Prefabricated pressure-controlled support for foundation pit engineering and application method thereof

Abstract

The present invention relates to a prefabricated pressure-controlled support for foundation pit engineering and its application method, comprising an outer column, the interior of the outer column having a hollow cavity as a water collection chamber, and a three-layer assembled structure of a fixing base, a fixing middle seat, and a limiting top seat respectively arranged at the bottom of the outer column from the lower right to the bottom along the height direction of the outer column, wherein the bottom of the outer column is embedded in the fixing base and the fixing base is provided with a water inlet bottom cavity connected to the water collection chamber of the outer column, the fixing middle seat is arranged above the fixing base and the two are structurally matched, the limiting top seat is arranged above the fixing middle seat and the two are limited to limit the bottom of the outer column; the top of the outer column is provided with an air pressure pump and a water pump connected to the water collection chamber. The advantages of the present invention are: reasonable, innovative, and highly operable, and can effectively control the water pressure of groundwater on the bottom structure of the foundation pit engineering, ensuring the safety of operation and use of underground engineering structures.

Description

Technical Field

[0001] The present invention relates to the technical field of track structures, and in particular to a prefabricated pressure-controlled support column for foundation pit engineering and an application method thereof. Background Art

[0002] In recent years, the country has often needed to carry out foundation pit construction in the process of carrying out various types of infrastructure construction. With the continuous increase in the scale of construction projects and the continuous improvement of my country's infrastructure level and technical capabilities, the scale of foundation pit projects has also become larger and larger, and the size of foundation pits has also become larger and larger. When the foundation pit size is too large and the foundation pit floor is deep, the bottom structure of the foundation pit will be subject to a large force from groundwater. In the existing technology, the means used to deal with the impact of groundwater on the foundation pit floor are mostly passive, that is, changing the engineering design and construction standards of the foundation pit bottom structure. After the foundation pit construction is completed, it can only passively respond to changes in the hydrogeological environment around the foundation pit according to the design standards, and the operational safety and structural safety of the foundation pit project are uncontrollable. Summary of the Invention

[0003] The purpose of the present invention is to provide a prefabricated pressure-controlling support for foundation pit engineering and an application method thereof based on the above-mentioned deficiencies of the prior art. By setting up a pressure-controlling support with controllable pumping and drainage, the changes in the groundwater level around the foundation pit can be monitored in real time and corresponding pressure control strategies can be made in a timely manner. It can be used to regulate the groundwater pressure on the bottom structure of the foundation pit, and the groundwater pumped out under special conditions can be used for daily production water in underground engineering, which can effectively control the water pressure influence of the groundwater on the bottom structure of the foundation pit engineering.

[0004] The purpose of the present invention is achieved by the following technical solutions:

[0005] A prefabricated pressure-controlled pillar for foundation pit engineering, characterized in that it includes an outer column, the interior of the outer column has a hollow cavity serving as a water collecting chamber, and a three-layer assembled structure of a fixing base, a fixing middle seat and a limiting top seat are respectively arranged at the bottom of the outer column along the height direction of the outer column, wherein the bottom of the outer column is embedded in the fixing base and the fixing base is provided with a water inlet bottom cavity connected to the water collecting chamber of the outer column, the fixing middle seat is arranged above the fixing base and the two are structurally matched, the limiting top seat is arranged above the fixing middle seat and the two are limitedly matched to limit the bottom of the outer column; the top of the outer column is provided with an air pressure pump and a water pump connected to the water collecting chamber.

[0006] The limiting top seat is provided with a solid-liquid cavity for storing slurry, and a limiting connection is formed between the limiting top seat and the retaining middle seat by arranging a retaining component, the position of the retaining component corresponds to the position of the solid-liquid cavity, and the retaining component has a top rod that can pierce the solid-liquid cavity.

[0007] A detachable cavity cover is provided on the top of the solid-liquid cavity; a connecting top hole matching the length and diameter of the top rod is opened on the bottom of the solid-liquid cavity, and a cavity protection film is provided between the connecting top hole and the solid-liquid cavity.

[0008] A base vertical plate extending upward in the height direction is provided in the middle position of the retaining base, a retaining ring is formed between the tops of the base vertical plates, and a raised retaining end is provided at the bottom of the outer column, and the retaining end is embedded in the retaining ring.

[0009] A water inlet bottom cavity is formed between the vertical plates of the base, a layer of filter body is provided at the bottom of the water inlet bottom cavity, and two layers of filter body are provided at the retaining end of the bottom of the outer column.

[0010] A middle seat vertical plate is provided on the outer side of the retaining middle seat, and the retaining middle seat limits the limiting top seat through its middle seat vertical plate. The middle part of the limiting top seat has a top seat vertical plate, and the top seat vertical plate limits the outer wall surface of the outer column.

[0011] The top of the outer column is provided with a hollow support top body, a force transmission support and a force adjustment ring. The support top body is in contact with the top surface of the outer column. The air pressure pump and the water pump are placed inside the middle hole of the support top body. The force transmission support is arranged above the support top body, and the force adjustment ring is arranged on the force transmission support.

[0012] A method for applying the prefabricated pressure-controlled support pillar for foundation pit engineering is characterized in that the method comprises the following steps:

[0013] Excavating the foundation pit to the designed depth, placing the retaining base, the retaining middle seat and the limiting top seat one by one at the designed positions, pouring concrete layer by layer to a certain height during the placement of the retaining base, the retaining middle seat and the limiting top seat, fixing the positions of the retaining base, the retaining middle seat and the limiting top seat, and installing a retaining member between the retaining middle seat and the limiting top seat;

[0014] The retaining end of the bottom of the outer column is embedded in the retaining clamp on the top of the retaining base, and the bottom area of the outer column is simultaneously embedded in the inner side of the top seat vertical plate of the limiting top seat;

[0015] Adjust the verticality of the outer column. When the design requirements are met, hammer the limiting top seat with external force to insert the limiting top seat between the middle seat vertical plate of the retaining middle seat and the outer column. At the same time, the retaining member pierces the solid-liquid cavity of the limiting top seat, allowing the slurry in the solid-liquid cavity to flow downward and sequentially penetrate into the contact areas between the retaining base, the retaining middle seat, the limiting top seat and each layer of concrete, thereby achieving secondary reinforcement.

[0016] Remove the cavity cover on the top of the solid-liquid cavity and pour concrete to the designed concrete elevation of the foundation pit bottom;

[0017] The foundation pit supporting structure is supported by the outer column.

[0018] When the groundwater level around the foundation pit rises, the water pump is started to pump out the groundwater. When the water pump is used to pump out the groundwater, the groundwater pumping speed can be increased by starting the air pressure pump. When the groundwater level around the foundation pit drops, the groundwater is reversely pressed into the foundation soil around the foundation pit by the air pressure pump.

[0019] The contact between the force transmission support and the top plate of the foundation pit support structure is adjusted by the force adjusting ring, and the force change of the force adjusting ring is monitored to monitor the change trend of the force acting on the top plate by the upper structure.

[0020] The advantages of the present invention are that it can monitor the changes in the groundwater level around the foundation pit in real time and make pressure control strategies in a timely manner. It is mainly used in foundation pit projects, especially in large-scale foundation pit projects. It can be used to regulate the groundwater pressure on the bottom structure of the foundation pit. The groundwater pumped out under special conditions can be used for daily production water in underground projects. It can monitor the changes in the groundwater level around the foundation pit in real time. It has the advantages of reasonable technical solutions, strong innovation, strong operability, and can effectively control the water pressure influence of groundwater on the bottom structure of the foundation pit project, thereby ensuring the safety of operation and use of underground engineering structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0022] Figure 2 It is an exploded view of the local structure of the present invention. DETAILED DESCRIPTION

[0023] The features of the present invention and other related features are further described in detail below through embodiments in conjunction with the accompanying drawings to facilitate understanding by those skilled in the art:

[0024] like Figure 1-2As shown, the marks 1-43 in the figure respectively represent: outer cylinder 1, fixed base 2, fixed middle seat 3, limited top seat 4, first layer filter body 5, water inlet bottom cavity 6, second layer filter body 7, fixed end 8, fixed clamping ring 9, base bottom plate 10, base vertical plate 11, middle seat bottom plate 12, middle seat vertical plate 13, connecting female hole 14, connecting bottom hole 15, top seat bottom plate 16, top seat vertical plate 17, solid-liquid cavity 18, cavity protective film 19, connecting top hole 20, fixed Component 21, mother rod 22, top rod 23, bottom rod 24, water collecting chamber 25, water level observation hole 26, pillar top body 27, force transmission pillar 28, force adjusting ring 29, air pressure pump 30, water pump 31, inner water pipe 32, outer water pipe 33, water collecting tank 34, pressure regulating plate 35, control equipment 36, first layer of concrete 37, second layer of concrete 38, third layer of concrete 39, fourth layer of concrete 40, top cavity cover 41, foundation pit support structure 42, top plate 43.

[0025] Example: Figure 1 and Figure 2 As shown, the main body of the prefabricated pressure-controlling pillar used in foundation pit engineering in this embodiment includes an outer column 1, which is primarily connected to the foundation pit engineering via a retaining base 2, a retaining middle seat 3, and a limiting top seat 4. During use, it can be used in conjunction with a foundation pit support structure 42 and a top plate 43. This allows the prefabricated pressure-controlling pillar in this embodiment to bear the load of the foundation pit support structure 42 and the top plate 43, thereby serving as part of the foundation pit support structure. Furthermore, its bearing capacity can be adjusted according to the load it bears, thereby ensuring the stability of the foundation pit support structure during the foundation pit engineering.

[0026] like Figure 1 and Figure 2 As shown, the retaining base 2 consists of a base bottom plate 10 and a base vertical plate 11. The base vertical plate 11 is positioned in the middle of the base bottom plate 10 and protrudes upward in the height direction. The base vertical plate 11 is integrally formed with the base vertical plate 11. The bottom area of the protruding portion of the base vertical plate 11 forms a water inlet cavity 6. The bottom of the water inlet cavity 6 is open and connects to the foundation soil at the bottom. A layer of filter 5 is distributed in the center of the water inlet cavity 6 near the base bottom plate 10. Groundwater contained in the foundation soil of the foundation pit can be initially filtered by the filter 5 and then collected in the water inlet cavity 6. The top areas of the raised portions of the base vertical plates 11 extend toward each other and raise a certain distance, thereby forming a retaining ring 9. The inner ring diameter of the retaining ring 9 matches the outer contour size of the fixed end 8 at the bottom of the outer column 1, so that the outer column 1 can be embedded in the retaining ring 9 through its fixed end 8 at the bottom, thereby preliminarily combining the outer column 1 with the retaining base 2.

[0027] The retaining center seat 3 is composed of a center seat bottom plate 12 and a center seat vertical plate 13. The center seat vertical plate 13 is located outside the center seat bottom plate 12 and is integrally formed with the center seat bottom plate 12. The upper surface of the center seat bottom plate 12 is concave in sequence to form a connecting female hole 14 and a connecting bottom hole 15 with gradually decreasing inner diameters.

[0028] The limiting top seat 4 is composed of a top seat base plate 16 and a top seat vertical plate 17. The top seat vertical plate 17 is located inside the top seat base plate 16 and is integrally formed with the top seat base plate 16. A solid-liquid cavity 18 is distributed within the top seat base plate 16. This solid-liquid cavity 18 can store slurry used for secondary reinforcement of the component structure. The cavity cover 41 at the top of the solid-liquid cavity 18 is closed after the slurry is poured. The slurry can only communicate with the outside world through the connecting top hole 20 also located within the top seat base plate 16. The connection between the connecting top hole 20 and the solid-liquid cavity 18 is distributed with a cavity protection film 19.

[0029] The position-limiting top seat 4 and the retaining middle seat 3 are connected by a retaining member 21. The retaining member 21 is composed of a top rod 23, a female rod 22, and a bottom rod 24 from top to bottom. The female rod 22 and the bottom rod 24 can be inserted into the female connection hole 14 and the bottom connection hole 15 on the middle seat bottom plate 12 of the retaining middle seat 3. The top rod 23 can be inserted into the top connection hole 20 located below the top seat bottom plate 16 of the position-limiting top seat 4. The length of the top rod 23 is slightly larger than the depth of the top connection hole 20. When the position-limiting top seat 4 is connected to the retaining middle seat 3 via the retaining member 21, the top rod 23 can pierce the cavity protective film 19, thereby causing the slurry inside the solid-liquid cavity 18 to flow out. At the same time, since the top rod 23 of the retaining member 21 is located in the connecting top hole 20, and the mother rod 22 and the bottom rod 24 are located in the connecting mother hole 14 and the connecting bottom hole 15, the retaining member 21 can also limit the connection between the retaining middle seat 3 and the limiting top seat 4, especially limiting the displacement of the two in the horizontal direction to avoid misalignment between the two.

[0030] The bottom size of the top seat bottom plate 16 is equivalent to the size of the top of the middle seat bottom plate 12 excluding the middle seat vertical plate 13. The bottom size of the middle seat bottom plate 12 is equivalent to the size of the top area of the base bottom plate 10 excluding the base vertical plate 11. The top seat vertical plate 17 is located on the inner side of the top seat bottom plate 16, the middle seat vertical plate 13 is located on the outer side of the middle seat bottom plate 12, and the base vertical plate 11 is convex on the inner side of the base bottom plate 10. This structural method can ensure that after the slurry in the solid-liquid cavity 18 flows out, it can gradually penetrate into any contact part of the retaining base 2, the retaining middle seat 3, and the limiting top seat 4, and can give full play to the secondary reinforcement effect of the slurry in the solid-liquid cavity 18 on the component connection.

[0031] A second layer of filter elements 7 is located within the fixed end 8 at the bottom of the outer cylinder 1. The outer cylinder 1 is hollow, and this internal cavity serves as a water collection chamber 25. The bottom of this water collection chamber 25 is connected to the fixed end 8 at the bottom of the outer cylinder 1. Groundwater within the water inlet chamber 6 is further filtered by the secondary filter elements 7 before being collected into the water collection chamber 25. Water level observation holes 26 are located on the outer surface of a certain area of the outer cylinder 1, allowing operators to monitor water level changes in the water collection chamber 25.

[0032] The top of the outer column 1 is provided with a support top body 27 and a central hole inside the support top body 27, which is mainly used to place the air pressure pump 30 and the water pump 31. The support top body 27 is in contact with the top plate 43 through the force transmission support 28. The contact degree between the force transmission support 28 and the top plate 43 can be adjusted by the force adjustment ring 29 on the force transmission support 28. When the force transmission support 28 is separated from the top plate 43, the outer column 1 does not have to bear the upper structure force transmitted by the top plate 43. When the force transmission support 28 is in close contact with the top plate 43, the outer column 1 can bear the upper structure force transmitted by the top plate 43. The force adjustment ring 29 has a stress monitoring function. When the force transmission support 28 is in contact with the top plate 43, the deformation trend of the top plate 43 under the action of the upper structure can be monitored in real time by comparing the force of the force transmission support 28 in different time periods. Under the action of the pump 31, the groundwater in the water collection chamber 25 can be introduced into the water collection box 34 located outside the outer column 1 through the inner water pipe 32 and the outer water pipe 33. The air pressure pump 30 is connected to the pressure regulating plate 35 located at the top of the water collection chamber 25. The air pressure pump 30 can adjust the atmospheric pressure in the water collection chamber 25, generating additional atmospheric pressure on the groundwater in the water collection chamber 25, thereby controlling the inflow or outflow of groundwater from the surrounding foundation pit into the water collection chamber 25. This can adjust the effect of the groundwater on the foundation pit bottom according to the changes in the groundwater level around the foundation pit, thereby adjusting the support effect of the pressure-controlled pillars in this embodiment on the foundation pit support structure. The operating status of the pump 31 and the air pressure pump 30 can be controlled by the control device 36.

[0033] The column shape of the pressure control pillar in this embodiment can be round or square, which can be selected according to the needs of the site. Taking the pressure control pillar as a round one as an example, the pressure control pillar in this embodiment has the following application methods:

[0034] (1) After the foundation pit is excavated to the designed depth, the debris at the bottom of the foundation pit should be cleaned up.

[0035] (2) Place the retaining base 2 at the designed position.

[0036] (3) Pour a layer of concrete 37, the thickness of which is the same as the height of the base bottom plate 10, to perform preliminary limiting fixation on the retaining base 2.

[0037] (4) During the initial setting of the concrete, the flatness and horizontal position of the retaining base 2 are monitored and fine-tuned in real time to improve the construction accuracy, especially to ensure the verticality of the outer column 1 that is embedded and connected to the retaining base 2.

[0038] (5) Pour a second layer of concrete 38. The pouring thickness of the second layer of concrete 38 is the height of the base vertical plate 11 minus the height of the middle base bottom plate 12. The second layer of concrete 38 exerts a force on the surface of the base bottom plate 10 in the height direction, thereby fixing the position of the fixed base 2.

[0039] (6) After the second layer of concrete 38 is poured, place the retaining seat 3 and put the retaining seat 3 around the base vertical plate 11, and pay attention to ensure the fit between the bottom of the retaining seat 3 and the second layer of concrete 38.

[0040] (7) Pour three layers of concrete 39. The pouring thickness of the three layers of concrete 39 may not be higher than the height of the middle seat vertical plate 13. During the pouring process, pay attention to real-time monitoring and adjustment of the spatial position of the fixed middle seat 3 to ensure that the middle seat bottom plate 12 is level.

[0041] (8) Insert the retaining member 21 into the middle seat bottom plate 12, so that the female rod 22 and the bottom rod 24 are inserted into the connecting female hole 14 and the connecting bottom hole 15 in sequence.

[0042] (9) Check the working status of the water collecting chamber 25 in the outer column 1, the water pump 31 in the support top body 27, the air pressure pump 30, the control equipment 36, etc., and debug them.

[0043] (10) Place the limiting top seat 4 above the retaining middle seat 3, and initially insert the push rod 23 into the connecting top hole 20 of the limiting top seat 4. Under the action of the self-weight of the limiting top seat 4, the push rod 23 will not temporarily damage the cavity protective film 19. At this time, there is still slurry for secondary reinforcement in the solid-liquid cavity 18 of the limiting top seat 4.

[0044] (11) The retaining end 8 at the bottom of the outer column 1 is embedded in the retaining clamp 9 at the top of the retaining base 2, and the bottom area of the outer column 1 is simultaneously embedded in the inner side of the top seat vertical plate 17.

[0045] (12) Adjust the verticality of the outer column 1. When the design requirements are met, hammer the limit top seat 4 with external force to put the limit top seat 4 in place. The limit top seat 4 is inserted between the middle seat vertical plate 13 and the outer column 1. At this time, the push rod 23 pierces the cavity protective film 19, and the slurry stored in the solid-liquid cavity 18 flows downward and penetrates into the contact areas between the limit top seat 4, the retaining middle seat 3, the retaining base 2, the first layer of concrete 37, the second layer of concrete 38, and the third layer of concrete 39 in turn, thus performing secondary reinforcement on the construction of the entire pressure control pillar.

[0046] (13) Remove the chamber cover 41 on the top of the solid-liquid chamber 18.

[0047] (14) Pour four layers of concrete 40 to the designed elevation of the foundation pit bottom concrete. The pouring thickness of the four layers of concrete 40 can be higher than the height of the top seat vertical plate 17. At this time, since the reinforcing slurry in the solid-liquid cavity 18 has seeped out and the cavity cover 41 has been removed, a limiting structure is formed between the four layers of concrete 40 and the empty solid-liquid cavity 18. That is, the four layers of concrete 40 flowing into the solid-liquid cavity 18 form a limiting structure for the limiting top seat 4, ensuring that it will not move in the horizontal direction.

[0048] In this embodiment, through the cooperation between the three-layer assembled support structure, namely the retaining base 2, the retaining center 3 and the limiting top seat 4, not only the high-precision construction of the outer column 1 is achieved, but also each layer of concrete can cooperate with each other to produce a certain pressure effect on the foundation soil below, so that groundwater can flow into the water collection chamber 25 of the outer column 1 under pressure.

[0049] The pressure control pillar in this embodiment has the following working scenarios:

[0050] (1) Affected by environmental factors such as rainfall, when the groundwater level around the foundation pit rises, the water pressure of the groundwater on the bottom structure of the foundation pit increases. Due to the presence of preload pillars, part of the groundwater can be collected into the water collection cavity 25 through the water inlet cavity 6, thereby reducing the water pressure of the groundwater on the bottom structure of the foundation pit. If the natural collection of groundwater cannot effectively cope with the rising height of the groundwater, the groundwater can be pumped into the water collection tank 34 by starting the water pump 31 for storage. The groundwater in the water collection tank 34 can be used for daily production and firefighting water for the units using the underground structure. When the groundwater rises suddenly or is affected by other special extreme environments, and natural pumping cannot meet the time requirements, the air pressure pump 30 can be controlled to generate negative pressure in the water collection tank 34 to increase the pumping speed of the groundwater.

[0051] (2) When the groundwater level drops seriously and affects the stability of the foundation soil around the foundation pit, the hydrogeological environment around the foundation pit can be maintained by injecting groundwater into the water collection chamber 25. When the need can be met by injecting an appropriate amount of existing groundwater into the water collection chamber 25, the pressure in the water collection chamber 25 can be controlled by adjusting the air pressure pump 30 to reversely press the groundwater into the foundation soil around the foundation pit.

[0052] (3) When the pressure-control pillar needs to bear the external structural force, the force-transmitting pillar 28 can be adjusted to contact the top plate 43 through the force-adjusting ring 29. At this time, the pressure-control pillar can bear the upper structural force transmitted by the top plate 43. By monitoring the force changes of the force-adjusting ring 29 in real time, the changing trend of the upper structural force on the top plate 43 can also be monitored, providing ready-made monitoring data for the safety of the foundation pit structure.

[0053] During the specific implementation of this embodiment: the outer column 1 can be made of reinforced concrete material with a certain compressive resistance and a certain structural stability, and the retaining base 2, the retaining middle seat 3, the limiting top seat 4, the support top body 27, etc. can be made of steel plates, alloy materials or concrete materials with a certain deformation resistance. The cavity protection membrane 19 can be made of a rubber material with a certain elasticity. The force transmission support 28 and the retaining member 21 can be made of steel or alloy materials. The water collection chamber 25 can be made of a composite plastic material with a certain structural stability and good transparency. The protective shell of the water level observation hole 26 is made of a transparent composite plastic material. The water pump 31, the air pressure pump 30, the control equipment 36, the force adjustment ring 29, etc. can adopt existing market technologies.

[0054] The embedding method of the retaining base 2, the retaining middle seat 3, the limiting top seat 4, the retaining member 21, the bottom fixed end 8 of the outer column 1 and the retaining clamp 9 is not limited, and can be directly embedded or threaded embedded.

[0055] Although the above embodiments have described in detail the concepts and embodiments of the present invention with reference to the accompanying drawings, ordinary technicians in this field can recognize that various improvements and modifications can still be made to the present invention without departing from the scope of the claims, so they are not described in detail here.

Claims

1. A prefabricated pressure-controlled support for foundation pit engineering, characterized by: The invention comprises an outer column, wherein the interior of the outer column has a hollow cavity as a water collecting chamber, and a three-layer assembled structure of a retaining base, a retaining middle seat and a limiting top seat are respectively arranged on the bottom of the outer column along the height direction of the outer column, wherein the bottom of the outer column is embedded in the retaining base and the retaining base is provided with a water inlet bottom cavity connected with the water collecting chamber of the outer column, the retaining middle seat is arranged above the retaining base and the two are structurally matched, the limiting top seat is arranged above the retaining middle seat and the two are limitedly matched to limit the bottom of the outer column; the top of the outer column is provided with an air pressure pump and a water pump connected with the water collecting chamber; The position-limiting top seat is provided with a solid-liquid cavity for storing slurry, and a position-limiting connection is formed between the position-limiting top seat and the retaining middle seat by providing a retaining member, the position of the retaining member corresponds to the position of the solid-liquid cavity, and the retaining member has a push rod capable of piercing the solid-liquid cavity; A detachable cavity cover is provided on the top of the solid-liquid cavity; a connecting top hole matching the length and diameter of the top rod is opened on the bottom of the solid-liquid cavity, and a cavity protection film is provided between the connecting top hole and the solid-liquid cavity.

2. The prefabricated pressure-controlled support for foundation pit engineering according to claim 1, characterized in that: A base vertical plate extending upward in the height direction is provided in the middle position of the retaining base, a retaining ring is formed between the tops of the base vertical plates, and a raised retaining end is provided at the bottom of the outer column, and the retaining end is embedded in the retaining ring.

3. The prefabricated pressure-controlled support for foundation pit engineering according to claim 2, characterized in that: A water inlet bottom cavity is formed between the vertical plates of the base, a layer of filter body is provided at the bottom of the water inlet bottom cavity, and two layers of filter body are provided at the retaining end of the bottom of the outer column.

4. The prefabricated pressure-controlled support for foundation pit engineering according to claim 1, characterized in that: A middle seat vertical plate is provided on the outer side of the retaining middle seat, and the retaining middle seat limits the limiting top seat through its middle seat vertical plate. The middle part of the limiting top seat has a top seat vertical plate, and the top seat vertical plate limits the outer wall surface of the outer column.

5. The prefabricated pressure-controlled support for foundation pit engineering according to claim 1, characterized in that: The top of the outer column is provided with a hollow support top body, a force transmission support and a force adjustment ring. The support top body is in contact with the top surface of the outer column. The air pressure pump and the water pump are placed inside the middle hole of the support top body. The force transmission support is arranged above the support top body, and the force adjustment ring is arranged on the force transmission support.

6. A method for applying the prefabricated pressure-controlled support for foundation pit engineering according to any one of claims 1 to 5, characterized in that: The application method comprises the following steps: Excavating the foundation pit to the designed depth, placing the retaining base, the retaining middle seat and the limiting top seat one by one at the designed positions, pouring concrete layer by layer to a certain height during the placement of the retaining base, the retaining middle seat and the limiting top seat, fixing the positions of the retaining base, the retaining middle seat and the limiting top seat, and installing a retaining member between the retaining middle seat and the limiting top seat; The retaining end of the bottom of the outer column is embedded in the retaining clamp on the top of the retaining base, and the bottom area of the outer column is simultaneously embedded in the inner side of the top seat vertical plate of the limiting top seat; Adjust the verticality of the outer column. When the design requirements are met, hammer the limiting top seat with external force to insert the limiting top seat between the middle seat vertical plate of the retaining middle seat and the outer column. At the same time, the retaining member pierces the solid-liquid cavity of the limiting top seat, allowing the slurry in the solid-liquid cavity to flow downward and sequentially penetrate into the contact areas between the retaining base, the retaining middle seat, the limiting top seat and each layer of concrete, thereby achieving secondary reinforcement. Remove the cavity cover on the top of the solid-liquid cavity and pour concrete to the designed concrete elevation of the foundation pit bottom; The foundation pit supporting structure is supported by the outer column.

7. The method for applying a prefabricated pressure-controlled support for foundation pit engineering according to claim 6, characterized in that: When the groundwater level around the foundation pit rises, the water pump is started to pump out the groundwater. When the water pump is used to pump out the groundwater, the groundwater pumping speed can be increased by starting the air pressure pump. When the groundwater level around the foundation pit drops, the groundwater is reversely pressed into the foundation soil around the foundation pit by the air pressure pump.

8. The method for applying a prefabricated pressure-controlled support for foundation pit engineering according to claim 6, characterized in that: The contact between the force transmission support and the top plate of the foundation pit support structure is adjusted by the force adjusting ring, and the force change of the force adjusting ring is monitored to monitor the change trend of the force acting on the top plate by the upper structure.

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