Groundwater circulation system and method

Abstract

The present application relates to the technical field of groundwater circulation well, and discloses a groundwater circulation system and method, the groundwater circulation system comprises a circulation well and a plurality of leakage pipelines, the circulation well has an upper screen section and a lower screen section connected in turn from top to bottom, the side wall of the upper screen section and the lower screen section is provided with first water-permeable holes, the plurality of leakage pipelines are connected around the upper screen section in a radial manner, the first end of the leakage pipeline is connected with the first water-permeable hole of the upper screen section, and the second end of the leakage pipeline extends to the side away from the upper screen section, wherein the leakage pipeline guides the water flow in the upper screen section to the aquifer, and then flows to the lower screen section to form a three-dimensional circulation of groundwater, and the groundwater circulation system and method can effectively expand the influence radius.

Description

Technical Field

[0001] This invention relates to the field of groundwater circulation well technology, and particularly to a groundwater circulation system and method. Background Technology

[0002] Groundwater refers to the fluid water contained in the soil and rock beneath the ground surface. As one of the most important freshwater resources in a country, it plays a vital role not only in urban water use but also in agricultural irrigation and industrial water supply. However, with rapid socio-economic development, human activities have led to a large influx of pollutants into groundwater, causing severe pollution. These pollutants accumulate through various processes, ultimately posing a significant threat to human health. Therefore, groundwater remediation is urgently needed.

[0003] Groundwater circulation well technology uses direct pumping (mechanical pumps) or stripping to drive groundwater to form a three-dimensional circulation around the well, increasing the radius of influence of the groundwater and simultaneously collecting pollutants from the aquifer into the well for in-situ remediation. Currently, the most common driving method is the mechanical pump method, which involves installing a lift pump inside the well. The pump's extraction action provides power for the groundwater circulation flow. The pumping method allows for control of the pumped water flow rate, thus effectively controlling the circulation speed. Circulation wells operate in two modes based on the direction of circulation: forward circulation and reverse circulation. In forward circulation, water is extracted from the lower end of the well and injected from the upper end, creating a three-dimensional flow field from top to bottom. In reverse circulation, water is extracted from the upper end and injected from the lower end, causing the water to flow upwards in a swirling motion from the lower screen section. Groundwater circulation well technology offers advantages such as small footprint, high remediation efficiency, and low cost. It can also be combined with other remediation technologies such as chemical oxidation, bioremediation, and vapor extraction to achieve simultaneous removal of non-aqueous liquids and some inorganic substances, thus demonstrating broad application prospects.

[0004] However, research on groundwater circulation well technology in my country started relatively late. Currently, there are only two engineering examples in the country, and the technology is still in the research stage. Complete sets of equipment are also lacking. Groundwater circulation well technology has high requirements for site hydrogeological conditions. Groundwater aquifers are mainly composed of multiple layers of heterogeneous media with different properties. Poorly permeable aquifers can lead to an excessively small radius of influence for the circulation well, and may even cause the well to malfunction. Currently, the radius of influence of a single circulation well is mostly around 25 meters, which is insufficient for large-scale hydraulic control. Therefore, how to expand the radius of influence of circulation wells is a key technical bottleneck that urgently needs to be overcome in groundwater circulation well technology.

[0005] Therefore, many technologies nowadays expand the influence radius of circulating wells by increasing the density of well clusters. However, such technologies are complex to operate and can cause some disturbance to underground aquifers. For example, Chinese patent CN114278271A discloses a composite circulating well system and its usage method. This circulating well system includes a main circulating well and a directional horizontal well group. By adjusting the valves on the surface, the circulation mode of the circulating well is changed, thereby increasing the water level difference between the upper and lower aquifers, solving the problem of unbalanced injection and extraction in traditional circulating wells, and increasing the hydrodynamic control area of ​​the circulating well. However, this system has a complex structure, requiring the installation of horizontal well groups in both the upper and lower aquifers, which may cause disturbance to deep aquifers. At the same time, several valves need to be installed on the surface, and the circulation of the circulating well is controlled by adjusting the opening and closing of different valves, making the operation complex. Moreover, the purpose of this patent is mainly focused on solving the problem of unbalanced injection and extraction in traditional circulating wells, and the effect on expanding the influence radius of the circulating well is relatively small.

[0006] However, current technologies for expanding the radius of influence of circulating wells have some drawbacks. For example, the drawback of constructing a multi-circulation well system is that it occupies a large area, causes significant disturbance to the formation, and is complex to install. Multi-screen circulating wells increase the number of screens on the basis of the original circulating well, and a circulating flow field is formed between adjacent screens. Thus, increasing the number of screens can form multiple circulating flow fields, thereby increasing the area of ​​influence. However, the radius of influence of circulating wells is not significantly expanded compared to dual-screen circulating wells. Summary of the Invention

[0007] To solve the above-mentioned technical problems, or at least partially solve them, this disclosure provides a groundwater circulation system and method that can effectively expand the radius of influence.

[0008] This disclosure provides a groundwater circulation system, including: a circulation well, the circulation well having an upper screen section and a lower screen section connected sequentially from top to bottom, the upper screen section and the lower screen section being spaced apart, and both the upper screen section and the lower screen section having first permeable holes on their sidewalls, and further including:

[0009] Multiple overflow pipes are radially connected around the upper screen section. The first end of the overflow pipe is connected to the first permeable hole of the upper screen section, and the second end of the overflow pipe extends away from the upper screen section. The overflow pipes guide the water flow in the upper screen section to the aquifer, and then flow to the lower screen section to form a three-dimensional circulation of groundwater.

[0010] Optionally, the upper screen section has a first side and a second side, wherein the aquifer permeability coefficient of the first side is lower than that of the aquifer permeability coefficient of the second side, and the layout density of the overflow pipes on the first side of the upper screen section is higher than that of the overflow pipes on the second side of the upper screen section.

[0011] Optionally, a monitoring subsystem is installed around the circulation well. The monitoring subsystem monitors whether groundwater from the three-dimensional circulation of groundwater enters the monitoring subsystem, thereby monitoring the influence radius of the circulation well.

[0012] Optionally, the monitoring subsystem can be located 10 to 40 meters away from the circulation well.

[0013] Optionally, the monitoring subsystem includes:

[0014] Multiple monitoring wells surround the circulation well, with the monitoring wells parallel to the circulation well and 10-40 meters away from it;

[0015] The monitoring unit is installed in the monitoring well and is used to monitor whether groundwater enters the monitoring well from the three-dimensional circulation of groundwater.

[0016] Optionally, the lower pipe wall of the monitoring well is provided with a screen section, and the side wall of the screen section has a second water permeable hole. Groundwater enters the monitoring well through the second water permeable hole, and the screen section is connected to a monitoring unit.

[0017] Optionally, the monitoring unit is connected to a display unit, which is used to display the data monitored by the monitoring unit.

[0018] Another aspect of this disclosure provides a groundwater circulation method, comprising:

[0019] Based on the hydrogeological conditions of groundwater, the number and location of circulation wells are determined. Each circulation well has an upper screen section and a lower screen section connected from top to bottom. A first permeable hole is opened on the side wall of both the upper and lower screen sections.

[0020] Multiple overflow pipes are installed around the upper screen section. The first end of the overflow pipe is connected to the first permeable hole of the upper screen section, and the second end of the overflow pipe extends away from the upper screen section. The overflow pipes guide the water flow in the upper screen section to the aquifer, and then flow to the lower screen section to form a three-dimensional circulation of groundwater.

[0021] Optionally, the crossflow pipeline can be arranged according to engineering requirements and the target of expanding the influence radius of the circulation well.

[0022] Optionally, a monitoring subsystem can be installed around the circulation well to monitor the radius of influence of the circulation well.

[0023] The technical solution provided in this disclosure has the following advantages compared with the prior art:

[0024] The groundwater circulation system and method provided in this disclosure utilize a bypass-flow circulation well influence radius expansion technology. The bypass-flow method involves installing a bypass pipe at the first permeable hole in the upper screen section of the circulation well. This causes groundwater flowing out of the upper screen section to first pass through the bypass pipe before entering the aquifer, still forming a three-dimensional groundwater flow field from top to bottom. However, the water flow experiences minimal velocity loss when passing through the bypass pipe, and after exiting the bypass pipe, it can still diffuse with the initial velocity it entered, thus reaching a greater distance. Therefore, the influence radius is effectively expanded, preventing groundwater from being blocked directly through aquifers with low permeability, which would otherwise lead to water loss. It cannot diffuse further, and the installation of the overflow pipe can be adjusted according to the specific engineering requirements to achieve different effects of expanding the radius of influence. Moreover, the overflow pipe is easy to install and causes little disturbance to the formation. In addition, the hydrogeological conditions of different formations vary greatly, and the influence range of the circulation well can be adjusted by changing the number and length of the overflow pipe, thus effectively increasing the influence radius of the circulation well. Therefore, this disclosure has strong applicability and can not only expand the lateral influence radius of the circulation well, but also change the vertical influence range of the circulation well by adjusting the burial depth of the overflow pipe, thereby achieving the expansion effect from multiple aspects. Attached Figure Description

[0025] Figure 1 A schematic diagram of the structure of an existing groundwater circulation well;

[0026] Figure 2 This is a schematic diagram of the structure of a groundwater circulation system provided in an embodiment of the present disclosure;

[0027] Figure 3 is a schematic diagram of a model with overflow pipes of different lengths installed;

[0028] Figure 4 shows a schematic diagram of the different burial depths of the crossflow pipeline with different upper screen section lengths.

[0029] Figure 5 is a schematic diagram of a model with different numbers of overflow pipes installed at the same horizontal height;

[0030] Figure 6 is a schematic diagram of a crossflow pipeline with different arrangement densities;

[0031] Figure 7 Figure showing the effect radius of circulation wells with different numbers of overflow pipes installed;

[0032] Figure 8 The diagram shows the effect radius of circulation wells with different overflow pipe lengths.

[0033] Explanation of reference numerals in the attached figures:

[0034] 1-Circulation well, 2-Overflow pipeline, 3-Monitoring well, 11-Main well cover, 12-Circulating water pump, 13-Injection pipe, 14-Upper screen section, 15-Isolator, 16-Pumping pipe, 17-Lower screen section, 18-Groundwater flow field, 31-Display unit, 32-Screen section, 33-Monitoring unit. Detailed Implementation

[0035] The following detailed description of a specific embodiment of the present invention is provided in conjunction with the accompanying drawings. However, it should be understood that the scope of protection of the present invention is not limited to the specific embodiment.

[0036] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the technical solution of this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0037] Research on groundwater circulation well technology in my country started relatively late. Currently, there are only two engineering examples in the country, and it is still in the research stage. Complete sets of equipment are also lacking. Groundwater circulation well technology has high requirements for site hydrogeological conditions. Groundwater aquifers are mainly composed of multiple layers of heterogeneous media with different properties. Aquifers with poor permeability will result in a small radius of influence for the circulation well, and may even cause the circulation well to fail to operate normally. To more clearly illustrate the specific solutions of the embodiments disclosed in this disclosure, a systematic introduction to groundwater circulation wells is first given, which can be found in [reference missing]. Figure 1The groundwater circulation well 1 is a mechanical pump-type circulation well, constructed by nesting inner and outer well pipes. It includes a main well cover 11, a circulating water pump 12, an injection pipe 13, and a pumping pipe 16. The well body has an upper screen section 14 and a lower screen section 17, each with a first permeable hole. Water can only flow through these first permeable holes; the rest are solid pipes. A barrier 15 is located between the two screen sections. The lower end of the pumping pipe 16 extends through a pre-drilled hole in the barrier 15 to the lower screen section 17. The lower end of the injection pipe 13 is located at the upper screen section 14. The upper ends of the pumping pipe 16 and the injection pipe 13 extend to the ground and connect to the circulating water pump 12. The groundwater circulation well 1 is located within the soil of the application site. Water flows directly into the aquifer through the first permeable hole in the upper screen section 14, flowing down to the lower screen section 17 to form a three-dimensional groundwater flow field. This accelerates groundwater circulation, carrying pollutants into the well for remediation. Currently, the influence radius of a single circulation well is mostly around 25m, which cannot achieve large-scale hydraulic control. Therefore, how to expand the influence radius of circulation wells is a key technical bottleneck that urgently needs to be overcome in the current groundwater circulation well technology.

[0038] Therefore, many technologies nowadays expand the influence radius of circulating wells by increasing the density of well clusters. However, such technologies are complex to operate and can cause some disturbance to underground aquifers. For example, Chinese patent CN114278271A discloses a composite circulating well system and its usage method. This circulating well system includes a main circulating well and a directional horizontal well group. By adjusting the valves on the surface, the circulation mode of the circulating well is changed, thereby increasing the water level difference between the upper and lower aquifers, solving the problem of unbalanced injection and extraction in traditional circulating wells, and increasing the hydrodynamic control area of ​​the circulating well. However, this system has a complex structure, requiring the installation of horizontal well groups in both the upper and lower aquifers, which may cause disturbance to deep aquifers. At the same time, several valves need to be installed on the surface, and the circulation of the circulating well is controlled by adjusting the opening and closing of different valves, making the operation complex. Moreover, the purpose of this patent is mainly focused on solving the problem of unbalanced injection and extraction in traditional circulating wells, and the effect on expanding the influence radius of the circulating well is relatively small.

[0039] However, current technologies for expanding the radius of influence of circulating wells have some drawbacks. For example, the drawback of constructing a multi-circulation well system is that it occupies a large area, causes significant disturbance to the formation, and is complex to install. Multi-screen circulating wells increase the number of screens on the basis of the original circulating well, and a circulating flow field is formed between adjacent screens. Thus, increasing the number of screens can form multiple circulating flow fields, thereby increasing the area of ​​influence. However, the radius of influence of circulating wells is not significantly expanded compared to dual-screen circulating wells.

[0040] Therefore, this disclosure provides a groundwater circulation system and method that can expand the influence radius of the circulation well.

[0041] At least one embodiment of this disclosure provides a groundwater circulation system, including: a circulation well and multiple overflow pipes. The circulation well has an upper screen section and a lower screen section connected sequentially from top to bottom, with the upper screen section and the lower screen section spaced apart. The sidewalls of both the upper screen section and the lower screen section have first permeable holes. The multiple overflow pipes are radially connected around the upper screen section. The first end of the overflow pipe is connected to the first permeable hole of the upper screen section, and the second end of the overflow pipe extends away from the upper screen section. The overflow pipes guide the water flow in the upper screen section to the aquifer, and then flow to the lower screen section to form a three-dimensional circulation of groundwater.

[0042] In the groundwater circulation system provided in the above-described embodiments, the influence radius expansion technology of the bypass circulation well is achieved by installing a bypass pipe at the first permeable hole of the upper screen section of the circulation well. This causes the groundwater flowing out of the upper screen section to first pass through the bypass pipe before entering the aquifer, still forming a three-dimensional groundwater flow field from top to bottom. However, there is basically no velocity loss when the water flows through the bypass pipe, and after flowing out of the bypass pipe, it can still diffuse with the initial velocity when entering the bypass pipe, thus being able to be transmitted to a farther distance. Therefore, the influence radius is effectively expanded.

[0043] The present disclosure will now be described through several specific embodiments. To keep the following description of the embodiments of the present disclosure clear and concise, detailed descriptions of known functions and components may be omitted. When any component of an embodiment of the present disclosure appears in more than one drawing, the component may be represented by the same reference numerals in each drawing.

[0044] Figure 2 This is a schematic diagram of the structure of a groundwater circulation system provided in an embodiment of this disclosure.

[0045] like Figure 2 As shown, this embodiment of the present disclosure provides a groundwater circulation system, including: a circulation well 1, the circulation well 1 having an upper screen section 14 and a lower screen section 17 connected sequentially from top to bottom, the upper screen section 14 and the lower screen section 17 being spaced apart, and the sidewalls of the upper screen section 14 and the lower screen section 17 both having first permeable holes; and further including: multiple overflow pipes 2, which are radially connected around the upper screen section 14, the first end of the overflow pipe 2 being connected to the first permeable hole of the upper screen section 14, and the second end of the overflow pipe 2 extending away from the upper screen section 14, wherein the overflow pipes 2 guide the water flow in the upper screen section 14 to the aquifer, and then flow down to the lower screen section 17 to form a three-dimensional circulation of groundwater. The overflow pipes are arranged around the upper screen section, and the lengths of the overflow pipes are different, so that they can affect the aquifer at different distances from the groundwater circulation well.

[0046] It should be understood that this disclosure is based on existing... Figure 1An overflow pipe is added to the existing circulation well. This overflow pipe is a water pipe buried around the circulation well. It can be installed perpendicular to the circulation well or at a certain angle. The overflow pipe simply needs to be connected to the first permeable hole of the upper screen section of the circulation well, allowing water flowing out of the upper screen section to enter the overflow pipe. When the circulation well is in positive circulation mode (downward pumping and upward injection), the water level at the upper screen section rises. Without the overflow pipe, the water flows directly into the aquifer through the first permeable hole of the upper screen section, flowing down to the lower screen section to form a three-dimensional groundwater flow field. This disclosure installs a bypass pipe at the first permeable hole of the upper screen section. The bypass pipe forms a priority channel for water flow. Water first passes through the bypass pipe before entering the aquifer, still forming a three-dimensional groundwater flow field from top to bottom. However, the water experiences virtually no velocity loss when passing through the bypass pipe, and after exiting the bypass pipe, it can still diffuse with the initial velocity it entered, thus reaching a greater distance. Therefore, the radius of influence is effectively expanded, preventing groundwater from being blocked directly through aquifers with low permeability, which would prevent the water from diffusing further. Furthermore, the bypass pipe is securely installed... The installation of the overflow pipe can be adjusted according to the specific needs of the project to achieve different effects on the radius of influence. The overflow pipe is easy to install and causes minimal disturbance to the formation. Furthermore, the hydrogeological conditions of different formations vary greatly; the influence range of the circulation well can be adjusted by changing the number and length of the overflow pipes, effectively increasing the radius of influence. Therefore, this disclosure has strong applicability. It can not only expand the lateral radius of influence of the circulation well, but also change the vertical radius of influence by adjusting the burial depth of the overflow pipe, thus achieving the expansion effect from multiple aspects. The material selection for the overflow pipe is diverse. For example, stainless steel can be used, as its surface is not easily rusted, it has high strength, and it is not easily deformed; PE can also be used, as it has good chemical resistance, flexibility, and is easy to install; and PVC, a widely used material, is another option. PVC is a high-molecular-weight material, and PVC pipes are low in cost and have a wide range of applications. When selecting the material for overflow pipes, the choice should be based on the actual needs of the project. For example, in groundwater, considering the economics of repair and whether the chemical remediation agent will react with the overflow pipe, PE or PVC overflow pipes can be selected.

[0047] In practice, different sides of the circulating well have different aquifer permeability, requiring adjustments to the flow field intensity based on these varying aquifer permeability. Therefore, the upper screen section 14 has a first side and a second side, where the aquifer permeability coefficient on the first side is lower than that on the second side. Consequently, the density of the overflow pipes 2 on the first side of the upper screen section 14 is higher than that on the second side. It should be noted that the terms "first side" and "second side" in this disclosure do not refer to specific locations, but rather to different orientations of the upper screen section. To illustrate the different aquifer permeability coefficients at different orientations, it should be understood that different circulating wells are located in different environments. Therefore, there are not only two different aquifer permeability coefficients at different orientations around the upper screen section. Overflow pipes with different permeability densities can be installed circumferentially according to these different permeability coefficients. Since the aquifer permeability coefficient on the first side is lower, a stronger flow field intensity is required; therefore, the overflow pipe density on the first side is higher than that on the second side. The density of these overflow pipes can be referenced here. Figure 2 The arrangement of the circulating wells along their depth direction. If a specific flow field influence is required on the upper and lower regions of the aquifer, the length of the upper screen section can be increased. A crossflow pipe is installed below the extended upper screen section on the left side of the circulating well, thus influencing the lower part of the aquifer. Simultaneously, a crossflow pipe 2 is installed above the extended upper screen section 14 on the right side of the circulating well, further influencing the upper part of the aquifer. Both the left and right sides here have... Figure 2 Based on the orientation in the middle. Turn on the circulating water pump 12, pump water from the pumping pipe 16 and inject it through the water injection pipe 13. The water level at the upper screen section 14 rises, and the water flows through the upper screen section 14 into the overflow pipe 2. After passing through the overflow pipe 2, it flows through the aquifer and down to the lower screen section 17, thus forming the groundwater flow field 18.

[0048] It should be understood that, Figure 2The overflow pipes 2 shown are arranged in multiple rows along the axial direction of the upper screen section 14. The extension length of the overflow pipes 2 gradually shortens from the end furthest from the lower screen section 17 to the end closer to the lower screen section 17. This does not mean that the overflow pipes installed in the circulation well need to be arranged in a gradually decreasing length from top to bottom. It only shows that the length of the overflow pipes is not necessarily a single length. The actual installation length can be installed according to the required circulation influence radius target. The circulation well influence radius refers to the farthest distance from the boundary of the circulation zone to the axis of the circulation well. The overflow pipes expand the circulation well influence radius by forming a priority channel for the water flow in the upper screen section. The water flow first passes through the unobstructed overflow pipes, and after flowing out of the overflow pipes, it enters the aquifer to form a circulation flow field. Therefore, the length of the overflow pipes will affect the effect of expanding the influence radius. Therefore, the radius of influence of the circulation well can be adjusted by installing overflow pipes of different lengths. The circulation flow field formed by shorter overflow pipes mainly affects the aquifer near the circulation well, while longer overflow pipes can allow groundwater to circulate to a greater distance, thereby expanding the circulation radius. Thus, installing overflow pipes of different lengths can affect the circulation well from near to far.

[0049] In order to monitor whether the influence radius of the circulation well meets the planned requirements, in some embodiments of this disclosure, a monitoring subsystem is set up around the circulation well 1. The monitoring subsystem monitors whether groundwater enters the monitoring subsystem from the three-dimensional circulation of groundwater, thereby monitoring the influence radius of the circulation well 1. That is to say, if the monitoring subsystem detects groundwater, it means that the distance between the monitoring subsystem and the circulation well is the influence radius of the circulation well. If groundwater is not detected, the length of the overflow pipe needs to be adjusted until the monitoring subsystem detects groundwater.

[0050] Since the influence radius of circulation wells is mostly 10m-40m, the monitoring subsystem is deployed at a distance of 10m-40m from circulation well 1. It needs to be coordinated with the influence radius of circulation well. For example, if the influence radius of circulation well needs to be designed to be 15m in a certain place, the monitoring subsystem should be deployed at a distance of 15m from circulation well. If the monitoring subsystem detects groundwater, it means that the length of the overflow pipe is appropriate at this time.

[0051] Specifically, the monitoring subsystem includes: multiple monitoring wells 3 and monitoring units 33. The multiple monitoring wells 3 surround the circulation well 1. The monitoring wells 3 are parallel to the circulation well 1 and are 10-40 meters away from the circulation well. The monitoring units 33 are set in the monitoring wells 3 and are used to monitor whether groundwater enters the monitoring well 3 from the three-dimensional circulation of groundwater.

[0052] It should be noted that whether the depths of the monitoring well and the circulation well are the same does not need to be considered. The monitoring unit only needs to be a component that can detect whether there is water flow, including but not limited to water level sensors.

[0053] As one implementation method, the lower pipe wall of the monitoring well 3 is provided with a screen section 32, and the side wall of the screen section 32 has a second water permeable hole. Groundwater enters the monitoring well 3 through the second water permeable hole, and the screen section 32 is connected to a monitoring unit 33.

[0054] The monitoring unit is located inside the monitoring well. The water level sensor isn't necessarily required to be in the middle of the screen section; it's just that groundwater enters through the second permeable hole. Positioning the sensor in the middle allows for faster detection. When a three-dimensional circulation of groundwater forms around the circulation well, if groundwater enters the monitoring well through the second permeable hole, the water level sensor will detect a rise in the water level. This indicates that the radius of influence of the circulation well is the distance between the two points. Therefore, as long as water enters the monitoring well, it can function effectively.

[0055] For ease of observation, the monitoring unit 33 is connected to a display unit 31, which is used to display the data monitored by the monitoring unit 33. The data monitored by the monitoring unit is transmitted to the display unit and displayed thereon, thereby allowing for real-time observation of the groundwater circulation.

[0056] This disclosure also provides a groundwater circulation method, including:

[0057] Step 1: Based on the hydrogeological conditions of the groundwater, determine the number and location of the circulation wells 1. The circulation well 1 has an upper screen section 14 and a lower screen section 17 connected from top to bottom. First permeable holes are opened on the side walls of the upper screen section 14 and the lower screen section 17.

[0058] Step 2: Install multiple overflow pipes 2 around the upper screen section 14. The first end of the overflow pipe 2 is connected to the first water permeable hole of the upper screen section 14, and the second end of the overflow pipe 2 extends away from the upper screen section 14. The overflow pipe 2 guides the water flow in the upper screen section 14 to the aquifer, and then flows to the lower screen section 17 to form a three-dimensional circulation of groundwater.

[0059] The installation of the overflow pipe is to expand the influence radius of the circulation well. Before the overflow pipe was installed, groundwater drawn from the bottom of the circulation well was injected into the upper screen section, causing the water level in the upper screen section to rise. The groundwater then flowed out from the first permeable hole of the upper screen section at an initial velocity, directly passing through the aquifer and forming a three-dimensional flow field towards the lower screen section. However, due to the low permeability coefficient of the aquifer, the diffusion of groundwater was hindered, resulting in a small influence radius for the circulation well. After the overflow pipe was installed, some of the groundwater flowing out from the first permeable hole of the upper screen section could enter the overflow pipe. Since the overflow pipe is a hollow water pipe, the transmission of groundwater within it was unimpeded. The groundwater then flowed out of the overflow pipe outlet at the same initial velocity as when it flowed out from the upper screen section, passing through the aquifer and forming a three-dimensional flow field. Specifically, regarding the distance between the outlet of the bypass pipe and the circulation well, before the installation of the bypass pipe, the water flow velocity at this location was low due to the obstruction of the aquifer. After the installation of the bypass pipe, the velocity at this location is comparable to the groundwater flow velocity from the first permeable hole in the upper screen section. Therefore, after installing the bypass pipe, the water flow can be transmitted to a greater distance, thus expanding the influence radius of the circulation well. The influence radius of the circulation well is expanded by changing the following relevant parameters of the bypass pipe:

[0060] The radius of influence of a circulating well refers to the farthest distance from the boundary of the circulating zone to the axis of the circulating well. Expanding the radius of influence of a circulating well through a bypass pipe creates a priority channel for water flow in the upper screen section. Water first passes through the unobstructed bypass pipe, then flows out and enters the aquifer, forming a circulating flow field. Therefore, the length of the bypass pipe affects the expansion of the radius of influence. Thus, the radius of influence of the circulating well can be adjusted by installing bypass pipes of different lengths. A shorter bypass pipe mainly affects the aquifer near the circulating well, while a longer bypass pipe allows groundwater to circulate to a greater distance, achieving the effect of expanding the circulation radius. Therefore, installing bypass pipes of varying lengths can affect the area from near to far of the circulating well.

[0061] The overflow pipe can not only expand the radius of influence of the circulation well, i.e., increase the lateral influence range of the circulation well, but also affect the vertical influence range of the circulation well. This vertical influence range can be altered by increasing the length of the upper screen section and simultaneously changing the burial depth of the overflow pipe within that section. Installing the overflow pipe near the upper screen section can influence the upper part of the aquifer, while installing it below the upper screen section can treat pollutants in the lower part of the aquifer. Therefore, in specific engineering cases where it is necessary to specifically influence the flow field at the upper and lower ends of the aquifer, the length of the upper screen section of the circulation well can be appropriately increased before installing the overflow pipe to expand the vertical influence range.

[0062] The flow field intensity of the circulation well can be adjusted by changing the diameter of the bypass pipes and the number of bypass pipes installed at the same height on the screen section of the circulation well. Since the circulation well is a three-dimensional circular pipe, the resulting flow field is three-dimensional. Therefore, at least one bypass pipe should be installed in each of the four cardinal directions (north, south, east, and west) to enhance the flow field intensity around the circulation well. The more bypass pipes there are, the greater the flow rate of water that can preferentially pass through them, meaning more groundwater can flow through the bypass pipes before entering the aquifer. This allows more groundwater to initially diffuse out of the bypass pipe outlets, resulting in a stronger groundwater flow field. However, the number of bypass pipes should not be excessive, as this not only complicates installation but also significantly disturbs the groundwater aquifer. The diameter of the bypass pipe has the same amplification effect as the number of bypass pipes; the longer the bypass pipe, the more significant the amplification effect on the circulation well's radius of influence. However, the diameter should not be too large. The specific number and diameter of the bypass pipes should be determined based on the required circulation flow field intensity for the actual project.

[0063] The density of overflow pipes refers to the number installed at different heights in the upper screen section. Changing the density of overflow pipes can alter the circulation intensity of the groundwater flow field in different areas. Groundwater aquifer permeability coefficients are typically unevenly distributed. When an aquifer with a low permeability coefficient exists, a higher flow velocity is required for groundwater to pass through it. Therefore, changing the density of overflow pipes can make the aquifer circulation more uniform. Thus, when dealing with heterogeneous groundwater aquifers, the density of overflow pipes should be determined based on the aquifer's properties. For example, for aquifers with low permeability coefficients, a denser overflow pipe density will result in a stronger groundwater circulation field, thus scouring the aquifer. Conversely, if the aquifer has a high permeability coefficient, an appropriate number of overflow pipes should be installed considering economic factors for repair.

[0064] Specifically, a monitoring subsystem is set up around circulation well 1. The monitoring subsystem is used to monitor the influence radius of circulation well 1. The main circulation well is set up inside the soil of the site. The monitoring subsystem is deployed at a distance of 10-40m from the circulation well.

[0065] The groundwater circulation method in some embodiments of this disclosure includes the following steps:

[0066] Step 1: Based on the hydrogeological conditions of groundwater, conduct reasonable well placement;

[0067] A detailed hydrogeological survey was conducted at the application site to determine the site's hydrogeological conditions and pollution status. Based on the scope of the application site and the nature of the pollutants, the number and location of groundwater circulation well 1 and monitoring well 3 were determined.

[0068] Step 2: Install the overflow pipe 2, and connect the inlet to the first permeable hole of the upper screen section 14 of the circulation well 1;

[0069] The technical parameters of the overflow pipe 2 are determined based on the hydrogeological conditions of the application site and the expected effects. Four main technical parameters need to be determined. The length of the overflow pipe 2 has a wide selection range, and different lengths have different effects on increasing the radius of influence of the circulation well. The installation methods of overflow pipe 2 of different lengths are shown in Figure 3. Figure 3a The length of the overflow pipe is 5m. Figure 3b The length of the overflow pipe is 10m. Figure 3c The length of the overflow pipe is 15m, and the installation length can be determined according to the target radius of influence expansion. The properties of the underground aquifers vary, and the distribution of pollutants differs. Therefore, the burial depth of the overflow pipe 2 needs to be determined based on the vertical distribution of pollutants at the site. Figure 4 shows models with different burial depths of the overflow pipe for different upper screen section lengths. Figure 4a When the length of the upper and middle screen sections is 3m, the overflow pipes are installed at distances of 0.75m, 1.5m, and 2.25m from the bottom of the upper screen section, respectively. Figure 4b When the length of the upper and middle screen sections is 4m, the overflow pipes are installed at distances of 0.5m, 2m, and 3.5m from the bottom of the upper screen section, respectively. Figure 4c When the length of the upper and middle screen sections is 5m, the overflow pipes are installed at distances of 0.5m, 2m, and 3.5m from the bottom of the upper screen section, respectively. Figure 5 shows different numbers of overflow pipes installed at the same horizontal height. Figure 5a There are 4 overflow pipes in the middle. Figure 5b There are 8 overflow pipes in the middle. Figure 5c The system includes 12 overflow pipes. The specific number of overflow pipes 2 can be determined based on the extent of contamination at the site. A wider contamination area requires a larger radius of influence, thus necessitating more overflow pipes 2. Conversely, a smaller contamination area can achieve the same result economically with fewer overflow pipes. The density of the overflow pipes 2 is determined based on the properties of the aquifer at the application site, as well as the properties and distribution of the pollutants. If the aquifer has a low permeability coefficient, a stronger circulation intensity is required, thus a denser density is sufficient. Conversely, if the aquifer has a high permeability coefficient, a sparser density can be installed considering ease of installation and economy. The specific installation methods for overflow pipes 2 with different density are shown in Figure 6. Figure 6a The overflow pipes in the middle are arranged in three longitudinal directions. Figure 6b The overflow pipes in the middle are arranged in four longitudinal directions. Figure 6c The overflow pipes in the middle are arranged in a longitudinal direction, consisting of 5 pipes.

[0070] Step 3: Start the circulating water pump 12 to activate the positive circulation mode of bottom pumping and top injection;

[0071] Specifically, the circulating water pump 12 is started to draw groundwater from the lower screen section 17 and inject it into the upper screen section 14. The water level in the upper screen section 14 rises, and part of the water flows through the first permeable hole of the upper screen section 14 into the connected overflow pipe 2. Part of the water flows into the aquifer after passing through the first permeable hole, and then flows into the lower screen section 17 under the action of the circulating well 1, thus forming a three-dimensional groundwater flow field 18 from top to bottom, which can bring pollutants in the aquifer into the circulating well 1 for in-situ remediation.

[0072] Step 4: Start monitoring well 3 to monitor the influence radius of groundwater circulation well 1;

[0073] The groundwater level changes are monitored in real time by a water level sensor in monitoring well 3, and the data is transmitted to display unit 31. Therefore, the amplification effect of the influence radius of the groundwater circulation well can be analyzed.

[0074] The following examples illustrate specific application scenarios of the groundwater circulation system disclosed herein.

[0075] Example 1

[0076] The number of crossflow pipes installed at the same height in the upper screen section affects the flow field intensity of the circulation well. The groundwater flow field formed by the circulation well is a three-dimensional circulating flow field. Therefore, the crossflow pipes need to be installed in different directions at the same height in the upper screen section.

[0077] This embodiment uses COMSOL Multiphysics finite element simulation software to study the effect of the number of overflow pipes on the radius expansion of the circulation well. The established study site is a cuboid with a length of 70m, a width of 40m, and a height of 30m. The site has no rainfall or evaporation, and it is assumed that the initial groundwater level is 3m below the surface. The porosity of the site is 0.3, and the hydraulic conductivity is 2.94 × 10⁻⁶. -4 The circulation well is located at the center of the site, with a radius of 0.8m and a height of 25m. The top of the upper screen section is located 4m above the ground and is 3m long. The bottom of the lower screen section is located 5m from the bottom of the circulation well and is 3m long. The inlet of the overflow pipe is connected to the first permeable hole of the upper screen section, and the diameter of both is set to 0.1m. When the positive circulation mode of bottom pumping and top injection is activated, the pumping and injection flow rates are both set to 0.4kg / s.

[0078] This embodiment selects three numbers of overflow pipes: 4, 8, and 12 overflow pipes, with an overflow pipe length of 5m. The inlet of the overflow pipe is connected to the permeable hole in the middle of the upper screen section. The constructed circulation well model is shown in Figure 5. The effect of expanding the circulation well's radius of influence is compared under the three numbers. The radius of influence of the circulation well refers to the farthest distance from the boundary of the circulation zone to the axis of the circulation well. Therefore, the Darcy velocity of the groundwater is observed at the cross-section at the center of the two screen sections, and a uniform Darcy velocity of 4×10⁻⁶ is selected. -8 m / s is the stationary reference velocity. The radius of the circulation is the Darcy velocity, which is 4 × 10⁻⁶ m / s. -8 Distance from the circulation well at m / s.

[0079] Figure 7 The Darcy velocity values ​​at different distances from the circulation well are obtained under different numbers of overflow pipes installed. When no overflow pipes are installed, the influence radius of the circulation well is 16m. When one overflow pipe is installed in each of the four directions (north, south, east, and west) of the screen section of the circulation well, the influence radius of the circulation well is slightly increased to 16.6m. When eight overflow pipes are installed at the screen section of the circulation well, the influence radius of the circulation well increases to 18.2m. When twelve overflow pipes are installed, the influence radius of the circulation well increases to 19.6m.

[0080] The installation of overflow pipes has an amplification effect on the radius of influence of the circulation well, and the amplification effect varies depending on the number of installations. The more installations, the more groundwater preferentially enters the overflow pipes, and therefore more groundwater can be transported to a greater range in the aquifer, thus having a stronger amplification effect on the radius of influence of the circulation well.

[0081] Example 2

[0082] The length of the overflow pipe has a certain impact on the amplification effect of the circulation well's radius of influence. This is because the longer the overflow pipe, the more unobstructed the groundwater can travel along the length of the overflow pipe before entering the aquifer.

[0083] This embodiment uses COMSOL Multiphysics finite element simulation software to study the effect of the number of overflow pipes on the radius expansion of the circulation well. The established study site is a cuboid with a length of 70m, a width of 40m, and a height of 30m. The site has no rainfall or evaporation, and it is assumed that the initial groundwater level is 3m below the surface. The porosity of the site is 0.3, and the hydraulic conductivity is 2.94 × 10⁻⁶. -4The circulation well is located at the center of the site, with a radius of 0.8m and a height of 25m. The top of the upper screen section is located 4m above the ground and is 3m long. The bottom of the lower screen section is located 5m from the bottom of the circulation well and is 3m long. The inlet of the overflow pipe is connected to the first permeable hole of the upper screen section, and the diameter of both is set to 0.1m. When the positive circulation mode of bottom pumping and top injection is activated, the pumping and injection flow rates are both set to 0.4kg / s.

[0084] In this embodiment, three overflow pipe lengths are selected: 5m, 10m, and 15m. Four overflow pipes are installed in the four cardinal directions (east, south, west, and north) of the upper screen section of the circulation well. The inlet of each overflow pipe is connected to the permeable hole in the middle of the upper screen section. The constructed circulation well model is shown in Figure 3. Figure 3a The length of the overflow pipe is 5m. Figure 3b The length of the overflow pipe is 10m. Figure 3c The length of the overflow pipe in the test was 15m. The effect of increasing the radius of influence of the circulation well was compared under three different lengths. The radius of influence of the circulation well refers to the farthest distance from the boundary of the circulation zone to the axis of the circulation well. Therefore, the Darcy velocity of the groundwater was observed at the cross-section located at the center of two screen sections, and a Darcy velocity of 4×10⁻⁶ was uniformly selected. -8 m / s is the stationary reference velocity. The radius of the circulation is the Darcy velocity, which is 4 × 10⁻⁶ m / s. -8 Distance from the circulation well at m / s.

[0085] Figure 8 The Darcy velocity values ​​at different distances from the circulation well are obtained under different overflow pipe lengths. When no overflow pipe is installed, the influence radius of the circulation well is 16m; when the overflow pipe length is 5m, the influence radius of the circulation well is slightly increased to 16.6m; when the overflow pipe length is 10m, the influence radius of the circulation well is increased to 18.8m; and when the overflow pipe length is 15m, the influence radius of the circulation well is increased to 23.4m.

[0086] As demonstrated in this embodiment, the length of the overflow pipe has a significant impact on the expansion of the circulation well's radius of influence. To understand this effect, ideally, due to the installation of a certain length of overflow pipe, groundwater can first travel a distance—the length of the overflow pipe—before entering the aquifer to form a three-dimensional groundwater flow field. In other words, the increased radius of influence is equal to the length of the overflow pipe. While the transmission of groundwater within the overflow pipe may still encounter resistance and other factors, preventing the achievement of the ideal expansion effect, the result remains that the longer the overflow pipe, the more significant the expansion of the circulation well's radius of influence.

[0087] The above-disclosed embodiments are merely a few specific examples of the present invention. However, the embodiments of the present invention are not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A groundwater circulation system, comprising a circulation well (1), the circulation well (1) having an upper screen section (14) and a lower screen section (17) connected sequentially from top to bottom, the upper screen section (14) and the lower screen section (17) being spaced apart, and both the upper screen section (14) and the lower screen section (17) having first permeable holes on their sidewalls, characterized in that, Also includes: Multiple overflow pipes (2) are radially connected around the upper screen section (14). The first end of the overflow pipe (2) is connected to the first permeable hole of the upper screen section (14), and the second end of the overflow pipe (2) extends away from the upper screen section (14). The overflow pipe (2) guides the water flow in the upper screen section (14) to the aquifer, and then flows to the lower screen section (17) to form a three-dimensional circulation of groundwater. There are multiple overflow pipes (2), and the upper screen section (14) has a first side and a second side. The aquifer permeability coefficient of the first side is lower than that of the aquifer permeability coefficient of the second side. The overflow pipe (2) located on the first side of the upper screen section (14) has a higher density than the overflow pipe (2) located on the second side of the upper screen section (14). The extension length of the overflow pipe (2) gradually shortens from the end away from the lower screen section (17) to the end closer to the lower screen section (17); A monitoring subsystem is provided around the circulation well (1). The monitoring subsystem monitors the radius of influence of the circulation well (1) by monitoring whether groundwater enters the monitoring subsystem from the three-dimensional circulation of groundwater. The monitoring subsystem is located 10-40 meters away from the circulation well (1); The monitoring subsystem includes: Multiple monitoring wells (3) surround the circulation well (1), the monitoring wells (3) are parallel to the circulation well (1), and the monitoring wells (3) are 10-40 meters away from the circulation well (1); A monitoring unit (33) is installed in the monitoring well (3). The monitoring unit (33) is used to monitor whether there is groundwater entering the monitoring well (3) from the three-dimensional circulation of groundwater. The lower pipe wall of the monitoring well (3) is provided with a screen section (32), and the side wall of the screen section (32) has a second water permeable hole. The groundwater enters the monitoring well (3) through the second water permeable hole. The screen section (32) is connected to the monitoring unit (33). When a three-dimensional circulation of groundwater is formed around the circulation well (1), if the groundwater enters the monitoring well (3) through the second permeable hole of the monitoring well (3), the monitoring unit (33) will sense the rise in the water level in the monitoring well, indicating that the influence radius of the circulation well (1) is the distance between the two.

2. The groundwater circulation system as described in claim 1, characterized in that, The monitoring unit (33) is connected to a display unit (31), which is used to display the data monitored by the monitoring unit (33).

3. A groundwater circulation method, based on the groundwater circulation system according to any one of claims 1 to 2, characterized in that, include: Based on the groundwater hydrogeological conditions, the number and location of the circulation wells (1) are determined. The circulation wells (1) have an upper screen section (14) and a lower screen section (17) connected sequentially from top to bottom. First permeable holes are opened on the side walls of the upper screen section (14) and the lower screen section (17). Multiple overflow pipes (2) are installed circumferentially on the upper screen section (14). The first end of the overflow pipe (2) is connected to the first water-permeable hole of the upper screen section (14), and the second end of the overflow pipe (2) extends away from the upper screen section (14). The overflow pipe (2) guides the water flow in the upper screen section (14) to the aquifer, and then flows to the lower screen section (17) to form a three-dimensional circulation of groundwater. The overflow pipeline (2) is arranged according to the engineering requirements and the target of expanding the influence radius of the circulation well.

4. The groundwater circulation method as described in claim 3, characterized in that, A monitoring subsystem is set up around the circulation well (1) to monitor the influence radius of the circulation well (1).

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