A kind of civil construction foundation pit drainage structure and construction method thereof

Abstract

The present invention discloses a drainage structure for a foundation pit for civil engineering construction, including a drainage cylinder installed in the foundation pit, the drainage cylinder including a mounting plate, an outer cylinder, an inner cylinder and a partition bottom plate, a filter chamber is formed between the outer cylinder and the inner cylinder, the lower end surfaces of the inner cylinder and the outer cylinder are respectively provided with a first filter hole and a second filter hole, a pump column is slidably inserted in the inner cylinder, a tunneling drill is rotatably installed at the bottom of the drainage cylinder, and a driving assembly is also provided on the drainage cylinder, and the tunneling drill is controlled by the driving assembly. The drainage structure proposed by the present invention, as the foundation pit is excavated in layers, the drainage cylinder is pushed downward layer by layer, the precipitation depth is controlled to be 0.5-1 meters below the excavation layer, the slope of the precipitation funnel line is slowed down, the disturbance to the groundwater of the next excavation layer is reduced, the influence of the horizontal radial flow of groundwater is reduced, the precipitation volume is reduced, and it is ensured that the excavation layer can be quickly precipitated and drained, which provides convenience for the execution and monitoring of precipitation on demand.

Description

Technical Field

[0001] The invention relates to the technical field of foundation pit drainage, and in particular to a civil construction foundation pit drainage structure and a construction method thereof. Background Art

[0002] During foundation pit construction, in order to increase the stability of the slope and the bottom of the pit, reduce the moisture content of the excavated soil, facilitate excavation, or prevent sudden surges, it is necessary to dewater the foundation pit. It is divided into drainage dewatering and pressure reduction dewatering. Commonly used dewatering methods include open drainage, light well points, jet well points, tube wells, etc.

[0003] In the prior art, for example, the patent application number is 202111646876.X, which discloses a drainage structure for a foundation pit for civil engineering construction, which includes a foundation pit body and a water storage tank buried at the bottom of the foundation pit body, the water storage tank is provided with a water inlet, the bottom of the foundation pit body is provided with a water guide groove, the water guide groove is connected to the water inlet of the water storage tank, the water storage tank is connected with a drainage pipe, the end of the drainage pipe away from the water storage tank is connected with the water storage tank, the water storage tank is arranged on the top of the foundation pit body, the drainage pipe is provided with a pump for pumping water in the water storage tank to the water storage tank; the water storage tank is connected with a water guide pipe, the water guide pipe is buried in the periphery of the foundation pit body, and the water guide pipe is connected with a plurality of water outlet pipes. The present application has the effect of high stability of the overall structure of the foundation pit when the foundation pit is drained.

[0004] In short, the above scheme uses the method of recharging to improve the stability of the foundation pit slope, but its disadvantage is that it is not conducive to the implementation of "precipitation on demand", that is, the precipitation level is determined according to the layered excavation depth, and excessive lowering of the groundwater level in the foundation pit should be avoided, otherwise it will cause a large amount of recharged water from the periphery of the foundation pit to seep back into the pit (reference Figure 6 ), ineffective circulation drainage not only increases drainage costs, but also causes fine soil loss and slope instability. Summary of the invention

[0005] The purpose of the present invention is to solve the shortcomings of the prior art and to propose a civil construction foundation pit drainage structure and a construction method thereof.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A drainage structure for a foundation pit of a civil engineering construction project comprises a drainage cylinder installed in the foundation pit, wherein the drainage cylinder comprises a mounting plate, an outer cylinder, an inner cylinder and a partition bottom plate, wherein the outer cylinder is fixedly mounted on the lower side of the mounting plate, the inner cylinder is arranged in the outer cylinder, the inner cylinder is fixedly connected to the mounting plate, and the partition bottom plate is fixedly mounted between the outer cylinder and the inner cylinder, a filter chamber is formed between the outer cylinder and the inner cylinder, and a first filter hole and a second filter hole are respectively provided on the lower end surfaces of the inner cylinder and the outer cylinder.

[0008] The first intercepting sleeve and the second intercepting sleeve are rotatably installed in the filter chamber respectively, and the surfaces of the first intercepting sleeve and the second intercepting sleeve are both provided with flow guide openings. The first intercepting sleeve controls the opening and closing of the first filter hole, and the second intercepting sleeve controls the opening and closing of the second filter hole.

[0009] A pump column is slidably inserted in the inner cylinder, a flow channel hole penetrating up and down is opened inside the pump column, and a drainage pipe connected with the flow channel hole is installed at the top of the pump column.

[0010] A tunneling drill is rotatably mounted on the bottom end of the drainage cylinder, and a driving assembly is also provided on the drainage cylinder, through which the actions of the first intercepting sleeve, the second intercepting sleeve and the tunneling drill are controlled.

[0011] Preferably, an exhaust duct is installed on the upper surface of the mounting plate, the lower end of the exhaust duct extends into the filter chamber, the exhaust duct is externally connected to an air pump, and the filter chamber is filled with filter sand and gravel.

[0012] Preferably, an exhaust duct is installed on the upper surface of the mounting plate, the lower end of the exhaust duct extends into the filter chamber, the exhaust duct is externally connected to a one-way exhaust valve, and the filter chamber is filled with filter sand and gravel.

[0013] Preferably, the tunneling drill is rotatably mounted at the lower end of the inner cylinder, and the tunneling drill is hidden in the lower opening of the outer cylinder. The tunneling drill includes spiral blades, an outer cover and a guide dividing ring. The guide dividing ring divides the outer cover into two upper and lower chambers. The spiral blades are fixedly arranged in the lower chamber of the outer cover. The central hole of the guide dividing ring connects the lower chamber of the outer cover with the inner cylinder. The inner wall of the upper chamber of the outer cover is fixedly provided with a first gear ring.

[0014] Preferably, a second toothed ring is fixedly mounted on the surface of the first intercepting sleeve, and a third toothed ring is fixedly mounted on the inner wall of the second intercepting sleeve.

[0015] Preferably, the drive assembly includes a transmission shaft, gears, a hydraulic motor, a hydraulic cylinder and a shaft sleeve. The transmission shaft is rotatably mounted on a mounting plate. The transmission shaft passes downward through the filter chamber and extends to the lower side of the partition bottom plate. Two gears are fixedly mounted on the surface of the transmission shaft. The shaft sleeve is fixedly connected to the upper end of the transmission shaft. The rotating shaft of the hydraulic motor is slidably inserted into the shaft sleeve. A lifting sleeve is fixedly mounted on the telescopic end of the hydraulic cylinder. The shaft sleeve is rotatably arranged in the lifting sleeve. The transmission shaft is controlled to reciprocate up and down by the hydraulic cylinder, so that one gear is meshed with the first gear ring for transmission, or another gear is meshed with the second gear ring or the third gear ring for transmission.

[0016] The present invention has the following beneficial effects:

[0017] 1. The drainage structure proposed in the present invention, with the layered excavation of the foundation pit, the drainage tube is pushed downward layer by layer, and the precipitation depth is controlled to 0.5-1 meter below the excavation layer, slowing down the slope of the precipitation funnel line, reducing the disturbance to the groundwater of the next excavation layer, reducing the impact of the horizontal radial flow of groundwater, reducing the precipitation volume, ensuring that the excavation layer can be quickly precipitated and drained, and providing convenience for the execution and monitoring of precipitation on demand.

[0018] 2. This drainage structure, by setting a pump column in the drainage cylinder, uses the up and down reciprocating movement of the pump column to pressurize the groundwater to the ground. Compared with the prior art method of setting a water pump to pump water continuously, it can effectively avoid a series of problems of the water pump running dry, especially when the underground soil layer has poor permeability and the seepage speed of the precipitation well cannot keep up with the pumping speed.

[0019] 3. By filling the filter chamber in the drainage tube with filter sand and gravel to filter the underground flowing soil and maintain smooth permeability, and using the exhaust duct to suck air, a negative pressure is generated in the drainage tube, which is conducive to the rapid infiltration of groundwater. The drainage tube only dewaters the excavated layer to achieve drainage, effectively reducing the water content of the excavated soil, thereby improving the stability of the slope, increasing the consolidation strength of the soil in the pit, facilitating mechanical excavation, and providing conditions for dry operation in the pit.

[0020] 4. The drainage structure is equipped with a tunneling drill, which saves a lot of time for digging wells and dewatering before foundation pit construction. As the excavation proceeds downward by itself, especially for dewatering in the foundation pit, there is a problem of frequent transfer of dewatering equipment on the excavation surface. The overall structure of the drainage structure is compact, lightweight, and reusable. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the overall three-dimensional structure of the drainage structure proposed by the present invention;

[0022] Figure 2 This is a schematic diagram of the front cross-section structure of the drainage tube proposed by the present invention;

[0023] Figure 3 A schematic diagram of the three-dimensional structure of the tunneling drill proposed by the present invention;

[0024] Figure 4 This is a schematic diagram of the front cross-section structure of the drainage structure proposed by the present invention;

[0025] Figure 5 A schematic diagram of single well point dewatering proposed by the present invention;

[0026] Figure 6 This is a schematic diagram of the foundation pit groundwater proposed by the present invention.

[0027] In the figure: 1 mounting plate, 2 outer cylinder, 3 inner cylinder, 4 partition bottom plate, 5 filter chamber, 6 first filter hole, 7 second filter hole, 8 first intercepting sleeve, 9 second intercepting sleeve, 10 pump column, 11 flow channel hole, 12 drainage pipe, 13 excavation drill, 14 exhaust duct, 15 spiral blade, 16 outer cover, 17 guide and separation ring, 18 transmission shaft, 19 hydraulic motor, 20 hydraulic cylinder, 21 shaft sleeve, 22 lifting sleeve. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0029] In the description of the present invention, it is necessary to understand that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0030] Reference Figure 1-6 , a civil construction foundation pit drainage structure, including a drainage cylinder installed in the foundation pit, see Figure 2 The drainage cylinder includes a mounting plate 1, an outer cylinder 2, an inner cylinder 3 and a partition bottom plate 4. The outer cylinder 2 is fixedly mounted on the lower side of the mounting plate 1, the inner cylinder 3 is arranged in the outer cylinder 2, the inner cylinder 3 is fixedly connected to the mounting plate 1, and the partition bottom plate 4 is fixedly mounted between the outer cylinder 2 and the inner cylinder 3. A filter chamber 5 is formed between the outer cylinder 2 and the inner cylinder 3. The lower end surfaces of the inner cylinder 3 and the outer cylinder 2 are respectively provided with a first filter hole 6 and a second filter hole 7.

[0031] Reference Figure 1 A first intercepting sleeve 8 and a second intercepting sleeve 9 are rotatably installed in the filter chamber 5, and the surfaces of the first intercepting sleeve 8 and the second intercepting sleeve 9 are both provided with flow guide openings. The first intercepting sleeve 8 controls the opening and closing of the first filter hole 6, and the second intercepting sleeve 9 controls the opening and closing of the second filter hole 7.

[0032] A pump column 10 is slidably inserted into the inner cylinder 3 , a flow channel hole 11 penetrating from top to bottom is opened inside the pump column 10 , and a drainage pipe 12 communicating with the flow channel hole 11 is installed at the top end of the pump column 10 .

[0033] A tunneling drill 13 is rotatably mounted at the bottom end of the drainage tube, and a driving assembly is also provided on the drainage tube, through which the first intercepting sleeve 8, the second intercepting sleeve 9 and the tunneling drill 13 are controlled to move.

[0034] Specifically, the driving assembly includes a transmission shaft 18, gears, a hydraulic motor 19, a hydraulic cylinder 20 and a shaft sleeve 21. The transmission shaft 18 is rotatably mounted on the mounting plate 1. The transmission shaft 18 passes downward through the filter chamber 5 and extends to the lower side of the partition bottom plate 4. Two gears are fixedly mounted on the surface of the transmission shaft 18. The shaft sleeve 21 is fixedly connected to the upper end of the transmission shaft 18. The rotating shaft of the hydraulic motor 19 is slidably inserted into the shaft sleeve 21. The telescopic end of the hydraulic cylinder 20 is fixedly mounted with a lifting sleeve 22, and the shaft sleeve 21 is rotatably arranged in the lifting sleeve 22.

[0035] The tunneling drill 13 is rotatably installed at the lower end of the inner cylinder 3, and the tunneling drill 13 is hidden in the lower mouth of the outer cylinder 2. The tunneling drill 13 includes a spiral blade 15, an outer cover 16 and a guide dividing ring 17. The guide dividing ring 17 divides the outer cover 16 into two upper and lower chambers. The spiral blade 15 is fixedly arranged in the lower chamber of the outer cover 16. The central hole of the guide dividing ring 17 connects the lower chamber of the outer cover 16 with the inner cylinder 3. The inner wall of the upper chamber of the outer cover 16 is fixedly provided with a first gear ring.

[0036] A second gear ring is fixedly mounted on the surface of the first intercepting sleeve 8, and a third gear ring is fixedly mounted on the inner wall of the second intercepting sleeve 9. The transmission shaft 18 is reciprocated up and down by controlling the hydraulic cylinder 20 to mesh with the first gear ring for transmission, or to mesh with the second gear ring and the third gear ring for transmission.

[0037] When the hydraulic cylinder 20 pushes down the transmission shaft 18, the gear on the lower side meshes with the first gear ring for transmission, and the hydraulic motor 19 drives the excavation drill 13 to rotate, so that the drainage structure has the function of drilling holes and sinking, which saves a lot of time for well drilling and dewatering before foundation pit construction. As the foundation pit is excavated, the drainage tube is excavated downward by itself, especially for dewatering in the foundation pit. There is a problem of frequent transfer of dewatering equipment on the excavation surface. The overall structure of the drainage structure is compact, lightweight, and reusable.

[0038] When the hydraulic cylinder 20 lifts the transmission shaft 18, the upper gear meshes with the second gear ring and the third gear ring, and the first intercepting sleeve 8 and the second intercepting sleeve 9 block the first filter hole 6 and the second filter hole 7 in turn. At this time, the water seepage holes around the drainage cylinder are closed, and the pump column 10 moves down in the inner cylinder 3. When the pump column 10 presses down the seepage water in the drainage cylinder, the water is pressed from the flow channel hole 11 to the drainage pipe 12. Figure 5 shown.

[0039] By setting a pump column 10 in the drainage barrel and utilizing the up and down reciprocating movement of the pump column 10 to pressurize the groundwater to the ground, compared with the prior art method of setting a water pump to pump water continuously, a series of problems of the water pump running dry can be effectively avoided, especially when the underground soil layer has poor permeability and the seepage speed of the precipitation well cannot keep up with the pumping speed.

[0040] In this embodiment, an exhaust duct 14 is installed on the upper surface of the mounting plate 1, and the lower end of the exhaust duct 14 extends into the filter chamber 5, which is filled with filter sand and gravel. The exhaust duct 14 can be externally connected to an air pump or an external one-way exhaust valve.

[0041] like Figure 5 When the vacuum pump is used, the air in the filter chamber 5 is sucked through the exhaust duct 14, so that negative pressure is generated in the drainage tube, which is conducive to the rapid infiltration of groundwater. Moreover, the drainage tube only dewaters the excavated layer to achieve drainage, effectively reducing the water content of the excavated soil, thereby improving the stability of the slope, increasing the consolidation strength of the soil in the pit, facilitating mechanical excavation, and providing conditions for dry operation in the pit.

[0042] Similarly, when using a one-way exhaust valve, the up and down reciprocating movement of the pump column 10 is utilized to pressurize the groundwater to the ground while exhausting the air in the filter chamber 5 through the exhaust duct 14. When the pump column 10 is lifted again, the one-way exhaust valve blocks the air intake of the exhaust duct 14, so that a negative pressure is formed in the filter chamber 5, which is equivalent to using an air pump, thereby accelerating the infiltration of groundwater. This is suitable for slow water seepage in foundation pits, and the up and down movement of the pump column 10 can be used to simultaneously achieve filtered drainage and negative pressure drainage.

[0043] It should be noted that, especially when the underground soil permeability is poor and the water seepage rate of the precipitation well cannot keep up with the pumping rate, for example, when multiple well points are dewatered at the same time and connected to the pump room by series pipes, if one well point has no water, the series pipes will draw air and other well points will not be able to pump water normally. Correspondingly, it is necessary to increase manual real-time monitoring to record the water level and the operation of the water pump. The labor burden and costs will increase accordingly, which is not conducive to management. If there is water intermittently and the water pump continues to run, the water hammer caused by the sudden water flow will damage the water pump and the equipment cost will also increase. The drainage structure proposed in the present invention arranges a pump column 10 in the drainage barrel and uses the up and down reciprocating movement of the pump column 10 to press the groundwater to the ground. Compared with the prior art method of setting a water pump to pump water continuously, it can effectively avoid a series of problems of the water pump running dry.

[0044] In this embodiment, a construction method for drainage of foundation pit for civil construction is also proposed, comprising the following specific steps:

[0045] S1. Installation of drainage cylinders: Before excavation of the foundation pit, reasonably distribute the precipitation points, hoist the drainage cylinders at the precipitation points, and place the drainage cylinders on the ground;

[0046] S2, the excavation of the drainage barrel, the transmission shaft 18 is driven by the hydraulic motor 19, and the excavation drill 13 is driven to rotate, and water is poured into the inner barrel 3 at the same time. The drill rotates to dig and stir the soil, and the mud is pumped out by the pump, and the drainage barrel gradually sinks and inserts into the ground;

[0047] S3, filter drainage, slide the pump column 10 into the inner cylinder 3, use the hoist to lift and lower the pump column 10, the pump column 10 moves up and down, when the pump column 10 moves up, there is a large space in the inner cylinder 3, the groundwater is filtered by the sand and gravel, and penetrates into the inner cylinder 3, filtering out the underground flow soil, maintaining smooth permeability, when the pump column 10 presses down the seepage water in the drainage cylinder, the water is pressed from the flow channel hole 11 to the drainage pipe 12, and then discharged by the water collection open drainage method;

[0048] S4, negative pressure drainage, in the process of drainage in step S3, negative pressure is pumped into the filter chamber 5 to accelerate the seepage of groundwater into the drainage cylinder, so as to drain the soil in the foundation excavation area;

[0049] S5, the process of layered excavation of the foundation pit, repeating step S2, with the decrease of the elevation of the bottom surface of the foundation pit excavation, the drainage cylinder is lowered layer by layer.

[0050] It should be noted that the existing technology uses the method of recharging to improve the stability of the foundation pit slope and compensate for the instability of the foundation pit caused by precipitation. The actual precipitation should avoid excessively lowering the groundwater level, otherwise it will cause a large amount of recharged water from the periphery of the foundation pit to seep back into the pit. Figure 6 When the water level line moves down during precipitation, the pressure water level line will also move down. The groundwater outside the foundation pit will seep back into the foundation pit, requiring a lot of ineffective circulating drainage work.

[0051] The drainage structure proposed by the present invention, as the foundation pit is excavated layer by layer, the drainage tube is pushed downward layer by layer. Figure 5 , control the groundwater level after precipitation to 0.5-1 meter below the first excavation depth, slow down the slope of the precipitation funnel line (i.e. the slope of the water level after precipitation), reduce the disturbance to the groundwater in the next excavation layer, reduce the impact of horizontal radial flow of groundwater, reduce the precipitation volume, ensure that the excavation layer can be quickly precipitated and drained, and provide convenience for the implementation and monitoring of precipitation on demand.

[0052] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A drainage structure for a foundation pit for civil construction, comprising a drainage cylinder installed in the foundation pit, characterized in that: The drainage cylinder comprises a mounting plate (1), an outer cylinder (2), an inner cylinder (3) and a partition bottom plate (4); the outer cylinder (2) is fixedly mounted on the lower side of the mounting plate (1); the inner cylinder (3) is arranged inside the outer cylinder (2); the inner cylinder (3) is fixedly connected to the mounting plate (1); and the partition bottom plate (4) is fixedly mounted between the outer cylinder (2) and the inner cylinder (3); a filter chamber (5) is formed between the outer cylinder (2) and the inner cylinder (3); and the lower end surfaces of the inner cylinder (3) and the outer cylinder (2) are respectively provided with a first filter hole (6) and a second filter hole (7); A first intercepting sleeve (8) and a second intercepting sleeve (9) are rotatably mounted in the filter chamber (5), and the surfaces of the first intercepting sleeve (8) and the second intercepting sleeve (9) are both provided with flow guide openings. The first intercepting sleeve (8) controls the opening and closing of the first filter hole (6), and the second intercepting sleeve (9) controls the opening and closing of the second filter hole (7). A pump column (10) is slidably inserted in the inner cylinder (3), a flow channel hole (11) penetrating vertically is provided inside the pump column (10), and a drainage pipe (12) connected to the flow channel hole (11) is installed at the top of the pump column (10); A tunneling drill (13) is rotatably mounted at the bottom end of the drainage cylinder. The tunneling drill (13) comprises a spiral blade (15), an outer cover (16) and a flow guide dividing ring (17). The flow guide dividing ring (17) divides the outer cover (16) into two upper and lower chambers. The spiral blade (15) is fixedly arranged in the lower chamber of the outer cover (16). The central hole of the flow guide dividing ring (17) connects the lower chamber of the outer cover (16) with the inner cylinder (3). A first tooth ring is fixedly arranged on the inner wall of the upper chamber of the outer cover (16). A second toothed ring is fixedly mounted on the surface of the first intercepting sleeve (8), and a third toothed ring is fixedly mounted on the inner wall of the second intercepting sleeve (9); The drainage cylinder is also provided with a driving assembly, which includes a transmission shaft (18), gears, a hydraulic motor (19), a hydraulic cylinder (20) and a shaft sleeve (21). The transmission shaft (18) is rotatably mounted on the mounting plate (1). The transmission shaft (18) passes downward through the filter chamber (5) and extends to the lower side of the partition bottom plate (4). Two gears are fixedly mounted on the surface of the transmission shaft (18). The shaft sleeve (21) is fixedly connected to the upper end of the transmission shaft (18). The hydraulic motor (19) The rotating shaft is slidably inserted into the shaft sleeve (21), and a lifting sleeve (22) is fixedly installed at the telescopic end of the hydraulic cylinder (20). The shaft sleeve (21) is rotatably arranged in the lifting sleeve (22). The hydraulic cylinder (20) controls the transmission shaft (18) to reciprocate up and down, so that one gear meshes with the first gear ring for transmission, or another gear meshes with the second gear ring and the third gear ring for transmission, and the first intercepting sleeve (8), the second intercepting sleeve (9) and the excavation drill (13) are controlled to move through the driving assembly.

2. A drainage structure for foundation pit of civil construction according to claim 1, characterized in that: An exhaust duct (14) is installed on the upper surface of the mounting plate (1), the lower end of the exhaust duct (14) extends into the filter chamber (5), the exhaust duct (14) is externally connected to an air pump, and the filter chamber (5) is filled with filter sand and gravel.

3. A drainage structure for foundation pit of civil construction according to claim 1, characterized in that: An exhaust duct (14) is installed on the upper surface of the mounting plate (1), the lower end of the exhaust duct (14) extends into the filter chamber (5), the exhaust duct (14) is externally connected to a one-way exhaust valve, and the filter chamber (5) is filled with filter sand and gravel.

4. A civil construction foundation pit drainage structure according to claim 1, characterized in that: The excavation drill (13) is rotatably mounted on the lower end of the inner cylinder (3), and the excavation drill (13) is hidden in the lower opening of the outer cylinder (2).

5. A construction method for drainage of a foundation pit for civil construction, using a drainage structure for a foundation pit for civil construction as claimed in any one of claims 1 to 4 for construction, characterized in that: The specific steps include: S1. Installation of drainage cylinders: Before excavation of the foundation pit, reasonably distribute the precipitation points, hoist the drainage cylinders at the precipitation points, and place the drainage cylinders on the ground; S2, excavation of the drainage barrel, the transmission shaft (18) is driven by the hydraulic motor (19), and the excavation drill (13) is driven to rotate, and water is poured into the inner barrel (3). The drill rotates to dig and stir the soil, and the mud is pumped out by the pump, and the drainage barrel gradually sinks and is inserted into the ground; S3, filtering and draining, the pump column (10) is slidably inserted into the inner cylinder (3), and the pump column (10) is lifted and lowered by a hoist, and the pump column (10) moves up and down. When the pump column (10) moves up, there is a large space in the inner cylinder (3), and the groundwater is filtered by the filtering sand and gravel and infiltrates into the inner cylinder (3). When the pump column (10) presses down the seeping water in the drainage cylinder, the water is pressed from the flow channel hole (11) to the drainage pipe (12), and then discharged by the water collection and open drainage method; S4, negative pressure drainage, in the process of drainage in step S3, negative pressure is pumped into the filter chamber (5) to accelerate the seepage of groundwater into the drainage tube, so as to drain the soil in the foundation excavation area; S5, the process of layered excavation of the foundation pit, repeating step S2, with the decrease of the elevation of the bottom surface of the foundation pit excavation, the drainage cylinder is lowered layer by layer.

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