Environment-friendly ultra-deep soft soil layer cast-in-place pile construction method and recoverable device

Abstract

The invention relates to an environment-friendly ultra-deep soft soil layer cast-in-place pile construction method and an energy recovery device. The environment-friendly ultra-deep soft soil layer cast-in-place pile construction device comprises a double-layer pile casing, a drilling machine, a slurry system and the energy recovery device. The construction method comprises the construction steps of site preparation and lofting, pile casing burying, drilling machine in-place and drilling bucket installation, pore-forming drilling and grouting wall protection, closed-circuit slurry purification and reinjection, hole cleaning detection, reinforcement cage lowering and positioning, guide pipe pouring and pile casing recycling. According to the method, drilling machine hydraulic system braking energy and motor braking energy are recovered in real time through an energy recovery device, energy recovery and supply are dynamically adjusted through a self-adaptive distribution algorithm based on real-time working condition data of a monitoring system, and energy saving and consumption reduction are achieved. The system has the advantages of remarkable energy conservation, high pile forming quality, high adaptability, high intelligent degree and the like, and is suitable for pile foundation construction of ultra-deep soft soil layers.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of pile foundation construction technology in geotechnical engineering, in particular to an energy-saving and environment-friendly super-deep soft soil layer cast-in-place pile construction method and a back energy device used thereby. BACKGROUND

[0002] With the continuous expansion of infrastructure construction to coastal, river and delta areas, pile foundation construction under super-deep soft soil layer conditions is increasingly common. As the mainstream foundation form for such geological conditions, the construction process of cast-in-place piles usually relies on heavy equipment such as high-power hydraulic drilling machines, mud pumps and vibration hammers, resulting in high energy consumption and energy waste. Under the background of the "double carbon" strategy, the demand for energy saving and consumption reduction in the pile foundation construction industry is increasingly urgent.

[0003] Currently, the conventional cast-in-place pile construction method has inherent defects in energy utilization. During the drilling machine drilling, lifting of the drill bucket and vibration hammer operation, the hydraulic system is frequently started and stopped and reversed. When the hydraulic motor or oil cylinder needs to be decelerated or braked, its inertial kinetic energy is usually converted into heat energy through the throttling action of the hydraulic valve and directly dissipated into the environment. This throttling loss not only causes a large amount of energy waste, but also causes the oil temperature of the hydraulic system to rise, accelerating the aging of the oil, reducing the reliability of the system and increasing the energy consumption of the cooling system. Similarly, the motor driving the drilling machine, sand pump and other equipment has a large power, and the purification equipment such as ZX-250 mud separator usually needs to be equipped with a 55kW slurry pump. When decelerating or braking, the rotating kinetic energy of the motor is usually consumed through a resistor, and since the power of these devices is very large, if not recovered, it will result in a waste of electrical energy and huge losses.

[0004] Although some technologies have attempted to recover energy during construction, most have systemic deficiencies. For example: The specification of publication number CN106545534A discloses "recycling the potential energy of the lowering of the working device 4 through the energy recovery motor 7, and then converting the recycled potential energy into electrical energy through the generator 8, and storing it through the super capacitor 10, which can be electrically connected to the electrical device, realizing the recycling of potential energy under continuous cyclic operation conditions through the electro-hydraulic mode, and using the recycled energy to drive the electrical device, which can realize the continuous recycling and reuse of potential energy", but the potential energy needs to be converted through multiple energy conversions, i.e. potential energy-energy recovery motor kinetic energy-generator kinetic energy-electrical energy, with low conversion efficiency.

[0005] In summary, existing technologies either lack energy recovery methods or employ singular, isolated recovery schemes lacking intelligent collaboration, failing to form a complete systematic solution for energy recovery, storage, and reuse. This results in low energy utilization efficiency during cast-in-place pile construction, falling far short of current green and low-carbon construction requirements. Therefore, developing a cast-in-place pile construction method capable of systematically recovering various braking energies generated during construction, intelligently allocating and prioritizing their supply based on real-time operating conditions, and significantly reducing energy consumption and carbon emissions has become an urgent technical challenge to be solved in this field. Summary of the Invention

[0006] The purpose of this invention is to overcome the aforementioned deficiencies of the prior art and provide an energy-saving and environmentally friendly method for constructing cast-in-place piles in ultra-deep soft soil layers. This method integrates an intelligent energy recovery device and a closed-loop control system to effectively recover the hydraulic energy and motor braking energy generated during construction and supply them to the equipment as needed, thereby significantly reducing energy consumption and achieving green construction.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A method for constructing cast-in-place piles in ultra-deep soft soil layers, characterized by energy-saving and environmentally friendly construction, includes a double-layer casing, a drilling rig, a mud system, and a regenerative braking device, and is characterized by construction in steps: a. Site preparation and layout: Level and compact the construction site, and start the monitoring system to record the baseline geological parameters; b. Installation of casing: The double-layer casing is pressed into the soft soil layer in sections using a vibratory hammer. The casing includes an outer casing and an inner casing. The diameter of the outer casing is approximately 50 cm larger than the designed pile diameter, and the diameter of the inner casing is approximately 20 cm larger than the designed pile diameter. The installation depth is determined according to the geological conditions. c. Drilling rig positioning and drill bucket installation: Position the drilling rig and install the drill bucket, which is a heightened double-door, double-bottom, high-angle cylindrical bucket with an exhaust port at the top; d. Hole drilling and grouting: Drilling is carried out in a segmented rotary drilling manner under the adjustable torque condition of the drilling rig. The grouting system is used to inject grouting mud into the hole to maintain the stability of the hole wall. When decelerating, the energy recovery device is activated to recover hydraulic energy. The hydraulic energy recovered by the energy recovery device adaptively provides the torque of the hydraulic motor according to the monitored real-time power demand signal. e. Closed-circuit mud purification and reinjection: The sand-containing mud in the borehole is pumped to the purification device by a sand pump. After being processed by units such as coarse screening, centrifugal separation and automatic chemical dosing and flocculation, the purified mud is reinjected into the borehole for recycling and the discharge rate is controlled to be less than 10% of the total usage. When decelerating, the energy recovery device is activated to recover the residual braking energy of the motor. The residual motor energy recovered by the energy recovery device adaptively provides electrical energy according to the monitored real-time power demand signal. f. Hole cleaning and inspection: After drilling reaches the designed depth, reverse circulation or mud replacement hole cleaning process is carried out, and sediment at the bottom of the hole is removed. The hole diameter, hole depth, mud specific gravity and sand content are monitored and tested until the design requirements are met. g. Lowering and positioning the reinforcing cage: Fabricate and lower the reinforcing cage, and use a positioning frame to ensure that the reinforcing cage is centered and meets the protective layer thickness requirements; h. Conduit grouting and casing recovery: The conduit is used for continuous underwater concrete grouting. During the grouting process, the conduit is pulled out in sections. When deceleration occurs, the energy recovery device is activated to recover hydraulic energy. The hydraulic energy recovered by the energy recovery device adaptively provides the torque of the hydraulic motor according to the monitored real-time power demand signal.

[0008] Preferably, the drill bucket is a double-door, double-bottom, high-angle sand-scooping drill bucket with additional exhaust holes at the top.

[0009] Preferably, the diameter of the drill bucket is 2-4 cm smaller than the diameter of the pile to be constructed, and the outside of the drill bucket is provided with fine cutting teeth to improve the mud mobility on the outside of the bucket, reduce negative pressure, reduce bucket sticking, improve air release, reduce the risk of diameter reduction and hole collapse, and effectively improve construction quality and efficiency.

[0010] Preferably, the purification device includes a sand pump, a coarse screen, and a centrifugal separator.

[0011] Preferably, the energy recovery device is connected to the monitoring system via a data link. The energy recovery device executes an adaptive allocation algorithm in real time based on the torque, pump power, and vibratory hammer status output by the monitoring system to dynamically adjust the hydraulic recovery and electrical energy feedback ratio and supply energy according to priority.

[0012] Preferably, the outer and inner casings of the double-layer casing are coaxially arranged, and a spacer ring and a grouting port are provided between the outer and inner casings.

[0013] Preferably, the energy recovery device includes a hydraulic accumulator, a motor braking module, an electrical energy storage unit, an inverter module, and a control unit. The hydraulic accumulator is connected to the hydraulic circuit. The motor braking module is electrically connected to the electrical energy storage unit, the inverter module, and the control unit. The control unit is electrically connected to the hydraulic accumulator. When the hydraulic motor deceleration is detected, the hydraulic circuit is automatically switched to store hydraulic energy in the hydraulic accumulator. When the drill rig motor deceleration is detected, the electrical energy generated by the motor rotation is processed by the motor braking module and stored in the electrical energy storage unit. The electrical energy storage unit supplies power to the drilling rig through the inverter module.

[0014] Preferably, the energy storage unit is a combined energy storage unit, including a supercapacitor for short-term high-power recovery and a lithium-ion battery for medium- to long-term energy storage, and is equipped with a charge management unit to optimize charging and discharging.

[0015] Preferably, the hydraulic accumulator is equipped with an adjustable check valve and a pressure tank to recover hydraulic energy during the drilling deceleration phase.

[0016] Preferably, the control unit consists of a PLC, which can automatically detect the deceleration phase of the drilling rig and control the energy recovery device to recover hydraulic and electrical energy.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Significant energy saving effect: Through the energy recovery device, the braking energy of the drilling rig hydraulic system and the motor braking energy are systematically recovered, and the recovered energy is used for auxiliary drive equipment, which significantly reduces the energy consumption of the external power grid. The overall energy saving rate is expected to reach more than 20%.

[0018] 2. Good environmental performance: The closed-loop mud circulation system controls the amount of mud discharged to less than 10%, reducing the pollution of the environment caused by mud discharge; at the same time, energy recovery indirectly reduces carbon emissions, which meets the requirements of green construction.

[0019] 3. High adaptability and intelligence: Based on the real-time data of the monitoring system, the energy flow is dynamically managed through the adaptive algorithm of the control unit, realizing precise matching of recovery and energy supply, and ensuring the smooth and efficient construction process.

[0020] 4. High pile quality: The double-layer casing structure, efficient drill bit design, and strict hole cleaning and inspection process jointly ensure the stability of hole formation in ultra-deep soft soil layers and the construction quality of the final cast-in-place piles. Attached Figure Description

[0021] Figure 1 This is a process flow diagram of the construction method described in this invention.

[0022] Figure 2 This is a structural plan view of the double-layer casing described in this invention.

[0023] Figure 3 This is a sectional plan view of the double-layer casing described in this invention.

[0024] Figure 4 This is a schematic diagram of the structure of the drill bucket described in this invention.

[0025] Figure 5 This is a block diagram illustrating the hydraulic system energy recovery principle of the energy recovery device described in this invention.

[0026] Figure 6 This is a block diagram illustrating the power system energy recovery principle of the energy recovery device described in this invention. Detailed Implementation

[0027] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0028] See Figures 1 to 4 The present invention provides an energy-saving and environmentally friendly method for constructing cast-in-place piles in ultra-deep soft soil layers. The specific implementation process is as follows: a. Site preparation and layout: Level and compact the construction site, and activate the monitoring system to record baseline geological parameters. Purpose: To provide a stable operating platform for the equipment, establish monitoring benchmarks, and provide data support for subsequent adaptive energy recovery.

[0029] b. Casing Installation: A vibratory hammer is used to press the double-layer casing into the soft soil layer in sections. The double-layer casing 1 includes an outer casing 11 and an inner casing 12. The diameter of the outer casing 11 is approximately 50 cm larger than the designed pile diameter, and the diameter of the inner casing 12 is approximately 20 cm larger than the designed pile diameter. The installation depth is determined according to geological conditions. Function: The double-layer casing structure initially stabilizes the borehole opening, prevents soft soil collapse, and provides guidance and protection for subsequent drilling.

[0030] c. Drill Rig Positioning and Drill Bucket Installation: Position the drilling rig and install the drill bucket. The drill bucket 21 is a double-door, double-bottom, high-angle cylindrical bucket with an exhaust port at the top. The height of the drill bucket 21 is 4 meters. Function: To reduce negative pressure.

[0031] d. Hole Drilling and Grouting: Under the adjustable torque conditions of the drilling rig, drilling is carried out in a segmented rotary drilling manner. A slurry system is used to inject slurry into the hole to maintain hole wall stability. When decelerating, the energy recovery device is activated to recover hydraulic energy. The recovered hydraulic energy adaptively provides torque to the hydraulic motor based on the monitored real-time power demand signal. Function: Segmented rotary drilling reduces disturbance to the hole wall; slurry grouting maintains hole wall stability; and the energy recovery system recovers hydraulic energy during deceleration, reducing energy consumption.

[0032] e. Closed-loop mud purification and reinjection: Sand-containing mud from the borehole is pumped to a purification device. After coarse screening and centrifugal separation, the purified mud is reinjected into the borehole for reuse. The purification device is preferably a sand separator. During deceleration, the energy recovery device 4 is activated to recover residual motor braking energy. The recovered residual motor energy adaptively provides electrical power based on the monitored real-time power demand signal. Function: To achieve closed-loop mud circulation, reduce environmental pollution, and further improve energy efficiency through motor braking energy recovery.

[0033] f. Hole Cleaning and Inspection: After drilling reaches the designed depth, a reverse circulation or mud replacement cleaning process is implemented to remove sediment from the bottom of the hole. The hole diameter, depth, mud specific gravity, and sand content are monitored until the design requirements are met. Purpose: To ensure thorough removal of sediment from the bottom of the hole, guarantee the bearing capacity of the pile end, and monitor parameters to ensure the quality of the borehole formation.

[0034] g. Lowering and Positioning of the Reinforcing Cage: Fabricate and lower the reinforcing cage, using a positioning frame to ensure the cage is centered and meets the required protective layer thickness. Purpose: To ensure accurate positioning of the reinforcing cage and guarantee the structural performance of the pile.

[0035] h. Conduit Pouring and Casing Recovery: Underwater continuous concrete pouring is carried out using a conduit. During the pouring process, the conduit is pulled out in sections. When deceleration occurs, the energy recovery device 4 is activated to recover hydraulic energy. The recovered hydraulic energy adaptively provides torque to the hydraulic motor based on the monitored real-time power demand signal. Function: To ensure the quality of continuous concrete pouring, to save materials by simultaneously recovering the casing, and to reduce energy consumption during the pouring process by recovering hydraulic energy.

[0036] See Figures 1 to 4 In the energy-saving and environmentally friendly method for constructing cast-in-place piles in ultra-deep soft soil layers provided by this invention, the drill bucket 21 is a double-door, double-bottomed bucket with an additional vent 211 at the top. Its function is to increase the amount of soil removed per drill bucket operation, improve drilling efficiency, reduce the number of drill lifting operations, and lower energy consumption.

[0037] See Figures 1 to 4 In this invention, an energy-saving and environmentally friendly method for constructing cast-in-place piles in ultra-deep soft soil layers is provided. The diameter of the drill bucket 21 is 2-4 cm smaller than the corresponding pile diameter, and fine-tooth cutting teeth 212 are provided on the outer side of the drill bucket 21. This improves the fluidity of the mud on the outer side of the bucket, reduces sticking, enhances air release, reduces the risk of diameter reduction and hole collapse, and effectively improves construction quality and efficiency.

[0038] See Figures 1 to 4 This invention provides an energy-saving and environmentally friendly method for constructing cast-in-place piles in ultra-deep soft soil layers. The purification device includes a sand pump, a coarse screen, a centrifugal separator, and is equipped with online sensors for mud specific gravity and sand content. The reuse rate of purified mud is not less than 85%. Function: To achieve efficient purification and recycling of mud, significantly reducing mud discharge, and lowering environmental impact and material costs.

[0039] See Figures 1 to 4 The present invention provides an energy-saving and environmentally friendly energy recovery device. The energy recovery device 4 is connected to a monitoring system via a data link. Based on the torque, pump power, and vibratory hammer status output by the monitoring system, the energy recovery device executes an adaptive allocation algorithm in real time to dynamically adjust the hydraulic recovery and electrical energy feedback ratio and supply energy according to priority. Function: To achieve intelligent dynamic management of energy recovery and utilization, optimize energy allocation based on real-time operating conditions, and maximize energy-saving effects.

[0040] See Figures 1 to 4 In the energy-saving and environmentally friendly energy recovery device provided by this invention, the outer casing 11 and the inner casing 12 of the double-layer casing 1 are coaxially arranged, and the inner casing 12 is provided with stiffening ribs 121 and lifting lugs 122. Functions: To ensure the concentricity of the double-layer casing, facilitating construction and recycling; the spacer ring maintains the distance between the casings; the grouting port can be used to grout and reinforce the soil around the hole when needed.

[0041] See Figures 2 to 4 The present invention provides an energy-saving and environmentally friendly energy recovery device 4, comprising a hydraulic accumulator 41, a motor braking module 42, an electrical energy storage unit 43, an inverter module 44, and a control unit 45. The hydraulic accumulator 41 is connected to the hydraulic circuit. The motor braking module 42 is electrically connected to the electrical energy storage unit 43, the inverter module 44, and the control unit 45. The control unit is electrically connected to the hydraulic accumulator. The control unit 45 is electrically connected to the construction monitoring system to collect drilling rig torque and mud pump power conditions in real time and control the start and stop of the hydraulic accumulator or the motor braking module based on an adaptive allocation algorithm. The hydraulic accumulator 41 is connected in parallel with the hydraulic circuit of the drilling rig. When the hydraulic motor deceleration is detected, the hydraulic circuit is automatically switched to store hydraulic energy in the hydraulic accumulator 41. When the deceleration of the drilling rig motor is detected, the electrical energy generated by the motor rotation is processed by the motor braking module 42 and stored in the electrical energy storage unit 43. The electrical energy storage unit 43 supplies power to the drilling rig through the inverter module 44. Function: To construct a complete energy recovery, storage and reuse system, realize the dual recovery and utilization of hydraulic energy and electrical energy, and significantly reduce external energy consumption.

[0042] See Figures 1 to 4 In the energy-saving and environmentally friendly energy recovery device provided by this invention, the energy storage unit 43 is a combined energy storage unit, including a supercapacitor for short-term high-power recovery and a lithium-ion battery for medium- and long-term energy storage, and is equipped with a charge management unit to optimize charging and discharging. Functions: The supercapacitor handles instantaneous high-power recovery and release, the lithium battery provides a continuous energy supply, and the charge management unit protects battery life and optimizes system energy efficiency.

[0043] See Figures 1 to 4 In the energy-saving and environmentally friendly energy recovery device provided by this invention, the hydraulic accumulator 41 is equipped with an adjustable one-way valve 411 and a pressure tank 412 to realize the recovery of hydraulic energy during the drilling deceleration stage. Function: The adjustable one-way valve 411 controls the on / off of the recovery oil circuit, and the pressure tank 412 smoothly absorbs and releases hydraulic shocks, improving recovery efficiency and system stability.

[0044] See Figures 1 to 4In this invention, an energy-saving and environmentally friendly energy recovery device is provided. The control unit 45 is composed of a PLC, which can automatically detect the deceleration phase of the drilling rig and control the energy recovery device 4 to recover hydraulic and electrical energy. Function: The PLC has high reliability and fast response speed, enabling automatic identification of the deceleration phase and precise control of the energy recovery process. During drilling, closed-circuit mud circulation, or guide pipe grouting, when the drilling rig's hydraulic motor, sand pump, drive motor, or other equipment enters a deceleration state, the monitoring system (such as pressure sensors, current sensors, encoders, etc.) detects a decrease in torque, speed, or power in real time. This signal is transmitted to the control unit of the energy recovery device via a data link (such as a CAN bus or industrial Ethernet).

[0045] The core of the control unit 45 is a programmable logic controller (PLC), which has an adaptive allocation algorithm pre-stored within it. This algorithm executes the following logic based on the received real-time signals: Energy recovery decision and type determination: The control unit first determines whether the deceleration source is a hydraulic motor or an electric motor. If it is a hydraulic motor deceleration (such as drill bucket lifting braking or rotary drilling reverse braking), it immediately issues a command to control the electro-hydraulic proportional valve in the hydraulic circuit to switch the high-pressure oil circuit, which was originally discharged through the relief valve, to the hydraulic accumulator circuit, thereby realizing the recovery of hydraulic energy. If it is an electric motor deceleration (such as sand pump stopping or slowing down), it triggers the motor braking module (such as a bidirectional frequency converter) to recover the regenerative braking energy generated by the motor after processing by the inverter module.

[0046] Adaptive adjustment of the energy recovery stage: The recovery process is not a simple "on / off" operation. For example, when recovering hydraulic energy, the opening of the adjustable check valve is dynamically adjusted according to the detected rate of pressure drop in the hydraulic system. If the pressure drops rapidly (indicating intense braking and a large instantaneous energy surge), the opening is increased to accelerate the recovery speed and avoid system pressure shocks; if the pressure drops slowly, the opening is decreased to achieve smooth recovery. The same applies to electrical energy recovery; the recovery current of the braking module is proportionally adjusted according to the decrease curve of the motor speed to achieve smooth braking and maximize energy capture.

[0047] Adaptive allocation and reuse of recovered energy: The recovered energy is not released immediately, but is intelligently allocated based on real-time power demand signals fed back by the monitoring system. The control unit continuously monitors parameters such as the torque required by the drilling rig's hydraulic system and the power required by the mud pump.

[0048] Priority allocation: The algorithm sets the power demand of hydraulic actuators (such as the hydraulic motor that drives the drill pipe) as the highest priority. Once it is detected that the drilling rig needs to increase torque during drilling, the control unit will prioritize instructing the hydraulic accumulator to directly inject its stored hydraulic energy into the main hydraulic circuit in parallel, assisting the main pump in providing torque, thereby reducing the load and energy consumption of the main pump.

[0049] Supply on demand: If there is no immediate need for hydraulic power, the recovered hydraulic energy is temporarily stored in an accumulator for backup. The recovered electrical energy is stored in a combined energy storage unit. When the system detects that the mud pump is starting or the drilling rig motor has a power demand, the inverter module will prioritize using the stored electrical energy to supply power, and any shortfall will be supplemented by the power grid.

[0050] Dynamic adjustment of the recovery / supply ratio: Throughout the process, the adaptive algorithm dynamically calculates the matching degree between the recovered energy and the electricity demand, and adjusts the input ratio of hydraulic recovery and electric energy feedback in real time to ensure that the recovered energy can be used most efficiently and in the most timely manner, thereby realizing the dynamic optimization of the energy consumption of the entire construction system.

[0051] In the closed-loop mud circulation, drilling rig hoisting, and vibratory hammer operation processes of the energy recovery system, the drive motor frequently starts, stops, and changes speed, generating a large amount of recoverable braking energy. The motor braking module (such as a bidirectional frequency converter) detects the motor speed reduction signal in real time and switches the motor to generator mode. The generated three-phase AC power is rectified, inverted, and stored in a combined energy storage unit.

[0052] High power response capability: Supercapacitors can absorb high-power pulse current generated during motor braking within milliseconds, avoiding pollution to the power grid due to current surges, while improving energy recovery efficiency.

[0053] Continuous power supply support: The electrical energy stored in the lithium battery unit is prioritized for power supply under operating conditions such as continuous operation of the mud pump and low-speed drilling of the drilling rig, effectively reducing peak power load and reducing external power consumption by an average of 15% to 25%.

[0054] Thermal management advantages: Compared with traditional resistance braking, regenerative braking generates almost no additional heat, significantly reducing the temperature rise of the electrical control cabinet and improving the system's reliability and continuous operation capability in high-temperature environments.

[0055] Intelligent energy dispatch: The control unit dynamically decides whether to activate energy recovery based on real-time monitoring of motor power demand, energy storage unit status and grid quality, so as to achieve "on-demand use" or "energy storage for standby", thereby improving the overall system energy efficiency.

[0056] Through the above specific implementation methods, the present invention realizes efficient, energy-saving and environmentally friendly cast-in-place pile construction in ultra-deep soft soil layers, effectively solving the industry pain points of unsystematic and unintelligent energy recovery.

[0057] In this invention, all "certain quantity, certain distance" refers to the length necessary to meet design requirements, that is, the length required to meet connection and strength requirements. This length is clear to those skilled in the art and can be set as needed.

Claims

1. A method for constructing cast-in-place piles in ultra-deep soft soil layers using energy-saving and environmentally friendly methods, comprising a double-layer casing, a drilling rig, a mud system, and a regenerative braking device, characterized in that... Follow the steps for construction: a. Site preparation and layout: Level and compact the construction site, and start the monitoring system to record the baseline geological parameters; b. Installation of casing: The double-layer casing is pressed into the soft soil layer in sections using a vibratory hammer. The double-layer casing includes an outer casing and an inner casing. The diameter of the outer casing is approximately 50 cm larger than the designed pile diameter, and the diameter of the inner casing is approximately 20 cm larger than the designed pile diameter. The installation depth is determined according to the geological conditions. c. Drilling rig positioning and drill bucket installation: Position the drilling rig and install the drill bucket, which is a double-door, double-bottom, high-angle cylindrical bucket with an exhaust port at the top; d. Hole drilling and grouting: Drilling is carried out in a segmented rotary drilling manner under the adjustable torque condition of the drilling rig. The grouting system is used to inject grouting mud into the hole to maintain the stability of the hole wall. When deceleration is detected, the energy recovery device is activated to recover hydraulic energy. The hydraulic energy recovered by the energy recovery device adaptively provides the torque of the hydraulic motor according to the monitored real-time power demand signal. e. Closed-circuit mud purification and reinjection: The sand-containing mud in the borehole is pumped to the purification device by a sand pump. After coarse screening and centrifugal separation, the purified mud is reinjected into the borehole for recycling. When deceleration is detected, the energy recovery device is activated to recover the residual braking energy of the motor. The residual motor energy recovered by the energy recovery device adaptively provides electrical energy according to the monitored real-time power demand signal. f. Hole cleaning and inspection: After drilling reaches the designed depth, reverse circulation or mud replacement hole cleaning process is carried out, and sediment at the bottom of the hole is removed. The hole diameter, hole depth, mud specific gravity and sand content are monitored and tested until the design requirements are met. g. Lowering and positioning the reinforcing cage: Fabricate and lower the reinforcing cage, and use a positioning frame to ensure that the reinforcing cage is centered and meets the protective layer thickness requirements; h. Conduit grouting and casing recovery: The conduit is used for continuous underwater concrete grouting. During the grouting process, the conduit is pulled out in sections. When deceleration is detected, the energy recovery device is activated to recover hydraulic energy. The hydraulic energy recovered by the energy recovery device adaptively provides the torque of the hydraulic motor according to the monitored real-time power demand signal.

2. The energy-saving and environmentally friendly construction method for cast-in-place piles in ultra-deep soft soil layers according to claim 1, characterized in that: The drill bucket is a double-door, double-bottom, high-angle sand-scooping drill bucket with exhaust holes at the top, and the drill bucket is raised to 4 meters.

3. The energy-saving and environmentally friendly construction method for cast-in-place piles in ultra-deep soft soil layers according to claim 1, characterized in that: The diameter of the drill bit is 2 to 4 cm smaller than the diameter of the corresponding pile being constructed, and the outside of the drill bit is provided with fine cutting teeth.

4. The energy-saving and environmentally friendly construction method for cast-in-place piles in ultra-deep soft soil layers according to claim 1, characterized in that: The purification device includes a sand pump, a coarse screen, a centrifugal separator, and is equipped with sensors.

5. The energy-saving and environmentally friendly construction method for cast-in-place piles in ultra-deep soft soil layers according to claim 1, characterized in that: The energy recovery device is connected to the monitoring system via a data link. The energy recovery device executes an adaptive allocation algorithm in real time based on the torque, pump power, and vibratory hammer status output by the monitoring system to dynamically adjust the hydraulic recovery and electrical energy feedback ratio and supply energy according to priority.

6. The energy-saving and environmentally friendly construction method for cast-in-place piles in ultra-deep soft soil layers according to claim 1, characterized in that: The outer and inner casings of the double-layer casing are coaxially arranged, and the inner casing is provided with stiffening ribs and lifting lugs.

7. A power recovery device, characterized in that: It includes a hydraulic accumulator, a motor braking module, an electrical energy storage unit, an inverter module, and a control unit. The hydraulic accumulator is connected to a hydraulic circuit, the motor braking module is electrically connected to the electrical energy storage unit, the inverter module, and the control unit, and the control unit is electrically connected to the hydraulic accumulator.

8. The energy recovery device according to claim 7, characterized in that... The energy storage unit is a combined energy storage unit, including a supercapacitor for short-term high-power recovery and a lithium-ion battery for medium- and long-term energy storage, and is equipped with a charge management unit that can optimize charging and discharging.

9. The energy recovery device according to claim 7, characterized in that... The hydraulic accumulator is equipped with a check valve and a pressure tank that enable the recovery of hydraulic energy during the drilling deceleration phase.

10. The energy recovery device according to claim 7, characterized in that... The control unit includes a PLC component, which can automatically detect the deceleration phase of the drilling rig and control the energy recovery device to recover hydraulic and electrical energy.

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