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

Abstract

The invention 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 of the soft soil deep foundation pit supporting structure for building construction. The problem that in the background technology, a soft soil deep foundation pit supporting structure is prone to inclining, loosening and even collapsing is effectively solved, the fixed outer pipe serves as a main force bearing framework and is matched with the inclined inserting plate obliquely penetrating into a deep soil body from the bottom of the fixed outer pipe, an anti-sliding anchoring system is formed, and the anti-overturning capacity is remarkably improved; the connecting plate is rigidly connected with the fixing outer pipe through the T-shaped reinforcing ribs, the tamping blocks are arranged in the gaps formed between the two protruding sides of the connecting plate and the earth surface, the earth surface can be tamped in advance before installation, the compactness of shallow soil is enhanced, root instability is prevented, the overall structure is suitable for large and deep foundation pits with soft soil, and the supporting stability and the construction safety are greatly improved.

Description

Technical Field

[0001] This invention relates to the field of foundation pit support structures, specifically a soft soil deep foundation pit support structure for building construction and its support construction method. Background Technology

[0002] Conventional deep foundation pit support structures suitable for hard soil typically employ pile drivers to insert support plates one by one along the edge of the pit into the ground. This support structure is relatively simple, as the inserted end can be fixed in the soil. However, for soft soil, the inserted end will tilt as the soil moves, thus losing its support effect. In severe cases, slope collapse and support plate detachment may occur. Although support rods are installed in small foundation pits to support the upper end of the support plates, for large and deep foundation pits, the distance between two support plates can be tens of meters, making it impractical to support the upper end of the support plates 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 as the underground soil moves, thus losing its support effect. Summary of the Invention

[0003] This invention provides a support structure for deep foundation pits in soft soil for building construction and a support construction method thereof, which overcomes the shortcomings described in the background art.

[0004] The technical solution adopted by this invention to solve its technical problem is: A deep foundation pit support structure for soft soil in building construction 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 located within the 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 connecting plate is also provided with rectangular telescopic inserts and spiral telescopic tubes. The rectangular telescopic inserts are symmetrically arranged on the left and right sides of the connecting plate, and all the rectangular telescopic inserts extend through the connecting plate 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.

[0005] A preferred technical solution is 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.

[0006] In a preferred embodiment, 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 and the bolt are connected by a thread. When the nut is rotated clockwise, the connecting plate is pressed downward by adjusting the washer.

[0007] A preferred technical solution further 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.

[0008] In a preferred embodiment, the rectangular telescopic insert is provided 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.

[0009] In a preferred embodiment, 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 provided 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 provided at the upper end of the mounting plate. The air compressor generates negative pressure in the chamber through an air extraction port provided 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.

[0010] 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 for accommodating a fixed outer pipe and a fixed inner pipe is first excavated on the soil surface, and compacted blocks are placed around the pit. Then, the fixed outer pipe and the fixed inner pipe are installed in the pit in sequence, and after the connecting plate is placed against the surface of the compacted 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, and then the concrete is transferred into the soil through the concrete pouring device to form a pouring layer.

[0011] Compared with existing technologies, this technical solution has the following advantages: This invention effectively solves the problem of easy tilting, loosening, or even collapse of the support structure for deep foundation pits in soft soil in the background art. By using the fixed outer pipe as the main load-bearing skeleton and cooperating with the inclined insertion plate that penetrates the deep soil from the bottom, an anti-sliding anchoring system is formed, which significantly improves the anti-overturning capacity. The connecting plate is rigidly connected to the fixed outer pipe through T-shaped reinforcing bars. The gap formed between the raised sides and the ground surface is filled with compacted blocks, which can pre-compact the surface before installation, enhance the density of the shallow soil, and prevent root instability. The overall structure is suitable for soft soil and large and deep foundation pits, which greatly improves the support stability and construction safety. Attached Figure Description

[0012] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0013] Figure 1 This is an overall diagram of the present invention.

[0014] Figure 2 This is a schematic diagram of the structure after the rectangular telescopic insert is unfolded and the cast layer is formed.

[0015] Figure 3 for Figure 2 Enlarged schematic diagram of point b in the middle.

[0016] Figure 4 for Figure 2 Enlarged diagram of point a in the image.

[0017] Figure 5 for Figure 1 Top view diagram.

[0018] Figure 6 This is a schematic diagram of the rectangular telescopic insert and the spiral telescopic tube.

[0019] Figure 7 This is a schematic diagram of an extended retaining plate.

[0020] Figure 8This is a schematic diagram of the negative pressure insertion device and the negative pressure assembly.

[0021] Figure 9 This is a schematic diagram of the internal structure of the negative pressure insertion device.

[0022] In the diagram: 1. Connecting plate; 2. Fixed outer pipe; 3. Fixed inner pipe; 4. Inclined insert plate; 5. Compacted block; 6. Rectangular telescopic insert plate; 7. Spiral telescopic pipe; 8. Connecting pipe 1; 100mm pouring layer. 11 T-shaped reinforcing ribs; Extension retaining plate 21; Negative pressure insert 31, permeable membrane layer 311, movable closure 312, cover plate 3121, positioning post 3122, spring 3123, negative pressure assembly 32, mounting plate 321, sealing ring 3211, air compressor 322, air extraction port 3221; Bolt 51, washer 52, nut 53, connecting rod 54; Square outer tube 61, square inner tube 62, connecting plate 63, through hole 631; External spiral tube 71, internal threaded tube 72. Detailed Implementation

[0023] like Figures 1 to 9 As shown, this invention proposes a support structure for deep foundation pits in soft soil for building construction, including a connecting plate 1, a fixed outer pipe 2, a fixed inner pipe 3, an inclined insertion plate 4, and a compaction block 5. The fixed outer pipe 2 is inserted into the soil, and the connecting plate 1 is fixed to the upper part of the fixed outer pipe 2 by a T-shaped reinforcing rib 11, with the bottom of the connecting plate 1 abutting against the soil surface. The fixed inner pipe 3 is located on the lower part of the inner side of the fixed outer pipe 2, with the lower end of the fixed inner pipe 3 abutting against the soil surface. The left and right sides of the connecting plate 1 are raised upwards, and there is a gap between the left and right sides of the connecting plate 1 and the soil surface. The compaction block 5 is located within this gap. The inclined insertion plate 4 is located on the lower side of the fixed outer pipe 2, and the inclined insertion plate 4 is inserted into the soil after passing through the fixed inner pipe 3 and the fixed outer pipe 2 in sequence. The connecting plate 1 is also provided with a rectangular telescopic insert 6 and a spiral telescopic tube 7. The rectangular telescopic insert 6 is symmetrically arranged on the left and right sides of the connecting plate 1, and all the rectangular telescopic insert 6 extends through the connecting plate 1 into the soil. A spiral telescopic tube 7 is provided between every two opposite rectangular telescopic insert 6, and the two ends of the spiral telescopic tube 7 abut against the corresponding rectangular telescopic insert 6 on both sides.

[0024] During construction, the outer fixed pipe 2 is first vertically pressed into the soft soil to the design depth, serving as the main load-bearing framework. Then, an inner fixed pipe 3 is placed inside the lower part of the outer fixed pipe 2, with its lower end only touching the ground surface. Its main function is to provide guidance and a passage for the inclined insertion plate 4, and to enhance the local pipe wall rigidity. The inclined insertion plate 4 penetrates the deep stable soil layer at an angle from the bottom of the outer fixed pipe 2, forming a structure similar to a micro-anti-slide pile. This effectively resists the overturning moment generated by earth pressure, preventing the entire support system from tilting.

[0025] The connecting plate 1 is rigidly connected to the top of the fixed outer pipe 2 via T-shaped reinforcing ribs 11, with its bottom surface pressed tightly against the ground surface, limiting the displacement of the top of the support structure. Simultaneously, the left and right sides of the connecting plate 1 bulge upwards, forming a gap with the ground surface. This gap is filled with compacted blocks 5, which locally compact the disturbed surface soil, inhibiting root loosening caused by shallow soil flow. Specifically, the compacted blocks 5 can be pre-pressed or tamped onto the ground surface before the support structure is installed, pre-reinforcing the shallow soft soil and significantly improving the surface bearing capacity and density.

[0026] Furthermore, an angle is formed between two adjacent compacted blocks 5 on the left and right, and multiple connecting rods 54 are fixed between two adjacent compacted blocks 5.

[0027] Furthermore, the surface of the compaction block 5 is provided with a bolt 51, which passes through the connecting plate 1 and is fitted with a washer 52 and a nut 53. The washer 52 and the nut 53 are located on the part of the surface through which the bolt 51 passes through the connecting plate 1, and the nut 53 is located above the washer 52. The nut 53 and the bolt 51 are connected by a thread. When the nut 53 is rotated clockwise, the connecting plate 1 is pressed downward by adjusting the washer 52.

[0028] As described above, in this invention, the bolt 51 vertically penetrates the raised side of the connecting plate 1, and a washer 52 and a nut 53 are sequentially fitted at the end of the bolt that protrudes from the upper surface of the connecting plate 1. The washer 52 fits against the upper surface of the connecting plate 1 to increase the stress area and prevent local crushing. The nut 53 forms a threaded connection with the exposed threaded section of the bolt 51 and is located above the washer 52. After the initial installation of the support structure, if a small gap is found between the bottom of the connecting plate 1 and the ground surface, or if the shallow soft soil is not dense enough due to disturbance, the operator can use a wrench or other tools to rotate the nut 53 clockwise. As the nut 53 is screwed down along the bolt 51, its bottom surface gradually presses against the washer 52, thereby applying a controllable, vertically downward preload to the connecting plate 1. This force is transmitted through the connecting plate 1 to the soil surface it contacts at the bottom, and simultaneously acts in the opposite direction on the compaction block 5 below, forcing the compaction block 5 to further embed or compact the soft soil layer below it.

[0029] Furthermore, the support structure also includes a connecting pipe 8 that passes through the connecting plate 1 and the compaction block 5. One end of the connecting pipe 8 is connected to the concrete pouring device, while the other end passes through the connecting plate 1 and the compaction block 5 in sequence and extends to the top of the inclined plate 4. When the concrete pouring device pours concrete through the connecting pipe 8, the concrete is transported to the surface of the inclined plate 4 through the connecting pipe 8 and forms a pouring layer 100 on the outside of the inclined plate 4. The installation of the connecting pipe 8 allows concrete to be precisely injected directly from the ground surface into the area above the inclined plate 4, preventing the grout from spreading out of control or being lost in the soft soil, and ensuring that the reinforcement position is controllable. After the resulting pouring layer 100 solidifies on the outside of the inclined plate 4, it not only significantly improves the bond strength and integrity with the surrounding soil, but also transforms the original support mechanism that relied on passive earth pressure into an active anchoring system. This effectively inhibits the accumulation of displacement caused by soft soil creep and enhances the structure's resistance to deformation under long-term loads, thereby greatly improving the stability and reliability of the entire support system. Furthermore, after the concrete is poured, there is no need to remove the connecting pipe 8, allowing the connecting pipe 8 and the solidified concrete to simultaneously fix the support structure.

[0030] Furthermore, the rectangular telescopic insert 6 is fitted with a square outer tube 61, a square inner tube 62, and a connecting insert 63 sequentially from the outside to the inside. The spiral telescopic tube 7 includes an outer spiral tube 71 and a threaded inner tube 72. The threaded inner tubes 72 are symmetrically arranged on the left and right sides of the outer spiral tube 71, and the threaded inner tubes 72 on both sides are threadedly connected to the outer spiral tube 71. The ends of the two threaded inner tubes 72 away from the outer spiral tube 71 are connected to the adjacent connecting insert 63. The surface of the connecting insert 63 is provided with a through hole 631 that extends to both the upper and lower ends. The connecting tube 8 passes through the through hole 631 and extends to the top of the inclined insert 4. An extension retaining plate 21 is provided on the surface of the fixed outer tube 2 near the spiral telescopic tube 7. The extension retaining plate 21 is symmetrically arranged at the upper and lower ends of the spiral telescopic tube 7 and extends toward the middle of the fixed outer tube 2. In use, by rotating the outer spiral tube 71, the threaded inner tubes 72 on both sides are pushed outwards respectively, the connecting plate 63 is inserted into the soil, and the connecting pipe is passed through the connecting plate 1, the compaction block 5 and the connecting plate 63 in sequence and then extended to the inclined plate 4 to pour concrete.

[0031] Furthermore, the lower part of the fixed inner tube 3 is provided with an outwardly protruding negative pressure insertion component 31. A negative pressure assembly 32 is provided inside the negative pressure insertion component 31. The negative pressure assembly 32 includes a mounting plate 321, an air compressor 322, and a connecting pipe 323. The mounting plate 321 is connected to the negative pressure insertion component 31 via a sealing ring 3211 at its lower end, forming a piston connection. A chamber is formed between the mounting plate 321 and the negative pressure insertion component 31. The air compressor 322 is located at the upper end of the mounting plate 321 and generates negative pressure within the chamber through an air extraction port 3221 located within the chamber. One end of the connecting pipe 323 is connected to a water pump, while the other end... One end extends through the mounting plate 321 to the bottom of the negative pressure insertion component 31; both sides of the lower end of the negative pressure insertion component 31 are provided with permeation membrane layers 311, and the side of the permeation membrane layer 311 near the air compressor 322 is covered with a movable closure component 312. The movable closure component 312 abuts against the surface of the permeation membrane layer 311, and the movable closure component 312 includes a cover plate 3121, a positioning post 3122 and a spring 3123. The positioning post 3122 is respectively arranged on the left and right sides of the adjacent permeation membrane layer 311 and passes through the cover plate 3121. The spring 3123 is symmetrically arranged on both sides of the cover plate 3121 near the positioning post 3122.

[0032] By installing a negative pressure insert 31 and a built-in negative pressure component 32 at the lower part of the fixed inner pipe 3, in-situ drainage and consolidation of the surrounding soil can be actively achieved after the soft soil is implanted into the support structure. Specifically, after the air compressor 322 is started, the gas in the chamber formed by the mounting plate 321 and the negative pressure insert 31 is continuously extracted through the air extraction port 3221, creating a stable negative pressure environment in the chamber. This negative pressure is transmitted to the surrounding saturated soft soil through the permeable membrane layer 311, causing pore water to pass through the permeable membrane layer 311 and enter the interior of the negative pressure insert 31 under the pressure gradient. To prevent soil particles from entering the chamber with the water flow, the permeable membrane layer 311 only allows water molecules to pass through, achieving efficient water filtration and mud blocking. The water that enters the bottom of the negative pressure insert 31 is then pumped out by the water pump through the connecting pipe 323 and discharged to the ground, thereby continuously reducing the local soil moisture content. 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.

[0033] 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 the T-shaped reinforcing rib 11. 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.

[0034] 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 connecting plate is also provided with rectangular telescopic inserts and spiral telescopic tubes. The rectangular telescopic inserts are symmetrically arranged on the left and right sides of the connecting plate, and all the rectangular telescopic inserts extend through the connecting plate 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.

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 and the bolt are connected by a thread. 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, 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.

5. A soft soil deep foundation pit support structure for building construction according to claim 4, 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.

6. A soft soil deep foundation pit support structure for building construction according to claim 5, 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.

7. 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 6, 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, and then the concrete is transferred into the soil through the concrete pouring device to form a pouring layer.

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