Construction method of anti-pulling bearing steel pipe pile

Abstract

Construction method of anti-pulling bearing steel pipe pile, which relates to the technical field of building anti-floating, includes the following steps: site leveling → pile position measurement and positioning → production and installation of steel pipes → pile body construction → drilling of anchorage end → removal of drill pipe and relocation of machine → installation of steel reinforcement cage and connecting plate → grouting or concrete pouring → anti-floating node at pile top → pile formation. The present invention significantly improves the anti-pulling capacity of the steel pipe pile, solves the problem of building floating and improves the bearing capacity of the building. It is safer, more durable and more reliable for the building. The construction quality of this method is visually controllable, changing the existing design and construction technology of anti-floating anchor rods and cables to resist building floating. It significantly saves construction cost and construction period.

Description

Technical Field

[0001] The invention relates to the technical field of anti-floating of buildings, and in particular to a construction method of anti-pullout bearing steel pipe piles. Background Art

[0002] In modern building design and construction, fluctuations in groundwater levels pose a significant threat to building stability. In particular, when groundwater levels rise, buildings are susceptible to buoyancy, causing structural damage and leading to serious economic losses and safety hazards. To prevent this, engineering measures such as anti-floating piles, anti-floating anchor rods, and anti-floating anchor cables are widely used. However, in practical application, these anti-floating measures still face numerous shortcomings and challenges.

[0003] At present, when dealing with the anti-floating problem in deep silt layers (20m to 60m), the existing anti-floating anchor rods and anti-floating anchor cables have the following problems:

[0004] 1. The verticality of drilling is difficult to guarantee: During the drilling process, due to complex geological conditions, the verticality is difficult to control, resulting in the inability to place steel bars and anchor cables to the designed depth, seriously affecting the anti-floating effect.

[0005] 2. Mud wall is prone to hole collapse: In strata with deep silt layers and abundant groundwater, the drilling mud wall is prone to hole collapse, which also makes it impossible for steel bars and anchor cables to reach the designed position, reducing the anti-floating performance.

[0006] 3. Insufficient rock penetration capability of drilling rigs: Ordinary drilling rigs lack sufficient penetration power in the rock layer, which makes it impossible for anti-floating anchor rods and anti-floating anchor cables to penetrate deep into the underground rock layer, further weakening the anti-floating capability.

[0007] 4. Insufficient anchoring of anchor rods and anchor cables: Existing anti-floating anchor rods and anti-floating anchor cables are often not designed to firmly anchor the ends of anchor rods and anchor cables to the underground rock formations. When the groundwater level rises, the building is easily floated due to buoyancy.

[0008] 5. The construction cost of the casing process is high: Although the casing process can solve the problems of hole collapse and rock penetration to a certain extent, its construction cost is significantly increased, which is not conducive to widespread application.

[0009] 6. Low construction efficiency: The existing construction methods of anti-floating anchor rods and anti-floating anchor cables are relatively cumbersome and inefficient, which seriously affects the progress of the project.

[0010] 7. Weak load-bearing capacity and pull-out resistance: Due to the aforementioned issues, existing anti-floating anchor rods and cables perform poorly in terms of load-bearing capacity and pull-out resistance, making them unable to meet the anti-floating requirements in complex geological conditions. There are numerous cases where buildings floated after construction, resulting in secondary anti-floating measures.

[0011] Therefore, anti-floating anchor rods and anti-floating cable anchors are difficult to meet the anti-floating requirements under complex geological conditions. Summary of the Invention

[0012] The object of the present invention is to provide a construction method for anti-pulling bearing steel pipe piles, which has better verticality, the pile diameter can reach: 168mm - 600mm, the drill can carry the steel pipe and penetrate into the moderately weathered or slightly weathered layer, significantly improving the single-pile bearing capacity. Drilling is carried out again at the bottom of the pipe pile and a small steel reinforcement cage is placed to pour cement slurry and concrete for rock socketing and anchoring. The enlarged end of the anchored steel pipe increases the anti-pulling ability of the steel pipe pile, the integrity of the pile body is good, and at the same time, it has sufficient bearing capacity. The steel pipe pile connecting steel collar increases the stiffness of the pile body against lateral displacement. Since the penetration into the rock layer strengthens the anti-pulling ability and bearing capacity of the single pile, the total project cost and construction period can be significantly saved.

[0013] To solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0014] A construction method for anti-pulling bearing steel pipe piles, comprising the following steps: [[ID=—>12]] [[ID=—>13]]

[0015] [[ID=—>14]]Step S1. Site leveling; [[ID=—>15]] [[ID=—>16]]

[0016] [[ID=—>17]]Step S2. Pile position measurement and positioning; [[ID=—>18]] [[ID=—>19]]

[0017] [[ID=—>20]]Step S3. Fabrication and installation of the steel pipe; [[ID=—>21]] [[ID=—>22]]

[0018] [[ID=—>23]]Step S4. Pile body construction; [[ID=—>24]] [[ID=—>25]]

[0019] [[ID=—>26]]Step S5. Boring of the anchoring end; [[ID=—>27]] [[ID=—>28]]

[0020] [[ID=—>29]]After the drilling in Step S6 is completed, remove the drill rod and move the machine; [[ID=—>30]] [[ID=—>31]]

[0021] [[ID=—>32]]Step S7. Install the steel reinforcement cage and connecting plate; [[ID=—>33]] [[ID=—>34]]

[0022] [[ID=—>35]]Step S8. Pour cement slurry or concrete; [[ID=—>36]] [[ID=—>37]]

[0023] [[ID=—>38]]Step S9. Anti-floating connection at the pile top; [[ID=—>39]] [[ID=—>40]]

[0024] [[ID=—>41]]Step S10. Pile formation. [[ID=—>42]] [[ID=—>43]]

[0025] [[ID=—>44]]Furthermore, in Step S3, a stepped retaining ring is welded to the bottom end of the steel pipe. The outer diameter of the upper half of the stepped retaining ring is smaller than the inner diameter of the steel pipe, and the outer diameter of the lower half of the stepped retaining ring is the same as the outer diameter of the steel pipe. After the stepped retaining ring is welded and fixed to the steel pipe, several steel sheets are used for reinforcement welding to improve the anti-pulling ability of the stepped retaining ring. [[ID=—>45]] [[ID=—>46]]

[0026] Further, in step S3, the upper and lower sections of steel pipes are connected by casing pipes or hoop fasteners. When connecting, first weld the casing pipe or hoop fastener to one end of the steel pipe in advance. During construction, insert the upper steel pipe into the outer casing pipe or hoop fastener of the lower steel pipe, and then carry out welding. The connection between the steel pipes in the rock stratum is butt-welded.

[0027] Further, in step S4, the pile body construction uses the casing drilling method to form a hole. The hole is formed starting from the ground where the original concrete surface layer is broken. Bore downward with the original ground as ±0.00m. The drill pipe operates inside the steel pipe. The bottom of the drill pipe is connected to a hammer, and an eccentric bit is connected below the hammer. The tail of the bit is stuck on the retaining ring. During operation, the bit rotates and strikes downward against the retaining ring while drilling. The retaining ring is welded to the pile body and can also pull the steel pipe pile downward; during hole formation, due to the huge air pressure, water, soil, silt, sand, and rock cuttings in the formation are flushed out of the ground surface. The steel pipe successively penetrates through the soil layer, silt layer, sand layer, and at the same time enters the rock for 2 meters or more, then stops operation. After the hole is formed, there is no mud in the steel pipe pile, and only clear water at the bottom.

[0028] Further, in step S5, during the hole formation process of the anchoring end, use a drill bit one size smaller to re-drill into the rock for 4 meters or more. After the hole is formed, there is no mud in the steel pipe pile and the rock-in section, and only clear water at the bottom.

[0029] Further, in step S7, the steel reinforcement cage and the connecting plate are assembled on the ground and hoisted from the ground to the bottom of the steel pipe pile. The connecting plate is stuck on the retaining ring at the bottom of the steel pipe. A grouting hole is left in the middle of the connecting plate as a channel for subsequent grouting.

[0030] Further, in step S8, after the cement slurry or concrete is poured and cured, the end of the steel pipe pile can be firmly anchored in the underground rock stratum. Use 42.5R ordinary Portland cement to prepare pure cement slurry with a water-cement ratio of 0.5. It is required that the cube compressive strength of the pile body cement is not less than 30MPa. Use one-time grouting with a grouting pressure of 2.5MPa; after the grouting pipe reaches the bottom of the hole, lift it by 50mm, and use a high-pressure grouting pump to insert the conduit to start grouting from the bottom of the hole until pure slurry emerges from the hole mouth.

[0031] Further, in step S9, the connection between the steel pipe and the bearing platform or the basement floor slab is made by steel bars. 8 C20 steel bars are evenly distributed along the circumference of the pile, and the anchoring length of the steel bars at the pile head is not less than 70cm.

[0032] Furthermore, in step S4, the eccentric drill bit is in a drilling state during the hole forming process, and is in a retracted state when the drill bit is extracted after the hole forming is completed; during the hole forming period, the water, soil, sand, silt, and rock debris in the stratum are flushed out of the surface due to the huge air pressure, and the drilling rig is closed with a curtain around it; the impactor impacts the drill bit and hits the retaining ring to drive the steel pipe pile and the pipe to drill into the pile; when the hole is formed, the rock debris at the hole mouth is cleaned manually in time to prevent the rock debris from entering the hole for the second time, causing accumulation and repeated breakage at the hole mouth, and preventing the occurrence of buried drill.

[0033] Furthermore, in step S3, when welding the steel pipe extension, welding should be performed symmetrically along both sides at the same time, and the weld quality should meet the relevant requirements for steel structure acceptance; in order to ensure construction quality and progress, welding wire is used for steel pipe welding.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] The present invention discloses a method for constructing pull-out bearing steel pipe piles. The anti-floating steel pipe piles are a new type of micro-pile foundation used to enhance the bearing capacity of the foundation, the resistance of buildings to groundwater buoyancy and resistance to lateral damage. They are particularly suitable for areas with high groundwater levels or low deep silt bearing capacity. The steel pipe is driven through the soil layer, sand layer, and silt and into the rock layer by about 2 meters. A smaller drill bit is then used to drill into the rock a second time to a depth of 4 meters or more. After the hole is formed, there is no mud in the steel pipe pile and in the rock section, and there is only clear water at the bottom. A small steel cage is made, and the made steel cage is placed at the bottom of the steel pipe pile and drilled into the rock a second time to a depth of 4 meters or more. A guide tube is placed and cement slurry, grouting material or self-flowing dense concrete is injected. A small steel cage is placed at the bottom of the pipe pile, and the pile is drilled into the rock a second time to a depth of 4 meters or more. After solidification, the steel pipe pile can be effectively anchored to the underground rock layer. The pull-out resistance of the steel pipe pile is significantly improved, solving the problem of building floating and improving the bearing capacity of the building. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0037] Figure 1 This is a process flow chart of a construction method for pull-out bearing steel pipe piles according to an embodiment of the present invention;

[0038] Figure 2 This is a schematic diagram of the construction of a steel pipe body according to an embodiment of the present invention;

[0039] Figure 3 2. It is a schematic diagram of the hole forming at the bottom anchoring end of the anti-floating steel pipe pile according to an embodiment of the present invention;

[0040] Figure 4 Schematic diagram of installing the steel reinforcement cage and connecting plate in the embodiment of the present invention;

[0041] Figure 5 Schematic diagram of lowering the conduit into the pile in the embodiment of the present invention;

[0042] Figure 6 Schematic diagram of the construction of injecting cement slurry and concrete into the pile in the embodiment of the present invention;

[0043] Figure 7 Schematic diagram of the anti - floating steel pipe pile in the embodiment of the present invention;

[0044] Figure 8 Schematic diagram of the anti - floating node at the top of the pile in the embodiment of the present invention;

[0045] Figure 9 Schematic diagram of the enlarged joint of the pile in the embodiment of the present invention;

[0046] Figure 10 Schematic diagram of the enlarged connecting plate in the embodiment of the present invention;

[0047] Figure 11 Schematic diagram of the enlarged steel reinforcement cage in the embodiment of the present invention;

[0048] Figure 12 Schematic diagram of the enlarged retaining ring in the embodiment of the present invention. Detailed implementation manners

[0049] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0050] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "upper", "lower", "front", "rear", "vertical", "horizontal", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings. It is 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 thus should not be construed as a limitation to the present invention.

[0051] In the present invention, unless otherwise clearly defined and limited, terms such as "installation", "connection", "linkage", "fixation" shall be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal communication of two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0052] In the present invention, unless otherwise clearly defined and limited, the first feature being "on" or "under" the second feature may be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may be that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "beneath" and "underneath" the second feature may be that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature has a lower horizontal height than the second feature.

[0053] As Figures 1-12 shown, the present invention provides a construction method for anti-pulling bearing steel pipe piles, and its construction steps are as follows:

[0054] Referring to Figure 1 , leveling the site → measuring and positioning the pile position → manufacturing and installing the steel pipe → pile body construction → drilling the anchoring end → removing the drill pipe and moving the machine → installing the steel reinforcement cage and connecting plate → grouting or pouring concrete → anti-floating node at the pile top → forming the pile.

[0055] Referring to Figures 1 to 8 , the specific construction method is as follows:

[0056] I. Site leveling

[0057] The construction of the anti-pulling bearing steel pipe pile starts from the hole-forming operation at the elevation of (±0.000). Before the formal start of construction, the primary task is to level the site to ensure the suitability of the construction environment. This step includes thoroughly removing all obstacles on the surface and underground in the pile position area to clear the way for subsequent construction. For the low-lying areas in the site, cohesive soil is used for backfilling and compaction to construct a stable and flat working plane. Ensure that the construction machine can move smoothly on the ground, thus guaranteeing the construction efficiency and quality.

[0058] If the site conditions fail to meet the above standards, steel plates can be laid as appropriate to further strengthen the bearing capacity of the ground. At the same time, for the operation position, more meticulous ramming and leveling treatments are carried out to ensure that its compactness meets the requirements. Prevent the drilling rig from uneven settlement during operation, and thus effectively avoid the problem of hole deviation, laying a solid foundation for the high-quality construction of the anti-pull bearing steel pipe piles.

[0059] II. Pile position measurement and positioning

[0060] 1. Preparation for construction layout: After the construction site is adjusted and leveled, the construction layout work is carried out immediately. Before layout, it is necessary to rigorously review the fixed level points specifically set for this project within the construction site to ensure their accuracy. The measurement points need to be carefully protected and regularly inspected to prevent the points from being damaged or the accuracy from being reduced due to other factors, ensuring the reliability of the measurement data.

[0061] 2. Pile position layout technology: The layout work of the pile position is carried out using a total station and precisely operated in combination with the actual structure on site. The measuring instruments used need to be effectively calibrated by a qualified inspection unit and used within their effective service life. In order to strictly comply with the measurement requirements and minimize measurement errors or avoid mistakes at the same time, the "double measurement system" will be implemented during the measurement process, that is, two independent measurements to ensure the accuracy of the results.

[0062] 3. Level point setting and elevation control: Several level points are set near the construction area, and these level points are all outside the influence range of the pile driving operation to ensure that the pile top elevation can be accurately controlled. Immediately after the construction of each pile is completed, the elevation record is made, providing key data for the subsequent project quality control.

[0063] 4. Setting of safety permanent control points: Based on the original confirmed coordinate points, the pile positions are accurately measured and laid out. At the same time, two safety permanent control points are measured and set in the area not affected by the pile driving operation. These control points will be used to check and correct each axis point or review the pile position during the construction process to ensure the construction accuracy. The surveying of the construction axis must be carried out strictly according to the design coordinate points and confirmed correct after multiple reviews. The position of the axis control points on the construction site should be set away from the pile driving operation area and protective measures should be taken to ensure its stability and reliability.

[0064] 5. Pile position numbering and laying: According to the designed pile layout drawing, each pile is numbered one by one according to the construction sequence. Then, according to the axis corresponding to the pile number, the pile position is accurately laid out according to the dimension requirements. This step ensures the accuracy of the pile position and provides strong support for the subsequent pile driving operation.

[0065] III. Fabrication and installation of Steel Pipe 1

[0066] 1. Manufacturing and installation process of steel pipe 1: The steel pipe material is carefully selected as Q355B or other high-quality steel according to design requirements. Taking the steel pipe with a diameter of DN219 as an example, the wall thickness is set to 8mm. At the end of the steel pipe (i.e., the bottom of the pile), a stepped retaining ring 3 is specially designed and welded. This retaining ring has a unique structure. The outer diameter of the upper half is slightly smaller than the inner diameter of the steel pipe pile, while the outer diameter of the lower half is the same as the outer diameter of the steel pipe pile. During installation, first place the retaining ring accurately inside the steel pipe, and then perform circumferential welding to ensure a firm connection. To further improve the anti-pulling performance of the retaining ring, after welding is completed, more than 4 steel sheets with a size of 60mm wide × 80mm long × 6mm thick are additionally used to reinforce the welding between the retaining ring and the steel pipe, forming a more stable structure and improving the anti-pulling ability.

[0067] The connection method between the upper and lower sections of the steel pipe adopts a casing 2 or a hoop, and their heights are both 200mm. During the prefabrication stage, first weld the casing or hoop to one end of the steel pipe. During construction, accurately insert the upper steel pipe into the outer casing or hoop of the lower steel pipe, and then perform fine welding to ensure the strength and stability of the connection. In particular, for steel pipes constructed in rock formations, the connection method adopts butt welding to adapt to more complex geological conditions.

[0068] 2. Construction site segmented operation strategy: The construction site is divided into indoor and outdoor operation areas according to spatial conditions. Due to the limited indoor height, the steel pipe is divided into 2m-long sections for operation; while in the outdoor operation area, 6m-long steel pipe sections are used. The connection between the upper and lower sections of the steel pipe also adopts the casing method. During prefabrication, a 200mm-high casing is welded in advance to one end of the steel pipe. During construction, accurately insert the upper steel pipe into the outer casing of the lower steel pipe and perform fine welding to ensure the firmness and stability of the connection.

[0069] 3. Construction by the pipe-following drilling method: This project innovatively adopts the pipe-following drilling method. In this method, while the hole is being formed, the steel pipe can follow synchronously, greatly improving the construction efficiency and hole-forming quality.

[0070] 4. Quality control of steel pipe splicing welding: During the steel pipe splicing welding process, the method of symmetrically welding simultaneously along both sides is adopted to ensure the uniform distribution of welding stress. The weld quality strictly complies with the relevant standards for steel structure acceptance to ensure that the strength and tightness of the welded joint meet the design requirements.

[0071] 5. Application of high-efficiency welding technology: To ensure construction quality and progress, the wire welding technology is selected. This technology has the advantages of fast welding speed, high weld quality, and simple operation, and can significantly improve the efficiency and quality of steel pipe welding, providing a strong guarantee for the successful completion of the project.

[0072] IV. Pile body construction

[0073] The advanced pipe - following drilling technology is adopted for hole formation operations. The whole process starts with the removal of the original concrete surface layer, and then, taking the original ground surface as the reference point (±0.00m), the tunneling operation is carried out downward. Taking the steel pipe with a diameter of 219mm as an example, under the specific conditions of pipe - following drilling, the selected down - the - hole drill is equipped with an eccentric bit, and its maximum hole - forming diameter can reach 237mm, fully meeting the construction requirements.

[0074] During the operation process, the drill pipe conducts precise operations inside the steel pipe. At its bottom, it is tightly connected to a 6 - inch impactor, and further below the impactor is connected to a 219mm eccentric bit. This enables the tail of the bit to be firmly stuck on the retaining ring. Thus, during the operation, while the bit rotates, it can forcefully strike and drill downward against the retaining ring. The retaining ring and the pile body are connected together through a precise welding process. This design not only enhances the structural stability but also can effectively bring the steel pipe pile into the ground along with the drilling process of the bit.

[0075] During hole formation, a huge air pressure plays a crucial role. It can effectively flush out impurities such as water, soil, silt, sand, and rock cuttings in the formation to the ground surface, thereby achieving the penetration of the rock layer. This efficient hole - forming process ensures that there is no residual mud inside the steel pipe pile after hole formation, and only clear water remains at the bottom.

[0076] V. Hole formation of the anchorage end

[0077] Then, use a drill bit one size smaller to drill into the rock again for 4 meters or more. This section is the anchorage section of the anti - floating pile and the rock layer. After hole formation, there is no mud in the steel pipe pile and the rock - entering section, and only clear water remains at the bottom.

[0078] VI. Removing the drill pipe and moving the machine

[0079] Remove the drill pipe and move the machine; after the drilling is completed, remove the drill pipe and drilling tools in sequence, and move the machine to the next pile position. At the same time, cover the pile top with a pile cap to prevent sediment from flowing in.

[0080] VII. Installing the steel reinforcement cage and connecting plate

[0081] Install the steel reinforcement cage 4 and the connecting plate 5; the steel reinforcement cage and the connecting plate are assembled on the ground and hoisted from the ground to the bottom of the steel pipe pile. The connecting plate is stuck on the retaining ring at the bottom of the steel pipe. A hole is left in the middle of the connecting plate as the channel for subsequent grouting.

[0082] VIII. Grouting cement slurry or concrete

[0083] Grouting; Prepare pure cement slurry with 42.5R ordinary Portland cement; Use the drilling rig and mud pump to grout from bottom to top until pure cement slurry emerges from the ground hole orifice; The grouting in the pile hole uses pure cement slurry, the cement strength grade is M30, the water-cement ratio is 0.5, and it is required that the cube compressive strength of the pile body cement is not less than 30 MPa; Adopt one-time grouting, and the grouting pressure is 2.5 MPa; After the grouting pipe reaches the bottom of the hole, lift it by 50 mm, use the high-pressure grouting pump, insert the conduit and start grouting from the bottom of the hole until pure slurry emerges from the hole orifice

[0084] 1) Prepare M30 pure cement slurry with 42.5R ordinary Portland cement according to the water-cement ratio of 0.5

[0085] 2) The grouting in the pile hole uses pure cement slurry, the cement strength grade is M30, the water-cement ratio is 0.5, and it is required that the cube compressive strength of the pile body cement is not less than 30 MPa

[0086] 3) Adopt one-time grouting, and the grouting pressure is 2.5 MPa

[0087] 4) Use the high-pressure grouting pump, insert the conduit 6 and start grouting from the bottom of the hole until pure slurry emerges from the hole orifice

[0088] Alternatively, underwater self-compacting concrete can be poured with the conduit to replace the above method of grouting cement slurry. The pouring sequence is from bottom to top, and the conduit is pulled out while pouring

[0089] IX. Anti-floating joint at the pile top

[0090] For the anti-floating connection at the pile top, the connection between the steel pipe and the bearing platform and the basement floor slab uses steel bar connection. 8 C20 steel bars 7 are evenly distributed along the circumference of the pile, and the anchorage length of the steel bars in the pile head is not less than 70 cm

[0091] The present invention discloses a construction method for anti-pulling bearing steel pipe piles. The anti-floating steel pipe piles are a new type of micro pile foundation used to enhance the bearing capacity of the foundation, the anti-groundwater buoyancy of buildings, and the anti-lateral damage. It is particularly suitable for areas with a relatively high groundwater level or low bearing capacity of deep silt. The steel pipe is passed through soil layers, sand layers, and silt and driven into the rock layer about 2 meters, and then a drill bit one size smaller is used for secondary drilling into the rock for 4 meters or more (the depth is determined according to the anti-pulling requirements). After the hole is formed, there is no mud in the steel pipe pile and the rock-injecting section, and only clear water at the bottom. A small steel reinforcement cage is fabricated and placed at the bottom of the steel pipe pile at a depth of 4 meters or more after secondary drilling into the rock. A conduit is placed, and cement slurry, grouting material, or self-leveling dense concrete is injected. When the small steel reinforcement cage is placed at a depth of 4 meters or more in the rock after secondary entry at the bottom of the pipe pile and solidifies, the steel pipe pile can be effectively anchored to the underground rock layer. This significantly improves the anti-pulling capacity of the steel pipe pile, solves the problem of building floating, and improves the bearing capacity of the building (anti-floating anchor rods and cables cannot improve the bearing capacity of the building). It is more reliable for the safety and durability of the building. The construction quality of this method is visually controllable, changing the existing design and construction technology of anti-floating anchor rods and cables for resisting building floating. It significantly saves construction costs and construction period.

[0092] The construction quality of the construction method for anti-pulling bearing steel pipe piles is visually controllable, changing the existing design and construction technology of anti-floating anchor rods and cables (the situation of easy failure caused by uncontrollable forming quality such as mud wall protection of anchor rods and cables, collapse of deep silt holes, and verticality). The construction method for anti-pulling bearing steel pipe piles can significantly reduce construction costs and construction period, and at the same time improve the anti-floating capacity and bearing capacity of the building, significantly improving the safety, durability, and reliability of the building.

[0093] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0094] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. Construction method of anti-pulling bearing steel pipe pile, characterized in that, It includes the following steps: Step S1. Site leveling; Step S2. Pile position measurement and positioning; Step S3. Fabrication and installation of steel pipe (1); Step S4. Pile body construction; Step S5. Boring of the anchoring end; Step S6. After the boring is completed, remove the drill pipe and move the machine; Step S7. Install the steel reinforcement cage (4) and the connecting plate (5); Step S8. Pour cement slurry or concrete; Step S9. Anti-floating connection at the pile top; Step S10. Pile formation; In Step S3, a stepped retaining ring (3) is welded to the bottom end of the steel pipe (1). For the stepped retaining ring (3), the outer diameter of the upper half is smaller than the inner diameter of the steel pipe (1), and the outer diameter of the lower half is the same as the outer diameter of the steel pipe (1). After the stepped retaining ring (3) is welded and fixed to the steel pipe (1), several steel sheets (31) are used for reinforcement welding to improve the anti-pulling capacity of the stepped retaining ring (3); In Step S4, the pile body construction is carried out by drilling with a casing pipe. The hole is formed starting from the ground where the original concrete surface layer is broken. Drilling is carried out downward with the original ground as ±0.00m. The drill pipe operates inside the steel pipe. The bottom of the drill pipe is connected to a hammer, and an eccentric bit is connected below the hammer. The tail of the bit is stuck on the retaining ring. During operation, while the bit rotates, it strikes against the retaining ring and drills downward. The retaining ring is welded to the pile body and can also pull the steel pipe pile downward at the same time. During the hole formation, due to the huge air pressure, water, soil, silt, sand, and rock cuttings in the formation are flushed out to the surface. The steel pipe sequentially penetrates through the soil layer, silt layer, sand layer, and at the same time enters the rock for 2 meters or more, then stops the operation. After the hole is formed, there is no mud in the steel pipe pile, and only clear water at the bottom; In Step S5, during the boring of the anchoring end, a drill bit of a smaller size is used for secondary re-drilling into the rock for 4 meters or more. After the hole is formed, there is no mud in the steel pipe pile and the rock-in section, and only clear water at the bottom; In Step S7, the steel reinforcement cage (4) and the connecting plate (5) are assembled on the ground and hoisted from the ground to the bottom of the steel pipe pile. The connecting plate is stuck on the retaining ring at the bottom of the steel pipe. A grouting hole (51) is left in the middle of the connecting plate as a channel for subsequent grouting.

2. The construction method of the anti-pulling bearing steel pipe pile according to claim 1, characterized in that, In Step S3, the upper and lower sections of the steel pipe (1) are connected by a casing pipe or a hoop. When connecting, first weld the casing pipe or hoop to one end of the steel pipe in advance. During construction, insert the upper steel pipe into the outer casing pipe or hoop of the lower steel pipe, and then carry out welding. The connection between the steel pipes in the rock layer is carried out by butt welding.

3. The construction method of the uplift-bearing steel pipe pile according to claim 1, characterized in that In Step S8, after the poured cement slurry or concrete solidifies, the end of the steel pipe pile can be firmly anchored in the underground rock layer. Pure cement slurry is prepared with 42.5R ordinary Portland cement, and the water-cement ratio is 0.

5. It is required that the cube compressive strength of the pile body cement is not less than 30MPa. One-time grouting is adopted, and the grouting pressure is 2.5MPa. After the grouting pipe reaches the bottom of the hole, it is lifted by 50mm. Using a high-pressure grouting pump, the conduit (6) is inserted and grouting starts from the bottom of the hole until pure slurry emerges from the hole mouth.

4. The construction method of the uplift bearing steel pipe pile according to claim 1, characterized in that, In Step S9, the connection between the steel pipe and the bearing platform or the basement floor is carried out by steel bars. 8 C20 steel bars (7) are evenly distributed along the circumference of the pile. The anchoring length of the steel bars at the pile head is not less than 70cm.

5. The construction method of the anti-pulling bearing steel pipe pile according to claim 1, characterized in that, In the step S4, during the hole-forming process, the eccentric drill bit is in the drilling state, and in the state of retracting when the drill bit is extracted after the hole-forming is completed; during the hole-forming, due to the huge air pressure, water, soil, sand, silt, and cuttings in the formation are flushed out to the surface, and the periphery of the drilling rig is enclosed by a cloth curtain; the purpose is to drive the steel pipe pile to follow the pipe and drill into a pile by the impactor impacting the drill bit and hitting the retaining ring; during the hole-forming, the artificial should clean the rock slag at the hole opening in time to prevent the rock slag from entering the hole again, causing the accumulation at the hole opening and repeated crushing, and preventing the occurrence of the phenomenon of drill string sticking.

6. The construction method of the anti-pulling bearing steel pipe pile according to claim 2, characterized in that, In the step S3, when the steel pipes are joined and welded, the welding should be carried out symmetrically and simultaneously along both sides, and the weld quality should meet the relevant requirements of the steel structure acceptance; to ensure the construction quality and construction progress, the steel pipes are welded by using welding wires.

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