Foundation pit siphon recharge structure and construction and use method

Abstract

The invention discloses a foundation pit siphon recharge structure and a construction and use method, and belongs to the field of building construction foundation engineering. The structure comprises a water collecting well, a plurality of recharge wells, a siphon pipe net, a water supply system and a control system. The recharge wells are arranged on one side of the water collecting well or evenly distributed on the two sides of the water collecting well. A siphon main pipe in the siphon net is laid on the ground, one end of the siphon main pipe is arranged in an inner cavity of the water collecting well, the other end of the siphon main pipe extends outwards in the arrangement direction of the recharge well to form a closed end, and the closed end is provided with an exhaust port. Siphon branch pipes leading to inner cavities of all the recharge wells are vertically arranged on the siphon main pipe, and starting valves are arranged on the siphon branch pipes. A water seal device for ensuring continuous siphon operation is arranged at the end, located in the inner cavity of the recharge well, of the siphon branch pipe. And the water supply system provides recharge water for the water collecting well. The control system receives water level information from the water collecting well and the recharge well and controls the water supply system to be opened or closed. The recharge water flow is dynamically adjusted by adjusting the water level difference in the water collecting well and the recharge well.

Description

Technical Field

[0001] The present invention belongs to the field of building construction foundation engineering, and in particular relates to a foundation pit siphon recharge structure and a construction and use method. Background Art

[0002] When constructing foundation pits in areas with abundant groundwater, dewatering is often necessary. However, dewatering can have a wide-ranging impact, causing not only a drop in the water level within the pit but also a decrease in the surrounding groundwater level. This drop in water level often leads to a series of serious engineering problems, such as ground subsidence, road collapses, building cracks, and groundwater pipeline severance, posing threats to surrounding infrastructure and building safety.

[0003] When there are important pipelines or buildings near a foundation pit, recharge wells are often required to prevent the adverse effects of falling water levels on these areas. The purpose of a recharge well is to recharge a certain amount of groundwater into the surrounding area of ​​the foundation pit, thereby maintaining the water level in the protected area and preventing it from dropping excessively. In this case, water level control becomes the core of foundation pit recharge technology. If the recharge volume is too large, the water level in the foundation pit may not be effectively lowered, thus affecting the construction progress. If the recharge volume is too small, the water level drop in the protected area cannot be effectively controlled, and the desired protection effect cannot be achieved.

[0004] Currently, conventional recharge technologies typically require a separate water level switch for each recharge well to control the water level. This control method is very cumbersome to operate. Therefore, developing a foundation pit recharge technology with more convenient and accurate water level control is of great practical significance for improving construction efficiency, ensuring the safety of the surrounding environment, and reducing the occurrence of engineering accidents. Summary of the Invention

[0005] The purpose of the present invention is to solve the problem of troublesome control of foundation pit recharge water level in the prior art, and to provide a foundation pit siphon recharge structure and a construction and use method.

[0006] The specific technical solutions adopted in the present invention are as follows:

[0007] In a first aspect, the present invention provides a foundation pit siphon recharge structure, comprising a water collection well, a plurality of recharge wells, a siphon pipe network, a water supply system, and a control system; the water collection well and the recharge well are arranged around a protected area outside the foundation pit; the plurality of recharge wells are arranged on one side of the water collection well or evenly distributed on both sides of the water collection well;

[0008] The siphon pipe network includes a siphon main pipe and a plurality of siphon branches; the siphon main pipe is laid on the ground, one end of the siphon main pipe is arranged in the inner cavity of the water collection well, and the other end extends outward along the arrangement direction of the recharge well and is closed; an exhaust port is provided at the closed end of the siphon main pipe; siphon branches are provided on the side wall of the siphon main pipe, leading to the inner cavity of each recharge well; a starting valve is provided at the connection between each siphon branch pipe and the siphon main pipe; a water seal device is provided at the end of the siphon branch pipe located in the inner cavity of the recharge well to prevent air from entering;

[0009] The water supply system provides recharge water to the water collection well; the control system receives water level information from the water collection well and the recharge well, controls the opening or closing of the water supply system; and dynamically adjusts the recharge water flow by adjusting the water level difference between the water collection well and the recharge well.

[0010] Preferably, the water collection well is divided into an upper water collection pit and a lower water collection well pipe, and the cross-section of the water collection well pipe is smaller than the cross-section of the water collection pit.

[0011] Preferably, the diameter of the recharge well is 100-300 mm.

[0012] Preferably, the diameter of the siphon branch pipe is 16-32 mm, and the diameter of the siphon main pipe is larger than the diameter of the siphon branch pipe.

[0013] Preferably, one end of the siphon main pipe located in the inner cavity of the water collection well is set at least 1m below the lowest design water level of the water collection well.

[0014] Preferably, the water supply system includes a recharge water tank for storing recharge water and a water pump for transporting the recharge water; the recharge water is tap water or treated groundwater pumped out from foundation pit precipitation.

[0015] Preferably, the control system includes an intelligent control unit, a recharge well water level sensor and a water collection well water level sensor; the intelligent control unit receives water level information from the recharge well water level sensor and the water collection well water level sensor, and controls the water supply system.

[0016] Furthermore, a water level sensor for the water collection well is provided at the water level control position in the inner cavity of the water collection well; and a water level sensor for the recharge well is provided at the water level control position in the inner cavity of each recharge well.

[0017] In a second aspect, the present invention provides a construction and use method using the foundation pit siphon recharge structure described in the first aspect, the specific steps of which are as follows:

[0018] S1: According to the design drawings, a water collection well and several recharging wells are set up outside the foundation pit;

[0019] S2: Siphon main pipes are laid along the distribution of the recharge wells. One end of the siphon main pipe is located at least 1m below the lowest design water level in the water collection well cavity. The other end extends outward along the distribution of the recharge wells and is a closed end with an exhaust port. A siphon branch pipe is vertically installed in the cavity of each recharge well, and the other end is connected to the siphon main pipe through a tee connector.

[0020] S3: Install a recharge water tank and a water pump, and connect the recharge water tank to the water collection well through pipes and water pumps; install a water collection well water level sensor at the water level control position in the water collection well cavity, and install a recharge well water level sensor at each recharge well cavity water level control position; connect the water collection well water level sensor and the recharge well water level sensor to the intelligent control unit via a data cable;

[0021] S4: Introduce tap water or filtered groundwater into the recharge tank as recharge water;

[0022] S5: After the sealing test, the foundation pit siphon recharge structure is degassing and starting: first, close the starting valve on each siphon branch pipe, start the water pump, and inject recharge water into the water collection well until the water level in the water collection well is higher than the elevation of the siphon main pipe; then open the exhaust port on the siphon main pipe, ensure that the siphon main pipe is filled with water, and then close the exhaust port; then open the starting valve on the siphon branch pipe closest to the water collection well, inject water into the siphon branch pipe, and then close the starting valve; complete the water injection and exhaust of all siphon branches in sequence;

[0023] S6: After the exhaust is completed, the start valve on the siphon branch is reopened to start siphon recharge. Recharge water is injected into the water collection well through a water pump. Under the action of the siphon, the recharge water enters the recharge well through the siphon main pipe and the siphon branch, and then recharges into the surrounding soil layer to replenish the water level drop caused by the pumping of water from the dewatering well. When the recharge water level changes, the foundation pit siphon dewatering structure automatically adjusts the water pressure difference between the water collection well and the recharge well, dynamically adjusts the recharge flow rate, and accurately controls the recharge water level within the design range to ensure the stability of the surrounding soil level during foundation pit dewatering.

[0024] S7: After the foundation pit dewatering is completed, stop the siphon recharge; recycle the materials, and seal the water collection well and recharge well.

[0025] Preferably, the dynamic adjustment in step S6 is as follows:

[0026] Open the start valves on the siphon branches in sequence, and at the same time start the water pump to inject recharge water into the water collection well to increase the water pressure difference between the water collection well and the recharge well;

[0027] If the water level in the recharge well reaches the maximum control level, the intelligent control unit receives water level information from the recharge well water level sensor and shuts down the water pump. The water level difference between the water collection well and the recharge well decreases, and the flow rate recharged to the surrounding soil layer decreases, and the water level in the recharge well also drops.

[0028] If the water level in the recharge well reaches the minimum control water level, the intelligent control unit receives the water level information from the recharge well water level sensor and starts the water pump; the water level difference between the collection well and the recharge well becomes larger, the flow rate recharged to the surrounding soil layer increases accordingly, and the water level in the recharge well also rises accordingly.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] (1) The water level of the foundation pit siphon recharge structure provided by the present invention is uniformly controlled and dynamically adjusted, which can effectively protect the environment around the foundation pit.

[0031] The foundation pit siphon recharge structure connects each recharge well through a siphon official website, so that the water level remains basically consistent, which is convenient for unified control. The siphon flow rate is related to the water level difference between the recharge well and the water collection well: when the water level in the recharge well decreases, the water level difference increases and the siphon flow rate increases; conversely, the siphon flow rate decreases. This dynamic adjustment mechanism can effectively control the recharge water level within the set range to ensure a good water level control effect. In addition, the structural siphon recharge effect provided by the present invention is significant, and can effectively prevent the water level from dropping due to foundation pit dewatering, thereby avoiding accidents such as road collapse, building settlement, and pipeline breakage caused by water level drop, providing strong protection for the environment around the foundation pit, and reducing engineering risks caused by foundation pit dewatering.

[0032] (2) The foundation pit siphon recharge structure provided by the present invention is simple and easy to operate.

[0033] The components of the foundation pit siphon recharge system are simple in design and can be assembled using conventional materials and equipment. Furthermore, the system is easily activated by automatically flowing water into the siphon pipes, using a water level higher than the siphon pipes. Filling and exhausting each pipe individually completes the siphon pipe network, eliminating the need for complex equipment or large water flows. During operation, the system automatically adjusts flow based on the water level, eliminating the need for manual intervention and making water level adjustment easy, greatly enhancing operational convenience. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Schematic diagram of the foundation pit siphon recharge structure provided in Example 1;

[0035] Figure 2 A schematic plan view of the foundation pit siphon recharge structure provided in Example 1;

[0036] Figure 3 A schematic plan view of the foundation pit siphon recharge structure provided in Example 2;

[0037] Figure 4 A cross-sectional view of a water collection well provided by the present invention;

[0038] Figure 5 A schematic diagram of a water seal device provided by the present invention;

[0039] Figure 6 A schematic diagram of the startup of the foundation pit siphon recharge structure provided in Example 3;

[0040] In the figure: water collection well 1, water collection well pipe 11, water collection pit 12, recharge well 2, siphon pipe network 3, siphon main pipe 31, exhaust port 311, start valve 321, siphon branch pipe 32, water seal device 322, water supply system 4, recharge water tank 41, water pump 42, intelligent control unit 51, recharge well water level sensor 521, water collection well water level sensor 522. DETAILED DESCRIPTION

[0041] The present invention will be further described and illustrated below with reference to the accompanying drawings and specific embodiments. The technical features of each embodiment of the present invention may be combined accordingly, provided that there is no conflict between them.

[0042] Example 1

[0043] like Figure 1 and Figure 2 As shown, this embodiment provides a foundation pit siphon recharge structure in which a recharge well is arranged on one side of a water collection well, as follows.

[0044] The foundation pit siphon recharge structure provided in this embodiment includes a water collection well 1, several recharge wells 2, a siphon pipe network 3, a water supply system 4 and a control system; the water collection well 1 and recharge well 2 are arranged around the protected area outside the foundation pit. Figure 2 As shown, the recharge wells 2 are spaced apart and arranged on one side of the water collection well 1. The diameter of the recharge well 2 is smaller than that of the water collection well 1, and the recharge well 2 is generally set to 100-300 mm. This embodiment adopts a water collection well 1 with a variable cross-section, specifically as shown in FIG. Figure 4 As shown, the water collection well 1 is divided into an upper water collection pit 12 and a lower water collection well pipe 11, and the cross section of the water collection well pipe 11 is smaller than that of the water collection pit 12.

[0045] It should be noted that the water collection well 1 can have either a uniform cross-section or a variable cross-section with a larger top and smaller bottom. However, a variable cross-section is preferred. This is because the key location in the water collection well that affects the recharge effect is the pipe section where the water level changes, usually located at the top of the well pipe. Using a variable cross-section with a larger top and smaller bottom can reduce the fluctuation range of the recharge water level, ensure a stable water level in the recharge well, save materials, and reduce construction costs.

[0046] The siphon pipe network 3 includes a siphon main pipe 31 and a plurality of siphon branches 32. In this embodiment, the diameter of the siphon branches 32 is 16 to 32 mm, and the diameter of the siphon main pipe 31 is larger than the diameter of the siphon branches 32. Those skilled in the art can select appropriate sizes of the siphon main pipe 31 and the siphon branches 32 according to actual working conditions.

[0047] The siphon main pipe 31 is laid on the ground, and one end of the siphon main pipe 31 is arranged in the inner cavity of the water collection well 1, and the end is arranged at least 1m below the lowest design water level of the water collection well 1. The other end of the siphon main pipe 31 extends outward along the arrangement direction of the recharge well 2 and is closed, and an exhaust port 311 is arranged near the closed end. A siphon branch pipe 32 is arranged on the side wall of the siphon main pipe 31, and the siphon branch pipe 32 is vertically arranged to lead to the inner cavity of each recharge well 2. One end of the siphon main pipe 31 and the siphon branch pipe 32 are connected by a tee. The other end of the siphon branch pipe 32 is vertically inserted into the inner cavity of each recharge well 2. A start valve 321 for controlling the start of the recharge well is provided at the connection between each siphon branch pipe 32 and the siphon main pipe 31.

[0048] like Figure 5 As shown, a water seal device 322 is installed at the end of the siphon branch pipe 32 located within the inner cavity of the recharging well 2 to ensure normal siphon operation and prevent air ingress. The water seal device 322 is an open water storage container fixed to the end of the siphon branch pipe 32. It ensures that the end of the siphon branch pipe 32 is always underwater. When the water level in the recharging well 2 is low and water injection is started and stopped, the water column in the siphon branch pipe 32 can be maintained. During the recharging process, the siphon will not be disrupted by air ingress due to the siphon branch pipe 32 being exposed to the water surface.

[0049] In this embodiment, a water supply system 4 provides recharge water to the water collection well 1. The water supply system 4 includes a recharge water tank 41 for storing the recharge water and a water pump 42 for transporting the recharge water. The recharge water can be tap water or filtered groundwater extracted from foundation pit dewatering. The recharge water quality must be no less than that of the groundwater from the recharged aquifer.

[0050] In this embodiment, the control system includes an intelligent control unit 51, a recharge well water level sensor 521, and a water collection well water level sensor 522. Several water collection well water level sensors 522 are spaced apart at the water level control position within the inner cavity of the water collection well 1; and several water collection well water level sensors 521 are spaced apart at the inner cavity of each recharge well 2. The intelligent control unit 51 receives water level information from the recharge well water level sensors 521 and the water collection well water level sensors 522 to control the on / off state of the water pump 42 in the water supply system 4.

[0051] Example 2

[0052] like Figure 3As shown, this embodiment provides a foundation pit siphon recharge structure in which recharge wells are evenly distributed on both sides of a water collection well, as follows.

[0053] The foundation pit siphon recharge structure provided in this embodiment includes a water collection well 1, several recharge wells 2, a siphon pipe network 3, a water supply system 4 and a control system; the water collection well 1 and recharge well 2 are arranged around the protected area outside the foundation pit. Figure 3 As shown, the recharge wells 2 are spaced apart on both sides of the water collection well 1. The rest of the arrangement is the same as in Example 1.

[0054] It should be noted that there are two possible distribution patterns for recharge wells and collection wells: one is to evenly distribute the recharge wells on both sides of the collection well, and the other is to concentrate the recharge wells on one side of the collection well. Evenly distributing the recharge wells on both sides of the collection well is the preferred method. This distribution shortens the flow path within the siphon network, minimizing head loss, thereby improving recharge efficiency and increasing recharge flow rates.

[0055] Example 3

[0056] In recharge technology, water level control is crucial. Neither excessive recharge, which would affect the dewatering of the foundation pit, nor insufficient recharge, which would effectively prevent the water level drop in the protected area. To address this issue, the foundation pit siphon recharge structure and method provided by the present invention ensure that the groundwater level remains within a controlled range.

[0057] Specifically, this embodiment provides a construction and use method using the foundation pit siphon recharge structure described in Example 2, and the steps are as follows:

[0058] Step 1: Drilling a well

[0059] Before the foundation pit is dewatered, a water collection well 1 and several recharge wells 2 are set up outside the foundation pit according to the design drawings. The recharge wells 2 are constructed using conventional well construction methods. Due to the small diameter of the recharge wells, they can be constructed using methods such as water flushing and handheld drilling. For the construction of a water collection well 1 with a variable cross-section, the appropriate construction method must be selected based on its cross-sectional form. For example, a water collection pit can be dug at the top, and then a well can be constructed at the bottom of the pit using conventional well construction methods. The water collection pit is then raised to the designed height above the ground. After the well is completed, well washing operations must be carried out to ensure smooth water flow from the recharge well.

[0060] Step 2: Arrange the siphon network

[0061] Siphon main pipes 31 are laid along the distribution of recharge wells 2. One end of the siphon main pipe 31 is located at least 1 meter below the lowest designed water level in the water collection well 1. The other end extends outward along the distribution of recharge wells 2 and is closed with a vent 311. A siphon branch pipe 32 is installed vertically in the cavity of each recharge well 2, and the other end is connected to the siphon main pipe 31 through a tee connector. Siphon pipes at the ground level are equipped with external protective devices to prevent the pipes from being crushed or damaged.

[0062] Step 3: Install water supply system and control system

[0063] Install a recharge water tank 41 and a water pump 42, and connect the recharge water tank 41 to the water collection well 1 through a pipe and the water pump 42; set a water collection well water level sensor 522 at the water level control position in the inner cavity of the water collection well 1, and set a recharge well water level sensor 521 at the water level control position in the inner cavity of each recharge well 2; the water collection well water level sensor 522 and the recharge well water level sensor 521 are connected to the intelligent control unit 51 via a data cable.

[0064] Step 4: Introduce recharge water

[0065] Tap water or filtered groundwater is introduced into the recharge water tank 41 as recharge water. It should be noted that when using groundwater extracted from a precipitation well as recharge water, the extracted groundwater should be filtered first to ensure that the water quality of the recharge water is not lower than that of the recharged aquifer groundwater.

[0066] Step 5: Exhaust Treatment

[0067] After the construction of the aforementioned foundation pit siphon recharge structure is completed, a leak test is conducted, followed by exhaust treatment. Because the ports of the siphon network are located underground, it is not convenient to directly inject water with a high-flow pump. If normal water flow is used for injection, water will easily flow out of the various branch ports, making it impossible to fully exhaust the gas. Therefore, the present invention adopts a step-by-step water injection method.

[0068] First, close the starting valve 321 on each siphon branch pipe 32, start the water pump 42, and inject recharge water into the water collection well 1 until the water level in the water collection well 1 is higher than the elevation of the siphon main pipe 31; then open the exhaust port 311 on the siphon main pipe 31, ensure that the siphon main pipe 31 is filled with recharge water, and then close the exhaust port 311; then open the starting valve 321 on the siphon branch pipe 32 closest to the water collection well 1, inject recharge water into the siphon branch pipe 32, and close the starting valve 321 after venting; complete the water injection and venting of all siphon branches 32 in sequence, and then close the water pump 42 to ensure that the water level in the water collection well 1 is higher than the water level in the recharge well 2.

[0069] After the water pump 42 is turned off and the water injection is stopped, the water seal device at the end of the siphon branch pipe 32 ensures that the siphon branch pipe 32 port is always underwater to prevent air from entering. Under the action of external atmospheric pressure, the water column in the branch pipe can be as high as 10m without flowing out.

[0070] Step 6: Dynamically adjust the water level

[0071] After all siphon branches 32 are filled with water and exhausted, siphon recharge is performed. The intelligent control unit 51 controls the opening or closing of the water pump 42, dynamically adjusting the water pressure difference between the water collection well 1 and the recharge well 2. Through the siphon effect, the recharge water enters the recharge well 2 through the siphon main pipe 31 and the siphon branch pipe 32, and is then recharged into the surrounding soil layer to replenish the water level drop caused by the dewatering well. The foundation pit siphon recharge structure adjusts the recharge flow rate according to the changes in the groundwater level, regulating the groundwater level to ensure the stability of the foundation pit dewatering and the surrounding soil level: when the groundwater level increases, the water level difference between the recharge well 2 and the water collection well 1 decreases accordingly, and the recharge flow rate decreases; conversely, when the groundwater level decreases, the water level difference between the recharge well 2 and the water collection well 1 increases accordingly, and the recharge flow rate also increases.

[0072] The intelligent control unit 51 is used to control the water level of the recharge well. The intelligent control unit 51 controls the start and stop of the water pump, adjusts the water pressure difference between the water collection well and the recharge well, thereby regulating the recharge flow rate, accurately controlling the recharge water level within the design range, and maintaining dynamic stability. The specific operations are as follows:

[0073] The start valves 321 on the siphon branch pipes 32 are opened in sequence, and the water pump 42 is started to inject recharge water into the water collection well 1, thereby increasing the water pressure difference between the water collection well 1 and the recharge well 2;

[0074] If the water level in the recharge well 2 reaches the maximum control water level, the intelligent control unit 51 receives the water level information from the recharge well water level sensor 521 and turns off the water pump 42; the water level difference between the water collection well 1 and the recharge well 2 becomes smaller, the flow rate recharged to the surrounding soil layer decreases, and the water level in the recharge well 2 also drops.

[0075] If the water level in recharge well 2 reaches the minimum control level, the intelligent control unit 51 receives water level information from the recharge well water level sensor 521 and turns on the water pump 42. The water level difference between the water collection well 1 and the recharge well 2 increases, and the flow rate recharged into the surrounding soil increases, and the water level in the recharge well 2 also rises accordingly. This process repeats to maintain the dynamic balance of the siphon recharge water level.

[0076] Step 7: After the foundation pit dewatering is completed, stop the siphon recharge; recycle the materials, and seal the water collection well 1 and the recharge well 2.

[0077] The embodiment described above is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Persons skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, any technical solution obtained by equivalent substitution or equivalent transformation falls within the scope of protection of the present invention.

Claims

1. A foundation pit siphon recharge structure, characterized in that: The system comprises a water collection well (1), a plurality of recharge wells (2), a siphon pipe network (3), a water supply system (4) and a control system; the water collection well (1) and the recharge well (2) are arranged around the protected area outside the foundation pit; the plurality of recharge wells (2) are arranged on one side of the water collection well (1) or evenly distributed on both sides of the water collection well (1); The siphon pipe network (3) comprises a siphon main pipe (31) and a plurality of siphon branches (32); the siphon main pipe (31) is laid on the ground, one end of the siphon main pipe (31) is arranged in the inner cavity of the water collection well (1), and the other end extends outward along the arrangement direction of the recharge well (2) and is closed; an exhaust port (311) is provided at the closed end of the siphon main pipe (31); siphon branches (32) leading to the inner cavity of each recharge well (2) are provided on the side wall of the siphon main pipe (31); a starting valve (321) is provided at the connection between each siphon branch pipe (32) and the siphon main pipe (31); a water seal device (322) for preventing air from entering is provided at the end of the siphon branch pipe (32) located in the inner cavity of the recharge well (2); The water supply system (4) provides reinjection water to the water collection well (1); the control system receives water level information from the water collection well (1) and the reinjection well (2) to control the opening or closing of the water supply system (4); and dynamically adjusts the reinjection water flow rate by adjusting the water level difference between the water collection well (1) and the reinjection well (2).

2. The foundation pit siphon recharge structure according to claim 1, characterized in that: The water collection well (1) is divided into an upper water collection pit (12) and a lower water collection well pipe (11), and the cross section of the water collection well pipe (11) is smaller than the cross section of the water collection pit (12).

3. The foundation pit siphon recharge structure according to claim 1, characterized in that: The diameter of the recharge well (2) is 100-300 mm.

4. The foundation pit siphon recharge structure according to claim 1, characterized in that: The diameter of the siphon branch pipe (32) is 16-32 mm, and the diameter of the siphon main pipe (31) is larger than the diameter of the siphon branch pipe (32).

5. The foundation pit siphon recharge structure according to claim 1, characterized in that: One end of the siphon main pipe (31) located in the inner cavity of the water collection well (1) is arranged at least 1 m below the lowest design water level of the water collection well (1).

6. The foundation pit siphon recharge structure according to claim 1, characterized in that: The water supply system (4) comprises a recharge water tank (41) for storing recharge water and a water pump (42) for conveying the recharge water; the recharge water is tap water or treated groundwater pumped out from foundation pit dewatering.

7. The foundation pit siphon recharge structure according to claim 1, characterized in that: The control system comprises an intelligent control unit (51), a recharge well water level sensor (521) and a water collection well water level sensor (522); the intelligent control unit (51) receives water level information from the recharge well water level sensor (521) and the water collection well water level sensor (522), and controls the water supply system (4).

8. The foundation pit siphon recharge structure according to claim 7, characterized in that: A water level sensor (522) is provided at a water level control position in the inner cavity of the water collection well (1); and a recharging well water level sensor (521) is provided at a water level control position in the inner cavity of each recharging well (2).

9. A construction method using the foundation pit siphon recharge structure according to any one of claims 1 to 8, characterized in that: The specific steps are as follows: S1: According to the design drawings, a water collection well (1) and several recharging wells (2) are set outside the foundation pit; S2: a siphon main pipe (31) is laid along the distribution position of the recharge well (2), one end of the siphon main pipe (31) is located at least 1m below the lowest design water level of the inner cavity of the water collection well (1), and the other end extends outward along the distribution position of the recharge well (2), and the other end is a closed end provided with an exhaust port (311); a siphon branch pipe (32) is vertically provided in the inner cavity of each recharge well (2), and the other end is connected to the siphon main pipe (31) through a three-way connector; S3: Installing a recharge water tank (41) and a water pump (42), connecting the recharge water tank (41) to the water collection well (1) through a pipe and the water pump (42); setting a water collection well water level sensor (522) at a water level control position in the inner cavity of the water collection well (1), and setting a recharge well water level sensor (521) at a water level control position in the inner cavity of each recharge well (2); connecting the water collection well water level sensor (522) and the recharge well water level sensor (521) to the intelligent control unit (51) via a data line; S4: introducing tap water or filtered groundwater into the recharge water tank (41) as recharge water; S5: After the sealing test, the foundation pit siphon recharge structure is then degassing and started: first, the starting valve (321) on each siphon branch pipe (32) is closed, the water pump (42) is started, and recharge water is injected into the water collection well (1) until the water level in the water collection well (1) is higher than the elevation of the siphon main pipe (31); then, the exhaust port (311) on the siphon main pipe (31) is opened, and the exhaust port (311) is closed after ensuring that the siphon main pipe (31) is filled with water; then, the starting valve (321) on the siphon branch pipe (32) closest to the water collection well (1) is opened, and after water is injected into the siphon branch pipe (32) and exhaust is exhausted, the starting valve (321) is closed; and the water injection and exhaust of all the siphon branches (32) are completed in sequence; S6: After the exhaust is completed, the start valve (321) on the siphon branch is reopened to perform siphon recharge; recharge water is injected into the water collection well (1) through the water pump (42); under the action of the siphon, the recharge water enters the recharge well (2) through the siphon main pipe (31) and the siphon branch pipe (32), and then recharged into the surrounding soil layer to supplement the water level drop caused by the water pumping from the dewatering well; when the recharge water level changes, the foundation pit siphon dewatering structure automatically adjusts the water pressure difference between the water collection well (1) and the recharge well (2), dynamically adjusts the recharge flow rate, and accurately controls the recharge water level within the design range, ensuring that the water level of the surrounding soil layer is stable during the foundation pit dewatering; S7: After the foundation pit dewatering is completed, the siphon recharge is stopped; the materials are recovered, and the water collection well (1) and the recharge well (2) are sealed.

10. The construction and use method of the foundation pit siphon recharge structure according to claim 9 is characterized in that: The dynamic adjustment in step S6 is specifically as follows: The start valves (321) on the siphon branch pipes (32) are opened in sequence, and the water pump (42) is simultaneously turned on to inject recharge water into the water collection well (1), thereby increasing the water pressure difference between the water collection well (1) and the recharge well (2); If the water level in the recharge well (2) reaches the maximum control water level, the intelligent control unit (51) receives the water level information from the recharge well water level sensor (521) and turns off the water pump (42); the water level difference between the water collection well (1) and the recharge well (2) becomes smaller, the flow rate of recharge to the surrounding soil layer decreases, and the water level in the recharge well (2) also drops. If the water level in the recharge well (2) reaches the minimum control water level, the intelligent control unit (51) receives the water level information from the recharge well water level sensor (521) and starts the water pump (42); the water level difference between the water collection well (1) and the recharge well (2) increases, the flow rate of the recharged soil layer increases, and the water level in the recharge well (2) also rises.

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