A double-shaft reciprocating stirring type deep stirring pile continuous forming device and method

Abstract

This invention discloses a dual-axis reciprocating mixing deep mixing pile continuous forming device and method, belonging to the field of foundation treatment engineering technology. The device includes a frame assembly, a vertical feeding system, a dual-axis horizontal reciprocating mixing system, and a curing agent synchronous injection system. The first and second mixing shafts of the horizontal reciprocating drive mechanism move synchronously horizontally along a horizontal guide rail. Mixing paddle assemblies are staggered on the two mixing shafts to form overlapping, full-section mixing areas during the reciprocating motion. The continuous forming method of this device maintains reciprocating shearing and grouting during the lifting and lowering of the shafts. After being raised to near the ground surface, it maintains reciprocating motion and directly moves under load to the next pile location for cyclical operation. This invention completely eliminates the mixing blind zone of traditional rotary mixing, achieves uniform mixing across the entire cross-section, and significantly improves construction efficiency and pile overlap quality through multi-pile continuous operation, effectively avoiding pile quality defects such as broken piles and reduced diameter.

Description

Technical Field

[0001] This invention belongs to the field of foundation treatment engineering technology, and relates to a device and method for continuous forming of deep mixing piles using a biaxial reciprocating mixing method. Background Technology

[0002] In existing soft soil foundation reinforcement projects, commonly used deep mixing piles and jet grouting piles mostly employ single-axis or multi-axis rotary mixing molding devices. These devices typically rely on a feed mechanism for power, using the high-speed rotation of the drill rod to drive the mixing blades at the bottom to rotary cut the in-situ soil, while simultaneously mixing the externally pumped soil stabilizer with the cut soil. This rotary mixing method has been widely used in various foundation treatment scenarios for buildings, municipal works, and transportation, and is currently one of the mainstream methods for deep reinforcement of soft soil foundations and construction of anti-seepage walls.

[0003] However, existing rotary deep mixing pile technology has significant limitations and technological defects in practical construction applications. Firstly, in rotary mixing mode, the uniformity of soil and curing agent mixing is strictly limited by the rotation radius of the mixing blades, leading to mixing blind zones at the pile edges where multiple cutting circles intersect, resulting in insufficient uniformity and stability of pile quality. Secondly, current construction processes mostly employ a single-hole, pile-by-pile operation mode. After completing a single pile, the machine must be stopped, the mixing equipment completely removed from the ground, and then the entire pile moved for positioning and construction of the next pile. This process results in low construction efficiency and excessively long time intervals between adjacent pile constructions, making it difficult to control the overlap quality between piles. Finally, in current processes, the mixing and curing of the curing agent and soil are often completed in stages, requiring waiting for the mixing equipment to be completely removed before the soil hardens. This not only leads to a long overall construction cycle but also easily causes quality defects such as pile diameter reduction and pile breakage in soft soil environments. Summary of the Invention

[0004] To address the shortcomings of existing rotary mixing pile technology, such as insufficient mixing uniformity, low single-hole operation efficiency, long curing cycle, and poor pile quality stability, this invention provides a biaxial reciprocating mixing deep mixing pile continuous forming device and method. The aim is to overcome the structural limitations of traditional rotary mixing, achieving uniform mixing of soil and curing agent across the entire cross-section to eliminate mixing blind spots. Simultaneously, it changes the single-hole, pile-by-pile operation mode, enabling continuous forming operations at multiple pile locations to improve construction efficiency and ensure pile joint quality. Ultimately, it achieves simultaneous completion of soil shear mixing and curing, shortening the construction cycle and avoiding quality defects such as pile diameter reduction and pile breakage, thereby comprehensively ensuring the stability and consistency of pile quality.

[0005] This invention is achieved through the following technical solution: A dual-axis reciprocating mixing type deep mixing pile continuous forming device includes a frame assembly, a vertical feeding system disposed on the frame assembly, a dual-axis horizontal reciprocating mixing system driven to rise and fall by the vertical feeding system, and a curing agent synchronous injection system for supplying material to the dual-axis horizontal reciprocating mixing system; The dual-shaft horizontal reciprocating stirring system includes: A horizontal guide rail is slidably mounted on the vertical feed system; The first stirring spindle and the second stirring spindle are arranged in parallel on the horizontal guide rail; A horizontal reciprocating drive mechanism is connected to the first stirring spindle and the second stirring spindle respectively, and is used to drive the first stirring spindle and the second stirring spindle to perform synchronous horizontal reciprocating linear motion along the horizontal guide rail; A stirring paddle assembly is disposed on the first stirring spindle and the second stirring spindle, and the stirring paddle assemblies on the first stirring spindle and the second stirring spindle are arranged in an alternating manner so that the two form an overlapping full-section stirring area during horizontal reciprocating motion. The curing agent synchronous injection system includes a grouting pipeline that extends to the lower ends of the first and second stirring shafts, and grouting holes that communicate with the grouting pipeline are radially opened at the lower ends of the first and second stirring shafts.

[0006] Preferably, the vertical feed system includes a vertical linear guide rail, a ball screw drive pair, a feed drive motor, and a sliding mounting bracket mounted on the frame assembly; the sliding mounting bracket is slidably connected to the vertical linear guide rail via a slider and is connected to the ball screw drive pair; the horizontal guide rail is fixed on the sliding mounting bracket.

[0007] Preferably, the horizontal reciprocating drive mechanism adopts a crank-slider mechanism with dual servo motors driving synchronously, including a first servo motor, a second servo motor, a crank disk connected to the output shafts of the first servo motor and the second servo motor respectively, a crank pin disposed on the crank disk, and a slider cooperating with the crank pin; the upper ends of the first stirring spindle and the second stirring spindle are respectively fixedly connected to the corresponding sliders.

[0008] Preferably, the agitator assemblies are arranged at equal intervals along the axial direction of the first and second agitator shafts, and multiple sets of agitator assemblies are arranged on a single shaft; each set of agitator assemblies includes symmetrically arranged agitator blades, the soil-facing surface of the agitator blades is provided with wear-resistant grooves, and the agitator blades are arranged at a 15° angle with the axis of the shaft; the bottom ends of the first and second agitator shafts are both provided with sealing and protective assemblies.

[0009] Preferably, the curing agent synchronous injection system further includes a curing agent mixing tank, a high-pressure grouting pump, a flow control valve, and a pressure sensor; the device also includes an electrical control system, which includes a PLC controller and a sensor signal acquisition module, for coordinating the control of the vertical feeding system, the dual-axis horizontal reciprocating mixing system, and the curing agent synchronous injection system.

[0010] A method for continuous forming of deep mixing piles includes the following stages: Equipment placement and alignment stage: Move the molding device to the pile location to be constructed, so that the central axes of the first and second mixing shafts are aligned with the center of the designed pile location; Dual-shaft reciprocating mixing and synchronous grouting sinking stage: The horizontal reciprocating drive mechanism is activated to drive the first mixing main shaft and the second mixing main shaft to perform synchronous horizontal reciprocating linear motion; the vertical feed system is activated to drive the main shaft to move downward, and during the sinking process, the curing agent solution is continuously injected into the soil through the grouting hole, so that the in-situ soil is uniformly mixed with the curing agent across the entire cross section under the horizontal reciprocating shearing action; Strengthening and grouting stage at the bottom of the pile: After the main shaft sinks to the designed pile bottom elevation, it maintains a horizontal reciprocating motion, controls the main shaft to reciprocate and rise multiple times within the predetermined height range, and increases the grouting pressure and grouting flow rate during the rising and falling process to carry out bottom grouting; Lifting and Continuous Forming Stage of Multiple Pile Positions: Control the main shaft to lift upwards and maintain synchronous grouting during the lifting process. When the main shaft is lifted to a preset position above the ground, stop grouting. While maintaining the horizontal reciprocating motion of the main shaft, move the entire device to the next adjacent pile position through the walking mechanism and repeat the above construction actions to form an overlapping area between adjacent cement-soil piles, thereby realizing continuous forming of multiple pile positions.

[0011] Preferably, in the biaxial reciprocating stirring and synchronous grouting sinking stage, the reciprocating frequency of the horizontal reciprocating drive mechanism is set to 8.1Hz-9.0Hz, and the amplitude is set to 180mm.

[0012] Preferably, in the biaxial reciprocating stirring and synchronous grouting sinking stage, the downward movement speed of the vertical feeding system is set to 0.76m / min-0.84m / min, the grouting pressure of the curing agent solution is set to 3.0MPa-3.4MPa, and the grouting flow rate is set to 42L / min-48L / min.

[0013] Preferably, during the bottom strengthening mixing and grouting stage of the pile body, the reciprocating lifting speed of the main shaft is adjusted to 0.2m / min, and the grouting pressure of the bottom grouting is increased to 4.3MPa-4.7MPa, and the grouting flow rate is increased to 62L / min-68L / min.

[0014] Preferably, the equipment placement and alignment stage further includes a curing agent solution preparation stage: ordinary silicate cement, slag powder, fly ash, water glass, polycarboxylate-based high-efficiency water-reducing agent, and water are added to a curing agent mixing tank and mixed to prepare a solution with a density controlled at 1.42 g / cm³. 3 -1.48g / cm 3 A curing agent solution with a viscosity controlled between 120 mPa·s and 180 mPa·s.

[0015] Compared with the prior art, the present invention has the following beneficial technical effects: This invention employs a dual-axis horizontal reciprocating mixing system. The first and second mixing shafts are parallel to each other on a horizontal guide rail and driven synchronously by a horizontal reciprocating drive mechanism. This allows the mixing paddle assemblies on the two shafts to form an overlapping, full-section mixing zone during movement, enabling complete shearing and mixing of the entire cross-section between the two shafts. This eliminates the mixing blind spots at the pile edge caused by the limited rotation radius in traditional rotary mixing methods, achieving uniform mixing of the soil and curing agent across the entire cross-section. By placing the grouting hole at the lower end of the mixing shaft and moving synchronously with it, the curing agent solution is directly injected into the soil being cut and broken as the mixing shaft horizontally reciprocates and shears the soil. This allows the injection of the curing agent and the shearing, breaking, and mixing of the soil to be completed simultaneously in the same stroke, achieving integrated mixing and grouting operations. This invention avoids the problems of uneven grout distribution and delayed curing caused by stepwise operations such as mixing before grouting or grouting before mixing. The combination of a full-section mixing area generated by the synchronous horizontal reciprocating motion of two mixing shafts and the synchronous injection through the grouting holes at the lower end of the shafts allows the curing agent solution to be rapidly and evenly dispersed throughout the entire cross-section under the coverage of the mixing blades. The soil and curing agent reach a homogeneous mixture upon completion of mixing, avoiding localized insufficient strength due to uneven mixing. The synchronous injection system for the curing agent ensures continuous grouting during the mixing, sinking, and lifting processes, and, based on homogeneous mixing throughout the entire cross-section, eliminates quality defects such as pile diameter reduction and pile breakage, achieving a pile integrity coefficient of over 0.95. The stepless adjustment of the reciprocating frequency of the horizontal reciprocating drive mechanism allows for adjustment of the shear mixing intensity according to different soil types, making the device suitable for soft soil foundation reinforcement under various engineering geological conditions. This invention can be widely applied to soft soil foundation reinforcement and anti-seepage wall construction in the fields of building, municipal, and transportation engineering. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the overall structure of the dual-axis reciprocating stirring deep mixing pile forming device of the present invention; Figure 2 This is a schematic diagram of the structure of the horizontal reciprocating drive mechanism of the present invention; Figure 3 This is a schematic diagram of the dual-shaft stirring main shaft and the staggered stirring impeller of the present invention; Figure 4 This is a top view schematic diagram of the biaxial reciprocating stirring full-section coverage and radial grouting of the present invention; Figure 5 This is a schematic diagram showing the connection between the synchronous curing agent injection system and the electrical control system of the present invention; Figure 6 This is a top view schematic diagram of the continuous forming of multiple pile positions and the overlapping of adjacent piles according to the present invention; Figure 7 This is a construction schematic diagram of the pile bottom reinforcement reciprocating mixing and grouting method of the present invention; Figure 8 This is a schematic flowchart of the continuous forming method for biaxial reciprocating mixing deep mixing piles according to the present invention. In the picture: 1. Frame assembly; 2. Portal steel structure frame; 3. Hydraulic outriggers; 4. Vertical linear guide rail; 5. Ball screw drive pair; 6. Vertical feed drive motor; 7. Sliding mounting bracket; 8. Dual-shaft horizontal reciprocating stirring system; 9. First stirring spindle; 10. Second stirring spindle; 11. Horizontal reciprocating drive mechanism; 12. First servo motor; 13. Second servo motor; 14. Crank disc; 15. Crank pin; 16. Slider; 17. Horizontal guide rail; 18. Stirring paddle assembly; 19. Agitator 20. Mixing blades; 21. Sealing and protection components; 22. Synchronous injection system for curing agent; 23. Curing agent mixing tank; 24. High-pressure grouting pump; 25. Flow control valve; 26. Pressure sensor; 27. Grouting pipeline; 28. Grouting hole; 29. ​​Electrical control system; 30. PLC controller; 31. Sensor signal acquisition module; 32. Walking mechanism; 33. Cement-soil pile; 34. Adjacent cement-soil pile; 35. Overlap area; 36. Ground; 37. Pile bottom elevation; 38. Mixing area. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0019] In this invention, the curing agent refers to a cementitious material system that can undergo a physicochemical reaction with the soil in a soft soil foundation, thereby consolidating the soil and increasing its strength. This system includes, but is not limited to, combinations of cement-based materials, slag-based materials, and admixtures.

[0020] The full-section mixing zone refers to the entire cross-sectional area perpendicular to the axis of the mixing shaft, covered by the movement trajectory of the mixing paddles on the two mixing shafts during horizontal reciprocating motion. Within this zone, the soil and solidifying agent are fully sheared and mixed, and there are no blind spots untouched by the mixing paddles.

[0021] Simultaneous curing refers to the process where the curing agent reacts with the moisture in the soil and gradually solidifies and hardens during the cutting, crushing and mixing of the soil by the mixing spindle, rather than waiting for the mixing tool to completely withdraw from the borehole before curing.

[0022] like Figures 1 to 5 As shown, this invention provides a dual-axis reciprocating mixing type deep mixing pile continuous forming device. This mechanical device includes a frame assembly 1, a vertical feeding system, a dual-axis horizontal reciprocating mixing system 8, a curing agent synchronous injection system 21, and an electrical control system 28. The specific assembly relationship and structural parameters are as follows: See Figure 1 The frame assembly 1 uses a portal steel structure frame 2 as the foundation for supporting the entire machine. The portal steel structure frame 2 is 12.6m high and 4.2m wide. Its frame columns are welded from No. 14 I-beams, and its frame beams are made of No. 16 I-beams, ensuring the high rigidity and anti-overturning ability of the entire machine during deep-level operations.

[0023] After welding, the entire structure is annealed to relieve stress. The annealing temperature is controlled between 580℃ and 620℃, and the holding time is not less than 2 hours. The structure is then cooled to room temperature in the furnace. The fillet weld height between the column and the beam is not less than 8mm. After welding, ultrasonic testing is performed according to GB / T 11345-2013, and the quality meets the Class II qualification standard.

[0024] Four adjustable-height hydraulic outriggers 3 are installed at the bottom of the frame. Each hydraulic outrigger 3 is a single-acting hydraulic cylinder with a cylinder diameter of 80mm, a rod diameter of 45mm, and a stroke of 350mm. The bottom is equipped with a 300mm diameter, 20mm thick circular pressure-bearing base plate made of Q345B material, with a 2mm deep anti-slip serration pressed onto the lower surface. The hydraulic outriggers 3 can adapt to a wide range of complex construction site flatness. The top of the frame is equipped with guide rail mounting seats with a flatness error controlled within 0.2mm / m, ensuring high-precision straightness for subsequent vertical feed from the reference plane. The hydraulic outriggers 3 are connected to a manual hydraulic pump station on the frame via pipelines, with a working pressure of 16MPa. The lifting and lowering of each outrigger can be adjusted individually by operating the reversing valve. The levelness of the frame is monitored by a frame-type level mounted on the crossbeam, with an accuracy of 0.02mm / m.

[0025] The top crossbeam of the portal steel frame 2 is equipped with guide rail mounting seats, which are two parallel steel bosses, 30mm high and 60mm wide, arranged along the length of the crossbeam. The surface of the mounting seats is milled, and the flatness error is no more than 0.2mm / m, and the parallelism error of the two guide rail mounting seats is no more than 0.15mm / m.

[0026] The vertical feed system is installed inside the beams and columns of the portal steel frame 2. The system includes two parallel vertical linear guides 4, a feed drive motor 6, a ball screw transmission pair 5, and a sliding mounting bracket 7.

[0027] Two vertical linear guides (4) are selected from THK HSR25 heavy-duty linear guides, fixed to the guide rail mounting bases on the inner side of the column with M10×35, 8.8 grade bolts, with a bolt preload torque of 45 N·m. Each guide rail is 9.8 m long, with a surface hardness of HRC58~62, and is equipped with flange-type sliders. Each slider has 4 sets of steel ball circulation loops, a dynamic load rating of 34.5 kN, and a static load rating of 54.3 kN. The parallelism error between the two guide rails is no greater than 0.15 mm / m.

[0028] The feed drive motor 6 is an AC servo motor with a rated power of 11kW, a rated speed of 1500r / min, and a rated torque of 70N·m. The motor output is equipped with a planetary gear reducer with a reduction ratio of 12:1 and an output torque of 840N·m. The motor is bolted to the upper end face of the top crossbeam, and the reducer output shaft passes through a through hole in the crossbeam and connects to the upper end of the ball screw drive pair 5. The power supply and control cables are housed within a cable chain, which is fixed to the side of the column.

[0029] The ball screw drive pair 5 has a screw diameter of 50mm, a lead of 10mm, and an accuracy grade of C3 (GB / T 17587.3-2017). The two ends of the screw are fixed to the upper and lower mounting seats of the frame respectively using angular contact ball bearings. The upper mounting seat contains a pair of 7208AC bearings mounted back-to-back, and the lower mounting seat contains a pair of 7208AC bearings mounted face-to-face. The radial runout of the bearings is no greater than 0.01mm, and the axial clearance is 0.005mm to 0.015mm. After passing through the upper mounting seat, the upper end of the screw is connected to the output shaft of the reducer using a diaphragm-type flexible coupling.

[0030] The sliding mounting bracket 7 is welded from 16mm thick Q235B steel plate. Four sliders are bolted to its back, each slidingly engaging with two vertical linear guide rails 4. A nut mounting hole is located in the center of the sliding mounting bracket 7, and the ball screw nut is bolted into this hole. A mounting flange is located on the front side of the sliding mounting bracket 7 for securing the twin-shaft horizontal reciprocating mixing system 8. The flange is 400mm in diameter and 20mm thick, with a precision-machined end face with a runout not exceeding 0.02mm. Six bolt holes are evenly distributed on the flange.

[0031] See Figures 1 to 4 The dual-shaft horizontal reciprocating stirring system 8 is fixed to the vertical feed system via a mounting flange on the sliding mounting bracket 7, and is driven by the vertical feed system to perform vertical lifting and lowering movements. The system 8 includes a first stirring spindle 9, a second stirring spindle 10, a horizontal reciprocating drive mechanism 11, a stirring paddle assembly 18, and a sealing and protection assembly 20.

[0032] The first stirring spindle 9 and the second stirring spindle 10 are arranged in parallel, with identical geometric dimensions and materials. The spindles are machined from 40Cr alloy steel tubing, with a chemical composition by mass percentage: C 0.37%~0.44%, Si 0.17%~0.37%, Mn 0.50%~0.80%, Cr 0.80%~1.10%, and the balance being Fe and unavoidable impurities. The spindle has an outer diameter of 127mm, a wall thickness of 14mm, a length of 10.2m, and a straightness error of no more than 0.08mm / m. The tempering process is as follows: heating to 850℃ in a box-type resistance furnace, holding for 60min, followed by oil quenching, then tempering at 600℃ for 90min, and finally air cooling. The hardness after tempering is HB220~250.

[0033] The upper end of the spindle is equipped with a self-aligning roller bearing 22213E, whose housing is bolted to the sliding mounting bracket 7, bearing radial loads and part of the axial loads. The lower end of the spindle is equipped with a deep groove ball bearing 6312, installed in a bearing housing within the sealing and protection assembly 20. Both upper and lower bearings are lubricated with lithium-based grease ZL-3, with a protection rating of IP67. The bearing housing and sealing housing adopt a combination structure of labyrinth seal and skeleton oil seal, allowing for long-term operation below the groundwater level.

[0034] See Figure 1 and Figure 2 The horizontal reciprocating drive mechanism 11 adopts a crank-slider mechanism with dual servo motors driving synchronously, including a first servo motor 12, a second servo motor 13, two crank discs 14, two crank pins 15, two sliders 16 and a horizontal guide rail 17.

[0035] Both the first servo motor 12 and the second servo motor 13 are AC servo motors, each with a rated power of 7.5kW, a rated speed of 3000r / min, and a rated torque of 23.9N·m. Each motor's output is equipped with a harmonic reducer with a reduction ratio of 100:1, employing a cup-shaped flexible wheel structure, outputting a torque of 2390N·m, with a hysteresis of no more than 1 arc minute. The two motors are bolted to both sides of the upper end of the sliding mounting bracket 7. The motor output shaft is keyed to the input shaft of the harmonic reducer, and the output shaft of the harmonic reducer is keyed to the crankshaft 14 and locked with a clamping nut.

[0036] The crankshaft disc 14 is disc-shaped, with a diameter of 210mm and a thickness of 25mm. It is made of 45# steel, surface hardened, with a hardened layer depth of 1.5mm to 2.0mm and a surface hardness of HRC42~48. A crank pin 15 mounting hole is formed on the crankshaft disc 14, with the center of the hole 90mm from the center of the disc, i.e., an eccentricity of 90mm. The crank pin 15 is cylindrical, with a diameter of 35mm, made of GCr15 bearing steel, and after carburizing and quenching, has a hardness of HRC58~62. It is pressed into the mounting hole of the crankshaft disc 14 with an interference fit (interference of 0.02mm to 0.04mm), and the disc is secured with a nut on the back to prevent loosening.

[0037] The horizontal guide rail 17 is a THK SHS30 linear guide rail, 2.2m long, and is bolted to the horizontal mounting surface on the front side of the sliding mounting bracket 7. The parallelism error between the two guide rails is no greater than 0.1mm / m. The slider 16 is machined from 45# steel, with a connecting hole at the upper end. A self-lubricating bearing is installed in the hole, and the crank pin 15 passes through it to form a rotating pair. The lower end of the slider 16 has a guide rail groove to mate with the horizontal guide rail 17, with a clearance of no more than 0.03mm. The surface of the slider 16 is hardened to HRC40~45. The upper ends of the first stirring spindle 9 and the second stirring spindle 10 are each equipped with a flange connecting plate, which is fixed to the corresponding slider 16 with four M20×60 high-strength bolts, with a bolt preload torque of 280N·m.

[0038] The first servo motor 12 and the second servo motor 13 rotate synchronously in opposite directions under the control of the electronic control system 28. After being reduced in speed and torque by a harmonic reducer, the servo motors drive the crank disk 14 in uniform circular motion. The crank pin 15 on the crank disk 14 rotates synchronously with the disk and slides within the connecting hole of the slider 16, converting the rotational motion of the crank disk 14 into the linear reciprocating motion of the slider 16 along the horizontal guide rail 17. The slider 16 drives the fixed stirring shaft to reciprocate synchronously, with both shafts moving simultaneously to the left and right. The amplitude of the reciprocating motion is equal to twice the eccentricity, i.e., 180mm. The maximum reciprocating frequency is 12.5Hz. The reciprocating frequency can be changed by steplessly adjusting the speed of the two servo motors through the electronic control system 28. If the amplitude needs to be changed, a crank disk 14 with a different eccentricity can be used; in this embodiment, a crank disk 14 with a fixed eccentricity of 90mm is used.

[0039] See Figure 3 and Figure 4 The agitator assemblies 18 are arranged at equal intervals along the axial direction of the first agitator shaft 9 and the second agitator shaft 10, with 18 sets per shaft and an axial spacing of 550 mm between adjacent sets. Each agitator assembly 18 contains two symmetrical agitator blades 19, extending radially outward from the shaft at the same axial position, forming a 180° symmetrical arrangement. The agitator blades 19 are made of NM400 wear-resistant alloy steel plate, 12 mm thick, 160 mm wide, and 220 mm long. The blade roots are welded to the shaft surface with double-sided fillet welds, with a weld leg height of not less than 8 mm. Three continuous wear-resistant grooves, 2.5 mm deep and spaced 35 mm apart, are cut on the soil-facing surface of the blades to guide the flow of soil and curing agent. When the agitator blades 19 perform horizontal reciprocating motion, the wear-resistant grooves on the soil-facing surface generate a shearing and guiding effect along the direction of motion, guiding the curing agent solution from near the grouting hole to the blade edge and accelerating its diffusion to both sides, increasing the distribution range of the grout in the soil.

[0040] The installation angle between the mixing blade 19 and the main shaft axis is 15°. Specifically, during welding, the root of the blade is deflected 15° relative to the radial direction of the main shaft, so that the blade generates an upward component force when it reciprocates horizontally shears the soil, promoting soil turning and mixing.

[0041] The impeller assembly 18 on the first stirring shaft 9 and the impeller assembly 18 on the second stirring shaft 10 are staggered in the axial direction. Specifically, taking a certain set of impellers on the second stirring shaft 10 as a reference, moving 275mm upward or downward along the axial direction (i.e., half of the 550mm distance between two adjacent sets), there is exactly one set of impellers on the first stirring shaft 9. In this way, the movement trajectories of the impeller blades on the first stirring shaft 9 and the impeller blades on the second stirring shaft 10 on the horizontal plane intersect and overlap, jointly covering the entire cross-section between the two shafts, forming a full-section stirring area 37.

[0042] See Figure 1The sealing and protective assembly 20 is located at the lower end of the first mixing spindle 9 and the second mixing spindle 10, and is integrated into a sealing seat by a skeleton oil seal, a dust seal, and a wear-resistant bushing. The sealing seat is cylindrical and is fixed to the lower end face of the lower bearing seat with bolts. The skeleton oil seal is made of nitrile rubber (NBR) with a steel skeleton, and the sealing lip faces the spindle surface to prevent groundwater and mud from seeping into the bearing along the spindle. It is temperature resistant from -40℃ to 120℃. The dust seal is made of polyurethane and is installed below the skeleton oil seal to block large particles of soil and gravel. The wear-resistant bushing is made of high-chromium cast iron KmTBCr26 with a hardness of HRC55~60. It is fitted on the outer surface of the spindle between the skeleton oil seal and the spindle, and the wear of the wear-resistant bushing protects the spindle surface. The overall protection rating of the sealing and protective assembly 20 is IP68, which can maintain a seal for a long time underwater and in mud. The sealing and protective assembly 20 can maintain its sealing performance for a long time below the groundwater level.

[0043] See Figure 1 and Figure 5 The curing agent synchronous injection system 21 is responsible for preparing and injecting the curing agent solution into the mixing zone 37, and includes a curing agent mixing tank 22, a high-pressure grouting pump 23, a flow control valve 24, a pressure sensor 25, and grouting pipeline 26.

[0044] Curing agent mixing tank 22, volume 2.2m³ 3 The tank is made of 304 stainless steel (06Cr19Ni10), with a wall thickness of 6mm. It is cylindrical, 1.2m in diameter and 1.8m high. The top of the tank has an inlet and a 5mm mesh screen, while the bottom has an outlet connected to the inlet of a high-pressure grouting pump 23 via a ball valve. A vertically mounted stirring shaft is installed inside the tank, with three sets of inclined paddle-type stirring blades (at a 45° angle to the shaft). A 2.2kW stirring motor is mounted on the top of the tank, rotating at 60r / min. The motor, driven by a reducer, continuously agitates the curing agent solution to prevent solid particles from settling.

[0045] The high-pressure grouting pump 23 is a variable displacement plunger pump with a rated pressure of 12 MPa and a maximum flow rate of 85 L / min. The pump inlet is connected to the outlet of the curing agent mixing tank 22, and the outlet is connected to the inlet of the flow control valve 24. The pump head has three sets of plunger-cylinder pairs, with plunger diameters of 25 mm and strokes of 40 mm. The displacement is infinitely adjustable from 0 to 85 L / min by adjusting the swashplate angle. Each pump inlet and outlet is equipped with a cone-type check valve with a hard alloy valve core and seat, and an opening pressure of 0.3 MPa to prevent backflow of the curing agent solution.

[0046] The flow control valve 24 is an electromagnetic proportional regulating valve with a direct-acting structure. The valve core position is driven by a proportional electromagnet, and the flow rate is adjusted by changing the valve opening. The adjustment accuracy is 0.5%FS (based on a full scale of 100L / min, corresponding to an absolute error of 0.5L / min). The valve inlet is connected to the outlet of the high-pressure grouting pump 23, and the outlet is connected to the grouting pipeline 26.

[0047] The pressure sensor 25 is installed on the pipeline between the flow control valve 24 and the grouting pipeline 26. It is a strain gauge type with a measurement range of 0~16MPa and an accuracy of 0.2 grade. The sensor signal output terminal is connected to the sensor signal acquisition module 30 of the electrical control system 28 via a shielded cable.

[0048] Grouting pipe 26 is made of high-pressure steel wire braided rubber hose with an inner diameter of 19mm, a rated working pressure of 16MPa, and a burst pressure of not less than 48MPa. The hose begins at the outlet of flow control valve 24 and branches off at the ends, extending to the lower ends of the first mixing shaft 9 and the second mixing shaft 10, respectively. Near the lower end of the shaft, the two branches connect to the grouting channel inside the shaft via a rotary joint, which allows for a sealed connection during horizontal reciprocating motion of the shaft. The two branches extend upwards along the outer walls of the first mixing shaft 9 and the second mixing shaft 10 to the lower end of the shaft, and are fixedly connected to the grouting channel inside the shaft. The connection is secured with a compression fitting to prevent detachment. The length of the rubber hose allows for a bending allowance of at least 2.0m during connection, accommodating the 180mm amplitude horizontal reciprocating motion of the mixing shaft without generating tensile or bending stress. Both the first mixing shaft 9 and the second mixing shaft 10 are hollow structures with an axially extending grouting channel inside, with an inner diameter of 25mm. (See also...) Figure 4 Four grouting holes 27, each 8 mm in diameter, are radially opened on the lower circumferential wall of each main shaft. They are evenly distributed circumferentially, with an angle of 90° between adjacent grouting holes. The grouting holes 27 are connected to the grouting channels inside the main shaft. After being pressurized by the high-pressure grouting pump 23, the curing agent solution flows sequentially through the flow control valve 24, the grouting pipeline 26, and the grouting channels inside the main shaft, and is finally evenly injected into the soil of the mixing zone 37 through the grouting holes 27.

[0049] See Figure 5 The electrical control system 28 is based on a PLC programmable logic controller and includes a PLC controller 29, a touch screen human-machine interface, servo drivers, a sensor signal acquisition module 30, and a remote communication module.

[0050] The PLC controller 29 is a Siemens S7-1200 series, CPU model 1214C DC / DC / DC, with a main frequency of 100MHz, 125KB program memory, and 1MB data memory. It is configured with 16 DC24V digital input modules, 16 DC24V digital output modules, 8 4~20mA analog input modules, and 4 4~20mA analog output modules. The PLC sends pulse direction and enable signals to the servo driver through the digital output modules, sends control signals to the high-pressure grouting pump 23 and flow control valve 24 through the analog output modules, and receives feedback signals from the pressure sensor 25 and flow sensor through the analog input modules.

[0051] The touchscreen is a 10-inch Weintek capacitive touchscreen with a resolution of 1024×600. It communicates with the PLC controller 29 via an Ethernet interface using the Modbus TCP protocol. The touchscreen displays screens for setting construction parameters, monitoring equipment operation, displaying fault alarms, and providing data reports. Operators can set parameters such as vertical feed speed, horizontal reciprocating frequency, grouting pressure, and grouting flow rate, and can view the real-time operating status of each piece of equipment and sensor data.

[0052] The servo drives are Panasonic A6 series, totaling three units, driving the vertical feed drive motor 6, the first servo motor 12, and the second servo motor 13, respectively. Each drive is connected to the servo motor via a power cable and to the motor via an encoder cable, with an integrated absolute encoder. The drive receives speed commands from the PLC through a pulse direction interface, and has built-in position and speed closed-loop controls to ensure speed and position accuracy. The drive communicates with the PLC via an RS485 bus using the Modbus RTU protocol.

[0053] The sensor signal acquisition module 30 is integrated into the analog input module of the PLC, acquiring parameters such as grouting pressure (pressure sensor 25), grouting flow rate (electromagnetic flowmeter on the grouting pipeline), vertical feed speed (rotary encoder on the ball screw drive pair 5), reciprocating frequency (servo drive encoder feedback), and amplitude (displacement sensor on the slider 16) in real time. The acquired data is processed by the PLC controller 29 and displayed in real time on the touch screen. The PLC controller 29 compares the measured grouting pressure value fed back by the sensor signal acquisition module 30 with the set value, and uses a PID algorithm to output a 4~20mA control signal to adjust the opening of the flow control valve 24. When the grouting pressure deviation exceeds the set value ±5%, the swashplate angle of the high-pressure grouting pump 23 is adjusted to change the discharge rate. When the vertical feed speed deviation exceeds the set value ±5%, the PLC controller 29 adjusts the speed of the feed drive motor 6 to correct it.

[0054] The remote communication module adopts a 4G wireless communication module, supports LTE-TDD / LTE-FDD standards, has a built-in SIM card slot, and is connected to the PLC controller 29 via an RS232 interface. It uploads key parameters such as pile number, pile depth, grouting volume, and construction time during the construction process to the cloud server in real time for remote monitoring, storage, and traceability by the smart construction site management platform.

[0055] See Figure 1 and Figure 6The portal steel frame 2 has a walking mechanism 31 at its bottom, comprising four sets of steel walking wheels and a traction connection device. Each set of walking wheels is mounted below the bearing plate of the hydraulic outrigger 3, with a wheel diameter of 400mm, a rim width of 150mm, and a wheel body made of ZG45 cast steel with a surface hardening hardness of HRC40~45. The walking wheels are connected to the mounting base via axles, and the mounting base is bolted to the bottom of the cylinder of the hydraulic outrigger 3. The first two sets of walking wheels are directional wheels, and the last two sets are swivel wheels (with steering mechanisms). The traction connection device is located at the front end of the frame assembly 1 and is in the form of a towing hook, used to connect to the towing vehicle. When moving equipment, the hydraulic outrigger 3 first grounds the walking wheels and raises the portal steel frame 2, which is then towed to the next pile position by the towing vehicle.

[0056] The following is combined Figures 1 to 8 This describes the specific steps for continuous forming of deep mixing piles using the aforementioned device. The construction parameters for each step can be adjusted in real time according to the site soil type and design requirements.

[0057] Step 1: Pre-construction preparation and site leveling. Use an excavator in conjunction with manual labor to clear weeds, tree roots, and construction debris from the site. Break up hard obstacles such as concrete blocks and large-diameter stones with a hydraulic breaker before removal. After clearing, use a bulldozer for rough leveling, followed by a grader for fine leveling, ensuring the site flatness error is controlled within ±50mm. Dig drainage ditches around the site, 300mm wide and 400mm deep, with a 0.3% slope at the bottom. Apply a 20mm thick layer of cement mortar to the inner walls to prevent water accumulation during construction.

[0058] Lay out the pile positions according to the design drawings. Use a total station for positioning, with an angle measurement accuracy of 2″ and a distance measurement accuracy of ±(2mm+2×10). -6 •D (D is the measurement distance). The instrument is set up on the measurement control point. After determining the instrument position using the resection method, the coordinates of the pile positions are laid out point by point. The pile position positioning error is controlled within ±10mm. A marker pile is driven into each pile position. The marker pile is made of HRB400 steel bar with a diameter of 12mm, 300mm in length, driven 200mm into the ground and 100mm exposed. The top of the pile is painted red for identification.

[0059] Install and debug the construction equipment. Move the frame assembly 1 to the starting position of the construction via the walking mechanism 31. Operate the hydraulic outriggers 3 to level the portal steel structure frame 2. Use a frame level to monitor the levelness error, which should not exceed 0.2°. Then, conduct no-load test runs on the vertical feed system, the dual-shaft horizontal reciprocating mixing system 8, and the curing agent synchronous injection system 21. Before the test run, check the tightness of each connecting bolt, the lubrication of each lubrication point, and the electrical wiring. The no-load test run should last for no less than 30 minutes. During this period, observe whether there is any abnormal noise in each system (noise value not exceeding 85dB(A)), whether there is any leakage (no leakage at each joint of the hydraulic system and grouting system), and whether the operation is smooth (the sliding mounting frame 7 moves up and down along the vertical linear guide rail 4 without jamming, and the slider 16 moves back and forth along the horizontal guide rail 17 without crawling). Simultaneously calibrate the parameters of the electronic control system 28: input 4mA and 20mA standard current signals to the sensor signal acquisition module 30 using a standard signal generator, check whether the pressure, flow rate, displacement and other values ​​displayed on the touch screen are consistent with the standard values, and perform zero-point and full-scale calibration when the deviation exceeds the standard to ensure that the measurement accuracy of each sensor meets the requirements.

[0060] Step 2, Preparation of the curing agent solution. The curing agent solution is prepared according to the soil type and the designed pile strength. This embodiment takes a typical soft soil foundation as an example. The mass percentages of each component in the curing agent solution are as follows: ordinary Portland cement P.O42.5 grade 35%, S95 grade slag powder 28%, Class F II fly ash 22%, water glass with a modulus of 3.2 12%, polycarboxylate-based high-efficiency water-reducing agent (powder, water reduction rate not less than 25%) 2.5%, and water 0.5%, with the sum of the mass percentages of all components being 100%. In this formulation, water glass acts as a settling promoter and activates the pozzolanic activity of the slag powder, thereby improving the early strength of the cement-soil mixture.

[0061] During preparation, first add the measured water, water-reducing agent, and water glass to the curing agent mixing tank 22, and start the mixer at 60 rpm for 3 minutes to fully dissolve and disperse the water-reducing agent and water glass. Then add the measured cement, slag powder, and fly ash, and continue mixing at 60 rpm for 15 minutes. After mixing, test the density and viscosity of the curing agent solution. The density is measured using a mud hydrometer, with a target control of 1.42 g / cm³. 3 ~1.48g / cm 3 Viscosity was measured using a rotational viscometer at 20°C, with a target range of 120 mPa·s to 180 mPa·s. If the density was too high, a small amount of water was added (no more than 1% of the total mass each time); if it was too low, a small amount of cement was added (no more than 0.5% of the total mass each time). After each adjustment, the solution was re-stirred for 5 minutes and then retested. The prepared curing agent solution should be used within 2 hours. If used after 2 hours, the viscosity must be retested, and any solution exceeding 180 mPa·s should be discarded. During construction, the stirring motor of the curing agent mixing tank 22 should be continuously running.

[0062] Step 3, Equipment Positioning and Centering. The equipment is pulled to the pile location to be constructed via the traveling mechanism 31. The equipment position and orientation are adjusted according to the location of the ground marker piles, ensuring that the central axes of the first mixing shaft 9 and the second mixing shaft 10 are aligned with the center of the designed pile location. Centering is assisted by a laser centering device on the frame assembly 1, mounted on the sliding mounting frame 7. The laser centering device's optical axis is parallel to the central axis of the dual-axis mixing shafts. The centering accuracy is judged by observing the overlap between the laser spot and the center of the pile location marker pile; the centering error is controlled within ±5mm.

[0063] After centering, readjust the hydraulic outriggers 3 to confirm that the levelness error of the portal steel structure frame 2 is no greater than 0.2°. The sliding mounting bracket 7 is adjusted to its initial position via the electrical control system 28, ensuring that the lower ends of the first mixing shaft 9 and the second mixing shaft 10 are 200mm above the ground. The grouting pipe 26 of the curing agent synchronous injection system 21 is connected to the grouting interfaces of the first mixing shaft 9 and the second mixing shaft 10 using quick connectors and fitted with wire clamps to prevent detachment, ensuring no leakage under grouting pressure. The mixing motor of the curing agent mixing tank 22 is turned on to ensure continuous mixing.

[0064] Step 4, dual-shaft reciprocating mixing and synchronous grouting sinking, such as Figure 7 As shown. The first servo motor 12 and the second servo motor 13 of the dual-shaft horizontal reciprocating mixing system 8 are started by the electronic control system 28. The horizontal reciprocating frequency is set to 8.1Hz to 9.0Hz (8.1Hz for silty soil, 9.0Hz for silty clay, and 8.5Hz for general soft soil) on the touch screen, and the amplitude is fixed at 180mm. The two servo motors run synchronously under the control of the PLC controller 29, driving the first mixing spindle 9 and the second mixing spindle 10 to perform synchronous horizontal reciprocating linear motion along the horizontal guide rail 17 through the crank-slider mechanism.

[0065] Simultaneously, the feed drive motor 6 of the vertical feed system is started, and the vertical feed speed is set from 0.76 m / min to 0.84 m / min on the touch screen (the harder the soil, the smaller the value; the softer the soil, the larger the value). After being reduced in speed by the planetary gear reducer, the feed drive motor 6 drives the ball screw transmission pair 5 to rotate. The screw nut seat drives the sliding mounting frame 7 to move downward along the vertical linear guide rail 4. The sliding mounting frame 7, along with the dual-shaft horizontal reciprocating mixing system 8, is fed downward as a whole.

[0066] While the first mixing shaft 9 and the second mixing shaft 10 move downwards, the high-pressure grouting pump 23 of the curing agent synchronous injection system 21 is activated via the electrical control system 28. The grouting pressure is set to 3.0 MPa to 3.4 MPa (lower value for high soil permeability, higher value for low permeability), and the grouting flow rate is set to 42 L / min to 48 L / min (calculated based on the vertical feed speed and designed pile diameter to ensure that the grouting volume per unit depth meets the design requirements). After being pressurized by the high-pressure grouting pump 23, the curing agent solution flows through the flow control valve 24, the grouting pipeline 26, and the grouting channel inside the shaft, and is evenly injected into the soil around the shafts through the grouting holes 27 at the lower ends of the first mixing shaft 9 and the second mixing shaft 10.

[0067] Under the combined action of the horizontal reciprocating motion and the vertical downward motion of the mixing shaft, the in-situ soil is cut and broken by the mixing blades 19. At the same time, the curing agent solution continuously injected from the grouting hole 27 is uniformly mixed with the broken soil particles under the repeated shearing and mixing of the mixing blades 19, forming a cement-soil mixture. Because the mixing blade assemblies 18 on the first mixing shaft 9 and the second mixing shaft 10 are staggered and the two shafts move horizontally in sync, the full-section mixing area 37 between the two shafts is completely covered by the movement trajectory of the mixing blades 19, with no mixing blind spots.

[0068] During the mixing process, the sensor signal acquisition module 30 of the electronic control system 28 monitors the vertical feed speed (rotary encoder on the ball screw drive pair 5), horizontal reciprocating frequency (servo drive encoder feedback), grouting pressure (pressure sensor 25), and grouting flow rate (electromagnetic flow meter) in real time. When a parameter deviates from the set value's allowable range (vertical feed speed deviation not exceeding ±5%, reciprocating frequency deviation not exceeding ±2%, grouting pressure deviation not exceeding ±3%, and grouting flow rate deviation not exceeding ±3%), the PLC controller 29 automatically performs closed-loop adjustment: adjusting the speed of the feed drive motor 6 to correct the vertical feed speed, and adjusting the swashplate angle of the high-pressure grouting pump 23 or the opening of the flow control valve 24 to correct the grouting pressure and flow rate.

[0069] When the first mixing spindle 9 and the second mixing spindle 10 sink to the designed pile bottom elevation 36, the encoder feedback of the feed drive motor 6 (combined with the ball screw lead to calculate the sinking distance) or the displacement sensor on the sliding mounting bracket 7 gives the positioning signal, and the PLC controller 29 automatically stops the vertical feed.

[0070] Step 5: Strengthen mixing and grouting at the bottom of the pile. After the first mixing shaft 9 and the second mixing shaft 10 are lowered to the designed pile bottom elevation of 36, the dual-shaft horizontal reciprocating mixing system 8 is kept running (reciprocating frequency remains unchanged). The vertical feed speed is adjusted to 0.2 m / min by the electrical control system 28, and the sliding mounting frame 7 is controlled to lift the mixing shaft upward by 1.2 m, and then lower it back to the pile bottom elevation of 36 at the same speed of 0.2 m / min. This lifting and lowering is repeated twice.

[0071] During the enhanced mixing process, the electrical control system 28 increases the grouting pressure to 4.3MPa to 4.7MPa and the grouting flow rate to 62L / min to 68L / min to replenish grout in the pile bottom area. Enhanced mixing and grout replenishment are to ensure the uniformity and density of the cement-soil mixture at the pile bottom, and to avoid uneven mixing and insufficient grout distribution that may occur when the mixing spindle starts and stops at the pile bottom, thereby preventing sediment and insufficient strength at the pile bottom.

[0072] After the enhanced mixing and grouting are completed, the electrical control system 28 adjusts the grouting pressure back to 3.0MPa to 3.4MPa during the sinking stage, and the grouting flow rate back to 42L / min to 48L / min.

[0073] Step 6: Lifting and Continuous Multi-Pile Forming. After the single pile sinking, mixing, and bottom reinforcement are completed, the dual-axis horizontal reciprocating mixing system 8 is kept running (reciprocating frequency remains unchanged). The vertical feeding system is activated by the electrical control system 28 to lift the pile upwards at a speed of 1.2 m / min. During the lifting process, the curing agent synchronous injection system 21 continues to operate, with the grouting pressure adjusted to 2.7 MPa to 3.0 MPa and the grouting flow rate adjusted to 33 L / min to 37 L / min. The grouting volume during the lifting stage is appropriately reduced compared to the sinking stage to compensate for the uneven grout distribution that may be caused by the grout's own weight sinking in the upper part of the pile, while avoiding excessive grouting that would lead to waste and reduced strength in the upper part of the pile.

[0074] When the lower ends of the first mixing shaft 9 and the second mixing shaft 10 are raised to 0.5m above the ground, the displacement sensor gives a positioning signal, and the PLC controller 29 automatically stops the vertical lifting and shuts down the high-pressure grouting pump 23.

[0075] After a single pile is completed, the portal steel frame 2 is moved as a whole to the next adjacent pile location via the traveling mechanism 31. During the movement, the electrical control system 28 controls the first servo motor 12 and the second servo motor 13 to operate at a low speed (corresponding to a reciprocating frequency of 2Hz to 3Hz), so that the first mixing shaft 9 and the second mixing shaft 10 maintain a slow horizontal reciprocating motion to prevent the cement-soil mixture adhering to the mixing blades 19 from solidifying and caking. After moving to the next pile location, steps 3 to 5 are repeated to complete the next pile.

[0076] This cyclical process enables continuous operation at multiple pile locations. The construction interval between adjacent piles is controlled at 30 to 40 minutes to ensure that the overlap between adjacent piles is completed before the initial setting of the cement-soil mixture. See also Figure 6 The center-to-center distance between adjacent piles is 1.1m. The design diameter of the cement-soil pile 32 is 1.3m. The overlap area 34 between adjacent cement-soil piles 33 is 200mm wide (the difference between the center-to-center distance of 1.1m and the pile diameter of 1.3m is the overlap width). After continuous pile driving, a seamless cement-soil reinforced wall is formed.

[0077] Step 7: Simultaneous curing and shaping of the pile body. During the mixing process, the cementitious materials such as ordinary silicate cement and slag powder in the curing agent solution injected into the soil undergo a hydration reaction with the moisture in the soil. Due to the horizontal reciprocating shearing of the mixing shaft, the curing agent and soil are fully mixed within the full-section mixing zone 37. The hydration reaction is fully launched during the mixing process, and the cement-soil mixture begins to gradually harden as soon as the mixing is completed, achieving simultaneous mixing and curing. The completed pile body reaches more than 70% of the design strength within 24 hours and 100% of the design strength within 28 days.

[0078] After construction, the pile quality was tested according to the "Technical Specification for Testing of Building Foundations" JGJ 340-2015. The low-strain reflected wave method was used to test the pile integrity, using an RS-1616K(S) type pile dynamic testing instrument with a sampling frequency of 24kHz and 1024 sampling points. The core drilling method was used to test the pile strength and uniformity, using an HZ-200 type rock core drill with a drill bit diameter of 101mm. The extracted core samples were processed into standard specimens with a height-to-diameter ratio of 2:1 and subjected to compressive strength tests on a universal testing machine. Evaluation criteria: A pile with an integrity coefficient of not less than 0.95 is classified as a Class I intact pile, free from defects such as broken piles, reduced diameter, and segregation; the 28-day compressive strength is not lower than the design strength grade.

[0079] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0080] Example 1: Coastal soft soil foundation.

[0081] Geological survey data: Natural moisture content 58.3%, natural density 1.62 g / cm³ 3 Porosity 1.62, liquid limit 48.5%, plastic limit 25.3%, compressibility coefficient 0.72 MPa -1The cohesion is 12.3 kPa, and the internal friction angle is 4.5°. The designed pile diameter is 1.3 m, the effective pile length is 7.6 m (from 0.4 m below ground to 8.0 m underground), the pile bottom elevation is 8.0 m underground, the pile center-to-center spacing is 1.1 m, the overlap width is 200 mm, and the design 28-day compressive strength is not less than 3.0 MPa. Site leveling and pile location layout are carried out according to step 1. The curing agent solution is prepared according to step 2, with a density of 1.45 g / cm³. 3 Viscosity 150 mPa·s. Position and align according to step 3. Construction parameters: horizontal reciprocating frequency 8.5 Hz, amplitude 180 mm, vertical sinking speed 0.8 m / min, grouting pressure 3.2 MPa, flow rate 45 L / min during sinking stage, lifting speed 0.2 m / min, 2 reciprocations during pile bottom strengthening stage, grouting pressure 4.5 MPa, flow rate 65 L / min during lifting stage, speed 1.2 m / min, grouting pressure 2.8 MPa, flow rate 35 L / min during lifting stage. Complete a single pile according to steps 4 to 6. The main shaft sinks from the initial position to the pile bottom in approximately 10.3 min, strengthening takes approximately 12 min, lifting takes approximately 6.3 min, totaling approximately 34 min including auxiliary operations. The interval between adjacent piles is 34 min. Test results: integrity coefficient 0.96, Class I pile; 7-day compressive strength 2.91 MPa, 28-day compressive strength 3.24 MPa; core sample continuous and intact, no broken piles or diameter reduction, no leakage at pile overlaps. A single unit can complete 21 piles in 12 hours of operation per day.

[0082] Example 2: Inland lacustrine soft soil foundation. Moisture content 52.7%, density 1.68 g / cm³. 3 Porosity 1.48, liquid limit 46.2%, plastic limit 24.8%, compressibility coefficient 0.65 MPa -1 The cohesion was 14.5 kPa, and the internal friction angle was 5.2°. The designed pile diameter was 1.3 m, the effective pile length was 7.8 m, the pile bottom elevation was 8.2 m below ground, the pile center-to-center spacing was 1.1 m, the overlap width was 200 mm, and the designed 28-day strength was not less than 3.0 MPa. Construction parameters: reciprocating frequency 8.2 Hz, sinking speed 0.77 m / min, sinking grouting pressure 3.1 MPa, flow rate 43 L / min, replenishment grouting pressure 4.4 MPa, flow rate 63 L / min, lifting grouting pressure 2.7 MPa, flow rate 34 L / min, and the rest were the same as in Example 1. Test results: integrity coefficient 0.97; 7-day strength 2.87 MPa, 28-day strength 3.18 MPa; no sediment at the pile bottom. 20 piles were completed per day.

[0083] Example 3: Soft soil foundation in a river valley.

[0084] Moisture content: 61.2%, density: 1.58 g / cm³ 3 Porosity 1.68, liquid limit 50.1%, plastic limit 26.2%, compressibility coefficient 0.78 MPa -1The piles exhibited a cohesion of 10.8 kPa and an internal friction angle of 3.8°. The designed pile diameter was 1.3 m, the effective pile length was 8.0 m, the pile bottom elevation was 8.4 m below ground, the pile center-to-center spacing was 1.1 m, the overlap width was 200 mm, and the designed 28-day strength was no less than 3.0 MPa. Construction parameters included: reciprocating frequency 8.8 Hz, sinking speed 0.82 m / min, sinking grouting pressure 3.3 MPa, flow rate 47 L / min, supplementary grouting pressure 4.6 MPa, flow rate 67 L / min, and lifting grouting pressure 2.9 MPa, flow rate 36 L / min. Test results showed an integrity coefficient of 0.95; 7-day strength 2.83 MPa, 28-day strength 3.12 MPa; uniform cross-section with no localized loosening. 19 piles were completed in one day.

[0085] Example 4: Soft soil foundation in urban low-lying areas.

[0086] Moisture content 55.1%, density 1.65 g / cm³ 3 Porosity 1.53, liquid limit 47.3%, plastic limit 25.0%, compressibility coefficient 0.69 MPa -1 The pile has a cohesion of 13.6 kPa and an internal friction angle of 4.8°. The designed pile diameter is 1.3 m, the effective pile length is 7.4 m, the pile bottom elevation is 7.8 m below ground, the pile center-to-center spacing is 1.1 m, the overlap width is 200 mm, and the designed 28-day strength is not less than 3.0 MPa. Construction parameters: reciprocating frequency 8.4 Hz, sinking speed 0.79 m / min, sinking grouting pressure 3.2 MPa, flow rate 44 L / min, replenishment grouting pressure 4.5 MPa, flow rate 64 L / min, lifting grouting pressure 2.8 MPa, flow rate 35 L / min. Test results: integrity coefficient 0.98; 7-day strength 2.94 MPa, 28-day strength 3.27 MPa; small strength fluctuation from pile top to lower pile body (standard deviation ≤ 0.15 MPa); permeability coefficient ≤ 1 × 10⁻⁶. -7 cm / s. 22 piles were completed in one day.

[0087] Example 5: Transformation of soft soil foundation in tidal flats.

[0088] Moisture content: 63.5%, density: 1.56 g / cm³ 3 Porosity 1.72, liquid limit 51.2%, plastic limit 26.8%, compressibility coefficient 0.81 MPa -1The piles exhibited a cohesion of 9.6 kPa and an internal friction angle of 3.2°. The designed pile diameter was 1.3 m, with an effective pile length of 8.2 m, a pile bottom elevation of 8.6 m underground, a pile center-to-center spacing of 1.1 m, an overlap width of 200 mm, and a design 28-day strength of no less than 3.0 MPa. Construction parameters included: reciprocating frequency of 9.0 Hz, sinking speed of 0.84 m / min, sinking grouting pressure of 3.4 MPa and flow rate of 48 L / min, supplementary grouting pressure of 4.7 MPa and flow rate of 68 L / min, and lifting grouting pressure of 3.0 MPa and flow rate of 37 L / min. Test results showed an integrity coefficient of 0.95; 7-day strength of 2.79 MPa (above 70% of design strength), and 28-day strength of 3.08 MPa (meeting design requirements); stable curing effect below 8 m underground with no diameter reduction. 18 piles were completed per day.

[0089] Example 6: Backfilling soft soil foundation in farmland.

[0090] Moisture content 49.6%, density 1.70 g / cm³ 3 Porosity 1.42, liquid limit 44.8%, plastic limit 24.1%, compressibility coefficient 0.61 MPa -1 The piles exhibited a cohesion of 15.8 kPa and an internal friction angle of 5.8°. The designed pile diameter was 1.3 m, the effective pile length was 7.2 m, the pile bottom elevation was 7.6 m below ground, the pile center-to-center spacing was 1.1 m, the overlap width was 200 mm, and the designed 28-day strength was no less than 3.0 MPa. Construction parameters included: reciprocating frequency 8.1 Hz, sinking speed 0.76 m / min, sinking grouting pressure 3.0 MPa, flow rate 42 L / min, supplementary grouting pressure 4.3 MPa, flow rate 62 L / min, and lifting grouting pressure 2.7 MPa, flow rate 33 L / min. Test results showed an integrity coefficient of 0.98; 7-day strength 2.98 MPa, 28-day strength 3.31 MPa; the core sample was dense with few voids and cracks. 23 piles were completed in one day.

[0091] Example 7: Road reconstruction and expansion on soft soil foundation.

[0092] Moisture content 56.8%, density 1.63 g / cm³ 3 Porosity 1.58, liquid limit 48.9%, plastic limit 25.6%, compressibility coefficient 0.70 MPa -1The piles exhibited a cohesion of 11.9 kPa and an internal friction angle of 4.3°. The designed pile diameter was 1.3 m, the effective pile length was 7.7 m, the pile bottom elevation was 8.1 m below ground, the pile center-to-center spacing was 1.1 m, the overlap width was 200 mm, and the designed 28-day strength was no less than 3.0 MPa. Construction parameters included: reciprocating frequency 8.6 Hz, sinking speed 0.80 m / min, sinking grouting pressure 3.2 MPa, flow rate 45 L / min, supplementary grouting pressure 4.5 MPa, flow rate 65 L / min, and lifting grouting pressure 2.8 MPa, flow rate 35 L / min. Test results showed an integrity coefficient of 0.96; 7-day strength 2.90 MPa, 28-day strength 3.21 MPa; the core sample from the overlap area was continuous and firmly bonded. 20 piles were completed per day.

[0093] Example 8: Low-lying soft soil foundation in an industrial park.

[0094] Moisture content 59.4%, density 1.60 g / cm³ 3 Porosity 1.64, liquid limit 49.6%, plastic limit 25.9%, compressibility coefficient 0.75 MPa -1 The cohesion was 11.2 kPa, and the internal friction angle was 4.0°. The designed pile diameter was 1.3 m, the effective pile length was 7.9 m, the pile bottom elevation was 8.3 m below ground, the pile center-to-center spacing was 1.1 m, the overlap width was 200 mm, and the designed 28-day strength was not less than 3.0 MPa. Construction parameters: reciprocating frequency 8.7 Hz, sinking speed 0.81 m / min, sinking grouting pressure 3.3 MPa, flow rate 46 L / min, replenishment grouting pressure 4.6 MPa, flow rate 66 L / min, and lifting grouting pressure 2.9 MPa, flow rate 36 L / min. Test results: integrity coefficient 0.96; 7-day strength 2.85 MPa, 28-day strength 3.15 MPa; the soil and curing agent were evenly distributed in the core sample cross-section, with no weak interlayers caused by poor mixing. 19 piles were completed in one day.

[0095] The results from eight different field implementations demonstrate that this biaxial reciprocating mixing deep mixing pile continuous forming technology exhibits excellent construction effects and pile quality in various soft soil foundation scenarios. Regarding pile integrity, the pile integrity coefficient in all implementation cases remained at 0.95 or higher, proving that the biaxial horizontal reciprocating shear mixing mode completely solves the mixing blind zone problem present in traditional rotary mixing piles. The soil and solidifier can achieve uniform mixing across the entire cross-section, effectively avoiding common quality defects such as pile breakage, diameter reduction, and localized loosening. From a mechanical performance perspective, in soft soil foundations with different moisture contents and compressibility coefficients, the 7-day compressive strength of the piles ranged from 2.79 MPa to 2.98 MPa, all reaching over 70% of the design strength. The 28-day compressive strength remained stable between 3.08 MPa and 3.31 MPa, fully meeting the engineering design requirements. This demonstrates the advantage of this technology in achieving simultaneous mixing and curing. The hydration reaction of the curing agent continues during the mixing process, eliminating the need to wait for the tools to be removed before hardening, thus shortening the curing cycle and ensuring the stability of pile strength development. Higher soil moisture content and compressibility coefficients resulted in slightly lower early pile strength, but the final 28-day strength still met the requirements, indicating that this technology has good adaptability to soft soils with high moisture content and high compressibility. In terms of construction efficiency, this technology breaks away from the traditional single-hole, pile-by-pile construction model. Relying on continuous operation, a single unit can complete 18 to 23 piles per day, significantly improving efficiency compared to traditional mixing pile construction. Furthermore, the construction interval between adjacent piles is controlled within 30 to 40 minutes, the overlap width between piles is consistently up to standard, and the overlap areas are seamless and leak-free. The overall reinforced structure formed by continuous pile construction exhibits excellent integrity and seepage prevention performance. Overall, this technology surpasses traditional rotary mixing pile technology in multiple dimensions, including pile quality, construction efficiency, site adaptability, and structural integrity. It can be widely applied to various soft soil foundation reinforcement and seepage prevention projects in coastal, lacustrine, river valley, and backfill areas, demonstrating high practicality and promotional value.

[0096] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0097] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0098] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixation," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances. When a component is said to be "fixed to" another component, it can be directly on the other component or there may be an intervening component. When a component is considered to be "connected" to another component, it can be directly connected to the other component or there may be an intervening component. When a component is considered to be "set on" another component, it can be directly set on the other component or there may be an intervening component.

[0099] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0100] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0101] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0102] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Those skilled in the art can readily implement the present invention based on the accompanying drawings and the above description. However, any modifications, alterations, or variations made by those skilled in the art without departing from the scope of the present invention, utilizing the disclosed technical content, are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, or variations made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the present invention.

Claims

1. A dual-axis reciprocating mixing type deep mixing pile continuous forming device, characterized in that, It includes a frame assembly (1), a vertical feeding system mounted on the frame assembly (1), a dual-shaft horizontal reciprocating mixing system (8) driven to rise and fall by the vertical feeding system, and a curing agent synchronous injection system (21) that supplies material to the dual-shaft horizontal reciprocating mixing system (8). The dual-shaft horizontal reciprocating stirring system (8) includes: A horizontal guide rail (17) is slidably mounted on the vertical feed system; The first stirring spindle (9) and the second stirring spindle are arranged in parallel on the horizontal guide rail (17); The horizontal reciprocating drive mechanism (11) is connected to the first stirring spindle (9) and the second stirring spindle respectively, and is used to drive the first stirring spindle (9) and the second stirring spindle to make synchronous horizontal reciprocating linear motion along the horizontal guide rail (17); A stirring paddle assembly (18) is disposed on the first stirring spindle (9) and the second stirring spindle, and the stirring paddle assemblies (18) on the first stirring spindle (9) and the second stirring spindle are arranged in an alternating manner so that the two form an overlapping full-section stirring area (37) during horizontal reciprocating motion. The curing agent synchronous injection system (21) includes a grouting pipeline (26), which extends to the lower ends of the first stirring shaft (9) and the second stirring shaft, and has grouting holes (27) that communicate with the grouting pipeline (26) radially at the lower ends of the first stirring shaft (9) and the second stirring shaft.

2. The dual-axis reciprocating mixing type deep mixing pile continuous forming device according to claim 1, characterized in that, The vertical feed system includes a vertical linear guide (4), a ball screw drive pair (5), a feed drive motor (6), and a sliding mounting bracket (7) mounted on the frame assembly (1). The sliding mounting bracket (7) is slidably connected to the vertical linear guide (4) via a slider and connected to the ball screw drive pair (5). The horizontal guide (17) is fixed on the sliding mounting bracket (7).

3. The dual-axis reciprocating mixing type deep mixing pile continuous forming device according to claim 1, characterized in that, The horizontal reciprocating drive mechanism (11) adopts a crank-slider mechanism with dual servo motors driving synchronously, including a first servo motor (12), a second servo motor (13), a crank disk (14) connected to the output shafts of the first servo motor (12) and the second servo motor (13) respectively, a crank pin (15) set on the crank disk (14) and a slider (16) cooperating with the crank pin (15); the upper ends of the first stirring spindle (9) and the second stirring spindle are fixedly connected to the corresponding sliders (16).

4. The dual-axis reciprocating mixing type deep mixing pile continuous forming device according to claim 1, characterized in that, The stirring paddle assembly (18) is arranged at equal intervals along the axial direction of the first stirring main shaft (9) and the second stirring main shaft. Multiple sets of the stirring paddle assembly (18) are arranged on a single main shaft. Each set of the stirring paddle assembly (18) includes symmetrically arranged stirring blades (19). The soil-facing surface of the stirring blades (19) is provided with wear-resistant grooves, and the stirring blades (19) are arranged at a 15° angle with the axis of the main shaft. The bottom ends of the first stirring main shaft (9) and the second stirring main shaft are both provided with sealing and protective components.

5. The dual-axis reciprocating mixing type deep mixing pile continuous forming device according to claim 1, characterized in that, The curing agent synchronous injection system (21) also includes a curing agent mixing tank (22), a high-pressure grouting pump (23), a flow control valve (24), and a pressure sensor (25); the device also includes an electrical control system (28), which includes a PLC controller (29) and a sensor signal acquisition module (30) for coordinated control of the vertical feeding system, the dual-axis horizontal reciprocating mixing system (8), and the curing agent synchronous injection system (21).

6. A method for continuous forming of deep mixing piles using the apparatus described in any one of claims 1 to 5, characterized in that, Includes the following stages: Equipment placement and alignment stage: Move the molding device to the pile location to be constructed, so that the central axis of the first mixing shaft (9) and the second mixing shaft are aligned with the center of the designed pile location; Dual-shaft reciprocating stirring and synchronous grouting sinking stage: Start the horizontal reciprocating drive mechanism (11) to drive the first stirring main shaft (9) and the second stirring main shaft to perform synchronous horizontal reciprocating linear motion; The vertical feed system is started to drive the main shaft to move downward, and during the sinking process, the curing agent solution is continuously injected into the soil through the grouting hole (27) so that the in-situ soil is uniformly mixed with the curing agent across the entire cross section under the horizontal reciprocating shearing action. Strengthening mixing and grouting stage at the bottom of the pile: After the main shaft sinks to the designed pile bottom elevation (36), it maintains a horizontal reciprocating motion state, controls the main shaft to perform multiple reciprocating rises and falls within the predetermined height range, and increases the grouting pressure and grouting flow rate during the rise and fall process to perform bottom grouting; Lifting and shifting and continuous forming of multiple pile positions: control the main shaft to lift upward and keep grouting synchronously during the lifting process. When the main shaft is lifted to a preset position at a distance of (35) from the ground, stop grouting. While maintaining the horizontal reciprocating motion of the main shaft, move the entire device to the next adjacent pile position through the walking mechanism (31) and repeat the above construction actions to form an overlapping area (34) between adjacent cement-soil piles (33) to achieve continuous forming of multiple pile positions.

7. The method for continuous forming of deep mixing piles according to claim 6, characterized in that, During the biaxial reciprocating stirring and synchronous grouting sinking stage, the reciprocating frequency of the horizontal reciprocating drive mechanism (11) is set to 8.1Hz-9.0Hz, and the amplitude is set to 180mm.

8. The method for continuous forming of deep mixing piles according to claim 6, characterized in that, During the biaxial reciprocating stirring and synchronous grouting sinking stage, the downward movement speed of the vertical feeding system is set to 0.76m / min-0.84m / min, the grouting pressure of the curing agent solution is set to 3.0MPa-3.4MPa, and the grouting flow rate is set to 42L / min-48L / min.

9. The method for continuous forming of deep mixing piles according to claim 6 or 8, characterized in that, During the bottom stirring and grouting stage of the pile body, the reciprocating lifting speed of the main shaft is adjusted to 0.2m / min, and the grouting pressure of the bottom grouting is increased to 4.3MPa-4.7MPa, and the grouting flow rate is increased to 62L / min-68L / min.

10. The method for continuous forming of deep mixing piles according to claim 6, characterized in that, Before the equipment placement and alignment stage, there is also a curing agent solution preparation stage: ordinary silicate cement, slag powder, fly ash, water glass, polycarboxylate-based high-efficiency water-reducing agent and water are added to the curing agent mixing tank (22) and mixed to prepare a solution with a density controlled at 1.42 g / cm³. 3 -1.48g / cm 3 A curing agent solution with a viscosity controlled between 120 mPa·s and 180 mPa·s.

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