A pile construction method that combines high-pressure jet grouting and physical mixing

Abstract

This invention discloses a pile construction method that simultaneously performs high-pressure jet grouting and physical mixing. The method includes: a drill bit injecting high-pressure water from the side to cut the soil; simultaneously, cement slurry being injected into the hole through a slurry delivery pipe from the bottom of the drill bit or the end of the drill bit during the soil cutting process; the drill bit continuously rotating and beginning to be pulled upwards; and a mixing arm extending from the side of the drill rod, which continuously mixes the mud slurry in the hole as the drill rod rotates. This invention's "hybrid" pile construction method employs a "jet-and-mix" approach, combining high-pressure water and high-pressure cement slurry cutting with simultaneous mixing in the mud slurry. It combines the advantages of traditional high-pressure jet grouting pile construction, which is not limited by pile hole depth, and physical mixing pile construction, which guarantees pile quality. Therefore, the pile construction method proposed in this invention achieves a uniform mixing effect between the injected concrete slurry and the original underground soil, resulting in high pile quality and no limitation on pile depth.

Description

Technical Field

[0001] This invention relates to the field of pile foundation construction technology, specifically a pile construction method that simultaneously performs high-pressure jet grouting and physical mixing. Background Technology

[0002] Currently, common construction methods for underground pile foundations include high-pressure jet grouting and soil mixing. However, with increasing construction depths, especially exceeding 50 meters, some drawbacks gradually emerge in these two methods: When the depth of the mixing pile exceeds 50 meters, the size of the equipment is proportional to the diameter of the pile and the construction depth. This leads to an increase in the theoretically required size of the equipment and the required rotational torque. However, due to the limitations of current mixing pile construction technology, site space, equipment size, and mechanical performance, the mixing pile method is usually not feasible when the required construction depth exceeds 50 meters.

[0003] While the size of the construction equipment for high-pressure jet grouting piles is not limited by the pile diameter or construction depth, the lack of physical mixing during operation can easily lead to uneven concrete compaction that fails to meet design requirements. Furthermore, the loose underground geology can cause accidental concrete loss. Moreover, when the construction depth exceeds 50 meters, core sampling, a crucial quality control method in high-pressure jet grouting pile construction, becomes difficult. Therefore, current high-pressure jet grouting pile construction methods suffer from inconsistent pile quality when the construction depth exceeds 50 meters due to varying geological characteristics and the inability to effectively implement testing methods. Summary of the Invention

[0004] The purpose of this invention is to overcome the above-mentioned defects and propose a pile construction method that combines high-pressure jet grouting and physical mixing.

[0005] To achieve the above objectives, the present invention is implemented as follows: A pile construction method that simultaneously performs high-pressure jet grouting and physical mixing includes at least the following: The process of using drilling tools to spray high-pressure water from the side of the drill rod or drill bit to cut the soil and make the diameter of the working face at the bottom of the hole reach the designed diameter of the pile. The above-mentioned soil cutting process is simultaneously with the step of injecting cement grout into the hole through a grout delivery pipe from the bottom of the drill bit or the end of the drill bit. Simultaneously with the above-mentioned cement slurry injection process, the drill bit continues to rotate and begins to be pulled upwards; The above-mentioned drill bit is continuously rotating and pulled upwards while the stirring arm is extended on the side of the drill rod. The stirring arm continuously stirs the mud in the hole as the drill rod rotates.

[0006] The aforementioned pile construction method, which combines high-pressure jet grouting and physical mixing simultaneously, specifically includes: Step 1: Start the high-pressure mud pump. The high-pressure mud pump draws water from the water tank. The output pressure range of the high-pressure mud pump is 0-5MPa. Low-pressure water is sprayed from the pilot hole section at the front end of the drill bit. During the pilot hole drilling process, the low-pressure water serves the following purposes: 1. Cooling the pilot hole section; 2. Removing slag (expelling the cut and detached soil from the hole); 3. Water cutting the soil. The drill bit then drills from the pilot hole to the designed depth of the pile hole. Step 2: After the drill bit reaches the designed depth of the pile hole, (the high-pressure mud pump switches to the injection medium and extracts cement slurry from the slurry preparation system). The output pressure range of the high-pressure mud pump is 40-60MPa. High-pressure water (cement slurry) is injected from the side of the drill rod or drill bit to cut the soil and make the diameter of the pile hole wall at the working face of the drill bit reach the designed diameter of the pile body; (this part can choose to inject high-pressure water or high-pressure cement slurry. Using high-pressure water can save cement slurry usage, which is energy-saving and environmentally friendly). While performing steps 3 and 2, start the second high-pressure mud pump to extract cement slurry from the slurry preparation system. The output pressure of the high-pressure mud pump is 20-60MPa. The cement slurry is injected into the pile hole through nozzles arranged on the side of the drill rod or the side of the drill bit. While steps 4 and 3 are being performed, as the output pressure of the high-pressure mud pump increases, the mixing blades on the side of the drill bit gradually open, and the mixing blades forcibly mix the cement slurry and the exfoliated soil in the pile hole; the mixing blades continuously mix the mixed soil slurry in the hole as the drill rod rotates. Step 5: Keep the drill bit rotating and start pulling it upwards, while continuing to perform steps 2 to 4; Step 6: When the drill bit is pulled upwards and reaches the designated pile position, slowly reduce the output pressure of the high-pressure mud pump until the pressure is less than 5 MPa, and retract the mixing blades on the side of the drill bit. Step 7: Continue to pull the drill bit upwards until it is removed from the pile hole.

[0007] The "hybrid" pile construction method proposed in this invention has the following advantages: The construction method employs a "spraying and mixing in one" approach, which involves cutting with high-pressure water and high-pressure cement slurry while simultaneously mixing the slurry with a mixing device. This method combines the advantages of traditional high-pressure jet grouting pile construction, which is not limited by the depth of the pile hole, and the guaranteed pile quality of physical mixing pile construction. As a result, the pile construction method proposed in this invention achieves a uniform mixing effect between the injected concrete slurry and the original underground soil, resulting in high pile quality and no limitation on pile depth.

[0008] In the high-pressure jet grouting pile method, the pile is formed by the dynamic action of concrete grout, resulting in a large amount of concrete grout used and insufficient cement content after pile formation. However, this method incorporates a physical mixing process, which reduces the amount of concrete grout used and increases the cement content, thus improving the quality of the pile. Therefore, the "integrated spraying and mixing" construction method proposed in this invention combines the characteristics of these two processes, using a certain amount of cement grout while increasing the cement content after forming. At the same time, compared with simple high-pressure jet grouting, it reduces the workload of the jet grouting process and improves the processing efficiency.

[0009] Furthermore, in the above-mentioned pile construction method that combines high-pressure jet grouting and physical mixing, while step 5 is being implemented, compressed air is sprayed from the side of the drill rod above the drill bit into the space between the hole wall and the drill rod, creating a gap between the drill rod and the hole wall.

[0010] Furthermore, the construction method proposed in this invention employs the above steps, using compressed air to create a gap between the drill rod and the borehole wall, thus preventing the collapse of the pile hole due to "vacuuming" as the drill bit is pulled upwards. The gap between the drill bit and the pile hole also gives this construction method a "micro-disturbance" effect. Compared to the mixing drill bit with helical blades used in traditional mixing pile methods, the drill bit proposed in this invention, when pulled upwards from the pile hole, does not carry away any concrete or soil that should be part of the pile body during the process, because its mixing arm volume is significantly smaller than that of traditional helical blades. This ensures the quality and integrity of the pile body.

[0011] This invention also proposes a high-pressure jet grouting drill with a retractable mixing arm: it includes a swivel, drill rod, and drill bit, as are found in conventional high-pressure jet grouting drills, and a grouting nozzle is provided on the bottom side of the drill bit; furthermore, it also includes a mixing arm located on the outside of the drill bit, one end of which is connected to the side wall of the drill rod by a pin, and the other end of which is rotatably connected to a top ring by a connecting rod. The top ring is fitted onto the drill rod. When the mixing arm is not in operation, it is retracted into the side wall of the drill rod. When the mixing arm is extended by the sliding of the top ring, it opens outward from the side wall of the drill rod and rotates with the rotation of the drill rod, thereby mixing the water, mud, and cut soil in the pile hole.

[0012] The aforementioned high-pressure rotary jet drilling tool provides high-pressure mud through a mud pump, which differs from traditional drilling tools that provide high torque through a power head. High-pressure mud cutting replaces large-sized drill bits, thereby achieving the operational effect of "small equipment size and large-diameter piles". Furthermore, compared with traditional power heads, mud pumps provide torque more efficiently and cost-effectively, and have lower maintenance efficiency.

[0013] The aforementioned high-pressure jet grouting drill bit, in the initial stage of construction, has its mixing arm in a retracted state, and the drilling process is achieved by the cutting edge at the top of the drill bit. In this way, the area of ​​damage to the surface of the construction area can be effectively reduced, which is conducive to the protection of the surrounding environment.

[0014] The above-mentioned mixed pile construction method, which combines high-pressure jet grouting and physical mixing, uses drilling tools equipped with densitometers or pressure sensors on the drill bit and mixing arm. During the drilling process, the density of the cement slurry mixture in the pile hole is collected and compared to ensure that the amount of cement in the pile body meets the design requirements.

[0015] Therefore, compared to conventional high-pressure jet grouting pile construction, which requires drilling a second hole and taking core samples to assess the underground conditions, this method uses densitometers or pressure sensors on the drill bit and mixing arm. During drilling, the data collected by these sensors is fed back to the operator. By observing changes in density or pressure within the pile hole, the operator can understand the underground conditions, including the geological characteristics of the drilling area and whether the cement grout has been effectively injected. This ensures the quality of the pile and eliminates the need for core sampling in traditional methods. Furthermore, compared to core sampling, this method offers significant advantages. This method, by setting up a density meter or pressure sensor, allows for real-time adjustments to the drilling plan during drilling operations, thereby avoiding the problems of having to backtrack or being unable to rework due to substandard pile quality. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the construction method shown in this invention. Figure 1 .

[0017] Figure 2 This is a schematic diagram of the retracted state of the drill bit shown in this invention.

[0018] Figure 3 This is a schematic diagram of the drill bit in the open state shown in this invention.

[0019] Figure 4 The diagram shown is a construction schematic of the pilot hole drilling stage in existing pile driving construction.

[0020] Figure 5 The diagram shows a construction schematic of the jet grouting and hole enlargement stage in existing pile driving construction.

[0021] Figure 6 The diagram shown is a cross-sectional view of the jet grouting drill bit in Example 1.

[0022] Figure 7 What is shown is Figure 6 A magnified view of part A in the middle.

[0023] Figure 8 The diagram shown is a cross-sectional view of the jet grouting drill bit in Example 2.

[0024] Figure 9 The diagram shown is a schematic diagram of the transmission rod in Embodiment 2.

[0025] Figure 10 The diagram shown is a cross-sectional view of the jet grouting drill bit in Example 3.

[0026] Figure 11 The diagram shown is a structural schematic of the jet grouting drill bit in Example 3 when the stirring blades are open. Detailed Implementation

[0027] The present invention will be further illustrated below through specific embodiments.

[0028] like Figures 1-3 As shown, under the premise of existing buildings, a method for repairing and reinforcing the soil beneath the building using a hybrid pile method combining high-pressure jet grouting and physical mixing is employed, including... A pile construction method that simultaneously performs high-pressure jet grouting and physical mixing includes at least the following: The process of using drilling tools to spray high-pressure water from the side of the drill rod or drill bit to cut the soil and make the diameter of the working face at the bottom of the hole reach the designed diameter of the pile. The above-mentioned soil cutting process is simultaneously with the step of injecting cement grout into the hole through a grout delivery pipe from the bottom of the drill bit or the end of the drill bit. Simultaneously with the above-mentioned cement slurry injection process, the drill bit continues to rotate and begins to be pulled upwards; The above-mentioned drill bit is continuously rotating and pulled upwards while the stirring arm is extended on the side of the drill rod. The stirring arm continuously stirs the mud in the hole as the drill rod rotates.

[0029] The aforementioned pile construction method, which combines high-pressure jet grouting and physical mixing simultaneously, specifically includes: Step 1: Start the high-pressure mud pump. The high-pressure mud pump draws water from the water tank. The output pressure range of the high-pressure mud pump is 0-5MPa. Low-pressure water is sprayed from the pilot hole section at the front end of the drill bit. During the pilot hole drilling process, the low-pressure water serves the following purposes: 1. Cooling the pilot hole section; 2. Removing slag (expelling the cut and detached soil from the hole); 3. Water cutting the soil. The drill bit then drills from the pilot hole to the designed depth of the pile hole. Step 2: After the drill bit reaches the designed depth of the pile hole, (the high-pressure mud pump switches to the injection medium and extracts cement slurry from the slurry preparation system). The output pressure range of the high-pressure mud pump is 40-60MPa. High-pressure water (cement slurry) is injected from the side of the drill rod or drill bit to cut the soil and make the diameter of the pile hole wall at the working face of the drill bit reach the designed diameter of the pile body; (this part can choose to inject high-pressure water or high-pressure cement slurry. Using high-pressure water can save cement slurry usage, which is energy-saving and environmentally friendly). While performing steps 3 and 2, start the second high-pressure mud pump to extract cement slurry from the slurry preparation system. The output pressure of the high-pressure mud pump is 20-60MPa. The cement slurry is injected into the pile hole through nozzles arranged on the side of the drill rod or the side of the drill bit. While steps 4 and 3 are being performed, as the output pressure of the high-pressure mud pump increases, the mixing blades on the side of the drill bit gradually open, and the mixing blades forcibly mix the cement slurry and the exfoliated soil in the pile hole; the mixing blades continuously mix the mixed soil slurry in the hole as the drill rod rotates. Step 5: Keep the drill bit rotating and start pulling it upwards, while continuing to perform steps 2 to 4; Step 6: When the drill bit is pulled upwards and reaches the designated pile position, slowly reduce the output pressure of the high-pressure mud pump until the pressure is less than 5 MPa, and retract the mixing blades on the side of the drill bit. Step 7: Continue to pull the drill bit upwards until it is removed from the pile hole.

[0030] The "hybrid" pile construction method proposed in this invention has the following advantages: The construction method employs a "spraying and mixing in one" approach, which involves cutting with high-pressure water and high-pressure cement slurry while simultaneously mixing the slurry with a mixing device. This method combines the advantages of traditional high-pressure jet grouting pile construction, which is not limited by the depth of the pile hole, and the guaranteed pile quality of physical mixing pile construction. As a result, the pile construction method proposed in this invention achieves a uniform mixing effect between the injected concrete slurry and the original underground soil, resulting in high pile quality and no limitation on pile depth.

[0031] In the high-pressure jet grouting pile method, the pile is formed by the dynamic action of concrete grout, resulting in a large amount of concrete grout used and insufficient cement content after pile formation. However, this method incorporates a physical mixing process, which reduces the amount of concrete grout used and increases the cement content, thus improving the quality of the pile. Therefore, the "integrated spraying and mixing" construction method proposed in this invention combines the characteristics of these two processes, using a certain amount of cement grout while increasing the cement content after forming. At the same time, compared with simple high-pressure jet grouting, it reduces the workload of the jet grouting process and improves the processing efficiency.

[0032] Furthermore, in the above-mentioned pile construction method that combines high-pressure jet grouting and physical mixing, while step 5 is being implemented, compressed air is sprayed from the side of the drill rod above the drill bit into the space between the hole wall and the drill rod, creating a gap between the drill rod and the hole wall.

[0033] Furthermore, the construction method proposed in this invention employs the above steps, using compressed air to create a gap between the drill rod and the borehole wall, thus preventing the collapse of the pile hole due to "vacuuming" as the drill bit is pulled upwards. The gap between the drill bit and the pile hole also gives this construction method a "micro-disturbance" effect. Compared to the mixing drill bit with helical blades used in traditional mixing pile methods, the drill bit proposed in this invention, when pulled upwards from the pile hole, does not carry away any concrete or soil that should be part of the pile body during the process, because its mixing arm volume is significantly smaller than that of traditional helical blades. This ensures the quality and integrity of the pile body.

[0034] This invention also proposes a high-pressure jet grouting drill with a retractable mixing arm: it includes a swivel, drill rod, and drill bit, as are found in conventional high-pressure jet grouting drills, and a grouting nozzle is provided on the bottom side of the drill bit; furthermore, it also includes a mixing arm located on the outside of the drill bit, one end of which is connected to the side wall of the drill rod by a pin, and the other end of which is rotatably connected to a top ring by a connecting rod. The top ring is fitted onto the drill rod. When the mixing arm is not in operation, it is retracted into the side wall of the drill rod. When the mixing arm is extended by the sliding of the top ring, it opens outward from the side wall of the drill rod and rotates with the rotation of the drill rod, thereby mixing the water, mud, and cut soil in the pile hole.

[0035] The aforementioned high-pressure rotary jet drilling tool provides high-pressure mud through a mud pump, which differs from traditional drilling tools that provide high torque through a power head. High-pressure mud cutting replaces large-sized drill bits, thereby achieving the operational effect of "small equipment size and large-diameter piles". Furthermore, compared with traditional power heads, mud pumps provide torque more efficiently and cost-effectively, and have lower maintenance efficiency.

[0036] The aforementioned high-pressure jet grouting drill bit, in the initial stage of construction, has its mixing arm in a retracted state, and the drilling process is achieved by the cutting edge at the top of the drill bit. In this way, the area of ​​damage to the surface of the construction area can be effectively reduced, which is conducive to the protection of the surrounding environment.

[0037] The above-mentioned mixed pile construction method, which combines high-pressure jet grouting and physical mixing, uses drilling tools equipped with densitometers or pressure sensors on the drill bit and mixing arm. During the drilling process, the density of the cement slurry mixture in the pile hole is collected and compared to ensure that the amount of cement in the pile body meets the design requirements.

[0038] Therefore, compared to conventional high-pressure jet grouting pile construction, which requires drilling a second hole and taking core samples to assess the underground conditions, this method uses densitometers or pressure sensors on the drill bit and mixing arm. During drilling, the data collected by these sensors is fed back to the operator. By observing changes in density or pressure within the pile hole, the operator can understand the underground conditions, including the geological characteristics of the drilling area and whether the cement grout has been effectively injected. This ensures the quality of the pile and eliminates the need for core sampling in traditional methods. Furthermore, compared to core sampling, this method offers significant advantages. This method, by setting up a density meter or pressure sensor, allows for real-time adjustments to the drilling plan during drilling operations, thereby avoiding the problems of having to backtrack or being unable to rework due to substandard pile quality.

[0039] Furthermore, in the above-mentioned pile construction method that combines high-pressure jet grouting and physical mixing, the following are several different embodiments for the drill bit: Example 1: A jet grouting drill bit for jet grouting construction, such as Figure 3 As shown, it includes a drill body 10, a first pressure actuation component 20, a second pressure actuation component 30, and a stirring blade 50. The structure and function of these components are described in detail below.

[0040] Reference Figure 6 The drill body 10 is rod-shaped with a diameter of 325 mm. A drill bit 14 and an axial nozzle 13 are located at the head of the drill body 10. The drill bit 14 is a three-bladed drill bit with a rotation diameter of 350 mm. There are two axial nozzles 13, positioned at an angle of 5-10° relative to the axis. A drill rod connector 60 is connected to the upper end of the drill body 10, allowing for quick connection with the drill rod. Grouting channels are provided within the drill rod and the drill rod connector 60.

[0041] The drill body 10 is hollow inside, and the second pressure actuation assembly 30 is disposed inside the drill body 10. The second pressure actuation assembly 30 includes a second piston rod 31 and a second elastic body. In this embodiment, the second elastic body is a compression spring 32, which acts on the second piston rod 31, causing the second piston rod 31 to press against the top of the inner cavity of the drill body 10. The second piston rod 31 is provided with a cement slurry inlet channel 70, which communicates with the grouting channel in the drill rod and drill rod joint 60, allowing the high-pressure cement slurry from the ground pump station to enter the second piston rod 31 through the drill rod and drill rod joint 60.

[0042] Three open grooves 43 are provided in the middle of the second piston rod 31. There are three sets of stirring blades 50, and each set of stirring blades 50 is provided with two pins. The first pin 51 is engaged with the groove 43 and can slide within the groove 43, while the second pin 52 is hinged to the drill body 10. When the pressure of the cement slurry exceeds 20MPa, the second piston rod 31 overcomes the elastic force of the compression spring 32 and begins to move downward, causing the three sets of stirring blades 50 to open outward simultaneously. The second elastic body uses the compression spring 32 because the compression stroke of the compression spring 32 is large, and the stirring blades 50 have a large opening angle, which can open outward by up to 90°.

[0043] It is worth noting that the opening and closing mechanism of the stirring blade 50 can also be of another form, such as having two pins on the stirring blade 50, one pin being hinged to the drill body 10, and the other pin being hinged to the second piston rod 31 via a connecting rod. The stirring blade 50, the drill body 10, the transmission rod 40, and the connecting rod constitute a slider-linkage mechanism, which can cause the stirring blade 50 to retract or open under the drive of the second piston rod 31.

[0044] Reference Figure 6 and Figure 7 The first pressure actuation assembly 20 includes a first piston rod 21, a first elastic body, and a radial nozzle 23. The lower end of the second piston rod 31 is provided with a lower cylinder liner 42 and a cylinder head 26, and the first piston rod 21 and the first elastic body are installed inside the lower cylinder liner 42. The first piston rod 21 also has a channel for cement slurry entry, and a conical body 17 corresponding to the channel of the first piston rod 21 is provided at the head of the drill body 10. In this embodiment, the first elastic body is a butterfly spring 22, which can provide a large elastic force within a small compression stroke, thus reducing the volume of the lower cylinder liner 42.

[0045] A tungsten carbide cone 24 and a tungsten carbide sleeve 25 are provided at the upper end of the first piston rod 21. A radial nozzle 23 is installed on the tungsten carbide sleeve 25. A perforated groove 16 corresponding to the radial nozzle 23 is provided on the drill body 10 to allow the radial nozzle 23 to spray outwards. The tungsten carbide cone 24 and the tungsten carbide sleeve 25 are wear-resistant and have a good fit. When the pressure of the cement slurry is less than 5 MPa, the pressure of the cement slurry is insufficient to compress the disc spring 22 to move the tungsten carbide cone 24 and the first piston rod 21 downwards. At this time, the tungsten carbide cone 24 and the tungsten carbide sleeve 25 are in a sealed fit, cutting off the communication between the cement slurry and the radial nozzle 23, and the radial nozzle 23 cannot spray cement slurry. At the same time, under the action of the disc spring 22, the channel on the first piston rod 21 maintains a certain distance from the cone 17, and the cement slurry can enter the axial nozzle 13 from the gap between the channel of the first piston rod 21 and the cone 17, and then be sprayed outwards. When the pressure of the cement slurry exceeds 5 MPa, the first piston rod 21 moves downward against the elastic force of the disc spring 22. At this time, the first piston rod 21 and the tungsten carbide cone 24 move downward, and the cement slurry communicates with the radial nozzle 23, spraying outward through the perforated groove 16. At the same time, a sealing fit is formed between the channel of the first piston rod 21 and the cone 17, cutting off the communication between the axial nozzle 13 and the cement slurry, and the axial nozzle 13 stops spraying outward.

[0046] Work process: Driven by the drilling rig and drill rod, the jet grouting drill bit rotates and descends, with the drill bit 14 pulverizing and excavating the soil layer. Simultaneously, the ground pump station injects cement slurry at a pressure of less than 5 MPa into the jet grouting drill bit through the drill rod. The cement slurry is ejected from the axial nozzle 13, impacting and cutting the bottom soil layer. The addition of cement slurry serves three purposes: first, it impacts and cuts the bottom soil layer; second, it softens the soil layer, facilitating the excavation of the drill bit 14; and third, as the cement slurry is discharged out of the borehole, it carries away excess soil. Clearly, this method of excavation, combining mechanical pulverization and jet cutting, significantly improves drilling efficiency.

[0047] Once the designated depth is reached, the ground pump station injects cement slurry at a pressure of 5-20 MPa into the jet grouting drill bit through the drill rod. The tungsten carbide cone 24 and the first piston rod 21 move downwards. At this time, the radial nozzle 23 begins to spray, the axial nozzle 13 stops spraying, and the stirring blades 50 are in a retracted state. After the axial nozzle 13 stops spraying, the pressure is concentrated on the radial nozzle 23. The radial nozzle 23 sprays a high-speed cement slurry jet while rotating, expanding the borehole diameter to about 1-3 m.

[0048] Then the jet grouting drill bit begins to move upwards. As the pressure of the cement grout continues to increase, when the pressure of the injected cement grout exceeds 20 MPa, the second piston rod 31 overcomes the elastic force of the compression spring 32 and begins to move downwards. Simultaneously, the three sets of mixing blades 50 open outwards. The greater the pressure of the cement grout, the greater the opening angle of the mixing blades 50. The opened mixing blades 50 ensure that the cement grout and soil are thoroughly mixed to form a homogeneous jet grouting pile, preventing quality accidents caused by uneven strength in the jet grouting pile.

[0049] As described above, this jet grouting drill bit can drill holes during downward movement and perform jet grouting and mixing during upward movement. The entire process requires only one drill rod disassembly and reassembly, significantly reducing the workload on the drilling rig and shortening the construction period. In particular, this jet grouting drill bit cleverly utilizes the varying pressure of the injected cement grout to achieve the following: during downward movement, only the axial nozzle 13 is opened; during upward movement, the axial nozzle 13 is closed, and the radial nozzle 23 is opened, followed by the opening of the mixing blades 50 to mix the cement grout and soil. Furthermore, the varying pressure of the injected cement grout and the entire operational process perfectly meet the requirements of jet grouting pile construction technology.

[0050] Practice has proven that by using this jet grouting drill bit, the construction time for each jet grouting pile has been reduced from more than 30 hours to less than 20 hours, significantly shortening the construction period.

[0051] Example 2: Reference Figure 5 Unlike Embodiment 1, the drill body 10 has a split structure, consisting of an upper split 11 and a lower split 12. The drill bit 14 and the axial nozzle 13 are located on the lower split 12, and a transmission rod 40 is connected to the lower end of the second piston rod 31. The upper split 11 and the lower split 12 transmit torque through the transmission rod 40.

[0052] Reference Figure 8 and Figure 9 An open groove 43 is located in the middle of the transmission rod 40. When the transmission rod 40 moves downward with the second piston rod 31, it enables the three sets of stirring blades 50 to open outward simultaneously. A lower cylinder sleeve 42 is located at the lower end of the transmission rod 40, and the first piston rod 21 and the first elastic body are installed inside the lower cylinder sleeve 42. Correspondingly, a tapered body 17 corresponding to the channel of the first piston rod 21 is provided on the lower split 12. Transmission surfaces 44 are milled on the upper and lower parts of the transmission rod 40, and mating surfaces that cooperate with the transmission surfaces 44 are machined on the upper split 11 and the lower split 12, respectively. The transmission surfaces 44 cooperate with the mating surfaces to transmit the rotational torque on the upper split 11 to the lower split 12.

[0053] The advantages of the split design are twofold: first, it provides space for the inward retraction of the stirring blades 50; second, it shortens the length of the drill body 10 and the second piston rod 31, and simplifies the structure of the drill body 10 and the second piston rod 31, which is beneficial to reducing assembly difficulty and manufacturing costs.

[0054] Example 3: Reference Figure 10 and Figure 11 Unlike Embodiment 2, an upper cylinder liner 41 is provided at the lower end of the second piston rod 31. The first pressure actuation assembly 20 consists of two sets, in which the first piston rod 21 and the first elastic body are installed inside the upper cylinder liner 41. Similarly, the first elastic body is a butterfly spring 22. A tungsten carbide cone 24 and a tungsten carbide sleeve 25 are provided at the upper end of the first piston rod 21. A radial nozzle 23 is installed on the tungsten carbide sleeve 25. A hollow groove 16 corresponding to the radial nozzle 23 is provided on the upper split body 11 to open a channel for the radial nozzle 23 to spray outward.

[0055] When the grouting drill bit descends, the pressure of the cement slurry is less than 5 MPa. At this time, the pressure of the cement slurry is insufficient to compress the disc spring 22, causing the tungsten carbide cone 24 and the first piston rod 21 to move downwards, and the radial nozzle 23 does not spray cement slurry. When the pressure of the cement slurry exceeds 5 MPa, the first piston rod 21 overcomes the elastic force of the disc spring 22 and moves downwards. At this time, the cement slurry is connected to the radial nozzle 23 and sprayed outwards through the perforated groove 16.

[0056] The dual first pressure actuator assemblies 20 are designed for two purposes: first, to increase the number and area of ​​radial nozzles 23; and second, to provide redundancy, ensuring that if one set of first pressure actuator assemblies 20 malfunctions, the other set can continue to operate. It is worth noting that the upper cylinder liner 41 can also be located at the upper end of the transmission rod 40.

[0057] Reference Figure 7 A high-pressure air passage 15 is provided on the upper part 11, and the nozzle of the high-pressure air passage 15 is located around the radial nozzle 23. When the radial nozzle 23 sprays cement slurry, the nozzle of the high-pressure air passage 15 sprays high-pressure air in the same direction, enveloping the cement slurry jet. The high-pressure airflow has a long range, and the high-pressure airflow enveloping the cement slurry can increase the jet velocity and range of the cement slurry, thereby increasing the penetration force of the cement slurry jet into the soil layer. For related structures and principles, please refer to the patent application number 201720233431.1.

[0058] Reference Figure 11The upper split body 11 also has a cavity 18 with a sealed cover. A pressure sensor (not shown in the figure) and a displacement sensor (not shown in the figure) are installed in the cavity 18. The pressure sensor is used to sense the pressure of the cement slurry inside the grouting drill bit, and the displacement sensor is used to sense the opening angle of the mixing blades 50. The installation of pressure and displacement sensors can provide reference for ground personnel, which is conducive to ground personnel understanding the working status of the grouting drill bit and troubleshooting in a timely manner.

Claims

1. A pile construction method that simultaneously performs high-pressure jet grouting and physical mixing, characterized in that: At least the following steps are included: The process of using drilling tools to spray high-pressure water from the side of the drill rod or drill bit to cut the soil and make the diameter of the working face at the bottom of the hole reach the designed diameter of the pile. Simultaneously with the aforementioned soil cutting process, cement grout is injected into the hole through a grout delivery pipe from the bottom of the drill bit or the end of the drill bit. Simultaneously with the above-mentioned cement slurry injection process, the drill bit continues to rotate and begins to be pulled upwards; The above-mentioned drill bit continues to rotate and be pulled upwards while the stirring arm is extended on the side of the drill rod. The stirring arm continuously stirs the mud in the hole as the drill rod rotates. One end of the mixing arm is connected to the side wall of the drill rod via a pin, and the other end of the mixing arm is rotatably connected to the top ring via a connecting rod. The top ring is fitted onto the drill rod. When the mixing arm is not working, it is retracted into the side wall of the drill rod. When the mixing arm is opened by the sliding of the top ring, it opens outward from the side wall of the drill rod and rotates with the rotation of the drill rod, thereby mixing the water, mud, and cut soil in the pile hole. The method specifically includes the following steps: Step 1: The drill bit is driven into the pilot hole and drilled down to the designed depth of the pile hole; Step 2: After the drilling tool reaches the designed depth of the pile hole, high-pressure water is sprayed from the side of the drill rod or drill bit to cut the soil and make the diameter of the pile hole wall on the working face where the drill bit is located reach the designed diameter of the pile body. While performing steps 3 and 2, concrete grout is injected into the pile hole through grouting holes opened on the side of the drill rod or the bottom and side of the drill bit. While performing steps 4 and 3, the mixing arm on the side of the drill bit is opened to mix the concrete slurry in the pile hole; the mixing arm continuously mixes the concrete slurry in the hole as the drill rod rotates. Step 5: Keep the drill bit rotating and begin to pull it upwards, while continuing to perform steps 2 to 4. Step 6: When the drill bit is pulled upwards and approaches the borehole, retract the stirring arm on the side of the drill bit; Step 7: Continue to pull the drill bit upwards until it is removed from the pile hole; In the method, the drill body is rod-shaped, and a drill bit and an axial nozzle are provided at the head of the drill body; wherein, the drill bit is a three-winged drill bit; there are two axial nozzles, which are set at an inclination of 5-10° relative to the axis; a drill rod joint is connected to the upper end of the drill body, and the drill rod joint can be quickly connected to the drill rod, and a grouting channel is provided in the drill rod and the drill rod joint. The drill body is hollow inside, and a second pressure actuation component is installed inside the drill body. The second pressure actuation component includes a second piston rod and a second elastic body. The second elastic body acts on the second piston rod, causing the second piston rod to press against the top of the drill body cavity. A cement slurry inlet channel is provided inside the second piston rod, which communicates with the grouting channel in the drill rod and drill rod joint. High-pressure cement slurry from the ground pump station can enter the second piston rod through the drill rod and drill rod joint. Three open grooves are provided in the middle of the second piston rod, and there are three sets of agitator blades. Each set of agitator blades... The blade is equipped with two pins. The first pin engages with a groove and can slide within the groove, while the second pin is hinged to the drill body. When the pressure of the cement slurry exceeds a preset threshold, the second piston rod overcomes the spring force and begins to move downward, causing the three sets of mixing blades to open outward simultaneously. Alternatively, two pins are provided on the mixing blade. One pin is hinged to the drill body, and the other pin is hinged to the second piston rod via a connecting rod. The mixing blade, drill body, transmission rod, and connecting rod constitute a slider linkage mechanism, which can cause the mixing blade to retract or open under the drive of the second piston rod.

2. The pile construction method that simultaneously performs high-pressure jet grouting and physical mixing according to claim 1, characterized in that: While step 5 is being performed, compressed air is sprayed from the side of the drill rod above the drill bit into the space between the hole wall and the drill rod, creating a gap between the drill rod and the hole wall.

3. The pile construction method that simultaneously performs high-pressure jet grouting and physical mixing according to claim 1, characterized in that: The drilling tool is equipped with a density meter or pressure sensor on its drill bit and mixing arm, and the density of the cement slurry mixture in the pile hole is collected and compared during the drilling process to ensure that the amount of cement material in the pile body meets the design requirements.

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