A method for forming a uniform circular mixing pile

Abstract

This invention discloses a method for uniformly forming a circulating mixing pile, relating to the field of cement-soil mixing pile construction technology. The multi-stage three-dimensional mixing head includes a column, with a flange fixedly connected to the top of the column. A rotating seat is bolted to the top of the flange, and a first rotating pipe is rotatably connected inside the rotating seat. An internal hexagonal tube for easy installation is fixedly connected to the top outer wall of the first rotating pipe. In this invention, a three-stage continuous mixing system of "bottom forced dispersion – middle planar shearing – upper three-dimensional mixing" is formed by a dispersion plate, an upper forward-rotating mixing plate, and a self-rotating three-dimensional mixing component. This allows the cement slurry and soil to undergo at least three shearing mixtures in different directions at each depth, further reducing the pile strength dispersion coefficient and ensuring sufficient contact between the cement slurry and the broken soil particles, thus further improving the uniformity of the formed mixing pile.

Description

Technical Field

[0001] This invention relates to the field of cement-soil mixing pile construction technology, and more specifically, to a method for uniformly forming the pile body of a circulating mixing pile. Background Technology

[0002] Cement-soil mixing piles are one of the most widely used technologies in the reinforcement of soft soil foundations, and are widely used in engineering fields such as building foundations, roadbeds, foundation pit water-stop curtains, and slope protection.

[0003] Traditional cement-soil mixing piles mostly employ a single-axis, unidirectional mixing process, relying solely on single or double-layer axial blades for planar shear mixing. This results in limited mixing range and poor three-dimensional mixing effects. Cement slurry tends to concentrate in the central area of ​​the pile, with insufficient cement content at the edges, leading to a high coefficient of variation in pile strength and frequent quality problems such as pile breakage and diameter reduction. Simultaneously, traditional drill bits have weak soil-breaking capabilities, resulting in slow drilling speeds in complex soil layers such as hard clay and dense sand. Furthermore, the soil tends to rotate synchronously with the drill rod, causing a "drill-clamping" phenomenon, which not only significantly reduces construction efficiency but also leads to insufficient soil breaking, further affecting the uniformity of cement-soil mixing. In addition, the traditional single-jet nozzle design is prone to "hanging piles" with insufficient cement content at the pile bottom and slurry leakage along the outer wall of the drill rod, severely restricting the application of mixing pile technology under complex geological conditions. Therefore, a method for achieving uniform pile formation in cyclic mixing piles is urgently needed to solve these problems. Summary of the Invention

[0004] In view of the problems in related technologies, this invention proposes a method for uniform forming of circulating mixing piles to overcome the above-mentioned technical problems existing in the existing related technologies.

[0005] The technical solution of this invention is implemented as follows: A method for achieving uniform forming of circulating mixing piles, employing a multi-stage three-dimensional mixing head for construction, includes the following steps: S1: Level the construction site, remove ground and underground obstacles, measure and set out the pile positions, control the pile position deviation within 50mm, install the mixing pile machine and level and straighten it to ensure that the verticality deviation of the drill rod is no more than 1%; S2: Fix the multi-stage three-dimensional mixing head to the lower end of the drill rod of the mixing pile machine through the internal hexagonal tube at the top, and check the sealing and unobstructedness of the grouting system and the water spraying system; S3: Start the mixing pile machine, so that the first rotating tube rotates in the forward direction at the first speed, driving the mixing plate, three-dimensional mixing component and drill bit component to rotate synchronously. At the same time, it sinks at the first lifting speed to a position 0.5-1.0m below the designed pile bottom elevation to pre-mix and break up the soil. When the construction soil layer is hard clay or dense sand layer, the water spraying system is turned on at the same time for low-pressure water spraying lubrication. S4: Keep the first rotating pipe rotating in the positive direction at the second rotation speed, and lift it at the second lifting speed at a constant speed. During the lifting process, cement slurry is continuously sprayed into the mixing area through the central channel of the drill rod. The cement slurry is sprayed out from the first grouting hole and the second grouting hole respectively. Stop grouting when the pile is lifted to 0.3-0.5m above the designed pile top elevation. S5: The first rotating tube maintains the second rotation speed and rotates in the positive direction, and sinks at a constant speed at the third lifting speed to a position 0.3-0.5m below the designed pile bottom elevation, and performs the first re-mixing; S6: The first rotating tube switches to reverse rotation, while maintaining the second rotation speed. It is then lifted at the third lifting speed to a position 0.2-0.4m above the designed pile top elevation for a second re-mixing. S7: The first rotating tube continues to rotate in the opposite direction, and the rotation speed is adjusted to the third rotation speed. It sinks to the designed pile bottom elevation at the first lifting speed and performs the third re-mixing. S8: The first rotating tube switches to forward rotation, and the rotation speed is maintained at the third rotation speed. It is lifted to the ground at the first lifting speed to complete the construction of a single pile. The multi-stage three-dimensional stirring head includes a column, a flange is fixedly connected to the top of the column, a rotating seat is fixedly connected to the top of the flange by bolts, a first rotating tube is rotatably connected inside the rotating seat, and an internal hexagonal tube for easy installation is fixedly connected to the top outer wall of the first rotating tube. The outer circumferential wall of the first rotating tube is provided with stirring plates that are evenly distributed in a circular pattern. The stirring plates are inclined and fixedly connected to the outer circumferential wall of the first rotating tube. The stirring plates are provided with equally spaced toothed grooves on one side. The outer circumference of the column is provided with four sets of three-dimensional mixing components arranged in pairs, one above the other, for mixing the soil in the X-axis and Z-axis directions respectively. The bottom end of the column is provided with a drill bit assembly that rotates in the opposite direction, and the inside of the column is provided with a drive assembly, which enables the stirring plate, the three-dimensional stirring assembly and the drill bit assembly to form a three-dimensional shearing field.

[0006] Furthermore, the drive assembly includes a third rotating tube fixedly connected to the bottom end of the first rotating tube. A first bevel gear and a third bevel gear are fixedly connected to the outer circumferential wall of the third rotating tube. The first bevel gear meshes with a second bevel gear and a ninth bevel gear respectively. The third bevel gear meshes with a fourth bevel gear and a fifth bevel gear respectively. The second bevel gear, the ninth bevel gear, the fourth bevel gear, and the fifth bevel gear are all fixedly connected to the first rotating column of the corresponding three-dimensional stirring assembly.

[0007] Furthermore, the three-dimensional stirring assembly includes a connecting cylinder fixedly connected to the outer circumference of the column, a first rotating column rotatably connected to one end of the connecting cylinder, a stirring cylinder fixedly connected to the outer end of the first rotating column, and blades evenly distributed on the outer circumference of the stirring cylinder, the length of the blades gradually increasing in a clockwise direction, and the blades on the outer circumference of the stirring cylinder are all staggered.

[0008] Furthermore, the bottom end of the third rotating tube is rotatably connected to a second rotating tube, and an eighth bevel gear is fixedly connected to the outer circumference of the second rotating tube. The eighth bevel gear meshes with a seventh bevel gear, and the seventh bevel gear is rotatably connected to the inner wall of the cylinder through a rotating shaft. On the other side of the seventh bevel gear, a sixth bevel gear fixed on the third rotating tube meshes with the seventh bevel gear. The second rotating tube and the third rotating tube rotate in opposite directions.

[0009] Furthermore, the drill bit assembly is fixedly connected to the bottom end of the second rotating tube, including a soil-breaking cone. A toothed rack is fixedly connected to the outer circumference of the soil-breaking cone, and carbide cutter heads with equal spacing are fixedly connected to the bottom edge of the soil-breaking cone. A first grouting hole is opened at the center of the bottom end.

[0010] Furthermore, the racks are spirally arranged on the outer circumference of the ground-breaking cone, with gaps between adjacent racks.

[0011] Furthermore, the outer circumferential wall of the second rotating tube is fixedly connected with a dispersion plate that is distributed in a circular pattern at equal intervals. The dispersion plate includes a horizontal part and a wavy curved part, both of which have a rhomboid cross-section. The outer circumferential wall of the second rotating tube is provided with a second spray hole, and the second spray hole is located above the dispersion plate.

[0012] Furthermore, for different soil types, the process parameters for each step are matched according to the following rules: Soft soil layer: First rotation speed 60-80 r / min, second rotation speed 80-100 r / min, third rotation speed 40-60 r / min, first lifting speed 0.8-1.2 m / min, second lifting speed 0.5-0.8 m / min, third lifting speed 0.3-0.5 m / min, shotcrete pressure 0.3-0.4 MPa; Clay layer: First rotation speed 50-70 r / min, second rotation speed 70-90 r / min, third rotation speed 30-50 r / min, first lifting speed 0.6-1.0 m / min, second lifting speed 0.4-0.6 m / min, third lifting speed 0.2-0.4 m / min, shotcrete pressure 0.4-0.5 MPa; Sand layer: First rotation speed 70-90 r / min, second rotation speed 90-110 r / min, third rotation speed 50-70 r / min, first lifting speed 1.0-1.4 m / min, second lifting speed 0.6-0.9 m / min, third lifting speed 0.4-0.6 m / min, shotcrete pressure 0.5-0.6 MPa; When encountering the interface between soft and hard soil layers, within a 1.0m range above and below the interface, reduce the stirring speed by 10-20 r / min, reduce the lifting speed by 0.1-0.2 m / min, and add one more up-and-down reciprocating stirring.

[0013] Furthermore, in step S4, the water-cement ratio of the cement slurry is 0.45-0.65, and the amount of slurry sprayed is determined according to the designed cement admixture ratio of the pile body, with the error controlled within ±5%. At the same time, the cement slurry is prepared using a double-barrel continuous slurry mixer, with the primary mixing time not less than 3 minutes, and the secondary storage tank maintaining a low-speed mixing of 30-40 r / min to prevent sedimentation. Throughout the construction process, the verticality of the drill rod is monitored in real time using a verticality detector, and the amount of slurry sprayed, the slurry spraying pressure, and the amount of water sprayed are monitored in real time using flow and pressure sensors, and the data is automatically recorded.

[0014] Furthermore, during the cyclic re-mixing process, the alternating switching between forward and reverse rotation, combined with three up-and-down reciprocating mixing steps, eliminates the dead zones in the mixing. At the same time, the first re-mixing is used to initially homogenize the cement-soil mixture, the second re-mixing is used to break up the cement slurry accumulation zone, and the third re-mixing is used to ultimately improve the overall uniformity of the pile body.

[0015] The beneficial effects of this invention are: This invention provides a method for uniformly forming a circulating mixing pile. Through a drive assembly and a three-dimensional mixing assembly, the power of the mixing pile machine is transmitted to the first rotating tube via an internal hexagonal tube at the top. This first rotating tube serves as the core power input shaft, driving the mixing plates, whose outer circumference is inclined, to rotate axially around the drill rod axis. During the rotation of the mixing plates, the grooves on their edges generate a stronger cutting force on the soil, cutting large soil particles into smaller ones, thus achieving efficient axial shearing and mixing of the soil. Simultaneously, the rotation of the first rotating tube... The rotational force is simultaneously transmitted to the third rotating tube fixedly connected to its bottom end. The two sets of bevel gears installed on the outer wall of the third rotating tube mesh with the driven bevel gears corresponding to the four sets of three-dimensional mixing components, driving the four sets of mixing drums distributed in pairs to rotate at high speed around their own radial axis. The blades on the outer wall of the mixing drum are arranged in a gradually changing length and staggered manner, which can apply multi-dimensional shear force to the soil in the horizontal and vertical directions. This breaks through the technical limitation of traditional mixing piles that can only achieve axial mixing, and further reduces the radial mixing dead angle of the pile body, thereby improving the fineness of soil crushing and the uniformity of mixing.

[0016] This invention provides a method for uniformly forming a circulating mixing pile. Through a set of reverse-drive bevel gears, the bottom end of a third rotating tube drives a second rotating tube to rotate, making the rotation direction of the second rotating tube completely opposite to that of the third rotating tube. This, in turn, causes the drill bit assembly fixed at the bottom end of the second rotating tube to rotate in the opposite direction. The reverse-rotating soil-breaking cone, combined with its spirally arranged rack and carbide cutter head at the bottom edge, significantly improves the soil-breaking drilling efficiency in complex and hard soil layers such as hard clay and dense sand. Simultaneously, the reverse-rotating drill bit and the upwardly rotating mixing plate form opposing shear fields, effectively preventing the soil from seizing the drill bit due to synchronous rotation with the drill rod, further enhancing the soil breaking effect and ensuring that the soil is fully broken up. The toothed rack, with its helical arrangement and inclined N-shaped cross-section, forms a multi-bladed cutting structure when the drill bit rotates in the opposite direction. The two inclined tooth surfaces can simultaneously and continuously cut the soil at different depths and directions, significantly reducing soil breaking resistance and further improving the drilling speed of complex and hard soil layers such as hard clay and dense sand. At the same time, this inclined N-shaped tooth structure can evenly distribute the lateral impact force and axial pressure during drilling, reducing local wear and deformation of the rack and extending the overall service life of the drill bit assembly. In addition, the irregular shear surface it forms can completely destroy the integrity of the soil, preventing large pieces of soil from sticking to the drill bit and drill rod, ensuring the continuity and stability of the entire mixing construction process, and laying a more solid foundation for the uniform mixing of cement and soil.

[0017] This invention provides a method for uniformly forming a circulating mixing pile. Through the use of a dispersion plate, since the entire mixing pile construction process must follow the regulations of rising grouting and descending soil breaking, the dispersion plate fixed to the outer wall of the second rotating pipe rotates along with the worker during the descent of the mixing head for soil breaking. At this time, the dispersion plate, through its horizontally rhomboid-shaped end section, can perform secondary cutting and breaking of the large clumps of soil initially broken above the drill bit during the reverse rotation. The double-sloped structure of the rhomboid section can uniformly guide the cut soil radially outward, preventing soil accumulation in the transition area between the drill bit and the pile body, thus effectively reducing overall drilling resistance. Simultaneously, the reverse-rotating dispersion plate and the upper forward-rotating mixing plate form an intermediate-level reverse shear layer, further preventing the soil from rotating synchronously with the drill rod, fundamentally eliminating the "drill sticking" and "drill jamming" phenomena that are very likely to occur in hard clay layers. After the soil breaking work is completed, the worker applies cement slurry through... The drill rod's central channel is fed downwards, while the entire mixing head is lifted upwards. At this time, cement slurry is simultaneously ejected from two points: the first slurry hole at the center of the drill bit's bottom and the second slurry hole at the top of the rotating tube. The cement slurry ejected from the first slurry hole (main) is directly sprayed downwards to the deepest part of the pile bottom, filling the pores of the soil at the pile end and fully mixing with the pre-crushed soil at the pile bottom. This solves the problem of insufficient cement content at the pile bottom, resulting in "hanging piles," which is a problem in traditional processes. Meanwhile, the cement slurry ejected from the second slurry hole (secondary) falls precisely onto the wavy curved part of the counter-rotating dispersion plate below. On the one hand, it is dispersed into droplets by the uneven surface and evenly projected in all directions under the action of centrifugal force, covering the entire cross-section of the pile body to eliminate the blind spots of cement at the edges. On the other hand, the multi-directional local vortex generated by the rotation of the curved part forms a forced turbulent mixing field. The rhomboid cross-section structure also guides the cement slurry to flow up and down to form a high-strength mixing layer. At the same time, the counter-rotating dispersion plate can prevent the cement slurry from flowing along the outer wall of the drill rod, effectively solving the problem of slurry leakage caused by traditional processes. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments 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 overall frontal three-dimensional structure of the multi-stage stirring head in this invention.

[0020] Figure 2 This is a bottom view of the overall structure of the multi-stage stirring head in this invention.

[0021] Figure 3 For the present invention Figure 2A magnified structural diagram of point A in the middle.

[0022] Figure 4 This is a schematic diagram of the overall frontal planar structure of the multi-stage stirring head in this invention.

[0023] Figure 5 This is a schematic diagram of the overall half-sectional structure of the multi-stage stirring head in this invention.

[0024] Figure 6 For the present invention Figure 5 A magnified structural diagram at point B in the middle.

[0025] Figure 7 For the present invention Figure 5 A magnified structural diagram at point C.

[0026] Figure 8 This is a partial structural diagram of the multi-stage stirring head in this invention.

[0027] Figure 9 For the present invention Figure 8 A magnified structural diagram at point D.

[0028] In the picture: 1. Column; 2. Hexagonal socket tube; 3. First rotating tube; 4. Mixing plate; 5. Gear groove; 6. Rotating seat; 7. Flange; 8. Three-dimensional mixing assembly; 801. Mixing drum; 802. First rotating column; 803. Blade; 804. Connecting cylinder; 9. Drill bit assembly; 901. Soil-breaking cone; 902. Rack; 903. Gap; 904. Cutting head; 905. First spray hole; 10. Second rotating tube; 11. Dispersion plate; 1101. Horizontal part; 1102. Bending part; 12. Second spray hole; 13. Third rotating tube; 14. First bevel gear; 15. Second bevel gear; 16. Third bevel gear; 17. Fourth bevel gear; 18. Fifth bevel gear; 19. Sixth bevel gear; 20. Seventh bevel gear; 21. Rotating shaft; 22. Eighth bevel gear; 23. Ninth bevel gear. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0030] Please see Figure 1 - Figure 9 A method for achieving uniform forming of circulating mixing piles, employing a multi-stage three-dimensional mixing head for construction, includes the following steps: S1: Level the construction site, remove ground and underground obstacles, measure and set out the pile positions, control the pile position deviation within 50mm, install the mixing pile machine and level and straighten it to ensure that the verticality deviation of the drill rod is no more than 1%; S2: Connect the multi-stage three-dimensional mixing head to the lower end of the drill rod of the mixing pile machine through the internal hexagonal tube 2 at the top, and check the sealing and smoothness of the grouting system and the water spraying system; S3: Start the mixing pile machine, so that the first rotating pipe 3 rotates in the forward direction at the first speed, driving the mixing plate 4, the three-dimensional mixing component 8 and the drill bit component 9 to rotate synchronously. At the same time, it sinks at the first lifting speed to a position 0.5-1.0m below the designed pile bottom elevation to pre-mix and break up the soil. When the construction soil layer is hard clay or dense sand, the water spraying system is turned on at the same time for low-pressure water spraying lubrication. S4: Keep the first rotating pipe 3 rotating in the positive direction at the second rotation speed, and lift it at the second lifting speed at a constant speed. During the lifting process, cement slurry is continuously sprayed into the mixing area through the central channel of the drill rod. The cement slurry is sprayed out from the first spray hole 905 and the second spray hole 12 respectively. Stop spraying when the pile is lifted to 0.3-0.5m above the designed pile top elevation. S5: The first rotating tube 3 maintains the second rotation speed and rotates in the positive direction, and sinks at a constant speed at the third lifting speed to a position 0.3-0.5m below the designed pile bottom elevation, and performs the first re-mixing; S6: The first rotating tube 3 switches to reverse rotation, while maintaining the second rotation speed. It is then lifted at the third lifting speed to a position 0.2-0.4m above the designed pile top elevation for a second re-mixing. S7: The first rotating tube 3 keeps rotating in the opposite direction, and the rotation speed is adjusted to the third rotation speed. It sinks to the designed pile bottom elevation at the first lifting speed and performs the third re-stirring. S8: The first rotating tube 3 switches to forward rotation, and the rotation speed is maintained at the third rotation speed. It is lifted to the ground at the first lifting speed to complete the construction of a single pile. The multi-stage three-dimensional mixing head includes a column 1, a flange 7 fixedly connected to the top of the column 1, a rotating seat 6 fixedly connected to the top of the flange 7 by bolts, a first rotating tube 3 rotatably connected inside the rotating seat 6, and an internal hexagonal tube 2 for easy installation fixedly connected to the top outer wall of the first rotating tube 3. The outer circumference of the first rotating tube 3 is provided with stirring plates 4 that are evenly distributed in a circular pattern. The stirring plates 4 are fixedly connected to the outer circumference of the first rotating tube 3 at an incline. The stirring plates 4 have equally spaced toothed grooves 5 on one side. The first rotating tube 3 can drive the stirring plates 4, which are arranged at an incline on its outer circumference, to rotate axially around the drill rod axis. During the rotation of the stirring plates 4, the toothed grooves 5 on its edge can generate a stronger cutting force on the soil, cutting large pieces of soil into smaller particles and completing the efficient axial shearing and mixing of the soil. The outer circumference of column 1 is provided with four sets of three-dimensional mixing components 8 arranged in pairs, one above the other, for mixing the soil in the X-axis and Z-axis directions respectively. The bottom end of the column 1 is provided with a drill bit assembly 9 that rotates in the opposite direction. The inside of the column 1 is provided with a drive assembly, which enables the stirring plate 4, the three-dimensional stirring assembly 8 and the drill bit assembly 9 to form a three-dimensional shearing field.

[0031] Preferably, the drive assembly includes a third rotating tube 13 fixedly connected to the bottom end of the first rotating tube 3. A first bevel gear 14 and a third bevel gear 16 are fixedly connected to the outer circumference of the third rotating tube 13. The first bevel gear 14 meshes with a second bevel gear 15 and a ninth bevel gear 23, respectively. The third bevel gear 16 meshes with a fourth bevel gear 17 and a fifth bevel gear 18, respectively. The second bevel gear 15, the ninth bevel gear 23, the fourth bevel gear 17, and the fifth bevel gear 18 are all fixedly connected to the first rotating column 802 of the corresponding three-dimensional stirring assembly 8. The three-dimensional stirring assembly 8 includes a connecting cylinder 804 fixedly connected to the outer circumference of the column 1. One end of the connecting cylinder 804 is rotatably connected to the first rotating column 802. The outer end of the first rotating column 802 is fixedly connected to a stirring cylinder 801. The outer circumference of the stirring cylinder 801 is fixedly connected with equidistantly spaced... The blades 803 of the mixing drum 801 have a length that gradually increases in a clockwise direction. The blades 803 on the outer circumference of the mixing drum 801 are staggered. The rotational power of the first rotating tube 3 is simultaneously transmitted to the third rotating tube 13 fixedly connected to its bottom end. The two sets of bevel gears installed on the outer wall of the third rotating tube 13 mesh with the driven bevel gears corresponding to the four sets of three-dimensional mixing components 8, driving the four sets of mixing drums 801, which are distributed in pairs, to rotate at high speed around their own radial axis. The blades 803 on the outer wall of the mixing drum 801 are arranged in a way that gradually changes in length and is staggered, which can apply multi-dimensional shearing force to the soil in the horizontal and vertical directions. This breaks the technical limitation of traditional mixing piles that can only achieve axial mixing, and further reduces the radial mixing dead angle of the pile body, thereby improving the fineness of soil crushing and the uniformity of mixing.

[0032] Preferably, the bottom end of the third rotating tube 13 is rotatably connected to the second rotating tube 10. The outer circumferential wall of the second rotating tube 10 is fixedly connected to the eighth bevel gear 22, which meshes with the seventh bevel gear 20. The seventh bevel gear 20 is rotatably connected to the inner wall of the column 1 via the rotating shaft 21. The other side of the seventh bevel gear 20 meshes with the sixth bevel gear 19 fixed on the third rotating tube 13. The second rotating tube 10 and the third rotating tube 13 rotate in opposite directions. The drill bit assembly 9 is fixedly connected to the bottom end of the second rotating tube 10 and includes a soil-breaking cone 901. The outer circumferential wall of the soil-breaking cone 901 is fixedly connected to the rack 902. The bottom edge of the soil-breaking cone 901 is fixedly connected to equally spaced carbide cutter heads 904. A first slurry spraying point is opened at the center of the bottom end. The bottom end of the third rotating tube 13, through a set of reverse transmission bevel gears, drives the second rotating tube 10 to rotate, making the rotation direction of the second rotating tube 10 completely opposite to that of the third rotating tube 13. This, in turn, drives the drill bit assembly 9 fixed at the bottom end of the second rotating tube 10 to rotate in the opposite direction. The reverse-rotating soil-breaking cone 901, together with the spirally arranged rack 902 on its surface and the carbide cutter head 904 at the bottom edge, can greatly improve the soil-breaking drilling efficiency in complex and hard soil layers such as hard clay and dense sand. At the same time, the reverse-rotating drill bit and the upwardly rotating mixing plate 4 form a shearing field with opposite directions, effectively avoiding the phenomenon of soil sticking to the drill when rotating synchronously with the drill rod, further enhancing the soil breaking effect and ensuring that the soil can be fully broken up.

[0033] Preferably, the rack 902 is spirally arranged on the outer circumference of the breaking cone 901. The cross-section of the spirally arranged rack 902 is inclined N-shaped, thus forming a multi-bladed cutting structure when the drill bit rotates in the opposite direction. The two inclined tooth surfaces can simultaneously produce continuous cutting action on the soil at different depths and directions, significantly reducing soil breaking resistance and further improving the drilling speed of complex and hard soil layers such as hard clay and dense sand. At the same time, this inclined N-shaped tooth structure can evenly distribute the lateral impact force and axial pressure received during drilling, reducing local wear of the rack 902. The deformation extends the overall service life of the drill bit assembly 9. At the same time, the irregular shear surface formed by it can completely destroy the integrity of the soil, prevent large pieces of soil from sticking to the drill bit and drill rod, ensure the continuity and stability of the entire mixing construction process, and lay a more solid foundation for the uniform mixing of cement and soil. A gap 903 is formed between adjacent racks 902. The irregular shear surface formed by the helical rack 902 and the gap 903 can completely destroy the integrity of the soil, prevent large pieces of soil from sticking to the drill bit surface, and avoid the common drill sticking phenomenon in hard clay layers from the source.

[0034] Preferably, the outer circumferential wall of the second rotating pipe 10 is fixedly connected with a dispersion plate 11 that is equidistantly and circularly distributed. The dispersion plate 11 includes a horizontal part 1101 and a wavy curved part 1102, both of which have a rhomboid cross-section. The outer circumferential wall of the second rotating pipe 10 is provided with a second grouting hole 12, and the second grouting hole 12 is located above the dispersion plate 11. Since the entire mixing pile construction process must follow the regulations of rising grouting and descending soil breaking, when the workers descend the soil breaking through the mixing head, the dispersion plate 11 fixed to the outer wall of the second rotating pipe 10 will also rotate with it. At this time, the dispersion plate 11 passes through its end The horizontal section 1101 with a rhomboid cross-section can perform secondary cutting and crushing of the large soil clumps that have been initially broken above the drill bit during the reverse rotation. The double-sloping structure of the rhomboid cross-section can guide the cut soil to the radial outward evenly, avoiding the accumulation of soil in the transition area between the drill bit and the column 1 to form a "soil plug", effectively reducing the overall drilling resistance. At the same time, the reverse rotating dispersion plate 11 and the upper forward rotating mixing plate 4 form an intermediate reverse shear layer, further blocking the tendency of the soil to rotate synchronously with the drill rod, fundamentally eliminating the "drill sticking" and "drill clogging" phenomena that are very easy to occur in hard clay layers. After the excavation work is completed, the workers deliver cement slurry downwards through the central channel of the drill rod, while simultaneously lifting the entire mixing head upwards. At this point, cement slurry is simultaneously ejected from two points: the first grouting hole 905 at the center of the bottom of the drill bit and the second grouting hole 12 at the top of the rotating pipe 10. The cement slurry ejected from the first grouting hole 905 (main) is directly sprayed downwards to the deepest point of the pile bottom, filling the pores of the soil at the pile tip and fully mixing with the pre-crushed soil at the pile bottom. This solves the problem of insufficient cement content at the pile bottom, resulting in "suspended piles," a problem inherent in traditional methods. Meanwhile, the cement slurry ejected from the second grouting hole 12 (secondary)... The sprayed cement slurry falls precisely onto the wavy curved section 1102 of the counter-rotating dispersion plate 11 below. On the one hand, it is dispersed into droplets by the uneven surface and evenly projected in all directions under the action of centrifugal force, covering the entire cross-section of the pile body to eliminate the blind spots of cement at the edges. On the other hand, the multi-directional local vortex generated by the rotation of the curved section 1102 forms a forced turbulent mixing field. The rhomboid cross-section structure also guides the cement slurry to flow up and down to form a high-strength mixing layer. At the same time, the counter-rotating dispersion plate 11 can prevent the cement slurry from flowing along the outer wall of the drill rod, effectively solving the problem of slurry leakage caused by traditional processes.

[0035] Preferably, the process parameters for each step are matched according to the following rules for different soil types: Soft soil layer: First rotation speed 60-80 r / min, second rotation speed 80-100 r / min, third rotation speed 40-60 r / min, first lifting speed 0.8-1.2 m / min, second lifting speed 0.5-0.8 m / min, third lifting speed 0.3-0.5 m / min, shotcrete pressure 0.3-0.4 MPa; Clay layer: First rotation speed 50-70 r / min, second rotation speed 70-90 r / min, third rotation speed 30-50 r / min, first lifting speed 0.6-1.0 m / min, second lifting speed 0.4-0.6 m / min, third lifting speed 0.2-0.4 m / min, shotcrete pressure 0.4-0.5 MPa; Sand layer: First rotation speed 70-90 r / min, second rotation speed 90-110 r / min, third rotation speed 50-70 r / min, first lifting speed 1.0-1.4 m / min, second lifting speed 0.6-0.9 m / min, third lifting speed 0.4-0.6 m / min, shotcrete pressure 0.5-0.6 MPa; When encountering the interface between soft and hard soil layers, within a 1.0m range above and below the interface, reduce the stirring speed by 10-20 r / min, reduce the lifting speed by 0.1-0.2 m / min, and add one more up-and-down reciprocating stirring.

[0036] Preferably, in step S4, the water-cement ratio of the cement slurry is 0.45-0.65, and the amount of slurry sprayed is determined according to the designed cement admixture ratio of the pile body, with the error controlled within ±5%. At the same time, the cement slurry is prepared using a double-barrel continuous slurry mixer, with the primary mixing time not less than 3 minutes, and the secondary storage tank maintaining low-speed mixing at 30-40 r / min to prevent sedimentation. Throughout the construction process, the verticality of the drill rod is monitored in real time using a verticality detector, and the amount of slurry sprayed, the slurry spraying pressure, and the amount of water sprayed are monitored in real time using flow and pressure sensors, and the data is automatically recorded.

[0037] Preferably, during the cyclic re-mixing process, the mixing dead zones are eliminated by alternating forward and reverse rotation and three up-and-down reciprocating mixing processes. At the same time, the first re-mixing is used to initially homogenize the cement-soil mixture, the second re-mixing is used to break up the cement slurry accumulation zone, and the third re-mixing is used to finally improve the overall uniformity of the pile body.

[0038] In summary, with the help of the above-mentioned technical solution of the present invention, when in use, the power of the mixing pile machine is transmitted to the first rotating pipe 3 through the internal hexagonal tube 2 at the top. At this time, the first rotating pipe 3 serves as the core power input shaft. The first rotating pipe 3 can drive the mixing plate 4, which is inclined on its outer circumference, to rotate axially around the drill rod axis. During the rotation of the mixing plate 4, the toothed grooves 5 on its edge can generate a stronger cutting force on the soil during the rotation, cutting large pieces of soil into smaller particles, and completing the efficient axial shearing and mixing of the soil. At the same time, the rotational power of the first rotating tube 3 is simultaneously transmitted to the third rotating tube 13 fixedly connected to its bottom end. The two sets of bevel gears installed on the outer wall of the third rotating tube 13 mesh with the driven bevel gears corresponding to the four sets of three-dimensional mixing components 8, driving the four sets of mixing drums 801 distributed in pairs to rotate at high speed around their own radial axis. The blades 803 set on the outer wall of the mixing drum 801 adopt a gradually changing length and staggered arrangement, which can apply multi-dimensional shear force in the horizontal and vertical directions to the soil. This breaks the technical limitation of traditional mixing piles that can only achieve axial mixing, further reduces the radial mixing dead angle of the pile body, thereby improving the fineness of soil crushing and the uniformity of mixing. The bottom end of the third rotating tube 13 drives the second rotating tube 10 to rotate via a set of reverse-drive bevel gears, making the rotation direction of the second rotating tube 10 completely opposite to that of the third rotating tube 13. This, in turn, causes the drill bit assembly 9 fixed at the bottom end of the second rotating tube 10 to rotate in the opposite direction. The reverse-rotating soil-breaking cone 901, in conjunction with the spirally arranged rack 902 on its surface and the carbide cutter head 904 at its bottom edge, can significantly improve the soil-breaking drilling efficiency in complex and hard soil layers such as hard clay and dense sand. At the same time, the reverse-rotating drill bit and the upwardly rotating mixing plate 4 form a shearing field with opposite directions, effectively avoiding the phenomenon of soil sticking to the drill when rotating synchronously with the drill rod, further enhancing the soil breaking effect, ensuring that the soil can be fully dispersed, and the spirally arranged rack... The 902 tooth has an inclined N-shaped cross section, which forms a multi-blade cutting structure when the drill bit rotates in the opposite direction. The two inclined tooth surfaces can simultaneously produce continuous cutting action on soil at different depths and directions, greatly reducing soil breaking resistance and further improving the drilling speed of complex and hard soil layers such as hard clay and dense sand. At the same time, this inclined N-shaped tooth structure can evenly distribute the lateral impact force and axial pressure during drilling, reduce local wear and deformation of the tooth 902, and extend the overall service life of the drill bit assembly 9. In addition, the irregular shear surface it forms can completely destroy the integrity of the soil, prevent large pieces of soil from sticking to the drill bit and drill rod, ensure the continuity and stability of the entire mixing construction process, and lay a more solid foundation for the uniform mixing of cement and soil in the future. Since the entire mixing pile construction process must follow the regulations of rising grouting and falling soil breaking, when the workers lower the mixing head to break the soil, the dispersion plate 11 fixed on the outer wall of the second rotating pipe 10 will also rotate with it. At this time, the dispersion plate 11, through its horizontal part 1101 with a rhomboid cross section at its end, can perform secondary cutting and breaking of the large soil clumps that have been initially broken above the drill bit during the reverse rotation. The double-sloped structure of the rhomboid cross section can guide the cut soil to the radial outward evenly, avoiding the accumulation of soil in the transition area between the drill bit and the column 1 to form a "soil plug", effectively reducing the overall drilling resistance. At the same time, the reverse rotating dispersion plate 11 and the upper forward rotating mixing plate 4 form an intermediate reverse shear layer, further blocking the tendency of the soil to rotate synchronously with the drill rod, fundamentally eliminating the "drill sticking" and "drill clogging" phenomena that are very easy to occur in hard clay layers. After the excavation work is completed, the workers deliver cement slurry downwards through the central channel of the drill rod, while simultaneously lifting the entire mixing head upwards. At this point, the cement slurry is simultaneously ejected from two points: the first grouting hole 905 at the center of the bottom of the drill bit and the second grouting hole 12 at the top of the rotating pipe 10. The cement slurry ejected from the first grouting hole 905 (main) is directly sprayed downwards to the deepest part of the pile bottom, filling the pores of the soil at the pile tip and fully mixing with the pre-crushed soil at the pile bottom. This solves the problem of insufficient cement content at the pile bottom, resulting in "hanging piles," a problem inherent in traditional processes. Meanwhile, the cement slurry ejected from the second grouting hole 12 (secondary) precisely falls onto the wavy curved part 1102 of the counter-rotating dispersion plate 11 below. On one hand, it is dispersed into droplets by the uneven surface and evenly projected outwards under centrifugal force, covering the entire cross-section of the pile body to eliminate blind spots in the edge cement. On the other hand, it is further dispersed by the curved part of the plate. The multi-directional local vortex generated by the rotation of the curved section 1102 forms a forced turbulent mixing field. The rhomboid cross-section structure also guides the cement slurry to flow up and down to form a high-strength mixing layer. At the same time, the counter-rotating dispersion plate 11 can prevent the cement slurry from flowing along the outer wall of the drill rod, effectively solving the problem of slurry leakage caused by traditional processes. Therefore, the dispersion plate 11 can achieve the effect of strong soil breaking and strong mixing. Finally, the dispersion plate 11, together with the upper forward-rotating mixing plate 4 and the self-rotating three-dimensional mixing component 8, forms a three-level continuous mixing system of "forced dispersion at the bottom - planar shearing in the middle - three-dimensional mixing at the top". This allows the cement slurry and soil to complete at least three shear mixing in different directions at each depth. The dispersion coefficient of the pile body strength is further reduced, ensuring that the cement slurry can fully contact the crushed soil particles, and further improving the uniformity of the mixed pile body after molding.

[0039] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for uniformly forming a circulating mixing pile body, characterized in that, Construction using a multi-stage three-dimensional mixing head includes the following steps: S1: Level the construction site, remove ground and underground obstacles, measure and set out the pile positions, control the pile position deviation within 50mm, install the mixing pile machine and level and straighten it to ensure that the verticality deviation of the drill rod is no more than 1%; S2: Connect the multi-stage three-dimensional mixing head to the lower end of the drill rod of the mixing pile machine through the internal hexagonal tube (2) at the top, and check the sealing and smoothness of the grouting system and the water spraying system; S3: Start the mixing pile machine, so that the first rotating pipe (3) rotates in the forward direction at the first speed, driving the mixing plate (4), the three-dimensional mixing component (8) and the drill bit component (9) to rotate synchronously. At the same time, it sinks at the first lifting speed to 0.5-1.0m below the designed pile bottom elevation to pre-mix and break the soil. When the construction soil layer is hard clay or dense sand layer, the water spraying system is turned on at the same time for low-pressure water spraying lubrication. S4: Keep the first rotating pipe (3) rotating in the positive direction at the second rotation speed, and lift it at the second lifting speed at a constant speed. During the lifting process, cement slurry is continuously sprayed into the mixing area through the central channel of the drill rod. The cement slurry is sprayed out from the first grouting hole (905) and the second grouting hole (12) respectively. The grouting is stopped when the pile is lifted to 0.3-0.5m above the designed pile top elevation. S5: The first rotating tube (3) maintains the second rotation speed and rotates in the positive direction. It sinks at the third lifting speed at a constant speed to a position 0.3-0.5m below the designed pile bottom elevation and performs the first re-stirring. S6: The first rotating tube (3) is switched to reverse rotation, and the rotation speed is kept at the second rotation speed. It is then lifted at the third lifting speed to a position 0.2-0.4m above the designed pile top elevation for the second re-mixing. S7: The first rotating tube (3) is kept rotating in the opposite direction. The rotation speed is adjusted to the third rotation speed. It is lowered to the designed pile bottom elevation at the first lifting speed and then stirred for the third time. S8: The first rotating tube (3) switches to forward rotation, and the rotation speed is maintained at the third rotation speed. It is lifted to the ground at the first lifting speed to complete the construction of a single pile. The multi-stage three-dimensional stirring head includes a column (1), a flange (7) is fixedly connected to the top of the column (1), a rotating seat (6) is fixedly connected to the top of the flange (7) by bolts, a first rotating tube (3) is rotatably connected inside the rotating seat (6), and an internal hexagonal tube (2) is fixedly connected to the top outer wall of the first rotating tube (3) for easy installation. The outer circumferential wall of the first rotating tube (3) is provided with stirring plates (4) that are evenly distributed in a circular pattern. The stirring plates (4) are inclined and fixedly connected to the outer circumferential wall of the first rotating tube (3). The stirring plates (4) are provided with equally spaced toothed grooves (5) on one side. The outer circumference of the column (1) is provided with four sets of three-dimensional mixing components (8) arranged in pairs, one above the other, for mixing the soil in the X-axis and Z-axis directions respectively. The bottom end of the column (1) is provided with a drill bit assembly (9) that rotates in the opposite direction. The inside of the column (1) is provided with a drive assembly, which enables the stirring plate (4), the three-dimensional stirring assembly (8) and the drill bit assembly (9) to form a three-dimensional shearing field.

2. The method for achieving uniformity forming of circulating mixing piles according to claim 1, characterized in that, The drive assembly includes a third rotating tube (13) fixedly connected to the bottom end of the first rotating tube (3). The outer circumferential wall of the third rotating tube (13) is fixedly connected to a first bevel gear (14) and a third bevel gear (16). The first bevel gear (14) meshes with a second bevel gear (15) and a ninth bevel gear (23) respectively. The third bevel gear (16) meshes with a fourth bevel gear (17) and a fifth bevel gear (18) respectively. The second bevel gear (15), the ninth bevel gear (23), the fourth bevel gear (17) and the fifth bevel gear (18) are all fixedly connected to the first rotating column (802) of the corresponding three-dimensional stirring assembly (8).

3. The method for uniform forming of circulating mixing pile body according to claim 2, characterized in that, The three-dimensional stirring assembly (8) includes a connecting cylinder (804) fixedly connected to the outer circumferential wall of the column (1). One end of the connecting cylinder (804) is rotatably connected to a first rotating column (802). The outer end of the first rotating column (802) is fixedly connected to a stirring cylinder (801). The outer circumferential wall of the stirring cylinder (801) is fixedly connected to blades (803) that are evenly distributed. The length of the blades (803) gradually increases in the clockwise direction, and the blades (803) on the outer circumferential wall of the stirring cylinder (801) are all staggered.

4. The method for achieving uniformity forming of circulating mixing piles according to claim 3, characterized in that, The bottom end of the third rotating tube (13) is rotatably connected to the second rotating tube (10). The outer circumference of the second rotating tube (10) is fixedly connected to the eighth bevel gear (22). The eighth bevel gear (22) meshes with the seventh bevel gear (20). The seventh bevel gear (20) is rotatably connected to the inner wall of the column (1) through the rotating shaft (21). The other side of the seventh bevel gear (20) meshes with the sixth bevel gear (19) fixed on the third rotating tube (13). The second rotating tube (10) and the third rotating tube (13) rotate in opposite directions.

5. The method for uniform forming of circulating mixing pile body according to claim 4, characterized in that, The drill bit assembly (9) is fixedly connected to the bottom end of the second rotating tube (10), including a soil-breaking cone (901). A rack (902) is fixedly connected to the outer circumference of the soil-breaking cone (901). Carbide cutter heads (904) with equal spacing are fixedly connected to the bottom edge of the soil-breaking cone (901). A first grouting hole (905) is opened at the center of the bottom end.

6. The method for uniform forming of circulating mixing pile body according to claim 5, characterized in that, The rack (902) is spirally arranged on the outer circumference of the soil-breaking cone (901), and a gap (903) is formed between adjacent racks (902).

7. The method for uniform forming of circulating mixing pile body according to claim 6, characterized in that, The outer circumferential wall of the second rotating tube (10) is fixedly connected with a dispersion plate (11) that is evenly distributed in a circular pattern. The dispersion plate (11) includes a horizontal part (1101) and a wavy curved part (1102), both of which have a rhomboid cross-section. The outer circumferential wall of the second rotating tube (10) is provided with a second spray hole (12), and the second spray hole (12) is located above the dispersion plate (11).

8. The method for achieving uniformity forming of circulating mixing piles according to claim 1, characterized in that, For different soil types, the process parameters for each step are matched according to the following rules: Soft soil layer: First rotation speed 60-80 r / min, second rotation speed 80-100 r / min, third rotation speed 40-60 r / min, first lifting speed 0.8-1.2 m / min, second lifting speed 0.5-0.8 m / min, third lifting speed 0.3-0.5 m / min, shotcrete pressure 0.3-0.4 MPa; Clay layer: First rotation speed 50-70 r / min, second rotation speed 70-90 r / min, third rotation speed 30-50 r / min, first lifting speed 0.6-1.0 m / min, second lifting speed 0.4-0.6 m / min, third lifting speed 0.2-0.4 m / min, shotcrete pressure 0.4-0.5 MPa; Sand layer: First rotation speed 70-90 r / min, second rotation speed 90-110 r / min, third rotation speed 50-70 r / min, first lifting speed 1.0-1.4 m / min, second lifting speed 0.6-0.9 m / min, third lifting speed 0.4-0.6 m / min, shotcrete pressure 0.5-0.6 MPa; When encountering the interface between soft and hard soil layers, within a 1.0m range above and below the interface, reduce the stirring speed by 10-20 r / min, reduce the lifting speed by 0.1-0.2 m / min, and add one more up-and-down reciprocating stirring.

9. The method for uniform forming of circulating mixing pile body according to claim 1, characterized in that, In step S4, the water-cement ratio of the cement slurry is 0.45-0.

65. The amount of slurry sprayed is determined according to the cement admixture ratio of the designed pile body, with the error controlled within ±5%. At the same time, the cement slurry is prepared using a double-barrel continuous slurry mixer. The primary mixing time is not less than 3 minutes, and the secondary storage tank is kept at a low speed of 30-40 r / min to prevent sedimentation. Throughout the construction process, the verticality of the drill rod is monitored in real time using a verticality detector, and the amount of slurry sprayed, the slurry pressure, and the amount of water sprayed are monitored in real time using flow and pressure sensors, and the data is automatically recorded.

10. The method for achieving uniformity forming of circulating mixing pile body according to claim 1, characterized in that, During the cyclic re-mixing process, the forward and reverse rotations are alternated, and three up-and-down reciprocating mixings are used to eliminate mixing dead zones. The first re-mixing is used to initially homogenize the cement-soil mixture, the second re-mixing is used to break up cement slurry accumulation areas, and the third re-mixing is used to finally improve the overall uniformity of the pile body.

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