Multifunctional precipitation / recharge well and construction method thereof

Abstract

The present application relates to the technical field of building construction, and more particularly to a multifunctional dewatering / recharge well and a construction method thereof. The multifunctional dewatering / recharge well comprises an outer well, an annular inner well and an anchor head, wherein: the outer well is assembled by a plurality of outer well units, the outer well units are of three types, namely, a first outer well unit, a second outer well unit and a third outer well unit; the annular inner well is assembled by a plurality of annular inner well units, the annular inner well units are of two types, namely, a first annular inner well unit and a second annular inner well unit; the annular inner well is movably assembled in the outer well, and the well walls of the outer well and the annular inner well are both provided with openings; and the anchor head is located at the bottom of the outer well and is used for drilling into the soil. The present application can prevent well blockage failure, improve the quality and construction efficiency of the well, and reuse the well and the filling material, and has good economy and environmental protection.

Description

Technical Field

[0001] This invention relates to the field of building construction technology, and in particular to a multifunctional dewatering / recharge well and its construction method. Background Technology

[0002] In foundation pit engineering, dewatering / recharge wells are used to extract / recharge groundwater to regulate the groundwater level distribution within the construction area. Currently, dewatering / recharge well structures consist of a single well casing and surrounding filler. The construction method involves drilling the hole first, placing the well casing, and finally filling the gap between the well casing and the hole sidewall with filler. Furthermore, as temporary structures, dewatering / recharge wells are directly scrapped after the foundation pit construction is completed.

[0003] The structure and usage of the aforementioned precipitation / recharge wells result in the following drawbacks, such as... Figure 1 As shown:

[0004] One drawback is that the well filter media is prone to clogging, leading to ineffective dewatering or reinjection. This is mainly due to two factors: firstly, the presence of floating debris, air bubbles, and chemical precipitates in the water can clog the filter media, which cannot be replaced during use because it is located deep within the soil outside the well; secondly, when cement grout or concrete is filled into the side of the reinjection well (to prevent water seepage from the sidewalls), the grout can seep into the filter layer, causing blockage.

[0005] Disadvantage 2: Poor well quality and slow construction. Currently, methods such as forward and reverse circulation or percussion drilling are commonly used for well drilling. In the case of loose and weak formations, the well is prone to collapse and shrinkage. In addition, it is necessary to go through the process of drilling, well release, and filling. If it is urgent to drill a well to control the danger, the current well structure and construction methods are obviously inadequate.

[0006] Disadvantage 3: Well pipes and fillers cannot be recycled, resulting in poor economic and environmental performance. As the pit is excavated, the fillers are also removed, and the dewatering wells are also cut off in stages; while the recharge wells and fillers outside the pit are left in the soil after the entire foundation pit project is completed, resulting in waste.

[0007] To address the first drawback mentioned above, invention (CN 103510501 B) applies rubber airbags to conventional reinjection wells to prevent filter layer failure and reinjection water surge caused by well pipe disturbance, but it cannot solve the problem of reinjection well failure caused by filter material blockage. To address the second and third drawbacks mentioned above, the structures proposed by inventions (CN 115341565 A, CN 108149699 A, CN 113833000 A) allow for the sinking and retrieval of dewatering wells, but if the dewatering well needs to be buried deep or the soil is hard, construction becomes difficult. Furthermore, inventions (CN 115341565 A, CN 108149699 A) are not suitable for dewatering wells in pits that are cut off in sections during excavation, and inventions (CN 108149699 A, CN 113833000 A) cannot replace the filter material during use. In summary, existing patents have only addressed some of the drawbacks of current precipitation / recharge wells. Summary of the Invention

[0008] The main objective of this invention is to provide a multifunctional dewatering / recharge well and its construction method, which aims to prevent well blockage and failure, improve well quality and construction efficiency, and reuse wells and filling materials.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] A multi-functional precipitation / recharge well includes an outer well, an annular inner well, and an anchor head, wherein:

[0011] The outer well is assembled from multiple outer well units, and there are three types of outer well units: the first outer well unit, the second outer well unit, and the third outer well unit.

[0012] The annular inner well is assembled from multiple annular inner well units. There are two types of annular inner well units: a first annular inner well unit and a second annular inner well unit.

[0013] The annular inner well is movably assembled inside the outer well, and both the outer well and the annular inner well have openings in their walls;

[0014] The anchor head is located at the bottom of the outer well and is used for drilling into the soil.

[0015] A construction method for a multi-functional precipitation / recharge well includes the following steps:

[0016] S1. Assembly of the outer well, annular inner well, and anchor head, including:

[0017] S11. Determine the number of the first outer well units based on the soil hardness;

[0018] S12. Determine the number and installation location of the second outer well unit based on the depth and thickness of the aquifer intended for precipitation / recharge;

[0019] S13. Determine the number and location of the third outer well unit based on the second outer well unit;

[0020] S14. Determine the number of the first annular inner well unit based on the number of the second outer well unit, and determine the number of the second annular inner well unit based on the number of the second outer well unit, the number of the first outer well unit, and the number of the third outer well unit.

[0021] S15. Assemble all external well units to form an external well; install the anchor head at the bottom of the external well.

[0022] S16. The first annular inner well unit is pre-set with a filter screen and filled with filter material, and assembled with each annular inner well unit to form an annular inner well.

[0023] S2. The annular inner well is mechanically screwed into the outer well;

[0024] S3. Determine the installation location of the dewatering / recharge well according to the project requirements, and then screw the dewatering / recharge well into the soil to the specified depth by means of mechanical screwing.

[0025] S4. After the rainwater / recharge wells have been used, they shall be dismantled and recycled.

[0026] The beneficial effects of this invention are as follows:

[0027] 1. This invention solves the shortcomings of traditional dewatering / recharge wells, such as easy clogging of filter media, poor well quality, slow construction, and the inability to recycle well casing and filler. Unlike existing patents that only address certain defects of traditional dewatering / recharge wells, this invention has multiple functions. Moreover, the realization of these functions is not a simple superposition of existing patent innovations, but rather achieved through an original new dewatering / recharge well structure and its construction method.

[0028] 2. Addressing the problem of easy clogging of filter media and well failure in traditional dewatering / recharge wells, this invention places the filter media in a first annular inner well. This first annular inner well can be rotatably installed / removed from the outer well, thus preventing filter media clogging through periodic replacement / replacement. Furthermore, since this invention does not contain other fillers around the well, it avoids the filter layer failure caused by construction disturbances in traditional dewatering / recharge wells.

[0029] 3. In view of the problems of poor well quality and slow construction of traditional precipitation / recharge wells, the present invention sets an anchor head at the bottom of the outer well and sets a spiral anchor plate in the first outer well unit, so that the whole well can be quickly rotated and implanted into the soil, and can be applied to soft soil or hard soil with large burial depth.

[0030] 4. In response to the problems of traditional dewatering / recharge well pipes and fillers being unrecyclable and having poor economic and environmental performance, the present invention consists of an outer well composed of interconnected outer well units and an inner well composed of interconnected annular inner well units. Thus, the dewatering well can be dismantled and the corresponding outer and inner well units can be recycled as the excavation depth progresses. After the recharge well is used, it can be mechanically pulled out and recycled. At the same time, the filter material is also recycled along with the inner well unit.

[0031] 5. When the present invention is used for recharge, the first outer well unit can be installed on the side of the second outer well unit away from the anchor head. The presence of the spiral anchor plate of the first outer well unit can extend the seepage path, thereby suppressing the overflow of recharge water from the contact surface between the recharge well and the soil to a certain extent.

[0032] 6. The inner and outer wells of this invention are connected by threads, which can prevent groundwater from overflowing from the junction of the inner and outer wells. Attached Figure Description

[0033] Figure 1 Schematic diagrams of traditional pressure relief wells in plan view and cross-section (a-plan view of water intake, b-cross-section view of water intake);

[0034] Figure 2 This is a schematic diagram of the structure of a precipitation / recharge well according to an embodiment of the present invention;

[0035] Figure 3 This is a schematic diagram of the outer well unit of the precipitation / recharge well in an embodiment of the present invention;

[0036] Figure 4 This is a schematic diagram of the annular inner well unit of the precipitation / recharge well in an embodiment of the present invention;

[0037] Figure 5 This is a flowchart illustrating the construction method of a precipitation / recharge well according to an embodiment of the present invention;

[0038] Figure 6 These are schematic diagrams of the plan and cross-sectional water intake of the precipitation / recharge well according to an embodiment of the present invention (a-plan view of water intake, b-cross-sectional view of water intake).

[0039] Explanation of icon numbers:

[0040] 1 outer well, 11 first outer well unit, 12 second outer well unit, 13 third outer well unit, 14 first spiral pattern, 15 first connecting structure, 111 spiral anchor plate;

[0041] 2 anchor heads;

[0042] 3. Annular inner well, 31. First annular inner well unit, 32. Second annular inner well unit, 33. Second spiral pattern, 34. Second connecting structure, 311. Inner ring of the first annular inner well unit, 312. Outer ring of the first annular inner well unit;

[0043] 4. Filter media;

[0044] 5. Filter screen;

[0045] 6. Hanging lugs. Detailed Implementation

[0046] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0047] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0048] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0049] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this invention.

[0050] This invention proposes a multifunctional dewatering / recharge well and its construction method, which can prevent well blockage and failure, improve well quality and construction efficiency, and reuse wells and filling materials.

[0051] The solution of this application will be described below with specific embodiments.

[0052] Example

[0053] Please refer to Figures 2 to 4 The multi-functional precipitation / recharge well includes an outer well 1, an annular inner well 3, and an anchor head 2, wherein:

[0054] The outer well 1 is assembled from multiple outer well units, and there are three types of outer well units, namely the first outer well unit 11, the second outer well unit 12, and the third outer well unit 13;

[0055] The annular inner well 3 is assembled from multiple annular inner well units. There are two types of annular inner well units: a first annular inner well unit 31 and a second annular inner well unit 32.

[0056] The annular inner well 3 is movably assembled inside the outer well 1, and both the outer well 1 and the annular inner well 3 have openings in their walls;

[0057] The anchor head is located at the bottom of the outer well 1 and is used for drilling into the soil.

[0058] Specifically, such as Figure 3 As shown, the outer well of the multi-functional precipitation / recharge well:

[0059] The first outer well unit 11 is provided with a spiral anchor plate 111 on the outside, which is used to rotate and cut the soil and drive the well to sink.

[0060] The second outer well unit 12 has uniformly permeable holes on its side to allow groundwater to seep through it.

[0061] The third outer well unit 13 is a complete steel pipe used to extend the dewatering / recharge well;

[0062] The installation position of the second outer well unit 12 corresponds to the aquifer to be dewatered / recharged; the third outer well unit 13 is located between the second outer well unit side away from the anchor head and the ground surface, and between the second outer well unit side near the anchor head and the first outer well unit 11; thus, from top to bottom, the third outer well unit 13, the second outer well unit 12, the third outer well unit 13, and the first outer well unit 11 are connected in sequence to form an outer well, wherein the number of each outer well unit is selected according to the construction scenario.

[0063] Furthermore, the anchor head 2 is connected to the first outer well unit 11 at the bottom of the outer well.

[0064] Furthermore, each outer well unit has a first spiral pattern 14 on its inner side and a first connecting structure 15 (which can be an anchor bolt or other various methods) on its outer side. Each outer well unit can be connected to each other through the first connecting structure 15 to form the outer well. After the connection is completed, the first spiral pattern 14 on the inner side of each outer well unit can be smoothly connected and transitioned.

[0065] Specifically, such as Figure 4 As shown, the annular inner well of the multi-functional precipitation / recharge well:

[0066] The first annular inner well unit 31 has a hollow internal structure with one end open and the other end closed, and is used to fill the filter material 4. Its inner and outer rings, namely the inner ring 311 and the outer ring 312 of the first annular inner well unit, are evenly provided with water-permeable holes, so that groundwater can seep through the outer ring 312, the filter material 4, and the inner ring 311 of the first annular inner well unit in sequence. A filter screen 5 is laid inside to prevent the filter material 4 from being lost.

[0067] The second annular inner well unit 32 is a solid internal structure used to increase the overall rigidity of the dewatering / recharge well;

[0068] The first annular inner well unit 31 is located above the second annular inner well unit 32, and they are connected to form an annular inner well. The number of each annular inner well unit is selected according to the construction scenario.

[0069] Furthermore, each annular inner well unit is provided with a second spiral pattern 33 on its outer side, and each annular inner well unit has a second connecting structure 34 (which can be an anchor bolt or other various methods) near the well axis. Each annular inner well unit can be connected to each other through the second connecting structure 34 to form the annular inner well 3. After the connection is completed, the second spiral pattern 33 on the outer side of each annular inner well unit can be smoothly connected and transitioned.

[0070] Furthermore, the first spiral pattern 14 on the inner side of the outer well unit matches the second spiral pattern 33 on the outer side of the annular inner well unit. The annular inner well can be mechanically rotated into and out of the outer well, while also preventing groundwater from overflowing from the junction of the inner and outer wells.

[0071] Furthermore, before the dewatering / recharge well construction enters the soil, the second annular inner well unit 32 is positioned to correspond with the second outer well unit 12 to prevent soil from entering the well through the second outer well unit. Before the dewatering / recharge well begins operation, the inner well is rotated to enter the depth of the outer well, so that the first annular inner well unit 31 is positioned to correspond with the second outer well unit 12.

[0072] like Figure 5 As shown, the construction method of the above-mentioned multi-functional dewatering / recharge well includes the following steps:

[0073] S1, Assembly of dewatering / recharge wells.

[0074] S11. Determine the number of the first outer well unit 11 based on the soil hardness.

[0075] The engineering geological conditions in this embodiment are soft soil areas such as Tianjin, so only one first outer well unit is used.

[0076] S12. Based on the depth and thickness of the aquifer intended for precipitation / recharge, determine the number and installation location of the second outer well unit 12, specifically as follows:

[0077] The total length of all second outer well units 12 should not be less than the thickness of the aquifer intended for dewatering / recharge.

[0078] In this embodiment, as Figure 2 As shown, two second outer well units 12 are selected.

[0079] S13. Determine the number and location of the third outer well unit 13 based on the second outer well unit 12, specifically as follows:

[0080] The third outer well unit 13 is located between the bottom end of the second outer well unit 12 (on the side near the anchor head 2) and the first outer well unit 11, as well as between the second outer well unit 12 and the ground surface. The sum of the total lengths of the first outer well unit 11 and the third outer well unit 13 within the range between the second outer well unit 12 and the anchor head 2 is not less than the total length of the second outer well unit 12.

[0081] In this embodiment, as Figure 2 As shown, there is one third outer well unit in the range between the second outer well unit 12 and the anchor head, and four third outer well units in the range between the top of the second outer well unit 12 (away from the anchor head side) and the ground surface.

[0082] S14. Determine the number of the first annular inner well unit 31 based on the number of the second outer well unit 12, and determine the number of the second annular inner well unit 32 based on the number of the second outer well unit 12, the number of the first outer well unit 11, and the number of the third outer well unit 13, specifically as follows:

[0083] The total length of the first annular inner well unit 31 is not less than the total length of the second outer well unit 12, so that all groundwater passing through the second outer well unit can be filtered.

[0084] The total length of the second annular inner well unit 32 is not less than the total length of the second outer well unit 12, so as to ensure that the opening of the second outer well unit can be completely sealed by the second annular inner well unit, preventing soil from being squeezed into the well through the opening of the second outer well unit during subsequent construction.

[0085] The total length of the second annular inner well unit 32 is less than or equal to the sum of the total lengths of all the first outer well units 11 and the third outer well units 13 within the range of the second outer well unit 12 and the anchor head. This ensures that during subsequent use, the second annular inner well unit 32 can move downwards along the outer well until it is completely separated from the corresponding position of the second outer well unit 12.

[0086] S15. Assemble all external well units to form an external well; install the anchor head at the bottom of the external well.

[0087] Each outer well unit is interconnected through the first connecting structure 15 to form the outer well. After the connection is completed, the first spiral pattern 14 on the inner side of each outer well unit can be smoothly connected and transitioned.

[0088] As an example, and not a limitation, the connection between the various external well units is made using anchor bolt connections.

[0089] In this embodiment, as Figure 2 As shown, from top to bottom, four third outer well units 13, two second outer well units 12, one third outer well unit 13, and one first outer well unit 11 are connected in series to form an outer well 1. Then, the anchor head 2 is connected to the first outer well unit 11 at the bottom of the outer well.

[0090] S16. Assemble each annular inner well unit into an inner well, specifically as follows:

[0091] A filter screen 5 is pre-installed in the first annular inner well 31, and filter material 4 is filled in;

[0092] Each annular inner well unit can be interconnected through the second connecting structure 34 to form the annular inner well. After the connection is completed, the second spiral pattern on the outside of each annular inner well unit can be smoothly connected and transitioned.

[0093] In this embodiment, filter media 4 is made of crushed stone and sand.

[0094] In this embodiment, as Figure 2 As shown, from top to bottom, four first annular inner well units 31 and two second annular inner well units 32 are connected in series to form an annular inner well 3.

[0095] S2. The annular inner well 3 is mechanically screwed into the outer well 1 to form a dewatering / recharge well.

[0096] Furthermore, before the completion of the dewatering / recharge well construction, the second annular inner well unit 32 is flush with the second outer well unit 12 near the anchor head. Its function is twofold: firstly, to block the opening of the second outer well unit 12 to prevent soil from being squeezed into the well during the well construction process; and secondly, to increase the rigidity of the second outer well unit 12 to prevent it from being twisted and damaged during the construction process.

[0097] Furthermore, a lifting lug 6 is provided at the top of the annular inner well 3, through which the machinery lifts and rotates the annular inner well.

[0098] S3. Based on project requirements, determine the installation location of the dewatering / recharge wells, and then use machinery to screw the dewatering / recharge wells into the soil to the specified depth. After the dewatering / recharge wells are installed and enter the soil, the second outer well unit 12 of the outer well is basically located within the range of the intended dewatering / recharge aquifer.

[0099] Furthermore, a lifting lug 6 is provided at the top of the outer well 1, allowing the machinery to lift and rotate the outer well. In this embodiment, after the dewatering well is installed into the soil, the second outer well unit 12 of the outer well is entirely located in a confined aquifer.

[0100] S4. After the rainwater / recharge wells have been used, they shall be dismantled and recycled.

[0101] For dewatering wells, the first and second connecting structures at the corresponding depths can be removed as the excavation depth progresses, and the outer well unit and the annular inner well unit can be recovered in sequence.

[0102] For recharge wells, they can be pulled out and recovered by mechanical twisting.

[0103] Furthermore, if recharge is required, a first outer well unit 11 can be installed on the side of the second outer well unit 12 away from the anchor head. The presence of the spiral anchor plate of the first outer well unit can extend the seepage path, thereby inhibiting the overflow of recharge water from the contact surface between the recharge well and the soil to a certain extent.

[0104] The method of using the aforementioned precipitation / recharge wells:

[0105] Before the precipitation / recharge well begins operation, the inner annular well 3 is rotated to enter the depth of the outer well 1, so that the first annular inner well unit 31 of the inner annular well corresponds to the second outer well unit 12 of the outer well.

[0106] During the use of the dewatering / recharge well, depending on the filter media clogging status, the annular inner well 3 is periodically moved closer to the anchor head by mechanically rotating it. This replaces the first annular inner well unit that is in contact with and clogged with the second outer well unit 12 with an unclogged first annular inner well unit. This allows the dewatering / recharge well to operate continuously throughout the process.

[0107] Furthermore, the first annular inner well can be rotatably installed / removed from the outer well, thereby preventing well filter media blockage by periodically replacing / replacing the first annular inner well.

[0108] The methods of using this invention include, but are not limited to, the methods listed above.

[0109] Application comparison:

[0110] like Figure 6 As shown, in this invention, filter media is placed in the first annular well of the annular well. Groundwater from the aquifer first passes through the outer well, then enters the first annular well, is filtered by the filter media in the first annular well, and finally is pumped out of the well. Figure 1 Compared with traditional precipitation wells, the present invention has the following advantages:

[0111] When the filter media becomes clogged, the present invention can pull the first annular inner well containing the clogged filter media out of the outer well, thereby replacing the clogged filter media.

[0112] In terms of well completion quality and construction speed, this invention enables the entire well to be rapidly rotated and implanted into the soil by setting an anchor head at the bottom of the outer well and setting a spiral anchor plate in the first outer well unit.

[0113] From the perspective of well pipe and packing recovery, the outer well of this invention is composed of interconnected outer well units, and the annular inner well is composed of interconnected annular inner well units. Thus, the dewatering well can follow the excavation depth, dismantle the corresponding outer well units and inner well units, and recover the well units.

[0114] The above description is merely a description of preferred embodiments of this application and is not intended to limit the scope of this application in any way. Any changes or modifications made by those skilled in the art based on the above-disclosed technical content should be considered as equivalent and valid embodiments and fall within the scope of protection of the technical solution of this application.

Claims

1. A multifunctional precipitation / recharge well, characterized in that, It includes an outer well, an annular inner well, and an anchor head, wherein the outer well is fitted outside the annular inner well; The outer well is assembled from multiple outer well units, which are of three types: a first outer well unit, a second outer well unit, and a third outer well unit. The first outer well unit has a spiral anchor plate on its outer side for rotating and cutting the soil and driving the well to sink. The second outer well unit has multiple permeable holes on its side for groundwater to seep through. The third outer well unit is a complete well casing. The first outer well unit is located at the bottom of the outer well, the second outer well unit is located at the aquifer location, and the third outer well unit is located above the second outer well unit and between the first and second outer well units. The outer well units are interconnected by a first connecting structure, and after the connection is completed, the first spiral pattern on the inner side of each outer well unit is smoothly connected and transitioned. The annular inner well is assembled from multiple annular inner well units. There are two types of annular inner well units: a first annular inner well unit and a second annular inner well unit. The first annular inner well unit has a hollow internal structure, open at one end and closed at the other. Both the inner and outer rings are provided with water-permeable holes, and a filter screen is laid inside for filling with filter media. The second annular inner well unit has a solid internal structure to increase the overall rigidity of the dewatering / recharge well. The annular inner well units are interconnected by a second connecting structure. After the connection is completed, the second spiral pattern on the outer side of each annular inner well unit is smoothly connected and transitioned. The outer well is provided with a first spiral pattern on its inner side, and the annular inner well is provided with a second spiral pattern on its outer side that matches the first spiral pattern. The annular inner well rotates into or out of the outer well through the first spiral pattern and the second spiral pattern. The total length of all second outer well units shall not be less than the thickness of the aquifer intended for dewatering / recharge; the sum of the total lengths of the second outer well unit and all first and third outer well units within the anchor head range shall not be less than the total length of the second outer well unit; the total length of the first annular inner well unit shall not be less than the total length of the second outer well unit; the total length of the second annular inner well unit shall not be less than the total length of the second outer well unit. The sum of the total lengths of the second outer well unit and all the first and third outer well units within the anchor head range shall not be less than the total length of the second annular inner well unit.

2. The construction method of the multifunctional precipitation / recharge well as described in claim 1, characterized in that, Includes the following steps: Step 1: Assemble the outer well so that the second outer well unit corresponds to the aquifer location. Rotate the outer well to drive it into the ground. The spiral anchor plate at the bottom of the first outer well unit cuts into the soil and guides the outer well to sink until the second outer well unit completely corresponds to the aquifer. Step 2: Assemble the annular inner well, align the second annular inner well unit with the permeable hole position of the second outer well unit, and rotate the annular inner well to screw it into the outer well to prevent soil from rushing in through the permeable hole during the screwing process; Step 3: Before the dewatering / recharge well starts working, the inner annular well is rotated to enter the depth of the outer well, so that the first inner annular well unit corresponds to the second outer well unit, thus completing the installation of the dewatering / recharge well and starting the dewatering or recharge work; The total length of the second outer well unit is not less than the aquifer thickness; the sum of the total lengths of the second outer well unit and the first and third outer well units within the anchor head range is not less than the total length of the second outer well unit; the total length of the first annular inner well unit is not less than the total length of the second outer well unit; the total length of the second annular inner well unit is not less than the total length of the second outer well unit; the sum of the total lengths of the second outer well unit and the first and third outer well units within the anchor head range is not less than the total length of the second annular inner well unit.

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