A foundation pit gravity recharge method and system based on pre-water level control

Abstract

The application discloses a foundation pit gravity recharge method and system based on pre-water level control. The method comprises the following steps: calculating the water inlet valve opening time and the recharge valve opening time according to the predicted water level value and the predicted time extracted from the water level prediction data; controlling the water inlet valve to open at the water inlet valve opening time, and when the river water level is greater than the water storage container water level, the river water is injected into the water storage container through the water diversion channel; closing the water inlet valve when the water storage container water level rises to the full water level; controlling the recharge valve to open at the recharge valve opening time, and when the river water level is less than the water storage container water level, the water in the water storage container is injected into the recharge well through the recharge pipeline; and closing the recharge valve when the water storage container water level drops to the low water level. The application can control the valve according to the predicted water level, which helps to reduce the problem of insufficient utilization of natural water level difference caused by the lag of real-time feedback control.

Description

Technical Field

[0001] This application relates to the fields of foundation pit engineering and groundwater resource management technology, specifically to a method and system for gravity recharge of foundation pits based on pre-positioned water level control. Background Technology

[0002] During the construction of foundation pits, dewatering is typically required to lower the groundwater level below the excavation surface and ensure dry working conditions. However, dewatering alters the surrounding groundwater seepage field, potentially causing environmental problems such as ground subsidence and tilting of nearby buildings. To mitigate the impact of dewatering on the surrounding environment, foundation pit recharge technology has emerged. This involves reinjecting extracted groundwater or treated surface water into the aquifers surrounding the foundation pit through recharge wells to maintain a stable groundwater level.

[0003] Existing foundation pit recharge technologies all revolve around the technical approach of pumping water and pressurizing it for recharge, using electrically driven pumps to pressurize treated water and inject it into the recharge well. In most of the existing solutions, recharge is entirely dependent on electric pumps.

[0004] In areas where water levels fluctuate periodically or predictably (such as coastal or tidal river sections), a natural head difference exists between the river level and the target water level for foundation pit recharge. This head difference has renewable driving potential, but it has not been utilized as a pre-emptive water level control method in the current field of foundation pit recharge. Even in existing solutions that respond to water level changes, the control logic remains at the real-time water level feedback level, meaning that valve action is only triggered after the water level reaches a threshold. There is no solution that provides pre-emptive timing control of the inlet and recharge valves based on predicted water level data.

[0005] The aforementioned problems mean that existing foundation pit recharge systems still have significant room for energy conservation and consumption reduction in areas with natural water level differences, and there is an urgent need for a foundation pit recharge scheme based on pre-judgment control of water level rather than real-time feedback control. Summary of the Invention

[0006] This application aims to propose a method and system for gravity recharge of foundation pits based on pre-controlled water level. By calculating and controlling the opening time of the inlet valve and recharge valve in advance based on the predicted water level data, the water head difference between the natural water level of the river and the water level of the storage container drives water storage and recharge. This solves the problem that existing foundation pit recharge systems rely on real-time water level feedback control, which leads to valve action lag and the inability to fully utilize the natural water level difference for gravity recharge.

[0007] In existing foundation pit recharge schemes, the control of inlet and recharge valves typically relies on real-time water level sensor feedback, meaning the valves are only triggered after the water level reaches a certain threshold. This real-time feedback control method has an inherent lag in scenarios where river water levels change rapidly. When water levels rise and fall rapidly, the valve opening time may be significantly later than the optimal water storage or recharge window, leading to insufficient water storage or recharge interruption. If advance water level forecast data can be incorporated into the valve control logic, triggering valve action before the forecast water level reaches the target threshold, the water storage and recharge process can be synchronized with water level changes, fully utilizing natural water level differences to drive recharge and reducing reliance on electric power.

[0008] To achieve the above objectives, this application provides a method for gravity recharge of foundation pits based on pre-controlled water level. By using predictable water level data as a pre-signal for valve control, the valve opening preparation is completed before the predicted water level reaches the target threshold, so that water storage and recharge are synchronized with water level changes.

[0009] This application discloses a gravity recharge method for foundation pits based on pre-positioned water level control. The method involves introducing river water from a river channel into a storage container via a diversion channel when the river level rises, and then introducing the river water from the storage container into a recharge well when the river level drops. The diversion channel is equipped with an inlet valve. The storage container has an inlet and an outlet at its center, with the outlet positioned lower than the inlet. The inlet is connected to the diversion channel, and the outlet is connected to the wellhead of the recharge well via a recharge pipeline equipped with a recharge valve. The method includes at least the following steps: initially, both the inlet valve and the recharge valve are closed; calculating the opening time of the inlet valve and the recharge valve based on the predicted water level value extracted from water level forecast data and the corresponding predicted time; controlling the inlet valve to open at the specified opening time; and when the river level is higher than the specified water level, the method continues until the water level drops. When the water level in the water container reaches a preset full level, river water is injected into the water storage container through the water diversion channel. When the water level in the water storage container rises to a preset full level, or when the water level in the water storage container stops rising but does not reach the preset full level, the inlet valve is controlled to close. The full level is higher than the inlet. The criterion for determining when the water level stops rising is that the absolute value of the maximum change in the water level of the water storage container is lower than a preset detection threshold within a preset time window. When the inlet valve is closed and the water level in the water storage container is higher than the wellhead of the reinjection well, the reinjection valve is controlled to open during the reinjection valve opening time, and the river water in the water storage container is injected into the reinjection well through the reinjection pipeline. When the water level in the water storage container drops to a preset low level, the reinjection valve is controlled to close. The low level is higher than the outlet and lower than the inlet.

[0010] Optionally, the calculation method for the opening time of the inlet valve is as follows: extract the first and second water level values ​​adjacent to the preset inlet valve opening water level from the water level forecast data. The inlet valve opening water level is greater than the inlet of the water storage container and less than the full water level, and the first water level value is less than the second water level value. The time node when the river water level rises to the inlet valve opening water level during the river water level rise process is calculated by the first interpolation method, which is the inlet valve opening time. The calculation method for the opening time of the recharge valve is as follows: extract the third and fourth water level values ​​adjacent to the preset recharge valve opening water level from the water level forecast data. The recharge valve opening water level is greater than the inlet valve opening water level and less than the full water level, and the third water level value is greater than the fourth water level value. The time node when the river water level falls to the recharge valve opening water level during the river water level fall process is calculated by the second interpolation method, which is the recharge valve opening time.

[0011] Optionally, an electric pump is installed in the reinjection pipeline; when the reinjection valve is in the open state, the method further includes controlling the electric pump according to the height difference between the water level in the water storage container and the wellhead of the reinjection well: when the height difference is greater than or equal to a first preset threshold, the electric pump does not start; when the height difference is less than the first preset threshold but greater than or equal to a second preset threshold, the electric pump operates at a first power; when the height difference is less than the second preset threshold, the electric pump operates at full power until the water level in the water storage container drops to the low water level and the reinjection valve is closed; wherein, the first preset threshold is greater than the second preset threshold, and the first power is less than the full power.

[0012] Optionally, the water storage container is equipped with a water level sensor for monitoring the water level of the water storage container; when the water level of the water storage container exceeds the preset upper limit of the safe water level, the inlet valve is forcibly closed; when the water level of the water storage container is lower than the preset lower limit of the safe water level, the recharge valve is forcibly closed; the upper limit of the safe water level is higher than the full water level, and the lower limit of the safe water level is lower than the low water level and higher than the outlet of the water storage container.

[0013] Optionally, the water storage container includes a first water storage container and a second water storage container, which alternately store and recharge water, with staggered storage and release phases, so that at least one of the water storage containers is in a rechargeable state at any given time; the end of the water diversion channel is divided into a first water diversion branch and a second water diversion branch; the first water diversion branch is connected to the inlet of the first water storage container, and a first water inlet valve is provided in the first water diversion branch; the second water diversion branch is connected to the inlet of the second water storage container, and a second water inlet valve is provided in the second water diversion branch; the front end of the recharge pipeline is divided into a first recharge branch and a second recharge branch; the first recharge branch is connected to the outlet of the first water storage container, and a first recharge valve is provided in the first recharge branch; the second recharge branch is connected to the outlet of the second water storage container, and a second recharge valve is provided in the second recharge branch.

[0014] This application also provides a gravity recharge system for foundation pits based on pre-positioned water level control, used to implement the method described above. The system includes a water diversion channel, a water storage container, a recharge pipeline, a recharge well, and a controller. The water storage container has an inlet and an outlet in its middle, with the outlet positioned lower than the inlet. The water diversion channel connects the river to the inlet of the water storage container, and an inlet valve is installed in the water diversion channel. The recharge pipeline connects the outlet of the water storage container to the wellhead of the recharge well, and a recharge valve is installed in the recharge pipeline. The controller is configured to calculate the opening time of the inlet valve and the opening time of the recharge valve based on the predicted water level value extracted from water level forecast data and the predicted time corresponding to the predicted water level value. The controller controls the inlet valve to open at the specified opening time. When the water level in the river is higher than the water level in the water storage container, river water is injected into the foundation pit through the water diversion channel. In the aforementioned water storage container; when the water level in the water storage container rises to a preset full level, or when the water level in the water storage container stops rising but does not rise to the preset full level, the inlet valve is controlled to close, and the position of the full level is higher than the position of the inlet; the determination criterion for the water level to stop rising is: within a preset time window, the absolute value of the maximum change in the water level of the water storage container is lower than a preset detection threshold; when the inlet valve is closed and the water level in the water storage container is higher than the wellhead of the reinjection well, the reinjection valve is controlled to open at the opening time of the reinjection valve, and when the water level in the river is lower than the water level in the water storage container, the river water in the water storage container is injected into the reinjection well through the reinjection pipeline; when the water level in the water storage container drops to a preset low level, the reinjection valve is controlled to close, and the position of the low level is higher than the position of the outlet and lower than the position of the inlet.

[0015] Optionally, the calculation method for the opening time of the inlet valve is as follows: extracting a first water level value and a second water level value adjacent to the preset inlet valve opening water level from the water level forecast data, wherein the inlet valve opening water level is greater than the inlet of the water storage container and less than the full water level, and the first water level value is less than the second water level value; calculating the time node when the river water level rises to the inlet valve opening water level during the river water level rise process using a first interpolation method, and using this as the opening time of the inlet valve; and the calculation method for the opening time of the recharge valve is as follows: extracting a third water level value and a fourth water level value adjacent to the preset recharge valve opening water level from the water level forecast data, wherein the recharge valve opening water level is greater than the inlet valve opening water level and less than the full water level, and the third water level value is greater than the fourth water level value; calculating the time node when the river water level falls to the recharge valve opening water level during the river water level fall process using a second interpolation method, and using this as the opening time of the recharge valve.

[0016] Optionally, an electric pump is installed in the reinjection pipeline, and the electric pump is connected to the controller. When the reinjection valve is open, the controller controls the electric pump according to the height difference between the water level in the storage container and the wellhead of the reinjection well: when the height difference is greater than or equal to a first preset threshold, the electric pump does not start; when the height difference is less than the first preset threshold and greater than or equal to a second preset threshold, the electric pump operates at a first power; when the height difference is less than the second preset threshold, the electric pump operates at full power; wherein, the first preset threshold is greater than the second preset threshold, and the first power is less than the full power.

[0017] Optionally, the water storage container is equipped with a water level sensor, and the controller monitors the water level of the water storage container through the water level sensor; when the water level of the water storage container exceeds the preset safe water level upper limit, the controller forcibly closes the water inlet valve; when the water level of the water storage container is lower than the preset safe water level lower limit, the controller forcibly closes the recharge valve; the safe water level upper limit is higher than the full water level, and the safe water level lower limit is lower than the low water level and higher than the water outlet position of the water storage container.

[0018] Optionally, the water storage container includes a first water storage container and a second water storage container, which alternately store and recharge water, with staggered storage and release phases, so that at least one of the water storage containers is in a rechargeable state at any given time; the end of the water diversion channel is divided into a first water diversion branch and a second water diversion branch; the first water diversion branch is connected to the inlet of the first water storage container, and a first water inlet valve is provided in the first water diversion branch; the second water diversion branch is connected to the inlet of the second water storage container, and a second water inlet valve is provided in the second water diversion branch; the front end of the recharge pipeline is divided into a first recharge branch and a second recharge branch; the first recharge branch is connected to the outlet of the first water storage container, and a first recharge valve is provided in the first recharge branch; the second recharge branch is connected to the outlet of the second water storage container, and a second recharge valve is provided in the second recharge branch.

[0019] This application provides a method and system for gravity recharge of foundation pits based on pre-positioned water level control. By calculating the opening time of the inlet valve and the recharge valve according to the predicted water level data, the inlet valve and the recharge valve are prepared to open before the predicted water level reaches the target value. When a head difference is formed between the river water level and the water level of the storage container, the system drives water storage or recharge. This changes the control logic of the recharge system from real-time feedback to pre-positioned prediction, reducing the problem of insufficient utilization of the water level difference caused by valve lag. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 A schematic diagram of one embodiment of the system provided in this application; Figure 2 A flowchart illustrating the method provided in the embodiments of this application; Figure 3 A schematic diagram of another embodiment of the system provided in this application.

[0022] Key reference numerals: 1. Water diversion channel; 11. Inlet valve; 12. First water diversion branch; 13. Second water diversion branch; 14. First inlet valve; 15. Second inlet valve; 2. Water storage container; 21. Inlet; 22. Outlet; 23. First water storage container; 24. Second water storage container; 3. Recharge pipeline; 31. Recharge valve; 32. First recharge branch; 33. Second recharge branch; 34. First recharge valve; 35. Second recharge valve; 36. First electric pump; 37. Second electric pump; 4. Recharge well; 5. Controller; 6. River channel; 7. Sedimentation tank; 71. Valve; 8. Coarse filter layer; 9. Electric pump; H1. Full water level; H2. Low water level; H3. Upper limit of safe water level; H4. Lower limit of safe water level. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings. The described embodiments should not be regarded as limitations on this application. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0024] Unless otherwise defined, all technical and scientific terms used in the embodiments of this application have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in the embodiments of this application is for the purpose of describing the embodiments of this application only and is not intended to limit this application.

[0025] like Figure 1 As shown, this application provides a gravity recharge system for foundation pits based on pre-positioned water level control (hereinafter referred to as the "system"), such as... Figure 2 As shown, this application also provides a gravity recharge method for foundation pits based on pre-controlled water level (hereinafter referred to as the "method"). The method and system are used to introduce river water from the river channel into a storage container via an irrigation canal when the river water level rises, and then introduce the river water from the storage container into a recharge well when the river water level drops. The method and system pre-control the opening time of the inlet valve and the recharge valve based on predicted water level data. When a head difference is formed between the river water level and the water level in the storage container, this head difference is used to drive water storage and recharge. This aims to transform the control logic of the recharge system from real-time feedback to pre-prediction, thereby fully utilizing the natural water level difference to drive recharge and reducing power consumption.

[0026] The system includes a water diversion channel 1, a water storage container 2, a reinjection pipeline 3, a reinjection well 4, and a controller 5. The water storage container 2 has an inlet 21 and an outlet 22 in its middle, with the outlet 22 positioned lower than the inlet 21. The water diversion channel 1 connects the river channel 6 to the inlet 21 of the water storage container 2, and an inlet valve 11 is installed in the water diversion channel 1. The reinjection pipeline 3 connects the outlet 22 of the water storage container 2 to the wellhead of the reinjection well 4, and a reinjection valve 31 is installed in the reinjection pipeline 3.

[0027] The method is implemented through the aforementioned system. The method includes at least an initial stage and a control stage. In the initial stage, both the inlet valve 11 and the recharge valve 31 are initially closed, ensuring the system is in a controllable static state before startup and preventing water loss or uncontrolled recharge due to unexpected opening of the inlet valve 11 and recharge valve 31. The controller 5 is configured to implement the control stage, which further includes a water storage sub-stage and a recharge sub-stage, and is completed through the following steps.

[0028] Step S1: Calculate the opening time of the inlet valve and the recharge valve. The opening times of the inlet valve and the recharge valve are calculated based on the predicted water level value extracted from the water level forecast data and the corresponding predicted time. In this application, the water level forecast data refers to data predicting the river water level change over time based on hydrological patterns (including astronomical tidal patterns), and includes at least the predicted water level value and the corresponding predicted time. Water level changes in natural water bodies (especially tidal rivers) are highly predictable, and their rise and fall times can be known in advance. By using the water level forecast data to determine the opening time of the inlet valve 11 and the recharge valve 31 in advance, feedforward control based on the water level forecast data is achieved instead of control based on the real-time water level. This avoids the opening actions of the inlet valve 11 and the recharge valve 31 lagging behind water level changes, thereby affecting the efficiency of water storage and recharge.

[0029] Step S2: Enter the water storage sub-stage. The inlet valve 11 is opened according to the specified opening time. During the rise of the river water level, when the water level of the river 6 is higher than the water level of the storage container 2, the head difference between the water levels of the river 6 and the storage container 2 is used to allow the river water to flow into the storage container 2 through the diversion channel 1 under gravity, converting the potential energy of the water level difference into the potential energy of the river water in the storage container 2 and storing it.

[0030] Step S3: End the water storage sub-stage. When the water level in the water storage container 2 rises to the preset full water level H1, or when the water level in the water storage container 2 stops rising but does not reach the preset full water level H1, the inlet valve 11 is closed. The full water level H1 is the preset water level at which the water storage container 2 stops receiving water, and the position of the full water level H1 is higher than the position of the outlet 22. Under the condition that the river water in the river channel 6 can rise to the point that the water level in the water storage container 2 reaches the full water level H1, as the water level in the river channel 6 continues to rise, the water level in the water storage container 2 rises accordingly. When the water level in the water storage container 2 reaches the full water level H1, the inlet valve 11 is closed, ending the water storage sub-stage and entering the recharge sub-stage, ensuring that the water level in the water storage container 2 is sufficient to achieve subsequent recharge and avoiding excessive water intake that could lead to overflow or structural overload. When the water level in river 6 cannot rise to the full level H1 required to fill water storage container 2, the water level in water storage container 2 will stop rising when the water level in river 6 begins to drop. If the inlet valve 11 is still open at this time, water storage container 2 cannot continue to fill and cannot enter the recharge sub-stage (the recharge sub-stage can only be entered when the inlet valve 11 is closed). Therefore, when the water level in water storage container 2 stops rising but does not reach the preset full level H1, the inlet valve 11 needs to be closed to end the water storage sub-stage and enter the recharge sub-stage. The criterion for determining when the water level stops rising is: within a preset time window, the maximum change in the water level of water storage container 2 is lower than a preset detection threshold. When the maximum change in the water level in water storage container 2 is lower than the detection threshold, it indicates that the water level in water storage container 2 has stabilized. Whether the water level in river 6 continues to rise or the water level in river 6 can no longer rise and has begun to drop, the inlet valve 11 can be closed. When the water level in the water storage container 2 rises to the preset full water level H1, or when the water level in the water storage container 2 stops rising but does not rise to the preset full water level H1, the water inlet valve 11 is controlled to close, ensuring that the system can transition from the water storage sub-stage to the recharge sub-stage under all water level conditions.

[0031] Step S4: Entering the reinjection sub-stage. When the inlet valve 11 is closed and the water level in the storage container 2 is higher than the wellhead of the reinjection well 4, the reinjection valve 31 is opened at the specified opening time. When the inlet valve 11 is closed, it indicates that the water storage sub-stage has ended. Then, during the water level drop in the river channel 6, when the water level in the storage container 2 is higher than the wellhead of the reinjection well 4, the head difference between the water level in the storage container 2 and the wellhead of the reinjection well 4 can be used to inject the river water in the storage container 2 into the reinjection well 4 through the reinjection pipeline 3, entering the reinjection state. This utilizes the potential energy of the river water stored in the storage container 2 to inject the river water from the storage container 2 into the reinjection well 4 and then reinject it into the formation, thus achieving reinjection.

[0032] Step S5: End the recharge sub-stage. When the water level in the storage container 2 drops to the preset low water level H2, the amount of river water available for recharge is limited, so the recharge valve 31 is closed. The low water level H2 is higher than the outlet 22 to ensure a water seal in the recharge pipeline 3, preventing air from entering and interrupting the recharge process. It also ensures that a certain amount of water is always maintained at the bottom of the storage container 2 to prevent bottom sediment from being carried into the recharge pipeline 3. When the water level in the storage container 2 drops to the low water level H2, the amount of river water available for recharge is limited, so the recharge valve 31 is closed. Simultaneously, the low water level H2 must be lower than the inlet 21 so that the inlet 21 remains above the water surface during the recharge process, facilitating smooth water intake during the next storage sub-stage.

[0033] This application starts from the initial state where both the inlet valve 11 and the recharge valve 31 are closed. During the high tide phase, the inlet valve 11 is opened according to the calculated opening time to enter the water storage sub-stage. The inlet valve 11 is closed to end the water storage sub-stage when the water level in the water storage container 2 rises to the full water level H1 or stops rising. During the low tide phase, the recharge valve 31 is opened according to the calculated opening time to enter the recharge sub-stage. The recharge valve 31 is closed to end the recharge sub-stage when the water level in the water storage container 2 drops to the preset low water level H2, returning to the initial state where both the inlet valve 11 and the recharge valve 31 are closed. This application executes sequentially according to this time sequence, forming a complete water storage and recharge cycle within a water level rise and fall cycle. This water storage and recharge cycle repeats itself with the rise and fall of the water level, repeating in each water level cycle, synchronizing the system's water storage and recharge with the natural rhythm of water level rise and fall. Feedforward control is achieved using water level forecast data and through the inlet valve 11 and the recharge valve 31.

[0034] In one feasible implementation, the calculation method for the opening time of the inlet valve is as follows: First and second water level values ​​adjacent to the preset inlet valve opening water level (not shown in the figure) are extracted from the water level forecast data. The inlet valve opening water level is greater than the inlet 21 of the water storage container 2 and less than the full water level H1. The first water level value is less than the second water level value. The time point at which the water level of the river 6 rises to the inlet valve opening water level during the river water level rise process is calculated using a first interpolation method, which is the opening time of the inlet valve. The calculation method for the opening time of the recharge valve is as follows: Third and fourth water level values ​​adjacent to the preset recharge valve opening water level (not shown in the figure) are extracted from the water level forecast data. The recharge valve opening water level is greater than the inlet valve opening water level and less than the full water level H1. The third water level value is greater than the fourth water level value. The time point at which the river water level falls to the recharge valve opening water level during the river water level fall process is calculated using a second interpolation method, which is the opening time of the recharge valve.

[0035] In this application, the water level at which the inlet valve opens refers to the threshold water level in river channel 6 that triggers the opening of inlet valve 11. Similarly, the water level at which the recharge valve opens refers to the threshold water level in river channel 6 that triggers the opening of recharge valve 31. Water level forecast data is typically hourly discrete data (one water level value per hour), but in actual engineering applications, the opening times of inlet valve 11 and recharge valve 31 need to be accurate to the minute. By using interpolation methods to refine the hourly discrete data of the water level forecast into minute-level time nodes, the opening time of the inlet valve is essentially matched with the time it takes for the water level in river channel 6 to reach the inlet valve opening level, and the opening time of the recharge valve is essentially matched with the time it takes for the water level in river channel 6 to reach the recharge valve opening level, thereby reducing the time deviation caused by the hourly discrete data.

[0036] The first interpolation method is one of linear interpolation, cubic spline interpolation, Hermite interpolation, or trigonometric interpolation; the second interpolation method is one of linear interpolation, cubic spline interpolation, Hermite interpolation, or trigonometric interpolation. The first and second interpolation methods can be the same or different. Optionally, both the first and second interpolation methods may use Hermite interpolation, as it balances the matching degree with water level physical characteristics, mathematical accuracy, and engineering practicality.

[0037] In one specific embodiment, the water storage container 2 is equipped with a water level sensor for monitoring the water level of the water storage container 2. During the water storage sub-stage, when the water level of the water storage container 2 exceeds the preset safe water level upper limit H3, the inlet valve 11 is forcibly closed. The safe water level upper limit H3 is higher than the full water level H1. When the water level of the water storage container 2 exceeds the full water level H1 and continues to rise to the safe water level upper limit H3 due to water level prediction deviation, inlet valve response delay, etc., a signal to forcibly close the inlet valve 11 is triggered, directly closing the inlet valve 11 to prevent overflow. During the recharge sub-stage, when the water level of the water storage container 2 is lower than the preset safe water level lower limit H4, the recharge valve 31 is forcibly closed. The safe water level lower limit H4 is lower than the low water level H2 and higher than the outlet of the water storage container 2. When the water level in the water storage container 2 drops to the lower limit of the safe water level H4 due to reasons such as excessively fast recharge rate or water level prediction deviation, a signal is triggered to force the recharge valve 31 to close directly, preventing air from entering the recharge pipeline 3 or the electric pump 9 from running dry (when the electric pump 9 is installed in the recharge pipeline 3).

[0038] During the reinjection process, when the height difference between the water level in the storage container 2 and the wellhead of the reinjection well is small, the reinjection flow rate will decrease accordingly. For example, as time progresses during the reinjection process, the water level in the storage container 2 will gradually decrease, and the height difference between the water level in the storage container 2 and the wellhead of the reinjection well 4 will decrease at any time; or, when entering the reinjection sub-stage, the water level in the storage container 2 has not reached the full water level H1, and the height difference between the water level in the storage container 2 and the wellhead of the reinjection well 4 is already small. In an optional embodiment, an electric pump 9 is installed in the reinjection pipeline 3. When the reinjection valve 31 is open, i.e., when the system is in the reinjection sub-stage, the method further includes controlling the electric pump 9 based on the height difference between the water level in the water storage container 2 and the wellhead of the reinjection well 4: when the height difference is greater than or equal to a first preset threshold, the river water in the water storage container 2 can enter the reinjection well 4 under gravity and reach the designed reinjection volume, without the need for electric pump assistance, the electric pump does not start, and there is zero energy consumption in this stage; when the height difference is less than the first preset threshold but greater than or equal to a second preset threshold, the river water in the water storage container 2 cannot reach the designed reinjection volume under gravity alone, but... The gap is small, requiring only a low-power booster pump to achieve the designed reinjection volume. The pump 9 operates at its first power, resulting in low energy consumption during this stage. When the height difference is less than the second preset threshold, the river water in the storage container 2 cannot be injected into the reinjection well 4 by gravity alone. The pump 9 must operate at full power to maintain reinjection. In this case, the actual reinjection volume in the storage container 2 is allowed to be lower than the designed reinjection volume until the water level in the storage container 2 drops to the low water level H2, at which point the reinjection valve 31 is closed. The first preset threshold is greater than the second preset threshold, and the first power is less than the full power. Throughout the entire reinjection sub-stage, full power operation is not required, thus reducing power consumption while ensuring continuous reinjection.

[0039] Optionally, the first preset threshold The critical height difference used to determine whether the actual recharge volume in gravity storage container 2 alone can meet the design recharge volume is calculated as follows: ,in, For the total head loss of the pipeline, The minimum effective head is obtained by inverse calculation using Thiem's ​​formula. The calculation formula is as follows: ,in To design the reinjection volume, To affect the radius, The radius of the recharge well. The aquifer permeability coefficient is... This refers to the aquifer thickness. The methods used to obtain the above parameters are standard techniques in the field of foundation pit dewatering and recharge engineering: design recharge volume. The radius of influence is determined by the design requirements for dewatering of the foundation pit. The permeability coefficient is estimated using empirical formulas based on the permeability coefficient and aquifer thickness, or by using observations from on-site pumping tests. Aquifer thickness obtained through on-site pumping or injection tests. The head loss of the pipeline is obtained through geological exploration drilling. It can be calculated using the Darcy-Weisbach formula, or by referring to the hydraulic calculation tables in the "Water Supply and Drainage Design Manual," obtaining the head loss per unit length, multiplying it by the pipeline length, and then adding local losses from pipe fittings. Alternatively, it can be estimated in the preliminary design stage as 30% to 50% of the water level difference (the height difference between the highest and lowest water levels within a water level fluctuation cycle). The above calculation methods and engineering estimation methods are conventional techniques used by those skilled in the art in the design of foundation pit recharge projects. When implementing the technical solution of this application, those skilled in the art can use the above methods to determine the minimum effective head and the total head loss of the pipeline according to specific engineering conditions. The specific calculation process will not be elaborated in this specification.

[0040] Optionally, the second preset threshold The formula used to define the critical point between the electric pump 9 operating at its first power and operating at full power is as follows: , For the total head loss of the pipeline, This is the minimum effective head required for the electric pump to operate at full power. When the height difference between the water level in storage container 2 and the wellhead of reinjection well 4 is equal to... At that time, the effective head provided by gravity alone is exactly equal to When electric pump 9 is running at full power, and The sum of these amounts is just enough to meet the design reinjection volume. At this point... The value is less than the first preset threshold in the calculation. This is because the electric pump 9 at full power provides additional driving force. In engineering practice, the second preset threshold can be determined by referring to the pump characteristic curve, based on the head-flow characteristic curve of the selected electric pump 9 at full power operation, combined with the pipeline resistance characteristics. The second preset threshold can also be determined through actual measurement during the system commissioning phase, based on the power characteristics of the electric pump 9, the hydraulic characteristics of the pipeline, and the design reinjection volume requirements. When the actual reinjection volume decreases below the design reinjection volume as the water level in the water storage container 2 drops, the height difference corresponding to the lowest effective reinjection volume that the electric pump 9 can maintain at full power is set as the engineering setting value of the second preset threshold.

[0041] In actual engineering practice, the first and second preset thresholds obtained above are used as initial design parameters. During the system commissioning phase, they are verified and fine-tuned based on the measured reinjection flow rate to ensure that the graded control of electric pump 9 matches the designed reinjection volume.

[0042] If the duration of the water level drop phase in a single water level fluctuation cycle is long, the duration of continuous recharge after a single water storage container 2 is filled is insufficient to cover the entire rechargeable water level window. To achieve continuous recharge within a single water level fluctuation cycle, such as... Figure 3 As shown, in one embodiment of this application, the water storage container 2 includes a first water storage container 23 and a second water storage container 24. The first water storage container 23 and the second water storage container 24 alternately store and refill water, with staggered storage and release phases, so that at any given time, at least one of the water storage containers is in a refillable state, such that when the first water storage container 23 stores water, the second water storage container 24 refills water, and when the first water storage container 23 refills water, the second water storage container 24 stores water. The end of the water diversion channel 1 is divided into a first water diversion branch 12 and a second water diversion branch 13. The first water diversion branch 12 is connected to the inlet of the first water storage container 23, and the... A first inlet valve 14 is installed in the first water intake branch 12; the second water intake branch 13 is connected to the inlet of the second water storage container 24, and a second inlet valve 15 is installed in the second water intake branch 13; the front end of the reinjection pipeline 3 is divided into a first reinjection branch 32 and a second reinjection branch 33; the first reinjection branch 32 is connected to the outlet of the first water storage container 23, and a first reinjection valve 34 is installed in the first reinjection branch 32; the second reinjection branch 33 is connected to the outlet of the second water storage container 24, and a second reinjection valve 35 is installed in the second reinjection branch 33. Furthermore, a first electric pump 36 can be installed in the first reinjection branch 32, and a second electric pump 37 can be installed in the second reinjection branch 33.

[0043] The technical solution of this application will be further described below with reference to specific embodiments.

[0044] Example 1: This example is applied to a deep foundation pit project in a coastal city. The foundation pit is approximately 12m deep, surrounded by marine sand layers with permeability coefficients that meet the system's applicability requirements. The designed recharge volume is determined based on the foundation pit's dewatering needs and groundwater level maintenance requirements. The site is adjacent to a tidal river channel with a significant daily water level difference, providing conditions for utilizing this difference for pre-emptive water level control. An existing flood control dike top exists within the site, serving as a natural support platform for the water storage container 2.

[0045] The water storage container 2, constructed of lightweight steel, is installed atop the flood control dike. An inlet valve is installed on the riverbank. A water diversion channel is laid from the inlet valve to the water storage container 2. Typically, water level sensors are installed on the riverbank to monitor the river level. In this embodiment, a water level sensor is also installed on the side wall of the water storage container 2 to monitor its water level. Figure 1As shown, a sedimentation tank 7 and a coarse filter layer 8 are also installed on the reinjection pipeline 3 to filter the river water. If there is no need to filter the river water, the sedimentation tank 7 and the coarse filter layer 8 can be omitted. A valve 71 is installed on the connecting pipeline between the sedimentation tank 7 and the reinjection pipeline 3. A small-power electric pump 9 is installed at the end of the reinjection pipeline 3, and its power is much lower than that of a conventional full-pressure reinjection system.

[0046] Configure controller 5 (PLC), connect to local water level forecast data, and set preset control thresholds such as the upper limit of safe water level H3 (e.g., full water level H1 + 0.2m), full water level H1 (e.g., 90% of the effective height of water storage container 2), inlet 21 (e.g., 40% of the effective height of water storage container 2), low water level H2 (e.g., 15% of the effective height of water storage container 2), lower limit of safe water level H4 (e.g., low water level H2 - 0.1m), and outlet 22 (e.g., 8% or 10% of the effective height of water storage container 2). The upper limit of safe water level H3 means that when the water level of water storage container 2 exceeds the full water level H1 by a certain margin, the inlet valve 11 will be forcibly closed. The lower limit of safe water level H4 means that when the water level of water storage container 2 is lower than the low water level H2 by a certain margin, the recharge valve 31 will be forcibly closed.

[0047] During operation, the PLC calculates the opening times of the inlet valve and the recharge valve based on water level forecast data. During the rising water level phase (e.g., during high tide), the PLC controls the inlet valve 11 to open at the designated opening time. The water level in the river 6 can then rise to the preset inlet valve opening level, allowing the inlet valve 11 to open and the river water to flow into the storage container 2 under gravity. The inlet valve 11 closes when the water level in the storage container 2 reaches the full level H1. During the falling water level phase (e.g., during low tide), the water level in the river 6 drops. If the water level in the storage container 2 is higher than the wellhead of the recharge well 4, the recharge valve 31 opens, allowing the river water in the storage container 2 to flow into the recharge well 4 through the recharge pipeline 3 under gravity. The recharge valve 31 closes when the water level in the storage container 2 drops to the low level H2. When the water level in the water storage container 2 exceeds the full water level H1 by a certain margin and reaches the preset safe water level upper limit H3, the water level sensor in the water storage container 2 triggers the forced closure of the inlet valve 11; when the water level in the water storage container 2 is lower than the low water level H2 by a certain margin and reaches the preset safe water level lower limit H4, the water level sensor in the water storage container 2 triggers the forced closure of the recharge valve 31.

[0048] Test results show that, under suitable conditions where the daily water level difference meets the applicable requirements, gravity flow reinjection accounts for a large proportion of the reinjection cycle. Pump 9 only operates at 60% of its full power (this is a preset value, i.e., the first power) when the water level in the storage container 2 drops to a certain position, and only operates at full power when the water level in the storage container 2 continues to drop to a lower position. The operating time of pump 9 is significantly reduced compared to conventional full-pressure reinjection systems.

[0049] Example 2: This example is applied to a large-scale foundation pit project. The pit is adjacent to a drinking water source recharge area, and the recharge water quality requirements are relatively strict. The pit is approximately 15m deep, and the stratum is a layer of fine silt with a medium to low permeability. The designed recharge volume is large, the daily water level difference at the site is approximately 2.8m, and the site conditions allow for the installation of a dual-pool system. This example focuses on verifying the applicability of enhanced water treatment configuration and the timing matching of alternating dual-pool systems.

[0050] like Figure 2 As shown, this embodiment includes a first water storage container 23 and a second water storage container 24. The effective volume of each container meets the water storage requirement for a single operation. The two containers operate alternately: the first water storage container 23 stores water as the river level rises and releases water as the river level falls; the second water storage container 24 stores water during the next rise in river level and releases water during the next fall in river level. The PLC controls the first inlet valve 14, the second inlet valve 15, the first recharge valve 34, and the second recharge valve 35, respectively, to stagger the storage and release phases of the first and second water storage containers 23 and 24, ensuring that at least one container is in a releaseable state at any given time, thus achieving continuous recharge.

[0051] In addition to a sedimentation tank (not shown in the figure) and a coarse filter layer (not shown in the figure) in the first reinjection branch 32 and the second reinjection branch 33 of the second water storage container 24, which are connected to the first water storage container 23, an electrically powered self-cleaning filter (not shown in the figure) is also installed. The concentration of suspended solids in the effluent meets the water quality requirements for reinjection in the drinking water source replenishment area. Because of the addition of the electrically powered self-cleaning filter, the power of the first electric pump 36 and the second electric pump 37 needs to be increased accordingly.

[0052] In this embodiment, the first water storage container 23 and the second water storage container 24 are alternately configured, effectively alleviating the problem that a single water storage container cannot meet the continuous reinjection requirements during the water storage phase. Furthermore, it significantly improves reinjection under gravity, and the operating time of the first electric pump 36 and the second electric pump 37 is further reduced compared to configuring a single water storage container. The water quality effluent from the electric self-cleaning filter meets the reinjection requirements of sensitive aquifers.

[0053] Example 3: The project site in this example is a foundation pit in a coastal industrial zone. The daily water level difference is larger during periods of high water level difference and relatively smaller during periods of low water level difference. The formation permeability coefficient meets the system's applicability requirements. See [link / reference] Figure 1The system is configured with a single water storage container 2, and a sedimentation tank and coarse filter layer are installed in the reinjection pipeline 3. A low-power electric pump is also installed in the reinjection pipeline 3. The PLC reads the water level forecast data. During the rise of the river water level, the highest water level of the river 6 is insufficient to allow the water level of the water storage container 2 to reach the full water level H1. Therefore, during the water storage sub-stage, the river water in the river 6 is normally introduced into the water storage container 2 through the water diversion channel 1, and the reinjection is completed by the electric pump 9 during the reinjection sub-stage. The actual reinjection volume is lower than the designed reinjection volume.

[0054] During the test, the system’s average daily reinjection volume reached about 60% of the designed reinjection volume. The electric pump 9 continued to run during the reinjection sub-stage. Even so, because the electric pump 9 first ran at the first power (preset to 50% of the full power) and then at full power, the equivalent full power running time of the electric pump 9 was still significantly lower than that of the existing conventional scheme.

[0055] In the above three embodiments, the effective volume of the water storage container, the setting ratio of full water level and low water level, and the difference in the first power of the electric pump are adaptive adjustments made according to different engineering conditions (recharge volume, water level difference, formation permeability coefficient, site space). All of these are parameters that can be freely adjusted within the scope of protection of this application and do not change the core inventive concept of this application.

[0056] Based on the above technical solution, this application provides a method and system for gravity recharge of foundation pits based on pre-positioned water level control, which achieves the following in the field of foundation pit recharge: 1. This application calculates the opening time of the inlet valve and the recharge valve based on water level forecast data. During the rise of the river water level, the head difference between the river water level and the water level in the storage container is used to introduce river water into the storage container for storage. During the rise of the river water level, the head difference between the water level in the storage container and the recharge well opening is used to drive the recharge water through the recharge pipeline into the recharge well. Compared with the gravity recharge scheme that relies on electric water pumps for water replenishment in the prior art, this application converts most of the energy source from electricity to the natural potential energy of the water level difference, thereby reducing the power consumption of the recharge system. 2. This application calculates the opening time of the inlet valve and the recharge valve based on water level forecast data, so that the inlet valve opens before the forecast water level reaches the preset inlet valve opening level and the recharge valve opens before the forecast water level reaches the preset recharge valve opening level, rather than responding only after the water level is reached; compared with the existing control schemes that rely on real-time response from sensors, the control logic of this application is predictive, which can avoid valve action lag caused by differences in water level change rate and improve the timing matching degree between water storage and recharge and water level changes; 3. This application uses a water level sensor to forcibly close the inlet valve when the water level in the storage container exceeds the upper limit of the safe water level and to forcibly close the recharge valve when the water level in the storage container is lower than the lower limit of the safe water level. It intervenes in case of forecast deviation or abnormal operating conditions to prevent the water storage container from overflowing or the recharge pipeline from running dry. 4. This application controls the electric pump in stages according to the height difference between the water level in the storage container and the wellhead of the reinjection well. When the head difference is sufficient, the reinjection is driven by gravity flow, and when the head difference is insufficient, the pump is boosted with low power. This significantly reduces the running time of the electric pump compared to conventional full-pressure reinjection systems. 5. This application sets up two water storage containers to alternately store and recharge water, so that at least one water storage container is in a rechargeable state at any time, eliminating the period when a single water storage container cannot be recharged during water storage, and realizing the timing matching of intermittent water storage and continuous recharge.

[0057] The above descriptions are merely embodiments of this application. Commonly known technical solutions or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solution of this application. These modifications and improvements should also be considered within the scope of protection of this application, and will not affect the effectiveness of the application or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A method for gravity recharge of foundation pits based on pre-positioned water level control, characterized in that, The method is used to divert river water from a river channel into a storage container via an irrigation canal when the river level rises, and then divert the water from the storage container into a recharge well when the river level drops. The irrigation canal is equipped with an inlet valve. The storage container has an inlet and an outlet in its middle section, with the outlet positioned lower than the inlet. The inlet is connected to the irrigation canal, and the outlet is connected to the recharge well opening via a recharge pipeline equipped with a recharge valve. The method includes at least the following: Initially, both the inlet valve and the recharge valve are in the closed state; The opening times of the inlet valve and the recharge valve are calculated based on the predicted water level values ​​extracted from the self-water level forecast data and the predicted times corresponding to the predicted water level values. The water inlet valve is opened at the specified opening time. When the water level in the river is higher than the water level in the water storage container, the river water is injected into the water storage container through the water diversion channel. When the water level in the water storage container rises to a preset full level, or when the water level in the water storage container stops rising but does not rise to the preset full level, the water inlet valve is controlled to close, and the position of the full level is higher than the position of the water inlet; the determination criterion for the water level to stop rising is: within a preset time window, the absolute value of the maximum change in the water level of the water storage container is lower than a preset detection threshold. When the inlet valve is closed and the water level in the storage container is higher than the wellhead of the recharge well, the recharge valve is opened at the opening time of the recharge valve, and the river water in the storage container is injected into the recharge well through the recharge pipeline. When the water level in the water storage container drops to a preset low water level, the recharge valve is controlled to close. The low water level is higher than the outlet and lower than the inlet.

2. The method according to claim 1, characterized in that, The calculation method for the inlet valve opening time is as follows: Extract the first and second water level values ​​adjacent to the preset inlet valve opening water level from the water level forecast data. The inlet valve opening water level is greater than the inlet of the storage container but less than the full water level, and the first water level value is less than the second water level value. The time point at which the river water level rises to the inlet valve opening water level during the river water level rise process is calculated using a first interpolation method is the inlet valve opening time. The calculation method for the recharge valve opening time is as follows: extract the third and fourth water level values ​​adjacent to the preset recharge valve opening water level from the water level forecast data. The recharge valve opening water level is greater than the inlet valve opening water level and less than the full water level, and the third water level value is greater than the fourth water level value. The time node when the river water level falls to the recharge valve opening water level during the river water level drop is calculated by the second interpolation method, which is the recharge valve opening time.

3. The method according to claim 1, characterized in that, An electric pump is installed in the reinjection pipeline; when the reinjection valve is in the open state, the method further includes controlling the electric pump according to the height difference between the water level in the water storage container and the wellhead of the reinjection well: When the height difference is greater than or equal to a first preset threshold, the electric pump will not start; When the height difference is less than a first preset threshold and greater than or equal to a second preset threshold, the electric pump operates at a first power. When the height difference is less than the second preset threshold, the electric pump runs at full power until the water level in the water storage container drops to the low water level and then the recharge valve is closed. Wherein, the first preset threshold is greater than the second preset threshold, and the first power is less than the full power.

4. The method according to claim 1, characterized in that, The water storage container is equipped with a water level sensor for monitoring the water level in the water storage container; when the water level in the water storage container exceeds the preset upper limit of the safe water level, the inlet valve is forcibly closed; when the water level in the water storage container is lower than the preset lower limit of the safe water level, the recharge valve is forcibly closed; the upper limit of the safe water level is higher than the full water level, and the lower limit of the safe water level is lower than the low water level and higher than the outlet of the water storage container.

5. The method according to any one of claims 1 to 4, characterized in that, The water storage container includes a first water storage container and a second water storage container. The first water storage container and the second water storage container alternately store water and refill water, with the storage and release phases staggered, so that at any given time, at least one of the water storage containers is in a refillable state. The end of the water diversion channel is divided into a first water diversion branch and a second water diversion branch; the first water diversion branch is connected to the inlet of the first water storage container, and a first water inlet valve is provided in the first water diversion branch; the second water diversion branch is connected to the inlet of the second water storage container, and a second water inlet valve is provided in the second water diversion branch. The front end of the reinjection pipeline is divided into a first reinjection branch and a second reinjection branch; the first reinjection branch is connected to the outlet of the first water storage container, and a first reinjection valve is installed in the first reinjection branch; the second reinjection branch is connected to the outlet of the second water storage container, and a second reinjection valve is installed in the second reinjection branch.

6. A gravity recharge system for foundation pits based on pre-positioned water level control, characterized in that, For implementing the method as described in any one of claims 1 to 5, the system includes a water diversion channel, a water storage container, a reinjection pipeline, a reinjection well, and a controller; the water storage container has an inlet and an outlet in its middle, the outlet being positioned lower than the inlet; the water diversion channel connects a river to the inlet of the water storage container, and an inlet valve is provided in the water diversion channel; the reinjection pipeline connects the outlet of the water storage container to the wellhead of the reinjection well, and a reinjection valve is provided in the reinjection pipeline; The controller is configured to calculate the opening time of the inlet valve and the opening time of the recharge valve based on the predicted water level value extracted from the water level forecast data and the predicted time corresponding to the predicted water level value; control the inlet valve to open at the specified opening time, so that when the water level in the river is higher than the water level in the storage container, river water is injected into the storage container through the diversion channel; control the inlet valve to close when the water level in the storage container rises to a preset full level, or when the water level in the storage container stops rising but has not risen to the preset full level; the full level is higher than the position of the inlet; the water level stops rising when the water level stops rising. The criteria for stopping the rise are as follows: within a preset time window, the absolute value of the maximum change in water level in the storage container is lower than a preset detection threshold; when the inlet valve is closed and the water level in the storage container is higher than the wellhead of the recharge well, the recharge valve is opened at the opening time of the recharge valve, and when the water level in the river is lower than the water level in the storage container, the river water in the storage container is injected into the recharge well through the recharge pipeline; when the water level in the storage container drops to a preset low water level, the recharge valve is closed, and the low water level is higher than the outlet and lower than the inlet.

7. The system according to claim 6, characterized in that, The calculation method for the inlet valve opening time is as follows: Extract a first water level value and a second water level value adjacent to the preset inlet valve opening water level from the water level forecast data. The inlet valve opening water level is greater than the inlet of the water storage container but less than the full water level, and the first water level value is less than the second water level value. Calculate the time point at which the river water level rises to the inlet valve opening water level during the river water level rise process using a first interpolation method, and use this as the inlet valve opening time. The calculation method for the recharge valve opening time is as follows: extract the third and fourth water level values ​​adjacent to the preset recharge valve opening water level from the water level forecast data. The recharge valve opening water level is greater than the inlet valve opening water level and less than the full water level. The third water level value is greater than the fourth water level value. The time node when the river water level falls to the recharge valve opening water level during the river water level drop is calculated by the second interpolation method and used as the recharge valve opening time.

8. The system according to claim 6, characterized in that, An electric pump is installed in the reinjection pipeline and is connected to the controller. When the reinjection valve is open, the controller controls the electric pump based on the height difference between the water level in the storage container and the wellhead of the reinjection well. When the height difference is greater than or equal to a first preset threshold, the electric pump will not start; When the height difference is less than the first preset threshold and greater than or equal to the second preset threshold, the electric pump operates at the first power. When the height difference is less than the second preset threshold, the electric pump operates at full power; Wherein, the first preset threshold is greater than the second preset threshold, and the first power is less than the full power.

9. The system according to claim 6, characterized in that, The water storage container is equipped with a water level sensor, and the controller monitors the water level of the water storage container through the water level sensor; when the water level of the water storage container exceeds the preset safe water level upper limit, the controller forcibly closes the water inlet valve; when the water level of the water storage container is lower than the preset safe water level lower limit, the controller forcibly closes the recharge valve; the safe water level upper limit is higher than the full water level, and the safe water level lower limit is lower than the low water level and higher than the water outlet position of the water storage container.

10. The system according to claim 6, characterized in that, The water storage container includes a first water storage container and a second water storage container. The first water storage container and the second water storage container alternately store water and refill water, with the storage and release phases staggered, so that at any given time, at least one of the water storage containers is in a refillable state. The end of the water diversion channel is divided into a first water diversion branch and a second water diversion branch; the first water diversion branch is connected to the inlet of the first water storage container, and a first water inlet valve is provided in the first water diversion branch; the second water diversion branch is connected to the inlet of the second water storage container, and a second water inlet valve is provided in the second water diversion branch. The front end of the reinjection pipeline is divided into a first reinjection branch and a second reinjection branch; the first reinjection branch is connected to the outlet of the first water storage container, and a first reinjection valve is installed in the first reinjection branch; the second reinjection branch is connected to the outlet of the second water storage container, and a second reinjection valve is installed in the second reinjection branch.

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