An intelligent drag reduction and posture correction method for static pressure soil displacement pile construction

Abstract

This invention belongs to the field of static pressure displacement pile construction technology and discloses an intelligent drag reduction and attitude correction method for static pressure displacement pile construction. It establishes a three-dimensional digital geological model through advanced drilling, classifies and categorizes the pile's resistance in the circumferential and longitudinal directions, and employs a combination of ultrasonic vibration and high-pressure gas-liquid pulse drag reduction for different areas. No chemical lubricating slurry is used throughout the process, avoiding groundwater and soil contamination. Simultaneously, it combines attitude deviation with directional enhanced drag reduction, forming a closed-loop control system and dynamically adjusting drag reduction parameters. This reduces penetration resistance in high-resistance areas, avoids excessive drag reduction disturbing the soil, and achieves an optimal balance between drag reduction efficiency and pile bearing capacity. A precise and non-destructive correction system is constructed that coordinates drag reduction and correction depth. When a deviation warning occurs in the pile, drag reduction is first enhanced in the opposite direction of the deviation to reduce soil reaction force, creating low-resistance construction conditions for correction. Then, a graded correction strategy is implemented according to the degree of deviation.

Description

Technical Field

[0001] This invention belongs to the field of static pressure displacement pile construction technology, specifically an intelligent drag reduction and attitude correction method for static pressure displacement pile construction. Background Technology

[0002] Static pressure displacement piles are widely used in pile foundation engineering fields such as urban construction, municipal engineering, and soft soil foundation reinforcement due to their advantages of no vibration, low noise, stable pile quality, high construction efficiency, and minimal impact on the surrounding environment. During static pressure pile driving, the pile body squeezes the soil, causing shear deformation and reshaping, inevitably producing a significant soil displacement effect. On the one hand, this leads to a sharp increase in the side friction and end resistance of the pile body, making pile driving difficult and causing the pile driver load to exceed the limit. Especially in deep soft soil, alternating layers of soft and hard soil, dense silt, and sandy soil, piles are prone to not being driven into place. On the other hand, uneven distribution of circumferential resistance of the soil around the pile and abrupt changes in the hardness of the strata can easily lead to pile tilting, displacement, or even bending and fracture, seriously affecting the bearing capacity of the pile foundation and threatening the safety of the superstructure.

[0003] Existing static pressure displacement pile drag reduction technology mainly involves coating the pile body with lubricating drag-reducing agent and injecting lubricating slurry at the pile end. This type of passive overall drag reduction cannot implement differentiated control according to the spatial distribution of resistance, has low drag reduction efficiency, and the lubricating material is prone to contaminating groundwater and soil. At the same time, it cannot solve the core problem of pile body deflection caused by uneven circumferential resistance.

[0004] Existing static pressure displacement pile posture correction technologies are mostly post-correction methods, which are handled by jacking, applying reaction force, and adding piles. These methods have serious lag, are difficult and costly to correct, and are prone to causing secondary damage or even breakage to the pile body. A few real-time correction technologies only use open-loop hard correction through the hydraulic system of the pile driver, without coordination with drag reduction technology. This results in high additional stress on the pile body, high risk of pile breakage, low correction accuracy, inability to adapt to dynamic changes in the strata, and difficulty in eliminating the causes of deviation at the root.

[0005] Existing intelligent construction systems often focus on controlling a single parameter, failing to achieve real-time perception of multi-physics interaction between piles and soil, collaborative decision-making for drag reduction and correction, and dynamic optimization throughout the entire process. In complex strata, problems such as pile tilting and incomplete pile driving are prone to occur, making it impossible to meet the requirements of high-standard pile foundation engineering. Summary of the Invention

[0006] The purpose of this invention is to provide an intelligent drag reduction and attitude correction method for static pressure displacement pile construction, so as to solve one or more problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: an intelligent drag reduction and attitude correction method for static pressure displacement pile construction, comprising: Preferably, the modeling and calibration stage is as follows: By conducting advanced continuous drilling at the pile location axis, physical and mechanical parameters of various strata within the entire depth range of the pile body are obtained, including soil cohesion, internal friction angle, compression modulus, water content, and density. Combined with the overall geological survey data of the site, a three-dimensional digital stratum model for the pile location is established, dividing the soft and hard interlayers, weak interlayers, hard interlayers, dense sand layers, and other resistance-sensitive strata, and predicting high resistance areas and easily deflected strata during the pile driving process. The spatial positioning accuracy of the 3D digital stratigraphic model is controlled at 0.05m, and the vertical stratigraphic layering accuracy is 0.5m. The model is constructed in layers according to stratigraphic lithology, resistance level, sensitive layer, and easily deflected layer. Each layer can be retrieved and overlaid for analysis independently. The model data is stored in a common GIS vector format and supports seamless data docking with control terminals and cloud platforms. The physical and mechanical parameter thresholds and distribution ranges of each layer need to be marked in the model.

[0008] The precast pile body integrates a distributed fiber optic sensing unit, a circumferentially equidistant ultrasonic vibration drag reduction unit, a circumferentially equidistant high-pressure gas-liquid pulse drag reduction unit at the pile end, and a multi-directional servo hydraulic correction unit at the pile top. It completes indoor performance calibration and on-site joint debugging, establishes the mapping relationship between sensing parameters and the soil resistance around the pile and the pile body posture deviation, completes the initial zero calibration of the system, and realizes the intelligent integration of the pile body itself.

[0009] Preferably, the perception initiation phase is as follows: After the pile body is hoisted and positioned, the initial bidirectional leveling of the pile body is completed through the pile top servo correction unit to ensure that the initial verticality deviation is controlled within 0.1%. Then, the multi-dimensional sensing system built into the pile body is activated. Throughout the static pressure pile driving process, the system collects data in real time at a sampling frequency of no less than 10Hz, including the pile body's XY bidirectional verticality deviation, the full distribution of axial stress in the pile body, the circumferential side friction data of the pile body, the pile end resistance, and the distribution of soil extrusion stress around the pile. All collected data are transmitted to the edge computing control terminal in real time. The terminal dynamically updates the actual parameters of the three-dimensional geological model by combining the collected data, and identifies abrupt changes in the geological formation and abnormal trends in the pile posture in advance.

[0010] Fault determination criteria for the sensing system: Three consecutive invalid acquisitions of a single type of data, data deviation exceeding twice the acquisition accuracy, or data transmission interruption exceeding 2 seconds are all considered partial faults in the sensing system. All invalid data acquisitions or transmission interruptions exceeding 5 seconds are considered overall system faults. In the event of a partial fault, immediately suspend drag reduction and correction operations in the corresponding area, activate backup sensing points to supplement data, and recalibrate after fault resolution before resuming construction. In the event of an overall system fault, immediately stop static pressure pile driving operations, maintain the pile in its current position, and apply low load pressure. Construction can only resume after the fault is completely resolved and the entire system calibration is completed. During the fault period, any drag reduction or correction operations are prohibited.

[0011] Preferably, the resistance grading stage is as follows: Based on real-time collected data on the circumferential and longitudinal resistance of the pile, and combined with a dynamically updated geological model, the control terminal divides the pile into four quadrants along the circumference and into multiple control segments along the longitudinal direction according to the geological strata. It identifies the areas with excessive side friction and soil extrusion stress in each zone and each control segment, calculates the drag reduction requirement level for different areas, and classifies them into three categories: priority drag reduction area, conventional drag reduction area, and no drag reduction area. By using the spatial distribution data of resistance, we can determine whether the uneven circumferential resistance around the pile is the core cause of the pile's attitude deviation. We can establish a coupled correlation model between abnormal resistance distribution and the trend of pile attitude deviation, clarify the directional resistance reduction requirements needed to eliminate attitude deviation, and realize the linkage analysis between resistance reduction requirements and deviation correction requirements.

[0012] Preferably, the drag reduction control stage is as follows: The control terminal issues control commands to the drag reduction units in the corresponding areas according to the drag reduction requirements of the zones and the directional drag reduction requirements, and executes differentiated drag reduction control. For priority drag reduction zones, the ultrasonic vibration drag reduction unit of the pile body and the high-pressure gas-liquid pulse drag reduction unit at the corresponding position of the pile tip are activated simultaneously. The ultrasonic vibration causes instantaneous liquefaction of the soil around the pile, and the high-pressure gas-liquid pulse at the pile tip forms a local air curtain buffer layer to reduce the penetration resistance of the pile tip. For conventional drag reduction zones, only the low-power ultrasonic vibration drag reduction unit is activated to maintain a low resistance state. For areas without drag reduction, no drag reduction unit is activated. In response to the trend of pile posture deviation, enhanced drag reduction control is implemented in the area opposite to the deviation to reduce the stiffness and reaction force of the soil in the area in advance. During the drag reduction process, the sensing system collects drag change data in real time and dynamically adjusts the power and duration of the drag reduction unit.

[0013] Preferably, the attitude correction stage is specifically as follows: When the real-time monitored verticality deviation of the pile reaches the preset warning threshold, the control terminal first performs the reverse direction reinforcement drag reduction operation in the drag reduction control stage. After the soil resistance in the corresponding area drops to the preset safety threshold, the multi-directional servo hydraulic correction unit at the top of the pile is activated. According to the direction of the pile deviation, the amount of deviation and the stratum conditions, graded correction control is performed. For slight deviations, a low-load uniform speed correction mode is adopted, and a stable correction reaction force is continuously applied until the deviation returns to the allowable range. For medium deviations, a graded progressive correction mode is adopted, and the correction load is gradually increased. After each load is maintained, the pile posture is re-measured to gradually correct the deviation. For large deviations, a cyclic correction mode of drag reduction, correction, pressure maintenance and re-measurement is adopted. After each correction, the pressure is maintained and stabilized, and then re-measured and adjusted. During the entire process of deviation correction, the sensing system continuously collects data on the pile body attitude and stress, dynamically adjusts the magnitude, loading rate, and resistance reduction power of the deviation correction load, and controls the pile body stress within the design allowable range throughout the process until the pile body verticality returns to the allowable deviation range specified by the code and design.

[0014] Recheck and verification criteria after deviation correction: After the pile body verticality returns to the allowable deviation range, keep the deviation correction unit under low load and maintain pressure for 10 minutes. Use the built-in sensing system in the pile body and the total station to synchronously复测 the verticality deviation twice. If the verticality deviation is within the allowable range for three consecutive rechecks and the deviation fluctuation value does not exceed 0.02%, it is determined that the deviation correction is qualified; if the recheck is unqualified, restart the resistance reduction - deviation correction process. Measures for preventing and controlling pile body deviation rebound: After the pressure maintenance recheck is qualified, slowly reduce the deviation correction load at a rate of 0.05 MPa / s. After the load drops to zero,复测 the pile body verticality again. If there is a slight rebound (deviation of 0.05%), start micro-power resistance reduction in the corresponding area and apply a micro-load for deviation correction until it is qualified; if the rebound exceeds the standard (deviation > 0.05%),重新 analyze the resistance distribution and perform graded deviation correction.

[0015] Preferably, the optimization and traceability stage is specifically as follows: During the entire process of pile driving construction, the edge computing control terminal, based on the real-time collected formation parameters, resistance data, attitude data, and pile body stress data, continuously iteratively optimizes the start-up power, action duration, and zoning combination strategy of the resistance reduction unit, as well as the load level, loading rate, and deviation correction cycle parameters of the deviation correction unit through the built-in deep learning self-learning optimization algorithm. On the premise of ensuring the pile driving efficiency, achieve the optimal balance between the resistance reduction efficiency and the pile foundation bearing capacity, and the optimal balance between the deviation correction accuracy and the pile body structure safety; All the formation data, sensing and monitoring data, resistance reduction control parameters, deviation correction control parameters, and equipment operation parameters during the entire construction process are synchronously encrypted and uploaded to the cloud management platform to form a full-life cycle digital file for single-pile construction.

[0016] Preferably, the final hole verification stage is specifically as follows: When the pile body is statically pressed to the design elevation, stop the static penetration operation, complete the multi-parameter verification of the final hole through the built-in sensing system in the pile body, synchronously复测 the final verticality of the pile body in the XY directions, the stress distribution of the entire pile section, the rebound stress of the surrounding soil of the pile, and the depth of the pile tip embedded in the stable formation. Combine the monitoring data and formation model during the entire construction process, and predict the ultimate vertical bearing capacity of the single pile through the built-in bearing capacity prediction model; The continuous monitoring time for the rebound stress of the soil around the pile shall not be less than 15 minutes, and stress data shall be collected once every 1 minute. The stability judgment criteria are: the fluctuation value of the rebound stress within 10 minutes shall not exceed 0.5 kPa, and the stress shall not have a continuous upward or downward trend. The rebound stress of the soil around the pile shall be judged to be stable. If the stress fluctuation exceeds the standard or shows a trend change within the monitoring time, the monitoring time shall be extended to 30 minutes. If it is still unstable, the cause of soil disturbance shall be analyzed. If necessary, the stress release of the soil shall be assisted by micro-power drag reduction until the stress stabilizes.

[0017] After confirming that all indicators meet the design and specification requirements, shut down all sensing, drag reduction, and correction units, and complete the recovery and resetting calibration of the reusable core unit inside the pile body. If the final hole verification reveals that the indicators do not meet the standards, a final fine-tuning and correction system and supplementary static pressure penetration are carried out through drag reduction and correction until all indicators meet the design requirements.

[0018] The beneficial effects of this invention are as follows: 1. This invention establishes a three-dimensional digital geological model through advanced drilling, classifies and categorizes the resistance zones in the circumferential and longitudinal directions of the pile body, and adopts a combination of ultrasonic vibration and high-pressure gas-liquid pulse for drag reduction in different areas. No chemical lubricating slurry is used throughout the process, avoiding groundwater and soil pollution. At the same time, directional enhanced drag reduction is implemented in conjunction with attitude deviation, forming a drag reduction closed-loop control and dynamically adjusting drag reduction parameters. This reduces the penetration resistance in high-resistance areas, avoids excessive drag reduction disturbing the soil, and achieves the optimal balance between drag reduction efficiency and pile foundation bearing capacity, adapting to the drag reduction construction needs of various complex geological formations.

[0019] 2. This invention constructs a precise and non-destructive deviation correction system that coordinates drag reduction and correction depth. When a deviation warning occurs in the pile body, drag reduction is first strengthened in the opposite direction of the deviation to reduce soil reaction force, creating low-resistance construction conditions for deviation correction. Then, a graded deviation correction strategy is implemented according to the degree of deviation. The pile body posture and stress are monitored in real time throughout the correction process, and the correction load and drag reduction power are dynamically adjusted to strictly control the pile body stress within the design range, avoiding problems such as pile bending and breakage, thereby improving the correction accuracy and pile body structural safety.

[0020] 3. This invention covers the entire construction process from modeling and calibration to final borehole verification. It collects multi-physics field data on pile-soil interaction through a multi-dimensional sensing system, dynamically updates the stratum model, and identifies construction anomalies in advance. It continuously iterates and optimizes drag reduction and correction parameters based on deep learning self-learning algorithms, achieving dynamic adaptation of construction parameters to stratum conditions. At the same time, the entire process data is encrypted and uploaded to the cloud platform to form a digital archive of the entire life cycle of a single pile, enabling full traceability and verification of the construction process. In the final borehole verification stage, the sensing system can also predict the bearing capacity of a single pile, and make collaborative fine adjustments when it does not meet the standards, thereby improving the overall quality of pile foundation engineering and the level of construction standardization. Attached Figure Description

[0021] Figure 1 This is a flowchart of the intelligent drag reduction and attitude correction method for static pressure displacement pile construction according to the present invention. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. 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.

[0023] like Figure 1 As shown, this embodiment of the invention provides an intelligent drag reduction and attitude correction method for static pressure displacement pile construction. The functional units execute coordinated linkage timing control requirements: data acquisition and transmission from the sensing system take precedence over all control units, with a data feedback delay not exceeding 0.5 seconds; after the control terminal issues drag reduction / correction commands, the corresponding unit must complete the start / stop response within 1 second; the drag reduction unit and the correction unit cannot operate at full load simultaneously; when the correction unit starts, the corresponding area's drag reduction unit maintains a low-power operating state; the start / stop and parameter adjustment of all units are uniformly scheduled by the control terminal; when a single unit malfunctions, the linkage protection is immediately triggered, suspending the operation of related units and issuing a fault warning.

[0024] Once a sudden change in strata is identified during construction (such as a sudden thickening of hard interlayers, a shift in the depth of dense sand layers, or a change in soil mechanical parameters exceeding 30%), the static pressure pile driving rate is immediately reduced to 50% of the original rate. At the same time, the execution of the current drag reduction parameters is suspended. The control terminal adjusts the drag reduction level classification in a timely manner according to the physical and mechanical parameters of the strata with the change: areas where the resistance increases by more than 50% after the change are directly designated as priority drag reduction zones, and the ultrasonic vibration power and high-pressure gas-liquid pulse pressure in the corresponding areas are simultaneously increased to 80% of the rated value. If the change in strata causes an instantaneous deviation in the pile posture, directional reinforcement drag reduction is immediately initiated and static pressure penetration is suspended. After the posture stabilizes, pile driving continues at a low rate until the pile penetrates into a stable stratum.

[0025] The static pressure pile driving rate control standard is implemented in stages: the pile driving rate for soft soil foundations is 2-3 cm / min, which can be increased to 3-4 cm / min in the conventional drag reduction zone and to 4-5 cm / min in the priority drag reduction zone; the pile driving rate for foundations in resistance-sensitive layers such as interbedded soft and hard soil and dense sand is 1-2 cm / min, which is maintained at 1-2 cm / min in the conventional drag reduction zone and increased to 2-3 cm / min in the priority drag reduction zone; during the correction operation, the pile driving rate is reduced to 0.5-1 cm / min. After the correction is completed and the pressure is maintained and the test is qualified, the rate is gradually restored to the standard rate of the corresponding stratum. Pile driving at excessive speed without drag reduction measures is prohibited throughout the entire process.

[0026] The modeling and calibration stage is specifically as follows: By conducting advanced continuous drilling at the pile location axis, physical and mechanical parameters of various strata within the entire depth range of the pile body are obtained, including soil cohesion, internal friction angle, compression modulus, water content, and density. Combined with the overall geological survey data of the site, a three-dimensional digital stratum model dedicated to the pile location is established to accurately divide the resistance-sensitive strata such as soft and hard interlayers, weak interlayers, hard interlayers, and dense sand layers, and to predict high resistance areas and easily deviated strata during the pile driving process. The advanced continuous drilling of the pile axis adopts the geological core drilling technology. The drilling diameter is 91mm. Drilling holes are symmetrically arranged within 1.5m on both sides of the pile axis with a hole spacing of 2m. The drilling depth extends to 5m below the design elevation of the pile end. The drilling depth accuracy is controlled within 0.1m. The formation core recovery rate is not less than 90%. Formation physical and mechanical parameter samples are collected every 1m.

[0027] The precast pile body integrates a distributed fiber optic sensing unit, a circumferentially equidistant ultrasonic vibration drag reduction unit, a circumferentially equidistant high-pressure gas-liquid pulse drag reduction unit at the pile end, and a multi-directional servo hydraulic correction unit at the pile top. It completes indoor performance calibration and on-site joint debugging, establishes the mapping relationship between sensing parameters and the soil resistance around the pile and the pile body posture deviation, completes the initial zero calibration of the system, and realizes the intelligent integration of the pile body itself, rather than the temporary addition of external equipment.

[0028] Distributed fiber optic sensing units are deployed along the entire longitudinal length of the pile, with one unit installed every 90 mm circumferentially. They are pre-embedded and fixed inside the pile's reinforcing cage, with an IP68 protection rating. Ultrasonic vibration drag reduction units are deployed every 3 m along the longitudinal length of the pile, with one unit installed in each of the four quadrants circumferentially. They are embedded in pre-reserved grooves on the sidewalls of the pile and fixed with high-strength epoxy mortar. High-pressure gas-liquid pulse drag reduction units are evenly installed on the end plates at the pile ends, corresponding one-to-one with the circumferential orientation of the ultrasonic vibration drag reduction units, and are connected by flanges. The multi-directional servo hydraulic correction unit at the pile top is installed in a pre-embedded steel sleeve at the pile top and welded to the main reinforcing bars of the pile. The wiring and piping of each functional unit are pre-embedded in pre-reserved channels in the pile body, and the channels are sealed and waterproofed.

[0029] The specific items for the initial zero-calibration of the system include the stress acquisition zero point of the distributed optical fiber sensing unit, the power output zero point of the ultrasonic vibration drag reduction unit, the pressure output zero point of the high-pressure gas-liquid pulse drag reduction unit, and the load and displacement zero point of the servo hydraulic correction unit. The accuracy error of the zero-calibration of each unit is controlled within 0.05%. After the calibration is completed, three no-load test runs are performed to verify the calibration effectiveness.

[0030] The reserved channels in the pile body are designed according to the unit pipeline / line specifications. The inner diameter of the cable channel is not less than 50mm, and the inner diameter of the hydraulic pipeline channel is not less than 80mm. The channels are laid out in a straight line along the longitudinal direction of the pile body, and the radius of curvature at the turning point is not less than 300mm. At the installation positions of the ultrasonic vibration drag reduction unit, the high-pressure gas-liquid pulse drag reduction unit and the servo hydraulic correction unit, the pile body steel cage is locally reinforced, the spacing of the stirrups is increased to 50% of the original spacing, and additional reinforcing bars are welded to the unit fixing structure to ensure that the design bearing capacity of the pile body structure is not reduced after the unit is installed.

[0031] The specific details of the perception initiation phase are as follows: After the pile body is hoisted and positioned, the initial bidirectional leveling of the pile body is completed through the pile top servo correction unit to ensure that the initial verticality deviation is controlled within 0.1%. Then, the multi-dimensional sensing system built into the pile body is activated. Throughout the static pressure pile driving process, the system collects data in real time at a sampling frequency of no less than 10Hz, including the pile body's XY bidirectional verticality deviation, the full distribution of axial stress in the pile body, the circumferential side friction data of the pile body, the pile end resistance, and the distribution of soil extrusion stress around the pile. All collected data are transmitted to the edge computing control terminal in real time. After the initial leveling is completed, the verticality is re-measured from two orthogonal directions of the pile using a dual total station. The re-measured data is compared with the data collected by the built-in sensing system of the pile. The deviation difference must be controlled within 0.02%. The sensing system can only be started after the comparison is qualified. If the comparison is not qualified, the bidirectional leveling is repeated.

[0032] The distributed optical fiber sensing unit has a stress acquisition accuracy of 0.1 MPa, a verticality deviation acquisition accuracy of 0.01%, a side friction and pile end resistance acquisition accuracy of 0.2 kPa, and a soil extrusion stress distribution data acquisition accuracy of 0.1 kPa. The transmission delay of all sensing data is controlled within 0.5 s.

[0033] The terminal dynamically updates the actual parameters of the three-dimensional geological model by combining the collected data, and identifies geological abrupt changes and abnormal trends in pile posture in advance, realizing the transformation from post-discovery to pre-prediction.

[0034] The specific details of the resistance grading stage are as follows: Based on real-time collected data on the circumferential and longitudinal resistance of the pile, and combined with a dynamically updated geological model, the control terminal divides the pile into four quadrants along the circumference and into multiple control segments along the longitudinal direction according to the geological strata. It accurately identifies the areas with excessive side friction and soil extrusion stress in each zone and each control segment, calculates the drag reduction requirements for different areas, and classifies them into three categories: priority drag reduction area, conventional drag reduction area, and no drag reduction area. Vertical stratigraphic segmentation is based on a 2m thickness threshold. If the lithology of the stratigraphy changes abruptly, even if the thickness is less than 2m, it is still classified as a separate control segment. The criterion for exceeding the standard for side friction resistance is that it is greater than 1.2 times the design side friction resistance of the corresponding stratum. The criterion for exceeding the standard for soil compressive stress is that it is greater than 0.8 times the ultimate compressive strength of the corresponding stratum soil. The priority drag reduction zone is the area where the side friction resistance exceeds the standard by 1.5 times or more, or the soil compressive stress exceeds the standard by 1.2 times or more. The conventional drag reduction zone is the area where the side friction resistance exceeds the standard by 1.2-1.5 times or the soil compressive stress exceeds the standard by 0.8-1.2 times. The non-drag reduction zone is the area that does not meet the criteria for exceeding the standard.

[0035] By using the spatial distribution data of resistance, we can determine whether the uneven circumferential resistance around the pile is the core cause of the pile's attitude deviation. We can establish a coupled correlation model between abnormal resistance distribution and the trend of pile attitude deviation, clarify the directional resistance reduction requirements needed to eliminate attitude deviation, realize the linkage analysis between resistance reduction requirements and correction requirements, and locate the core cause of pile deviation.

[0036] The drag reduction control stage is specifically as follows: The control terminal issues control commands to the drag reduction units in the corresponding areas according to the drag reduction requirements of the zones and the directional drag reduction requirements, and executes differentiated drag reduction control: For priority drag reduction zones, the ultrasonic vibration drag reduction unit of the pile body and the high-pressure gas-liquid pulse drag reduction unit at the corresponding position of the pile tip are activated simultaneously. The ultrasonic vibration causes instantaneous liquefaction of the soil around the pile, which greatly reduces the side friction of the pile body. The high-pressure gas-liquid pulse at the pile tip forms a local air curtain buffer layer, which reduces the penetration resistance of the pile tip; For conventional drag reduction zones, only the low-power ultrasonic vibration drag reduction unit is activated to maintain a low resistance state; For areas without drag reduction, no drag reduction unit is activated. The basic vibration frequency of the ultrasonic vibration drag reduction unit is 20-50kHz, the low-power operating range is 500-1000W, the ultrasonic vibration power in the priority drag reduction zone is 1500-3000W, and the basic power in the corresponding area is increased by 80%-100% when drag reduction is strengthened; the medium of the high-pressure gas-liquid pulse is a mixture of clean water and compressed air, the gas-liquid volume ratio is 1:2, the pulse frequency is 5-10Hz, the basic output pressure is 1.5-3MPa, the pulse pressure in the priority drag reduction zone is increased to 3-5MPa, and the basic pressure in the corresponding area is increased by 60%-80% when drag reduction is strengthened; the effective range of the ultrasonic vibration causing instantaneous liquefaction of the soil around the pile is 0.3-0.5m outside the pile body, and the effective range of the air curtain buffer layer formed by the high-pressure gas-liquid pulse is 0.2-0.4m outside the pile tip.

[0037] In response to the trend of pile posture deviation, enhanced drag reduction control is implemented in the area in the opposite direction of the deviation to reduce the stiffness and reaction force of the soil in the area in advance, creating low-resistance soil conditions for subsequent posture correction operations, and achieving pre-emptive synergy between drag reduction and correction. Directional reinforcement and drag reduction are initiated in advance when the pile attitude deviation trend appears but has not reached the warning threshold. When the deviation reaches the warning threshold, drag reduction is continuously reinforced until the soil resistance drops to the safe threshold. The safe threshold for soil resistance is determined to be below 60% of the original side friction of the corresponding stratum, and the compressive stress of the soil around the pile drops to below 40% of the ultimate compressive strength of the corresponding stratum. After the resistance data is stable within the safe threshold range for 3 consecutive seconds, it is determined to meet the low resistance soil conditions for correction.

[0038] During the drag reduction process, the sensing system collects drag change data in real time and dynamically adjusts the power and duration of the drag reduction unit to form a drag reduction closed-loop control. This achieves efficient drag reduction while avoiding large-scale disturbance of the soil around the pile and loss of pile bearing capacity caused by excessive drag reduction, and no chemical lubricating grout is used throughout the process.

[0039] The criteria for stopping the drag reduction unit are as follows: If the resistance in the priority drag reduction zone drops to the threshold of the conventional drag reduction zone and remains stable for 5 consecutive seconds, or if the resistance in the conventional drag reduction zone drops to the threshold of the non-drag reduction zone and remains stable for 5 consecutive seconds, or if the pile penetrates to the design elevation of that section, the corresponding drag reduction unit should be stopped immediately. Once the pile attitude deviation is eliminated, the drag reduction unit for directional reinforcement drag reduction should be stopped immediately. Monitoring of soil disturbance around the pile is based on the rate of change of soil compressive stress. If the single rate of change of soil compressive stress exceeds 20% or the cumulative rate exceeds 30%, the soil disturbance is considered to be close to exceeding the standard, and the power of the drag reduction unit should be immediately reduced. If the rate of change of soil compressive stress exceeds 40%, the soil disturbance is considered excessive, and the corresponding drag reduction unit should be stopped immediately. After allowing the soil to stand for 3-5 minutes, the measurement should be repeated, and the parameters should be adjusted and restarted once the stress has returned to a stable state.

[0040] The attitude correction stage is specifically as follows: When the real-time monitored verticality deviation of the pile reaches the preset warning threshold, the control terminal first performs the reverse direction reinforcement drag reduction operation in the drag reduction control stage. After the soil resistance in the corresponding area drops to the preset safety threshold, the multi-directional servo hydraulic correction unit at the top of the pile is activated. According to the direction of the pile deviation, the amount of deviation, and the stratum conditions, graded correction control is performed: For slight deviation (0.3%), a low-load uniform speed correction mode is adopted, and a stable correction reaction force is continuously applied until the deviation returns to the allowable range; for medium deviation (0.3% to 0.5%), a graded progressive correction mode is adopted, and the correction load is gradually increased. After each load is maintained, the pile posture is re-measured to gradually correct the deviation; for larger deviation (0.5% to 1.0%), a cyclic correction mode of drag reduction, correction, pressure maintenance, and re-measurement is adopted. After each correction, the pressure is maintained to stabilize, and then re-measurement and adjustment are performed to avoid pile bending caused by a single large load correction. The warning threshold for pile verticality deviation is set at 0.2%. Once this threshold is reached, reverse direction reinforcement and drag reduction operations are immediately triggered. The load value of the low-load uniform speed correction mode is 10%-15% of the pile's design compressive strength, and the correction rate is 0.01% / s. The graded progressive correction mode increases the load by 5% of the pile's design compressive strength each time, and the pressure holding time for each load level is 5 minutes. After pressure holding, the pile posture is re-measured to determine whether to continue increasing the load. The cyclic correction mode controls the single verticality correction amount to within 0.05%, holds the pressure for 10 minutes after each correction, and the cycle interval is 2 minutes until the deviation drops below the warning threshold.

[0041] Throughout the correction process, the sensing system collects pile posture and stress data in real time, dynamically adjusts the magnitude, loading rate and drag reduction power of the correction load, forming a closed-loop control that coordinates drag reduction and correction. The pile stress is kept within the design allowable range throughout the process until the pile verticality returns to the standard and design allowable deviation range, achieving non-destructive and precise correction.

[0042] The core monitoring points for pile stress are set at the pile top, half the depth of the pile, 3m above the pile tip, and at the interface between the soft and hard strata. Each monitoring point is equipped with stress sensing points in four quadrants around the circumference. The allowable range of pile stress design is capped at 70% of the standard value of the axial compressive strength of the precast pile concrete, and shall not exceed 60% of the design value of the tensile strength of the pile reinforcement. The stress data at any monitoring point shall not exceed the above range.

[0043] The optimized traceability stage is specifically as follows: Throughout the entire pile driving process, the edge computing control terminal, based on real-time collected stratum parameters, resistance data, attitude data, and pile stress data, continuously iterates and optimizes the starting power, duration, and zonal combination strategy of the drag reduction unit, as well as the load level, loading rate, and correction cycle parameters of the correction unit, through the built-in deep learning self-learning optimization algorithm. Under the premise of ensuring pile driving efficiency, it achieves the optimal balance between drag reduction efficiency and pile bearing capacity, and the optimal balance between correction accuracy and pile structural safety. The deep learning self-learning optimization algorithm is built on the BP neural network framework. It takes formation parameters, resistance data, attitude data, and pile stress data as input layers and core control parameters for resistance reduction and deviation correction as output layers. Three hidden layers are set. After each construction, the entire process data is included in the sample library for model training and iteration. The construction data is uploaded to the cloud platform and encrypted using the national cryptographic SM4 symmetric encryption algorithm. Data transmission adopts the HTTPS protocol, and the cloud platform data storage adopts an off-site disaster recovery backup mode with a backup interval of 1 hour.

[0044] The communication between the cloud platform and the control terminal adopts a dual-link mode of industrial-grade wireless communication + wired backup. The wireless communication bandwidth is no less than 10Mbps and the wired communication bandwidth is no less than 100Mbps to ensure real-time data transmission. The communication disconnection judgment standard is that the data transmission interruption exceeds 3 seconds. After the disconnection, the reconnection mechanism is triggered immediately, and the control terminal automatically switches to the backup communication link. At the same time, the construction data is cached locally. The cache capacity can store no less than 2 hours of full construction data. After the communication is restored, the locally cached data is automatically retransmitted to the cloud platform. After the retransmission is completed, the data integrity is verified to ensure that there are no missing or incorrect data.

[0045] All geological data, sensing and monitoring data, drag reduction control parameters, deviation correction control parameters, and equipment operating parameters throughout the entire construction process are simultaneously encrypted and uploaded to the cloud management platform to form a digital archive of the entire life cycle of single pile construction, enabling full traceability and verification for each pile.

[0046] The digital archives for the entire lifecycle of a single pile are categorized and stored in six major categories: geological survey data, construction monitoring data, equipment operation data, drag reduction and correction control data, final borehole verification data, and bearing capacity prediction data. The archives are permanently stored. The cloud platform has three levels of access permissions: Level 1 is for administrators, who can perform all data operations; Level 2 is for construction units, who can query and modify the construction data for this project; and Level 3 is for supervision and acceptance units, who can only query the archive data. All data operations are logged and the operator, operation time, and operation content are recorded.

[0047] The final hole verification stage is specifically as follows: After the pile is driven to the design elevation by static pressure, the static pressure penetration operation is stopped. The final hole multi-parameter verification is completed through the sensing system built into the pile: the final verticality of the pile in both X and Y directions, the stress distribution of the entire pile section, the rebound stress of the soil around the pile, and the depth of the pile tip embedded in the stable stratum are measured simultaneously. Combined with the monitoring data of the entire construction process and the stratum model, the vertical ultimate bearing capacity of a single pile is predicted through the built-in bearing capacity prediction model. The core inputs to the single-pile vertical ultimate bearing capacity prediction model are the pile tip embedment depth in stable strata, the average side friction resistance of the entire pile body, the peak value of the pile tip resistance, the rebound stress of the soil around the pile, and the compressibility modulus of the strata. The core outputs are the single-pile vertical ultimate bearing capacity and the bearing capacity safety factor. The reusable core unit inside the pile body adopts a modular plug-and-play recovery method, which is hydraulically disassembled through a reserved interface at the pile top. The recovered components include a distributed optical fiber sensing unit, an ultrasonic vibration drag reduction unit, a high-pressure gas-liquid pulse drag reduction unit, and a servo hydraulic correction unit. The reset calibration items after recovery include full parameter calibration of power, pressure, load, displacement, and acquisition accuracy. The error of each parameter after calibration must be controlled within 0.05%. After calibration, a sealing test and no-load test run are performed. Only after passing the test can it be used again.

[0048] The reusable core units within the pile body have a set cumulative service life. The cumulative service time of the distributed optical fiber sensing unit shall not exceed 500 hours, the cumulative service time of the ultrasonic vibration drag reduction unit shall not exceed 300 hours, the cumulative service time of the high-pressure gas-liquid pulse drag reduction unit shall not exceed 200 hours, and the cumulative service time of the servo hydraulic correction unit shall not exceed 400 hours. The criteria for on-site replacement are: the accuracy error of the unit after calibration exceeds 0.05%, leakage occurs during sealing detection, the start-stop response delay exceeds 1 second during no-load test run, and abnormal noise or parameter fluctuation occurs during operation. Any of these situations shall be deemed as requiring on-site replacement. After replacement, the new unit must complete the full-process calibration before it can be put into use.

[0049] After confirming that all indicators meet the design and specification requirements, shut down all sensing, drag reduction, and correction units, complete the recovery and resetting calibration of the reusable core unit inside the pile body, and prepare for the cyclic construction of the next pile. If the final borehole verification reveals that the indicators do not meet the standards, a final fine-tuning and correction system is used to supplement static pressure penetration until all indicators meet the design requirements and the single pile construction is completed.

[0050] The penetration force of static pressure penetration shall not exceed 80% of the rated static pressure of the pile driver and shall not exceed 90% of the design compressive bearing capacity of the pile body. The single supplementary penetration depth shall be controlled within 5cm, and the maximum supplementary penetration of a single pile shall not exceed 50cm. After each penetration, the pile body posture and bearing capacity shall be re-measured after 3 minutes of static rest. The qualification criteria for the prediction of the vertical ultimate bearing capacity of a single pile are that the predicted value is not less than 1.1 times the design requirement of the vertical ultimate bearing capacity of the single pile, and the bearing capacity safety factor is not less than 2.0. At the same time, the depth of the pile tip embedded in the stable stratum meets the design requirements. Only when all three criteria are met can the bearing capacity prediction be deemed qualified.

[0051] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "include," "contain," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0052] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An intelligent drag reduction and attitude correction method for static pressure displacement pile construction, characterized in that, include: Modeling and calibration stage: Before construction, the stratum parameters of the pile body at full depth are obtained by continuous drilling ahead of the pile axis. A three-dimensional digital stratum model is established in combination with the site geological data, the resistance-sensitive layer is divided and the high resistance and easy deviation areas are predicted. Functional units are integrated into the precast pile body, the performance is calibrated and integrated, and the mapping relationship between the sensing parameters and the pile perimeter resistance and pile body attitude deviation is established. Sensing and initiation phase: The multi-dimensional sensing system built into the pile body is activated, and relevant data is collected at high frequency and transmitted to the control terminal throughout the pile driving process. The terminal combines the data to dynamically update the stratum model and identify stratum changes and pile body posture abnormalities in advance. Resistance grading stage: The control terminal combines real-time resistance data with dynamic geological models to divide the pile body into circumferential and longitudinal sections, identify areas with excessive resistance and classify resistance reduction levels, correlate abnormal resistance distribution with pile body attitude deviation, and clarify directional resistance reduction requirements. Drag reduction control stage: The control terminal issues instructions to the corresponding functional units to execute differentiated drag reduction operations according to the zoning and directional drag reduction requirements, strengthens drag reduction in the area opposite to the pile body attitude deviation, and collects resistance data in real time and dynamically adjusts parameters. Attitude correction stage: When the verticality deviation of the pile reaches the warning threshold, the control terminal first performs the reverse direction reinforcement and drag reduction. After the soil resistance drops to a safe range, the correction unit is started and graded correction is performed according to the deviation. The parameters are monitored and dynamically adjusted in real time throughout the process. Optimization and traceability phase: Throughout the entire pile driving process, the control terminal iteratively optimizes the drag reduction and correction parameters through a self-learning algorithm; at the same time, all construction process parameters are uploaded to the cloud platform to form a digital archive of the entire life cycle of a single pile; Final drilling verification stage: After the pile body sinks to the design elevation, the drilling stops. The multi-parameter final drilling verification is completed through the sensing system and the bearing capacity of a single pile is predicted. If the indicators meet the standards, the unit is closed and reusable components are retrieved; if the standards do not meet the standards, fine-tuning and correction and supplementary drilling are carried out until the requirements are met.

2. The intelligent drag reduction and attitude correction method for static pressure displacement pile construction according to claim 1, characterized in that, In the modeling and calibration stage, the geological parameters include soil cohesion, internal friction angle, compression modulus, water content, and density; the resistance-sensitive layers include interbedded soft and hard layers, weak interlayers, hard interlayers, and dense sand layers; the functional units include a distributed optical fiber sensing unit, a circumferential zoned ultrasonic vibration drag reduction unit, a pile end zoned high-pressure gas-liquid pulse drag reduction unit, and a pile top multi-directional servo hydraulic correction unit; and the performance calibration and joint debugging include indoor calibration, on-site joint debugging, and initial zeroing calibration of the system.

3. The intelligent drag reduction and attitude correction method for static pressure displacement pile construction according to claim 2, characterized in that, During the sensing activation phase, after the pile body is hoisted into place, the initial bidirectional leveling is completed by the pile top servo correction unit to ensure that the initial verticality deviation is controlled within the preset range. The acquisition frequency of the sensing system is not lower than the preset value, and the acquired data includes the bidirectional verticality deviation of the pile body, the axial stress distribution of the pile body, the zoning data of the pile periphery side friction, the pile end resistance, and the distribution data of the soil extrusion stress around the pile.

4. The intelligent drag reduction and attitude correction method for static pressure displacement pile construction according to claim 3, characterized in that, In the resistance grading stage, the pile body is divided into zones according to a preset number of circumferences and into layers according to the soil strata in the longitudinal direction; the resistance reduction level is divided into three categories: priority resistance reduction zone, conventional resistance reduction zone, and no resistance reduction zone; a coupled correlation model between resistance distribution anomalies and pile body posture deviation trends is established through resistance spatial distribution data to realize the linkage analysis of resistance reduction and correction requirements.

5. The intelligent drag reduction and attitude correction method for static pressure displacement pile construction according to claim 4, characterized in that, During the drag reduction control phase, the ultrasonic vibration drag reduction unit and the high-pressure gas-liquid pulse drag reduction unit at the corresponding azimuth of the pile end are activated simultaneously in the priority drag reduction zone. Only the low-power ultrasonic vibration drag reduction unit is activated in the conventional drag reduction zone, and no drag reduction unit is activated in the non-drag reduction zone. The core of enhanced drag reduction is to reduce the stiffness and reaction force of the soil in the opposite direction of the deviation in advance.

6. The intelligent drag reduction and attitude correction method for static pressure displacement pile construction according to claim 5, characterized in that, During the attitude correction stage, the graded correction is divided into three categories according to the degree of deviation: slight deviation, moderate deviation, and large deviation, and corresponding correction modes are adopted for each category. Throughout the correction process, the stress of the pile body is always controlled within the design allowable range until the verticality returns to the standard and the design allowable deviation.

7. The intelligent drag reduction and attitude correction method for static pressure displacement pile construction according to claim 6, characterized in that, During the optimization and tracing phase, the self-learning algorithm iteratively optimizes the starting power, duration of action, and zonal combination strategy of the drag reduction unit and the load level, loading rate, and correction cycle parameters of the correction unit based on real-time collected data on strata, resistance, attitude, and pile stress. The data uploaded to the cloud platform includes strata data, sensing and monitoring data, control parameters, and equipment operating parameters.

8. The intelligent drag reduction and attitude correction method for static pressure displacement pile construction according to claim 7, characterized in that, In the final hole verification stage, multi-parameter verification includes re-measuring the final verticality of the pile in both directions, the stress distribution of the entire pile section, the rebound stress of the soil around the pile, and the depth of the pile tip embedded in stable strata; bearing capacity prediction is achieved by combining the built-in bearing capacity prediction model with data from the entire construction process; reusable components need to be reset and calibrated after recycling.

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