Soft soil deep foundation pit supporting structure for building construction and supporting construction method thereof

Abstract

The application relates to the field of foundation pit supporting structures, in particular to a soft soil deep foundation pit supporting structure for building construction and a supporting construction method thereof, which comprises a connecting plate, a fixed outer pipe, a fixed inner pipe, an oblique insertion plate and a ramming block. The fixed outer pipe is inserted into a soil body, the application effectively solves the problems that the soft soil deep foundation pit supporting structure is easy to incline, loosen and even collapse in the background technology, the fixed outer pipe is used as a main bearing framework, and the oblique insertion plate is obliquely inserted into the deep soil body from the bottom of the fixed outer pipe to form an anti-sliding anchoring system, the anti-overturning capacity is obviously improved, the connecting plate is rigidly connected with the fixed outer pipe through T-shaped reinforcing ribs, the ramming block is arranged in the gap formed on the two sides of the uplift of the connecting plate and the ground surface, the ground surface can be pre-rammed before installation, the compactness of the shallow soil body is improved, root instability is prevented, the overall structure is suitable for soft soil, large and deep foundation pits, and the supporting stability and construction safety are greatly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of foundation pit support structure, in particular to a soft soil deep foundation pit support structure for building construction and a support construction method thereof. BACKGROUND

[0002] The conventional deep foundation pit support structure suitable for hard soil is generally inserted into the ground along the edge of the foundation pit by a pile machine with the support plates one by one. This support structure is relatively simple, and the end inserted into the ground can be fixed in the soil. However, for soft soil, the end inserted into the ground will tilt with the movement of the soil, thereby losing the support effect. For a small foundation pit, support rods are arranged inside to support the upper end of the support plate. However, for a large and deep foundation pit, the spacing between the two support plates is tens of meters, and it is not practical to support the upper end of the support plate with support rods. If one end of the support rod is inserted into the ground to form a diagonal bracing structure to support the upper end of the support plate, the support rod will also loosen with the movement of the underground soil, thereby losing the support effect. SUMMARY

[0003] The present application provides a soft soil deep foundation pit support structure for building construction and a support construction method thereof, which overcomes the deficiencies described in the background art.

[0004] The technical solution adopted by the present application to solve its technical problems is as follows:

[0005] A soft soil deep foundation pit support structure for building construction, comprising a connecting plate, a fixed outer pipe, a fixed inner pipe, an inclined insertion plate, and a rammed block, the fixed outer pipe is inserted into the soil, the connecting plate is fixed to the upper part of the fixed outer pipe through a T-shaped reinforcing rib, and the bottom of the connecting plate abuts against the surface of the soil, the fixed inner pipe is arranged on the inner side of the lower part of the fixed outer pipe, and the lower end of the fixed inner pipe abuts against the surface of the soil, the left and right sides of the connecting plate are upwardly convex, and there is a spacing between the left and right sides of the connecting plate and the surface of the soil, the rammed block is arranged in the spacing, the inclined insertion plate is arranged on the lower side of the fixed outer pipe, and the inclined insertion plate is inserted into the soil after being inclined and penetrating through the fixed inner pipe and the fixed outer pipe in sequence.

[0006] The connecting plate further comprises a rectangular expansion insertion plate and a spiral expansion pipe, the rectangular expansion insertion plates are symmetrically arranged on the left and right sides of the connecting plate, all the rectangular expansion insertion plates extend through the connecting plate and into the soil, and a spiral expansion pipe is arranged between every two opposite rectangular expansion insertion plates, and the two ends of the spiral expansion pipe abut against the corresponding rectangular expansion insertion plates on the two sides.

[0007] In a preferred technical solution, an included angle is formed between the two adjacent rammed blocks, and a plurality of connecting rods are fixed between the two adjacent rammed blocks.

[0008] A preferred technical solution, the surface of the ramming block is provided with a bolt, the bolt penetrates through the connecting plate, and the bolt is provided with a gasket and a nut, the gasket and the nut are arranged on the surface of the part of the bolt penetrating through the connecting plate, and the nut is arranged above the gasket, the nut and the bolt are threadedly connected, when the nut is turned clockwise, the gasket is adjusted to press the connecting plate downward.

[0009] A preferred technical solution, it also includes a communication pipe one penetrating through the connecting plate and the ramming block, one end of the communication pipe one is communicated with the concrete pouring device, and the other end penetrates through the connecting plate and the ramming block in sequence and extends above the inclined insertion plate, when the concrete pouring device pours concrete through the communication pipe one, the concrete is transported to the surface of the inclined insertion plate through the communication pipe one, and a pouring layer is formed outside the inclined insertion plate.

[0010] A preferred technical solution, the rectangular telescopic insertion plate is sequentially sleeved with a square outer tube, a square inner tube and a connecting insertion plate from outside to inside, the spiral telescopic pipe includes an outer spiral pipe and a threaded inner pipe, the threaded inner pipe is symmetrically arranged on the left and right sides of the outer spiral pipe, and the threaded inner pipes on the two sides are respectively threadedly connected with the outer spiral pipe, and the ends of the two threaded inner pipes away from the outer spiral pipe are connected with the adjacent connecting insertion plates;

[0011] The surface of the connecting insertion plate is provided with a through hole penetrating to the upper and lower ends, the communication pipe one extends above the inclined insertion plate after penetrating through the through hole;

[0012] The surface of the fixed outer tube near the spiral telescopic pipe is provided with an extension retaining plate, the extension retaining plate is symmetrically arranged on the upper and lower ends of the spiral telescopic pipe, and the extension retaining plate extends towards the middle part of the fixed outer tube.

[0013] A preferred technical solution, the lower part of the fixed inner tube is provided with an outwardly protruding negative pressure placing part, the inner side of the negative pressure placing part is provided with a negative pressure assembly, the negative pressure assembly includes a mounting plate, an air compressor and a communication pipe two, the mounting plate is connected with the negative pressure placing part through a sealing ring arranged on the lower end of the mounting plate to form a piston connection, a cavity is formed between the mounting plate and the negative pressure placing part, the air compressor is arranged on the upper end of the mounting plate, and the air compressor creates negative pressure in the cavity through an air outlet arranged in the cavity;

[0014] One end of the communication pipe two is connected with a water pump, and the other end penetrates through the mounting plate and extends to the bottom of the negative pressure placing part;

[0015] The lower end of the negative pressure placing part is provided with a permeable membrane layer on both sides, the side of the permeable membrane layer close to the air compressor is provided with a movable closure, the movable closure abuts against the surface of the permeable membrane layer, and the movable closure includes a cover plate, a positioning column and a spring, the positioning column is arranged on the left and right sides of the adjacent permeable membrane layer respectively and penetrates through the cover plate, and the spring is symmetrically arranged on the two sides of the cover plate close to the positioning column.

[0016] The application discloses a construction method of a soft soil deep foundation pit supporting structure for building construction.

[0017] The connecting pipe is connected with the concrete pouring device, and after penetrating through the connecting plate, the ramming block and the square-shaped telescopic plug plate on the side surface of the fixed outer pipe, the connecting pipe extends to above the inclined plug plate, the concrete pouring device is used to transmit the concrete to the soil body through the inclined plug plate, and a pouring layer is formed.

[0018] Compared with the prior art, the technical scheme has the following advantages.

[0019] The application effectively solves the problems of the soft soil deep foundation pit supporting structure in the background art, such as easy inclination, loosening and even collapse, the fixed outer pipe is used as a main bearing framework, and the inclined plug plate is inclinedly penetrated into the deep soil body from the bottom of the fixed outer pipe to form an anti-sliding anchoring system, and the anti-overturning capacity is significantly improved; the connecting plate is rigidly connected with the fixed outer pipe through the T-shaped reinforcing rib, the ramming block is arranged in the gap formed on the two sides of the raised portion of the connecting plate and the ground surface, the ground surface can be pre-rammed before installation, the compactness of the shallow soil body is enhanced, the root instability is prevented, and the overall structure is suitable for the soft soil, large and deep foundation pit, and the supporting stability and construction safety are greatly improved. BRIEF DESCRIPTION OF DRAWINGS

[0020] The application will be further described below in combination with the drawings and examples.

[0021] Figure 1 It is a whole diagram of the application.

[0022] Figure 2 It is a structure schematic diagram of the square-shaped telescopic plug plate and the spiral telescopic pipe.

[0023] Figure 3 It is Figure 2 It is an enlarged schematic diagram of b in the figure.

[0024] Figure 4 It is Figure 2 It is an enlarged schematic diagram of a in the figure.

[0025] Figure 5 It is Figure 1 It is a top view schematic diagram.

[0026] Figure 6 It is a structure schematic diagram of the square-shaped telescopic plug plate and the spiral telescopic pipe.

[0027] Figure 7 It is a schematic diagram of the extension retaining plate.

[0028] Figure 8 Structure diagram of negative pressure placement piece and negative pressure assembly.

[0029] Figure 9 Structure diagram of negative pressure placement piece.

[0030] In the figure: connecting plate 1, fixed outer tube 2, fixed inner tube 3, inclined insertion plate 4, ramming block 5, rectangular telescopic insertion plate 6, spiral telescopic tube 7, communication tube 8, pouring layer 100;

[0031] T-shaped reinforcing rib 11;

[0032] Extended retaining plate 21;

[0033] Negative pressure placement piece 31, permeable membrane layer 311, movable closure 312, cover plate 3121, positioning column 3122, spring 3123, negative pressure assembly 32, mounting plate 321, sealing ring 3211, air compressor 322, air outlet 3221;

[0034] Bolt 51, gasket 52, nut 53, connecting rod 54;

[0035] Square outer tube 61, square inner tube 62, adapter insertion plate 63, through hole 631;

[0036] Outer spiral tube 71, threaded inner tube 72. DETAILED DESCRIPTION

[0037] As Figures 1 to 9 shown, the application proposes a soft soil deep foundation pit support structure for building construction, which comprises connecting plate 1, fixed outer tube 2, fixed inner tube 3, inclined insertion plate 4 and ramming block 5. The fixed outer tube 2 is inserted into the soil body, the connecting plate 1 is fixed to the upper part of the fixed outer tube 2 through a T-shaped reinforcing rib 11, and the bottom of the connecting plate 1 abuts against the surface of the soil body. The fixed inner tube 3 is arranged on the inner side of the lower part of the fixed outer tube 2, and the lower end of the fixed inner tube 3 abuts against the surface of the soil body. The left and right sides of the connecting plate 1 are upwardly convex, and there is a gap between the left and right sides of the connecting plate 1 and the surface of the soil body. The ramming block 5 is arranged in the gap. The inclined insertion plate 4 is arranged on the lower side of the fixed outer tube 2, and the inclined insertion plate 4 is inserted into the soil body after being inclined and penetrating through the fixed inner tube 3 and the fixed outer tube 2 in turn.

[0038] The connecting plate 1 is also provided with a rectangular telescopic insertion plate 6 and a spiral telescopic tube 7. The rectangular telescopic insertion plates 6 are symmetrically arranged on the left and right sides of the connecting plate 1, and all the rectangular telescopic insertion plates 6 extend through the connecting plate 1 and into the soil body. There is a spiral telescopic tube 7 between every two opposite rectangular telescopic insertion plates 6, and the two ends of the spiral telescopic tube 7 abut against the corresponding rectangular telescopic insertion plates 6 on the two sides.

[0039] During construction, the fixed outer tube 2 is first vertically pressed into soft soil to the designed depth as the main bearing framework; then the fixed inner tube 3 is placed in the fixed outer tube 2 at the lower part, with the lower end only reaching the ground surface, mainly providing guidance and passage for the inclined plate 4 and enhancing the local pipe wall stiffness. The inclined plate 4 penetrates from the bottom of the fixed outer tube 2 to the deep stable soil layer in an inclined manner, forming a structure similar to a micro anti-slide pile, effectively resisting the overturning moment generated by soil pressure and preventing the overall tilting of the support system.

[0040] The connecting plate 1 is rigidly connected to the top of the fixed outer tube 2 through the T-shaped reinforcing rib 11, with the bottom surface tightly adhering to the ground surface to limit the displacement of the top of the support structure; at the same time, the left and right sides of the connecting plate 1 are upwardly raised, forming a gap between the connecting plate 1 and the ground surface, and the gap is filled with the rammed block 5 to locally compact the disturbed surface layer soil and suppress the root loosening caused by the flow of shallow soil. In particular, the rammed block 5 can be pressed or rammed into the ground surface before the installation of the support structure to pre-reinforce the shallow soft soil, significantly improving the surface bearing capacity and compactness.

[0041] Furthermore, an included angle is formed between the left and right adjacent rammed blocks 5, and a plurality of connecting rods 54 are fixed between the two adjacent rammed blocks 5.

[0042] Further, the rammed block 5 is provided with a bolt 51 penetrating through the connecting plate 1, and a gasket 52 and a nut 53 are provided on the surface of the bolt 51 penetrating through the connecting plate 1, and the nut 53 is arranged above the gasket 52, and the nut 53 is threadedly connected with the bolt 51, and when the nut 53 is rotated clockwise, the gasket 52 is adjusted to press the connecting plate 1 downward.

[0043] As can be seen from the above, in the present application, the bolt 51 vertically penetrates through the raised side of the connecting plate 1, and the end of the bolt 51 penetrating out of the upper surface of the connecting plate 1 is sequentially sleeved with the gasket 52 and the nut 53, wherein the gasket 52 is attached to the upper surface of the connecting plate 1 to increase the stress area and prevent local crushing; the nut 53 is threadedly connected with the exposed threaded segment of the bolt 51 and is located above the gasket 52; after the support structure is initially installed, if a small gap exists between the bottom of the connecting plate 1 and the ground surface, or the compactness of the shallow soft soil is insufficient due to disturbance, an operator can use a wrench or the like to rotate the nut 53 clockwise. As the nut 53 is rotated downward along the bolt 51, the bottom surface of the nut 53 gradually presses the gasket 52, thereby applying a controllable, vertically downward pre-tightening force to the connecting plate 1. This force is transmitted to the soil surface contacted by the bottom of the connecting plate 1 through the connecting plate 1, and simultaneously acts in the opposite direction on the rammed block 5 below, forcing the rammed block 5 to further embed or compact the soft soil layer below.

[0044] Further, the supporting structure further comprises a first communication pipe 8 penetrating through the connecting plate 1 and the ramming block 5, one end of the first communication pipe 8 is communicated with the concrete pouring device, and the other end penetrates through the connecting plate 1 and the ramming block 5 in turn and extends above the inclined plate 4, when the concrete pouring device pours concrete through the first communication pipe 8, the concrete is transported to the surface of the inclined plate 4 through the first communication pipe 8, and a pouring layer 100 is formed outside the inclined plate 4;

[0045] The arrangement of the first communication pipe 8 enables the concrete to be accurately injected from the ground surface to the area above the inclined plate 4, avoiding the spread of the slurry out of control or loss in the soft soil, and ensuring that the reinforcement position is controllable; after the pouring layer 100 formed in this way is solidified outside the inclined plate 4, not only the bonding strength and integrity with the surrounding soil are significantly improved, but also the supporting mechanism originally relying on passive earth pressure is converted into an active anchoring system, effectively inhibiting the displacement accumulation caused by the soft soil creep, and enhancing the anti-deformation ability of the structure under long-term load, thereby greatly improving the stability and reliability of the entire supporting system, and after the concrete is poured, the first communication pipe does not need to be removed, so that the first communication pipe and the solidified concrete simultaneously fix the supporting structure.

[0046] Further, the rectangular telescopic plate 6 is sequentially sleeved with a square outer pipe 61, a square inner pipe 62 and a connecting plate 63 from outside to inside, the screw telescopic pipe 7 comprises an outer screw pipe 71 and a threaded inner pipe 72, the threaded inner pipe 72 is symmetrically arranged on the left and right sides of the outer screw pipe 71, and the threaded inner pipes 72 on the two sides are respectively in threaded connection with the outer screw pipe 71, and the ends of the two threaded inner pipes 72 away from the outer screw pipe 71 are connected with the adjacent connecting plates 63; the surface of the connecting plate 63 is provided with a through hole 631 penetrating to the upper and lower ends, and the first communication pipe 8 extends above the inclined plate 4 after penetrating through the through hole 631;

[0047] The surface of the fixed outer pipe 2 near the screw telescopic pipe 7 is provided with an extension retaining plate 21, the extension retaining plate 21 is symmetrically arranged on the upper and lower ends of the screw telescopic pipe 7, and the extension retaining plate 21 extends towards the middle part of the fixed outer pipe 2;

[0048] In use, by rotating the outer screw pipe 71, the threaded inner pipes 72 on the two sides are respectively extruded outward, the connecting plates 63 are inserted into the soil, and the first communication pipe is sequentially penetrated through the connecting plate 1, the ramming block 5 and the connecting plate 63 and then extends above the inclined plate 4 to pour concrete.

[0049] And, the fixed inner tube 3 lower part is equipped with the outward bulge negative pressure insert piece 31, the negative pressure insert piece 31 inside is equipped with negative pressure assembly 32, and negative pressure assembly 32 includes mounting plate 321, air compressor 322 and communication pipe two 323, mounting plate 321 is formed piston connection with negative pressure insert piece 31 through the sealing ring 3211 of its lower end, and the cavity is formed between mounting plate 321 and negative pressure insert piece 31, air compressor 322 is set up on the upper end of mounting plate 321, and air compressor 322 makes the negative pressure in the cavity through the air outlet 3221 set up in the cavity;The one end of communication pipe two 323 is connected with water pump, and the other end extends to the bottom of negative pressure insert piece 31 through mounting plate 321;The both sides of the lower end of negative pressure insert piece 31 are equipped with permeable membrane layer 311, and the side of permeable membrane layer 311 close to air compressor 322 is equipped with movable closure 312, the movable closure 312 is arranged on the surface of permeable membrane layer 311, and the movable closure 312 includes cover plate 3121, positioning column 3122 and spring 3123, positioning column 3122 is respectively set up on the left and right sides of adjacent permeable membrane layer 311, and penetrates through cover plate 3121, and the spring 3123 is symmetrically set up on the both sides of cover plate 3121 close to positioning column 3122.

[0050] When setting negative pressure insert piece 31 and built-in negative pressure assembly 32 in the lower part of fixed inner tube 3, the surrounding soil can be actively drained and consolidated in situ after the support structure is implanted in soft soil. Specifically, after air compressor 322 is started, the gas in the cavity formed by mounting plate 321 and negative pressure insert piece 31 is continuously sucked out through air outlet 3221, and a stable negative pressure environment is formed in the cavity;The negative pressure is transmitted to the surrounding saturated soft soil through permeable membrane layer 311, which promotes the pore water to enter the inside of negative pressure insert piece 31 through permeable membrane layer 311 under the driving of pressure gradient. To prevent soil particles from entering the cavity with water, permeable membrane layer 311 only allows water molecules to pass through, realizing efficient water filtration and mud blocking. The accumulated water in the bottom of negative pressure insert piece 31 is immediately pumped out by water pump through communication pipe two 323 and discharged to the ground, thereby continuously reducing the water content of the local soil;

[0051] When the negative pressure component 32 operates and creates negative pressure in the internal chamber of the negative pressure insert 31, the air pressure inside the negative pressure insert 31 is significantly lower than the pore water pressure of the external soft soil, thus generating a pressure difference from the outside to the inside on both sides of the permeable membrane layer 311. This pressure difference acts on the outside of the cover plate 3121 of the movable closure component 312, pushing the cover plate 3121 to overcome the preload force of the spring 3123 and slide slightly inward along the positioning post 3122, creating a momentary gap between the cover plate 3121 and the surface of the permeable membrane layer 311. This gap allows pore water to pass through the permeable membrane layer 311 under the pressure difference and smoothly enter the interior of the negative pressure insert 31, achieving efficient water collection. Once the negative pressure stops or the internal and external pressures tend to balance, the spring 3123 pushes the cover plate 3121 to reset, re-adhere tightly to the surface of the permeable membrane layer 311, seal the channel, and prevent backflow of sediment or chamber failure.

[0052] A construction method for a deep foundation pit support structure for soft soil in building construction, based on the aforementioned deep foundation pit support structure for soft soil in building construction, is characterized in that, during construction, a pit is first excavated on the soil surface to accommodate the fixed outer pipe 2 and the fixed inner pipe 3, and a compaction block 5 is placed around the pit. Then, the fixed outer pipe 2 and the fixed inner pipe 3 are installed in the pit in sequence, and the connecting plate 1 is placed against the surface of the compaction block 5 and fixed to the fixed outer pipe 2 by T-shaped reinforcing ribs 11.

[0053] Then, the concrete pouring device is connected through the connecting pipe 8, and after passing through the connecting plate 1, the compaction block 5 and the rectangular telescopic insert plate 6 that fixes the side of the outer pipe 2, it extends to the top of the inclined insert plate 4, and then the concrete is transferred into the soil through the concrete pouring device to form the pouring layer 100.

[0054] The above description is merely a preferred embodiment of the present invention, and therefore should not be construed as limiting the scope of the present invention. All equivalent changes and modifications made in accordance with the scope of the patent and the contents of the specification should still fall within the scope of the present invention.

Claims

1. A support structure for deep foundation pits in soft soil used in building construction, characterized in that, The device includes a connecting plate, a fixed outer pipe, a fixed inner pipe, an inclined insertion plate, and a compaction block. The fixed outer pipe is inserted into the soil, and the connecting plate is fixed to the upper part of the fixed outer pipe by a T-shaped reinforcing rib, with the bottom of the connecting plate abutting against the soil surface. The fixed inner pipe is located on the lower part of the inner side of the fixed outer pipe, with the lower end of the fixed inner pipe abutting against the soil surface. The left and right sides of the connecting plate are raised upwards, and there is a gap between the left and right sides of the connecting plate and the soil surface. The compaction block is placed within this gap. The inclined insertion plate is located on the lower side of the fixed outer pipe, and the inclined insertion plate is inserted into the soil after passing through the fixed inner pipe and the fixed outer pipe in sequence. The fixed outer tube is also equipped with rectangular telescopic inserts and spiral telescopic tubes. The rectangular telescopic inserts are symmetrically arranged on the left and right sides of the fixed outer tube, and all the rectangular telescopic inserts extend through the fixed outer tube into the soil. A spiral telescopic tube is provided between every two opposite rectangular telescopic inserts, and the two ends of the spiral telescopic tube abut against the corresponding rectangular telescopic inserts on both sides. It also includes a connecting pipe that passes through the connecting plate and the compaction block. One end of the connecting pipe is connected to the concrete pouring device, while the other end passes through the connecting plate and the compaction block in sequence and extends to the top of the inclined plate. When the concrete pouring device pours concrete through the connecting pipe, the concrete is transported to the surface of the inclined plate through the connecting pipe and forms a pouring layer on the outside of the inclined plate.

2. The soft soil deep foundation pit support structure for building construction according to claim 1, characterized in that, An angle is formed between two adjacent compacted blocks on the left and right, and multiple connecting rods are fixed between the two adjacent compacted blocks.

3. The soft soil deep foundation pit support structure for building construction according to claim 2, characterized in that, The surface of the compacted block is provided with a bolt, which passes through the connecting plate and is fitted with a washer and a nut. The washer and nut are located on the part of the connecting plate through which the bolt passes, and the nut is located above the washer. The nut is threadedly connected to the bolt. When the nut is rotated clockwise, the connecting plate is pressed downward by adjusting the washer.

4. A soft soil deep foundation pit support structure for building construction according to claim 3, characterized in that, The rectangular telescopic insert is fitted with a square outer tube, a square inner tube, and a connecting insert in sequence from the outside to the inside. The spiral telescopic tube includes an outer spiral tube and a threaded inner tube. The threaded inner tubes are symmetrically arranged on the left and right sides of the outer spiral tube, and the threaded inner tubes on both sides are respectively threaded to the outer spiral tube. The ends of the two threaded inner tubes away from the outer spiral tube are connected to the adjacent connecting insert. The surface of the connecting plate is provided with a through hole extending to both the upper and lower ends, and the connecting tube extends to the top of the inclined plate after passing through the through hole; An extension retaining plate is provided on the surface of the fixed outer tube near the spiral telescopic tube. The extension retaining plate is symmetrically arranged at the upper and lower ends of the spiral telescopic tube and extends toward the middle of the fixed outer tube.

5. A soft soil deep foundation pit support structure for building construction according to claim 4, characterized in that, The lower part of the fixed inner tube is provided with an outwardly protruding negative pressure insertion component. The negative pressure insertion component is provided with a negative pressure assembly inside. The negative pressure assembly includes a mounting plate, an air compressor, and a connecting pipe. The mounting plate is connected to the negative pressure insertion component by a sealing ring at its lower end to form a piston connection. A chamber is formed between the mounting plate and the negative pressure insertion component. The air compressor is located at the upper end of the mounting plate. The air compressor generates negative pressure in the chamber through an air extraction port located in the chamber. One end of the connecting pipe is connected to the water pump, while the other end extends through the mounting plate to the bottom of the negative pressure insert. Both sides of the lower end of the negative pressure insert are provided with permeation membrane layers. The side of the permeation membrane layer closest to the air compressor is covered with a movable closure. The movable closure abuts against the surface of the permeation membrane layer. The movable closure includes a cover plate, positioning posts and springs. The positioning posts are respectively set on the left and right sides of the adjacent permeation membrane layers and pass through the cover plate. The springs are symmetrically arranged on both sides of the cover plate near the positioning posts.

6. A construction method for a deep foundation pit support structure in soft soil for building construction, based on the deep foundation pit support structure in soft soil for building construction described in claim 5, characterized in that, During construction, first excavate a pit on the soil surface to accommodate the fixed outer pipe and the fixed inner pipe, and place tamping blocks around the pit. Then, install the fixed outer pipe and the fixed inner pipe in the pit in sequence, and after the connecting plate is placed against the surface of the tamping block, it is fixed to the fixed outer pipe by T-shaped reinforcing bars. Then, the concrete pouring device is connected through a connecting pipe, and after passing through the connecting plate, the compaction block and the rectangular telescopic insert plate that fixes the side of the outer pipe, it extends to the top of the inclined insert plate. Then, the concrete is transported into the soil to the inclined insert plate through the concrete pouring device, and a pouring layer is formed.

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