A method for demolishing steel pipe piles combining helical disturbance and vibration extraction

Abstract

This invention discloses a method for dismantling steel pipe piles by combining spiral disturbance and vibration extraction. This invention relates to the field of pile foundation engineering construction technology. It utilizes a synchronized spiral disturbance and vibration extraction operation throughout the entire process, coupled with tiered emergency response, to achieve low-resistance, low-disturbance, and stable dismantling of steel pipe piles. The advantages of this invention are: by constructing a synchronized spiral disturbance and vibration extraction operation mechanism, it breaks through the industry's entrenched technical bias of completing the drag reduction process first and then implementing the pile extraction operation. Throughout the entire steel pipe pile extraction process, the spiral disturbance device remains in situ, and with precise timing control of the pile extraction and disturbance processes, it solves the inherent defects of existing step-by-step processes, such as rapid collapse and shrinkage of the soil around the pile after the drag reduction operation stops, re-bonding of the pile-soil interface, and rapid increase in pile side friction resistance. This achieves a continuous low-friction state throughout the entire pile extraction process.

Description

Technical Field

[0001] This invention relates to the field of pile foundation construction technology, specifically to a method for dismantling steel pipe piles that combines helical disturbance and vibration extraction. Background Technology

[0002] Pile foundation engineering is a core branch of civil engineering and geotechnical engineering, and a crucial link in ensuring load transfer and structural stability for various buildings and infrastructure projects. Steel pipe piles, as a high-performance pile foundation type, are widely used in various engineering scenarios such as ports and wharves, bridges across rivers and seas, temporary support for deep foundation pits, urban rail transit, reinforcement and renovation of existing buildings, coastal protection projects, and temporary support for large steel structures, thanks to their core advantages such as high vertical bearing capacity, outstanding bending and shear resistance, strong adaptability to different geological formations, fast construction speed, recyclability, and environmental friendliness. They are an indispensable and important engineering component in my country's infrastructure construction and urban renewal process. Existing steel pipe pile demolition technologies mainly rely on vibratory hammers for direct, forceful extraction, followed by pre-drag reduction treatment around the pile and subsequent hoisting for removal. This approach has several drawbacks. First, existing processes often employ a fragmented construction logic of drag reduction followed by pile extraction. After drag reduction ceases, the surrounding soil is prone to collapse and shrinkage, leading to a rapid increase in pile-side friction due to re-bonding at the pile-soil interface. This makes the drag reduction effect unsustainable, resulting in frequent pile jamming, breakage, and equipment overload accidents. Demolition of large-diameter, deep-embedded steel pipe piles is extremely difficult. Second, existing technologies cannot simultaneously achieve significant reduction in extraction resistance and precise control of construction disturbance. Conventional solutions are merely simple combinations of known processes without synergistic mechanisms. Vibration energy and soil disturbance tend to diffuse indiscriminately into the far field, making them unsuitable for the stringent construction requirements of sensitive conditions such as densely populated urban areas and existing railway line upgrades. Therefore, we propose a steel pipe pile demolition method combining helical disturbance and vibratory extraction. Summary of the Invention

[0003] The purpose of this invention is to provide a method for demolishing steel pipe piles that combines helical disturbance and vibration extraction.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a method for dismantling steel pipe piles combining helical disturbance and vibration extraction, the method comprising the following steps: Step 1: Complete the pre-construction survey and standardized pre-treatment of the pile perimeter, identify the distribution of underground obstacles around the pile, delineate the safe working area and spiral disturbance boundary, and simultaneously complete the pile top cleaning, annular diversion trench excavation and high-pressure pre-washing of the pile-soil interface. Step 2: Coaxially install the hollow spiral drill rod with high-pressure water injection system on the outside of the steel pipe pile to be demolished, and complete the installation and multi-system linkage debugging of the spiral disturbance system and the pile top hydraulic vibration extraction system. Step 3: Drive the auger drill rod to rotate counterclockwise along the outer wall of the steel pipe pile and drill downwards. During the drilling process, high-pressure water is injected into the pile-soil interface to form a continuous annular disturbance and drag reduction zone and a closed-loop lubricating mud sleeve around the pile. Step 4: After drilling to the designed pile bottom elevation, maintain pressure and stabilize the drill to complete the targeted softening of the soil at the pile tip and the drag reduction and strengthening of the entire pile length. Keep the auger rod rotating in place and the high-pressure water injection state uninterrupted throughout the process. Step 5: While maintaining in-situ disturbance of the auger drill rod and high-pressure water injection, start the vibratory hammer to apply high-frequency low-amplitude vibration, and adopt a segmented uniform speed extraction method. Through the coordinated operation of disturbance and extraction, the steel pipe pile is extracted smoothly with low resistance. Step 6: Monitor the pile extraction status in real time during the operation, and execute the graded emergency response procedure when a pile jamming failure is triggered; Step 7: After completing the integrity acceptance of the extracted pile, dismantle and remove the equipment and backfill and compact the pile hole in layers.

[0005] As a further aspect of the present invention: Step one specifically involves: First, using ground-penetrating radar combined with manual pit exploration, the distribution, burial depth, and planar location of underground pipelines, existing structural foundations, and underground obstacles within a 3m radius around the steel pipe pile to be demolished are identified. Based on the survey results, a ring-shaped safe working area and a spiral disturbance working boundary are delineated centered on the axis of the steel pipe pile. Simultaneously, the work site is leveled and the bearing capacity is reinforced. Subsequently, debris, rust, and deformed parts of the auxiliary structures such as the top flange and stiffening ribs of the steel pipe pile are removed. Within the delineated spiral disturbance working boundary, a ring-shaped shallow diversion ditch is excavated around the steel pipe pile. The depth of the diversion ditch is controlled at 100mm-200mm, and the width is controlled at 150mm-300mm. Finally, a high-pressure water gun with a fan-shaped nozzle is used to perform circumferential pre-rinsing along the interface between the steel pipe pile and the soil. The high-pressure water pressure is precisely controlled at 10MPa-20MPa, and the nozzle spray direction is obliquely downward, pointing towards the interface between the pile and the soil. The entire cross-section is pre-rinsed by moving at a uniform speed around the pile.

[0006] As a further aspect of the present invention: In step two, specifically: a hollow spiral drill rod with a high-pressure water injection system is coaxially sleeved on the outside of the steel pipe pile to be demolished. The inner diameter of the spiral drill rod is 20mm-50mm larger than the outer diameter of the steel pipe pile to be demolished. Guide rollers, evenly distributed circumferentially along the outer wall of the steel pipe pile, are installed on the inner wall of the guide cone at the lower end of the spiral drill rod. The gap between the guide rollers and the outer wall of the steel pipe pile is controlled at 2mm-5mm to ensure that the coaxiality deviation between the spiral drill rod and the steel pipe pile does not exceed 3‰ during drilling. Then, the upper end of the spiral drill rod is connected via a flange. The hydraulic power head is rigidly connected to the output shaft of the hydraulic drive head. The hydraulic power head is fixedly installed on a liftable guide bracket with a vertical slide rail. The verticality deviation of the guide bracket does not exceed 2‰. Simultaneously, the hydraulic vibratory hammer is installed on the top of the steel pipe pile through a special hydraulic wedge clamp. The inner wall of the clamp claw is embedded with anti-slip tooth plates. The clamping force is set to be no less than 1.5 times the self-weight of the steel pipe pile. Finally, the linkage debugging of the spiral disturbance system, vibration extraction system, high-pressure water injection system and real-time monitoring system is completed, and the action sequence, parameter feedback and emergency trigger logic of each system are calibrated.

[0007] As a further aspect of the present invention: Step three specifically involves: after completing system debugging, starting the hydraulic drive power head to drive the hollow spiral drill rod to drill vertically downwards along the outer wall of the steel pipe pile in a counter-rotating manner. The counter-rotating direction matches the soil conveying direction of the spiral blades on the outer wall of the spiral drill rod, so that the spiral blades continuously transport the cut soil upwards along the spiral channel to the surface diversion ditch during the rotation process. During the drilling process, the drilling speed is dynamically adjusted according to the engineering characteristics of the soil layers around the pile. In the soft plastic-fluid plastic clay layer, the drilling speed is controlled at 0.5m / min-1.0m / min, and in the hard plastic clay layer, medium dense and dense sand... The drilling speed is reduced to 0.2m / min-0.5m / min during the drilling process. Simultaneously, a high-pressure water injection system is activated, continuously injecting high-pressure water into the soil-pile interface through high-pressure water injection nozzles spaced longitudinally along the inner wall of the auger drill rod. The water injection pressure is dynamically controlled between 15MPa and 30MPa based on soil permeability and pile perimeter constraints. The water injection flow rate is set at 10L / min-30L / min per meter of pile length. This forms a continuous, uniform annular disturbance and drag reduction zone and a closed-loop lubricating mud sleeve around the steel pipe pile. The outer diameter of the annular disturbance and drag reduction zone is 150mm-300mm larger than the outer diameter of the steel pipe pile. Throughout the drilling process, the output torque of the hydraulic power head, the vertical feed force, and the pressure and flow parameters of the high-pressure water injection system are monitored in real time. When the output torque exceeds 80% of the set threshold, the drilling speed is automatically reduced and the water injection pressure is increased.

[0008] As a further aspect of the present invention: In step four, specifically: after the hollow auger drill rod is reverse-drilled to the designed pile bottom elevation of the steel pipe pile, the vertical feed of the drill rod is stopped, and the reverse rotation of the auger drill rod is maintained at the designed depth position for pressure holding and stabilizing drilling operations. The stabilizing drilling rotation speed is consistent with the rotation speed during the drilling process, and the stabilizing drilling time is controlled between 1 minute and 3 minutes. During the stabilizing drilling process, the working state of the high-pressure water injection system is continuously maintained, and the water injection pressure is stabilized at the upper limit value during the drilling process, so that the high-pressure water continuously diffuses along the pile-soil interface to the bottom of the steel pipe pile end, fully softening the soil of the bearing layer at the pile end. At the same time, through the continuous rotation of the auger drill rod, the annular disturbance and drag reduction zone around the entire pile length is subjected to secondary cutting disturbance, and high-pressure water and mud medium are replenished to repair the closed-loop lubricating mud sleeve. After completing the stabilizing drilling and drag reduction strengthening operations, the in-situ rotation of the auger drill rod and the high-pressure water injection state are maintained without interruption.

[0009] As a further aspect of the present invention: Step five specifically involves: while the hollow spiral drill rod remains in place and continues to rotate in reverse with high-pressure water injection, a hydraulic vibratory hammer is activated to perform a coordinated extraction operation. The vibratory hammer applies high-frequency, low-amplitude vertical vibration to the steel pipe pile, with the vibration frequency precisely controlled between 20Hz and 40Hz and the amplitude controlled between 2mm and 8mm. The maximum excitation force of the vibratory hammer is set according to the theoretical ultimate extraction resistance of the steel pipe pile, and the maximum excitation force is taken as 1.5 times to 2.0 times the theoretical ultimate extraction resistance, wherein the theoretical ultimate extraction resistance is calculated by the following formula: ; in, This represents the theoretical ultimate pull-out resistance of the steel pipe pile, expressed in kN. The ultimate side friction resistance per unit area of ​​each soil layer around the pile, expressed in kPa. This refers to the total surface area of ​​the steel pipe pile side, in m². 2 , This represents the ultimate bearing capacity per unit area of ​​the pile tip bearing layer, expressed in kPa. This refers to the annular bearing area at the pile tip of the steel pipe pile, expressed in m². 2 The vibratory extraction adopts a segmented, uniform-speed extraction method. The single extraction length of each segment is controlled between 0.5m and 1.0m. After each segment is extracted, the vibration and extraction actions are paused to check and calibrate the verticality of the steel pipe pile and the installation status of the clamp. Throughout the extraction process, the auger and vibratory hammer maintain a strict coordinated working sequence. When the vibratory hammer starts vibrating and vertically extracting, the auger maintains low-speed reverse rotation and constant high-pressure water injection. During the interval when the vibratory hammer pauses extraction for attitude calibration, the auger appropriately increases the rotation speed and water injection pressure. Through a closed-loop operation mode of simultaneous disturbance and extraction, the steel pipe pile is smoothly extracted until the entire steel pipe pile is completely detached from the pile hole.

[0010] As a further aspect of the present invention: In step six, during the extraction operation, real-time data of pile extraction resistance, vibratory hammer excitation force load rate, and pile extraction speed are continuously collected by a real-time monitoring system. When any one of the following three conditions is detected—pile extraction resistance exceeding the set limit threshold, vibratory hammer excitation force load rate continuously exceeding 90%, or pile body without effective extraction displacement for 5 consecutive seconds—the system automatically determines it as a pile jamming fault and triggers a graded emergency response process. First, implement Level 1 emergency response: immediately suspend the vibration and extraction operations of the vibratory hammer, maintain the in-situ rotation of the auger drill rod and the high-pressure water injection without interruption, activate the reciprocating bidirectional rotation function of the auger drill rod, and control the hydraulic power head to alternately rotate forward and backward. The duration of each forward and reverse rotation should be controlled within 10-30 seconds, and the rotation speed should be consistent with the drilling process. Increase the outer diameter of the disturbed area by 100-200 mm. Simultaneously, increase the water injection pressure of the high-pressure water injection system to 30-40 MPa and the water injection flow rate to 1.5-2.0 times the original set value. Use pulsed water injection to impact the pile-soil interface. If the pile extraction resistance still does not drop below the set threshold after the Level 1 emergency response is completed, [further action will be taken]. If the situation escalates to Level II emergency response, based on Level I response, add either bentonite or polymer mud to the water in the high-pressure water injection system. The viscosity of the prepared mud should be controlled between 30s and 60s. Simultaneously extend the stabilization time of the bidirectional reciprocating rotation to 3-5 minutes. After completing the response, restart the vibration extraction operation. If effective extraction cannot be achieved after two or more Level II emergency responses, execute Level III emergency response. First, pull the entire auger rod upward at a uniform speed out of the steel pipe pile working area. Then, use either a percussion cone or a soil sampling drill to extract soil from the core of the entire pile inside the steel pipe pile. After the core soil extraction is completed, reinstall the auger disturbance device and repeat the disturbance, drag reduction, and coordinated extraction operations until the steel pipe pile is completely extracted.

[0011] As a further aspect of the present invention: In step seven, after the steel pipe pile is completely pulled out, the integrity of the pulled-out steel pipe pile is first checked to confirm that there are no broken sections or residual segments left in the pile hole. Simultaneously, the mud cleaning, debris removal, and site leveling of the work surface are completed. Then, the spiral disturbance device, hydraulic vibratory hammer, and supporting auxiliary equipment are disassembled in sequence. After the equipment is inspected and maintained, they are orderly removed from the site. Finally, the pile hole formed after the steel pipe pile is pulled out is backfilled in a standardized manner. According to the site usage requirements and geological conditions around the pile hole, graded sand and gravel and cement-soil mixture are used for layered backfilling and compaction. The thickness of each backfill layer is controlled at 200mm-300mm, and the layer compaction coefficient is not less than 0.93. After the backfilling is completed, the surface at the top of the pile hole is leveled and hardened to complete the entire process of steel pipe pile demolition.

[0012] Compared with the prior art, the beneficial effects of the present invention by adopting the above technical solution are as follows: 1. This invention breaks through the industry's fixed technical bias of completing the drag reduction process first and then carrying out the pile extraction operation by constructing a synchronized spiral disturbance and vibration extraction operation mechanism. It maintains the spiral disturbance device in situ throughout the entire steel pipe pile extraction process. Combined with the precise timing and coordinated control of the pile extraction and disturbance processes, it solves the inherent defects of the existing step-by-step process, such as the rapid collapse and shrinkage of the soil around the pile after the drag reduction operation stops, the re-bonding of the pile-soil interface, and the rapid increase of the pile side friction after the drag reduction operation stops. It achieves a continuous low friction state throughout the entire pile extraction process, significantly reduces the peak value of the pile extraction resistance, effectively avoids pile jamming, pile breakage and equipment overload accidents, and reduces the performance requirements of large-diameter and deep-penetrated steel pipe pile demolition operations. 2. This invention solves the long-standing contradiction in existing steel pipe pile demolition technologies by constructing a dual disturbance control system that matches coaxial directional ring disturbance with high-frequency low-amplitude vibration, and a closed-loop synergistic effect mechanism that integrates helical mechanical cutting, high-pressure water jet lubrication, and high-frequency vibration breaking adhesion. This is achieved by constructing a dual disturbance control system that matches coaxial directional ring disturbance with high-frequency low-amplitude vibration, and a closed-loop synergistic effect mechanism that integrates helical mechanical cutting, high-pressure water jet lubrication, and high-frequency vibration breaking adhesion. It also avoids the problem that conventional technical solutions are simply splicing together known processes without synergistic effect, achieving directional and precise disturbance of the soil around the pile, avoiding indiscriminate far-field diffusion of vibration energy and high-pressure water jet, significantly reducing the disturbance impact of construction on surrounding existing buildings, underground pipelines, and foundations, and achieving a significant reduction in pile extraction resistance. It can be adapted to working conditions with stringent requirements for construction disturbance control, such as densely populated urban areas and existing line reconstruction, and greatly expands the applicable scenarios of steel pipe pile demolition technology. Attached Figure Description

[0013] Figure 1 This is a simplified schematic diagram of the construction process in an embodiment of the present invention; Figure 2 This is a schematic diagram of the method steps in an embodiment of the present invention; Figure 3 This is a schematic diagram of the construction site in an embodiment of the present invention. Detailed Implementation

[0014] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings. It should be noted that the description of these embodiments is for the purpose of helping to understand the present invention, but does not constitute a limitation of the present invention.

[0015] Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0016] Please see the appendix Figure 1 -Appendix Figure 3 This invention discloses a method for dismantling steel pipe piles that combines helical disturbance and vibration extraction. The method includes the following steps: Step 1: Complete the pre-construction survey and standardized pre-treatment of the pile perimeter, identify the distribution of underground obstacles around the pile, delineate the safe working area and spiral disturbance boundary, and simultaneously complete the pile top cleaning, annular diversion trench excavation and high-pressure pre-washing of the pile-soil interface. Step 2: Coaxially install the hollow spiral drill rod with high-pressure water injection system on the outside of the steel pipe pile to be demolished, and complete the installation and multi-system linkage debugging of the spiral disturbance system and the pile top hydraulic vibration extraction system. Step 3: Drive the auger drill rod to rotate counterclockwise along the outer wall of the steel pipe pile and drill downwards. During the drilling process, high-pressure water is injected into the pile-soil interface to form a continuous annular disturbance and drag reduction zone and a closed-loop lubricating mud sleeve around the pile. Step 4: After drilling to the designed pile bottom elevation, maintain pressure and stabilize the drill to complete the targeted softening of the soil at the pile tip and the drag reduction and strengthening of the entire pile length. Keep the auger rod rotating in place and the high-pressure water injection state uninterrupted throughout the process. Step 5: While maintaining in-situ disturbance of the auger drill rod and high-pressure water injection, start the vibratory hammer to apply high-frequency low-amplitude vibration, and adopt a segmented uniform speed extraction method. Through the coordinated operation of disturbance and extraction, the steel pipe pile is extracted smoothly with low resistance. Step 6: Monitor the pile extraction status in real time during the operation, and execute the graded emergency response procedure when a pile jamming failure is triggered; Step 7: After completing the integrity acceptance of the extracted pile, dismantle and remove the equipment and backfill and compact the pile hole in layers. Example

[0017] This embodiment applies to the demolition of temporary support steel pipe piles for deep foundation pits in urban core areas. Specific working parameters are as follows: The steel pipe piles to be demolished are 609mm×16mm straight seam steel pipe pile, single pile penetration depth 15m, pile top elevation +0.5m, pile bottom elevation -14.5m, single pile self-weight approximately 36kN; The soil layers around the pile, from top to bottom, are as follows: ① Plain fill soil (layer thickness 2m, ultimate lateral friction resistance 20kPa), ② Soft plastic silty clay (layer thickness 6m, ultimate lateral friction resistance 30kPa), ③ Hard plastic silty clay (layer thickness 7m, ultimate lateral friction resistance 45kPa). The bearing stratum at the pile tip is stiff silty clay, with an ultimate bearing capacity of 600 kPa. Construction surrounding environment: There is an existing 6-story brick-concrete residential building 3m outside the pile body, and municipal water supply and gas pipelines are distributed within 2m of the pile body. It is an area that is extremely sensitive to construction disturbance. The design requires that the peak value of the vibration velocity of the surrounding soil particles should not exceed 0.3cm / s.

[0018] This embodiment employs the steel pipe pile demolition method described in this invention, and the specific implementation steps are as follows: Step 1: Pre-construction survey and standardized pre-treatment around the pile: First, a 500MHz ground-penetrating radar combined with a manual test pit is used to comprehensively investigate the distribution, burial depth and planar position of underground pipelines and existing building foundations within a 3m radius around the steel pipe pile to be demolished. With the axis of the steel pipe pile as the center, a ring-shaped spiral disturbance operation boundary with an outer diameter of 1200mm and a safe operation zone with an outer diameter of 6m are demarcated. At the same time, the operation site is leveled and hardened to ensure that the bearing capacity of the foundation for equipment installation is not less than 100kPa. Subsequently, an angle grinder was used to remove debris, rust, and deformed parts from the top flange and stiffening ribs of the steel pipe pile to ensure that the flatness deviation of the clamping device's contact surface does not exceed 1mm. Within the boundary of the disturbance operation, a ring-shaped diversion ditch is excavated around the steel pipe pile, with a depth of 150mm and a width of 200mm. Finally, a high-pressure water gun with a fan-shaped nozzle is used to perform circumferential pre-rinsing along the pile-soil interface. The high-pressure water pressure is controlled at 15MPa, and the nozzle spray direction is at a 30° angle to the pile axis, pointing obliquely downwards towards the pile-soil interface. The nozzle moves at a uniform speed around the pile to complete the full-section pre-rinsing, thus pre-softening the surface soil around the pile.

[0019] Step 2: Installation and linkage debugging of the spiral disturbance and pile extraction coordinated operation system: Select a hollow spiral drill rod with an inner diameter of 650mm, and coaxially sleeve it on the outside of the steel pipe pile to be demolished. The inner diameter of the drill rod is 41mm larger than the outer diameter of the steel pipe pile. Four sets of circumferentially evenly distributed guide rollers are set on the inner wall of the guide cone at the lower end of the spiral drill rod. The gap between the guide rollers and the outer wall of the steel pipe pile is controlled at 3mm to ensure that the coaxiality deviation between the drill rod and the pile body does not exceed 3‰ during the drilling process. Spiral blades are welded to the outer wall of the auger drill rod. The blade pitch is 150mm and the outer diameter of the blade is 900mm, which is 291mm larger than the outer diameter of the steel pipe pile. The upper end of the auger rod is rigidly connected to the output shaft of the hydraulic drive head via a flange. The hydraulic drive head is fixed on a liftable guide bracket with a vertical slide rail. The verticality deviation of the guide bracket is controlled within 2‰. Simultaneously, the 450-type hydraulic vibratory hammer is installed on the top of the steel pipe pile using a special hydraulic wedge clamp. The inner wall of the clamp claw is embedded with anti-slip toothed plates, and the clamping force is set to 60kN (not less than 1.5 times the self-weight of the steel pipe pile). Finally, the linkage debugging of the spiral disturbance system, vibration removal system, high-pressure water injection system and real-time monitoring system was completed, and the action sequence, parameter acquisition frequency and emergency trigger logic of each system were calibrated.

[0020] Step 3: Combined pre-disturbance of spiral drilling and high-pressure water injection: Start the hydraulic drive power head and drive the spiral drill rod to drill downward along the outer wall of the steel pipe pile in a counter-rotating manner. The counter-rotation direction matches the soil conveying direction of the spiral blades, so that the cut soil is continuously transported upward along the spiral channel to the surface diversion ditch. During the drilling process, the drilling speed is dynamically adjusted according to the soil layers. The drilling speed in the plain fill and soft plastic silty clay layers is controlled at 0.8 m / min, while the drilling speed in the hard plastic silty clay layer is reduced to 0.3 m / min. During the drilling process, the high-pressure water injection system is started simultaneously. High-pressure water is injected into the pile-soil interface through high-pressure nozzles set longitudinally at intervals on the inner wall of the drill rod. The water injection pressure is dynamically controlled at 20MPa, and the water injection flow rate is set at 20L / min per meter of pile length. A continuous annular disturbance and drag reduction zone and a closed-loop lubricating mud sleeve are formed around the pile. Throughout the drilling process, the output torque of the power head and the water injection pressure are monitored in real time. When the torque exceeds 80% of the set threshold, the drilling speed is automatically reduced and the water injection pressure is increased.

[0021] Step 4, Targeted softening of pile tip and drag reduction and strengthening of the whole pile length: After the hollow auger drill rod is drilled to the design elevation of the pile bottom -14.5m, the vertical feed of the drill rod is stopped, and the pressure holding and drilling operation is carried out in the reverse rotation state. The drilling speed is consistent with the drilling speed, and the drilling time is set to 2min. During the drilling process, the water injection pressure is kept stable at 25MPa, so that the high-pressure water can spread fully along the pile-soil interface to the bottom of the pile tip, softening the soil of the bearing layer at the pile tip. Simultaneously, through the continuous rotation of the drill rod, secondary cutting and disturbance are carried out on the annular disturbance zone along the entire pile length, high-pressure water and mud medium are replenished, the closed-loop lubricating mud sleeve is repaired, and after drag reduction and strengthening are completed, the auger drill rod is kept in place and the high-pressure water injection state is maintained without interruption.

[0022] Step 5, Coordinated removal operation while disturbing: While the auger rod is rotating in place and high-pressure water is injected, start the hydraulic vibratory hammer to carry out the coordinated removal operation. The vibration frequency is set to 30Hz and the amplitude is set to 5mm. These parameters avoid the natural frequencies of the surrounding soil and existing buildings. First, calculate the theoretical ultimate pull-out resistance of the steel pipe pile. The calculation formula is as follows: ; Among them, the total surface area of ​​the pile side =π×0.609×15≈28.69m 2 Weighted average unit side friction resistance =(2×20+6×30+7×45) / 15≈35.67kPa, circumferential bearing area at the pile tip =π×(0.6092−0.5772) / 4≈0.0298m 2 ultimate bearing capacity of pile tip =600kPa, calculated theoretical ultimate pile extraction resistance =35.67×28.69+600×0.0298≈1041.4kN; The maximum excitation force of the vibratory hammer is set to 1.8 times the theoretical value, i.e., 1874.5 kN; The segmented uniform speed extraction method is adopted, with the single extraction length set at 0.5m. Vibration is paused after each segment is completed to check and calibrate the verticality of the pile and the condition of the clamp. Throughout the extraction process, while the vibratory hammer is pulling out the material, the auger rod maintains a low-speed rotation and constant high-pressure water injection. The vibratory hammer pauses to calibrate the gap, while the auger drill rod increases its rotation speed and water injection pressure to supplement disturbance and mud lubrication. Through the coordinated operation of disturbing and pulling simultaneously, the steel pipe pile is pulled out smoothly and completely without any jamming.

[0023] Step 6: Real-time monitoring of the construction process: During the operation of this embodiment, the pile extraction resistance, vibratory hammer load rate and pile extraction speed were monitored in real time. All parameters were within the set threshold range and the pile jamming emergency response procedure was not triggered.

[0024] Step 7, Acceptance and Departure and Pile Hole Backfilling: After the steel pipe piles are completely pulled out, check and confirm that the pile body is intact without any breaks or residual sections. Simultaneously, clean up the mud on the working surface and level the site. Disassemble each piece of equipment in sequence, inspect and maintain it, and then leave the site in an orderly manner. Graded sand and gravel were used to backfill and compact the pile holes in layers, with each layer being 250mm thick and the compaction coefficient being no less than 0.93. After backfilling, the ground surface was leveled and hardened, and all demolition work was completed.

[0025] The final implementation results of this embodiment are as follows: the actual monitored maximum pile extraction resistance is 410kN, which is 60.6% lower than the theoretical limit; the peak vibration velocity of the surrounding soil particles is 0.22cm / s, which meets the control requirement of 0.3cm / s in sensitive areas; the total demolition time for a single pile is 2.5 hours, with no pile jamming or breakage throughout the process; the maximum load rate of the vibratory hammer is only 45%, and the equipment operates smoothly. Example

[0026] This embodiment applies to the demolition of steel pipe piles for the renovation of existing berths at port terminals. Specific working parameters are as follows: The steel pipe piles to be demolished are 1200mm×20mm spiral joint steel pipe pile, single pile penetration depth 35m, pile top elevation +2.0m, pile bottom elevation -33.0m, single pile self-weight approximately 207kN; The soil layers around the pile, from top to bottom, are as follows: ① Plain fill (layer thickness 3m, ultimate lateral friction resistance 25kPa), ② Medium-dense silty sand (layer thickness 8m, ultimate lateral friction resistance 35kPa), ③ Stiff plastic silty clay (layer thickness 15m, ultimate lateral friction resistance 50kPa), ④ Dense coarse sand (layer thickness 9m, ultimate lateral friction resistance 65kPa); The bearing layer at the pile tip is dense coarse sand, with an ultimate end bearing capacity of 2000kPa; Construction surrounding environment: There is an existing wharf gravity retaining wall 5m outside the pile body. Strict control of construction vibration and soil disturbance is required. The design requires that the peak vibration velocity of the surrounding soil particles must not exceed 0.5cm / s.

[0027] This embodiment uses the steel pipe pile demolition method described in this invention. The core implementation steps are the same as in Embodiment 1, and the key process parameters are adjusted to suit the working conditions as follows: In step one, the high-pressure pre-rinsing pressure is set to 18MPa, and the guide channel depth is 200mm and the width is 300mm; In step two, the inner diameter of the hollow spiral drill rod is 1240mm, which is 40mm larger than the outer diameter of the steel pipe pile. The outer diameter of the spiral blade is 1500mm, which is 300mm larger than the outer diameter of the steel pipe pile. The blade pitch is 200mm. The clamping force of the clamp is set to 320kN. In step three, the drilling speed in soft soil and sand layers is controlled at 0.5 m / min, and the drilling speed in hard plastic clay and dense sand layers is controlled at 0.2 m / min. The water injection pressure is dynamically controlled at 25 MPa-30 MPa, and the water injection flow rate is set at 30 L / min per meter of pile length. In step four, the stabilization time is set to 3 minutes, and the water injection pressure is kept stable at 30 MPa during the stabilization process. In step five, the vibration frequency was set to 25Hz and the amplitude to 6mm. The theoretical ultimate pile extraction resistance was calculated. The maximum excitation force of the vibratory hammer is set to 2.0 times the theoretical value, i.e., 9785.2kN, and the single pulling length is set to 1.0m.

[0028] The final implementation results of this embodiment are as follows: the actual monitored maximum pile extraction resistance is 1850kN, which is 62.2% lower than the theoretical limit value; the peak vibration velocity of the surrounding soil particles is 0.36cm / s, which meets the control requirement of 0.5cm / s for the wharf area; the total construction period for single pile removal is 8 hours, and no pile jamming or breakage occurs throughout the process. The equipment operates smoothly, and the construction process has no adverse impact on the existing wharf structure.

[0029] Comparative Example This comparative example uses the exact same steel pipe pile parameters, soil conditions, surrounding environment, and control requirements as Example 2. The only difference is that it adopts the conventional step-by-step process of "first helical pre-disturbance, then vibration extraction" in the existing technology. The specific implementation steps are as follows: Complete the pile perimeter survey and pretreatment work that is completely consistent with Example 2; The same spiral disturbance device as in Example 2 was used and coaxially sleeved on the outside of the steel pipe pile to complete the installation and commissioning. Drive the auger drill rod to rotate in the opposite direction and drill to the designed elevation of the pile bottom. High-pressure water is injected simultaneously during the drilling process. The drilling parameters are completely consistent with those in Example 2. After drilling is completed, stop the high-pressure water injection and pull the auger drill rod out of the pile perimeter working area at a uniform speed. The same hydraulic vibratory hammer as in Example 2 was used and installed on the top of the steel pipe pile. The vibration parameters and excitation force settings were exactly the same as in Example 2. The same segmented extraction method was used to complete the steel pipe pile extraction operation. If a pile gets stuck during operation, the method of increasing the excitation force to forcibly pull it out shall be used to deal with the situation; After the steel pipe piles are pulled out, the acceptance, removal and backfilling of the pile holes are carried out in exactly the same manner as in Example 2.

[0030] The final implementation results of this comparative example are as follows: the actual monitored maximum pile extraction resistance was 3960kN, which was only 19.1% lower than the theoretical limit; the peak vibration velocity of the surrounding soil particles was 0.87cm / s, exceeding the control limit of 0.5cm / s for the wharf area; two pile jamming accidents occurred during construction, forcing the machine to stop for disposal, and the total construction period for single pile removal was 18 hours; the maximum load rate of the vibratory hammer reached 92%, and the equipment was in an overloaded state for a long time, posing a significant safety hazard.

[0031] Comparative Analysis of Examples and Comparative Examples The core performance indicators of Examples 1 and 2 and the comparative examples are summarized and compared, and the results are shown in Table 1 below:

[0032] Table 1: Comparison of Parameters between Examples and Comparative Examples

[0033] The comparison results show that the steel pipe pile removal method of the present invention can reduce the pile extraction resistance by more than 60%, increase the construction efficiency by more than 100%, reduce the surrounding construction vibration by more than 50%, eliminate pile jamming accidents throughout the process, and significantly reduce the equipment load rate. It completely solves the core defects of the existing technology, such as unsustainable resistance reduction effect, inability to balance resistance reduction and disturbance control, and poor construction reliability. It has outstanding substantive features and significant technological progress.

[0034] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Any variations and modifications can be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, any modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention, without departing from the scope of the invention, fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for demolishing steel pipe piles combining helical disturbance and vibration extraction, characterized in that, The method for removing steel pipe piles includes the following steps: Step 1: Complete the pre-construction survey and standardized pre-treatment of the pile perimeter, identify the distribution of underground obstacles around the pile, delineate the safe working area and spiral disturbance boundary, and simultaneously complete the pile top cleaning, annular diversion trench excavation and high-pressure pre-washing of the pile-soil interface. Step 2: Coaxially install the hollow spiral drill rod with high-pressure water injection system on the outside of the steel pipe pile to be demolished, and complete the installation and multi-system linkage debugging of the spiral disturbance system and the pile top hydraulic vibration extraction system. Step 3: Drive the auger drill rod to rotate counterclockwise along the outer wall of the steel pipe pile and drill downwards. During the drilling process, high-pressure water is injected into the pile-soil interface to form a continuous annular disturbance and drag reduction zone and a closed-loop lubricating mud sleeve around the pile. Step 4: After drilling to the designed pile bottom elevation, maintain pressure and stabilize the drill to complete the targeted softening of the soil at the pile tip and the drag reduction and strengthening of the entire pile length. Keep the auger rod rotating in place and the high-pressure water injection state uninterrupted throughout the process. Step 5: While maintaining in-situ disturbance of the auger drill rod and high-pressure water injection, start the vibratory hammer to apply high-frequency low-amplitude vibration, and adopt a segmented uniform speed extraction method. Through the coordinated operation of disturbance and extraction, the steel pipe pile is extracted smoothly with low resistance. Step 6: Monitor the pile extraction status in real time during the operation, and execute the graded emergency response procedure when a pile jamming failure is triggered; Step 7: After completing the integrity acceptance of the extracted pile, dismantle and remove the equipment and backfill and compact the pile hole in layers.

2. The method for demolishing steel pipe piles combining helical disturbance and vibration extraction according to claim 1, characterized in that: In step one, the specific steps are as follows: First, ground-penetrating radar combined with manual pit exploration is used to identify the distribution, burial depth, and planar location of underground pipelines, existing structural foundations, and underground obstacles within a 3m radius around the steel pipe pile to be demolished. Based on the survey results, a ring-shaped safe working area and a spiral disturbance working boundary are delineated with the steel pipe pile axis as the center. The work site is leveled and the bearing capacity is reinforced simultaneously. Then, debris, rust, and deformed parts of the flange and stiffening rib of the top flange of the steel pipe pile are removed. Within the delineated spiral disturbance working boundary, a ring-shaped shallow diversion ditch is excavated around the steel pipe pile. The depth of the diversion ditch is controlled at 100mm-200mm, and the width is controlled at 150mm-300mm. Finally, a high-pressure water gun with a fan-shaped nozzle is used to perform circumferential pre-rinsing along the interface between the steel pipe pile and the soil. The high-pressure water pressure is precisely controlled at 10MPa-20MPa, and the nozzle spray direction is obliquely downwards towards the interface between the pile and the soil. The entire cross-section is pre-rinsed by moving at a uniform speed around the pile.

3. The method for demolishing steel pipe piles combining helical disturbance and vibration extraction according to claim 1, characterized in that: In step two, specifically: a hollow spiral drill rod with a high-pressure water injection system is coaxially fitted onto the outside of the steel pipe pile to be demolished. The inner diameter of the spiral drill rod is 20mm-50mm larger than the outer diameter of the steel pipe pile. The inner wall of the guide cone at the lower end of the spiral drill rod is equipped with guide rollers evenly distributed circumferentially along the outer wall of the steel pipe pile. The gap between the guide rollers and the outer wall of the steel pipe pile is controlled at 2mm-5mm. Then, the upper end of the spiral drill rod is rigidly connected to the output shaft of the hydraulic drive power head through a flange connection. The hydraulic power head is fixedly installed on a liftable guide bracket with a vertical slide rail. The verticality deviation of the guide bracket does not exceed 2‰. Simultaneously, the hydraulic vibratory hammer is installed on the top of the steel pipe pile through a hydraulic wedge clamp. The inner wall of the clamp claw is embedded with anti-slip teeth. The clamping force is set to be no less than 1.5 times the self-weight of the steel pipe pile. Finally, the linkage debugging of the spiral disturbance system, vibration extraction system, high-pressure water injection system and real-time monitoring system is completed, and the action sequence, parameter feedback and emergency trigger logic of each system are calibrated.

4. The method for demolishing steel pipe piles combining helical disturbance and vibration extraction according to claim 1, characterized in that: Step three specifically involves: after system debugging, starting the hydraulic drive head to drive the hollow spiral drill rod to drill vertically downwards along the outer wall of the steel pipe pile in a counter-rotating manner. The counter-rotation direction matches the soil conveying direction of the spiral blades on the outer wall of the spiral drill rod, so that the spiral blades continuously transport the cut soil upwards along the spiral channel to the surface diversion ditch during rotation. During drilling, the drilling speed is dynamically adjusted according to the engineering characteristics of the soil layers around the pile. In soft plastic-fluid plastic clay layers, the drilling speed is controlled at 0.5m / min-1.0m / min, and in hard plastic clay layers, medium-dense and dense sand layers, the drilling speed is reduced to 0.2m / min-0.5m / min. During drilling, the high-pressure water injection system is started simultaneously, through the spiral... High-pressure water injection nozzles are set longitudinally along the inner wall of the rotary drill rod to continuously inject high-pressure water into the soil interface of the steel pipe pile. The water injection pressure is dynamically controlled between 15MPa and 30MPa according to the soil permeability and the pile's surrounding constraints. The water injection flow rate is set at 10L / min to 30L / min per meter of pile length. A continuous and uniform annular disturbance and drag reduction zone and a closed-loop lubricating mud sleeve are formed around the steel pipe pile. The outer diameter of the annular disturbance and drag reduction zone is 150mm to 300mm larger than the outer diameter of the steel pipe pile. Throughout the drilling process, the output torque of the hydraulic power head, the vertical feed force, and the pressure and flow parameters of the high-pressure water injection system are monitored in real time. When the output torque is detected to exceed 80% of the set threshold, the drilling speed is automatically reduced and the water injection pressure is increased.

5. The method for demolishing steel pipe piles combining helical disturbance and vibration extraction according to claim 1, characterized in that: In step four, specifically: after the hollow auger drill rod has reverse-drilled to the designed pile bottom elevation of the steel pipe pile, the vertical feed of the drill rod is stopped, and the auger drill rod is kept in a reverse rotation state at the designed depth position for pressure holding and stabilizing drilling operations. The stabilizing drilling rotation speed is consistent with the rotation speed during the drilling process, and the stabilizing drilling time is controlled between 1 minute and 3 minutes. During the stabilizing drilling process, the working state of the high-pressure water injection system is continuously maintained, and the water injection pressure is stabilized at the upper limit value during the drilling process, so that the high-pressure water continuously diffuses along the pile-soil interface to the bottom of the steel pipe pile end, fully softening the soil of the bearing layer at the pile end. At the same time, through the continuous rotation of the auger drill rod, the annular disturbance and drag reduction zone around the entire pile length is subjected to secondary cutting disturbance, and high-pressure water and mud medium are replenished to repair the closed-loop lubricating mud sleeve. After completing the stabilizing drilling and drag reduction strengthening operations, the in-situ rotation of the auger drill rod and the high-pressure water injection state are kept uninterrupted.

6. The method for demolishing steel pipe piles combining helical disturbance and vibration extraction according to claim 1, characterized in that: In step five, specifically: while the hollow spiral drill rod remains in place and continues to rotate in reverse while high-pressure water is injected, a hydraulic vibratory hammer is activated to perform a coordinated extraction operation. The vibratory hammer applies high-frequency, low-amplitude vertical vibration to the steel pipe pile, with the vibration frequency precisely controlled between 20Hz and 40Hz and the amplitude controlled between 2mm and 8mm. The maximum excitation force of the vibratory hammer is set according to the theoretical ultimate extraction resistance of the steel pipe pile, and the maximum excitation force is taken as 1.5 to 2.0 times the theoretical ultimate extraction resistance. The theoretical ultimate extraction resistance is calculated using the following formula: ； in, This represents the theoretical ultimate pull-out resistance of the steel pipe pile, expressed in kN. The ultimate side friction resistance per unit area of ​​each soil layer around the pile, expressed in kPa. This refers to the total surface area of ​​the steel pipe pile side, in m². 2 , This represents the ultimate bearing capacity per unit area of ​​the pile tip bearing layer, expressed in kPa. This refers to the annular bearing area at the pile tip of the steel pipe pile, expressed in m². 2 The vibratory extraction adopts a segmented, uniform-speed extraction method. The single extraction length of each segment is controlled between 0.5m and 1.0m. After each segment is extracted, the vibration and extraction actions are paused to check and calibrate the verticality of the steel pipe pile and the installation status of the clamp. Throughout the extraction process, the auger and vibratory hammer maintain a strict coordinated working sequence. When the vibratory hammer starts vibrating and vertically extracting, the auger maintains low-speed reverse rotation and constant high-pressure water injection. During the interval when the vibratory hammer pauses extraction for attitude calibration, the auger increases its rotation speed and water injection pressure. Through a closed-loop operation mode of simultaneous disturbance and extraction, the steel pipe pile is smoothly extracted until the entire steel pipe pile is completely detached from the pile hole.

7. The method for demolishing steel pipe piles combining helical disturbance and vibration extraction according to claim 1, characterized in that: In step six, during the extraction operation, real-time data on pile extraction resistance, vibratory hammer excitation load rate, and pile extraction speed are continuously collected by a real-time monitoring system. When any one of the following three conditions is detected: pile extraction resistance exceeding the set limit threshold, vibratory hammer excitation load rate continuously exceeding 90%, or no effective extraction displacement of the pile for 5 consecutive seconds, the system automatically determines it as a stuck pile fault and triggers a tiered emergency response process. First, a level one emergency response is executed: the vibratory hammer vibration and extraction operation are immediately suspended, while the in-situ rotation of the auger rod and high-pressure water injection are maintained uninterrupted. The reciprocating bidirectional rotation function of the auger rod is activated, controlling the hydraulic power head to alternately rotate forward and reverse. The duration of each forward and reverse rotation is controlled between 10 and 30 seconds, with the rotation speed consistent with the drilling process. The outer diameter of the disturbance zone is increased by 100-200 mm, and the water injection pressure of the high-pressure water injection system is simultaneously increased to 30-40 MPa. The pressure and water flow rate are increased to 1.5 to 2.0 times the original set value. Pulse water injection is used to impact the pile-soil interface. If the pile extraction resistance is still not reduced to within the set threshold after the first-level emergency treatment, the second-level emergency treatment is implemented. Based on the first-level treatment, one of bentonite or polymer mud material is added to the water in the high-pressure water injection system. The viscosity of the prepared mud is controlled at 30s-60s. The stable drilling time of the bidirectional reciprocating rotation is extended to 3min-5min. After the treatment is completed, the vibration extraction operation is restarted. If effective extraction cannot be achieved after two or more second-level emergency treatments, the third-level emergency treatment is implemented. First, the entire spiral drill rod is pulled upward at a uniform speed out of the steel pipe pile working area. Then, the core soil is extracted from the inside of the steel pipe pile using either a percussion cone or a soil scavenging drill. After the core soil is extracted, the spiral disturbance device is reinstalled, and the disturbance resistance reduction and coordinated extraction operation is repeated until the steel pipe pile is completely extracted.

8. The method for demolishing steel pipe piles combining helical disturbance and vibration extraction according to claim 1, characterized in that: In step seven, after the steel pipe pile is completely extracted, the integrity of the extracted steel pipe pile is first checked to confirm that there are no broken sections or residual segments left in the pile hole. Simultaneously, the mud cleaning, debris removal, and site leveling of the work surface are completed. Then, the spiral disturbance device, hydraulic vibratory hammer, and supporting auxiliary equipment are disassembled in sequence. After the equipment is inspected and maintained, they are removed from the site in an orderly manner. Finally, the pile hole formed after the steel pipe pile is extracted is backfilled in a standardized manner. According to the site usage requirements and geological conditions around the pile hole, graded sand and gravel and cement-soil mixture are used for layered backfilling and compaction. The thickness of each backfill layer is controlled at 200mm-300mm, and the layer compaction coefficient is not less than 0.

93. After the backfilling is completed, the surface at the top of the pile hole is leveled and hardened, completing the entire process of steel pipe pile removal.

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