Device, system and method for active pressure-based control of deformation in passive zone in foundation pit engineering

Abstract

Disclosed in the present invention are a device, system and method for active pressure-based control of deformation in a passive zone in foundation pit engineering. The device, system and method for active pressure-based control of deformation in the present invention involve a reaction pile (1), a counter-pressure base plate (3) and a counter-pressure control device (2); the reaction pile is arranged in a soil body at the bottom of a foundation pit; the counter-pressure base plate covers the soil body at the bottom of the foundation pit; the counter-pressure control device comprises a top force transmission structure (2-2) and loading devices (2-1); the top force transmission structure is firmly connected to the reaction pile; a loading device accommodating space is provided between the top force transmission structure and the counter-pressure base plate; the loading devices are arranged in the loading device accommodating space; the loading devices apply downward dynamic pressure to the counter-pressure base plate on the basis of the top force transmission structure. The device, system and method for active pressure-based control of deformation in the present invention can achieve a good control effect on upward deformation of a soil body in a passive zone of the bottom of a foundation pit.

Description

Passive zone pressure deformation active control device, system and method for foundation pit engineering TECHNICAL FIELD

[0001] The present application relates to a foundation pit engineering construction technology, in particular to a passive zone pressure deformation active control device, system and method for foundation pit engineering. BACKGROUND

[0002] With the continuous development of urban underground space development, foundation pit engineering is developing towards deeper and larger directions, which puts forward higher requirements for foundation pit deformation control. However, when excavating a foundation pit in soft soil areas, the soft soil has low strength, high sensitivity, and weak lateral constraint effect on the pit bottom, which easily leads to insufficient resistance provided by the passive zone of the pit bottom, thereby causing excessive deformation of the pit bottom and further causing deformation of the retaining wall and surrounding buildings.

[0003] At present, the method of pre-reinforcing the soil of the foundation pit is commonly used to improve the resistance of the passive zone soil in the pit, reduce the compression of the soil and the displacement of the retaining wall, and thus reduce the impact of foundation pit excavation on the surrounding environment. Common reinforcement methods include compaction grouting, rotary jet grouting, and soil-cement pile reinforcement. In order to further control in detail, some active control technologies are proposed, involving the following patents:

[0004] Patent 1: Reinforcing structure for passive zone of foundation pit in deep soft soil area (publication number: CN215562677U, publication date: January 18, 2022).

[0005] The utility model provides a reinforcing structure for passive zone of foundation pit in deep soft soil area. The reinforcing structure comprises a foundation pit retaining pile, a passive zone at the bottom of the foundation pit adjacent to the foundation pit retaining pile, and a plurality of variable cross-section cement-soil piles with large upper sections and small lower sections constructed in the passive zone at the bottom of the foundation pit in the deep soft soil area; the variable cross-section cement-soil piles comprise upper cement-soil piles with diameters of 0.8-1.2 m and lower cement-soil piles with diameters of 0.4-0.6 m, the upper cement-soil piles of the plurality of variable cross-section cement-soil piles are mutually overlapped and engaged, the lower cement-soil piles are not mutually overlapped, and the lower cement-soil pile of each variable cross-section cement-soil pile penetrates through the deep soft soil layer and is placed in the hard soil layer. The utility model has the advantages of simple structure, simple piling process, effective improvement of the passive resistance of the entire soft soil layer, and guarantee of the safety of the foundation pit.

[0006] The patent has the following disadvantages:

[0007] (1) The high-pressure rotary jet machine is used to construct the variable cross-section cement-soil piles in the soft soil area, and the cement is easily wrapped into lumps, so the piling quality cannot be guaranteed;

[0008] (2) It is only used as a passive zone reinforcement measure and cannot actively and dynamically adjust the strength and stress of the passive zone according to the deformation of the foundation pit, so the deformation control effect is limited.

[0009] Patent 2: A support system for actively controlling the displacement of a foundation pit and a design method thereof (publication number: CN108130910A, publication date: June 8, 2018).

[0010] The present application relates to the technical field of foundation pit engineering, and is a support system in a foundation pit, which comprises a retaining structure, an adjustable force adding device, a concrete transverse support system and a column system; the force adding device is transversely arranged and connected with the retaining structure and the concrete transverse support system at two ends; the force adding device is controlled by a control system to exert a transverse thrust on the retaining structure, so that the active control of the horizontal deformation of the retaining structure is realized. The present application has the advantages of active control of the displacement of the retaining structure and stability of the support system; the displacement of the retaining structure can be controlled by the force adding device, and the stability of the concrete support system is ensured; and the partitioning can be avoided during large-area excavation, and the cost and construction period are saved.

[0011] The patent has the following disadvantages:

[0012] (1) The active control of the deformation of the retaining structure is only realized by the transverse support above the pit bottom, so the deformation of the retaining structure in a certain range adjacent to the transverse support above the pit bottom can be controlled, but the deformation of the passive zone at the pit bottom cannot be controlled;

[0013] (2) The heave deformation of the soil at the pit bottom cannot be controlled, so the heave deformation of the pit bottom is large, which further causes the horizontal deformation of the deep retaining structure to be difficult to control and affects the surrounding environment.

[0014] In summary, the problem to be solved by the present application is:

[0015] 1) In the current foundation pit engineering construction process, when the foundation pit is excavated in a soft soil area, the soil below the pit bottom is prone to excessive deformation because the soil below the pit bottom has a low strength and a high sensitivity, the constraint effect of the upper soil is significantly weakened due to the excavation of the upper soil, the stress of the soil in the passive zone at the pit bottom is reduced, the resistance provided by the retaining structure is insufficient, and the soil below the pit bottom and the retaining structure are deformed too much, which further causes the deformation of the surrounding buildings and structures;

[0016] 2) There is a lack of equipment and methods for dynamically constraining the stress and deformation of the soil in the passive zone at the pit bottom in the current foundation pit engineering construction equipment, so it is difficult to inhibit the stress release, soil heave and horizontal resistance weakening of the passive zone at the pit bottom. SUMMARY

[0017] The present application aims to provide a passive zone pressure deformation active control device, system and method for a foundation pit, which can achieve good control effect on the upward deformation of the soil at the pit bottom (passive zone).

[0018] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution:

[0019] An active control device for pressure deformation in the passive zone of a foundation pit project is disclosed. The active control device includes a reaction pile, a counterpressure base plate, and a counterpressure control device. The reaction pile is installed in the soil at the bottom of the foundation pit. The counterpressure base plate covers the soil at the bottom of the foundation pit. The counterpressure control device includes a top force transmission structure and a loading device. The top force transmission structure is firmly connected to the reaction pile, and the loading device applies downward dynamic pressure to the counterpressure base plate based on the top force transmission structure.

[0020] Furthermore, the active pressure deformation control device includes one reaction pile, and the counter-pressure control device is equipped with two loading devices; the two loading devices are respectively placed on the symmetrical sides of the reaction pile, and the two loading devices apply downward dynamic pressure to the counter-pressure bottom plates on both sides of the reaction pile based on the top force transmission structure.

[0021] Furthermore, the active pressure deformation control device includes one reaction pile, and the counter-pressure control device includes one loading device; the active pressure deformation control device also includes a bottom force transmission structure, which spans above the upper end of the reaction pile, and the bottom force transmission structure is based on the counter-pressure base plates on both sides of the reaction pile; the loading device applies downward dynamic pressure to the counter-pressure base plates on both sides of the reaction pile based on the top force transmission structure and through the bottom force transmission structure.

[0022] Furthermore, the pressure deformation active control device includes two reaction piles, and the counter-pressure control device is equipped with one loading device; the top force transmission structure is firmly connected to the two reaction piles, the loading device is placed between the two reaction piles, and the loading device applies downward dynamic pressure to the counter-pressure base plate between the two reaction piles based on the top force transmission structure.

[0023] Furthermore, the counter-pressure base plate includes a structural layer and a horizontal drainage structure, wherein the horizontal drainage structure is made of a flexible permeable material and is located at the bottom of the structural layer.

[0024] Furthermore, for the counterweight base plate, a vertical drainage structure is provided in the soil at the bottom of the foundation pit, and the upper end of the vertical drainage structure is connected to the horizontal drainage structure of the counterweight base plate.

[0025] Furthermore, the top force transmission structure is firmly connected to the reaction pile by steel bars or anchor rods; there is a loading device accommodating space between the top force transmission structure and the counter-pressure base plate, and the loading device is installed in the loading device accommodating space.

[0026] Furthermore, the back pressure control device also includes a control host, and the loading device is controlled by the control host.

[0027] An active control system for pressure deformation in the passive zone of a foundation pit project, the active control system for pressure deformation includes a number of active control devices for pressure deformation as described above, these active control devices for pressure deformation are arranged in a zigzag pattern at the bottom of the foundation pit.

[0028] An active control method for pressure deformation in the passive zone of a foundation pit project is disclosed. This active control method employs the pressure deformation active control device described above. The active control method includes: 1) first constructing the retaining structure, engineering piles, reaction piles, and other foundation pit-related work; 2) excavating the earthwork to the design elevation of the counterpressure bottom slab and constructing the counterpressure bottom slab; 3) installing the counterpressure control device and connecting it to the reaction piles; 4) adjusting the downward pressure reaction force to control the stress and deformation of the passive zone of the retaining structure below the counterpressure bottom slab based on foundation pit monitoring data; 5) constructing the underground structure after the foundation pit meets the conditions for underground structure construction and dismantling the counterpressure control device.

[0029] The advantages of the pressure deformation active control device, system, and method of the present invention compared to the prior art are as follows:

[0030] 1) In the pressure deformation active control device, system and method of the present invention, dynamic pressure is applied to the soil based on the strong static force of the reaction pile, thereby achieving good control effect on the upward deformation of the soil at the bottom of the foundation pit (passive zone), effectively ensuring the stability of the surrounding retaining structure and surrounding building structure of the foundation pit, and ensuring the construction safety of the foundation pit project.

[0031] 2) The pressure deformation active control device of the present invention is a completely new design device compared with the prior art. It is a device specifically designed to provide dynamic constraints on soil pressure deformation in the passive zone at the bottom of the foundation pit, and provides a new equipment support for suppressing stress release, soil heave and weakening of horizontal resistance in the passive zone at the bottom of the foundation pit. Attached Figure Description

[0032] Figure 1 is a side view of the active pressure deformation control device based on Embodiment 1 of the present invention;

[0033] Figure 2 is a top view of the active pressure deformation control device based on Embodiment 1 of the present invention;

[0034] Figure 3 is a side view of the active pressure deformation control device based on Embodiment 2 of the present invention;

[0035] Figure 4 is a top view of the active pressure deformation control device based on Embodiment 2 of the present invention;

[0036] Figure 5 is a side view of the pressure deformation active control device based on Embodiment 3 of the present invention.

[0037] The diagram shows: 1. Reaction pile, 2. Counterpressure control device, 2-1. Loading device, 2-2. Top force transmission structure, 2-3. Control host, 2-4. Bottom force transmission structure, 3. Counterpressure base plate, 3-1. Structural layer, 3-2. Horizontal drainage structure, 3-3. Vertical drainage structure, 4. Pit bottom excavation face, 5. Retaining structure. Detailed Implementation

[0038] The following provides further details on specific embodiments of the present invention: Implementation

[0039] This embodiment 1 provides an active control device for pressure deformation in the passive zone of a foundation pit project. The function of this active control device is to apply a downward dynamic pressure force to the soil at the bottom of the foundation pit (passive zone) based on the reaction piles 1 in the foundation pit, so as to control the upward deformation force of the soil at the bottom of the foundation pit (passive zone) and thus avoid the upward displacement deformation of the soil at the bottom of the foundation pit (passive zone).

[0040] Referring to Figures 1 and 2, the active pressure deformation control device mainly includes: a reaction pile 1, a counter-pressure base plate 3, and a counter-pressure control device 2.

[0041] The reaction pile 1 is constructed in the form of a bored cast-in-place pile and installed in the soil at the bottom of the foundation pit. In other embodiments, the reaction pile 1 may also be in the form of a precast pile.

[0042] The reaction piles 1 are located within the excavation depth of the adjacent retaining structure 5 within the foundation pit. The bottom of the reaction pile 1 is below the bottom of the retaining piles of the retaining structure 5, and the top of the reaction pile 1 is above the excavation surface 4 at the bottom of the pit. A row of reaction piles 1 adjacent to the retaining structure 5 can utilize the main structural piles. It should be noted that the specific number of reaction piles 1 constructed in a foundation pit project can be determined according to the design requirements of the foundation pit project.

[0043] The counterweight base plate 3 covers the soil at the bottom of the foundation pit (passive zone). A through hole is provided on the counterweight base plate 3 for each reaction pile 1, allowing the upper end of the reaction pile 1 to protrude through the counterweight base plate 3 via the through hole. It should be noted that the reaction pile 1 is completely detached from the counterweight base plate 3.

[0044] It should be noted that reinforced concrete, steel, or precast structures with a certain thickness can be used as the counter-pressure base plate 3.

[0045] More specifically, the counterweight base plate 3 is composed of two layers: an upper structural layer 3-1 and a lower horizontal drainage structure 3-2. The structural layer 3-1 is made of reinforced concrete, and the horizontal drainage structure 3-2 is made of flexible permeable material and is installed at the bottom of the structural layer 3-1. The horizontal drainage structure 3-2 is attached to the soil at the bottom of the foundation pit.

[0046] It should be noted that in this embodiment 1, the counter-pressure bottom plate 3 is set within the excavation depth of the adjacent retaining structure 5 in the foundation pit, which is three times the excavation depth.

[0047] The counterpressure control device 2 is installed between the reaction pile 1 and the counterpressure base plate 3, specifically at the position where the upper end of the reaction pile 1 protrudes through the penetration hole in the counterpressure base plate 3. The function of this counterpressure control device 2 is to apply downward dynamic pressure to the counterpressure base plate 3 based on the reaction pile 1, thereby applying downward dynamic pressure to the soil at the bottom of the foundation pit (passive zone) through the counterpressure base plate 3. In this way, the upward deformation force at the bottom of the foundation pit (passive zone) is controlled by the strong stabilizing force of the reaction pile 1, thus preventing the soil at the bottom of the foundation pit from displacing and heaving upwards, and avoiding adverse consequences such as damage to the retaining structure 5 and surrounding building structures.

[0048] More specifically, the counter-pressure control device 2 includes a top force transmission structure 2-2 and a pair of loading devices 2-1 (which are hydraulic telescopic cylinders, commonly known as jacks).

[0049] The top force transmission structure 2-2 is made of steel and is firmly connected to the upper end of the reaction pile 1 by steel bars (or anchor rods). A certain space is maintained between the top force transmission structure 2-2 and the counter-pressure base plate 3. For ease of description, this space is defined as the "loading device accommodating space".

[0050] The pair of loading devices 2-1 are placed in the loading device accommodating space and are placed on the symmetrical sides of the reaction pile 1. The loading device 2-1 is placed vertically on the counter-pressure base plate 3. Its body (i.e., cylinder) is based on the counter-pressure base plate 3 through a sleeper, and its top support end abuts against the lower part of the top force transmission structure 2-2.

[0051] The two loading devices 2-1 simultaneously extend and support each other. In this way, the loading device 2-1 applies downward dynamic pressure to the counter-pressure base plate 3 based on the top force transmission structure 2-2. Since the top force transmission structure 2-2 is firmly connected to the reaction pile 1, the "downward dynamic pressure is applied to the counter-pressure base plate 3 based on the reaction pile 1" is thus realized.

[0052] To achieve dynamic control of the back pressure control device 2, a control host 2-3 is also provided for it. All loading devices 2-1 are connected to the control host 2-3 via dedicated control signal cables. Operators can control the loading devices 2-1 to output dynamic loading forces through the control host 2-3. In other words, the loading devices 2-1 are controlled by the control host 2-3, and the magnitude of the applied force can be controlled by adjusting the control parameters on the control host 2-3.

[0053] In this embodiment 1, the control host 2-3 adopts the existing hydraulic system intelligent control pump station. The control host 2-3 is connected to the loading device 2-1 through hydraulic pipelines. The loading device 2-1 can be controlled by dynamically adjusting the control parameters to control the magnitude of the downward pressure applied by the loading device 2-1.

[0054] The pressure deformation active control device of Embodiment 1 is a newly designed device used for:

[0055] Within the foundation pit, a downward dynamic compressive force is applied to the soil at the bottom of the pit (passive zone) to prevent soil heave and thus avoid deformation of the retaining structure 5 and surrounding building structures. Crucially, the pressure deformation active control device in this embodiment applies dynamic compressive force to the soil based on the strong stabilizing force of the reaction piles 1, achieving a good compressive effect and effectively ensuring the stability of the retaining structure 5 and surrounding building structures, thereby guaranteeing the construction safety of the foundation pit project.

[0056] In addition, the dynamic pressure applied to the soil at the bottom of the foundation pit (passive zone) can be dynamically controlled. The stress and deformation of the soil at the bottom of the foundation pit (passive zone) can be dynamically adjusted according to the deformation of the foundation pit and the surrounding environment, thereby dynamically controlling the deformation of the retaining structure 5 and significantly improving the deformation control capability of the retaining structure 5 after the foundation pit is excavated to the bottom.

[0057] The specific implementation process of using the pressure deformation active control device of Embodiment 1 to actively control pressure deformation in the passive zone is as follows:

[0058] 1. First, construct retaining piles, water-stop curtain, engineering piles, reaction piles 1, and foundation pit support structure, etc.

[0059] 2. Excavate the earthwork to the design elevation of the foundation pit, construct the structural layer 3-1 of the counterweight bottom slab 3 within a range of 3 times the excavation depth adjacent to the foundation pit, and construct the horizontal drainage structure 3-2, and reserve holes at the position of the reaction pile 1.

[0060] 3. Install loading device 2-1, top force transmission structure 2-2 and control host 2-3, and connect them to reaction pile 1 and counter-pressure base plate 3. Each loading device 2-1 applies a downward pressure of 1000kN.

[0061] 4. Based on the foundation pit monitoring data, the control host 2-3 of the counter-pressure control device 2 adjusts the downward pressure reaction force. When the deformation of the retaining structure 5 shows an increasing trend or when control is needed, the control host 2-3 increases the downward pressure applied by the loading device 2-1. When the deformation of the retaining structure 5 shows a decreasing trend, the downward pressure applied by the loading device 2-1 is maintained or decreased, thereby dynamically controlling the stress and deformation of the retaining structure 5.

[0062] 5. Once the foundation pit meets the conditions for underground structure construction, construct the underground structure and remove the counterpressure control device 2.

[0063] It should be noted that multiple active pressure deformation control devices are installed at the bottom of the foundation pit and combined into a system (all active pressure deformation control devices share the counter-pressure base plate 3). This system can be called an active pressure deformation control system for the passive zone of foundation pit engineering. In the active pressure deformation control system for the passive zone of foundation pit engineering, the counter-pressure control device 2 and the reaction pile 1 are arranged in no less than one row within the range of the counter-pressure base plate 3. Implementation

[0064] This embodiment 2 provides an active pressure deformation control device, whose basic concept is basically similar to that of the active pressure deformation control device in embodiment 1. Both devices achieve the function of "applying a downward dynamic pressure force to the soil at the bottom of the foundation pit (passive zone) based on the reaction piles 1 in the foundation pit".

[0065] Referring to Figures 3 and 4, the difference between the pressure deformation active control device of Embodiment 2 and Embodiment 1 is as follows:

[0066] 1) The number of loading devices 2-1 used in the back pressure control device 2 is one, that is, one loading device 2-1 is used to apply the loading force.

[0067] To achieve this effect, the upper end of the reaction pile 1 does not completely pass through the counter-pressure base plate 3, or in other words, the upper end of the reaction pile 1 is lower than the upper surface of the counter-pressure base plate 3, thereby creating conditions for the subsequent installation of the bottom force transmission structure 2-4.

[0068] The counterpressure control device 2 also includes a bottom force transmission structure 2-4, which spans across the upper end of the reaction pile 1 and is based on the counterpressure base plates 3 on both sides of the reaction pile 1. The loading device 2-1 is set based on the bottom force transmission structure 2-4. In this way, when the loading device 2-1 performs an extension and support action, the loading device 2-1 applies downward dynamic pressure to the counterpressure base plates 3 on both sides of the reaction pile 1 based on the top force transmission structure 2-2 and through the bottom force transmission structure 2-4, thus realizing "applying downward dynamic pressure to the counterpressure base plates 3 based on the reaction pile 1".

[0069] 2) Regarding the horizontal drainage structure 3-2 of the counterweight base 3, numerous vertical drainage structures 3-3 are installed in the soil at the bottom of the foundation pit. The upper ends of these vertical drainage structures 3-3 are connected to the horizontal drainage structure 3-2 of the counterweight base 3, and these counterweight base 3 extend downwards to a certain depth. These vertical drainage structures 3-3 are made of flexible or rigid permeable materials, and their function is to discharge vertically drained water through the horizontal drainage structure 3-2 to the outside of the counterweight base 3.

[0070] 3) Referring to Figure 3, when multiple pressure deformation active control devices are set up at the bottom of the foundation pit and combined into a system, the reaction piles 1 and the counterpressure control devices 2 of these pressure deformation active control devices are arranged in a zigzag pattern at the bottom of the pit.

[0071] In this embodiment 2, the purpose of adjusting the structure and arrangement of the counterpressure control device 2 is to adapt to the pressure control requirements of the pit bottom (passive zone) due to changes in the excavation depth. At the same time, the structure of the counterpressure bottom plate 3 is adjusted to adapt to different soil layers in the pit, so as to increase the applicability and economy of the pressure deformation active control device. Implementation

[0072] This embodiment 3 provides an active pressure deformation control device, whose basic concept is similar to that of the active pressure deformation control devices in embodiments 1 and 2. Both devices achieve the function of "applying a downward dynamic pressure force to the soil at the bottom of the foundation pit (passive zone) based on the reaction piles 1 in the foundation pit".

[0073] Referring to Figure 5, the difference between the pressure deformation active control device of Embodiment 3 and Embodiments 1 and 2 is that:

[0074] 1) Instead of setting up a dedicated counterpressure control device 2 for each reaction pile 1, a counterpressure control device 2 is set up for every two reaction piles 1.

[0075] More specifically, the pressure deformation active control device includes two reaction piles 1 and a counter-pressure control device 2.

[0076] The counterpressure control device 2 includes a top force transmission structure 2-2 and a loading device 2-1. The top force transmission structure 2-2 is firmly connected to two reaction piles 1 by steel bars, and the loading device 2-1 is placed between the two reaction piles 1. The loading device 2-1 can apply downward dynamic pressure to the counterpressure base plate 3 between the two reaction piles 1 based on the top force transmission structure 2-2, thereby achieving the effect of "applying downward dynamic pressure to the counterpressure base plate 3 based on the reaction piles 1".

[0077] 2) The counter-pressure base plate 3 only includes the structural layer 3-1, and no horizontal drainage structure 3-2 is set.

[0078] In this embodiment 3, the requirement of the foundation pit bottom (passive zone) pressure control, the structure of the counter-pressure control device 2 and the counter-pressure bottom plate 3 are adjusted to optimize the economy of the pressure deformation active control device.

[0079] The above merely describes the preferred embodiments of the present application, but should not be used to limit the protection scope of the present application, and therefore, any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A device for active control of pressure deformation in a passive zone of a foundation pit engineering, characterized in that: The active pressure deformation control device includes a reaction pile (1), a counter-pressure base plate (3), and a counter-pressure control device (2). The reaction pile (1) is set in the soil at the bottom of the foundation pit; The counterweight base plate (3) covers the soil at the bottom of the foundation pit; The counter-pressure control device (2) includes a top force transmission structure (2-2) and a loading device (2-1). The top force transmission structure (2-2) is firmly connected to the reaction pile (1), and the loading device (2-1) applies downward dynamic pressure to the counter-pressure base plate (3) based on the top force transmission structure (2-2).

2. The active control device for pressure deformation in the passive zone of foundation pit engineering according to claim 1, characterized in that: The active pressure deformation control device includes one reaction pile (1), and the counter-pressure control device (2) is equipped with two loading devices (2-1); Two loading devices (2-1) are placed on the symmetrical sides of the reaction pile (1). The two loading devices (2-1) apply downward dynamic pressure to the counter-pressure bottom plate (3) on both sides of the reaction pile (1) based on the top force transmission structure (2-2).

3. The active control device for pressure deformation in the passive zone of foundation pit engineering according to claim 1, characterized in that: The active pressure deformation control device includes one reaction pile (1), and the counter-pressure control device (2) is equipped with one loading device (2-1); The pressure deformation active control device also includes a bottom force transmission structure (2-4), which spans across the upper end of the reaction pile (1) and is based on the counter-pressure bottom plates (3) on both sides of the reaction pile (1). The loading device (2-1) applies downward dynamic pressure to the counter-pressure base plates (3) on both sides of the reaction pile (1) based on the top force transmission structure (2-2) and through the bottom force transmission structure (2-4).

4. The active control device for pressure deformation in the passive zone of foundation pit engineering according to claim 1, characterized in that: The active pressure deformation control device includes two reaction piles (1), and the counter-pressure control device (2) is equipped with one loading device (2-1); The top force transmission structure (2-2) is simultaneously and firmly connected to the two reaction piles (1). The loading device (2-1) is placed between the two reaction piles (1). The loading device (2-1) applies downward dynamic pressure to the counter-pressure base plate (3) between the two reaction piles (1) based on the top force transmission structure (2-2).

5. The active control device for pressure deformation in the passive zone of foundation pit engineering according to claim 1, characterized in that: The counter-pressure base plate (3) includes a structural layer (3-1) and a horizontal drainage structure (3-2). The horizontal drainage structure (3-2) is made of flexible permeable material and is located at the bottom of the structural layer (3-1).

6. The foundation engineering passive area pressure deformation active control device according to claim 5, characterized in that: For the counterweight base plate (3), a vertical drainage structure (3-3) is set in the soil at the bottom of the foundation pit, and the upper end of the vertical drainage structure (3-3) is connected to the horizontal drainage structure (3-2) of the counterweight base plate (3).

7. The foundation engineering passive area pressure deformation active control device according to claim 1, characterized in that: The top force transmission structure (2-2) is firmly connected to the reaction pile (1) by steel bars or anchor rods; There is a loading device accommodating space between the top force transmission structure (2-2) and the counter-pressure base plate (3), and the loading device (2-1) is placed in the loading device accommodating space.

8. The foundation engineering passive area pressure deformation active control device according to claim 1, characterized in that: The back pressure control device (2) also includes a control host (2-3), and the loading device (2-1) is controlled by the control host (2-3).

9. A foundation pit engineering passive zone pressure deformation active control system, characterized in that: The pressure deformation active control system includes a number of pressure deformation active control devices as described in claim 1, which are arranged in a zigzag pattern at the bottom of the foundation pit.

10. A method for actively controlling pressure deformation in the passive zone of a foundation pit project, wherein the method employs the active pressure deformation control device as described in claim 1, characterized in that: The active pressure deformation control method includes: 1) First, construct the retaining structure (5), engineering piles, reaction piles (1), and other foundation pit engineering related work; 2) Excavate the earthwork to the design elevation of the counterweight base plate (3) and construct the counterweight base plate (3); 3) Install the counter-pressure control device (2) and connect it to the reaction pile (1); 4) Based on the foundation pit monitoring data, adjust the downward pressure reaction force to control the stress and deformation of the passive zone of the counter-pressure bottom plate (3) and the lower retaining structure (5); 5) After the foundation pit meets the conditions for underground structure construction, construct the underground structure and remove the counterpressure control device (2).

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