Controllable grouting steel pipe screw pile based on built-in piston extrusion and variable-diameter blades and construction method of controllable grouting steel pipe screw pile

Abstract

The invention discloses a controllable grouting steel pipe screw pile based on built-in piston extrusion and variable-diameter blades, comprising: a hollow steel pipe pile body, which is provided with a pile body, a pile top and a pile bottom, the pile top is provided with a connecting part flange plate, the pile bottom is provided with a pile tip, and the peripheral side wall of the pile body is provided with continuous variable-diameter screw blades from top to bottom in an attached manner, thereby forming a screw pile; and the piston pressurizing device is arranged from the pile top, is arranged in the hollow steel pipe pile body and is in sliding connection with the hollow steel pipe pile body. The spiral blades are subjected to structural innovation, the spiral pile is subjected to piston type grouting reinforcement, a corresponding construction method is matched, the spiral pile is converted into a pile foundation with'extrusion tightening 'as a main action mechanism, meanwhile, soil around the pile is reinforced through grouting, and the construction efficiency is improved. And the bearing capacity of the pile foundation is obviously improved on the basis of not greatly increasing the workload and working consumables.

Description

Technical Field

[0001] This invention relates to the field of grouting steel pipe piles, and in particular to a controllable grouting steel pipe helical pile based on built-in piston extrusion and variable diameter blades and its construction method. Background Technology

[0002] Pile foundations are the core component for ensuring structural stability in civil engineering. Steel pipe piles, with their advantages of high bearing capacity and wide construction adaptability, are widely used in various building and geotechnical engineering projects. To further enhance the synergy between steel pipe piles and the soil, grouting reinforcement technology has become a key supporting method, and the mainstream technologies currently include three main types.

[0003] Steel pipe spiral piles with pre-embedded grouting pipes reinforce the soil around the pile by pre-embedding grouting pipes in the pile body or spiral blades and then using an external high-pressure pump to deliver grout to the pile bottom or side after the pile is in place. The post-grouting technology for the pile side / pile bottom is mainly for traditional cast-in-place piles. Spiral piles with bottom grouting extend the grouting pipe to the pile tip and enlarge the pile end by grouting at the pile bottom during or after pile driving, thereby enhancing the end bearing capacity.

[0004] However, existing technologies have significant limitations: grouting pressure depends on external pumping stations, and long-distance transportation can easily lead to pressure loss; the grout outlet is also easily blocked by soil, affecting the grouting effect; the distribution of grout is greatly affected by the uniformity of soil, making it impossible to form a regular reinforcement pattern, resulting in unstable effects; grouting and pile driving are separate processes, requiring independent equipment and personnel, leading to long construction cycles and high costs; insufficient compaction and bonding at the pile-soil interface result in limited interface strengthening effects; and excessive grouting can easily cause material waste and environmental pollution. These problems urgently need to be solved. Summary of the Invention

[0005] The technical problem to be solved by this invention is to address the shortcomings of the prior art by providing a controllable grouting steel pipe spiral pile based on built-in piston extrusion and variable diameter blades. This invention innovates the structure of the spiral blades and uses a piston-type grouting reinforcement method for the spiral pile, along with corresponding construction methods, to transform the spiral pile into a pile foundation with "extrusion and tightening" as the main working mechanism. At the same time, grouting is used to reinforce the soil around the pile, thereby significantly improving the bearing capacity of the pile foundation without greatly increasing the workload and material consumption.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A controllable grouting helical pile for steel pipes based on built-in piston extrusion and variable diameter blades, comprising: Hollow steel pipe piles have a pile body, a pile top and a pile bottom. A connecting flange is provided at the pile top and a pile tip is provided at the pile bottom. Continuous variable diameter helical blades are attached to the outer perimeter of the pile body from top to bottom, thus forming a helical pile. The piston pressurization device is installed from the top of the pile and is built into the hollow steel pipe pile body and slidably connected to it.

[0007] Furthermore, the pile tip is conical and the cross-sectional area of ​​the pile tip gradually decreases from top to bottom. The pile tip adopts a closed conical pile tip, or an open conical pile tip, and is equipped with a one-way valve consisting of a high-strength spring and an alloy baffle. The pile body is provided with first grouting holes spaced apart, and the first grouting holes are arranged on both sides; The outer diameter of the variable diameter helical blade decreases continuously from the top of the pile to the bottom of the pile, forming a variable diameter blade.

[0008] Furthermore, the connection between the variable diameter helical blade and the pile body is opened by machine. The variable diameter helical blade has a gap space inside and a prefabricated ring is provided on its inner side. The variable diameter helical blade is arranged to fit and connect with the pile body through the prefabricated ring. Multiple second grouting holes are provided on the pressure-bearing surface of the variable diameter spiral blade.

[0009] Furthermore, the blade parameter settings for the variable diameter helical blade: The blade height H ranges from 50mm to 200mm, and is determined based on the required bearing capacity and the pile diameter D. Blade outer diameter = D + 2H; The leaf thickness is 8mm to 20mm, and can be appropriately thickened at the bottom and in hard soil areas.

[0010] Furthermore, a through hole is provided at the center of the connecting flange; the piston pressurizing device includes a piston rod, which is arranged inside the hollow steel pipe pile body. Its top end extends upward to the outside of the pile top through the through hole of the connecting flange, and its bottom end is connected to the piston disc. The piston disc is slidably connected to the inner peripheral wall of the hollow steel pipe pile body; the upper end of the piston rod is machined with standard threads or special bayonet.

[0011] Furthermore, the piston rod is multi-segmented, and the multi-segment piston rods are connected by precision thick-walled flanges pre-welded to the rod ends and high-strength prestressed bolts; Two rectangular sealing grooves are opened on the outer edge of the piston disc, and a sealing ring made of wear-resistant polyurethane material is installed in the groove to form a dynamic sealing system; the piston disc is made of 45 steel forgings by precision turning, and the tolerance of its diameter and the inner diameter of the pile body is precisely controlled.

[0012] Furthermore, the grouting pipe is configured independently of the piston pressurization device, and the grouting pipe is inserted into a reserved channel fixed in the center of the piston rod.

[0013] Furthermore, the top of the grouting pipe is equipped with a grouting pipe head, which is an open nozzle; The bottom end of the grouting pipe passes through the piston disc, and a sealing air bladder is installed at the bottom end of the grouting pipe. The grout outlet is tapered at the bottom end of the sealing air bladder. Both the sealing air bladder and the grout outlet are located in the hollow steel pipe pile cavity below the piston disc.

[0014] This invention also includes a construction method for a controllable grouting helical steel pipe pile based on built-in piston extrusion and variable diameter blades, comprising the following steps: S1. Construction preparation and pile assembly S1.1 Site leveling and surveying: Level the construction site and remove underground obstacles; Based on the design drawings, use a total station or GPS to accurately measure and lay out the lines, mark the center point of each pile position, and set up reliable protective piles; S1.2 On-site acceptance and assembly of pile components: Inspect the hollow steel pipe piles, variable diameter spiral blades, piston pressurization devices, and grouting pipes transported to the site; The pre-assembled piston pressurization device is inserted into the hollow steel pipe pile body from the top of the pile. At this time, the piston rod is in the top position. Not yet pressed down; Lay the grouting pipe along the reserved hole in the center of the piston rod, and ensure that the grout outlet at its lower end is located in the cavity below the piston disc; S2. Equipment positioning and pile hoisting S2.1, Specialized equipment in place: The specialized equipment is a drilling rig, which is a long spiral drilling rig with high torque, high axial pressure and the ability to provide additional downforce. Move the drilling rig to the pile location and level the machine platform using the hydraulic outriggers so that the center of its power head coincides with the center of the pile location, with a deviation of less than 20mm. S2.2 Pile hoisting and connection: Using a crane and specialized lifting equipment, the assembled helical piles are lifted vertically. Slowly move the pile body above the pile position. During the descent, ensure that the piston rod at the top of the pile is accurately aligned and securely locked with the clamp of the drilling rig's power head. At the same time, connect the upper end of the grouting pipe to the grout supply system on the ground. S3, Rotate and drive piles to design elevation. S3.1 Start the drilling rig. The pile body is connected to the drilling rig through the connecting flange. The drilling rig's power head drives the pile body to rotate at a constant speed. At the same time, the hydraulic system applies downward axial pressure. During this process, the variable diameter auger blades drill downward and tighten the soil, guiding the pile body to penetrate. S3.2 When the pile body sinks to the design elevation, immediately stop rotating and pressurizing to complete the pile driving process; at this time, the piston system is still in the initial locked state; S4, Segmented Piston Extrusion Grouting S4.1 Start the ground slurry mixing and conveying system: Mix cement slurry according to the designed water-cement ratio, and inject a predetermined amount of slurry into the cavity below the piston disc through the grouting pipe; S4.2 After the grout filling is completed, quickly disconnect the grouting pipe from the grout mixing and conveying system on the ground; S4.3 Release the temporary lock on the piston rod and connect the hydraulic system to the top of the piston rod; S4.4 Start the hydraulic system and apply a stable axial downward pressure to the piston rod. This pressure value should be pre-calculated and set according to the soil conditions and the design grouting pressure. S4.5 Under the constraint of the sealing ring, the piston disc moves downward at a constant speed along the inner wall of the pile, generating extremely high squeezing pressure on the grout in the grout cavity; S4.6 Under pressure, the grout is evenly sprayed from the variable diameter spiral blades and the grout outlet at the bottom of the pile body, successfully splitting, penetrating and filling the soil to form a ring-shaped cement-soil enlarged joint prototype; at the same time, some grout is pressed into the pile bottom to form the pile end reinforcement zone. S4.7 Segmented grouting: Repeat steps S4.1-S4.6, and perform segmented grouting from the bottom. Wait for each segment to initially solidify before proceeding to the next segment, ensuring that the grout in each segment can be evenly injected until the expected reinforcement is achieved.

[0015] Step S5, Pile Construction and Maintenance The grout solidifies and hardens on its own in the soil around the pile, eventually forming a composite pile foundation. Before the grout reaches sufficient strength, the top area of ​​the pile should be protected to avoid disturbance.

[0016] The present invention has the following beneficial effects: 1. The core of this invention lies in ensuring the coordinated operation of the variable-diameter helical blades and the built-in piston pressurization device. This structural feature is the foundation for achieving its high-pressure, directional grouting function. By innovating the structure of the core component of the helical pile—the helical blades—and implementing a piston-type grouting reinforcement method for the helical pile, along with corresponding construction methods, the helical pile is transformed from a pile type that mainly relies on "cutting" to advance into a pile foundation with "compression and tightening" as its main mechanism. Simultaneously, grouting reinforces the soil around the pile, achieving a significant increase in the bearing capacity of the pile foundation without significantly increasing the workload and material consumption.

[0017] 2. The blades of traditional helical piles are discrete and widely spaced. Their main function is to provide shear force and temporary support surface during pile driving. However, such widely spaced helical blades can disturb the soil and cause loosening. This invention arranges the helical blades continuously along the entire length of the pile, and the blade diameter gradually decreases from the top. This makes the installation process of helical piles faster and more stable. It is no longer like "drilling holes" in the soil, but more like screwing a giant screw into a solid foundation.

[0018] 3. This invention utilizes a piston-type grouting method to further strengthen the soil surrounding the helical pile, thereby increasing the side friction resistance around the pile and optimizing the pile's bearing capacity. Using a piston device inside the pile, the pile is pressed down after being screwed into the soil for segmented grouting. Holes are made on the blades, opening the connection between the blades and the pile body, allowing the grout to be evenly injected into the surrounding soil, optimizing the grouting reinforcement effect and forming a composite reinforced body, significantly improving the pile's bearing capacity.

[0019] 4. This invention constructs an integrated "pile driving-grouting-compaction" system: integrating pile driving, grouting, and compaction of the pile end and surrounding soil into a single system and continuous operation. The piston pressing process not only controls the grouting power, but the immense pressure it transmits also simultaneously performs secondary active compaction of the loose soil at the pile bottom and the surrounding soil, achieving an innovation from "passive infiltration" to "active splitting and compaction." Mechanical piston pressurization fundamentally eliminates the risks of pipe blockage and pressure loss, resulting in an extremely high grouting success rate. Grout distribution is controlled by a variable-diameter blade structure, ensuring consistent and controllable reinforcement effects with minimal variation in project quality. Seamlessly integrating the two key processes of pile driving and grouting, all operations are completed using the same dedicated main construction equipment, eliminating the cumbersome steps of grouting equipment entry, pipe laying, and secondary drilling required in traditional methods. This reduces the single-pile construction cycle by approximately 40%-60%, making it particularly suitable for large-scale projects with tight schedules.

[0020] 5. This invention combines the piston principle with pile foundation design in geotechnical engineering, and controls the spatial distribution of grout through a variable-diameter blade structure. This fundamentally solves the three key problems of grouting pressure, grout path, and reinforcement morphology, achieving precise, efficient, and highly reliable design and construction of grouting helical piles. Employing a core structure of continuous blades along the entire pile length, and using corresponding construction methods, the pile driving process of the helical pile is transformed into "active compression reinforcement," forming a high-strength, high-density reinforcement zone around the pile, ultimately significantly improving the bearing capacity and settlement control capability of the helical pile. This invention is applicable to various infrastructure projects with high bearing capacity requirements and adverse geological conditions (such as soft soil, loose sand, and fill), such as photovoltaic power stations, wind power foundations, municipal utility tunnel support, and building foundations. It is particularly suitable for projects requiring rapid construction and strict settlement control. Attached Figure Description

[0021] Figure 1 This is a perspective view of a controllable grouting steel pipe helical pile based on built-in piston extrusion and variable diameter blades according to the present invention.

[0022] Figure 2 This is a schematic diagram of the structure of a controllable grouting steel pipe spiral pile based on built-in piston extrusion and variable diameter blades according to the present invention.

[0023] Figure 3 This is a schematic diagram of the connection structure of the piston pressurization device and the grouting pipe of a controllable grouting steel pipe spiral pile based on built-in piston extrusion and variable diameter blades according to the present invention.

[0024] Figure 4 This is a schematic diagram of the grouting process of a controllable grouting steel pipe spiral pile based on built-in piston extrusion and variable diameter blades according to the present invention.

[0025] Figure 5 This is a basic flowchart of the construction method of the present invention.

[0026] The components include: 1. Grouting pipe; 2. Piston pressurization device; 3. Connecting flange; 4. Variable diameter spiral blade; 5. Second grouting hole; 6. Hollow steel pipe pile body; 7. Piston disc; 8. Sealing airbag; 9. Sealing ring; 10. Grout outlet; 12. First grouting hole; 13. Pile tip. Detailed Implementation

[0027] The present invention will now be described in further detail with reference to the accompanying drawings and specific preferred embodiments.

[0028] In the description of this invention, it should be understood that the terms "left side," "right side," "upper part," "lower part," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. "First," "second," etc., do not indicate the importance of the components, and therefore should not be construed as a limitation of this invention. The specific dimensions used in this embodiment are only for illustrating the technical solution and do not limit the scope of protection of this invention.

[0029] A controllable grouting helical pile for steel pipes based on built-in piston extrusion and variable diameter blades, comprising: Hollow steel pipe pile body 6, such as Figure 1 As shown, the hollow steel pipe pile 6 is a hollow cylinder with a pile body, a pile top (top) and a pile bottom (bottom). A connecting flange 3 is provided at the pile top, and a pile tip 13 is provided at the pile bottom. Continuous variable diameter helical blades 4 are arranged from top to bottom on the outer periphery of the pile body, thus forming a helical pile. The variable diameter helical blade structure actively guides and controls the grout, forming a regular "bamboo joint" reinforcement zone, which improves the bearing capacity.

[0030] Piston pressurizing device 2 is installed from the top of the pile and is built into and slidably connected to the hollow steel pipe pile body 6. The built-in piston pressurizing device can provide stable and extremely high mechanical pressure, eliminating the risk of grouting pressure loss and pipe blockage at the source, and improving the reliability of grouting.

[0031] The core of this invention lies in ensuring the coordinated operation of the variable-diameter helical blades and the built-in piston pressurization device. This structural feature is the foundation for achieving its high-pressure, directional grouting function. By innovating the structure of the helical blades—the core component of the helical pile—and implementing a piston-type grouting reinforcement method, along with corresponding construction methods, the helical pile is transformed from a pile type that mainly relies on "cutting" for advancement into a pile foundation with "compression and tightening" as its main mechanism. Simultaneously, grouting reinforces the soil around the pile, achieving a significant increase in the bearing capacity of the pile foundation without substantially increasing the workload and material consumption.

[0032] The following is in conjunction with the appendix Figure 1-3 The hollow steel pipe pile body and its component configuration described in this application are further described in detail below: like Figure 2 As shown, the connecting flange 3 is located at the top of the pile, and a through hole is provided at its center; the connecting flange 3 is used to connect with special equipment to drive the hollow steel pipe pile to rotate and press down the pile.

[0033] like Figure 2 As shown, pile tip 13 is located at the pile bottom, and the pile tip is conical with its cross-sectional area gradually decreasing from top to bottom. During implementation, the basic specifications of the hollow steel pipe pile body are first determined based on the engineering geological conditions and design bearing capacity requirements. Different types of pile tips can be configured at the pile bottom according to geological conditions. When it is necessary to strengthen the end bearing capacity, a closed-end conical pile tip can be used. Its material is the same as that of the pile rod, and it is firmly connected to the pile body by bevel welding. When pile tip grouting is required, an open-type conical pile tip is used, and a one-way valve consisting of a high-strength spring and an alloy baffle is installed to prevent a large amount of soil from flowing in during the pile driving process.

[0034] like Figure 1-2 As shown, the pile body is provided with first grouting holes 12 at intervals for grout to flow out. The first grouting holes are arranged on both sides to facilitate uniform grouting.

[0035] like Figure 1-2 As shown, the variable diameter spiral blade 4 is arranged spirally and continuously from top to bottom along the outer periphery of the pile body. The variable diameter spiral blade 4 starts from above the pile tip and extends continuously to the top of the pile or near the top of the pile.

[0036] Furthermore, the outer diameter of the variable diameter helical blade 4 decreases continuously from the top of the pile to the bottom of the pile, forming a variable diameter blade.

[0037] Traditional helical piles have discrete, widely spaced blades, which mainly provide shear force and temporary support during pile driving. However, such widely spaced helical blades can disturb the soil and cause it to loosen. This invention arranges the helical blades continuously along the entire length of the pile, and the blade diameter gradually decreases from the top, making the installation process of the helical pile faster and more stable. It is no longer like "drilling a hole" in the soil, but more like screwing a giant screw into a solid foundation.

[0038] Furthermore, the connection between the variable diameter spiral blade 4 and the pile body is opened by machine. The variable diameter spiral blade 4 has a gap space inside and a prefabricated ring is provided on its inner side. The variable diameter spiral blade 4 is arranged to fit and connect with the pile body through the prefabricated ring, so that the grout can enter the variable diameter spiral blade. Furthermore, multiple second grouting holes 5 are provided on the bearing surface of the variable diameter spiral blade 4, so that the grout can be injected into the soil through the blade during injection, making the grouting more uniform.

[0039] Furthermore, preferably, the blade material of the variable diameter helical blade is selected from metal plates with high strength, high toughness and good wear resistance.

[0040] Furthermore, the blade parameters for the variable diameter helical blade 4 are set as follows: Blade height H: The height H is defined as the distance from the outermost end of the blade to the pile axis, minus the pile radius. It is usually 50mm to 200mm, and is determined according to the required bearing capacity and the pile diameter D. Blade outer diameter = D + 2H; Leaf thickness: usually 8mm to 20mm, with appropriate thickening at the bottom and in hard soil areas.

[0041] The following is in conjunction with the appendix Figure 1-3 A further detailed description of the built-in piston pressurization device of this application is provided below: like Figure 2-3 As shown, the piston pressurizing device 2 includes a piston rod 7, which is inserted into the hollow steel pipe pile body 6. Its top end extends upward to the outside of the pile top through the through hole of the connecting flange 3, and its bottom end is connected to the piston disc 7. The piston disc 7 is slidably connected to the inner peripheral wall of the hollow steel pipe pile body 6.

[0042] Furthermore, the upper end of the piston rod is machined with standard threads or a special bayonet for connection with special equipment.

[0043] Furthermore, the specialized equipment is equipped with a high-frequency hydraulic vibrator, which is integrated into the top of the piston rod. When the piston is pressed down, vibration is applied synchronously, and the "vibration liquefaction" effect is used to temporarily reduce the viscosity of the slurry and the shear strength of the soil, so that the slurry can achieve a farther and more uniform penetration with lower pressure, which is particularly suitable for fine sand layers.

[0044] Furthermore, in engineering applications with large pile lengths, the piston rod can be manufactured in sections and connected on-site. Specifically, the piston rod is multi-sectioned, and the multi-section piston rods are connected by precision thick-walled flanges pre-welded to the rod ends and high-strength prestressed bolts.

[0045] Furthermore, two rectangular sealing grooves are opened on the outer edge of the piston disc 7, and a sealing ring 9 made of wear-resistant polyurethane material is installed in the groove to form a dynamic sealing system. This dynamic sealing system is safe and reliable, and can prevent the piston disc from rotating with the residual torsion that may occur in the pile body during the pressurization process, ensuring that the piston disc can only move in a straight line along the axial direction.

[0046] Furthermore, the piston disc 7 is made of 45 steel forgings by precision machining, and its diameter is precisely controlled to match the inner diameter of the pile body to ensure smooth sliding and minimal clearance.

[0047] Furthermore, the piston pressurizing device 2 also includes a guide structure, which includes a guide block disposed on the edge of the piston disc or the piston rod, and a guide groove disposed on the inner wall of the pile body. The piston pressurizing device is prevented from rotating during descent by the cooperation of the guide block and the guide groove.

[0048] This invention utilizes a piston-type grouting method to further strengthen the soil surrounding the helical pile, thereby increasing the side friction resistance around the pile and optimizing the pile's bearing capacity. Using a piston device inside the pile, the pile is pressed down after being screwed into the soil for segmented grouting. Holes are made in the piston blades, opening the connection between the blades and the pile body, allowing the grout to be evenly injected into the surrounding soil. This optimizes the grouting reinforcement effect, forming a composite reinforced body that significantly improves the pile's bearing capacity.

[0049] The following is in conjunction with the appendix Figure 1-4 Further detailed description of the grouting pipe in this application: like Figure 3 As shown, the grouting pipe 1 is configured independently of the piston pressurization device 2, and it is inserted and fixed in the reserved channel at the center of the piston rod; in the initial state (before pile driving), the grouting pipe passes through the reserved channel at the center of the piston rod and is fixed therein.

[0050] Furthermore, such as Figure 1-4As shown, the top of the grouting pipe 1 is equipped with a grouting pipe head, which is an open nozzle to ensure that the grout can be injected into the inner cavity; the bottom end of the grouting pipe 1 passes through the piston disc 7, and a sealing airbag 8 is equipped at its bottom end. A grout outlet 10 is located at the bottom end of the sealing airbag 8. Figure 1 , 4 As shown, the grout outlet 10 is tapered. Both the sealing airbag 8 and the grout outlet 10 are located within the hollow steel pipe pile cavity below the piston disc 7. Grout is filled into the cavity below the piston disc through the grouting pipe 1. Under downward pressure, the piston disc can squeeze the grout in the hollow steel pipe pile cavity below it into the surrounding soil through the first and second grout outlets. The sealing airbag prevents the grout from seeping into the area above the piston disc during the downward pressure process.

[0051] Figure 5 The above is a basic flowchart of the construction method of the present invention. Based on this basic flowchart, the present invention also provides a construction method for a controllable grouting steel pipe helical pile based on built-in piston extrusion and variable diameter blades, which specifically includes the following steps: S1. Construction preparation and pile assembly S1.1 Site leveling and surveying: Level the construction site and remove underground obstacles; Based on the design drawings, a total station or GPS is used to accurately measure and lay out the lines, mark the center point of each pile position, and set up reliable protective piles.

[0052] S1.2 On-site acceptance and assembly of pile components: Inspect the hollow steel pipe piles, variable diameter spiral blades, piston pressurization devices, and grouting pipes transported to the site; The pre-assembled piston pressurization device is inserted into the hollow steel pipe pile body from the top of the pile. At this time, the piston rod is in the top position. Not yet pressed down; Lay the grouting pipe along the reserved hole in the center of the piston rod, ensuring that the grout outlet at its lower end is located in the cavity below the piston disc.

[0053] S2. Equipment positioning and pile hoisting S2.1, Specialized equipment in place: The specialized equipment is a drilling rig, which is a long spiral drilling rig with high torque, high axial pressure and the ability to provide additional downforce. Move the drilling rig to the pile location and level the machine platform using the hydraulic outriggers so that the center of its power head coincides with the center of the pile location, with a deviation of less than 20mm.

[0054] S2.2 Pile hoisting and connection: Using a crane and specialized lifting equipment, the assembled helical piles are lifted vertically. Slowly move the pile body above the pile position. During the descent, ensure that the piston rod at the top of the pile is accurately aligned and securely locked with the clamp of the drilling rig's power head. At the same time, connect the upper end of the grouting pipe to the grout supply system on the ground (such as a grouting tank and a low-pressure delivery pump).

[0055] S3, Rotate and drive piles to design elevation. S3.1 Start the drilling rig. The pile body is connected to the drilling rig through the connecting flange. The drilling rig's power head drives the pile body to rotate at a constant speed. At the same time, the hydraulic system applies downward axial pressure. During this process, the variable diameter auger blades drill downward and tighten the soil, guiding the pile body to penetrate. S3.2 When the pile body sinks to the design elevation, immediately stop rotating and pressurizing to complete the pile driving process; at this time, the piston system is still in the initial locked state.

[0056] S4, Segmented Piston Extrusion Grouting S4.1 Start the ground slurry mixing and conveying system: Mix cement slurry according to the designed water-cement ratio, and inject a predetermined amount of slurry into the cavity below the piston disc through the grouting pipe; S4.2 After the grout filling is completed, quickly disconnect the grouting pipe from the grout mixing and conveying system on the ground; S4.3 Release the temporary lock on the piston rod and connect the hydraulic system to the top of the piston rod; S4.4 Start the hydraulic system and apply a stable axial downward pressure to the piston rod. This pressure value should be pre-calculated and set according to the soil conditions and the design grouting pressure. S4.5 Under the constraint of the sealing ring, the piston disc moves downward at a constant speed along the inner wall of the pile, like a huge "syringe push rod", which generates extremely high squeezing pressure on the grout in the grout cavity; S4.6 Under pressure, the grout is evenly sprayed from the variable diameter spiral blades and the grout outlet at the bottom of the pile body, successfully splitting, penetrating and filling the soil to form a ring-shaped cement-soil enlarged joint prototype; at the same time, some grout is pressed into the pile bottom to form the pile end reinforcement zone. S4.7 Segmented grouting: Repeat steps S4.1-S4.6, and perform segmented grouting from the bottom. Wait for each segment to initially solidify before proceeding to the next segment, ensuring that the grout in each segment can be evenly injected until the expected reinforcement is achieved.

[0057] The specialized equipment of this invention is a drilling rig, which is equipped with a drilling power head and a hydraulic system. The drilling power head can drive the pile to rotate at a uniform speed, while the hydraulic system applies downward axial pressure. The drilling power head is equipped with a clamp that can accurately align with and securely lock the piston rod at the top of the pile. In addition, the drilling hydraulic system is connected to the top of the piston rod, which can also apply a stable downward axial pressure to the piston rod, pushing the piston pressurization device to squeeze the grout.

[0058] Due to the strong soil-squeezing effect generated by the continuously variable diameter helical blades, the normal stress and shear strength of the soil around the pile are significantly increased, resulting in a substantial enhancement of the pile's side friction. Combined with mechanical piston pressurized grouting technology, this significantly improves the bearing capacity. Under the same geological conditions, compared with traditional discrete blade helical piles, the single pile bearing capacity of the helical pile of this invention can be significantly improved, with a more pronounced increase in soft soil layers. Furthermore, mechanical piston grouting eliminates grout leakage, protecting the construction site environment. Because of the higher bearing capacity, the amount of concrete and steel used can be reduced under the same load requirements, aligning with green building and sustainable development principles.

[0059] Mechanical piston pressurization fundamentally eliminates the risks of pipe blockage and pressure loss, resulting in an extremely high grouting success rate. Grout distribution is controlled by a variable-diameter blade structure, ensuring consistent and controllable reinforcement effects with minimal variation in project quality. Seamlessly integrating the two key processes of pile driving and grouting, all operations are completed using the same dedicated main construction equipment. This eliminates the cumbersome steps of traditional methods, such as grouting equipment arrival, pipe laying, and secondary drilling. The construction cycle for a single pile can be shortened by approximately 40%-60%, making it particularly suitable for large-scale projects with tight schedules.

[0060] S5, Pile Construction and Maintenance The grout solidifies and hardens on its own in the soil around the pile, eventually forming a "bamboo-shaped" composite pile foundation with extremely high bearing capacity, consisting of the original pile body and a series of regularly and continuously distributed "cement-soil enlarged joints". Before the grout reaches sufficient strength, the pile top area should be protected to avoid disturbance.

[0061] This invention constructs an integrated "pile driving-grouting-compaction" system: integrating the three steps of pile driving, grouting, and compaction of the soil at the pile end and around the pile into a single system and continuous operation. The piston pressing process not only controls the grouting power, but the enormous pressure it transmits also simultaneously performs secondary active compaction of the loose soil at the pile bottom and the soil around the pile, achieving an innovation from "passive infiltration" to "active splitting and compaction".

[0062] This invention combines the piston principle with pile foundation design in geotechnical engineering, and controls the spatial distribution of grout through a variable-diameter blade structure. This fundamentally solves three key problems: grouting pressure, grout path, and reinforcement morphology, achieving precise, efficient, and highly reliable design and construction of grouting helical piles. Employing a core structure of continuous blades along the entire pile length, and using corresponding construction methods, the pile driving process of the helical pile is transformed into "active compression reinforcement," forming a high-strength, high-density reinforcement zone around the pile, ultimately significantly improving the bearing capacity and settlement control capability of the helical pile. This invention is applicable to various infrastructure projects with high bearing capacity requirements and adverse geological conditions (such as soft soil, loose sand, and fill), such as photovoltaic power stations, wind power foundations, municipal utility tunnel support, and building foundations. It is particularly suitable for projects requiring rapid construction and strict settlement control.

[0063] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0064] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various equivalent transformations can be made to the technical solutions of the present invention, and these equivalent transformations all fall within the protection scope of the present invention.

Claims

1. A controllable grouting steel pipe helical pile based on built-in piston extrusion and variable diameter blades, characterized in that: Comprise: Hollow steel pipe pile body, which has a pile body, a pile top and a pile bottom, the pile top is provided with a connecting part flange, the pile bottom is provided with a pile tip, the outer peripheral side wall of the pile body is continuously arranged with variable diameter spiral blades from top to bottom, thereby forming a spiral pile; Piston pressurizing device, which is installed in the pile top, is built-in and slidably connected with the hollow steel pipe pile body.

2. The controllable cast-in-place concrete pile with built-in piston extrusion and variable-diameter vane based on steel pipe according to claim 1, characterized in that: The pile tip is conical and the cross-sectional area of the pile tip is tapered from top to bottom, the pile tip adopts a closed conical pile tip, or an open conical pile tip, and a one-way valve composed of a high-strength spring and an alloy baffle is installed; The pile body is provided with a first grouting hole at intervals, and the first grouting hole is arranged on both sides; The blade outer diameter of the variable diameter spiral blade is continuously decreased from the pile top to the pile bottom, forming a variable diameter blade.

3. The controllable cast-in-place concrete pile with built-in piston extrusion and variable-diameter blade according to claim 1, characterized in that: The connection between the variable diameter spiral blade and the pile body is punched by a machine, the variable diameter spiral blade has a gap space inside, a prefabricated ring is arranged on the inner side, and the variable diameter spiral blade is connected with the pile body through the prefabricated ring. A plurality of second grouting holes are arranged on the pressure bearing surface of the variable diameter spiral blade.

4. The controllable cast-in-place concrete pile with built-in piston extrusion and variable-diameter blade according to claim 1, characterized in that: The blade parameters of the variable diameter spiral blade are set as follows: The blade height H is in the range of 50mm to 200mm, which is determined according to the required bearing capacity and the pile diameter D; The blade outer diameter is D+2H; The blade thickness is 8mm to 20mm, which can be appropriately thickened in the lower part and hard soil area.

5. The controllable cast-in-place concrete pile with built-in piston extrusion and variable-diameter vane based on steel pipe according to claim 1, characterized in that: A through hole is arranged at the center of the connecting part flange; the piston pressurizing device comprises a piston rod, which is arranged in the hollow steel pipe pile body, the top end of the piston rod extends upward to the pile top outside through the through hole of the connecting part flange, the bottom end of the piston rod is connected with a piston disc, and the piston disc is slidably connected with the inner wall of the hollow steel pipe pile body; a standard thread or a special bayonet is machined on the upper end of the piston rod.

6. The controllable cast-in-place concrete pile with built-in piston extrusion and variable-diameter vane based on steel pipe according to claim 5, characterized in that: The piston rod is multi-sectioned, and the multi-sectioned piston rod is connected through a refined thick-wall flange plate and a high-strength prestressed bolt pre-welded on the rod end; Two rectangular sealing grooves are arranged on the outer edge of the piston disc, a sealing ring made of wear-resistant polyurethane material is arranged in the grooves, forming a dynamic sealing system; the piston disc is made of 45# steel forgings and is precisely machined by precise turning, and the diameter of the piston disc is accurately controlled in cooperation with the inner diameter of the pile body.

7. The controllable cast-in-place concrete pile with built-in piston extrusion and variable-diameter vane based on steel pipe according to claim 1, characterized in that: The grouting pipe is independently configured with the piston pressurizing device, and the grouting pipe is arranged in the reserved hole at the center of the piston rod.

8. The controllable cast-in-place concrete pile with built-in piston extrusion and variable-diameter vane based on steel pipe according to claim 1, characterized in that: A grouting pipe head is arranged at the top end of the grouting pipe, and the grouting pipe head is an open nozzle; The bottom end of the grouting pipe penetrates through the piston disc, and a sealing air bag is arranged at the bottom end of the grouting pipe, a grout outlet is arranged at the bottom end of the sealing air bag, the grout outlet is tapered, and the sealing air bag and the grout outlet are located in the cavity of the hollow steel pipe pile body below the piston disc.

9. A construction method of a controllable grouting steel pipe spiral pile based on built-in piston extrusion and variable diameter blade according to any one of claims 1-7, comprising the following steps: S1, construction preparation and pile body assembly S1.1, site leveling and measurement: Level the construction site and remove underground obstacles; According to the design drawing, use a total station or GPS to accurately measure and mark the center point of each pile position, and set a reliable pile guard; S1.2, on-site inspection and assembly of pile body components: Check the hollow steel pipe pile body, variable diameter spiral blade, piston pressurizing device and grouting pipe transported to the site; The pre-assembled piston pressurizing device is loaded into the hollow steel pipe pile body from the pile top, at this time the piston rod is in the top position, Not yet pressed down; The grouting pipe is laid along the reserved hole in the center of the piston rod, and the lower end of the grouting outlet is ensured to be located in the chamber below the piston disc; S2, equipment in place and pile body hoisting S2.1, special equipment in place: The special equipment is a drilling machine, and the drilling machine selected is a long spiral drilling machine with large torque, high axial pressure and the function of providing additional downward pressure; Move the drilling machine to the pile position, level the machine platform through the hydraulic support leg, and make the center of the power head coincide with the center of the pile position, with a deviation of less than 20mm; S2.2, pile body hoisting and connection: Use a crane to cooperate with a special lifting tool to vertically lift the assembled spiral pile; Slowly move the pile body above the pile position, and during the lowering process, accurately align and firmly lock the piston rod at the top of the pile with the gripper of the drilling machine power head; at the same time, connect the upper end of the grouting pipe with the slurry supply system on the ground; S3, rotary pile sinking to the design elevation S3.1, start the drilling machine, the pile body is connected with the drilling machine through the flange plate of the connecting part, the drilling machine power head drives the pile body to rotate at a constant speed, and at the same time the hydraulic system applies downward axial pressure; the variable-diameter spiral blade drills into and tightens the soil body downward in this process, guiding the pile body to penetrate; S3.2, when the pile body sinks to the design elevation, immediately stop rotating and pressurizing, and complete the pile sinking process; at this time, the piston system is still in the initial locked state; S4, segmented piston extrusion grouting S4.1, start the slurry mixing and conveying system on the ground: mix the cement slurry according to the designed water-cement ratio, and inject a predetermined amount of slurry into the chamber below the piston disc through the grouting pipe; S4.2, after the slurry filling is completed, quickly disconnect the grouting pipe from the slurry mixing and conveying system on the ground; S4.3, release the temporary locking of the piston rod, and connect the hydraulic system with the top of the piston rod; S4.4, start the hydraulic system to apply stable axial downward pressure to the piston rod, and the pressure value should be pre-calculated and set according to the soil conditions and the designed grouting pressure; S4.5, the piston disc moves downward at a constant speed along the inner wall of the pile body under the constraint of the sealing ring, generating extremely high extrusion pressure on the slurry in the slurry chamber; S4.6, the slurry is uniformly injected from the variable-diameter spiral blade and the grouting hole at the lower part of the pile body under the push of the pressure, successfully performing splitting, permeation and filling in the soil body, and forming a ring-shaped cement-soil enlarged section; at the same time, part of the slurry is pressed into the pile bottom, forming a pile end reinforcement area; S4.7, segmented grouting: repeat steps S4.1-S4.6 to push and press from the bottom segment, and wait for each segment to be preliminarily solidified before grouting the next segment, to ensure that each segment of slurry is uniformly injected into the expected reinforcement.

10. The construction method of the controllable cast-in-place concrete pile with steel pipe and spiral by built-in piston extrusion and variable diameter blade according to claim 9, characterized in that: It also includes: step S5, pile forming and curing: the slurry in the soil around the pile solidifies and hardens, finally forming a composite pile foundation; before the slurry reaches sufficient strength, the pile top area should be protected to avoid disturbance.

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