Low-pressure jet grouting and bar planting integrated foundation reinforcement method and system

Abstract

The invention discloses a low-pressure jet grouting and bar planting integrated foundation reinforcement method and system. The method comprises the following steps that S1, a drilling machine is used for conducting drilling operation on a pile position at a preset position; s2, a grouting and bar planting system is used for conducting synchronous low-pressure jet grouting and bar planting operation on the drilled pile position; and S3, after low-pressure jet grouting and bar planting are completed, a reinforcement material at the top of the pile is trimmed, protection measures are taken, and meanwhile pile body maintenance is conducted. According to the method, the low-pressure rotary jet grouting technology is adopted, extrusion and disturbance of jet flow to surrounding soil are reduced, and the method is suitable for foundation reinforcement engineering of underground facility dense areas or sensitive areas with strict settlement control requirements; the tensile strength, the flexural rigidity and the overall structural performance of the pile body are improved, integrated synchronous continuous operation of grouting, reinforcement and pile forming is achieved, construction links are reduced, the construction efficiency is greatly improved, and the labor and machine input cost is reduced.

Description

Technical Field

[0001] This invention relates to the field of geotechnical engineering foundation treatment technology, specifically a low-pressure jet grouting and rebar-installation integrated foundation reinforcement method and system. Background Art

[0002] High-pressure jet grouting is a mature foundation reinforcement technology that has been widely used in soft soil foundation treatment, foundation pit support and seepage prevention projects. This technology injects cement grout (usually at a pressure of 20-40 MPa) into the stratum under high pressure, causing the grout jet to impact and destroy the in-situ soil structure. At the same time, it is forcibly mixed with the soil and solidifies to form a columnar cement-soil consolidation body with certain strength and integrity, thereby improving the bearing capacity of the foundation and reducing settlement.

[0003] However, despite the significant reinforcement effects of high-pressure jet grouting technology, its practical application still faces several limitations. Firstly, the high injection pressure causes strong disturbance to the surrounding soil during construction, potentially leading to additional deformation or even damage to nearby buildings, roads, or underground pipelines, thus limiting its application in environmentally sensitive areas or densely built-up areas. Secondly, high-pressure construction demands high-performance equipment and consumes a large amount of energy, resulting in higher construction costs. Furthermore, high-pressure jet grouting piles have relatively large diameters (typically φ500–φ2500 mm), making them difficult to implement in confined spaces or engineering scenarios requiring dense pile placement. More importantly, traditional jet grouting piles rely primarily on the compressive strength of the cement-soil mixture, exhibiting weak bending, tensile, and pull-out resistance, which is insufficient when bearing horizontal loads, resisting buoyancy, or used as composite load-bearing structures. To address this issue, based on existing technologies, attempts have been made to incorporate reinforcing materials such as steel bars, steel pipes, or I-beams into the jet grouting pile body to improve its overall mechanical properties. However, current reinforcement methods are mostly post-construction, meaning that after the initial formation of the jet grouting pile, reinforcement materials are implanted into the pile using methods such as vibro-compaction, static pressure, or secondary drilling. These methods not only disturb the existing cement-soil pile, affecting its integrity and quality, but also increase construction steps and reduce efficiency. Furthermore, it is difficult to ensure the verticality and central position of the reinforcement material during implantation, severely impacting the reinforcement effect and structural reliability. Therefore, existing high-pressure jet grouting technology has significant shortcomings in terms of environmental adaptability, construction economy, spatial applicability, and structural performance, especially in foundation reinforcement projects requiring high precision, low disturbance, small diameter, and good bending and tensile strength. To address these issues, a low-pressure jet grouting integrated reinforcement method and system for foundation reinforcement is proposed. Summary of the Invention

[0004] The purpose of this invention is to provide a low-pressure jet grouting and rebar-integrated foundation reinforcement method and system to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a low-pressure jet grouting and rebar-integrated foundation reinforcement method, comprising the following steps: S1. Use a drilling rig to drill holes at the pre-set pile positions; S2. Use a grouting and rebar installation system to perform simultaneous low-pressure jet grouting and reinforcement work on the pile positions after drilling is completed. S3. After completing the low-pressure jet grouting and reinforcement, the reinforcement material at the top of the pile is repaired and protected, and the jet grouting pile body is cured at the same time.

[0006] As a further aspect of the present invention: before drilling in step S1, the grout used for jet grouting and the reinforcing material implanted in the pile body need to be pretreated.

[0007] As a further aspect of the present invention: when preparing the reinforcing material, in areas rich in groundwater, corrosion-resistant FRP fiber reinforcement is used and the surface is roughened by sandblasting to increase the bonding force between the jet grouting pile body and the reinforcing material; while in high-load scenarios, ribbed steel bars are used and rust-proof treatment is performed to increase the corrosion resistance of the steel bars.

[0008] As a further aspect of the present invention: in step S2, during the low-pressure rotary jet grouting process, the grouting pressure, grouting flow rate, rotation speed, and lifting speed are monitored and recorded in real time.

[0009] As a further aspect of the present invention, step S2 specifically includes the following steps: S21. Place the reinforcing material into the jet nozzle using a clamp, ensuring that the lower end of the reinforcing material is in contact with the lower end of the jet nozzle. S22. Lower the jet grouting pipe containing reinforcing material to the bottom of the borehole; S23. Depending on the formation type, inject cement grout into the borehole at a preset grouting pressure. S24. Based on the geological type, operate at the preset rotary nozzle rotation speed and lifting speed; S25: After the jet grouting pipe starts jet grouting and rises to the preset height, the clamp is released, so that the reinforcing material is separated from the jet grouting pipe. The reinforcing material stops rising with the jet grouting pipe and remains in the jet grouting pile body.

[0010] As a further aspect of the present invention: in step S23, for clay strata, the grouting pressure of the cement grout is 5-12 MPa; while for sandy strata, the grouting pressure of the cement grout is 12-15 MPa.

[0011] As a further aspect of the present invention: in step S24, for clay formations, the rotational speed of the jet nozzle is 10-20 rpm and the lifting speed is 15-25 cm / min; for sandy formations, the rotational speed of the jet nozzle is 20-35 rpm and the lifting speed is 8-15 cm / min.

[0012] A low-pressure jet grouting and rebar-installation integrated foundation reinforcement system includes a drilling rig system, a rebar processing system, a grout preparation and delivery system, a grouting and rebar-installation system, and a control system. Drilling rig system, used for drilling operations on the foundation; A reinforcement processing system is used to pre-treat reinforcement materials implanted in the foundation; A grout preparation and delivery system is used to prepare grouting grout and deliver it to the grouting operation point. The grouting and rebar installation system is used to achieve simultaneous low-pressure jet grouting and reinforcement material implantation during construction. The control system is used to coordinate and control the operating parameters and work processes of each system, and is connected to the drilling rig system, grout preparation and delivery system and grouting and rebar installation system respectively.

[0013] As a further aspect of the present invention: the grouting and rebar installation system includes a jet grouting pipe and a clamp, the jet grouting pipe and the clamp are connected to a grout preparation and delivery system, the jet grouting pipe includes an internal pipe and an external pipe, the internal pipe and the external pipe are connected by a gasket located at its bottom, and two nozzles arranged horizontally at 120° are installed on the outer periphery of the external pipe near the bottom.

[0014] As a further aspect of the present invention: the nozzle includes an integrally formed hemisphere and a bolt body, the bolt body being threadedly connected to an external pipe, and both the hemisphere and the bolt body having interconnected spray channels, one end of which is open, and the spray angle is at an obtuse angle to the radial direction of the swirl nozzle. The end of the hemisphere away from the bolt body has a groove on the same axis as the nozzle outlet direction.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. This application utilizes low-pressure jet grouting technology, which effectively reduces the compression and disturbance of the surrounding soil by the jet stream, avoiding uneven settlement of adjacent buildings or deformation of underground pipelines caused by construction. It is particularly suitable for foundation reinforcement projects in areas with dense underground facilities or sensitive areas with strict settlement control requirements. Moreover, the diameter of the jet grouting piles formed by low-pressure grouting is smaller, and the pile diameter can be controlled between φ300 and φ600 mm. Compared with traditional large-diameter piles, it significantly reduces cement consumption and grout consumption, thereby reducing material costs and energy consumption. At the same time, the small pile diameter design is more suitable for high-density pile layout requirements, broadening the application prospects in space-constrained sites. Furthermore, the equipment required for small-diameter jet grouting pile construction is small in size, highly integrated, and the various functional modules work together, making operation simple. It can be flexibly arranged and constructed in narrow and complex sites, significantly improving construction efficiency and project adaptability.

[0016] 2. This application, by simultaneously implanting reinforcing materials during the jet grouting process, integrates the reinforced body with the cement-soil pile body, significantly improving the tensile strength, bending stiffness, and overall structural performance of the pile. This effectively compensates for the weak tensile and bending resistance of traditional pure cement-soil piles, simultaneously meeting the structural requirements of various complex working conditions such as vertical bearing, foundation pit support, and pull-out anchoring, thus expanding the application scope of jet grouting pile technology. Furthermore, the simultaneous implantation of reinforcing materials during the jet grouting process avoids secondary disturbance to the already formed pile body caused by traditional post-reinforcement processes, effectively ensuring the continuity and integrity of the pile body and the centering and verticality of the reinforcing materials, improving the reliability and stability of the pile quality. Finally, the organic integration of grouting and pile formation with the reinforcement implantation process achieves integrated, synchronous, and continuous operation of "grouting-reinforcement-pile formation," reducing construction steps, avoiding waiting between multiple processes, significantly improving construction efficiency, and reducing labor and machinery input costs. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the low-pressure jet grouting and rebar-integrated foundation reinforcement method of the present invention; Figure 2 This is a schematic diagram of the overall structure of the low-pressure jet grouting and rebar-integrated foundation reinforcement system of the present invention; Figure 3 This is a schematic diagram of the overall structure of the connector of the present invention; Figure 4 This is a schematic diagram of the combination of the swirl nozzle and the reinforcing material of the present invention; Figure 5 This is a schematic diagram of the dual-nozzle spray area of ​​the present invention; Figure 6 This is a schematic diagram of the nozzle of the present invention; In the diagram: 1. Drilling rig system; 11. Drilling rig moving platform; 12. Drill frame; 13. Power head; 14. Lifting platform; 2. Reinforcing steel processing system; 3. Slurry preparation and conveying system; 31. Water supply pipeline; 32. Mixer; 33. Slurry storage tank; 34. Grouting pump; 35. Slurry delivery pipeline; 351. Slurry delivery hose; 352. Connector; 3521. Connector housing; 3522. Connector mandrel; 3523. Fixing ring; 3524. Bearing; 3525. Sealing ring 3526. Jet grouting pipe connector; 3527. Grouting hose connector; 4. Grouting and rebar installation system; 41. Jet grouting pipe; 42. Nozzle; 421. Hemisphere; 422. Bolt body; 423. Spraying channel; 43. Clamp; 411. External pipe; 412. Internal pipe; 413. Gasket; 414. Sealing bolt; 5. Control system; 51. Sensor module; 52. Control terminal; 53. Controller module; 6. Reinforcing material; 7. End piece; 8. Jet grouting pile body. Detailed Implementation

[0018] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 making creative efforts are within the scope of protection of the present invention.

[0019] Please see Figure 1 In this embodiment of the invention, a low-pressure jet grouting and rebar-integrated foundation reinforcement method includes the following steps: S1. Use a drilling rig to drill holes at the pre-set pile positions; Specifically, before drilling in step S1, the site is cleaned and the pile positions are accurately measured and located. Then, the drilling system 1, reinforcement processing system 2, grout preparation and delivery system 3, grouting and rebar installation system 4, and control system 5 are installed, and the systems are debugged to ensure that parameters such as pressure, flow rate, and rotation speed are controllable. Next, cement slurry (or cement-bentonite slurry, cement-fly ash slurry, etc.) is mixed according to the designed water-cement ratio to ensure that the slurry is uniform, has good fluidity, and is free of sediment (admixtures can be added according to design requirements to meet specific requirements). In this embodiment, PO 42.5 cement is preferably used, the designed water-cement ratio is 0.9, and 0.5% cellulose ether is added. According to the design requirements, the reinforcing material 6 is straightened, cut, processed, and surface-treated according to the designed pile length (the allowable curvature of the reinforcing material 6 after straightening is ≤2 mm / m). In this embodiment, preferably, the reinforcing material 6 uses 20mm HRB400 steel bars, with an allowable curvature of ≤2 mm / m. The steel bars are straightened by adjusting the diameter (mm / m) and cut to a designed pile length of 8m. The lower end of the reinforcing bar is welded with end plates 7, and then rust-removed and painted. Specifically, when preparing and pre-treating the reinforcing material 6, the appropriate material is selected based on stratum detection. For areas rich in groundwater, corrosion-resistant FRP fiber reinforcement is preferred, and its surface is roughened by sandblasting to increase the bond strength between the jet grouting pile body 8 and the reinforcing material 6. For high-load scenarios, ribbed steel bars are preferred, and rust-proofing treatment is applied. To increase the corrosion resistance of the reinforcing steel, a pilot hole is drilled at the designed pile location using the drilling system 1. The drilling process must maintain verticality, and the drilling diameter should be slightly larger than the diameter of the jet grouting pipe 41. The depth should reach the designed pile bottom elevation. The verticality deviation of the drilling should be ≤0.5%. Preferably, the drilling diameter should be 20mm larger than the outer diameter of the jet grouting pipe 41. In this embodiment, the diameter of the jet grouting pipe 41 is 75mm, and the drilling diameter is 95mm. If the strata are prone to collapse (such as sand layers, miscellaneous fill, etc.), mud slurry wall protection or casing can be used for follow-up.

[0020] S2. Using the grouting and rebar installation system 4, low-pressure jet grouting and rebar installation are carried out simultaneously at the drilled pile positions. Step S2 specifically includes the following steps: S21. Insert the reinforcing material 6 into the jet nozzle 41, and then clamp the reinforcing material 6 located in the jet nozzle 41 using the clamp 43, so that the end piece 7 at the lower end of the reinforcing material 6 is in contact with the lower end of the jet nozzle 41. The shape of the end piece 7 is not limited, but its outer circle diameter should be smaller than the borehole diameter. In this embodiment, preferably, the end piece 7 is circular, and the diameter of the circular end piece 7 is consistent with the diameter of the outer pipe 411 of the jet nozzle 41. This can not only further increase the pull-out resistance of the reinforcing material 6, but also reduce the entry of foreign objects into the inner pipe 412 of the jet nozzle 41 during the lowering of the jet nozzle 41 by fitting the end piece with the lower end of the jet nozzle 41.

[0021] S22. Lower the swirl nozzle 41 with the reinforcing material 6 inserted to the bottom of the borehole; S23. Depending on the formation type, inject cement grout into the borehole at a preset grouting pressure. In step S23, if the stratum is clay, the grouting pressure of the cement grout is 5-12 MPa; if the stratum is sandy, the grouting pressure of the cement grout is 12-15 MPa. S24. Based on the geological type, operate at the preset rotation speed and lifting speed of the rotary nozzle 41; In step S24, if the formation is clay, the rotation speed of the jet nozzle 41 is 10~20 rpm and the lifting speed is 15~25 cm / min; if the formation is sandy, the rotation speed of the jet nozzle 41 is 20~35 rpm and the lifting speed is 8~15 cm / min. In this embodiment, preferably, the formation type is clay, the grouting pressure is 8 MPa, the rotation speed of the jet nozzle 41 is 14 rpm, and the lifting speed is 18 cm / min.

[0022] S25: After the jet grouting pipe 41 starts jet grouting and rises to the preset height, the clamp 43 is released, so that the reinforcing material 6 is separated from the jet grouting pipe 41, and the reinforcing material 6 stops rising with the jet grouting pipe 41 and remains in the jet grouting pile body. In use, the jet grouting pipe 41 is first lowered to the designed pile bottom elevation, the grouting and rebar installation system 4 is activated, grouting begins, and the jet grouting pipe 41 is raised simultaneously. When the jet grouting pipe 41 is raised to about 20cm from the pile bottom, the cement-soil mixture formed by the grouting has initially formed at the bottom of the hole, forming an initial jet grouting pile body 8 with a thickness of about 20cm. This initial jet grouting pile body 8 provides the necessary lateral support and protective layer thickness for the subsequent implantation of the reinforcing material 6, effectively preventing the reinforcing material 6 from being displaced or damaged due to soil disturbance in the early stage of implantation. Subsequently, the clamp 43 automatically releases, allowing the reinforcing material 6 to detach from the jet grouting pipe 41. At this time, the reinforcing material 6 stops being raised with the jet grouting pipe 41 and remains inside the already formed jet grouting pile body 8 to ensure that the bottom of the reinforcing material 6 has a sufficient cement-soil protective layer. During the continuous lifting of the jet grouting pipe 41, the reinforcing material 6 is simultaneously inserted into the central area of ​​the jet grouting pile body 8 through the implantation device. Due to the moderate grout pressure used in low-pressure jet grouting, the cement grout is fully mixed with the in-situ soil, exhibiting good fluidity and plasticity. Under the action of grouting pressure and the self-weight of the grout and soil, the reinforcing material 6 can naturally center and be evenly wrapped in the center of the jet grouting pile body 8, achieving a tight bond with the cement-soil matrix. During construction, key process parameters, including grouting pressure, grouting flow rate, jet grouting pipe rotation speed, and lifting speed, are monitored and recorded in real time to ensure that all parameters meet the design requirements, thereby forming a cement-soil pile body with a small diameter, regular geometric shape, and uniform quality. This is beneficial for the accurate positioning of the reinforcing material 6 and the uniform stress of the overall structure.

[0023] Through the above construction process, the reinforcing material 6 is simultaneously and automatically implanted during the jet grouting process, eliminating the need for additional drilling or secondary construction, thus significantly improving construction efficiency. At the same time, the reinforcing material 6 is located at the center of the jet grouting pile body 8, fully integrating with the cement and soil, significantly enhancing the pile body's bending, tensile, and overall bearing capacity. This solves the technical problems of traditional jet grouting piles being brittle and having low tensile strength. The automatic implantation of the reinforcing material 6 is completed simultaneously with low-pressure jet grouting, achieving integrated molding of the reinforcing material 6 and the jet grouting pile body 8. This method has advantages such as convenient construction, controllable quality, and superior structural performance, making it suitable for various foundation treatment and foundation pit support projects.

[0024] S3. After completing the low-pressure jet grouting and reinforcement, the reinforcement material 6 at the top of the pile is repaired and protected. The next step of quality inspection and construction can only be carried out after the jet grouting pile body 8 reaches a certain strength. The quality inspection should include verifying the integrity of the pile body by low strain method, verifying the bearing capacity by static load test, verifying the reinforcement effect by pull-out test, and verifying the strength of the pile body by core sampling strength test, to ensure that the reinforcement effect meets the design requirements.

[0025] Please see Figure 2-6A low-pressure jet grouting and rebar-installation integrated foundation reinforcement system includes a drilling system 1, a rebar processing system 2, a grout preparation and delivery system 3, a grouting and rebar-installation system 4, and a control system 5. Drilling system 1, used for drilling operations on the foundation; The reinforcement processing system 2 is used to pre-treat the reinforcement material 6 implanted in the foundation; Grout preparation and delivery system 3 is used to prepare grouting grout and deliver it to the grouting operation point; The grouting and rebar installation system 4 is used to realize the construction of simultaneous low-pressure jet grouting and reinforcement material 6; The control system 5 is used to coordinate and control the operating parameters and work processes of each system, and is connected to the drilling system 1, the slurry preparation and delivery system 3 and the grouting and rebar installation system 4 respectively.

[0026] Specifically, the drilling rig system 1 includes a drilling rig mobile platform 11, a drill frame 12, a power head 13, and a lifting platform 14. The drilling rig mobile platform 11 provides the entire drilling rig system 1 with walking function and construction power, and serves as the installation and support foundation for other equipment, ensuring that the equipment can be flexibly positioned and operate stably on the construction site. The drill frame 12 is fixed on the mobile platform 11 and is used to support and guide the drilling tools. By adjusting its tilt angle and verticality, the drilling direction and hole quality are precisely controlled. The power head 13 is installed on the drill frame 12 and is driven by a power unit to drive the drill rod and jet grouting pipe 41 to rotate, realizing drilling and jet grouting operations. The lifting platform 14 controls the smooth lowering and uniform lifting of the drill rod and jet grouting pipe 41 through a winch mechanism or hydraulic system, ensuring that the lifting speed meets the process requirements during construction and ensuring the continuity and uniformity of the jet grouting pile body 8.

[0027] The reinforcement material processing system 2 includes a straightening machine, a cutting machine, a sandblasting machine, as well as welding and painting equipment. It is used to straighten, cut, remove rust or roughen the surface of the reinforcement material 6, weld and connect it, and apply an anti-rust coating. This system enables integrated processing of the reinforcement material 6. Through this system, reinforcement material 6 that meets the design requirements and the matching needs of construction equipment can be efficiently produced, ensuring that its dimensional accuracy, surface condition and durability meet the technical standards for engineering applications such as reinforced jet grouting piles.

[0028] The slurry preparation and delivery system 3 includes a water supply pipeline 31, a mixer 32, a slurry storage tank 33, a grouting pump 34, and a slurry delivery pipeline 35, used for mixing, storing, and delivering uniform cement slurry that meets design requirements. Specifically, during construction, mixing water is supplied to the mixer 32 through the water supply pipeline 31, and the water is thoroughly mixed with cement and other materials in the mixer 32 to prepare a uniform cement slurry. The prepared slurry is temporarily stored in the slurry storage tank 33 and then pressurized and delivered by the grouting pump 34. In this embodiment, preferably... The grouting pump 34 adopts a plunger pump or screw pump, which has the advantages of stable pressure and controllable delivery volume, and can meet the precise requirements of flow rate and pressure for jet grouting. The grout delivery pipeline 35 consists of a grout delivery hose 351 and a connector 352; wherein, the connector 352 is a rotary joint, used to achieve a reliable connection between the grout delivery hose 351 and the rotatable jet grouting pipe 41, which ensures the sealing of the cement grout during the delivery process, while allowing the jet grouting pipe 41 to rotate freely, ensuring the continuity and stability of the jet grouting construction; the connector 352... 52 includes a connector housing 3521, a connector mandrel 3522 rotatably disposed within the housing, a retaining ring 3523, a bearing 3524, a sealing ring 3525, a jet grouting pipe connector 3526, and a slurry delivery hose connector 3527; wherein, the connector mandrel 3522 is supported within the connector housing 3521 by the bearing 3524 and is axially positioned by the retaining ring 3523; the sealing ring 3525 is disposed between the connector mandrel 3522 and the connector housing 3521 to realize dynamic control of high-pressure slurry. The system is sealed; the high-pressure hose connector 3527 is used to connect the high-pressure hose 351 of the grout delivery pipeline 35, and the jet grouting pipe connector 3526 is fixedly connected to the jet grouting pipe 41, so as to achieve continuous and leak-free delivery of grout during the rotation of the jet grouting pipe 41. The above-mentioned grout preparation and delivery system 3 has a reasonable structure and stable operation, which can effectively ensure the uniformity of grout, the continuity of grout supply and the flexibility of the rotation of the jet grouting pipe 41 during the jet grouting process, and provide a reliable guarantee for the formation of cement-soil piles with uniform quality and regular diameter.

[0029] The control system 5 includes a sensor module 51, a control terminal 52, and a controller module 53. The sensor module 51 includes a pressure sensor, a flow meter, a speed sensor, a depth sensor, and a data acquisition device, used to monitor construction parameters such as grouting pressure, cement slurry flow rate, rotation speed, lifting speed, and depth in real time. The control terminal 52 receives the monitoring data from the sensor module 51, stores, displays, and processes the monitored data, adjusts the construction parameters according to the design parameters, and sends instructions to the controller module 53. The controller module 53 controls the drilling system 1, the slurry preparation and delivery system 3, and the grouting and rebar installation system 4, achieving precise control over the grouting pressure, rotation speed, lifting speed, and the timing of the implantation of the reinforcing material 6, ensuring stable construction quality.

[0030] The grouting and rebar installation system 4 includes a jet grouting pipe 41 and a clamp 43. Both the jet grouting pipe 41 and the clamp 43 are connected to the grout preparation and delivery system 3. The clamp 43 is installed on the connector 352 and is electrically controlled to clamp and release. The clamp 43 clamps the upper end of the reinforcing material 6, which can fix the reinforcing material 6 in the middle of the jet grouting pipe 41 during the lowering process. When the jet grouting construction begins, the reinforcing material 6 is detached from the jet grouting pipe 41. The jet grouting pipe 41 includes an outer pipe 411 and an inner pipe 412. The interior of the inner pipe 412 is used to place the reinforcing material 6. Two nozzles 42 arranged horizontally at 120° are installed on the outer periphery of the outer pipe 411 near the bottom. The nozzles 42 include an integrated hemispherical part 42. 1 and bolt body 422, bolt body 422 is threadedly connected to external pipe 411. Both hemisphere 421 and bolt body 422 are provided with interconnected spray channels 423, and the spray angle of the opening of the spray channel 423 is obtuse relative to the radial direction of the rotary jet pipe 41. The top of the hemisphere 421 is provided with a groove on the same axis as the nozzle outlet direction, which facilitates the installation and adjustment of the position of the two nozzle outlets. After the two nozzles are installed, the two nozzles can be adjusted so that their nozzle outlet axes intersect on the same plane. When spraying cement grout, a spray energy convergence zone can be formed. By setting the intersection point of the nozzle outlet axes at the position where the design pile diameter is reduced by 50mm, it is possible to achieve low-pressure rotary jet grouting without weakening the ability to cut the soil, and it is easier to control the construction quality of the pile diameter.

[0031] Specifically, the internal pipe 412 is located inside the external pipe 411, and a gap is formed between the internal pipe 412 and the external pipe 411. This gap serves as a cement slurry delivery channel. Gaskets 413 are provided on the end faces of the external pipe 411 and the internal pipe 412. The gaskets 413 are connected to the external pipe 411 and the internal pipe 412 respectively by sealing bolts. While connecting the external pipe 411 and the internal pipe 412, the gaskets 413 also ensure the stability of the cement slurry pressure inside the jet grouting pipe 41.

[0032] Although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0033] Therefore, the above description is only a preferred embodiment of this application and is not intended to limit the scope of this application; that is, all equivalent modifications made in accordance with the scope of the claims of this application shall be within the protection scope of the claims of this application.

Claims

1. A low-pressure jet grouting and rebar-integrated foundation reinforcement method, characterized in that, Includes the following steps: S1. Use a drilling rig to drill holes at the pre-set pile positions; S2. Use a grouting and rebar installation system to perform simultaneous low-pressure jet grouting and rebar installation at the completed pile locations. S3. After completing the low-pressure jet grouting and rebar installation, the reinforcing material at the top of the pile is repaired and protected, and the jet grouting pile body is cured at the same time.

2. The low-pressure jet grouting and rebar-integrated foundation reinforcement method according to claim 1, characterized in that, Before drilling in step S1, the grout used for jet grouting and the reinforcing material for the pile body need to be pretreated.

3. The low-pressure jet grouting and rebar-integrated foundation reinforcement method according to claim 2, characterized in that, When preparing reinforcement materials, corrosion-resistant FRP fiber reinforcement is used in areas with abundant groundwater, and the surface is roughened by sandblasting; while in high-load scenarios, ribbed steel bars are used and rust-proofing treatment is applied.

4. The low-pressure jet grouting and rebar-integrated foundation reinforcement method according to claim 1, characterized in that, In step S2, during the low-pressure rotary jet grouting process, the grouting pressure, grouting flow rate, rotation speed, and lifting speed are monitored and recorded in real time.

5. The low-pressure jet grouting and rebar-integrated foundation reinforcement method according to claim 1, characterized in that, Step S2 specifically includes the following steps: S21. Place the reinforcing material into the spray nozzle using a clamp, ensuring that the lower end of the reinforcing material is in contact with the lower end of the spray nozzle. S22. Lower the jet grouting pipe containing the reinforcing material to the bottom of the borehole; S23. Depending on the geological type, inject cement grout into the borehole at a preset grouting pressure. S24. Based on the geological type, operate at the preset rotary nozzle rotation speed and lifting speed; S25: After the jet grouting pipe starts jet grouting and rises to the preset height, the clamp is released, so that the reinforcing material is separated from the jet grouting pipe. The reinforcing material stops rising with the jet grouting pipe and remains in the jet grouting pile body.

6. The low-pressure jet grouting and rebar-integrated foundation reinforcement method according to claim 5, characterized in that, In step S23, for clay formations, the grouting pressure of the cement grout is 5-12 MPa; while for sandy formations, the grouting pressure of the cement grout is 12-15 MPa.

7. The low-pressure jet grouting and rebar-integrated foundation reinforcement method according to claim 5, characterized in that, In step S24, for clay formations, the rotation speed of the jet nozzle is 10-20 rpm and the lifting speed is 15-25 cm / min; for sandy formations, the rotation speed of the jet nozzle is 20-35 rpm and the lifting speed is 8-15 cm / min.

8. A low-pressure jet grouting integrated foundation reinforcement system, characterized in that, Includes drilling rig system, rebar processing system, grout preparation and delivery system, grouting and rebar installation system, and control system: Drilling rig system, used for drilling operations on the foundation; A reinforcement processing system is used to pre-treat reinforcement materials implanted in the foundation; A grout preparation and delivery system is used to prepare grouting grout and deliver it to the grouting operation point. The grouting and rebar installation system is used to achieve simultaneous low-pressure jet grouting and reinforcement material implantation during construction. The control system is used to coordinate and control the operating parameters and work processes of each system, and is connected to the drilling rig system, grout preparation and delivery system and grouting and rebar installation system respectively.

9. The low-pressure jet grouting and rebar-integrated foundation reinforcement system according to claim 8, characterized in that, The grouting and rebar installation system includes a jet grouting pipe and a clamp, which are connected to a grout preparation and delivery system. The jet grouting pipe includes an internal pipe and an external pipe, which are connected by a gasket at its bottom. Two nozzles arranged horizontally at 120° are installed on the outer periphery of the external pipe near the bottom.

10. The low-pressure jet grouting and rebar-integrated foundation reinforcement system according to claim 9, characterized in that, The nozzle comprises an integrally formed hemisphere and a bolt body. The bolt body is threadedly connected to an external pipe. Both the hemisphere and the bolt body have interconnected spray channels, with one end of the spray channel open. The spray angle is obtuse to the radial direction of the swirl nozzle. The end of the hemisphere away from the bolt body has a groove on the same axis as the nozzle outlet direction.

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