A diameter expanding super-high pressure stirring and spraying pile forming system and a construction method thereof

Abstract

This invention discloses an ultra-high pressure jet grouting pile system and its construction method, relating to the fields of foundation treatment and pile foundation construction technology in civil engineering. The system includes a drill rod module for forming pile holes and conveying the construction medium; a diameter expansion execution module for mechanically expanding the diameter at the bottom of the pile hole; a high-pressure jetting module integrated into the diameter expansion execution module for high-pressure fluid jetting and cutting the soil surrounding the pile hole; a drive and control module; a digital control module; a pile diameter detection module; and a pile frame support module. By integrating the drill rod module, diameter expansion execution module, high-pressure jetting module, drive and control module, digital control module, pile diameter detection module, and pile frame support module into a single construction system, the system achieves the orderly combination and coordinated operation of mechanical diameter expansion and high-pressure jetting cutting in a single process, significantly improving construction efficiency and reducing operational complexity, while effectively ensuring that the pile diameter meets the design requirements.

Description

Technical Field

[0001] This invention relates to the field of foundation treatment and pile foundation construction technology in civil engineering construction, specifically to an expanded diameter ultra-high pressure jet grouting pile system and its construction method. Background Technology

[0002] High-pressure jet grouting (HJJ) is a commonly used method for soft soil foundation treatment. Its principle involves injecting high-pressure grout from nozzles to directly cut and mix the surrounding soil, while simultaneously incorporating a curing agent to form a mixed pile with a certain strength and stability. This technology is suitable for various soft soil strata such as silt, fine sand, and clay, and is widely used in deep foundation pit support, foundation reinforcement, and seepage prevention projects. Traditional high-pressure jet grouting processes rely primarily on the kinetic energy of the grout itself to cut and mix the soil. The pile diameter and improvement effect are significantly affected by soil properties and depth, especially in dense silty sand layers, where extremely high pressure or repeated jetting is often required to achieve the designed pile diameter. This results in limited construction efficiency, high energy consumption, and the inability to guarantee the final pile diameter.

[0003] On the other hand, mechanical enlarged-base drill bit technology is also used in bored pile construction. By mechanically unfolding the drill bit flanges, an enlarged head is formed at the pile end to improve the pile end bearing capacity and pull-out resistance. However, this technology is generally only used for dry-operation or mud-wall bored piles, and the enlargement range is greatly limited by the mechanical structure. It usually cannot achieve large-scale soil improvement, nor does it have the function of on-site mixing and reinforcement.

[0004] Existing technologies have attempted to combine mechanical diameter enlargement with high-pressure jetting, but most are still at the stage of simply superimposing the two processes. For example, a mechanical drilling tool is first used to form a hole and enlarge the bottom, and then a jetting pipe is lowered for high-pressure grouting. This type of process has problems such as cumbersome construction procedures, low equipment conversion efficiency, and difficulty in controlling the quality of pile bonding. More importantly, existing equipment lacks an integrated system that can truly achieve the coordinated operation of "mechanical diameter enlargement" and "high-pressure jetting" on the same drilling tool and within the same process. This results in the regular space formed by mechanical diameter enlargement not being effectively utilized by high-pressure jetting, and excessive consumption of grout energy in the near-pile area, which restricts further expansion of the pile diameter and improvement of soil improvement effects. Summary of the Invention

[0005] The purpose of this invention is to provide an expanded diameter ultra-high pressure jet grouting pile system and its construction method, so as to solve the problems of limited pile diameter and pile depth, cumbersome process conversion, and insufficient coordination between mechanical expansion and hydraulic cutting in the existing high pressure jet grouting pile technology, which leads to low construction efficiency, insufficient energy utilization, and pile diameter that cannot meet design requirements.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a diameter-expanding ultra-high pressure jet grouting pile system, comprising: a drill rod module for forming a pile hole and conveying the construction medium; a diameter-expanding execution module connected to the drill rod module for mechanically expanding the diameter at the bottom of the pile hole; a high-pressure jetting module integrated on the diameter-expanding execution module for high-pressure fluid jetting and cutting the soil surrounding the pile hole; a drive and control module for controlling the coordinated actions of the drill rod module, the diameter-expanding execution module, and the high-pressure jetting module; a digital control module for digitally controlling and displaying parameters such as flow rate, pressure, speed, and verticality in real time; a pile diameter detection module for detecting whether the actual pile diameter meets the design requirements; and a pile frame support module for supporting and driving the drill rod module to perform drilling and lifting actions.

[0007] Furthermore, the drill pipe module includes an outer drill pipe for transmitting torque and drilling force; an internal transmission mechanism for controlling the operation of the enlargement execution module; and a fluid delivery channel, including a slurry channel and a gas channel, for delivering ultra-high pressure slurry (ultra-high pressure water) and compressed gas, respectively.

[0008] Furthermore, in the fluid delivery channel, the slurry channel is located inside the built-in transmission mechanism, and the gas channel is located between the built-in transmission mechanism and the outer drill pipe.

[0009] Furthermore, the diameter expansion execution module is a deployable mechanical diameter expansion mechanism, and its maximum diameter expansion in the deployed state is greater than the initial pile hole diameter formed by the drill pipe module.

[0010] Furthermore, the high-pressure jetting module includes at least one jetting port disposed on the outer edge of the diameter expansion execution module for jetting ultra-high pressure slurry or ultra-high pressure water outward to cut the soil.

[0011] Furthermore, the drive and control module can control the system to sequentially execute the following processes: drilling process, in which the drill rod module drills to the designed depth; mechanical expansion process, in which the expansion execution module is controlled to unfold and perform pre-stirring; high-pressure jetting and stirring process, in which the high-pressure jetting module is controlled to spray slurry, while the drill rod module is lifted and stirred; and drill retraction process, in which the expansion execution module is retracted and lifted to the borehole opening.

[0012] Furthermore, in the high-pressure jet mixing process, the gas channel simultaneously provides compressed gas to assist in slurry diffusion and soil mixing; the outer diameter of the drill rod module is smaller than the diameter of the pile hole it forms, so as to form an annular gap between the two for releasing construction pressure; the pile frame support module is a hydraulically driven pile frame system that can realize the vertical lifting and lowering of the drill rod module.

[0013] A method for expanding diameter ultra-high pressure jet grouting pile construction, implemented using the above-mentioned system, includes a drilling process in which the drill rod module is driven by the drill frame support module to drill down and form an initial pile hole, with the annular gap continuously releasing drilling pressure;

[0014] In the pre-mixing process of expanding the borehole, the built-in transmission mechanism drives the expansion execution module to unfold, and pre-mixes and crushes the soil in the mechanical expansion section at the bottom of the hole.

[0015] The shotcrete mixing process is improved by simultaneously opening the slurry channel and the gas channel of the drive and control module. The slurry is lifted and rotated in the expansion section. The high-pressure slurry (high-pressure water) cuts the soil through the injection nozzle, and the compressed gas assists in diffusion to achieve uniform mixing of soil and slurry.

[0016] During the drilling and hoisting process to the borehole opening, the diameter expansion module is retracted, and the drill rod module is hoisted to the borehole opening, completing the pile foundation.

[0017] Furthermore, in the grouting and mixing process, the drill rod lifting speed, grout pressure, and gas pressure are adjusted in real time by the digital control module and the drive and control module according to the resistance of the expansion section, so as to ensure that the pile diameter of the expansion section is consistent and the pile body is uniform. The pressure is continuously released through the annular gap throughout the process to prevent the ground from heaving and the grouting from going out of control due to pressure buildup in the hole. When the drill is pulled back and lifted, the expansion execution module remains in a contracted state to avoid disturbing the formed pile section.

[0018] Compared with existing technologies, the present invention provides an ultra-high pressure jet grouting pile system and its construction method for diameter expansion. By integrating a drill rod module, a diameter expansion execution module, a high pressure jetting module, a drive control module, a pile diameter detection module, a digital control module, and a pile frame support module into a single construction system, it achieves the orderly combination and coordinated operation of mechanical diameter expansion and high pressure jet cutting in a single process, significantly improving construction efficiency and reducing operational complexity, and effectively ensuring that the pile diameter meets design requirements. Furthermore, the system utilizes independently set grout and gas channels within the drill rod module, and leverages the annular gap between the drill rod's outer diameter and the borehole diameter to form a natural pressure relief channel. This effectively releases the ground pressure during ultra-high pressure construction, significantly reducing the squeezing and disturbance of the surrounding soil, making the system particularly suitable for environmentally sensitive areas. At the same time, the system achieves full-process visibility of drilling, diameter expansion, jetting, and lifting through digital control. This composite process of "mechanical diameter expansion + high-pressure jetting" not only provides an ideal free surface for hydraulic cutting by utilizing mechanical diameter expansion, allowing energy to be used more effectively for long-distance soil improvement, but also significantly increases the pile diameter without increasing power. Furthermore, the modular design gives the system good adaptability, enabling the formation of large-diameter, high-strength, and low-porosity mixing piles in deep silty soil and other strata. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0020] Figure 1 This is a schematic diagram of the overall structure provided for an embodiment of the present invention;

[0021] Figure 2 This is a schematic diagram of a portion of the construction process provided in an embodiment of the present invention;

[0022] Figure 3 This is a continuation of the schematic diagram of the construction process provided in the embodiment of the present invention.

[0023] Explanation of reference numerals in the attached figures:

[0024] 1. Drill pipe module; 11. External drill pipe; 12. Built-in transmission mechanism; 13. Fluid delivery channel; 131. Slurry channel; 132. Gas channel; 2. Diameter expansion execution module; 3. High-pressure injection module; 31. Injection port; 4. Drive and control module; 5. Digital control module; 6. Pile diameter detection module; 7. Pile frame support module. Detailed Implementation

[0025] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0026] As attached Figure 1-3 As shown:

[0027] Example 1:

[0028] This invention provides an expanded diameter ultra-high pressure jet grouting pile system, including a drill rod module 1, used to form a pile hole and transport the construction medium;

[0029] The diameter expansion execution module 2 is connected to the drill rod module 1 and is used to mechanically expand the diameter at the bottom of the pile hole;

[0030] The high-pressure jetting module 3, integrated on the diameter expansion execution module 2, is used to perform high-pressure fluid jetting and cutting on the soil around the pile hole;

[0031] The drive and control module 4 is used to control the coordinated actions of the drill pipe module 1, the diameter expansion execution module 2, and the high-pressure jetting module 3.

[0032] The digital control module 5, integrated on the pile support module 7, is used for digital control and real-time display of flow rate, pressure, speed, verticality, etc.

[0033] The pile diameter detection module 6 is integrated into the drive and control module 4 and is used to detect whether the actual pile diameter meets the design requirements.

[0034] The pile support module 7 is used to support and drive the drill rod module 1 to perform drilling and lifting actions.

[0035] The drill pipe module 1 includes an outer drill pipe 11, which is used to transmit torque and drilling force.

[0036] The built-in transmission mechanism 12 is used to control the action of the diameter expansion execution module 2;

[0037] The fluid transport channel 13 includes a slurry channel 131 and a gas channel 132, which are used to transport ultra-high pressure slurry (ultra-high pressure water) and compressed gas, respectively.

[0038] Furthermore, in the fluid transport channel 13, the slurry channel 131 is located inside the built-in transmission mechanism 12, and the gas channel 132 is located between the built-in transmission mechanism 12 and the outer drill pipe 11.

[0039] Among them, the diameter expansion execution module 2 is a deployable mechanical diameter expansion mechanism, and its maximum diameter expansion in the deployed state is greater than the initial pile hole diameter formed by the drill rod module 1.

[0040] Step S1-1: Assemble the drill rod module 1, diameter expansion execution module 2, high-pressure jetting module 3, drive and control module 4, digital control module 5, pile diameter detection module 6, and pile frame support module 7 into a diameter expansion ultra-high pressure jetting pile forming system.

[0041] Step S1-2: Start the drive and control module 4 to rotate the external drill rod 11 and drill down, while pumping high-pressure water through the slurry channel 131 until the designed hole depth is reached;

[0042] Step S1-3: Control the built-in transmission mechanism 12 to fully unfold the deployable mechanical expansion mechanism, expanding its maximum outer diameter from 600mm to 900mm, and complete the mechanical pre-mixing by rotating in the expansion section;

[0043] Steps S1-4: Switch the slurry channel 131 to deliver high-pressure water at a pressure of 40MPa, while simultaneously injecting 0.8MPa compressed air into the gas channel 132; the nozzle 31 sprays ultra-high-pressure water outward in the deployed state to cut the soil.

[0044] Step S1-5: Through the pile diameter detection module 6, control the diameter expansion execution module 2 to expand the diameter expansion drill bit blade to the designed pile diameter, and detect whether the actual pile diameter reaches the designed diameter;

[0045] Steps S1-6: Switch the grout channel 131 to deliver cement grout at a pressure of 40MPa, while simultaneously injecting 0.8MPa compressed air into the gas channel 132; the injection nozzle 31 sprays high-pressure grout outward in the deployed state and mixes the soil.

[0046] Steps S1-7: Raise drill rod module 1 at a uniform speed of 0.2m / min, maintaining a rotation speed of 15rpm, so that the slurry and soil are fully mixed to form a cement-soil pile with a diameter of not less than 1900mm;

[0047] Steps S1-8: After raising to the design elevation, shut down the high-pressure pumping system, retract the diameter expansion execution module 2, and continue raising until it reaches the borehole opening to complete the single pile construction.

[0048] Working principle: First, mechanical expansion is used to form an enlarged cavity at the bottom of the hole. Then, high-pressure water jets are used to cut the soil and compressed air is used to increase the cutting radius. After the hole diameter is qualified, grout is sprayed while lifting and stirring, so that the cement grout is evenly mixed with the in-situ soil and finally solidified into a high-strength pile with a diameter larger than the initial hole diameter.

[0049] Example 2:

[0050] This embodiment is basically the same as the previous embodiment, except that an expanded diameter ultra-high pressure grouting pile system is provided, and the high pressure jetting module 3 includes at least one jetting port 31 disposed on the outer edge of the expanded diameter execution module 2 for spraying ultra-high pressure grout outward to cut the soil.

[0051] Furthermore, the drive and control module 4 can control the system to execute the following procedures sequentially:

[0052] In the drilling process, drill rod module 1 is drilled to the designed depth;

[0053] In the mechanical diameter expansion process, the diameter expansion execution module 2 is deployed and pre-mixed.

[0054] In the high-pressure jetting and mixing process, the high-pressure jetting module 3 is controlled to spray slurry, while the drill rod module 1 is lifted and stirred.

[0055] In the drilling process, the enlargement module 2 is retracted and raised to the borehole opening.

[0056] Step S2-1: Erect the pile support module 7 on site in the silty clay soil layer, and vertically center the entire expanded diameter ultra-high pressure jet grouting pile system at the pile position;

[0057] Step S2-2: The drive and control module 4 instructs the external drill rod 11 to drill at a speed of 15 rpm, while simultaneously circulating bentonite slurry through the slurry channel 131 to protect the wall until the designed hole depth is reached;

[0058] Step S2-3: The expandable mechanical diameter expanding mechanism is expanded to a diameter of 1200mm through the built-in transmission mechanism 12, which is 100% larger than the initial aperture of 600mm. The mechanical pre-stirring is completed by repeatedly rotating up and down in the diameter expanding section.

[0059] Step S2-4: Start the high-pressure injection module 3, and spray high-pressure water at a pressure of 45MPa through the injection port 31. At the same time, the gas channel 132 provides 0.8MPa compressed air to assist in cutting.

[0060] Step S2-5: Through the pile diameter detection module 6, control the diameter expansion execution module 2 to expand the diameter expansion drill bit blade to the designed pile diameter, and detect whether the actual pile diameter reaches the designed diameter;

[0061] Step S2-6: Start the high-pressure injection module 3 and inject cement slurry mixed with 10% micro silica powder at a pressure of 45MPa through the injection port 31. At the same time, the gas channel 132 provides 0.8MPa compressed air to allow the formation pressure to be released quickly through the annular gap.

[0062] Step S2-7: Simultaneously lift and rotate drill rod module 1 at a speed of 0.2m / min, maintain grout flow rate of 120L / min, so that cement grout and silty clay are evenly mixed to form a reinforced pile with a diameter of 2200mm;

[0063] Step S2-8: Stop grouting and air supply and retract the enlargement execution module 2. After the drill rod module 1 is completely pulled out of the borehole, move it to the next pile position to continue construction.

[0064] Working principle: Silt clay has low strength and high porosity. First, mechanical expansion is used to pre-loosen the soil to reduce jetting resistance. Then, high-pressure water is used to cut the soil and microsilica powder is used to improve the activity of the slurry. Compressed air assists the slurry in forming air bubble channels in the soft clay, further improving the mixing uniformity, and finally forming a high-strength cement-soil pile with a large diameter and low replacement rate.

[0065] Example 3:

[0066] This embodiment is basically the same as the previous embodiment, except that in an expanded diameter ultra-high pressure jetting pile system, in the high pressure jetting and mixing process, the gas channel 132 simultaneously provides high pressure gas to assist the diffusion of slurry and the mixing of soil.

[0067] The outer diameter of drill pipe module 1 is smaller than the diameter of the pile hole it forms, so as to create an annular gap between the two for releasing construction pressure.

[0068] The pile support module 7 is a hydraulically driven pile support system that enables the vertical lifting and lowering of the drill rod module 1.

[0069] Step S3-1: Transport the expanded diameter ultra-high pressure jet grouting pile system to the dense sand layer site, and complete the horizontal leveling of the pile frame support module 7 and the verticality calibration of the system.

[0070] Step S3-2: Turn on the drive and control module 4 to drive the external drill rod 11 to penetrate the sand layer at a speed of 10 rpm, and at the same time pump the drag-reducing slurry through the slurry channel 131 until the designed hole depth is reached.

[0071] Step S3-3: Operate the built-in transmission mechanism 12 to unfold the expandable mechanical diameter expansion mechanism, expanding the outer diameter from 600mm to 1600mm, and repeatedly rotate up and down in the expansion section to complete the mechanical pre-mixing;

[0072] Step S3-4: High-pressure water is output from the slurry channel 131, with the pressure set at 55MPa, and sprayed through the injection port 31; 0.8MPa compressed air is simultaneously injected into the gas channel 132 to enhance the cutting and diffusion effect;

[0073] Step S3-5: Through the pile diameter detection module 6, control the diameter expansion execution module 2 to expand the diameter expansion drill bit blade to the designed pile diameter, and detect whether the actual pile diameter reaches the designed diameter;

[0074] Step S3-6: Cement slurry mixed with 2% high-efficiency water-reducing agent is output from the slurry channel 131, with the pressure set at 55MPa, and sprayed through the injection port 31; compressed air at 0.8MPa is injected simultaneously into the gas channel 132 to enhance the diffusion effect;

[0075] Steps S3-7: Raise drill rod module 1 at a uniform speed of 0.2m / min and maintain a rotation of 10rpm to ensure that the slurry forms a uniform mixing zone in the sand layer, and finally form a high-strength cement-soil pile with a diameter of 2600mm;

[0076] Step S3-8: Close all pump valves, retract the expansion actuator 2, and after the pile top is raised to the ground, complete the construction of this pile and prepare for the next pile.

[0077] Working principle: The dense sand layer has a large friction angle and strong permeability. First, mechanical expansion is used to destroy the original structure of the sand and reduce its density. Then, high-pressure water jets cut the contact points between sand particles. Water-reducing agent reduces the viscosity of the grout and improves its penetration and encapsulation capabilities. Compressed air forms instantaneous superpore pressure in the sand layer, which drives the grout to quickly fill the pores. The grout is sprayed, lifted and stirred at the same time to fully mix and bind the sand and grout, and finally form a high-density, large-diameter cement-soil pile.

[0078] Example 4:

[0079] Reference Figure 1-3The present invention provides a method for expanding diameter ultra-high pressure jet grouting pile construction, which is implemented using the above-mentioned system and includes a drilling process, wherein the drill rod module 1 is driven by the pile frame support module 5 to drill down to the design depth to form an initial pile hole, and the annular gap continuously releases the drilling pressure;

[0080] In the pre-mixing process of expanding the borehole, the built-in transmission mechanism 12 drives the expansion execution module 2 to expand to the maximum outer diameter, and pre-mixes and crushes the soil in the mechanical expansion section at the bottom of the hole.

[0081] Lifting the shotcrete mixing process: The drive and control module 4 simultaneously opens the slurry channel 131 and the gas channel 132, and rotates while being lifted in the expansion section. The high-pressure slurry is sprayed out through the injection port 31, and the compressed gas assists in diffusion, so as to achieve uniform mixing of soil and slurry.

[0082] During the drilling and hoisting process to the borehole opening, the diameter expansion module 2 is retracted, and the drill rod module 1 is hoisted to the borehole opening, completing the pile construction.

[0083] Furthermore, the drill rod lifting speed, slurry pressure, and gas pressure during the grouting and mixing process are adjusted in real time by the digital control module 5 and the drive and control module 4 based on the resistance of the enlarged section. This ensures that the pile diameter of the enlarged section is consistent and the pile body is uniform. Throughout the process, pressure is continuously released through the annular gap to prevent pressure buildup in the hole from causing ground heave and grouting loss of control. When the drill is pulled back and lifted, the enlarged execution module 2 remains in a contracted state to avoid disturbing the formed pile section.

[0084] During the drilling process, the drill rod module 1 is driven by the pile frame support module 5 to precisely drill to the designed depth. The annular gap formed between its outer diameter and the pile hole can continuously release drilling pressure, effectively reducing the initial disturbance to the surrounding strata. Subsequently, in the pre-mixing process, the built-in transmission mechanism 12 drives the diameter expansion execution module 2 to expand to the specified outer diameter, mechanically pre-mixing and breaking up the soil in a specific section at the bottom of the hole, creating a regular and loose initial free surface for subsequent high-pressure jetting.

[0085] In the core lifting and grouting mixing process, the drive and control module 4 simultaneously opens the grout channel 131 and the gas channel 132. During the lifting and rotation of the drill rod module 1, ultra-high pressure grout is ejected at high speed through the injection port 31, further cutting the pre-treated soil, while compressed gas is ejected through the gas channel 132, assisting the grout to further diffuse and mix evenly with soil particles, thereby forming an improved pile with a significantly increased diameter within the predetermined expansion section. The core advantage of this method is that the digital control module 5 can dynamically adjust the drill rod lifting speed, grout pressure, and gas pressure based on real-time feedback of construction resistance, ensuring the consistency of the pile diameter in the expansion section and the uniformity of the pile body material.

[0086] Finally, during the drilling and lifting process to the borehole opening, the diameter expansion module 2 is completely retracted before lifting, avoiding scraping and disturbance to the formed pile segment. Throughout the entire construction process, from drilling, diameter expansion, grouting and mixing to final lifting, the annular gap plays a crucial role in pressure release, effectively preventing construction risks such as ground heave or uncontrolled grout splashing that may be caused by pressure buildup in the borehole. In summary, this method, through the precise coordination of various modules and the optimized integration of processes, achieves efficient and controllable forming of large-diameter, high-strength, and low-disturbance piles, and is particularly suitable for engineering applications with strict requirements for settlement control and environmental conditions.

[0087] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A diameter-expanding ultra-high pressure jet grouting pile system, characterized in that, include, Drill rod module (1) is used to form pile holes and transport construction media; The diameter expansion execution module (2) is connected to the drill rod module (1) and is used to mechanically expand the diameter at the bottom of the pile hole; The high-pressure jetting module (3) is integrated on the diameter expansion execution module (2) and is used to perform high-pressure fluid jetting and cutting on the soil around the pile hole; The drive and control module (4) is used to control the coordinated actions of the drill pipe module (1), the diameter expansion execution module (2) and the high-pressure jet module (3); The digital control module (5) is used for digital control and real-time display of parameters such as flow rate, pressure, speed, and verticality; The pile diameter detection module (6) is used to detect whether the actual pile diameter meets the design requirements. The pile support module (7) is used to support and drive the drill rod module (1) and the drive and control module (4) to perform drilling and lifting actions and digital control.

2. The expanded diameter ultra-high pressure jet grouting pile system according to claim 1, characterized in that, The drill pipe module (1) includes an outer drill pipe (11) for transmitting torque and drilling force; An internal transmission mechanism (12) is used to control the operation of the diameter expansion execution module (2); The fluid transport channel (13) includes a slurry channel (131) and a gas channel (132), which are used to transport ultra-high pressure slurry (ultra-high pressure water) and compressed gas, respectively.

3. The expanded diameter ultra-high pressure jet grouting pile system according to claim 2, characterized in that, In the fluid transport channel (13), the slurry channel (131) is located inside the built-in transmission mechanism (12), and the gas channel (132) is located between the built-in transmission mechanism (12) and the outer drill rod (11).

4. A diameter-expanding ultra-high pressure jet grouting pile system according to claim 2 or 3, characterized in that, The diameter expansion execution module (2) is a deployable mechanical diameter expansion mechanism, and its maximum diameter expansion in the deployed state is greater than the initial pile hole diameter formed by the drill rod module (1).

5. The expanded diameter ultra-high pressure jet grouting pile system according to claim 4, characterized in that, The high-pressure jetting module (3) includes at least one jetting port (31) disposed on the outer edge of the diameter expansion execution module (2) for jetting ultra-high pressure slurry (ultra-high pressure water) outward to cut the soil.

6. The expanded diameter ultra-high pressure jet grouting pile system according to claim 5, characterized in that, The drive and control module (4) is able to control the system to execute the following procedures in sequence: In the drilling process, the drill rod module (1) is drilled to the designed depth; In the mechanical diameter expansion process, the diameter expansion execution module (2) is deployed and pre-stirred. In the high-pressure jetting and mixing process, the ultra-high pressure jetting module (3) is controlled to spray slurry (water), while the drill rod module (1) is lifted and stirred at the same time; In the drilling process, the enlargement module (2) is retrieved and raised to the borehole opening.

7. The expanded diameter ultra-high pressure jet grouting pile system according to claim 6, characterized in that, In the high-pressure jet mixing process, the gas channel (132) simultaneously provides compressed gas to assist the diffusion of slurry and the mixing of soil, and to help the replacement mud return to the ground through the annular gap; The outer diameter of the drill rod module (1) is smaller than the diameter of the pile hole it forms, so as to form an annular gap between the two for releasing construction pressure. The pile support module (7) is a hydraulically driven pile system that can realize the vertical lifting and lowering of the drill rod module (1).

8. A method for expanding diameter ultra-high pressure jet grouting pile construction, implemented using the system described in any one of claims 1 to 7, characterized in that, include, In the drilling process, the drill rod module (1) is driven by the drive and control module (4) to drill down and form the initial pile hole, and the annular gap continuously releases the drilling pressure; In the pre-mixing process of the enlarged drilling, the built-in transmission mechanism (12) drives the enlarged diameter execution module (2) to unfold and pre-mix and crush the soil in the mechanical enlarged diameter section at the bottom of the hole; Lifting the shotcrete mixing process: The drive and control module (4) simultaneously opens the slurry channel (131) and the gas channel (132), and lifts and rotates in the expansion section. The ultra-high pressure slurry cuts the soil through the injection port (31), and the compressed gas assists in diffusion, so as to achieve uniform mixing of soil and slurry. The drilling and lifting process to the borehole opening: The enlargement module (2) is retracted, and the drill rod module (1) is lifted to the borehole opening to complete the pile formation.

9. The method for expanding diameter ultra-high pressure jet grouting pile construction according to claim 8, characterized in that, In the lifting and grouting process, the drill rod lifting speed, grout pressure and gas pressure are adjusted in real time by the digital control module (5) and the drive and control module (4) according to the resistance of the expansion section, so as to ensure that the pile diameter of the expansion section is consistent and the pile body is uniform. The pressure is continuously released through the annular gap throughout the process to prevent the ground from heaving and the grouting from going out of control due to pressure buildup in the hole. When the drill is pulled back and lifted, the expansion execution module (2) remains in a contracted state to avoid disturbing the formed pile section.

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