Variable-diameter multi-layer bidirectional interlocking mixing drill rig and construction method

Abstract

The application discloses a variable-diameter multilayer bidirectional inter-shearing stirring drilling machine, which comprises a drilling machine frame, a drill rod assembly, a power unit, a bidirectional inter-shearing stirring drill bit, a rotary jet variable-diameter unit and a grouting unit. The bidirectional inter-shearing stirring drill bit is driven by the power unit to stir in two directions. The power unit is suspended and connected to the drilling machine frame. The high-pressure rotary jet grouting channel of the rotary jet variable-diameter unit is arranged in the inner drill rod, the high-pressure rotary jet grouting port is arranged between the outer stirring frame of the bidirectional inter-shearing stirring drill bit and the drilling blade, and the curing agent slurry is sprayed out from the high-pressure rotary jet grouting channel to the high-pressure rotary jet grouting port through the high-pressure rotary jet faucet. Under the action of the power unit, the multilayer bidirectional inter-shearing stirring and the rotary high-pressure jetting are realized, and the variable-diameter bidirectional stirring pile is formed. The application also provides a variable-diameter multilayer bidirectional inter-shearing stirring construction method. The variable-diameter amount of the pile can be accurately adjusted by the high-pressure grouting pump, and the variable-diameter grouting can be realized in the designed pile section by controlling the construction parameters.

Description

Technical Field

[0001] This invention belongs to the field of curing agent mixing pile construction technology, and in particular relates to a variable diameter multi-layer bidirectional shear mixing drilling rig and construction method. Background Technology

[0002] Soft soil foundation treatment in building foundation engineering is a crucial step in ensuring project quality and accounts for a significant proportion of the total project cost. Extensive engineering practice has shown that the cement-soil mixing pile method has advantages such as simple and rapid construction, and minimal vibration, effectively improving the stability of soft soil foundations and reducing and controlling settlement. Cement-soil mixing piles have now become a commonly used method for treating weak foundations and are widely applied in foundation pit support and foundation treatment.

[0003] Existing conventional mixing pile machines are generally unidirectional, which suffers from problems such as single mixing direction, slurry overflow on the ground, uneven mixing, easy slurry blockage of the drill rod, poor pile quality, and low pile formation efficiency. Furthermore, many foundations contain soil layers of varying textures, each with different original bearing capacities, requiring mixing piles of different diameters. In foundation pit support design, the actual lateral pressure load on the upper soil layer is much smaller than the lower layer load, also necessitating mixing piles of different diameters. In engineering projects, if all piles are constructed with small diameters, the bearing capacity of the cement-soil mixing piles will be insufficient, leading to safety accidents; conversely, if all piles are constructed with large diameters, a large amount of curing agent will be wasted, increasing costs. Traditional variable cross-section piles constructed using mechanical reaming mixing drills suffer from the inability of the diameter-adjusting blades to fully open, resulting in a mixing diameter smaller than the design requirements. Controlling the gradual diameter change is difficult when using mechanical reaming mixing drills for variable diameter piles, and the construction process is overly cumbersome and complex. Summary of the Invention

[0004] To overcome at least one of the defects in the prior art, the present invention provides a variable-diameter multi-layer bidirectional shear mixing drilling rig and construction method, which can realize rapid and stepless diameter change of mixing piles according to actual construction needs, and effectively improve the pile quality of mixing piles.

[0005] To solve the above-mentioned technical problems, the present invention provides a variable-diameter multi-layer bidirectional shear mixing drill, including a drill rod assembly, a power unit, a bidirectional shear mixing drill bit, a rotary jetting variable-diameter unit, a grouting unit, and a drill frame. The drill rod assembly includes a hollow outer drill rod and an inner drill rod that can rotate relative to each other. The upper end of the outer drill rod is connected to the lower power head assembly of the power unit, and the upper end of the inner drill rod is connected to the upper power head assembly of the power unit. The lower ends of the outer drill rod and the inner drill rod are respectively connected to the bidirectional shear mixing drill bit, so that the mixing blade assembly of the bidirectional shear mixing drill bit can achieve bidirectional rotary mixing. The bidirectional shear mixing drill bit is provided with a grouting nozzle that communicates with the grouting unit. The power unit is suspended and connected to the drill frame.

[0006] The rotary jet grouting variable diameter unit includes a high-pressure rotary jet grouting nozzle, a high-pressure rotary jet grouting channel, and a high-pressure grouting pump. The high-pressure rotary jet grouting channel is located in the inner drill rod. The upper end of the high-pressure rotary jet grouting channel is connected to the high-pressure grouting pump, and the lower end is connected to the high-pressure rotary jet grouting nozzle. The high-pressure rotary jet grouting nozzle is located on the lower outer wall of the bidirectional shearing and mixing drill bit. The external curing agent slurry is injected at high pressure from the high-pressure rotary jet grouting nozzle through the high-pressure rotary jet grouting channel to achieve high-pressure cutting of the soil. Under the power of the power unit, forced rotation and high-pressure injection are achieved to form an expanded diameter reinforced body.

[0007] Furthermore, the bidirectional shear mixing drill bit includes an outer tube, an inner tube, inner tube mixing blades, outer tube mixing blades, and an outer mixing frame. The outer tube is fixedly connected to the lower end of the outer drill rod, and the inner tube is fixedly connected to the lower end of the inner drill rod. The inner tube mixing blades are fixedly connected to the outer wall of the inner tube. The upper end of the outer mixing frame is fixedly connected to the outer wall of the outer tube, and the lower end is slidably connected to the outside of the inner tube. The outer tube mixing blades are fixed to the inner side wall of the outer mixing frame, and the outer tube mixing blades and the inner tube mixing blades can rotate relative to each other. Drilling blades are also provided on the outer wall of the inner tube at the lower part of the outer mixing frame. The inner tube and outer tube rotate relative to each other under the relative rotation of the upper power head assembly and the lower power head assembly, thereby enabling bidirectional shear mixing of the bidirectional shear mixing drill bit. The high-pressure rotary jet grouting nozzle is provided on the inner tube at the lower end of the outer mixing frame.

[0008] As an improvement, the bidirectional shearing mixing drill bit has multiple outer mixing frames, which are distributed circumferentially at intervals. Each of the multiple outer mixing frames has multiple vertically arranged outer tube mixing blades on its inner wall, and the outer wall of the inner tube has inner tube mixing blades that correspond to each of the outer tube mixing blades and are alternately staggered, so as to realize multi-layer bidirectional shearing mixing.

[0009] Furthermore, the power unit includes a lower power head assembly for driving the outer drill pipe to rotate and an upper power head assembly for driving the inner drill pipe to rotate; the upper power head assembly includes an upper gear pair and an upper driver, the input teeth of the upper gear pair are connected to the power shaft of the upper driver, and the output teeth of the upper gear pair are connected to the outside of the inner drill pipe; the lower power head assembly includes a lower gear pair and a lower driver, the input teeth of the lower gear pair are connected to the power shaft of the lower driver, and the output teeth of the lower gear pair are connected to the outside of the outer drill pipe.

[0010] In a further improvement, the upper driver is an upper drive motor, and the upper gear pair includes a first gear and a second gear. The first gear is connected to the output shaft of the upper drive motor, the outer ring of the second gear meshes with the outer ring of the first gear, and the inner ring is fixedly connected to the upper end of the inner drill rod. The lower driver is a lower drive motor, and the lower gear pair includes a third gear and a fourth gear. The third gear is connected to the output shaft of the lower drive motor, the outer ring of the fourth gear meshes with the outer ring of the third gear, and the inner ring is fixedly connected to the upper end of the outer drill rod, with the fourth gear located below the second gear. The outer drill rod and the inner drill rod rotate relative to each other under the driving action of the upper and lower drive motors, thereby driving the bidirectional shearing and stirring drill bit to perform bidirectional shearing and stirring.

[0011] Furthermore, the grouting unit includes a grouting faucet and a grouting channel. The inner drill rod is provided with a core tube, which includes at least one first core tube for forming the high-pressure jet grouting channel and at least one second core tube for forming the grouting channel. The grouting nozzles of each grouting channel can be arranged at any position on the inner tube or the inner tube stirring blade or the drilling blade.

[0012] In a further improvement, a third core tube may be fitted onto the outside of each of the first core tubes, and an air jet channel is formed between the inner wall of the third core tube and the outer wall of the first core tube. An air jet port communicating with the air jet channel is provided on the outer periphery of the high-pressure rotary jet nozzle.

[0013] In a further improvement, the top of the inner drill rod is provided with a rotary joint, which is equipped with at least one grouting water tap and at least one high-pressure jet water tap. The rotary joint is also provided with an anti-rotation rod slot for inserting an anti-rotation rod to prevent the rotary joint from rotating coaxially with the inner drill rod.

[0014] In an improved version, the control systems for the grouting unit and the jet grouting variable diameter unit are integrated into the control panel of the pile driver's cab via solenoid valves.

[0015] On the other hand, the present invention also proposes a construction method for a variable-diameter multi-layer bidirectional shear mixing drilling rig, which includes the following steps:

[0016] S1: After the construction site is leveled, assemble the bidirectional mixing pile drilling rig, move the machine to the construction pile position, connect each grouting pipe and pressure grouting pump to the water tap, and prepare the back-end equipment.

[0017] S2: Start the bidirectional mixing pile drilling rig and pressure grouting pump. According to the preset construction parameters, control the power unit through the operation control module of the bidirectional mixing pile drilling rig to apply clockwise and counterclockwise torque and vertical drilling pressure to the upper and lower power head components respectively. At the same time, start the grouting unit through the grouting solenoid valve on the control panel of the cab to carry out bidirectional mixing pile drilling and mixing construction. During the drilling and mixing process, according to the design requirements, at the specified pile section and the set grouting pressure, start the rotary jet grouting variable diameter unit through the rotary jet grouting variable diameter solenoid valve on the control panel of the cab. The rotary jet grouting variable diameter unit can be started once or multiple times until the multi-layer bidirectional shear mixing and high-pressure grout rotary jet cutting reaches the design depth.

[0018] S3: After the bidirectional mixing pile reaches the design depth, according to the preset construction parameters, the power unit is controlled by the operation control module of the bidirectional mixing pile drilling rig to apply clockwise and counterclockwise torque and lifting force to the upper and lower power head components, and to carry out secondary multi-layer bidirectional shear mixing of the bidirectional mixing pile during the upward stage of the drilling rig; during the drilling and mixing process, the rotary jet grouting variable diameter unit can be operated without starting, or started once or multiple times, according to the design requirements of the bidirectional mixing pile shape, until the bidirectional mixing drill bit is lifted out of the ground, forming a variable diameter bidirectional mixing pile in the shape of "candied hawthorn" or any other shape;

[0019] S4: Based on the design requirements of the pile length, pile diameter, and shape of the bidirectional mixing pile, the construction operation of steps S2 to S3 can be repeated once.

[0020] S5: End the construction of this variable-diameter bidirectional mixing pile, move the drilling rig to the next pile location, and repeat the above construction steps.

[0021] Compared with the prior art, the present invention has the following technical effects:

[0022] 1. Based on the variable diameter bidirectional mixing drilling rig and multi-layer bidirectional shear mixing method (CS-DSM method) of the present invention, the inherent drawbacks of traditional unidirectional mixing drilling rigs, such as uneven mixing, surface slurry leakage, drill sticking and jamming, low pile strength, high material consumption, and long construction time, are solved. By applying the drilling equipment and construction method of the present invention, while reducing material consumption and saving construction time, the uniformity and pile strength of bidirectional mixing piles can be greatly improved, and the construction quality can be comprehensively improved.

[0023] 2. In the process of pile formation of variable diameter bidirectional mixing piles, by combining bidirectional mixing technology with high-pressure hydraulic cutting mixing technology, water jet technology can be used to carry out hydraulic cutting mixing simultaneously according to the pile body location and shape design while implementing multi-layer bidirectional mutual shear mixing using mechanical means. The drilling equipment of this invention is simple to operate and saves time, ensuring that the construction quality of variable diameter bidirectional mixing piles is controllable and reliable.

[0024] 3. By adopting operation control (module) technology and pre-setting pile construction parameters, the pile depth, high-pressure jet flow rate and pressure parameters can be controlled in real time. Different diameter expansion can be implemented at any pile segment at the top, bottom and middle of the pile body. The amount of curing agent added to different expansion bodies can be adjusted, thereby achieving the purpose of adjusting the strength of different pile segments and improving the bearing capacity of the whole pile. It can also construct variable diameter bidirectional mixing piles with variable size "candied hawthorn shape".

[0025] 4. The device of the present invention avoids the drawbacks of traditional mechanical expansion mixing pile drilling tools, such as complex opening and closing operations, easy damage to components, time-consuming use, and high failure rate. In addition, it completely solves the technical problem that traditional mechanical expansion mixing drilling tools cannot achieve expansion at the bottom of bidirectional mixing piles.

[0026] Furthermore, other improvements and advantages of the invention will be set forth in the following detailed description and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention can be realized and obtained through the structures particularly pointed out in the description and drawings. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of the variable-diameter multi-layer bidirectional shear mixing drill of the present invention;

[0028] Figure 2 This is a schematic diagram of the structure of the variable-diameter multi-layer bidirectional shear mixing drill rig of the present invention after the drill rig frame is removed;

[0029] Figure 3 yes Figure 2 A schematic diagram of the vertical cross-section of the multi-layer bidirectional shear mixing drilling rig with variable diameter after removing the rig frame;

[0030] Figure 4 This is a schematic diagram of the power unit structure in this invention;

[0031] Figure 5 This is a schematic diagram of the bidirectional shear stirring drill bit of the present invention;

[0032] Figure 6 This is a cross-sectional view of the drill pipe assembly in this invention;

[0033] Figure 7 This is a schematic diagram of the construction steps in Embodiment 1 of the present invention;

[0034] Figure 8 This is a cross-sectional view of the drill pipe assembly in Embodiment 2 of the present invention;

[0035] Figure 9 This is a schematic diagram of the construction steps in Embodiment 2 of the present invention.

[0036] As shown in the figure:

[0037] 1. Drill rig frame; 2. Drill rod assembly; 20. Outer drill rod; 21. Inner drill rod; 22. Core tube; 22.1. First core tube; 22.2. Second core tube; 22.3. Third core tube; 3. Power unit; 30. Upper drive; 31. Lower drive; 32. First gear; 33. Second gear; 34. Third gear; 35. Fourth gear; 36. Upper power head output shaft; 37. Lower power head output shaft; 4. Bidirectional shearing and stirring drill bit; 40. Outer tube; 41. Inner tube 42. Inner pipe mixing blade; 43. Outer pipe mixing blade; 44. Outer mixing frame; 45. Drilling blade; 46. Upper annular limiting bushing; 47. Lower annular limiting bushing; 5. Jet jet reducing unit; 50. High-pressure jet jet faucet; 51. High-pressure jet jet grouting nozzle; 52. High-pressure jet jet grouting channel; 53. Rotary joint; 54. Anti-rotation rod slot; 55. Air jet channel; 6. Grouting unit; 60. Grouting faucet; 61. Grouting nozzle; 62. Grouting channel. Detailed Implementation

[0038] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0039] like Figure 1-5 As shown: The present invention provides a variable-diameter multi-layer bidirectional shear mixing drill, including a drill rod assembly 2, a power unit 3, a bidirectional shear mixing drill bit 4, a rotary jetting variable-diameter unit 5, a grouting unit 6, and a drill frame 1. The drill rod assembly 2 includes a hollow and relatively rotatable outer drill rod 20 and an inner drill rod 21. The upper end of the outer drill rod 20 is connected to the lower power head assembly of the power unit 3, and the upper end of the inner drill rod 21 is connected to the upper power head assembly of the power unit 3. The lower ends of the outer drill rod 20 and the inner drill rod 21 are respectively connected to the bidirectional shear mixing drill bit 4. Under the bidirectional driving action of the upper and lower power head assemblies, the mixing blade assembly of the bidirectional shear mixing drill bit 4 achieves bidirectional rotary mixing. The bidirectional shear mixing drill bit 4 is provided with a grouting nozzle 61 that communicates with the grouting unit 6 to achieve simultaneous rotary mixing and grouting. In the above structure, the power unit 3 is connected and fixed to the drill frame 1 by a dedicated suspension assembly. The drill frame 1 can be a traditional frame.

[0040] In addition, to enable diameter adjustment during drilling as needed, a rotary jet diameter-changing unit 5 is also provided on the bidirectional shear mixing drill bit 4. Specifically, the rotary jet diameter-changing unit 5 includes a high-pressure rotary jet nozzle 51, a high-pressure rotary jet grouting channel 52, and a high-pressure grouting pump. The high-pressure rotary jet grouting channel 52 is located in the inner drill rod 21. The upper end of the high-pressure rotary jet grouting channel 52 is connected to the high-pressure grouting pump, and the lower end of the high-pressure rotary jet grouting channel 52 is connected to the high-pressure rotary jet nozzle 51. The high-pressure rotary jet nozzle 51 is located on the lower outer wall of the bidirectional shear mixing drill bit 4. External curing agent slurry... High-pressure jet grouting is achieved by injecting grout through the high-pressure jet grouting channel 52 and the high-pressure jet grouting nozzle 51, thereby cutting the soil under high pressure. Under the action of the upper and lower power head assemblies of the power unit 3, forced rotation and high-pressure jetting are achieved to form an expanded diameter reinforced body. The control system of the grouting unit 6 and the jet grouting diameter changing unit 5 in the above structure is integrated into the control panel of the pile driver's cab through solenoid valves, which can make the diameter changing process controllable and visible, convenient and fast. By controlling the grouting pressure and the drilling rod lifting speed, the diameter and depth of the expanded diameter reinforced body can be precisely controlled, and even "candied hawthorn-shaped" bidirectional mixing piles can be constructed.

[0041] In addition, the bidirectional shear mixing drill bit 4 in this embodiment includes an outer tube 40, an inner tube 41, an inner tube mixing blade 42, an outer tube mixing blade 43, and an outer mixing frame 44. The outer tube 40 is fixedly connected to the lower end of the outer drill rod 20, the inner tube 41 is fixedly connected to the lower end of the inner drill rod 21, the inner tube mixing blade 42 is fixedly connected to the outer wall of the inner tube 41, the upper end of the outer mixing frame 44 is fixedly connected to the outer wall of the outer tube 40, and the lower end is slidably connected to the outside of the inner tube 41. The outer tube mixing blade 43 is fixed to the inner side wall of the outer mixing frame 44, and the outer tube mixing blade 43 and the inner tube mixing blade 42 can rotate relative to each other. Drilling blades 45 are also provided on the outer wall of the inner tube 41 at the lower part of the outer mixing frame 44. The inner tube 41 and the outer tube 40 rotate relative to each other under the relative rotation of the upper power head assembly and the lower power head assembly, thereby enabling the bidirectional shear mixing drill bit 4 to perform bidirectional shear mixing. The high-pressure rotary jet grouting nozzle 51 is provided on the inner tube 41 at the lower end of the outer mixing frame 44. Specifically, in the above structure, an upper annular limiting bushing 46 is connected to the upper end of the outer mixing frame 44. The inner ring of the upper annular limiting bushing 46 is fixedly connected to the lower end of the outer tube 40. A lower annular limiting bushing 47 is connected to the lower end of the outer mixing frame 44, and the lower annular limiting bushing 47 is fitted outside the inner tube 41. That is, the lower end of the outer mixing frame 44 and the inner tube 41 can rotate relative to each other. Therefore, under the relative rotation of the outer drill rod 20 and the inner drill rod 21, the outer mixing frame 44 rotates synchronously with the outer drill rod 20 and also performs relative swirling motion with the inner tube 41. That is, the relative swirling motion between the outer tube mixing blade 43 and the inner tube mixing blade 42 is realized, which fully improves the mixing performance and ensures the quality of the mixing pile.

[0042] In this embodiment, in order to further improve the stirring effect, there are multiple outer stirring frames 44 of the bidirectional shearing stirring drill bit 4, and the multiple outer stirring frames 44 are distributed at intervals along the circumference; multiple vertically arranged outer tube stirring blades 43 are provided on the inner wall of the multiple outer stirring frames 44, and inner tube stirring blades 42 corresponding to each outer tube stirring blade 43 and alternately staggered are provided on the outer wall of the inner tube 41, so as to realize multi-layer bidirectional shearing stirring.

[0043] Other, such as Figure 2 , 3 As shown, the power unit 3 in this embodiment includes a lower power head assembly for driving the outer drill pipe 20 to rotate and an upper power head assembly for driving the inner drill pipe 21 to rotate. The upper power head assembly includes an upper gear pair and an upper driver 30. The input teeth of the upper gear pair are connected to the power shaft of the upper driver 30, and the output teeth of the upper gear pair are connected to the outside of the inner drill pipe 21. The lower power head assembly includes a lower gear pair and a lower driver 31. The input teeth of the lower gear pair are connected to the power shaft of the lower driver 31, and the output teeth of the lower gear pair are connected to the outside of the outer drill pipe 20. More specifically, in the above structure, the upper driver 30 is an upper drive motor, and the upper gear pair includes a first gear 32 and a second gear 33. The first gear 32 is connected to the output shaft of the upper drive motor, the outer ring of the second gear 33 meshes with the outer ring of the first gear 32, and the inner ring is fixedly connected to the upper end of the inner drill rod 21. Similarly, the lower driver 31 is a lower drive motor, and the lower gear pair includes a third gear 34 and a fourth gear 35. The third gear 34 is connected to the output shaft of the lower drive motor, the outer ring of the fourth gear 35 meshes with the outer ring of the third gear 34, and the inner ring is fixedly connected to the upper end of the outer drill rod 20, with the fourth gear 35 located below the second gear 33. The outer drill rod 20 and the inner drill rod 21 rotate relative to each other under the driving action of the upper and lower drive motors, thereby driving the bidirectional shearing stirring blades 43 and 42 of the bidirectional shearing stirring drill bit 4 to bidirectionally shear and stir. Of course, in other embodiments, the upper driver 30 and the lower driver 31 described above can also be hydraulic drive mechanisms, as long as they can realize the rotation of the inner drill rod 21 and the outer drill rod 20. Furthermore, in the above structure, an upper power head output shaft 36 is axially connected to the top of the inner drill rod 21, and the inner ring of the second gear 33 is fixedly fitted to the outside of the upper power head output shaft 36. Similarly, a lower power head output shaft 37 is axially connected to the top of the outer drill rod 20, and this lower power head output shaft 37 is fitted onto the outside of the upper power head output shaft 36, meaning the two components can rotate relative to each other. The inner ring of the fourth gear 36 is fixedly connected to the outside of the lower power head output shaft 37. In order to protect the gear structure from damage during construction, a gearbox 38 is installed on the outside of the upper and lower gear pairs to protect the gears.

[0044] On the other hand, such as Figure 2 , 5As shown, the grouting unit 6 in the above structure includes a grouting faucet 60 and a grouting channel 62. A core tube 22 is provided inside the inner drill rod 21. The core tube 22 includes at least one first core tube 22.1 for forming a high-pressure jet grouting channel 52 and at least one second core tube 22.2 for forming the grouting channel 62. The grouting nozzles 61 of each grouting channel 62 can be arranged at any position on the inner tube 41, the inner tube mixing blade 42, or the drilling blade 45. The cross-sectional forms of the grouting nozzles 61 and the high-pressure jet grouting nozzles 51 include, but are not limited to, circular and square shapes. Figure 2 As shown, a jet grouting body 55 of a certain diameter is formed at the high-pressure jet grouting nozzle 51. As the bidirectional shearing and mixing drill bit 4 rotates circumferentially, a circumferentially enlarged diameter jet grouting reinforcement structure is formed to achieve the forming of piles of different diameters.

[0045] More specifically, such as Figure 1 , 2 As shown, a rotary joint 53 is provided at the top of the inner drill pipe 21. The rotary joint 53 is provided with at least one grouting water tap 60 and at least one high-pressure jet water tap 50. The rotary joint 53 is also provided with an anti-rotation rod slot 54 for inserting an anti-rotation rod. By inserting the corresponding anti-rotation rod into the anti-rotation rod slot 54, the rotary joint 53 is prevented from rotating coaxially with the inner drill pipe 21, ensuring that the grouting water tap 60 and the high-pressure jet water tap 50 will not interfere with the normal operation of the drill pipe assembly 2 after being connected to the external grouting equipment.

[0046] Example 1

[0047] The engineering background of this embodiment is the construction of bidirectional mixing piles for the foundation reinforcement of multi-story residential buildings in a certain area. The design mixing piles are 13m long and 1000mm in diameter, with the top diameter expanded to 1500mm and the top expanded section length being 3m. The bottom diameter is also expanded to 1500mm and the bottom expanded section length is 3m. The bidirectional mixing piles are required to have an unconfined compressive strength of not less than 1MPa after 28 days and a composite foundation bearing capacity of not less than 120kPa.

[0048] Basic information for this embodiment: The proposed site contains several open ditches with considerable width and silt depth. Within a 20m radius, the soil layer is primarily silty clay with a cohesion of 3–10 kPa, an internal friction angle of 8–15°, and a foundation bearing capacity of 30–70 kPa. Within a 20–30m radius, the soil is silty clay with a cohesion of 30 kPa and an internal friction angle of 13°. Construction uses PO42.5 cement with 3% bentonite added (15% admixture), a water-cement ratio of 0.7, and employs a variable-diameter, multi-layer, bidirectional shear mixing drilling rig. Grouting methods include high-pressure jet grouting for diameter expansion and conventional grouting. The construction method is a variable-diameter, multi-layer, bidirectional shear mixing method. In this embodiment, the power unit 3 of the bidirectional mixing drill uses 2x37kW dual motors. The construction adopts two mixing and one spraying. The drilling speed of the inner drill rod 21 is 60r.pm, the drilling speed of the outer drill rod 20 is 35r.pm, the down-drilling speed is 0.8m / min, and the up-drilling speed is 1.2m / min. The high-pressure grouting pump used to connect with the high-pressure jet grouting water tap 50 has a grouting pressure of 30MPa.

[0049] like Figure 7 As shown in (a)-(e), the construction process of this embodiment includes the following standard steps:

[0050] S1. After the construction site is leveled, assemble the bidirectional mixing pile drilling rig, move the machine to the construction pile position, connect each grouting pipe and pressure grouting pump to the water tap, and prepare the back-end equipment.

[0051] S2. Start the bidirectional mixing pile drilling rig and pressure grouting pump. According to the preset construction parameters, control the power unit 3 through the operation control module of the bidirectional mixing pile drilling rig to apply clockwise and counterclockwise torque and vertical drilling pressure to the upper and lower power heads respectively. At the same time, start the grouting unit 6 through the grouting solenoid valve on the control panel of the cab to carry out bidirectional mixing pile drilling and mixing construction until the multi-layer bidirectional shear mixing reaches a pile bottom depth of 11m. At the same time, during the drilling and mixing process, within the 3m pile section between the pile top and pile bottom, start the rotary jet grouting variable diameter unit 5 through the rotary jet grouting variable diameter solenoid valve on the control panel of the cab to control the grouting pressure of the high-pressure grouting pump to 30MPa.

[0052] S3. After the bidirectional mixing pile reaches the designed depth of 11m, according to the preset construction parameters, the power unit 3 is controlled by the operation control module of the bidirectional mixing pile drilling rig to apply clockwise and counterclockwise torque and lifting force to the upper and lower power heads, and to carry out the secondary multi-layer bidirectional shear mixing of the bidirectional mixing pile in the upward stage of the drilling rig until the bidirectional mixing drill bit is lifted out of the ground.

[0053] S4. End the construction of this variable-diameter bidirectional mixing pile, move the drilling rig to the next pile location, and repeat the above construction steps.

[0054] Example 2

[0055] The engineering background of this embodiment is the construction of "candied hawthorn-shaped" bidirectional mixing piles for railway subgrade in a certain area. Within a depth of 20m in the project area, the soil layers are: miscellaneous fill, 1.4-5.2m thick, loose; clay, 1-3.5m thick, plastic, medium compressibility, high strength, cohesion of 26kPa, and internal friction angle of 19°; silty clay, 2-4.2m thick, low strength, cohesion of 11kPa, and internal friction angle of 9°; silty clay with silty sand, 3-5.5m thick, plastic, medium dense, medium compressibility, medium strength, cohesion of 17kPa, and internal friction angle of 22°; and silty clay, 7-15m thick, dense, high strength, cohesion of 39kPa, and internal friction angle of 26°.

[0056] Due to the poor mechanical properties of the soil layer, this embodiment adopts a "candied hawthorn-shaped" multi-layer bidirectional shear mixing pile to effectively control post-construction settlement of the railway subgrade. The designed pile length is 21m and the pile diameter is 700mm. Based on the stratum conditions and settlement requirements, high-pressure jet grouting is designed to expand the diameter at pile lengths of 0-3m, 7-10m, 13-15m, and 18-20m, with corresponding pile diameters of 1000mm, 2000mm, 1500mm, and 1500mm, respectively. KD curing agent is used in the construction, with an admixture amount of 18% and a water-cement ratio of 0.7. The requirement is that the unconfined compressive strength of the bidirectional mixing pile after 28 days is not less than 1.2MPa.

[0057] Because the diameter expansion requirement at 7-10m is relatively high in this embodiment of the bidirectional mixing pile, a double-pipe high-pressure jet grouting method is adopted. Figure 8 As shown, a third core tube 22.3 is added around the first core tube 22.1. The annular gap between the first core tube 22.1 and the third core tube 22.3 is the jet channel 55. The jet nozzle is located around the high-pressure rotary jet nozzle 51, and the upper end of the jet channel 55 is connected to the external air supply equipment. This arrangement forms an annular gas jet ring around the curing agent slurry sprayed from the high-pressure rotary jet nozzle 51. When the curing agent slurry and compressed air are sprayed simultaneously, a protective film of air is formed around the curing agent slurry jet, which can significantly reduce the pressure attenuation of the high-pressure rotary jet and make it as close as possible to the pressure attenuation rate when sprayed in air, thereby expanding the spray radius.

[0058] In this embodiment, the power unit 3 of the bidirectional mixing drill uses 2x55kW dual motors. The construction adopts two mixing and one spraying. The drilling speed of the inner drill rod 21 is 50r.pm, the drilling speed of the outer drill rod 20 is 50r.pm, the drilling speed is 0.5m / min, the drilling speed is 1m / min, the grouting pressure of the high-pressure grouting pump is 35MPa, and the air compressor pressure is 0.7MPa.

[0059] The construction procedure in this embodiment is as follows: Figure 9As shown in (a)-(e), since the construction steps are basically similar to those in Example 1, they will not be repeated. The difference is that the bidirectional mixing pile in this example is a "candied hawthorn" shaped mixing pile, while Example 1 is a bidirectional mixing pile with enlarged heads at the top and bottom of the pile.

[0060] Although the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the invention.

Claims

1. A variable-diameter multi-layer bidirectional shear mixing drilling rig, comprising a drilling rig frame (1), a drill rod assembly (2), a power unit (3), a bidirectional shear mixing drill bit (4), a rotary jet variable-diameter unit (5), and a grouting unit (6), characterized in that: The drill rod assembly (2) includes a hollow and relatively rotatable outer drill rod (20) and an inner drill rod (21). The upper end of the outer drill rod (20) is connected to the lower power head assembly of the power unit (3), and the upper end of the inner drill rod (21) is connected to the upper power head assembly of the power unit (3). The lower ends of the outer drill rod (20) and the inner drill rod (21) are respectively connected to the bidirectional shearing and stirring drill bit (4) so ​​that the stirring blade assembly of the bidirectional shearing and stirring drill bit (4) can achieve bidirectional rotation and stirring. The bidirectional shearing and stirring drill bit (4) is provided with a grouting nozzle (61) that communicates with the grouting unit (6). The power unit (3) is suspended and connected to the drilling rig frame (1). The rotary jet grouting variable diameter unit (5) includes a high-pressure rotary jet grouting nozzle (51), a high-pressure rotary jet grouting channel (52), and a high-pressure grouting pump. The high-pressure rotary jet grouting channel (52) is located in the inner drill rod (21). The upper end of the high-pressure rotary jet grouting channel (52) is connected to the high-pressure grouting pump, and the lower end is connected to the high-pressure rotary jet grouting nozzle (51). The high-pressure rotary jet grouting nozzle (51) is located on the lower outer wall of the bidirectional shearing and stirring drill bit (4). The external curing agent slurry is injected at high pressure from the high-pressure rotary jet grouting nozzle (51) through the high-pressure rotary jet grouting channel (52) to achieve high-pressure cutting of the soil. Under the power of the power unit (3), it achieves forced rotation and high-pressure injection to form an expanded diameter reinforced body. The bidirectional shearing stirring drill bit (4) includes an outer tube (40), an inner tube (41), an inner tube stirring blade (42), an outer tube stirring blade (43), and an outer stirring frame (44). The outer tube (40) is fixedly connected to the lower end of the outer drill rod (20), the inner tube (41) is fixedly connected to the lower end of the inner drill rod (21), and the inner tube stirring blade (42) is fixedly connected to the outer wall of the inner tube (41). The upper end of the outer stirring frame (44) is fixedly connected to the outer wall of the outer tube (40), and the lower end is slidably connected to the inner tube (41). 41) Externally; the outer tube stirring blade (43) is fixed on the inner wall of the outer stirring frame (44), and the outer tube stirring blade (43) and the inner tube stirring blade (42) can rotate relative to each other; a drilling blade (45) is also provided on the outer wall of the inner tube (41) at the lower part of the outer stirring frame (44); the inner tube (41) and the outer tube (40) rotate relative to each other under the relative rotation of the upper power head assembly and the lower power head assembly, thereby enabling the bidirectional shearing stirring drill bit (4) to perform bidirectional shearing stirring; the high-pressure rotary jet grouting nozzle ( 51) Set on the inner tube (41) at the lower end of the outer stirring frame (44); the outer stirring frame (44) of the bidirectional shearing stirring drill bit (4) is multiple, and the multiple outer stirring frames (44) are distributed at intervals along the circumference; multiple vertically arranged outer tube stirring blades (43) are provided on the inner wall of each of the multiple outer stirring frames (44), and multiple inner tube stirring blades (42) corresponding to each outer tube stirring blade (43) and alternately staggered are provided on the outer wall of the inner tube (41) to realize multi-layer bidirectional shearing stirring; The grouting unit (6) includes a grouting faucet (60) and a grouting channel (62). The inner drill rod (21) is provided with a core tube (22). The core tube (22) includes at least one first core tube (22.1) for forming the high-pressure jet grouting channel (52) and at least one second core tube (22.2) for forming the grouting channel (62). The grouting nozzles (61) of each grouting channel (62) can be arranged at any position on the inner tube (41), the inner tube stirring blade (42), or the drilling blade (45).

2. The variable-diameter multi-layer bidirectional shear mixing drill according to claim 1, characterized in that: The power unit (3) includes a lower power head assembly for driving the outer drill pipe (20) to rotate and an upper power head assembly for driving the inner drill pipe (21) to rotate; the upper power head assembly includes an upper gear pair and an upper driver (30), the input teeth of the upper gear pair are connected to the power shaft of the upper driver (30), and the output teeth of the upper gear pair are connected to the outside of the inner drill pipe (21); the lower power head assembly includes a lower gear pair and a lower driver (31), the input teeth of the lower gear pair are connected to the power shaft of the lower driver (31), and the output teeth of the lower gear pair are connected to the outside of the outer drill pipe (20).

3. The variable-diameter multi-layer bidirectional shear mixing drill according to claim 2, characterized in that: The upper drive (30) is an upper drive motor. The upper gear pair includes a first gear (32) and a second gear (33). The first gear (32) is connected to the output shaft of the upper drive motor. The outer ring of the second gear (33) meshes with the outer ring of the first gear (32), and the inner ring is fixedly connected to the upper end of the inner drill rod (21). The lower drive (31) is a lower drive motor. The lower gear pair includes a third gear (34) and a fourth gear (35). The third gear (34) is connected to the output shaft of the lower drive motor. The outer ring of the fourth gear (35) meshes with the outer ring of the third gear (34), and the inner ring is fixedly connected to the upper end of the outer drill rod (20). The fourth gear (35) is located below the second gear (33). The outer drill rod (20) and the inner drill rod (21) rotate relative to each other under the driving action of the upper drive motor and the lower drive motor, thereby driving the bidirectional shearing and stirring drill bit (4) to bidirectionally shear and stir.

4. A variable-diameter, multi-layer, bidirectional shear mixing drilling rig according to claim 1, characterized in that: Each of the first core tubes (22.1) may also be fitted with a third core tube (22.3). The inner wall of the third core tube (22.3.) and the outer wall of the first core tube (22.1) form an air jet channel (55). The outer periphery of the high-pressure rotary jet nozzle (51) is provided with an air jet port that communicates with the air jet channel (55).

5. A variable-diameter multi-layer bidirectional shear mixing drill according to claim 1, characterized in that: The top of the inner drill rod (21) is provided with a rotary joint (53), which is provided with at least one grouting water tap (60) and at least one high-pressure jet water tap (50). The rotary joint (53) is also provided with an anti-rotation rod slot (54) for inserting an anti-rotation rod to prevent the rotary joint (53) from rotating coaxially with the inner drill rod (21).

6. A variable-diameter multi-layer bidirectional shear mixing drilling rig according to claim 1, characterized in that: The control systems of the grouting unit (6) and the jet grouting variable diameter unit (5) are integrated into the control panel of the pile driver's cab via solenoid valves.

7. A construction method for a multi-layer bidirectional shear mixing drilling rig with variable diameter according to any one of claims 1 to 6, characterized in that, Includes the following steps: S1: After the construction site is leveled, assemble the bidirectional mixing pile drilling rig, move the machine to the construction pile position, connect each grouting pipe and pressure grouting pump to the water tap, and prepare the back-end equipment. S2: Start the bidirectional mixing pile drilling rig and pressure grouting pump. According to the preset construction parameters, control the power unit (3) through the operation control module of the bidirectional mixing pile drilling rig to apply clockwise and counterclockwise torque and vertical drilling pressure to the upper and lower power head components respectively to carry out bidirectional mixing pile drilling and mixing construction. At the same time, during the drilling and mixing process, according to the design requirements, under the specified pile section and the set grouting pressure, start the rotary jetting variable diameter unit (5). The rotary jetting variable diameter unit (5) can be started once or multiple times until the multi-layer bidirectional shearing mixing and high-pressure grout rotary jetting cutting reaches the design depth. S3: After the bidirectional mixing pile reaches the design depth, according to the preset construction parameters, the power unit (3) is controlled by the operation control module of the bidirectional mixing pile drilling machine to apply clockwise and counterclockwise torque and lifting force to the upper and lower power head components to carry out secondary multi-layer bidirectional shear mixing of the bidirectional mixing pile in the upward stage of the drilling machine; during the drilling and mixing process, the rotary jet variable diameter unit (5) can be operated without starting or starting once or multiple times according to the bidirectional mixing pile shape design requirements until the bidirectional mixing drill bit is lifted out of the ground to form a "candied hawthorn" or any shape variable diameter bidirectional mixing pile; S4: Based on the design requirements of the pile length, pile diameter, and shape of the bidirectional mixing pile, the construction operation of steps S2 to S3 can be repeated once. S5: End the construction of this variable-diameter bidirectional mixing pile, move the drilling rig to the next pile location, and repeat the above construction steps.

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