A drill-following pipe-keeping drainage anti-floating pile and a construction method thereof

Abstract

The present application belongs to the technical field of pile foundation construction in building construction, and particularly relates to a drilling and pipe following drainage anti-floating pile and a construction method thereof. The drilling and pipe following drainage anti-floating pile comprises an anti-floating pile, a through channel is formed in the middle of the anti-floating pile along the length direction of the anti-floating pile, and a pipe pile inner cavity is formed; a steel mesh and a pile side grouting pipe are arranged in the pipe wall of the anti-floating pile, a plurality of drainage holes are formed in the pipe wall of the anti-floating pile in a spaced manner, and a water permeable reinforced concrete structure is arranged in the drainage holes. Compared with the prior art, the anti-floating pile is changed from the drilling and pipe following pile into a large-diameter drilling and pipe following drainage anti-floating pile with the drainage function, the pipe pile inner cavity is used as a natural drainage channel, and therefore, a pipe well dewatering does not need to be additionally constructed, and the anti-floating construction cost of the underground structure is greatly saved.

Description

Technical Field

[0001] This invention belongs to the field of pile foundation construction technology in building construction, specifically a drilling and casing drainage anti-buoyancy pile and its construction method. Background Technology

[0002] Pile foundations, as one of the most widely used foundation types in deep foundation engineering, play an excellent role in transferring loads from the superstructure, resisting buoyancy of underground structures, and reducing superstructure settlement. Currently, steel piles, bored cast-in-place piles, and PHC pipe piles are the three most common types of pile foundations. Among them, steel piles have a high overall construction cost and face the technical challenge of poor corrosion resistance. Bored cast-in-place piles have advantages such as large pile diameter, high bearing capacity, and high degree of mechanized construction. However, their construction process of drilling first and then grouting, as well as using mud slurry for wall protection, is prone to defects such as hole collapse, mud inclusion, faulting, and duct blockage. Ultimately, this leads to problems such as easy mud inclusion in the pile body, insufficient pile strength, and insufficient pile side friction. At the same time, the construction of bored cast-in-place piles involves the discharge of a large amount of mud, which can easily cause environmental pollution. In comparison, PHC pipe piles have significant advantages in terms of pile strength, construction speed, prefabricated integrated construction, on-site management, and construction period. However, due to the limitations of traditional pile driving methods such as hammer driving and static pressure driving, their pile diameter is generally less than 800mm, and the pile tip is difficult to embed into medium-to-slightly weathered rock layers. As a result, the bearing capacity of a single pile is generally no more than 3500kN. Furthermore, the harsh pile driving methods such as hammer driving and static pressure driving are prone to causing pile defects. 70% of the existing pipe piles have a vertical bearing capacity of less than 50% of the pile strength, which indicates that the high strength of the pipe pile material has not been fully utilized.

[0003] In order to expand the pile diameter, bearing capacity and geological applicability of PHC pipe piles, my country has independently developed a construction method for large-diameter drilling pipe piles (a construction method for drilling pipe piles for building or bridge foundations, patent number: 200710029023.5, authorization announcement number: CN101122130B). Drilling-while-driving (DWDD) pipe piles are a new type of energy-saving and environmentally friendly large-diameter (800mm~1400mm) non-displacement PHC pipe pile constructed simultaneously through drilling, pile driving, and soil removal, without mud discharge. The borehole diameter of DWDD pipe piles is approximately 20mm larger than the pile's outer diameter. Therefore, the pile body does not directly contact the soil; instead, a gap of about 10mm thickness (referred to as the "pile-soil gap") is formed between the borehole wall and the outer wall of the DWDD pipe pile. After pile driving, grout is injected into this "pile-soil gap" through a grouting pipe pre-embedded inside the pile body, thereby increasing the pile's side friction resistance. The pile tip of the DWDD pipe pile can be embedded more than 0.5m into moderately weathered rock layers, significantly increasing the pile tip resistance. The vertical bearing capacity of a single DWDD pipe pile can reach 23000kN, which is 6.57 times that of traditional small- and medium-diameter pipe piles. The drilling and pipe pile construction technology solves the problem of pile driving caused by the large diameter of PHC pipe piles or hard soil layers. It overcomes the problems of limited PHC pipe pile diameter, construction noise pollution, and easy defects in the pile body caused by traditional PHC pipe pile construction methods such as hammer driving and static pressure methods. It greatly improves the bearing capacity of PHC pipe piles and can well meet the needs of large-scale infrastructure construction such as port terminals, long-span bridges, and super high-rise buildings at present.

[0004] However, practical experience shows that the ultimate bearing capacity of single piles in drilling-while-conducting piles varies from 15,000 kN to 23,000 kN. This difference in bearing capacity mainly stems from the grouting effect in the pile-soil gap and the rock-embedded effect at the pile tip. For drilling-while-conducting piles, after pile driving, grouting is directly performed using grouting pipes pre-embedded in the pipe wall, neglecting the influence of groundwater in the pile-soil gap on the physical and mechanical properties of the grout. Groundwater in the pile-soil gap dilutes the grout, severely affecting its normal solidification. Furthermore, the flow of groundwater in the pile-soil gap carries away some of the grout, resulting in significant differences in the grouting effect and uneven pile-side friction after pile formation. Consequently, the design value of the single pile bearing capacity of drilling-while-conducting piles generally does not exceed 15,000 kN, failing to fully utilize the ultra-high bearing capacity advantage of these piles and causing a significant waste of resources. Therefore, quickly clearing groundwater from the pile-soil gap is crucial for maximizing the pile-side friction of drilling-while-conducting piles.

[0005] Construction along rivers, coastlines, lakes, and streams presents significant challenges due to high groundwater levels, leading to difficulties in dewatering, high anti-buoyancy costs, and lengthy foundation treatment cycles. Therefore, research on underground anti-buoyancy has always been a hot and challenging issue. Currently, various anti-buoyancy measures exist, primarily including passive anti-buoyancy (e.g., anti-buoyancy anchor bolts and anti-buoyancy piles) and active anti-buoyancy (modifying the groundwater environment). Generally, both anti-buoyancy anchor bolts and anti-buoyancy piles achieve good results, but neither can be used in soft rock and soil, and both present durability and corrosion resistance issues. The increased number of anchors and bolts significantly increases construction costs. Active anti-buoyancy measures such as drainage depressurization and water-stop depressurization are effective, but they all require additional well dewatering, undoubtedly increasing foundation construction costs. If existing pile foundations could be modified into drainage-resistant anti-buoyancy pile foundations with drainage functions without affecting the bearing capacity of the existing pile foundations, thus replacing well dewatering, it would greatly reduce the construction costs of wells. It is worth noting that while there are many existing achievements related to drainage piles, most of these drainage piles address the "excess pore water pressure problem." When precast piles are driven into the ground using traditional pile driving methods such as hammer driving and static pressure methods, the soil will squeeze around the precast pile, causing the water pressure in the soil layer to increase. If the construction area contains a large amount of groundwater and the soil layer has poor permeability, excess pore water pressure can easily form on the pile side, greatly reducing the pile side friction of traditional PHC pipe piles. Therefore, most existing drainage piles open several drainage outlets on the side wall of the pile body to reduce and eliminate pore water pressure in the soil. Moreover, the drainage outlets are easily blocked by soil particles under strong squeezing force during the pile driving process. Therefore, drainage piles in the traditional sense can only eliminate excess pore water pressure in the soil layer around the pile and do not have the effect of truly preventing the main structure of the project from floating.

[0006] In addition, drilling-while-conduit piles are a new type of non-displacement rock-embedded pipe pile foundation. They have superior vertical compressive bearing capacity of single piles, but their tensile bearing capacity is slightly insufficient. If the drilling-while-conduit piles can be transformed into large-diameter drilling-while-conduit drainage anti-buoyancy piles with drainage function, while increasing their tensile strength, the overall cost of single pile construction will be greatly reduced, thereby improving the engineering application value of large-diameter drilling-while-conduit drainage anti-buoyancy piles.

[0007] Therefore, there is an urgent need to research and develop a new type of drilling-while-drilling drainage anti-buoyancy pile and its construction method to overcome the above-mentioned defects. Summary of the Invention

[0008] The first objective of this invention is to provide a drilling and casing drainage anti-buoyancy pile, which transforms the drilling and casing pile into a large-diameter drilling and casing drainage anti-buoyancy pile with drainage function. By using the inner cavity of the pipe pile as a natural drainage channel, it is not necessary to build additional pipe wells for dewatering, which greatly saves the construction cost of anti-buoyancy construction of underground structures.

[0009] The present invention adopts the following technical solution: a drilling and casing drainage anti-buoyancy pile, which includes an anti-buoyancy pile, a through channel is opened in the middle of the anti-buoyancy pile along its length to form a pipe pile cavity; a steel mesh and a pile side grouting pipe are provided in the pipe wall of the anti-buoyancy pile, and a number of drainage holes are formed on the pipe wall of the anti-buoyancy pile at intervals, and a permeable reinforced concrete structure is built into the drainage holes.

[0010] A steel structure is installed on the inner wall of the drainage hole, and the steel structure at the drainage hole wall is fixedly connected to the steel mesh inside the pipe wall by steel bar connecting ribs.

[0011] Furthermore, a pile shoe is provided at the end of the anti-buoyancy pile.

[0012] Furthermore, the drainage hole has a stepped cylindrical wall, including an inner wall and an outer wall. The inner wall is located near the inner cavity of the pipe pile, and the cross-sectional diameter of the inner wall is larger than that of the outer wall, and the length of the inner wall is greater than that of the outer wall.

[0013] Furthermore, the permeable reinforced concrete structure includes a permeable reinforced concrete upper structure and a permeable reinforced concrete lower structure; wherein, the diameter and length of the permeable reinforced concrete upper structure are matched with the diameter and length of the inner hole wall; the diameter and length of the permeable reinforced concrete lower structure are matched with the diameter and length of the outer hole wall, forming a first permeable reinforced concrete structure, so as to realize the docking installation of the first permeable reinforced concrete structure and the drainage hole;

[0014] And / or the permeable reinforced concrete structure includes a permeable reinforced concrete upper structure and a permeable reinforced concrete lower structure; wherein the diameter and length of the permeable reinforced concrete upper structure are matched with the diameter and length of the inner hole wall; the diameter of the permeable reinforced concrete lower structure is matched with the diameter of the outer hole wall, and the length of the permeable reinforced concrete lower structure is greater than the length of the outer hole wall, forming a second permeable reinforced concrete structure to achieve the docking installation of the second permeable reinforced concrete structure and the drainage hole.

[0015] Compared with the prior art, the beneficial effects of the drilling-while-drilling drainage anti-buoyancy pile in this invention are as follows:

[0016] This invention relates to a drilling-while-conduit (DWC) drainage anti-buoyancy pile, which transforms the DWC pile into a large-diameter DWC drainage anti-buoyancy pile with drainage function. Utilizing the inner cavity of the pile as a natural drainage channel eliminates the need for constructing additional wells for dewatering, significantly reducing the cost of anti-buoyancy construction for underground structures. Simultaneously, a reinforcing mesh is installed inside the pipe wall, and the grouting pipes on the pile side are bound and fixed to the mesh, enhancing the overall connection strength. Furthermore, drainage holes are provided on the pipe wall of the anti-buoyancy pile, and permeable reinforced concrete structures are embedded within these holes to achieve the drainage function.

[0017] The second objective of this invention is to provide a construction method for a drilling-while-drilling drainage anti-buoyancy pile, which includes the following steps:

[0018] S01: Fabrication of Drilling-while-conduit drainage anti-buoyancy piles: Based on the preliminary geological survey, determine the soil layer information and groundwater occurrence information, design the number and location of drainage holes for the drilling-while-conduit drainage anti-buoyancy piles, and fabricate the drilling-while-conduit drainage anti-buoyancy piles, as well as the first permeable reinforced concrete structure and the second permeable reinforced concrete structure installed in the drilling-while-conduit drainage anti-buoyancy piles according to actual needs.

[0019] S02: Pile driving: After determining the pile position, insert the first permeable reinforced concrete structure into the drainage hole of the drilling and casing drainage anti-buoyancy pile, and lock the first permeable reinforced concrete structure.

[0020] Subsequently, a drilling and casing pile driving machine was used to drive the drilling and casing drainage anti-buoyancy piles. The enlarged drill bit and the long spiral drill rod entered the soil layer through the inner cavity of the drilling and casing drainage anti-buoyancy pile to drill, so that there is a "pile-soil gap" between the drilling and casing drainage anti-buoyancy pile and the surrounding soil.

[0021] After the reaming drill bit is drilled into the hole, the drilling-while-drilling drainage anti-buoyancy pile sinks synchronously with the reaming drill bit. When the first section of the drilling-while-drilling drainage anti-buoyancy pile sinks to the depth of the pile top from the ground that meets the design requirements, the first section of the drilling-while-drilling drainage anti-buoyancy pile is clamped with a pile clamping device to perform pile splicing and drill rod extension. At the same time, the grouting pipes on the pile sides of the upper and lower anti-buoyancy piles are connected, and then drilling continues until the reaming drill bit enters the interior of the medium and slightly weathered rock layer by more than 0.5m.

[0022] S03: The pile end is sealed with fine stone concrete: After drilling to the design depth, the long spiral drill rod and the reaming drill bit are withdrawn from the inner cavity of the pipe pile. Then, the slag removal bucket is inserted into the pile end through the inner cavity of the pipe pile of the pipe-following drainage anti-buoyancy pile to remove the pile end sediment and pile end mud and water. Then, the steel guide pipe is lowered to near the bottom surface of the pile and fine stone concrete is poured.

[0023] S04: Drive piles to moderately weathered rock strata: After the fine stone concrete is poured, the pile end of the drilling and casing drainage anti-buoyancy pile is pressed down by the drilling and casing pile machine, and the pile end of the drilling and casing drainage anti-buoyancy pile is pressed into the bottom of the hole, so that it is cemented into a whole with the moderately weathered rock strata under the action of the fine stone concrete.

[0024] S05: Drainage of the pile-soil gap: During the process of filling the pile end with fine stone concrete to seal the bottom and driving the pile to the medium and slightly weathered rock layer, groundwater gradually gathers into the pile-soil gap and flows into the inner cavity of the pipe pile through the first permeable reinforced concrete structure set in the anti-buoyancy pile, and the water in the inner cavity of the pipe pile is discharged through the drainage pipe.

[0025] S06: Grouting of the "pile-soil gap": After most of the water in the "pile-soil gap" has been drained, grouting is carried out on the pile side. At this time, except for retaining two drainage pipes, the entire drainage system is dismantled and moved to the next pile position for later use.

[0026] According to the water-cement ratio designed for pile side grouting, the grouting liquid is prepared in the mixing tank. After the grouting liquid is mixed evenly, it is injected into the "pile-soil gap" through the grouting pump and the pile side grouting pipe pre-embedded in the pipe pile.

[0027] S07: Replace the first permeable reinforced concrete structure with the second permeable reinforced concrete structure: After the grouting body on the pile side meets the strength requirements, remove the first permeable reinforced concrete structure and continue drilling into the soil through the drainage hole. Then, insert the second permeable reinforced concrete structure into the drainage hole and enter the soil.

[0028] S08: Casting the pile cap and exerting anti-buoyancy capability: Subsequently, the pile cap is cast, the drainage pipe pre-reserved in the inner cavity of the pipe pile is cast into the pile cap, and a drainage outlet is reserved on the side wall of the pile cap.

[0029] Furthermore, during the construction of the entire foundation and superstructure, a multi-functional pump is used to apply negative pressure to the inner cavity of the pipe pile through the drainage outlet and drainage pipe. Under the action of negative pressure, groundwater flows into the inner cavity of the pipe pile through the second permeable reinforced concrete structure, and the groundwater in the inner cavity of the pipe pile is extracted through the drainage pipe.

[0030] Furthermore, if groundwater is abundant and cannot be completely removed by natural drainage in step S05, then negative pressure treatment is applied to the inner cavity of the pipe pile after completing step S05.

[0031] Furthermore, a layer of rubber rings is laid on the end plate of the drilling and casing drainage anti-buoyancy pile, and then the cover plate is fixed to the end plate to seal the inner cavity of the pipe pile; at this time, the vacuum pump is started, and the pressure value in the inner cavity of the pipe pile is monitored in real time by the pressure gauge to complete the negative pressure treatment of the inner cavity of the pipe pile.

[0032] Compared with the prior art, the beneficial effects of the construction method of the drilling-while-drilling drainage anti-buoyancy pile in this invention are as follows:

[0033] 1) The construction method of the drilling and casing drainage anti-buoyancy pile of the present invention has a simple construction procedure, low construction cost, high degree of mechanization, and safety and reliability. It can be applied to the construction of strata with abundant groundwater, and provides technical support and guarantee for the anti-buoyancy of underground structures.

[0034] 2) This construction method involves setting up a first permeable reinforced concrete structure with a variable diameter and a length equal to the wall thickness of the pipe pile at the designed location of the large-diameter drilling and casing drainage anti-buoyancy pile. This ensures smooth pile driving while introducing groundwater from the pile-soil gap and surrounding soil into the inner cavity of the pipe pile and the bottom of the borehole. The presence of groundwater at the bottom of the borehole can reduce the temperature of the reaming drill bit, increase its service life, and soften the soil, thereby accelerating drilling efficiency. The presence of groundwater in the inner cavity of the pipe pile can lubricate the long spiral drill rod and the excavated soil to be removed from the inner cavity of the pipe pile, increasing soil removal efficiency, improving soil removal effect, reducing soil removal resistance, and saving power costs.

[0035] 3) Correspondingly, after the "pile-soil gap" is formed and before grouting, a multi-functional vacuum pump is used to change the inner cavity of the pipe pile to a negative pressure state. Through the prefabricated permeable reinforced concrete structure of the pile body, the groundwater in the "pile-soil gap" and the surrounding soil within a certain range is discharged into the inner cavity of the pipe pile, creating a short-term waterless environment in the "pile-soil gap". This greatly reduces the dilution effect of the groundwater in the "pile-soil gap" on the grouting fluid, ensuring the original physical and mechanical properties of the grouting fluid, thereby improving the grouting effect and the frictional resistance of the pile side. At the same time, after the groundwater is discharged into the inner cavity of the pipe pile, it is pumped out to the ground water storage tank and mixing tank, which can be used to prepare the grouting fluid, greatly saving water.

[0036] 4) After the grout in the pile-soil gap solidifies, the first permeable reinforced concrete structure with a variable diameter and a length equal to the thickness of the pipe pile wall is replaced with a second permeable reinforced concrete structure with a variable diameter but a length several times the thickness of the pipe pile wall. The second permeable reinforced concrete structure penetrates to a certain depth into the soil around the pile after passing through the pipe pile wall, which can greatly increase the side friction resistance of the pile foundation, thereby greatly improving the bearing capacity of the drilling and pipe-following drainage anti-buoyancy pile, especially the vertical pull-out bearing capacity of a single pile, and ultimately greatly improving the anti-buoyancy capacity of the pile foundation.

[0037] 5) The second permeable reinforced concrete structure that enters a certain depth into the soil around the pile can drain the groundwater in the soil around the pile into the inner cavity of the pipe pile. When the pile foundation is poured, several drainage pipes are reserved in the inner cavity of the pipe pile. Finally, the groundwater in the inner cavity of the pipe pile can be continuously pumped to the ground water storage tank for later use. This can achieve the purpose of lowering the groundwater level during the entire construction process, so as to realize the anti-buoyancy function of the underground structure. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This is a schematic diagram of the overall structure of the drilling and casing drainage anti-buoyancy pile;

[0040] Figure 2 for Figure 1 Schematic diagram of the overall structure of the central drainage hole;

[0041] Figure 3 for Figure 1 Schematic diagram of the overall structure of the permeable reinforced concrete structure;

[0042] Figure 4 This is a schematic diagram of a drilling and casing drainage anti-buoyancy pile being driven.

[0043] Figure 5 A schematic diagram of the drilling and casing drainage anti-buoyancy pile driving into the rock and the drainage of the "pile-soil gap";

[0044] Figure 6 A schematic diagram of grouting for the "pile-soil gap" of a drilling and casing drainage anti-buoyancy pile;

[0045] Figure 7 A schematic diagram showing the replacement of the first permeable reinforced concrete structure with the second permeable reinforced concrete structure;

[0046] Figure 8 A schematic diagram of the overall anti-buoyancy structure of a drilling-while-drilling drainage anti-buoyancy pile with a pile foundation cap;

[0047] Among them: 1. Drilling-while-following drainage anti-buoyancy pile; 2. Reinforcing mesh; 3. Pile side grouting pipe; 4. Pipe wall; 5. Pipe pile inner cavity; 6. Drainage hole; 7. Hole wall; 8. Reinforcing steel connecting rib; 9. Grout outlet; 10. Pile shoe; 11. Inner hole wall; 12. Outer hole wall; 13. Permeable reinforced concrete structure; 13-1 first permeable reinforced concrete structure; 13-2 second permeable reinforced concrete structure; 14. Permeable reinforced concrete upper structure; 15. Permeable reinforced concrete lower structure; 16. Pin; Drill-while-following pipe pile. 17. Piling machine, 18. Reamer bit, 19. Soil around the pile, 20. "Pile-soil gap", 21. Long spiral drill rod, 22. Pile clamp, 23. Medium to slightly weathered rock layer, 24. Fine aggregate concrete, 25. Stratum, 26. Groundwater, 27. Drainage pipe, 28. End plate, 29. Rubber ring, 30. Cover plate, 31. Vacuum pump, 32. Water storage tank, 33. Pressure gauge, 34. Control valve, 35. Water outlet, 36. Mixing tank, 37. Grouting fluid, 38. Grouting pump, 39. Pile foundation cap, 40. Drainage outlet. Detailed Implementation

[0048] The technical solutions in 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 some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0049] The following is in conjunction with the appendix Figure 1 To be continued Figure 8 The invention is described in detail with specific embodiments:

[0050] like Figure 1-8 As shown, this invention provides a drilling-while-conducting drainage anti-buoyancy pile, which includes an anti-buoyancy pile 1. A through channel is opened in the middle of the anti-buoyancy pile 1 along its length to form a pipe pile cavity 5. The pipe pile cavity 5 is a hollow structure and can be filled as needed. Since the drilling-while-conducting pile has a large diameter and high bearing capacity, and the pipe pile cavity 5 has a large space, generally with a diameter of over 800mm, the pipe pile cavity 5 is a natural drainage channel. Therefore, this invention transforms the drilling-while-conducting pile into a large-diameter drilling-while-conducting drainage anti-buoyancy pile 1 with drainage function, eliminating the need to construct additional wells for dewatering and greatly saving the anti-buoyancy construction cost of underground structures.

[0051] Meanwhile, a steel mesh 2 and a pile-side grouting pipe 3 are installed inside the pipe wall 4 of the anti-buoyancy pile 1, and the pile-side grouting pipe 3 is tied to the steel mesh 2 inside the anti-buoyancy pile 1 with binding straps, etc. Since the pipe wall 4 of the anti-buoyancy pile 1 has a certain thickness, the pile-side grouting pipe 3 can be embedded in it; the pile-side grouting pipe 3 is provided with several grout outlets 9, which are located at the designed position of the pile body of the anti-buoyancy pile 1. The specific design can be made by those skilled in the art based on the actual situation.

[0052] Furthermore, the anti-buoyancy pile 1 has several spaced drainage holes 6 formed on its pipe wall 4. During the prefabrication of the anti-buoyancy pile 1, the positions of the drainage holes 6 are reserved according to the design requirements. These drainage holes 6 are through holes, and a permeable reinforced concrete structure 13 is built into each drainage hole 6 to achieve drainage. Correspondingly, the drainage holes 6 can be arranged along the pile body in an S-shape, quincunx shape, or other combination, and the specific arrangement and number of drainage holes 6 can be determined according to the geological conditions and groundwater conditions. To improve the strength of the pile body at the location of the drainage holes 6, a steel structure is installed on the inner wall surface of the drainage hole 6 wall 7, making the drainage hole 6 wall 7 a steel structure with a certain thickness and rigidity. The steel structure at the drainage hole 6 wall 7 is fixedly connected to the steel mesh 2 inside the pipe wall 4 through steel connecting ribs 8 and welded into an integral structure, further improving the strength of the anti-buoyancy pile 1.

[0053] This invention relates to a drilling-while-conduit drainage anti-buoyancy pile, which transforms the drilling-while-conduit pile into a large-diameter drilling-while-conduit drainage anti-buoyancy pile 1 with drainage function. Utilizing the inner cavity 5 of the pile as a natural drainage channel eliminates the need for constructing additional wells for dewatering, significantly reducing the construction cost of anti-buoyancy structures underground. Simultaneously, a reinforcing mesh 2 is installed inside the pipe wall 4, and the pile-side grouting pipe 3 is tied and fixed to the reinforcing mesh 2, enhancing the overall connection strength. Furthermore, drainage holes 6 are provided on the pipe wall 4 of the anti-buoyancy pile 1, and a permeable reinforced concrete structure 13 is embedded within the drainage holes 6 to achieve the drainage function.

[0054] Furthermore, in order to ensure that the soil removal operation can be carried out smoothly during the pile driving process of the anti-buoyancy pile 1, a pile shoe 10 can be provided at the end of the anti-buoyancy pile 1.

[0055] Furthermore, the drainage hole 6 has a stepped cylindrical wall 7, comprising an inner wall 11 and an outer wall 12. The inner wall 11 is located near the inner cavity of the pipe pile, and the cross-sectional diameter of the inner wall 11 is larger than the cross-sectional diameter of the outer wall 12. The length of the inner wall 11 is also greater than the length of the outer wall 12. In this embodiment, the cross-sectional diameter of the inner wall 11 is approximately 5 mm larger than the cross-sectional diameter of the outer wall 12; the length of the outer wall 12 is approximately 10 mm smaller, and the sum of the lengths of the inner wall 11 and the outer wall 12 is equal to the thickness of the pipe wall 4.

[0056] Correspondingly, the permeable reinforced concrete structure 13 includes a permeable reinforced concrete upper structure 14 and a permeable reinforced concrete lower structure 15. The diameter and length of the permeable reinforced concrete upper structure 14 match the diameter and length of the inner hole wall 11; the diameter and length of the permeable reinforced concrete lower structure 15 match the diameter and length of the outer hole wall 12, forming a first permeable reinforced concrete structure 13-1, which can be seamlessly installed into the drainage hole 6.

[0057] Of course, there are two models of the permeable reinforced concrete structure 13. The second model adopts the following design: the permeable reinforced concrete structure 13 includes a permeable reinforced concrete upper structure 14 and a permeable reinforced concrete lower structure 15. The diameter and length of the permeable reinforced concrete upper structure 14 match the diameter and length of the inner borehole wall 11; the diameter of the permeable reinforced concrete lower structure 15 matches the diameter of the outer borehole wall 12, and the length of the permeable reinforced concrete lower structure 15 is much greater than the length of the outer borehole wall 12, forming a second permeable reinforced concrete structure 13-2. This allows the second permeable reinforced concrete structure 13-2 to be connected and installed with the drainage hole 6. In this way, the permeable reinforced concrete lower structure 15 can extend into the soil to a certain length, enhancing the drainage effect. Simultaneously, the reinforced concrete structure extending into the soil also greatly increases the vertical compressive bearing capacity and vertical tensile bearing capacity of the drilling and casing drainage anti-buoyancy pile 1. In this embodiment, the length of the permeable reinforced concrete lower structure 15 is much greater than the length of the outer borehole wall 12, and is set to be about 1 to 3 times the wall thickness of the pipe wall 4 of the anti-buoyancy pile 1.

[0058] Furthermore, a slot can be formed on the side of the drainage hole 6 near the inner cavity of the pipe pile, and a locking element can be installed in the slot to lock the permeable reinforced concrete structure 13. In this embodiment, the locking element can be a pin 16 or other connecting element that can lock and fix the permeable reinforced concrete structure 13. The other end of the permeable reinforced concrete structure 13 is held in place by the hole wall 7 of the variable cross-section drainage hole 6, which prevents the permeable reinforced concrete structure 13 from swinging left and right.

[0059] Correspondingly, the permeable reinforced concrete structure 13 is composed of steel bars and permeable concrete. The pores of the concrete gradually increase along the direction of the inner cavity 5 of the pipe pile towards the soil, which is conducive to the smooth drainage of groundwater in the "pile-soil gap" into the inner cavity 5 of the pipe pile.

[0060] Based on the aforementioned type of drilling-while-conducting drainage anti-buoyancy pile, this invention addresses the problems of groundwater in the "pile-soil gap" during the construction of existing drilling-while-conducting pile technology, which dilutes the grouting fluid and leads to poor grouting effect on the pile side; high vertical compressive bearing capacity but insufficient tensile bearing capacity of single piles in drilling-while-conducting piles; and high construction costs for additional wells for dewatering underground structures to prevent buoyancy. The invention also provides a construction method for drilling-while-conducting drainage anti-buoyancy piles, comprising the following steps:

[0061] S01: Fabrication of Drilling-while-conduit drainage anti-buoyancy pile 1: Based on the preliminary geological survey, determine the soil layer information and groundwater occurrence information, and design the number and location of drainage holes 6 of the drilling-while-conduit drainage anti-buoyancy pile 1. According to actual needs, fabricate the drilling-while-conduit drainage anti-buoyancy pile 1, as well as the first permeable reinforced concrete structure 13-1 and the second permeable reinforced concrete structure 13-2 installed in the drilling-while-conduit drainage anti-buoyancy pile 1, and transport them to the site of the pile driving hole for later use.

[0062] S02: Pile driving: After determining the pile position, insert the first permeable reinforced concrete structure 13-1 into the drainage hole 6 of the drilling and pipe-following anti-buoyancy pile 1, and insert locking parts such as pins 16 into the slot to lock the first permeable reinforced concrete structure 13-1.

[0063] Subsequently, the drilling and casing pile driving machine 17 was used to drive the drilling and casing drainage anti-buoyancy pile 1. The reaming drill bit 18 and the long spiral drill rod 21 entered the soil layer through the inner cavity 5 of the casing pile 1 to drill. The diameter of the drill hole formed by the reaming drill bit 18 is about 20mm larger than the outer diameter of the drilling and casing drainage anti-buoyancy pile 1, so that there is a "pile-soil gap" 20 between the drilling and casing drainage anti-buoyancy pile 1 and the surrounding soil 19. The thickness of the "pile-soil gap" is about 10mm.

[0064] After the reaming drill bit 18 drills into the hole, approximately 2-5 meters in depth, the drilling-while-drilling drainage anti-buoyancy pile 1 sinks synchronously with the reaming drill bit 18 (i.e., the reaming drill bit 18 is 2-5 meters ahead of the pile end of the drilling-while-drilling drainage anti-buoyancy pile 1). The soil and rock debris generated during drilling will be discharged to the pile end through the long spiral drill rod 21 in the inner cavity 5 of the pipe pile. When the first section of the drilling-while-drilling drainage anti-buoyancy pile 1 sinks to the depth of the pile top from the ground that meets the design requirements (in this embodiment, the design requirement is that the pile top sinks to approximately 2 meters from the ground), the first section of the drilling-while-drilling drainage anti-buoyancy pile 1 is clamped with the pile clamping device 22 to perform pile splicing and lengthen the drill rod. At the same time, the grouting pipes 3 on the pile sides of the upper and lower anti-buoyancy piles 1 are connected, and drilling continues until the reaming drill bit enters more than 0.5 meters into the interior of the medium-to-micro-weathered rock layer.

[0065] Correspondingly, during the pile driving process, groundwater in the soil on the side of the pile can enter the inner cavity 5 of the pipe pile through the first permeable reinforced concrete structure 13-1, and then flow into the bottom of the hole. The presence of groundwater can cool the reaming drill bit 18, lubricate the long spiral drill rod 21, and soften the soil at the bottom of the hole, thereby reducing drilling resistance, improving drilling efficiency, and saving construction costs.

[0066] S03: The pile end is sealed with fine stone concrete: After drilling to the design depth, reverse the long spiral drill rod 21 to retract the reaming drill bit 18, and withdraw the long spiral drill rod 21 and the reaming drill bit 18 from the inner cavity 5 of the pipe pile. Then, extend the slag removal bucket into the pile end through the inner cavity 5 of the pipe pile of the drilling and pipe-following drainage anti-buoyancy pile 1 to remove the pile end sediment and pile end mud water of the drilling and pipe-following drainage anti-buoyancy pile 1. Then, lower the steel guide pipe to about 500mm close to the bottom surface of the pile and pour fine stone concrete 24. The height of the fine stone concrete 24 is generally 2 to 3m.

[0067] S04: Pile driving to moderately weathered rock strata: Since the reaming drill bit 18 is 2-5m ahead of the pile tip of the drilling and casing drainage anti-buoyancy pile 1, after the fine aggregate concrete 24 is poured, the pile tip of the drilling and casing drainage anti-buoyancy pile 1 will be pressed down by the drilling and casing pile machine 17. The downward pressure of the drilling and casing pile machine 17 can reach 10 tons, which is sufficient to press the pile tip of the drilling and casing drainage anti-buoyancy pile 1 into the bottom of the hole. Under the action of the fine aggregate concrete 24, it will be cemented into a whole with the moderately weathered rock strata 23, greatly improving the pile tip force. Since subsequent construction processes do not require pile driving, after the pile driving is completed, the drilling and casing pile machine 17 and all its supporting equipment (including the reaming drill bit 18, long spiral drill rod 21, etc.) can be moved to the next pile location for pile driving construction, which can greatly improve the pile driving efficiency and increase the utilization rate of large equipment, thereby achieving the effect of shortening the construction period and saving construction costs.

[0068] S05: Drainage of the "Pile-Soil Gap": During the process of grouting fine stone concrete to seal the bottom of the pile tip and driving the pile into the moderately weathered rock layer, groundwater 26 gradually gathers into the "pile-soil gap" 20 and flows into the inner cavity 5 of the pipe pile through the first permeable reinforced concrete structure 13-1 set in the anti-buoyancy pile 1. The water in the inner cavity 5 of the pipe pile can be discharged through the drainage pipe 27, thereby reducing or even eliminating the water in the "pile-soil gap" 20. Specifically, multiple drainage pipes 27 can be set in the inner cavity 5 of the pipe pile. The lengths of the multiple drainage pipes 27 are different, and they can differ by 3 to 5 meters. The end of the longest drainage pipe 27 should be about 0.5 meters away from the fine stone concrete 24 sealing the bottom of the pile tip.

[0069] Of course, if groundwater is abundant and natural drainage in step S05 is insufficient to completely remove it, then after completing step S05, negative pressure treatment should be applied to the inner cavity 5 of the pipe pile to create negative pressure and promote drainage. Specifically, the following implementation method can be used:

[0070] An end plate 28 is installed on top of the drilling and casing drainage anti-buoyancy pile 1, and a layer of rubber ring 29 is laid on the end plate 28. Then, the cover plate 30 is fixed to the end plate 28 with bolts to seal the inner cavity 5 of the pipe pile. At this time, the multi-functional vacuum pump 31 is started, and the pressure value in the inner cavity 5 of the pipe pile is monitored in real time by the pressure gauge 33 to complete the negative pressure treatment of the inner cavity 5 of the pipe pile. The pressure is controlled by the control valve 34 to prevent the negative pressure from damaging the "pile-soil gap" 20. In this way, the water in the "pile-soil gap" 20 can be greatly reduced or even eliminated. Finally, the extracted groundwater is temporarily stored in the water storage tank 32 for later use.

[0071] After the drilling and casing drainage anti-buoyancy pile 1 is driven, the groundwater in the "pile-soil gap" 20 is quickly cleared to reduce the dilution of the grouting fluid on the pile side by the groundwater in the "pile-soil gap" 20, ensure the normal solidification of the grouting body on the pile side, and thus improve the pile side friction resistance.

[0072] S06: Grouting of the "Pile-Soil Gap": After most of the water in the "Pile-Soil Gap" 20 has been drained, grouting is carried out on the pile side. At this time, except for retaining two drainage pipes 27, the entire drainage system is dismantled and moved to the next pile position for backup. At this time, the pressure in the inner cavity 5 of the pipe pile changes from negative pressure to normal atmospheric pressure, which can prevent groundwater in the stratum 25 from flowing back into the "Pile-Soil Gap" 20, thereby ensuring that there is no groundwater in the "Pile-Soil Gap" 20 for a considerable period of time, providing sufficient time for grouting on the pile side.

[0073] Subsequently, the water in the water storage tank 32 is discharged into the mixing tank 36 through the outlet 35. According to the water-cement ratio designed for pile side grouting, the grouting fluid 37 is prepared in the mixing tank 36. After the grouting fluid 37 is mixed evenly, it is injected into the "pile-soil gap" 20 through the grouting pump 38 and the pile side grouting pipe 3 embedded in the pipe pile. The grouting fluid 37 avoids the dilution effect of groundwater in a waterless environment, ensuring the original physical and mechanical properties, thereby improving the pile side grouting effect and pile side friction resistance, and improving the pull-out performance of the drilling and pipe-following drainage anti-buoyancy pile 1.

[0074] S07: Replace the first permeable reinforced concrete structure 13-1 with the second permeable reinforced concrete structure 13-2: After the grouting material on the pile side meets the strength requirements, the first permeable reinforced concrete structure 13-1 has lost its permeability because its outer side is wrapped by the grouting material. Therefore, it can be inserted into the pipe pile through the inner cavity 5 and removed using a regular electric drill. At the same time, continue drilling into the soil to a certain depth through the drainage hole 6, and then insert the extended version of the second permeable reinforced concrete structure 13-2 into the drainage hole 6 and into the soil to a certain depth, thereby restoring the permeability of the drainage hole 6. Correspondingly, the extended version of the second permeable reinforced concrete structure 13-2 with reinforced concrete structure, after entering the soil to a certain depth, will greatly increase the frictional resistance of the pile foundation, thereby greatly improving the vertical compressive bearing capacity and vertical tensile bearing capacity of the single pile, and greatly increasing the anti-buoyancy capacity of the drilling and pipe-following drainage anti-buoyancy pile 1. Meanwhile, after the grouting body of the drilling and casing drainage anti-buoyancy pile 1 reaches a certain strength, it is modified so that it can also perform drainage function without the need to build additional wells for dewatering, thereby achieving anti-buoyancy of underground structures.

[0075] S08: Casting the pile cap and exerting anti-buoyancy capability: Subsequently, the pile cap 39 is cast, and the drainage pipe 27 pre-reserved in the inner cavity 5 of the pipe pile is cast into the pile cap 39, with a drainage outlet 40 reserved on the side wall of the pile cap 39. Correspondingly, during the entire foundation and superstructure construction process, a multi-functional vacuum pump can be used to apply negative pressure to the inner cavity 5 of the pipe pile through the drainage outlet 40 and the drainage pipe 27. Under the action of negative pressure, groundwater 26 flows into the inner cavity 5 of the pipe pile through the second permeable reinforced concrete structure 13-2. After the groundwater in the inner cavity 5 of the pipe pile accumulates to a certain volume, it is pumped out to the ground surface through the drainage pipe 27, thereby achieving the purpose of lowering the groundwater level and realizing the anti-buoyancy function.

[0076] In summary, the construction method of the drilling and casing drainage anti-buoyancy pile of the present invention has a simple construction procedure, low construction cost, high degree of mechanization, and is safe and reliable. It can be applied to the construction of strata with abundant groundwater, and provides technical support and guarantee for the anti-buoyancy of underground structures.

[0077] This construction method involves setting up a first permeable reinforced concrete structure with a variable diameter and a length equal to the wall thickness of the pipe pile at the designed location of the large-diameter drilling and casing drainage anti-buoyancy pile 1. This ensures smooth pile driving while introducing groundwater from the pile-soil gap 20 and the surrounding soil 19 into the inner cavity 5 of the pipe pile and the bottom of the borehole. The presence of groundwater at the bottom of the borehole can reduce the temperature of the reaming drill bit 18, increase its service life, and soften the soil, thereby accelerating drilling efficiency. The presence of groundwater in the inner cavity 5 of the pipe pile can lubricate the long spiral drill rod 21 and the excavated soil to be removed in the inner cavity 5 of the pipe pile, increasing soil removal efficiency, improving soil removal effect, reducing soil removal resistance, and saving power costs.

[0078] Correspondingly, after the "pile-soil gap" 20 is formed and before grouting, a multi-functional vacuum pump 31 is used to change the inner cavity 5 of the pipe pile to a negative pressure state. Through the prefabricated permeable reinforced concrete structure 13 of the pile body, the groundwater in the "pile-soil gap" 20 and the surrounding soil 19 within a certain range is discharged into the inner cavity 5 of the pipe pile, causing the "pile-soil gap" 5 to be in a waterless environment for a short period of time. This greatly reduces the dilution effect of the groundwater in the "pile-soil gap" on the grouting fluid, ensuring the original physical and mechanical properties of the grouting fluid, thereby improving the grouting effect and the frictional resistance of the pile side. At the same time, after the groundwater is discharged into the inner cavity of the pipe pile, it is pumped out to the ground water storage tank 32 and the mixing tank 36, which can be used to prepare the grouting fluid 37, greatly saving water.

[0079] Next, after the grout in the "pile-soil gap" solidifies, the first permeable reinforced concrete structure 13-1, which is prefabricated with a variable diameter and a length equal to the wall thickness of the pipe pile, is replaced with a second permeable reinforced concrete structure 13-2, which has a variable diameter but a length several times the wall thickness of the pipe pile. The second permeable reinforced concrete structure 13-2 penetrates the soil around the pile 19 to a certain depth after passing through the pipe pile wall, which can greatly increase the side friction resistance of the pile foundation, thereby greatly improving the bearing capacity of the drilling and pipe-following drainage anti-buoyancy pile 1, especially the vertical pull-out bearing capacity of a single pile, and ultimately greatly improving the anti-buoyancy capacity of the pile foundation.

[0080] Finally, the second permeable reinforced concrete structure 13-2, which enters the soil around the pile 19 to a certain depth, can drain the groundwater in the soil around the pile 19 into the inner cavity 5 of the pipe pile. When pouring the pile foundation 39, several drainage pipes 27 are reserved in the inner cavity 5 of the pipe pile. Finally, the groundwater in the inner cavity 5 of the pipe pile can be continuously pumped to the ground water storage tank 32 for later use. This can achieve the purpose of lowering the groundwater level during the entire construction process, so as to realize the anti-buoyancy function of the underground structure.

[0081] The present invention has been further described above with reference to specific embodiments. However, it should be understood that the specific description herein should not be construed as limiting the nature and scope of the present invention. Various modifications made to the above embodiments by those skilled in the art after reading this specification are all within the scope of protection of the present invention.

Claims

1. A type of drilling-while-drilling drainage anti-buoyancy pile, characterized in that: The structure includes an anti-buoyancy pile, in which a through channel is opened in the middle of the anti-buoyancy pile along its length to form the inner cavity of the pipe pile; a steel mesh and a grouting pipe are installed inside the pipe wall of the anti-buoyancy pile; a number of drainage holes are formed on the pipe wall of the anti-buoyancy pile at intervals; and a permeable reinforced concrete structure is built into the drainage holes. A steel structure is provided on the inner wall of the drainage hole, and the steel structure at the drainage hole wall is fixedly connected to the steel mesh inside the pipe wall by steel bar connecting ribs. The drainage hole has a stepped cylindrical wall, including an inner wall and an outer wall. The inner wall is located near the inner cavity of the pipe pile, and the cross-sectional diameter of the inner wall is larger than that of the outer wall. The length of the inner wall is also greater than that of the outer wall. The permeable reinforced concrete structure includes a permeable reinforced concrete upper structure and a permeable reinforced concrete lower structure. When the diameter and length of the permeable reinforced concrete upper structure match the diameter and length of the inner hole wall, and the diameter and length of the permeable reinforced concrete lower structure match the diameter and length of the outer hole wall, a first permeable reinforced concrete structure is formed, thereby enabling the docking and installation of the first permeable reinforced concrete structure with the drainage hole. When the diameter and length of the permeable reinforced concrete upper structure match the diameter and length of the inner hole wall; and the diameter of the permeable reinforced concrete lower structure matches the diameter of the outer hole wall, and the length of the permeable reinforced concrete lower structure is greater than the length of the outer hole wall, a second permeable reinforced concrete structure is formed to achieve the docking installation of the second permeable reinforced concrete structure and the drainage hole.

2. The anti-buoyancy pile with drainage and casing as described in claim 1, characterized in that: A pile shoe is provided at the end of the anti-buoyancy pile.

3. A construction method for a drilling-while-drilling drainage anti-buoyancy pile, characterized in that: The application of the drilling-while-drilling drainage anti-buoyancy pile as described in claim 1 or 2 includes the following steps: S01: Fabrication of Drilling-while-conduit drainage anti-buoyancy piles: Based on the preliminary geological survey, determine the soil layer information and groundwater occurrence information, design the number and location of drainage holes for the drilling-while-conduit drainage anti-buoyancy piles, and fabricate the drilling-while-conduit drainage anti-buoyancy piles, as well as the first permeable reinforced concrete structure and the second permeable reinforced concrete structure installed in the drilling-while-conduit drainage anti-buoyancy piles according to actual needs. S02: Pile driving: After determining the pile position, insert the first permeable reinforced concrete structure into the drainage hole of the drilling and casing drainage anti-buoyancy pile, and lock the first permeable reinforced concrete structure. Subsequently, a drilling and casing pile driving machine was used to drive the drilling and casing drainage anti-buoyancy piles. The enlarged drill bit and the long spiral drill rod entered the soil layer through the inner cavity of the drilling and casing drainage anti-buoyancy pile to drill, so that there is a "pile-soil gap" between the drilling and casing drainage anti-buoyancy pile and the surrounding soil. After the reaming drill bit is drilled into the hole, the drilling-while-drilling drainage anti-buoyancy pile sinks synchronously with the reaming drill bit. When the first section of the drilling-while-drilling drainage anti-buoyancy pile sinks to the depth of the pile top from the ground that meets the design requirements, the first section of the drilling-while-drilling drainage anti-buoyancy pile is clamped with a pile clamping device to perform pile splicing and drill rod extension. At the same time, the grouting pipes on the pile sides of the upper and lower anti-buoyancy piles are connected, and then drilling continues until the reaming drill bit enters the interior of the medium and slightly weathered rock layer by more than 0.5m. S03: The pile end is sealed with fine stone concrete: After drilling to the design depth, the long spiral drill rod and the reaming drill bit are withdrawn from the inner cavity of the pipe pile. Then, the slag removal bucket is inserted into the pile end through the inner cavity of the pipe pile of the pipe-following drainage anti-buoyancy pile to remove the pile end sediment and pile end mud and water. Then, the steel guide pipe is lowered to near the bottom surface of the pile and fine stone concrete is poured. S04: Drive piles to moderately weathered rock strata: After the fine stone concrete is poured, the pile end of the drilling and casing drainage anti-buoyancy pile is pressed down by the drilling and casing pile machine, and the pile end of the drilling and casing drainage anti-buoyancy pile is pressed into the bottom of the hole, so that it is cemented into a whole with the moderately weathered rock strata under the action of the fine stone concrete. S05: Drainage of "pile-soil gap": During the process of filling the pile end with fine stone concrete to seal the bottom and driving the pile to the medium and slightly weathered rock layer, groundwater gradually gathers into the "pile-soil gap" and flows into the inner cavity of the pipe pile through the first permeable reinforced concrete structure set in the anti-buoyancy pile, and the water in the inner cavity of the pipe pile is discharged through the drainage pipe. S06: Grouting of the "pile-soil gap": After most of the water in the "pile-soil gap" has been drained, grouting is carried out on the pile side. At this time, except for retaining two drainage pipes, the entire drainage system is dismantled and moved to the next pile position for later use. According to the water-cement ratio designed for pile side grouting, the grouting liquid is prepared in the mixing tank. After the grouting liquid is mixed evenly, it is injected into the "pile-soil gap" through the grouting pump and the pile side grouting pipe pre-embedded in the pipe pile. S07: Replace the first permeable reinforced concrete structure with the second permeable reinforced concrete structure: After the grouting body on the pile side meets the strength requirements, remove the first permeable reinforced concrete structure and continue drilling into the soil through the drainage hole. Then, insert the second permeable reinforced concrete structure into the drainage hole and enter the soil. S08: Casting the pile cap and exerting anti-buoyancy capability: Subsequently, the pile cap is cast, the drainage pipe pre-reserved in the inner cavity of the pipe pile is cast into the pile cap, and a drainage outlet is reserved on the side wall of the pile cap.

4. The construction method of the drilling-while-drilling drainage anti-buoyancy pile according to claim 3, characterized in that: Throughout the construction of the foundation and superstructure, a multi-functional pump is used to apply negative pressure to the inner cavity of the pipe pile through the drainage outlet and drainage pipe. Under the action of negative pressure, groundwater flows into the inner cavity of the pipe pile through the second permeable reinforced concrete structure, and the groundwater in the inner cavity of the pipe pile is pumped out through the drainage pipe.

5. The construction method of the drilling-while-drilling drainage anti-buoyancy pile according to claim 3, characterized in that: If the groundwater is abundant and cannot be completely removed by natural drainage in step S05, then negative pressure treatment should be applied to the inner cavity of the pipe pile after step S05 is completed.

6. The construction method of the drilling-while-drilling drainage anti-buoyancy pile according to claim 5, characterized in that: A layer of rubber rings is laid on the end plate of the drilling and pipe-following drainage anti-buoyancy pile, and then the cover plate is fixed to the end plate to seal the inner cavity of the pipe pile. At this point, the vacuum pump is started, and the pressure value inside the pipe pile is monitored in real time by a pressure gauge to complete the negative pressure treatment of the pipe pile's inner cavity.

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