2.

[0037] The medium-coarse sand cushion layer 3 covers the underwater foundation to be treated, that is, covers the area to be reinforced of the foundation to be treated; the medium-coarse sand cushion layer 3 has a certain thickness, forming a preliminary horizontal drainage cushion layer. Each drain board 2 passes through the medium-coarse sand cushion layer 3 and is vertically inserted into the foundation to be treated, and multiple drain boards 2 are arranged according to a preset rule; specifically, the top of the drain board 2 is located within the medium-coarse sand cushion layer 3, and most of the drain boards 2 are located in the foundation to be treated. The water in the foundation to be treated can flow upward along the multiple drain boards 2 under the action of the external vacuum pre-pressure suction, and then enter the medium-coarse sand cushion layer 3.

[0038] The soft drainage 1 is laid on the medium-coarse sand cushion 3, that is, the soft drainage 1 is laid horizontally as a whole. The soft drainage 1 includes a soft woven bag 11 and a plurality of horizontally arranged drainage pipes 12; the drainage pipes 12 are hard plastic pipes. The soft woven bag 11 has a plurality of horizontally arranged and mutually parallel cylindrical main ribs 111, and the main ribs 111 extend longitudinally or transversely to the end side of the soft woven bag 11; it can be understood that the soft woven bag 11 is a water-permeable geotextile made of synthetic fibers by needle punching or weaving, which has the advantages of high strength and good water permeability; the top of the drainage board 2 can be directly attached to the soft woven bag 11. The rib cavity space of the main rib channel 111 is larger than the outer diameter of the drain pipe 12; each drain pipe 12 is inserted into a main rib channel 111 along the length direction of the main rib channel 111, and the outer wall of the drain pipe 12 and the inner wall of the main rib channel 111 are filled with medium-coarse sand 13, so that the main rib channel 111 on the soft body row 1 is cylindrical or approximately cylindrical; further, a sleeve ring 14 is respectively arranged at both ends of the length direction of the main rib channel 111, the outer wall size of the sleeve ring 14 is adapted to the inner wall of the main rib channel 111, the inner hole size of the sleeve ring 14 is adapted to the outer diameter of the drain pipe 12, and the drain pipe 12 is inserted into the inner hole of the sleeve ring 14, so that the drain pipe 12 and the main rib channel 111 are coaxially arranged; the sleeve ring 14 has a plurality of hollow holes, and the medium-coarse sand 13 can be filled between the drain pipe 12 and the main rib channel 111 through the hollow holes. One end of the drain pipe 12 is an external connection end, which extends out of the main rib channel 111 and toward the water surface. A plurality of water-permeable holes (not shown) are provided on the wall of the drain pipe 12 located in the main rib channel 111, and the plurality of water-permeable holes are evenly arranged along the length direction and circumference direction of the drain pipe 12; the water in the foundation to be treated enters the medium-coarse sand cushion layer 3 through the drain board 2 under the action of the external vacuum pre-pressure suction, and then enters the drain pipe 12 through the soft woven bag 11, the medium-coarse sand 13 outside the drain pipe 12, and the water-permeable holes on the wall of the drain pipe 12 in sequence. No holes are provided on the wall of the drain pipe 12 located outside the main rib channel 111 to prevent water in the water area from directly entering the drain pipe 12. Furthermore, the outer wall of the drain pipe 12 located in the main rib channel 111 is also wrapped with an integrated water-permeable filter cloth, which has the function of being water-permeable but not sand-permeable, to prevent small sand particles from entering the drain pipe 12 through the water-permeable holes.

[0039] The sealing system includes a silt layer 4, which covers the soft woven bag 11, so that the entire top surface of the soft woven bag 11 including the main ribs 111 is completely covered by the silt layer 4. The silt layer 4 has a certain thickness and a low permeability coefficient, which can isolate and seal the soft woven bag 11 from the water in the water area above it, and prevent the water in the water area from directly entering the soft drain 1.

[0040] The vacuum device 5 is arranged above the water surface, and the external ends of all the drainage pipes 12 in the soft drain 1 are connected to the vacuum device 5; when the vacuum device 5 is working, the vacuum pressure is transmitted to the underwater through the soft drain 1 with the drainage pipe 12, so that a negative pressure environment is formed under the silt layer 4. Under the action of negative pressure, the water in the foundation to be treated is first vertically drained through the drainage board 2, and then horizontally drained through the soft drain 1 with the drainage pipe 12, and then discharged from the drainage pipe 12, thereby realizing underwater vacuum preloading of the foundation to be treated, so that the effective stress of the foundation to be treated is continuously increased, and the foundation to be treated is gradually consolidated, thereby realizing the reinforcement treatment of the underwater foundation to be treated.

[0041] The above-mentioned schematic embodiment, by adopting a vertical drainage board 2 and a horizontal soft drain 1 with a drainage pipe 12 as a drainage system and a silt layer 4 as a sealing system, can achieve vacuum preloading of the underwater foundation to be treated, so that the reinforcement treatment of the foundation to be treated is not limited by the water depth and the foundation reinforcement area, thereby being able to meet the needs of deep-water large-area soft foundation treatment and having strong operability.

[0042] In some embodiments, the silt layer 4 is made of silt with a permeability coefficient less than 1×10 -8 cm / s clay, and mixed with 3% of the total weight of the silt, so that the silt is paste-like; thereby ensuring that the silt layer 4 has good sealing performance and ensuring that the entire underwater vacuum preloading foundation treatment system can form a complete and reliable vacuum system, thereby realizing true underwater vacuum preloading.

[0043] refer to Figure 1 As shown, in some embodiments, the outer boundary of the silt layer 4 is uniformly expanded outward by at least 5m relative to the outer edge of the soft woven bag 11. The external end of the drain pipe 12 in the soft drain 1 can pass through the silt layer 4, and the sealing of the drain pipe 12 at the point where it passes through the silt layer 4 must be ensured. This exemplary embodiment reliably prevents water in the water area from entering the soft drain 1 by setting the silt layer 4 outward relative to the soft woven bag 11.

[0044] In some embodiments, the total area of ​​all water-permeable holes on each drainage pipe 12 is 10% to 20% of the outer wall area of ​​the drainage pipe 12 located in the main rib channel 111 to ensure the drainage effect when the treated foundation is vacuum preloaded.

[0045] refer to Figure 2-Figure 3 As shown, in some embodiments, the distance between two adjacent main ribs 111 is 1 m, and the inner diameter of the main rib 111 is 10 cm to 15 cm; the outer diameter of the drainage pipe 12 is smaller than the inner diameter of the main rib 111 .

[0046] refer to Figure 3As shown, in some embodiments, the soft woven bag 11 also has a plurality of cylindrical secondary ribs 112 connected between two adjacent primary ribs 111, and the secondary ribs 112 are filled with medium-coarse sand 13; the secondary ribs 112 can be arranged vertically with the primary ribs 111. This exemplary embodiment assists the flow of water in the soft drain 1 by arranging the secondary ribs 112 between the primary ribs 111. In case of poor flow or blockage in a particular drain pipe 12, water can quickly flow into other drain pipes 12 through the secondary ribs 112 filled with medium-coarse sand 13, thereby ensuring the overall drainage effect of the soft drain 1 with the drain pipe 12.

[0047] refer to Figure 5 As shown, in some embodiments, the vacuum device 5 includes a water-gas separation tank 51, a vacuum pump 52, a submersible pump 53 and a water inlet pipe 54 respectively connected to the water-gas separation tank 51. Usually, a water inlet and an air suction port are provided at the upper part of the water-gas separation tank 51, and a drain port is provided at the lower part of the water-gas separation tank 51; the vacuum pump 52 is connected to the air suction port, the submersible pump 53 is connected to the drain port, and the water inlet pipe 54 is connected to the water inlet. A plurality of connection ports 541 are provided on the water inlet pipe 54, and the plurality of connection ports 541 are respectively connected to the external connection ends of the plurality of drain pipes 12 of the soft drain 1. The water in the foundation to be treated can be sucked into the water-gas separation tank 51 through the drainage system and the water inlet pipe 54 under the action of the vacuum pump 52, and water and gas are separated in the water-gas separation tank 51, the separated gas is pumped out of the tank by the vacuum pump 52, and the separated water is discharged to the outside of the water-gas separation tank 51 through the submersible pump 53, and can be directly discharged into the water.

[0048] refer to Figure 1-Figure 6 As shown, the present invention also provides an underwater foundation treatment method, which is performed using the aforementioned underwater vacuum preloading foundation treatment system, and includes the following steps:

[0049] S1. Laying a medium-coarse sand cushion layer 3 on the underwater foundation to be treated, and making the top surface of the medium-coarse sand cushion layer 3 horizontal, so as to form a preliminary horizontal drainage cushion layer;

[0050] S2. Use a professional installation ship to install multiple drainage boards 2, so that each drainage board 2 passes through the medium-coarse sand cushion layer 3 and is vertically inserted into the foundation to be treated;

[0051] S3, using a professional laying boat to lay the soft drainage 1 on the medium-coarse sand cushion 3, and connect the external ends of all drainage pipes 12 to the vacuum device 5;

[0052] S4. Use a professional underwater mud blowing pipeline to blow the silt layer 4 on the soft woven bag 11 of the soft row 1; it is understandable that before blowing the silt layer 4, a thin layer of medium-coarse sand cushion layer 3 can be laid on the soft woven bag 11 to fill the height difference between the top of the main rib 111 and the plane of the soft woven bag 11, which is convenient for blowing the silt layer 4 and is also conducive to ensuring the isolation and sealing effect of the silt layer 4 on the soft woven bag 11;

[0053] S5. Start the vacuum pump 5 to perform vacuum preloading on the treated foundation until the consolidation degree of the treated foundation reaches the preset requirement; specifically, start the vacuum pump 52 to perform vacuum extraction so that the water in the treated foundation enters the water-gas separation tank 51 through the drainage system; start the submersible pump 53 to discharge the water separated in the water-gas separation tank 51 out of the tank; it is understandable that during the vacuum extraction process, it is necessary to check whether the silt layer 4 is cracked or leaking. If so, it should be repaired in time to avoid affecting the vacuum preloading effect of the treated foundation due to leakage.

[0054] The above-mentioned schematic embodiment improves the drainage efficiency of the underwater foundation to be treated during vacuum preloading by adopting a vertical drainage board 2 and a soft drain 1 with a drainage pipe 12 for combined drainage; and ensures that a reliable negative pressure environment is formed under the silt layer 4 by sealing; thus, the reinforcement treatment of the foundation to be treated is not limited by the water depth and the foundation reinforcement area, and can meet the needs of deep-water large-area soft foundation treatment, with strong operability and easy implementation; moreover, compared with the prior art, the entire underwater foundation treatment method of this embodiment has a lower construction difficulty, and can directly carry out large-area soft foundation treatment underwater, which can improve construction efficiency and reduce construction costs.

[0055] refer to Figure 1 As shown, in some embodiments, in step S1, the laying thickness of the medium-coarse sand cushion layer 3 is 1m~2m, ensuring that the medium-coarse sand cushion layer 3 can provide stable support for the soft row 1; in step S4, the filling thickness of the silt layer 4 is 1m~2m, ensuring the sealing performance of the silt layer 4, and avoiding the silt layer 4 from cracking and leaking during vacuum preloading of the foundation to be treated.

[0056] refer to Figure 1 As shown, in some embodiments, in step S2, multiple drain boards 2 are arranged in a square, triangular or plum blossom-shaped array, the spacing between two adjacent drain boards 2 is 0.8m to 1.2m, and the insertion depth of the drain boards 2 in the foundation to be treated is equal to the thickness of the foundation to be treated; thereby ensuring that the water in the foundation to be treated can be fully drained through the drain boards 2.

[0057] In summary, the underwater vacuum preloading foundation treatment system and underwater foundation treatment method of the present invention adopt a drainage board 2 for vertical drainage, a soft drain 1 with a drainage pipe 12 for horizontal drainage, and a silt layer 4 for sealing, which can realize vacuum preloading of the underwater foundation to be treated, can meet the needs of deep-water large-area soft foundation treatment, has strong operability, and can improve construction efficiency and reduce construction costs.

[0058] Finally, it should be noted that: the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0059] The above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or some technical features can be replaced by equivalents without departing from the spirit of the technical solution of the present invention, which should be included in the scope of the technical solution for protection of the present invention.

Claims

1. An underwater vacuum preloading foundation treatment system, characterized in that: It includes drainage system, sealing system and vacuum device; among which, The drainage system includes a medium-coarse sand cushion layer, a soft drainage system, and a plurality of drainage boards; the medium-coarse sand cushion layer covers the underwater foundation to be treated, and the laying thickness of the medium-coarse sand cushion layer is 1m to 2m; each of the drainage boards passes through the medium-coarse sand cushion layer and is vertically inserted into the foundation to be treated; the soft drainage system is laid on the medium-coarse sand cushion layer, and the soft drainage system includes a soft woven bag and a plurality of drainage pipes; the soft woven bag has a plurality of parallel cylindrical main ribs; each of the drainage pipes is inserted into a main rib The rib channel is formed in the drain pipe, and the outer wall of the drain pipe and the inner wall of the main rib channel are filled with medium-coarse sand; one end of the drain pipe is an external end, and the external end extends out of the main rib channel and extends to the water surface; a plurality of water-permeable holes are opened on the wall of the drain pipe located in the main rib channel, and an integrated water-permeable filter cloth is also wrapped on the outer wall of the drain pipe located in the main rib channel; the soft woven bag also has a plurality of cylindrical secondary rib channels connected between two adjacent main rib channels, and the secondary rib channels are filled with medium-coarse sand; The sealing system comprises a silt layer, which is covered on a soft woven bag. The silt used in the silt layer has a permeability coefficient of less than 1×10 -8 cm / s clay, and mixed with 3% of the total weight of the silt, so that the silt is paste-like; the filling thickness of the silt layer is 1m to 2m; The vacuum pumping device is arranged above the water surface, and the external ends of all the drainage pipes are connected to the vacuum pumping device.

2. The underwater vacuum preloading foundation treatment system according to claim 1, characterized in that: The outer boundary of the sludge layer is uniformly expanded outward by at least 5m relative to the outer edge of the soft woven bag.

3. The underwater vacuum preloading foundation treatment system according to claim 1, characterized in that: The total area of ​​all the water-permeable holes on each of the drainage pipes is 10% to 20% of the outer wall area of ​​the drainage pipe located in the main rib channel.

4. The underwater vacuum preloading foundation treatment system according to claim 1, characterized in that: The distance between two adjacent main ribs is 1 m, and the inner diameter of the main rib is 10 cm to 15 cm.

5. The underwater vacuum preloading foundation treatment system according to claim 1, characterized in that: The vacuum pumping device includes a water-gas separation tank, a vacuum pump, a submersible pump and a water inlet pipe respectively connected to the water-gas separation tank; the water inlet pipe is provided with a plurality of connecting ports, which are respectively connected to the external connection ends of a plurality of drainage pipes of the soft drain; the water in the foundation to be treated can be sucked into the water-gas separation tank through the drainage system under the action of the vacuum pump, and water and gas separation is carried out in the water-gas separation tank, and the separated water is discharged to the outside of the water-gas separation tank through the submersible pump.

6. An underwater foundation treatment method, characterized in that: The underwater vacuum preloading foundation treatment system according to any one of claims 1 to 5 is used, comprising the following steps: S1. laying the medium-coarse sand cushion layer on the underwater foundation to be treated; S2, installing a plurality of the drainage boards, passing through the medium-coarse sand cushion layer and vertically inserted into the foundation to be treated; S3, laying the soft drain on the medium-coarse sand cushion layer, and connecting the external ends of all the drain pipes to the vacuum device; S4, blowing and filling the silt layer on the soft woven bags of the soft row; S5. Start the vacuum pumping device to perform underwater vacuum preloading on the foundation to be treated until its consolidation degree reaches a preset requirement.

7. The underwater foundation treatment method according to claim 6, characterized in that: In step S2, the plurality of drain boards are arranged in a square, triangle or plum blossom shape, the spacing between two adjacent drain boards is 0.8m to 1.2m, and the insertion depth of the drain boards in the treated foundation is equal to the thickness of the treated foundation.

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