Pneumatic bidirectional stirring and jet grouting pile forming device and pile forming method

Abstract

The application discloses a kind of pneumatic bidirectional stirring jet grouting pile-forming device and pile-forming method, belong to jet grouting pile-forming technical field, wherein pneumatic bidirectional stirring jet grouting pile-forming device includes rack, lifting frame, outer drill cylinder and inner drill cylinder, outer drill cylinder is sleeved on inner drill cylinder, inner drill cylinder bottom end is located outside outer drill cylinder, and is provided with drill bit;Between outer drill cylinder and inner drill cylinder, there is grouting passage, outer drill cylinder side wall has the jet grouting hole being communicated with grouting passage, inner drill cylinder is used to be communicated with external gas conveying equipment, after outer drill cylinder and inner drill cylinder relatively rotate, jet orifice can be intermittently communicated with jet grouting hole and be correspondingly communicated and jet grouting hole is jetted and blown airflow, to prevent jet grouting hole from being blocked.The pneumatic bidirectional stirring jet grouting pile-forming device provided by the application realizes the intermittent communication of jet orifice and jet grouting hole and jet grouting airflow by the relative rotation of outer drill cylinder and inner drill cylinder, solves the problem that jet grouting hole is easily blocked under the condition of high cohesive force soil, makes the jet grouting hole of stirring machine keep unobstructed, realizes the continuous jetting of cement paste.

Description

Technical Field

[0001] This invention belongs to the field of shotcrete pile technology, specifically relating to a pneumatic bidirectional mixing shotcrete pile forming device and pile forming method. Background Technology

[0002] In modern construction engineering, foundation treatment is a crucial step in ensuring the stability and safety of buildings. This is especially true in soft soil foundation areas, where the poor mechanical properties of soft soil cannot directly meet the load-bearing requirements of buildings. Therefore, various foundation treatment technologies have emerged, among which cement-mixed pile technology has been widely used in soft soil foundation treatment. By mixing cement with soft soil, cement-mixed piles with a certain strength and stability are formed, thereby improving the bearing capacity of the foundation, mitigating its deformation characteristics, and providing reliable support for the superstructure.

[0003] The core working principle of cement mixing pile construction is to use mixing machinery to force cement, acting as a curing agent, to be mixed with soft soil deep underground. In specific operation, the mixing machinery needs to be lowered to a predetermined depth below the ground surface, and cement slurry is injected into the soft soil through the internal grouting channel. At the same time, the mixing blades rotate to fully mix the cement slurry with the soft soil, forming a uniform mixture. After a certain period of time, the mixture hardens to form a cement mixing pile.

[0004] Under certain specific working conditions, such as when the soil has high cohesion, soil particles tend to adhere to each other. Soil particles around the grouting hole may accumulate around the grouting hole under the action of cohesion, gradually accumulating and blocking the grouting hole, affecting the normal spraying of cement grout, resulting in insufficient mixing of soft soil and cement, reducing the quality of cement mixing piles and the foundation reinforcement effect.

[0005] In conclusion, developing a pneumatic bidirectional mixing jet grouting pile-forming device that can effectively solve the problem of grout hole blockage and improve construction efficiency is of great practical significance and plays a key role in promoting the development of foundation treatment technology and ensuring the quality of building projects. Summary of the Invention

[0006] The purpose of this invention is to provide a pneumatic bidirectional mixing and spraying pile forming device and a pile forming method, so as to keep the spraying holes of the mixing machinery unobstructed and realize the continuous spraying of cement slurry.

[0007] According to one aspect, in order to achieve the above objectives, embodiments of the present invention provide a pneumatic bidirectional mixing and spraying pile forming device, including a frame, a lifting frame, an outer drill cylinder and an inner drill cylinder. The lifting frame is slidably mounted on the frame, and both the outer drill cylinder and the inner drill cylinder are rotatably mounted on the lifting frame. The outer drill cylinder is sleeved on the inner drill cylinder, and the bottom end of the inner drill cylinder is located outside the outer drill cylinder and is provided with a drill bit. Both the outer drill cylinder and the inner drill cylinder are provided with mixing blades. The outer drill tube and the inner drill tube have a grouting channel for communicating with external grouting equipment. The side wall of the outer drill tube has a grouting hole that communicates with the grouting channel. The inner drill tube is used to communicate with external air supply equipment. The side wall of the inner drill tube has an air jet hole. After the outer drill tube and the inner drill tube rotate relative to each other, the air jet hole can intermittently communicate with the grouting hole and spray airflow into the grouting hole to prevent the grouting hole from being blocked.

[0008] In one possible implementation, a connecting ring is provided inside the outer drill barrel, the connecting ring contacts the outer wall of the inner drill barrel, and the connecting ring has a connecting hole corresponding to the radial position of the grouting hole. After the outer drill barrel and the inner drill barrel rotate relative to each other, the connecting hole can intermittently communicate with the air jet hole, so that the air jet hole intermittently communicates with the grouting hole.

[0009] In one possible implementation, the lifting frame is provided with a central cylinder, and an outer cylinder rotating sleeve and an inner cylinder rotating sleeve are rotatably disposed on the central cylinder. The outer drill cylinder is disposed on the outer cylinder rotating sleeve, and the inner drill cylinder is disposed on the inner cylinder rotating sleeve.

[0010] In one possible implementation, an outer cylinder bevel gear is coaxially mounted on the outer cylinder rotating sleeve, an inner cylinder bevel gear is coaxially mounted on the inner cylinder rotating sleeve, and a reversing bevel gear is rotatably mounted on the central cylinder. The axis of the reversing bevel gear is perpendicular to the axes of the outer cylinder bevel gear and the inner cylinder bevel gear, and meshes with both the outer cylinder bevel gear and the inner cylinder bevel gear. The outer cylinder rotating sleeve is used to drive the outer drill barrel and the inner drill barrel to rotate in opposite directions by means of the reversing bevel gear.

[0011] In one possible implementation, the outer drill barrel is slidably disposed on the outer barrel rotating sleeve, and the air jet has an open state and a closed state; In the open state, the connecting ring can slide to a position corresponding to the axial position of the jet hole under the drive of the outer drill barrel, so that the jet hole can intermittently spray airflow to the slurry hole; In the closed state, the connecting ring can slide under the drive of the outer drill barrel to a position offset from the axial position of the air jet, so that the air jet is blocked.

[0012] In one possible implementation, the outer drill barrel sidewall has a plurality of grouting holes communicating with the grouting channel, and the outer drill barrel sidewall is rotatably provided with a grouting rotating sleeve for communicating with external grouting equipment and communicating with the grouting holes, the grouting rotating sleeve being used to continuously supply grout when the outer drill barrel rotates.

[0013] In one possible implementation, the sidewall of the central cylinder is connected to an injection pipe for connecting to an external gas supply device, and the central cylinder is in communication with the inner drill tube for supplying gas to the inner drill tube.

[0014] In one possible implementation, the top of the central cylinder is detachably provided with an end cap. After the end cap is opened, a core pile can be inserted into the inner drill barrel from the top of the central cylinder. The inner wall of the inner drill barrel is provided with at least two rings of guide rods arranged axially. The guide rods are used to contact the core pile to ensure the coaxiality of the core pile and the inner drill barrel. The bottom end of the drill bit is open and is provided with a one-way opening mechanism that can only be opened outward. After the one-way opening mechanism is opened, the core pile in the inner drill barrel can be released into the pile body.

[0015] In one possible implementation, the one-way opening mechanism includes a limiting ring and a sealing flap. The limiting ring is disposed on the inner wall of the drill bit, and the sealing flap is oscillatingly disposed on the side of the limiting ring near the bottom opening of the drill bit. A torsion spring is disposed between the sealing flap and the limiting ring, and the torsion spring is used to provide a force for the sealing flap to approach the limiting ring. There are multiple sealing flaps distributed circumferentially along the limiting ring. After the multiple sealing flaps oscillate, they can block or open the bottom opening of the drill bit.

[0016] This invention also provides a pneumatic bidirectional mixing and jet grouting pile forming method, which uses the aforementioned pneumatic bidirectional mixing and jet grouting pile forming device and includes the following steps: First, pre-mixing and sinking are carried out. The outer and inner drill cylinders are rotated and sinked. After the drill bit sinks to the preset depth, grouting starts from the bottom of the pile. The grouting time at the bottom of the pile is more than 30 seconds. Then, the outer and inner drill cylinders are lifted. After being lifted to the preset position, grouting is continuously sprayed for more than 30 seconds. Then, the grouting and mixing are repeated several times. During the final grouting and mixing, the air jet is switched to the closed state. After the drill bit sinks to the bottom of the pile, the end cap at the top of the central cylinder is opened and the core pile is inserted. The core pile will be left inside the pile during the subsequent lifting of the outer and inner drill cylinders. After the pile solidifies, it will be combined with the pile body and serve as a reinforcing component of the pile body.

[0017] The significant technical advantage of this invention lies in the design of intermittently connecting the jet vent and the grouting hole through the relative rotation of the outer and inner drill cylinders, and injecting airflow into the grouting hole. This design solves the problem of easy clogging of the grouting hole in high-cohesion soil conditions, ensuring the grouting hole remains unobstructed and enabling continuous injection of cement grout. The airflow can promptly disperse soil particles accumulated around the grouting hole, ensuring normal injection of cement grout, ensuring thorough mixing of soft soil and cement, improving the quality of cement mixing piles and the foundation reinforcement effect, and enabling continuous and stable construction. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the structure of a pneumatic bidirectional mixing and spraying pile forming device in one embodiment of the present invention; Figure 2 for Figure 1 Schematic diagram of the structure of the outer and inner drill pipes; Figure 3 for Figure 2 Enlarged view of point A in the middle; Figure 4 for Figure 2 Enlarged view at point B in the middle; Figure 5 for Figure 2 Enlarged view at point C; Figure 6 for Figure 1 A schematic diagram of the structure of the bottom surface of the middle limiting ring.

[0020] In the diagram: 1. Frame, 2. Lifting frame, 3. Outer drill cylinder, 4. Inner drill cylinder, 5. Drill bit, 6. Mixing blade, 7. Grouting channel, 301. Spray hole, 401. Air jet hole, 302. Connecting ring, 303. Connecting hole, 8. Central cylinder, 9. Outer cylinder rotating sleeve, 10. Inner cylinder rotating sleeve, 11. Outer cylinder bevel gear, 12. Inner cylinder bevel gear, 13. Reversing bevel gear, 304. Grouting hole, 14. Grouting rotating sleeve, 15. Air injection pipe, 16. End cap, 17. Guide rod, 18. One-way opening mechanism, 1801. Limiting ring, 1802. Sealing flap. Detailed Implementation

[0021] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0023] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0024] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0025] In the description of the embodiments of this application, the term "and / or" is merely a description of the association relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship. In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple groups" refers to two or more groups (including two groups), and "multiple pieces" refers to two or more pieces (including two pieces).

[0026] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" 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 the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0027] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation", "connection", "linking", and "fixing" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components.

[0028] Please see Figures 1-6This invention illustrates a pneumatic bidirectional mixing and spraying pile-forming device according to an embodiment of the present invention, including a frame 1, a lifting frame 2, an outer drill cylinder 3, and an inner drill cylinder 4. The frame 1 serves as the basic support structure for the entire device. The lifting frame 2 has a lifting and sliding structure mounted on the frame 1, enabling the lifting frame 2 to move vertically up and down on the frame 1. The lifting of the lifting frame 2 drives the outer drill cylinder 3 and the inner drill cylinder 4 to a predetermined construction depth below ground level.

[0029] Both the outer drill barrel 3 and the inner drill barrel 4 are rotatably mounted on the lifting frame 2. The outer drill barrel 3 is fitted onto the inner drill barrel 4, and the bottom end of the inner drill barrel 4 extends beyond the outer drill barrel 3 and is equipped with a drill bit 5. The drill bit 5 is conical to facilitate easier cutting into the soil and reduce resistance during drilling. Both the outer drill barrel 3 and the inner drill barrel 4 are equipped with mixing blades 6 spaced axially to uniformly mix the soft soil and cement slurry.

[0030] A grouting channel 7 is formed between the outer drill barrel 3 and the inner drill barrel 4 for communication with external grouting equipment. The external grouting equipment (such as a mud pump) delivers cement grout into the grouting channel 7 through a pipeline. The side wall at the bottom of the outer drill barrel 3 is provided with grouting holes 301 that communicate with the grouting channel 7. Cement grout is sprayed into the surrounding soft soil through these grouting holes 301.

[0031] The inner drill barrel 4 is used to connect with external air supply equipment (such as an air compressor). An air jet hole 401 is provided on the side wall at the bottom end of the inner drill barrel 4. The outer drill barrel 3 and the inner drill barrel 4 can rotate relative to each other during operation, so that the air jet hole 401 can intermittently connect with the grouting hole 301. When the air jet hole 401 connects with the grouting hole 301, the high-pressure gas delivered by the external air supply equipment to the inner drill barrel 4 is blown into the grouting hole 301 through the air jet hole 401. The instantaneous pressure of the airflow can disperse the soil particles gathered around the grouting hole 301, preventing the soil particles from accumulating and clogging the grouting hole 301 due to cohesion, thereby ensuring that the cement grout can be continuously and normally ejected from the grouting hole 301.

[0032] During operation, the equipment is first moved to the construction position, and then the lifting frame 2 is activated, causing the outer drill barrel 3 and the inner drill barrel 4 to gradually descend to the predetermined depth below the ground under the action of the drill bit 5. During the drilling process, the mixing blades 6 on the outer drill barrel 3 and the inner drill barrel 4 perform preliminary mixing of the surrounding soft soil, making the soil structure loose and preparing for subsequent grouting and mixing.

[0033] Once the predetermined depth is reached, the external grouting equipment is activated, and cement grout is injected into the soft soil through the grouting channel 7 from the grouting hole 301. Simultaneously, the outer drill cylinder 3 and inner drill cylinder 4 rotate continuously, and the mixing blades 6 thoroughly mix the injected cement grout with the soft soil, forming a homogeneous mixture. During this process, the outer drill cylinder 3 and inner drill cylinder 4 rotate relative to each other, and the air jet 401 intermittently connects with the grouting hole 301, periodically blowing air into the grouting hole 301 to ensure it remains unobstructed, allowing the cement grout to be injected stably and ensuring thorough mixing of the soft soil and cement. Subsequently, the lifting frame 2 slowly raises the outer drill cylinder 3 and inner drill cylinder 4, continuing grouting during the raising process. The mixing blades 6 continuously stir the mixture, ensuring the cement grout is mixed with the soft soil, until the outer drill cylinder 3 and inner drill cylinder 4 are raised to the preset position.

[0034] The intermittent connection between the jet vent 401 and the grouting vent 301, achieved by the relative rotation of the outer drill barrel 3 and the inner drill barrel 4, and the design of blowing air into the grouting vent 301, solves the problem of easy clogging of the grouting vent 301 in high-cohesion soil conditions. This ensures that the grouting vent 301 remains unobstructed, enabling continuous ejection of cement grout. The airflow can promptly disperse soil particles accumulated around the grouting vent 301, ensuring normal ejection of cement grout, ensuring thorough mixing of soft soil and cement, improving the quality of cement mixing piles and the foundation reinforcement effect, and enabling continuous and stable construction.

[0035] Please see Figure 2 and Figure 4 In some embodiments, a connecting ring 302 is provided inside the outer drill barrel 3 near the bottom. The inner diameter of the connecting ring 302 is adapted to the outer wall size of the inner drill barrel 4, allowing them to make close contact. The connecting ring 302 is provided with connecting holes 303, the radial positions of which correspond one-to-one with the grouting holes 301 on the outer drill barrel 3. That is, from the top view of the outer drill barrel 3, the grouting holes 301 on the outer drill barrel 3 and the connecting holes 303 on the connecting ring 302 are at the same radial position.

[0036] During operation, gas cannot pass through when the jet hole 401 on the inner drill tube 4 is not aligned with the connecting hole 303 on the connecting ring 302. As the outer drill tube 3 and the inner drill tube 4 continue to rotate relative to each other, the jet hole 401, the connecting hole 303, and the grouting hole 301 are connected when they are in the same radial direction. The high-pressure gas supplied by the external gas supply equipment in the inner drill tube 4 quickly enters the grouting hole 301 through the jet hole 401 and the connecting hole 303, and is ejected in the form of an instantaneous airflow with high instantaneous pressure, which can disperse the soil particles that have accumulated around the grouting hole 301 due to soil cohesion. Subsequently, as the outer drill tube 3 and the inner drill tube 4 continue to rotate relative to each other, the jet hole 401 and the connecting hole 303 are misaligned, the channel is closed, and the gas stops ejecting until the three are aligned and connected again.

[0037] By periodically opening and closing the channel between the jet hole 401 and the grouting hole 301 using the relative rotation of the drill barrel, instantaneous airflow generation and spraying are cleverly achieved. The periodic spraying of the grouting hole 301 by the instantaneous airflow prevents the grouting hole 301 from being blocked by soil particles, ensuring that cement grout can be continuously and stably sprayed from the grouting hole 301, and guaranteeing thorough mixing of the soft soil and cement.

[0038] Please see Figure 2 and Figure 3 In some embodiments, a cylindrical central cylinder 8 is provided on the lifting frame 2, and an outer cylinder rotating sleeve 9 and an inner cylinder rotating sleeve 10 are rotatably provided on the central cylinder 8. The outer drill cylinder 3 is provided on the outer cylinder rotating sleeve 9, and the inner drill cylinder 4 is provided on the inner cylinder rotating sleeve 10, so that the outer drill cylinder 3 and the inner drill cylinder 4 can rotate with the outer cylinder rotating sleeve 9 and the inner cylinder rotating sleeve 10 respectively.

[0039] An outer cylinder bevel gear 11 is coaxially mounted on the outer cylinder rotating sleeve 9, and an inner cylinder bevel gear 12 is similarly coaxially mounted on the inner cylinder rotating sleeve 10. A reversing bevel gear 13 is rotatably mounted on the central cylinder 8, with its axis perpendicular to the axes of the outer cylinder bevel gear 11 and the inner cylinder bevel gear 12. The upper and lower sides of the reversing bevel gear 13 mesh with the outer cylinder bevel gear 11 and the inner cylinder bevel gear 12, respectively, forming a gear transmission structure. The outer cylinder rotating sleeve 9 is connected to an external drive device, which can be a motor, hydraulic motor, or other power equipment, providing power to the entire rotating system.

[0040] During operation, the external drive device is activated. When the external drive device drives the outer cylinder rotating sleeve 9 to rotate, the outer cylinder bevel gear 11 on the outer cylinder rotating sleeve 9 rotates accordingly. The outer cylinder bevel gear 11 drives the reversing bevel gear 13 to rotate. Because the axis of the reversing bevel gear 13 is perpendicular to the axes of the outer cylinder bevel gear 11 and the inner cylinder bevel gear 12, the reversing bevel gear 13 can drive the inner cylinder bevel gear 12 to rotate in the opposite direction, thereby converting the same power source into the opposite rotation of the outer drill barrel 3 and the inner drill barrel 4.

[0041] In the construction of silt layers in soft soil foundations, this reverse rotation allows the mixing blades 6 to mix the silt from different directions. This avoids the problem of the soil being pushed in a fixed direction and forming undisturbed "dead corners" as in traditional unidirectional mixing methods. This ensures the silt is fully disturbed, solving the problem that the silt, due to its strong agglomeration and poor fluidity, cannot fill the mixing gaps on its own. Simultaneously, the reverse rotation increases the diversity of mechanical shearing, improves the diffusion efficiency of cement slurry, and makes the mixing of soil and cement slurry more uniform, thereby ensuring the compactness of the pile and improving the quality of pile formation.

[0042] Please see Figure 2 and Figure 3In some embodiments, the outer cylinder rotating sleeve 9 is provided with several guide rods in a direction parallel to the axial direction. The guide rods pass through the outer drill barrel 3 and serve a guiding function. At the same time, a drive screw is also rotatably provided on the outer cylinder rotating sleeve 9. The drive screw is threadedly connected to the outer drill barrel 3 and is used to drive the outer drill barrel 3 to slide. After the outer drill barrel 3 slides to the target position, conventional positioning structures such as bolts can be used to fix the outer drill barrel 3.

[0043] In this embodiment, the jet vent 401 has an open state and a closed state. In the early stages of construction, due to the high cohesion of the soft soil, the jet vent 301 is prone to blockage. At this time, it is necessary to open the jet vent 401. The locking device is used to release the outer drill cylinder 3, allowing it to slide axially along the outer cylinder rotating sleeve 9, thus moving the connecting ring 302 to a position corresponding to the axial position of the jet vent 401. At this time, as the outer drill cylinder 3 and the inner drill cylinder 4 rotate relative to each other, the connecting hole 303 on the connecting ring 302 can intermittently connect with the jet vent 401, thereby enabling the jet vent 401 to intermittently jet airflow into the jet vent 301, preventing blockage.

[0044] During pile construction, to ensure pile strength, repeated grouting and mixing are typically performed. During the final grouting and mixing, considering that the pile uniformity is already good and the cohesion of the soft soil is reduced, the risk of clogging the grouting hole 301 is low, so the air jet hole 401 can be switched to the closed state. By operating the locking device, the outer drill barrel 3 slides, causing the connecting ring 302 to move and offset from the axial position of the air jet hole 401. In this way, even if the outer drill barrel 3 and the inner drill barrel 4 rotate relative to each other, the air jet hole 401 is blocked by the connecting ring 302 and cannot release air. If air bubbles remain in the pile, the mixing action during the final grouting process can allow any remaining air bubbles to escape, preventing them from affecting the pile quality.

[0045] Please see Figure 2 In some embodiments, a plurality of grouting holes 304 communicating with the grouting channel 7 are evenly distributed on the side wall of the outer drill barrel 3. The grouting rotating sleeve 14 is rotatably mounted on the side wall of the outer drill barrel 3 and communicates with the grouting holes 304. The grouting rotating sleeve 14 is connected to an external grouting device (such as a mud pump) through a pipeline, thereby realizing the continuous delivery of cement grout to the grouting rotating sleeve 14. In actual construction, when the outer drill barrel 3 rotates, the grouting rotating sleeve 14 may not rotate with it, thereby continuously injecting cement grout into the grouting channel 7. At the same time, in order to ensure the stability of the grouting rotating sleeve 14 when the outer drill barrel 3 rotates, an extension frame (not shown in the figure) extending in the direction of the lifting frame 2 can be designed on the grouting rotating sleeve 14, and the extension frame is fixed to the lifting frame 2 using conventional fixing methods (such as bolt fixing) to ensure the stability of the grouting rotating sleeve 14.

[0046] An air injection pipe 15 is connected to the side wall of the central cylinder 8. One end of the air injection pipe 15 is connected to an external air supply device (such as an air compressor), and the other end is connected to the inside of the central cylinder 8. The air injection pipe 15 is connected to the central cylinder 8. When the external air supply device is started, the gas can enter the central cylinder 8 through the air injection pipe 15 and then enter the inner drill tube 4, ensuring that the inner drill tube 4 receives a stable gas supply.

[0047] Please see Figure 2 , 5 6. In some embodiments, a removable end cap 16 is designed at the top of the central cylinder 8. When it is necessary to insert the core pile, the operator can remove the end cap 16 from the top of the central cylinder 8. The internal space of the central cylinder 8 is connected to the inner drill cylinder 4, and the core pile can be inserted into the inner drill cylinder 4. The inner wall of the inner drill cylinder 4 is provided with at least two rings of guide rods 17 arranged axially.

[0048] The one-way opening mechanism 18 includes a limiting ring 1801 and sealing flaps 1802. The bottom end of the drill bit 5 is designed as an open structure, and a limiting ring 1801 is provided on the inner wall of the drill bit 5. The inner diameter of the limiting ring 1801 is slightly larger than the outer diameter of the core pile. On the side of the limiting ring 1801 near the opening at the bottom end of the drill bit 5, multiple sealing flaps 1802 are oscillatingly arranged by a pin. The sealing flaps 1802 are evenly distributed circumferentially along the limiting ring 1801. A torsion spring is provided between each sealing flap 1802 and the limiting ring 1801 to provide a force to the sealing flap 1802 to approach the limiting ring 1801, so that the sealing flap 1802 can fit against the bottom surface of the limiting ring 1801 when no external force is applied, thereby sealing the opening at the bottom end of the drill bit 5. A rubber seal can be provided between adjacent sealing flaps 1802 to enhance the sealing effect and prevent soil from entering the inner drill cylinder 4.

[0049] During the construction of cement mixing piles, the initial shotcrete mixing operation is carried out normally. At this time, the end cap 16 seals the top of the central cylinder 8, the air injection pipe 15 supplies air to the inner drill cylinder 4, and the air jet hole 401 sprays out pulsed airflow to prevent the shotcrete hole 301 from being blocked. During this process, the sealing flap 1802 seals the bottom opening of the drill bit 5 to prevent soil from entering the inner drill cylinder 4.

[0050] During the final grouting and mixing, the jet vent 401 is switched to the closed state, and the outer drill barrel 3 and inner drill barrel 4 descend to the bottom of the pile. At this time, the operator can open the end cap 16 at the top of the central cylinder 8 and insert the core pile from the top of the central cylinder 8. The core pile slides down inside the inner drill barrel 4, and the guide rod 17 contacts the surface of the core pile, ensuring that the core pile descends along the central axis of the inner drill barrel 4. When the bottom end of the core pile reaches the one-way opening mechanism 18 at the bottom end of the drill bit 5, the bottom end of the core pile presses against the sealing flap 1802, overcoming the torsion spring force, causing the sealing flap 1802 to open downwards, and the core pile protrudes from the opening at the bottom end of the drill bit 5 and enters the pile body. Subsequently, the outer drill barrel 3 and inner drill barrel 4 begin to rise, leaving the core pile inside the pile body. After the core pile has completely passed through the limit ring 1801, the sealing flap 1802 automatically returns to the sealing state under the action of the torsion spring. After the pile body solidifies, the core pile combines with the pile body, which can improve the strength of the pile body.

[0051] This embodiment also provides a pneumatic bidirectional mixing and spraying method for pile formation, which uses the above-mentioned pneumatic bidirectional mixing and spraying device for pile formation.

[0052] During construction, pre-mixing and sinking are carried out first. The outer drill barrel 3 and the inner drill barrel 4 are rotated and sunk at a speed of 30~50 rpm. The drilling speed should be less than 0.8 m / min. After the drill bit 5 sinks to the preset depth, grouting starts from the bottom of the pile. The grouting time at the bottom of the pile should be maintained at more than 30 seconds. Then, the outer drill barrel 3 and the inner drill barrel 4 are lifted. After being lifted to the preset position, grouting is continuously sprayed for more than 30 seconds. Then, the grouting and mixing are repeated several times as needed.

[0053] During the above process, the jet hole 401 is periodically connected to the connecting hole 303 and the grouting hole 301. The grouting hole 301 is periodically sprayed by the instantaneous airflow to prevent the grouting hole 301 from being blocked by soil particles, and to ensure that the cement grout can be continuously and stably sprayed out from the grouting hole 301.

[0054] During the final grouting and mixing, the jet vent 401 is switched to the closed state. After the drill bit 5 sinks to the bottom of the pile, the end cap 16 at the top of the central cylinder 8 is opened and the core pile is inserted. The core pile will be left inside the pile during the subsequent lifting process of the outer drill cylinder 3 and the inner drill cylinder 4. After the pile solidifies, it will be combined with the pile body and serve as a stiffening component of the pile body to improve the structural strength of the pile body.

[0055] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of protection of the claims of the present invention.

Claims

1. A pneumatic bidirectional mixing and spraying grouting pile forming device, characterized in that, The machine includes a frame (1), a lifting frame (2), an outer drill cylinder (3), and an inner drill cylinder (4). The lifting frame (2) is slidably mounted on the frame (1). The outer drill cylinder (3) and the inner drill cylinder (4) are both rotatably mounted on the lifting frame (2). The outer drill cylinder (3) is sleeved on the outer periphery of the inner drill cylinder (4). The lower end of the inner drill cylinder (4) penetrates the bottom wall of the outer drill cylinder (3), and a drill bit (5) is provided at the lower end of the inner drill cylinder (4). A stirring blade (6) is provided on both the outer drill cylinder (3) and the inner drill cylinder (4). There is a grouting channel (7) between the outer drill barrel (3) and the inner drill barrel (4) for communicating with external grouting equipment. The side wall of the outer drill barrel (3) has a grouting hole (301) communicating with the grouting channel (7). The inner drill barrel (4) is used to communicate with external air supply equipment. The side wall of the inner drill barrel (4) has an air jet hole (401). After the outer drill barrel (3) and the inner drill barrel (4) rotate relative to each other, the air jet hole (401) can intermittently communicate with the grouting hole (301) and blow airflow into the grouting hole (301) to prevent the grouting hole (301) from being blocked. A connecting ring (302) is provided inside the outer drill barrel (3). The connecting ring (302) is sleeved on the outer periphery of the inner drill barrel (4). The connecting ring (302) has a connecting hole (303) corresponding to the radial position of the slurry hole (301). After the outer drill barrel (3) and the inner drill barrel (4) rotate relative to each other, the connecting hole (303) can intermittently communicate with the air jet hole (401) so that the air jet hole (401) intermittently communicates with the slurry hole (301). The lifting frame (2) is provided with a central cylinder (8), and an outer cylinder rotating sleeve (9) and an inner cylinder rotating sleeve (10) are rotatably provided on the central cylinder (8). The outer drill cylinder (3) is connected to the outer periphery of the outer cylinder rotating sleeve (9), and the inner drill cylinder (4) is connected to the outer periphery of the inner cylinder rotating sleeve (10). The outer drill barrel (3) is slidably disposed on the outer barrel rotating sleeve (9) to allow the jet hole (401) to have an open state and a closed state; In the open state, the connecting ring (302) can slide under the drive of the outer drill barrel (3) to be axially aligned with the jet hole (401), so that the jet hole (401) can intermittently spray airflow onto the slurry hole (301); In the closed state, the connecting ring (302) can slide under the drive of the outer drill barrel (3) to be axially offset from the jet hole (401) so that the jet hole (401) is blocked.

2. The pneumatic bidirectional mixing and spraying grouting pile forming device according to claim 1, characterized in that, An outer cylinder bevel gear (11) is coaxially arranged on the outer cylinder rotating sleeve (9), an inner cylinder bevel gear (12) is coaxially arranged on the inner cylinder rotating sleeve (10), and a reversing bevel gear (13) is rotatably arranged on the central cylinder (8). The axis of the reversing bevel gear (13) is perpendicular to the axes of the outer cylinder bevel gear (11) and the inner cylinder bevel gear (12), and meshes with both the outer cylinder bevel gear (11) and the inner cylinder bevel gear (12). The outer cylinder rotating sleeve (9) is used to drive the outer drill barrel (3) and the inner drill barrel (4) to rotate in opposite directions by means of the reversing bevel gear (13).

3. The pneumatic bidirectional mixing and spraying grouting pile forming device according to claim 1, characterized in that, The outer drill barrel (3) has several grouting holes (304) on its side wall that communicate with the grouting channel (7). The outer drill barrel (3) is fitted with a grouting rotating sleeve (14) for communicating with external grouting equipment. The outer drill barrel (3) and the grouting rotating sleeve (14) are rotatably engaged. The grouting rotating sleeve (14) is used to continuously supply grout to the grouting channel (7) through the grouting holes (304) when the outer drill barrel (3) rotates.

4. The pneumatic bidirectional mixing and spraying grouting pile forming device according to claim 1, characterized in that, The side wall of the central cylinder (8) is connected to an air injection pipe (15) for connecting to an external air supply device. The central cylinder (8) is connected to the inner drill cylinder (4) for supplying air to the inner drill cylinder (4).

5. The pneumatic bidirectional mixing and spraying grouting pile forming device according to claim 4, characterized in that, The top of the central cylinder (8) is detachably provided with an end cap (16). After the end cap (16) is opened, the core pile can be inserted into the inner drill cylinder (4) from the top of the central cylinder (8). The inner wall of the inner drill cylinder (4) is provided with at least two rings of guide rods (17) arranged along the axial direction. The guide rods (17) extend radially along the inner drill cylinder (4). The extended end of the guide rods (17) is used to contact the core pile to ensure the coaxiality of the core pile and the inner drill cylinder (4). The lower end of the drill bit (5) is provided with a one-way opening mechanism (18) for opening downward. After the one-way opening mechanism (18) is opened, the core pile in the inner drill cylinder (4) can be released into the pile body.

6. The pneumatic bidirectional mixing and spraying grouting pile-forming device according to claim 5, characterized in that, The one-way opening mechanism (18) includes a limiting ring (1801) and a sealing flap (1802). The limiting ring (1801) is disposed on the inner wall of the drill bit (5). The sealing flap (1802) is swung and disposed below the limiting ring (1801). A torsion spring is disposed between the sealing flap (1802) and the limiting ring (1801). The torsion spring is used to provide the force for the sealing flap (1802) to swing upward and approach the limiting ring (1801). There are multiple sealing flaps (1802) and they are distributed circumferentially along the limiting ring (1801). After the multiple sealing flaps (1802) swing, they can block or open the lower opening of the drill bit (5).

7. A pneumatic bidirectional mixing and jet grouting pile forming method, using the pneumatic bidirectional mixing and jet grouting pile forming device according to any one of claims 1-6, characterized in that, Includes the following steps: First, pre-mixing and sinking are carried out. The outer drill cylinder (3) and the inner drill cylinder (4) are rotated and sinked. After the drill bit (5) sinks to the preset depth, grouting is started from the bottom of the pile. The grouting time at the bottom of the pile is more than 30 seconds. Then the outer drill cylinder (3) and the inner drill cylinder (4) are lifted. After being lifted to the preset position, grouting is continuously sprayed for more than 30 seconds. Then, the grouting and mixing are repeated several times. During the final grouting and mixing, the jet hole (401) is switched to the closed state. After the drill bit (5) sinks to the bottom of the pile, the end cap (16) at the top of the center cylinder (8) is opened and the core pile is inserted. The core pile will be left in the pile during the subsequent lifting process of the outer drill cylinder (3) and the inner drill cylinder (4). After the pile solidifies, it will be combined with the pile body as a stiffening component of the pile body.

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