Construction method of uplift bearing steel pipe pile

Abstract

A construction method of an anti-pulling bearing steel pipe pile relates to the technical field of building anti-floating, and comprises the following steps: leveling a site, measuring and positioning a pile position, manufacturing and mounting a steel pipe, constructing a pile body, drilling at an anchoring end, unloading a drill rod and moving a machine, mounting a reinforcement cage and a connecting plate, pouring cement paste or concrete, forming an anti-floating node at the top of the pile, and forming the pile. The anti-pulling capacity of the steel pipe pile is remarkably improved, the problem that a building floats upwards is solved, and the bearing capacity of the building is improved. And the safety and durability of the building are more reliable. According to the method, the construction quality is visual and controllable, and the design and construction technology that existing anti-floating anchor rods and anchor cables resist building floating are changed. And the construction cost and the construction period are obviously saved.

Description

Technical Field

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

[0002] In modern building design and construction, changes in groundwater levels pose a major threat to building stability. In particular, when groundwater levels rise, buildings are prone to float due to buoyancy, causing damage to the structure, leading to serious economic losses and safety hazards. To prevent this phenomenon, engineering measures such as anti-floating piles, anti-floating anchors and anti-floating anchor cables are widely used. However, in practical applications, these anti-floating measures still have many 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 ensure: 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. The 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, making 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 the ends of anchor rods and cables: The existing anti-floating anchor rods and cables are often not designed to firmly anchor the ends of the anchor rods and cables to the underground rock formations. When the groundwater level rises, the building is prone to float 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 complicated and inefficient, which seriously affects the progress of the project.

[0010] 7. Weak bearing capacity and pull-out resistance: Due to the above problems, the existing anti-floating anchor rods and anti-floating cables have poor bearing capacity and pull-out resistance, and it is difficult to meet the anti-floating requirements under complex geological conditions. There are many examples of buildings floating after construction, resulting in secondary anti-floating.

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

[0012] The purpose of the present invention is to provide a pull-out resistant load-bearing steel pipe pile construction method, which has better verticality and a pile diameter of 168mm-600mm. The drill rig can bring in the steel pipe and penetrate into the medium-weathered or slightly-weathered layer, significantly improving the bearing capacity of a single pile. Drill holes at the bottom of the pipe pile for the second time and place a small steel cage to pour cement slurry and concrete for rock-embedded anchoring. The anchored steel pipe end increases the pull-out resistance of the steel pipe pile, and the pile body has good integrity and sufficient bearing capacity. The steel pipe pile is connected to the steel hoop to increase the stiffness of the pile body for lateral displacement. The pull-out resistance and bearing capacity of the single pile are enhanced by penetrating into the rock layer, which can significantly save the total project cost and construction period.

[0013] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0014] The construction method of the pull-out bearing steel pipe pile comprises the following steps:

[0015] Step S1. Leveling the site;

[0016] Step S2. Pile position measurement and positioning;

[0017] Step S3. Production and installation of steel pipes;

[0018] Step S4. Pile construction;

[0019] Step S5. Forming a hole at the anchoring end;

[0020] Step S6. After the drilling is completed, remove the drill rod and move the machine;

[0021] Step S7. Install the steel cage and the connecting plate;

[0022] Step S8. pouring cement slurry or concrete;

[0023] Step S9. Pile top anti-floating connection;

[0024] Step S10: Piling.

[0025] Furthermore, in step S3, a step retaining ring is welded to the bottom end of the steel pipe, wherein the outer diameter of the upper half of the step retaining ring is smaller than the inner diameter of the steel pipe, and the outer diameter of the lower half of the step retaining ring is the same as the outer diameter of the steel pipe. After the step retaining ring is welded and fixed to the steel pipe, several steel sheets are used for reinforcement welding to improve the pull-out resistance of the step retaining ring.

[0026] Furthermore, in step S3, the upper and lower sections of the steel pipe are connected by a casing or a clamp. When connecting, the casing or the clamp is first welded to one end of the steel pipe in advance. During construction, the upper steel pipe is inserted into the outer casing or the clamp of the lower steel pipe, and then welded. The connection between the steel pipes in the rock formation is butt welding.

[0027] Furthermore, in step S4, the pile body is constructed by drilling with a pipe, and the hole is formed from the ground after the original concrete surface layer is broken. The hole is excavated downward with the original ground as ±0.00m. The drill rod operates in the steel pipe, and the bottom of the drill rod is connected to an impactor, and an eccentric drill bit is connected below the impactor. The tail of the drill bit is stuck on the retaining ring. During operation, the drill bit rotates and hits the retaining ring while drilling downward. The retaining ring and the pile body are welded together, and at the same time, the steel pipe pile can be brought down downward; during the hole forming period, the water, soil, silt, sand, and rock debris in the stratum are flushed out of the ground due to the huge air pressure. The steel pipe successively passes through the soil layer, silt layer, sand layer, and at the same time, the rock is entered to 2 meters or more, and the operation is stopped. After the hole is formed, there is no mud in the steel pipe pile, and there is only clean water at the bottom.

[0028] Furthermore, in step S5, the anchor end hole forming process uses a smaller model drill bit to drill into the rock for 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 the rock section, and there is only clear water at the bottom.

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

[0030] Furthermore, 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 formation. Pure cement slurry is prepared with 42.5R ordinary Portland cement, and the water-cement ratio is 0.5. The compressive strength of the pile body cement cube is required to be not less than 30MPa. One-time grouting is adopted, and the grouting pressure is 2.5MPa. After the grouting pipe is lowered to the bottom of the hole, it is lifted up 50mm, and a high-pressure grouting pump is used. The catheter is inserted to start grouting from the bottom of the hole until pure slurry emerges from the hole mouth.

[0031] Furthermore, in step S9, the connection between the steel pipe and the cap or the basement floor is made by steel bars, 8 C20 steel bars are evenly distributed around the pile, and the length of the steel bar anchoring the pile head is not less than 70 cm.

[0032] Furthermore, in step S4, the eccentric drill bit is in a drilling state during the drilling process, and is in a retracted state when the drill bit is extracted after the drilling is completed; during the drilling process, 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 curtains around; the impactor impacts the drill bit and hits the retaining ring to drive the steel pipe pile and the pipe to drill into piles; when drilling, the rock debris at the hole mouth is cleaned manually and 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 the 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 invention discloses a method for constructing a pull-out bearing steel pipe pile. The anti-floating steel pipe pile is a new type of micro-pile foundation for enhancing the bearing capacity of the foundation, the resistance of the building to the buoyancy of groundwater and the resistance to lateral damage. It is particularly suitable for areas with high groundwater levels or low bearing capacity of deep silt. The steel pipe is passed through the soil layer, sand layer, and silt and driven into the rock layer for about 2 meters. Then a smaller drill bit is used to drill into the rock for a second time at a depth of 4 meters or more. After the hole is formed, there is no mud in the steel pipe pile and 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 for a second time at a depth of 4 meters or more. A conduit is placed, and cement slurry, grouting material or self-flowing compacting concrete is injected. A small steel cage is placed at the bottom of the pipe pile at 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, the problem of building floating is solved, and the bearing capacity of the building is improved. 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 drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. 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 creative labor.

[0037] Figure 1 This is a process flow chart of a construction method for anti-pulling load-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 Schematic diagram of hole formation at the bottom anchoring end of an anti-floating steel pipe pile according to an embodiment of the present invention;

[0040] Figure 4 It is a schematic diagram of installing a steel cage and a connecting plate according to an embodiment of the present invention;

[0041] Figure 5 Schematic diagram of the lower pipe in the pile according to the embodiment of the present invention;

[0042] Figure 6 This is a schematic diagram of the construction of cement slurry and concrete injection in piles according to an embodiment of the present invention;

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

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

[0045] Fig. 9 This is a schematic diagram of a pile connection sample according to an embodiment of the present invention;

[0046] Fig.10 This is a schematic diagram of a connecting plate according to an embodiment of the present invention;

[0047] Fig.11 2. It is a schematic diagram of a steel cage sample according to an embodiment of the present invention;

[0048] Fig.12 It is a schematic diagram of a retaining ring according to an embodiment of the present invention. DETAILED DESCRIPTION

[0049] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0050] In the description of the present invention, it is necessary to understand that the terms "upper", "lower", "front", "back", "vertical", "horizontal", "inside", "outside", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0051] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, 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 specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

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

[0054] Reference Figure 1 , level the site → measure and locate the pile position → make and install the steel pipe → construct the pile body → drill the anchor end → remove the drill rod and move the machine → install the steel cage and connecting plate → pour cement slurry or concrete → anti-floating node on the pile top → pile formation.

[0055] Reference Figures 1 to 8 , the specific construction method is:

[0056] 1. Site leveling

[0057] The construction of the pull-out bearing steel pipe piles begins with the drilling operation at the elevation of (±0.000). Before the construction officially starts, the first task is to level the site to ensure the suitability of the construction environment. This step includes completely removing all obstacles on the surface and underground in the pile area to clear the way for subsequent construction. For the low-lying areas on the site, clay soil is backfilled and compacted to build a stable and flat working surface. This ensures that the construction machines can move steadily and smoothly on the ground, thereby ensuring 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, more detailed compaction and leveling treatment should be carried out on the working position to ensure that its density meets the requirements. This prevents the drilling rig from sinking unevenly during the operation, thereby effectively avoiding the problem of hole deviation and laying a solid foundation for the high-quality construction of pull-out bearing steel pipe piles.

[0059] 2. Pile Position Measurement and Positioning

[0060] 1. Construction staking preparation: After the construction site is adjusted and leveled, the construction staking work will be carried out immediately. Before staking, it is necessary to strictly review the fixed leveling points specially set up for this project in the construction site to ensure their accuracy. The measurement points must be carefully protected and regularly inspected to prevent damage to the points or reduction in accuracy due to other factors, so as to ensure the reliability of the measurement data.

[0061] 2. Pile position setting technology: The pile position setting work uses a total station and is accurately operated in combination with the actual structure on site. The measuring instruments used must 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, the measurement process will implement a "double measurement system", 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, which are all outside the influence range of the piling operation to ensure that the pile top elevation can be accurately controlled. After each pile is completed, the elevation will be recorded immediately to provide key data for subsequent project quality control.

[0063] 4. Setting of safe permanent control points: Based on the original confirmed coordinate points, the pile position was accurately measured and placed. At the same time, we measured and set two safe permanent control points in the area not affected by the piling operation. These control points will be used to check and correct each axis point or verify the pile position during the construction process to ensure construction accuracy. The measurement of the construction axis must be carried out strictly in accordance with the designed coordinate points and confirmed to be correct after multiple verifications. The axis control point position of the construction site should be set away from the piling operation area, and protective measures should be taken to ensure its stability and reliability.

[0064] 5. Pile position numbering and placement: According to the designed pile position map, 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 placed according to the size requirements. This step ensures the accuracy of the pile position and provides strong support for subsequent piling operations.

[0065] 3. Production and installation of steel pipe 1

[0066] 1. Manufacturing and installation process of steel pipe 1: The steel pipe material is selected from Q355B or other high-quality steel materials according to design requirements. Taking the DN219 pipe diameter as an example, the wall thickness is set to 8mm. The end of the steel pipe (i.e. the bottom of the pile) is specially designed and welded with a step retaining ring 3. The 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 consistent with the outer diameter of the steel pipe pile. During installation, the retaining ring is first accurately placed inside the steel pipe, and then circumferential welding is performed to ensure a firm connection. In order to further improve the pull-out resistance of the retaining ring, we will also use more than 4 additional steel sheets with a size of 60mm wide × 80mm long × 6mm thick after welding to reinforce and weld the retaining ring and the steel pipe to form a more stable structure and improve the pull-out resistance.

[0067] The upper and lower sections of the steel pipe are connected by a sleeve 2 or a clamp, both of which are 200mm high. In the prefabrication stage, the sleeve or clamp is welded to one end of the steel pipe. During construction, the upper steel pipe is accurately inserted into the outer sleeve or clamp of the lower steel pipe, and then fine welding is performed to ensure the strength and stability of the connection. In particular, the steel pipe constructed in the rock layer is connected by butt welding to adapt to more complex geological conditions.

[0068] 2. Construction site segmentation strategy: The construction site is divided into indoor and outdoor work areas according to spatial conditions. Due to the limited indoor height, the steel pipe is divided into 2m long sections for operation; while the outdoor work area uses 6m long steel pipe sections. 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 at one end of the steel pipe. During construction, the upper end steel pipe is accurately inserted into the outer sleeve of the lower end steel pipe, and fine welding is performed to ensure the firmness and stability of the connection.

[0069] 3. Construction by following the pipe drilling method: This project innovatively adopts the following the pipe drilling method. This method allows the steel pipe to follow up synchronously while drilling the hole, greatly improving the construction efficiency and the quality of the hole.

[0070] 4. Steel pipe extension welding quality control: During the steel pipe extension welding process, the method of symmetrical welding along both sides is adopted to ensure the uniform distribution of welding stress. The weld quality is strictly implemented in accordance with the relevant standards for steel structure acceptance to ensure that the strength and sealing of the welded joint meet the design requirements.

[0071] 5. Application of efficient welding technology: In order to ensure the construction quality and progress, wire welding technology was selected. This technology has the advantages of fast welding speed, high weld quality, and easy operation. It can significantly improve the efficiency and quality of steel pipe welding and provide a strong guarantee for the smooth completion of the project.

[0072] 4. Pile construction

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

[0074] During the operation, the drill rod is precisely operated inside the steel pipe, and its bottom is tightly connected to a 6-inch impactor, and the impactor is further connected to a 219mm eccentric drill bit. This allows the tail of the drill bit to be firmly stuck on the retaining ring, so that during operation, the drill bit can powerfully hit and drill down against the retaining ring while rotating. The retaining ring and the pile body are connected together through a precise welding process. This design not only enhances the stability of the structure, but also can effectively bring the steel pipe pile into the ground along with the drilling process of the drill bit.

[0075] During the drilling process, huge air pressure plays a vital role, which can effectively flush impurities such as water, soil, silt, sand and rock debris in the formation out of the surface, thereby achieving penetration of the rock formation. This efficient drilling process ensures that there will be no mud left inside the steel pipe pile after drilling, and only clear water will be retained at the bottom.

[0076] 5. Hole forming at the anchor end

[0077] Then use a smaller drill bit to drill into the rock for the second time to a depth of 4 meters or more. This section is the anchoring section of the anti-floating pile and the rock layer. After the hole is drilled, there is no mud in the steel pipe pile and the rock section, and there is only clear water at the bottom.

[0078] 6. Unloading the drill pipe and moving the machine

[0079] Remove the drill rod and move the machine; after the drilling is completed, remove the drill rod and drilling tools in turn, move the machine to the next pile position, and at the same time add a pile cap to the top of the pile to prevent mud and sand from flowing in.

[0080] 7. Install the steel cage and connecting plate

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

[0082] 8. Pouring cement slurry or concrete

[0083] Grouting; Use 42.5R ordinary silicate cement to prepare pure cement slurry; Use drilling rigs and mud pumps to grout from bottom to top until pure cement slurry emerges from the ground hole; Use pure cement slurry for grouting in the pile hole, the cement strength grade is M30, the water-cement ratio is 0.5, and the pile body cement cube compressive strength is required to be not less than 30MPa; Use one-time grouting, and the grouting pressure is 2.5MPa; After the grouting pipe is lowered to the bottom of the hole, it is raised 50mm, and a high-pressure grouting pump is used. The catheter is inserted and grouting starts from the bottom of the hole until pure slurry emerges from the hole mouth.

[0084] 1) Use 42.5R ordinary Portland cement to prepare M30 pure cement slurry at a water-cement ratio of 0.5.

[0085] 2) Pure cement slurry is used for grouting in the pile hole. The cement strength grade is M30 and the water-cement ratio is 0.5. The compressive strength of the cement cube of the pile body is required to be no less than 30MPa.

[0086] 3) Use one-time grouting with a grouting pressure of 2.5MPa.

[0087] 4) Using a high-pressure grouting pump, insert the catheter 6 and start grouting from the bottom of the hole until pure slurry emerges from the hole mouth.

[0088] Alternatively, underwater self-compacting concrete may be poured through a conduit instead of the above-mentioned method of pouring cement slurry. The pouring sequence is from bottom to top, and the conduit is pulled out while pouring.

[0089] 9. Pile top anti-floating node

[0090] The anti-floating connection of the pile top, the connection between the steel pipe and the cap and the basement floor is connected by steel bars, 8 C20 steel bars are evenly distributed around the pile, and the length of the steel bar anchor pile head is not less than 70cm;

[0091] The invention discloses a construction method for anti-pull bearing steel pipe piles. The anti-floating steel pipe piles are new micro-pile foundations for enhancing the bearing capacity of foundations, the anti-groundwater buoyancy of buildings and the anti-lateral damage. It is particularly suitable for areas with high groundwater levels or low deep silt bearing capacity. The steel pipe is penetrated through soil layers, sand layers, and silt and driven into the rock layer by about 2 meters. Then, a smaller drill bit is used to drill into the rock for a second time at a depth of 4 meters or more (the depth is determined according to the anti-pull requirements). After the hole is formed, there is no mud in the steel pipe pile and the rock section, and only clear water is available at the bottom. A small steel cage is made, and the made steel cage is placed in the bottom of the steel pipe pile and drilled into the rock for a second time at a depth of 4 meters or more. A conduit is placed, and cement slurry, grouting material or self-flowing compacting concrete is injected. A small steel cage is placed in the bottom of the pipe pile for a second time at a depth of 4 meters or more. After solidification, the steel pipe pile can be effectively anchored to the underground rock layer. The anti-pull capacity of the steel pipe pile is significantly improved, the problem of building floating is solved, and the bearing capacity of the building is improved (the anti-floating anchor rod and anchor cable cannot improve the bearing capacity of the building). The safety, durability and reliability of the building are improved. The construction quality of this method is intuitive and controllable, and it changes the existing anti-floating anchor rods and anchor cables to resist the floating design and construction process of the building. It also significantly saves construction costs and construction period.

[0092] The construction quality of the pull-out bearing steel pipe pile construction method is intuitive and controllable, which changes the existing anti-floating anchor rods and anchor cables (the anchor rods and anchor cables are prone to failure due to uncontrollable forming quality such as mud wall protection, deep silt collapse holes, verticality, etc.) and resists the floating design and construction process of buildings. The pull-out bearing steel pipe pile construction method can significantly reduce the construction cost and construction period, while improving the anti-floating ability and bearing capacity of the building, and significantly improving the safety, durability and reliability of the building.

[0093] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

[0094] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for constructing a pull-out bearing steel pipe pile, characterized in that: The following steps are involved: Step S1. Leveling the site; Step S2. Pile position measurement and positioning; Step S3. Manufacturing and installing the steel pipe (1); Step S4. Pile construction; Step S5. Forming a hole at the anchoring end; Step S6. After the drilling is completed, remove the drill rod and move the machine; Step S7. Install the steel cage (4) and the connecting plate (5); Step S8. pouring cement slurry or concrete; Step S9. Pile top anti-floating connection; Step S10: Piling.

2. The method for constructing anti-pulling steel pipe piles according to claim 1, characterized in that: In step S3, a step retaining ring (3) is welded to the bottom end of the steel pipe (1), wherein the outer diameter of the upper half of the step retaining ring (3) is smaller than the inner diameter of the steel pipe (1), and the outer diameter of the lower half of the step retaining ring (3) is the same as the outer diameter of the steel pipe (1). After the step retaining ring (3) and the steel pipe (1) are welded and fixed, a plurality of steel sheets (31) are used for reinforcement welding to improve the pull-out resistance of the step retaining ring (3).

3. The method for constructing pull-out bearing steel pipe piles according to claim 2, characterized in that: In step S3, the upper and lower sections of the steel pipe (1) are connected by a sleeve or a clamp. When connecting, the sleeve or clamp is first welded to one end of the steel pipe in advance. During construction, the upper end steel pipe is inserted into the outer sleeve or clamp of the lower end steel pipe, and then welded. The connection between the steel pipes in the rock formation is butt welding.

4. The method for constructing pull-out bearing steel pipe piles according to claim 2, characterized in that: In step S4, the pile body is constructed by drilling with a pipe, and the hole is formed from the ground where the original concrete surface layer is broken. The hole is excavated downward with the original ground as ±0.00m. The drill rod operates in the steel pipe, and the bottom of the drill rod is connected to an impactor, and an eccentric drill bit is connected below the impactor. The tail of the drill bit is stuck on the retaining ring. During the operation, the drill bit rotates and hits the retaining ring while drilling downward. The retaining ring and the pile body are welded together, and at the same time, the steel pipe pile can be brought down downward; during the hole forming period, the water, soil, silt, sand, and rock debris in the stratum are flushed out of the ground due to the huge air pressure. The steel pipe successively passes through the soil layer, silt layer, sand layer, and at the same time, the rock is entered to 2 meters or more, and the operation is stopped. After the hole is formed, there is no mud in the steel pipe pile, and there is only clear water at the bottom.

5. The method for constructing pull-out bearing steel pipe piles according to claim 4, characterized in that: In step S5, the anchor end hole forming process uses a smaller model drill bit to drill into the rock for 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 the rock section, and there is only clear water at the bottom.

6. The method for constructing anti-pulling load bearing steel pipe piles according to claim 5, characterized in that: In step S7, the steel 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 clamped on the retaining ring at the bottom of the steel pipe, and a grouting hole (51) is left in the middle of the connecting plate as a channel for subsequent grouting.

7. The method for constructing anti-pulling load bearing steel pipe piles according to claim 6, characterized in that: In step S8, after the cement slurry or concrete is poured and solidified, the end of the steel pipe pile can be firmly anchored in the underground rock formation. Pure cement slurry is prepared using 42.5R ordinary silicate cement with a water-cement ratio of 0.

5. The compressive strength of the pile body cement cube is required to be not less than 30MPa. One-time grouting is adopted with a grouting pressure of 2.5MPa. After the grouting pipe is lowered to the bottom of the hole, it is lifted up by 50mm. Using a high-pressure grouting pump, the guide tube (6) is inserted to start grouting from the bottom of the hole until pure slurry emerges from the hole mouth.

8. The method for constructing pull-out bearing steel pipe piles according to claim 7, characterized in that: In step S9, the connection between the steel pipe and the foundation or the basement floor is made by steel bars, and 8 C20 steel bars (7) are evenly distributed around the pile, and the length of the steel bar anchoring the pile head is not less than 70 cm.

9. The method for constructing anti-pulling steel pipe piles according to claim 4, characterized in that: In the step S4, the eccentric drill bit is in the drilling state during the hole forming process, and is in the 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 curtains around; 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.

10. The method for constructing pull-out bearing steel pipe piles according to claim 3, characterized in that: In step S3, when welding the steel pipe, the welding should be performed symmetrically along both sides at the same time, and the quality of the weld should meet the relevant requirements for steel structure acceptance. In order to ensure the construction quality and progress, the steel pipe is welded by welding wire.

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