Construction method of dewatering well in water

Abstract

The invention discloses a construction method of an underwater dewatering well, which comprises 1) a construction method of an underwater double-wall pipe dewatering well and 2) a construction method of an underwater single-wall pipe dewatering well, except that an outer wall pipe needs to be pulled out in the construction, the other steps of the construction of the underwater single-wall pipe dewatering well are the same as the steps of the underwater double-wall pipe dewatering well; the method comprises the following steps: driving an outer water filter pipe or an outer wall pipe below the water bottom mud surface; the inner water filtering pipe is placed in the outer water filtering pipe or the outer wall pipe; the annular cavities are filled with grit, and then the tops of the grit are sealed with clay; and a water pumping pipe with a submersible pump at the lower end is inserted into the lower part of the inner water filtering pipe, and water pumped by the submersible pump is continuously discharged into water outside the cofferdam. Well completion construction of the dewatering well in water can be carried out without providing a land working face, the risk of sudden gushing of the foundation pit is reduced, and the safety of foundation pit construction is greatly improved. And the construction cost is obviously reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of foundation pit dewatering construction, and in particular relates to a method for constructing a dewatering well in water. Background Art

[0002] In the construction and reconstruction of bridges, docks, waterways, ship locks and docks, foundation pit excavation and cofferdam support construction are required, most of which involve foundation pit dewatering construction. According to the amount of precipitation and soil conditions, foundation pit dewatering generally adopts different methods such as light well point dewatering, jet well point dewatering, infiltration well point dewatering and tube well point dewatering. In the actual construction process, light well point dewatering and tube well point dewatering are the most widely used. For foundation pits and cofferdam projects with abundant groundwater, long precipitation time and large precipitation area, the tube well point dewatering process is often used.

[0003] Tube well point dewatering is an effective groundwater control method, which is applicable to various geological conditions such as Quaternary aquifer thickness greater than 5.0m, bedrock fissures and karst aquifers, and aquifer permeability coefficient K greater than 1.0m / d (the height of the formation water level drop every day). The main construction steps include digging mud pools, drilling holes in place with drilling rigs, cleaning holes and replacing slurry, placing well pipes, filling filter materials, washing wells, installing water pumps and laying drainage pipe networks. The operation is cumbersome, with many processes, high well washing costs, low well completion efficiency, long construction period, great difficulty, and the discharge of well washing mud seriously pollutes the environment. Summary of the invention

[0004] The purpose of the present invention is to provide a construction method for a precipitation well in water, which reduces construction steps, shortens construction time, reduces mud pollution, reduces construction costs and improves the well-forming efficiency of the precipitation well.

[0005] The present invention is achieved through the following technical solutions:

[0006] A construction method for an underwater precipitation well, including 1) a construction method for an underwater double-walled pipe precipitation well and 2) a construction method for an underwater single-walled pipe precipitation well;

[0007] The double-walled pipe precipitation well in water includes an inner filter pipe and an outer filter pipe, and the single-walled pipe precipitation well in water includes an inner filter pipe and an outer pipe for temporarily supporting the well wall of the precipitation well;

[0008] 1) The construction method of the double-walled pipe precipitation well in water includes the following steps:

[0009] 1.1) Batch customize the outer water filter pipe and the inner water filter pipe of the required specifications, wherein the lower part of the outer water filter pipe is evenly distributed with a plurality of outwardly convex water-permeable slot holes, and the lower part of the inner water filter pipe is evenly distributed with a plurality of water-permeable circular holes; the bottom of the outer water filter pipe is welded to the top of the pile tip of the outer water filter pipe;

[0010] 1.2) A vibrating hammer is hoisted by a floating crane to vibrate and press down the external water filter pipe, and the external water filter pipe moves downward vertically. The pile tip of the external water filter pipe at the bottom passes through the water body and is driven into the mud surface of the water bottom until the pile tip of the external water filter pipe reaches the designed depth below the mud surface of the water bottom, and the water-permeable slot holes are all located below the mud surface of the water bottom;

[0011] 1.3) Place the lifted inner filter pipe into the outer filter pipe by floating crane until the lower end of the inner filter pipe is positioned on the top of the outer filter pipe pile tip, and center the inner filter pipe so that the thickness of the annular cavity between the outer filter pipe and the inner filter pipe is uniform;

[0012] 1.4) Filling the annular cavity with gravel, and then sealing the top of the gravel with clay until the top surface of the clay is flush with the bottom mud surface;

[0013] 1.5) Insert the suction pipe with a submersible pump at the lower end into the inner filter water pipe until the submersible pump extends into the lower part of the inner filter water pipe, and insert the other end of the suction pipe into the water body outside the cofferdam;

[0014] 1.6) Repeat steps 1.2) to 1.5) for multiple times to complete the construction of each double-walled pipe precipitation well in the water set at intervals; then start each submersible pump to pump water from all the double-walled pipe precipitation wells in the water at the same time until the precipitation of the precipitation project is completed;

[0015] 1.7) After the precipitation project is completed, use the floating crane and vibrating hammer to pull out the inner filter pipe first, and then pull out the outer filter pipe, so as to facilitate the use of the next precipitation project;

[0016] 2) Construction method of single-walled pipe dewatering well in water

[0017] 2.1) Batch customize the outer wall tubes and inner water filter tubes of the required specifications, wherein the lower part of the inner water filter tube is evenly distributed with a plurality of water-permeable circular holes; the bottom of the outer wall tube is connected to the top of the outer wall tube pile tip through a connecting mechanism;

[0018] 2.2) A vibrating hammer is hoisted by a floating crane to vibrate and press down the outer wall pipe. The outer wall pipe moves downward vertically, and the outer wall pipe pile tip at the bottom passes through the water body and is driven into the bottom mud surface until the outer wall pipe pile tip reaches the designed depth below the bottom mud surface;

[0019] 2.3) Place the lifted inner filter pipe into the outer wall pipe by floating crane until the lower end of the inner filter pipe is positioned on the top of the outer wall pipe pile tip, and center the inner filter pipe so that the thickness of the annular cavity between the outer wall pipe and the inner filter pipe is uniform;

[0020] 2.4) Filling the annular cavity with gravel, and then sealing the top of the gravel with clay until the top surface of the clay is flush with the bottom mud surface;

[0021] 2.5) Use a floating crane and a vibrating hammer to pull out the outer wall pipe, and the tip of the outer wall pipe pile remains in the soil at the bottom of the single-wall pipe dewatering well; the pulled-out outer wall pipe will be used for the construction of the next single-wall pipe dewatering well;

[0022] 2.6) Insert the suction pipe with a submersible pump at the lower end into the inner filter pipe until the submersible pump extends into the lower part of the inner filter pipe, and insert the other end of the suction pipe into the water body outside the cofferdam;

[0023] 2.7) Repeat steps 2.2) to 2.6) for multiple times to complete the construction of the single-walled precipitation wells in the water that are set at intervals; then start each submersible pump to pump water from all the single-walled precipitation wells in the water at the same time until the precipitation of the precipitation project is completed;

[0024] 2.8) Use floating crane and vibrating hammer to pull out the inner filter water pipe respectively, so as to facilitate its use in the next precipitation project.

[0025] The purpose of the present invention can be further achieved by the following technical measures.

[0026] Furthermore, the shape of the outer water filter pipe pile tip is the same as that of the outer wall pipe pile tip, both of which are hollow cones with the tip facing downward, including a top plate, a central support tube and a conical outer shell welded together. The specifications of the central support tube are the same as those of the inner water filter pipe. The lower end of the central support tube is welded and fixed on the inner side of the conical outer shell, and the upper end of the central support tube rests on the lower side of the top plate; the bottom of the outer water filter pipe is welded and fixed on the top plate, and the bottom of the outer wall tube is connected to the top of the outer wall pipe pile tip through a connecting mechanism.

[0027] Furthermore, the ratio of the cone height H of the hollow cone to the outer diameter D of the top plate is: H / D=0.85-0.87.

[0028] Furthermore, the connecting mechanism includes several clamping plates evenly distributed on the outer edge of the top plate, and the lower ends of the clamping plates are respectively welded and fixed on the outer edge of the top plate. The difference D1-D2 between the upper outer circle diameter D1 formed by the outer sides of the upper ends of the several clamping plates and the lower outer circle diameter D2 formed by the outer sides of the lower ends of the several clamping plates is 1.5-2.5 mm, and the inner diameter of the outer wall tube is larger than the lower outer circle diameter D2 formed by the outer sides of the lower ends of the several clamping plates.

[0029] Furthermore, the water-permeable slots are like heat dissipation louvers protruding outward, and the sum of the water-permeable slot areas F1 of the outer water filter pipe is ≤ the sum of the water-permeable circular hole areas F2 of the inner water filter pipe.

[0030] Furthermore, the gravel is siliceous gravel, which is obtained by screening through a filter screen with a mesh size of 80 to 100.

[0031] Furthermore, the thickness of the clay is 2.0 to 2.5 m.

[0032] The present invention can carry out well construction of underwater precipitation wells without providing a land working surface, thereby reducing the risk of sudden surges in the foundation pit, greatly improving the safety of foundation pit construction, and making the construction convenient, fast and efficient. The outer filter pipe and the outer wall pipe are made of low-cost steel pipe piles, and the inner filter pipe, the outer filter pipe and the outer wall pipe can all be recycled and reused. In particular, the outer wall pipe can be recycled in the same precipitation project, so only a few outer wall pipes are needed to complete the construction of dozens of precipitation wells, significantly reducing the construction cost. During the construction of the underwater precipitation well, there is no need to configure a mud pool and drilling equipment, so there is no mud pollution, which improves the green and environmental protection level of the construction of the underwater precipitation well.

[0033] Advantages and features of the present invention will be illustrated and explained by the following non-limiting description of preferred embodiments thereof, which are given by way of example only with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a cross-sectional view of the construction of a single-walled pipe dewatering well in water;

[0035] Figure 2 It is a longitudinal section of a double-walled pipe precipitation well in water;

[0036] Figure 3 It is a longitudinal section of a single-walled pipe precipitation well in water after the outer wall pipe has been pulled out;

[0037] Figure 4 This is the main view of the inner filter water pipe;

[0038] Figure 5 This is the main view of the external water filter pipe;

[0039] Figure 6 yes Figure 5 AA section enlarged view;

[0040] Figure 7 yes Figure 3 Enlarged view of part I. DETAILED DESCRIPTION

[0041] The present invention will be further described below in conjunction with the accompanying drawings and an embodiment of the Nantong Xiangyu Shipyard slipway reconstruction project. Figure 1 As shown, the renovation area has been enclosed by a steel sheet pile cofferdam 200 to form a closed rectangular construction area. Six underwater single-walled pipe drainage wells 20 are arranged at intervals on both sides of the longitudinal cofferdam in the rectangular construction area, and one single-walled pipe drainage well 20 is arranged in the transverse cofferdam close to the shore, for a total of 13 single-walled pipe drainage wells 20.

[0042] like Figure 1 to Figure 7 As shown, the present invention includes 1) a construction method of a double-walled pipe dewatering well 10 in water and 2) a construction method of a single-walled pipe dewatering well 20 in water;

[0043] The double-walled pipe precipitation well 10 in water includes an inner filter pipe 11 and an outer filter pipe 12, and the single-walled pipe precipitation well 20 in water includes an inner filter pipe 11 and an outer wall pipe 21 for temporarily supporting the well wall of the precipitation well. In this embodiment, the outer diameters of the outer filter pipe 12 and the outer wall pipe 21 are both Φ650mm. During the construction process, the outer filter pipe 12 and the outer wall pipe 21 need to be compressed, and the wall thickness is 10mm to prevent squeezing and deformation when pressed down. The outer diameter of the inner filter pipe 11 is Φ273mm and the wall thickness is 3mm.

[0044] Embodiment 1:

[0045] 1) The construction method of the underwater double-walled pipe precipitation well 10 comprises the following steps:

[0046] 1.1) Batch customize the outer filter pipe 11 and the inner filter pipe 12 of the required specifications, such as Figure 5 and Figure 6 As shown, a plurality of outwardly convex water-permeable slots 111 are evenly distributed at the lower part of the outer water filter pipe 11. Figure 4 As shown, the lower part of the inner water filter pipe is evenly distributed with a plurality of water-permeable circular holes 121. The bottom of the outer water filter pipe 11 is welded to the top of the outer water filter pipe pile tip 13.

[0047] 1.2) If Figure 1 As shown, a floating crane 100 is used to lift a vibrating hammer 101 to vibrate and press down the external water filter pipe 11. The external water filter pipe 11 descends vertically, and the external water filter pipe pile tip 13 at its bottom passes through the water body and is driven into the water bottom mud surface 300 until the external water filter pipe pile tip 13 reaches the designed depth below the water bottom mud surface 300, and the permeable trough holes 111 are all located below the water bottom mud surface 300.

[0048] 1.3) Place the lifted inner water filter pipe 12 into the outer water filter pipe 11 by means of the floating crane 100 until the lower end of the inner water filter pipe 12 is positioned on the top of the outer water filter pipe pile tip 13, and center the inner water filter pipe 12 so that the thickness of the annular cavity 3 between the outer water filter pipe 11 and the inner water filter pipe 12 is uniform.

[0049] 1.4) Gravel 4 is filled in the annular cavity 3, and then the top of the gravel 4 is sealed with clay 5 until the top surface of the clay 5 is flush with the bottom mud surface 300, and the thickness of the clay 5 is 2.0 to 2.5 m.

[0050] 1.5) Insert the suction pipe 6 with a submersible pump 61 at the lower end into the inner water filter pipe 12 until the submersible pump 61 extends into the lower part of the inner water filter pipe 12, and insert the other end of the suction pipe 6 into the water body outside the cofferdam 200.

[0051] 1.6) Repeat steps 1.2) to 1.5) for multiple times to complete the construction of the interval-set double-walled pipe dewatering wells 10. Then start each submersible pump 61 to pump water from the corresponding double-walled pipe dewatering wells 10 in the water at the same time until the dewatering project is completed.

[0052] 1.7) After the precipitation project is completed, the vibrating hammer 101 is lifted by the floating crane 100 to first pull out the inner filter pipe 12 and then the outer filter pipe 11, so as to facilitate the use in the next precipitation project.

[0053] Embodiment 2:

[0054] 2) Construction method of underwater single-wall pipe dewatering well 20

[0055] 2.1) Batch customize the outer wall tube 21 and inner filter water tube 12 of required specifications, Figure 4 The lower part of the inner filter pipe 12 is evenly distributed with a plurality of water-permeable circular holes 121. The bottom of the outer wall pipe 21 is connected to the top of the outer wall pipe pile tip 23 through a connecting mechanism 22.

[0056] 2.2) The vibrating hammer 101 is lifted by the floating crane 100 to vibrate and press down the outer wall pipe 21, and the outer wall pipe 21 moves downward vertically, and the outer wall pipe pile tip 23 at the bottom passes through the water body and is driven into the bottom mud surface 300 until the outer wall pipe pile tip 23 reaches the designed depth below the bottom mud surface 300.

[0057] 2.3) Place the lifted inner water filter pipe 12 into the outer wall pipe 21 by means of the floating crane 100 until the lower end of the inner water filter pipe 12 is positioned on the top of the outer wall pipe pile tip 23, and center the inner water filter pipe 12 so that the thickness of the annular cavity 4 between the outer wall pipe 21 and the inner water filter pipe 12 is uniform.

[0058] 2.4) Gravel 4 is filled in the annular cavity 3, and then the top of the gravel 4 is sealed with clay 5 until the top surface of the clay 4 is flush with the bottom mud surface 300, and the thickness of the clay 5 is 2.0-2.5m.

[0059] 2.5) Use the floating crane 100 and the vibrating hammer 101 to pull out the outer wall pipe 21 , and the outer wall pipe pile tip 23 remains in the soil at the bottom of the single-wall pipe dewatering well 20 ; the pulled out outer wall pipe 21 will be used for the construction of the next single-wall pipe dewatering well 20 .

[0060] 2.6) Insert the suction pipe 6 with a submersible pump 61 at the lower end into the inner water filter pipe 12 until the submersible pump 61 extends into the lower part of the inner water filter pipe 12, and the other end of the suction pipe 6 is inserted into the water body outside the cofferdam.

[0061] 2.7) Repeat steps 2.2) to 2.6) for multiple times to complete the construction of the single-walled pipe dewatering wells 20 arranged at intervals. Then start each submersible pump 61 to pump water from all the single-walled pipe dewatering wells 20 in the water at the same time until the dewatering of the dewatering project is completed;

[0062] Then start all the water pumps at the same time to pump water until the precipitation project is completed.

[0063] 2.8) Use a floating crane to lift a vibrating hammer and pull out the inner filter pipes 12 respectively, so as to facilitate use in the next precipitation project.

[0064] like Figure 7 As shown, the shape of the outer water filter pipe pile tip 13 is the same as that of the outer wall pipe pile tip 23, both of which are hollow cones with the cone tip facing downward, including a top plate 131, a central support pipe 132 and a conical shell 133 welded together. The specifications of the central support pipe 132 are the same as those of the inner water filter pipe 12. The lower end of the central support pipe 132 is welded and fixed on the inner side of the conical shell 133, and the upper end of the central support pipe 132 abuts against the lower side of the top plate 131. The bottom of the inner water filter pipe 12 is welded and fixed on the top plate 131, and the bottom of the outer wall pipe 21 is connected to the top of the outer wall pipe pile tip 23 through a connecting mechanism 22. The ratio of the cone height H of the hollow cone to the outer diameter D of the top plate is: H / D=0.86. The lower cone height H and the structure of the built-in central support tube 132 improve the strength and rigidity of the outer water filter pipe pile tip 13 and the outer wall pipe pile tip 23, making the outer water filter pipe pile tip 13 and the outer wall pipe pile tip 23 stronger and more durable.

[0065] like Figure 3 and Figure 7 As shown, the connecting mechanism 22 includes four clamping plates 221 evenly distributed on the outer edge of the top plate 131, and the lower ends of the clamping plates 221 are respectively welded and fixed on the outer edge of the top plate 131. The difference D1-D2 between the upper outer diameter D1 formed by the outer sides of the upper ends of the four clamping plates 221 and the lower outer diameter D2 formed by the outer sides of the lower ends of several clamping plates is 1.5-2.5 mm. The inner diameter of the outer wall tube is greater than the lower outer diameter D2 formed by the outer sides of the lower ends of the four clamping plates 221, indicating that the clamping plates 221 are slightly inclined outward. When the four clamping plates 221 at the upper end of the outer wall tube pile tip 23 are inserted into the inner hole at the lower end of the outer wall tube 21, the outer side surfaces of the four clamping plates 221 can be tightly pressed against the inner hole at the lower end of the outer wall tube 21, thereby realizing a reliable connection between the outer wall tube pile tip 23 and the outer wall tube 21. When the floating crane 100 is used to pull out the outer wall pipe 21, the lifting force is much greater than the static friction between the four clamping plates 221 at the upper end of the outer wall pipe pile tip 23 and the inner hole of the outer wall pipe 21, so the outer wall pipe 21 is separated from the outer wall pipe pile tip 23, and the outer wall pipe pile tip 23 remains at the bottom of the single-wall pipe dewatering well 20 in the water.

[0066] like Figure 6 As shown, the water-permeable slots 111 are like heat dissipation shutters protruding outwards. The structure that the water-permeable slots 111 are not directly facing outwards can effectively prevent mud from clogging the water-permeable slots 111, thereby improving the reliability of the outer filter pipe 11. The sum of the water-permeable slot hole areas F1 is ≤ the sum of the water-permeable circular hole areas F2 of the inner filter pipe 12, thereby preventing the water in the inner filter pipe 12 from flowing back into the outer filter pipe 11, thereby affecting the precipitation effect.

[0067] Gravel 4 is siliceous gravel, which is obtained by screening through a filter screen with a mesh size of 80 to 100.

[0068] In addition to the above embodiments, the present invention may also have other implementation modes. All technical solutions formed by equivalent replacement and equivalent transformation fall within the protection scope required by the present invention.

Claims

1. A method for constructing a precipitation well in water, characterized in that: Including 1) a construction method of a double-walled pipe dewatering well in water and 2) a construction method of a single-walled pipe dewatering well in water; The double-walled pipe precipitation well in water includes an inner filter pipe and an outer filter pipe, and the single-walled pipe precipitation well in water includes an inner filter pipe and an outer pipe for temporarily supporting the well wall of the precipitation well; 1) The construction method of the double-walled pipe precipitation well in water includes the following steps: 1.1) Batch customize the outer water filter pipe and the inner water filter pipe of the required specifications, wherein the lower part of the outer water filter pipe is evenly distributed with a plurality of outwardly convex water-permeable slot holes, and the lower part of the inner water filter pipe is evenly distributed with a plurality of water-permeable circular holes; the bottom of the outer water filter pipe is welded to the top of the pile tip of the outer water filter pipe; 1.2) A vibrating hammer is hoisted by a floating crane to vibrate and press down the external water filter pipe, and the external water filter pipe moves downward vertically. The pile tip of the external water filter pipe at the bottom passes through the water body and is driven into the mud surface of the water bottom until the pile tip of the external water filter pipe reaches the designed depth below the mud surface of the water bottom, and the water-permeable slot holes are all located below the mud surface of the water bottom; 1.3) Place the lifted inner filter pipe into the outer filter pipe by floating crane until the lower end of the inner filter pipe is positioned on the top of the outer filter pipe pile tip, and center the inner filter pipe so that the thickness of the annular cavity between the outer filter pipe and the inner filter pipe is uniform; 1.4) Filling the annular cavity with gravel, and then sealing the top of the gravel with clay until the top surface of the clay is flush with the bottom mud surface; 1.5) Insert the suction pipe with a submersible pump at the lower end into the inner filter water pipe until the submersible pump extends into the lower part of the inner filter water pipe, and insert the other end of the suction pipe into the water body outside the cofferdam; 1.6) Repeat the process of steps 1.2) to 1.5) for many times to complete the construction of each double-walled pipe precipitation well in the water set at intervals; then start each submersible pump to pump water from all the double-walled pipe precipitation wells in the water at the same time until the precipitation of the precipitation project is completed; 1.7) After the precipitation project is completed, use the vibrating hammer lifted by the floating crane to pull out the inner filter pipe first, and then pull out the outer filter pipe, so as to facilitate the use of the next precipitation project; 2) Construction method of single-wall pipe dewatering well in water 2.1) Batch customize the outer wall tube and inner water filter tube of the required specifications, wherein the lower part of the inner water filter tube is evenly distributed with a plurality of water-permeable circular holes; the bottom of the outer wall tube is connected to the top of the outer wall tube pile tip through a connecting mechanism; 2.2) A vibrating hammer is hoisted by a floating crane to vibrate and press down the outer wall pipe. The outer wall pipe moves downward vertically, and the outer wall pipe pile tip at the bottom passes through the water body and is driven into the bottom mud surface until the outer wall pipe pile tip reaches the designed depth below the bottom mud surface; 2.3) Place the lifted inner filter pipe into the outer wall pipe by floating crane until the lower end of the inner filter pipe is positioned on the top of the outer wall pipe pile tip, and center the inner filter pipe so that the thickness of the annular cavity between the outer wall pipe and the inner filter pipe is uniform; 2.4) Filling the annular cavity with gravel, and then sealing the top of the gravel with clay until the top surface of the clay is flush with the bottom mud surface; 2.5) Use an excavator and an electric hammer to pull out the outer wall pipe, and the tip of the outer wall pipe pile remains in the soil at the bottom of the single-wall pipe dewatering well; the pulled-out outer wall pipe will be used for the construction of the next single-wall pipe dewatering well; 2.6) Insert the suction pipe with a submersible pump at the lower end into the inner filter pipe until the submersible pump extends into the lower part of the inner filter pipe, and insert the other end of the suction pipe into the water body outside the cofferdam; 2.7) Repeat steps 2.2) to 2.6) for multiple times to complete the construction of the single-walled precipitation wells in the water that are set at intervals; then start each submersible pump to pump water from all the single-walled precipitation wells in the water at the same time until the precipitation of the precipitation project is completed; 2.8) Use an excavator and an electric hammer to pull out the inner filter pipe for use in the next precipitation project.

2. The construction and dewatering method of a water dewatering well as claimed in claim 1, characterized in that: The shape of the outer water filter pipe pile tip is the same as that of the outer wall pipe pile tip, both of which are hollow cones with the tip facing downward, including a top plate, a central support pipe and a conical outer shell welded together. The specifications of the central support pipe are the same as those of the inner water filter pipe. The lower end of the central support pipe is welded and fixed on the inner side of the conical outer shell, and the upper end of the central support pipe rests on the lower side of the top plate; the bottom of the inner water filter pipe is welded and fixed on the top plate, and the bottom of the outer wall pipe is connected to the top of the outer wall pipe pile tip through a connecting mechanism.

3. The construction and dewatering method of a water dewatering well as claimed in claim 2, characterized in that: The ratio of the cone height H of the hollow cone to the outer diameter D of the top plate is: H / D=0.85~0.

87.

4. The construction and dewatering method of a water dewatering well as claimed in claim 2, characterized in that: The connecting mechanism includes several clamping plates evenly distributed on the outer edge of the top plate, and the lower ends of the clamping plates are respectively welded and fixed on the outer edge of the top plate. The difference D1-D2 between the upper outer circle diameter D1 surrounded by the outer sides of the upper ends of the several clamping plates and the lower outer circle diameter D2 surrounded by the outer sides of the lower ends of the several clamping plates is 1.5-2.5 mm, and the inner diameter of the outer wall tube is larger than the lower outer circle diameter D2 surrounded by the outer sides of the lower ends of the several clamping plates.

5. The construction and dewatering method of a water dewatering well as claimed in claim 1, characterized in that: The water-permeable slots are like heat dissipation louvers protruding outward, and the sum of the water-permeable slot areas F1 of the outer water filter pipe is ≤ the sum of the water-permeable circular hole areas F2 of the inner water filter pipe.

6. The construction and dewatering method of a water dewatering well as claimed in claim 1, characterized in that: The sand and gravel are siliceous sand and gravel, which are obtained by screening through a filter screen with 80-100 meshes.

7. The construction and dewatering method of a water dewatering well as claimed in claim 1, characterized in that: The thickness of the clay is 2.0-2.5 m.

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