A deep-sea jacket foundation pile foundation underwater pile delivery device and a construction method thereof

Abstract

The application relates to the field of deep-sea offshore wind power construction, and discloses a deep-sea jacket foundation pile foundation underwater pile delivery device and a construction method thereof. The pile delivery device comprises a pile delivery device main body, an air bag and an anchoring mechanism are arranged in the pile delivery device main body from top to bottom; the air bag comprises a bag body, the bottom of the bag body is provided with an inflation air nozzle, the bag body is filled with gas and can be arranged to float up and down; the anchoring mechanism comprises an anchoring ring and an anchoring plate, the anchoring ring is horizontally arranged and fixed at the bottom of the inflation air nozzle, the anchoring plate is arranged in parallel and at intervals below the anchoring ring and is fixed on the inner wall of the pile delivery device main body; the anchoring ring and the anchoring plate are connected through a sling, and the length of the sling is set to satisfy that the distance between the up-floating position of the air bag in the steel cylinder and the anchoring plate is greater than the downward distance of the air bag relative to the steel cylinder when the air bag is impacted by a hydraulic impact hammer; the underwater pile delivery device is used in cooperation with an underwater hydraulic pile hammer to construct, the impact energy transmission efficiency of the hydraulic impact hammer is improved, and the underwater pile delivery device has no obvious deflection deformation before and after construction, so that the construction cost and the construction efficiency are improved.

Description

Technical Field

[0001] This invention relates to the field of offshore wind power construction technology, and in particular to an underwater pile driver for deep-sea jacket foundation piles and its construction method. Background Technology

[0002] With the continuous development of the offshore wind power industry and the increasing installed capacity year by year, the available marine resources in nearshore areas are becoming increasingly scarce. The development of offshore wind power is gradually shifting to the deep sea, and it is expected that the scale of offshore wind power development in the deep sea will reach 120GW~150GW in the future, which is 2 to 3 times the current scale.

[0003] In offshore wind power construction in deep waters, when the water depth exceeds 30m, the foundation structure mainly consists of jacket foundations. Traditional jacket foundation pile construction employs a combination of surface-mounted pile drivers and surface-mounted hydraulic pile hammers. This involves custom-lengthening the surface-mounted pile driver according to the construction water depth, ensuring its bottom aligns with the top of each steel pipe pile, with the top protruding above the water surface. The surface-mounted hydraulic pile hammer then drives the top of the surface-mounted pile driver to complete the pile driving of all steel pipe piles on the jacket foundation. However, as wind power development continues to shift to deeper waters, the current construction water depth has reached 70m. Using the traditional jacket foundation pile construction method, the surface-mounted pile driver faces challenges due to its excessively large slenderness ratio, leading to difficulties in verticality control and susceptibility to deformation. Furthermore, when the surface-mounted pile driver is driven, the extra-long driver is prone to bending vibrations and energy loss under the combined effects of wave currents and hammer impact, resulting in significant energy conduction loss.

[0004] Based on the technical defects of the above-mentioned solutions, another construction method for jacket foundation piles combines an underwater pile driver and an underwater hydraulic pile hammer, aiming to reduce energy loss by decreasing the length of the pile driver. However, in actual construction, the pile driver is located underwater, and its inner cavity is filled with seawater. When the hydraulic pile hammer strikes the pile driver, the seawater inside fluctuates violently due to the impact force. The pipe wall of the pile driver is subjected to impact forces dispersed in different directions by the seawater, resulting in significant energy loss even though the impact energy should be transmitted longitudinally. According to the actual construction results, even within the pipe wall of the pile driver... While methods such as creating drainage holes on the top of the pile driver or adding water channels on the top of the hammer to allow seawater inside to drain directly when impacted, and installing an air compressor at the bottom of the hydraulic impact hammer to supply air for drainage and reduce fluctuations, cannot significantly improve the efficiency of impact energy transfer. Furthermore, creating drainage holes on the pipe wall or water channels on the hammer can damage the structure of the pile driver, leading to stress fractures, reduced lifespan, and increased construction costs. In addition, if the number and size of drainage holes or water channels are inappropriate, there will be problems with low drainage efficiency and the inability to convert seawater fluctuation energy into external energy in a timely manner.

[0005] Based on this, in order to address the aforementioned problems in current offshore wind power construction in deep and far waters, it is urgent to design an underwater pile driver for deep and far water jacket foundation piles and its supporting construction method that can significantly improve the energy transfer efficiency of hydraulic pile hammers. Summary of the Invention

[0006] The purpose of this invention is to provide an underwater pile driver for deep-sea jacket foundation piles that solves the above-mentioned technical problems.

[0007] Another objective of this invention is to develop a method for constructing deep-sea jacket foundation piles using the aforementioned underwater pile driver.

[0008] Therefore, the technical solution of the present invention is as follows:

[0009] A deep-sea jacket foundation underwater pile driver includes a pile driver body, in which an airbag and an anchoring mechanism are arranged from top to bottom in the inner cavity. The airbag includes a cylindrical bladder with an inflation nozzle at the bottom. The bladder is filled with gas and can float up and down in the inner cavity of the pile driver body. The anchoring mechanism includes an anchor ring and an anchor plate. The anchor ring is horizontally arranged and fixedly connected to the bottom of the inflation nozzle. The anchor plate is arranged parallel to the anchor ring below and fixed to the inner wall of the pile driver body. The anchor ring and the anchor plate are connected by a sling, and the length of the sling is such that the distance between the airbag's floating position in the steel cylinder and the anchor plate is greater than the downward distance of the airbag relative to the steel cylinder when it is struck by a hydraulic impact hammer.

[0010] Furthermore, the main body of the pile driver includes a steel cylinder with a pile head at its bottom end; the outer diameter of the steel cylinder is consistent with the outer diameter of the steel pipe pile, and the outer diameter of the pile head is adapted to the inner diameter of the steel pipe pile, so that the main body of the pile driver can be inserted and connected to the steel pipe pile.

[0011] Furthermore, the sealed capsule is composed of an airtight layer, a skeleton layer, and a protective layer, which are sequentially nested from the inside out; wherein, the airtight layer is made of brominated butyl rubber, the skeleton layer is made of polyester cord fabric, and the protective layer is made of neoprene rubber.

[0012] Furthermore, the length of the bladder is 1 / 6 to 1 / 4 of the length of the steel cylinder, and its outer diameter is smaller than the inner diameter of the steel cylinder; the gas filling volume of the bladder is 60% to 75% saturated, so that the maximum volume deformation of the bladder during compression is greater than the outward drainage volume of a conventional pile driver during hydraulic impact hammer construction.

[0013] Furthermore, the gas inside the capsule can be, but is not limited to, air.

[0014] Furthermore, the inflation nozzle includes a fixed base plate, a gas one-way valve, and a protective cap; the fixed base plate is fixedly attached to the opening centered at the bottom of the bladder; the gas one-way valve is vertically inserted into the center of the fixed base plate, with its top end embedded in the bladder, and gas can only flow from an external gas source into the bladder through the gas one-way valve; the protective cap is threadedly connected to the bottom end of the gas one-way valve.

[0015] Furthermore, the fixed substrate is integrally formed by stacking an upper arc-shaped plate and a lower arc-shaped plate, and the diameter of the lower arc-shaped plate is smaller than that of the upper arc-shaped plate; the upper arc-shaped plate is built into the capsule, so that its bottom surface is bonded to the brominated butyl rubber layer in the circumferential direction of the bottom opening of the capsule and vulcanized and fixed; the lower arc-shaped plate extends outward from the bottom opening of the capsule, and its annular outer wall is bonded to the cross-section of the polyester cord fabric layer and the neoprene rubber layer at the bottom opening of the capsule and vulcanized and fixed.

[0016] Furthermore, the anchoring mechanism also includes a buffer protective cover, which is a funnel-shaped cylinder with its open end facing upwards and its bottom end closed; the buffer protective cover is clamped and fixed between the anchoring ring and the inflation nozzle, and is supported by the inner wall of the funnel-shaped cylinder at the stress concentration point of the bladder.

[0017] Furthermore, the anchor plate includes a large-sized annular plate with multiple connecting plates extending outward from its outer annular surface. These connecting plates are evenly distributed in the circumferential direction and fixed to the inner wall of the steel cylinder at their outer ends. The diameter of the central through hole of the large-sized annular plate is larger than the maximum outer diameter of the buffer protective cover. This allows the anchor ring and the buffer protective cover to pass through the central through hole of the large-sized annular plate when they descend to the anchor plate during the process of the airbag being compressed by the hydraulic impact hammer and descending relative to the steel cylinder, thus avoiding hard collisions.

[0018] Furthermore, multiple shackle connection holes are evenly distributed along the circumference on the anchoring ring, and correspondingly, multiple sling holes are evenly distributed along the circumference on the anchoring plate, so that multiple slings are respectively inserted into the multiple sling holes of the anchoring plate, and the two ends of each sling are sleeved on the shackle, and connected to the corresponding shackle connection hole on the anchoring ring through the shackle.

[0019] A construction method for an underwater pile driver for deep-sea jacket foundation piles as described above, comprising the following steps:

[0020] S1. Based on the actual construction situation, customize the main body of the pile driver, airbag and anchoring mechanism, and transport them to the construction vessel for pre-assembly; the airbag is connected to the anchoring mechanism in a de-inflated state, and then inflated on site;

[0021] S2. Crane vessels equipped with hydraulic impact hammers and underwater pile drivers enter the site, anchor at the designated machine position, and steel pipe pile transport vessels and auxiliary positioning frame transport vessels berth at the crane vessels.

[0022] S3. The crane vessel lifts the auxiliary positioning frame on the transport vessel and, after precise positioning, lowers it to the designated underwater position.

[0023] S4. The crane ship lifts the internal expansion pile driver and places it inside the top of the steel pipe pile on the transport ship by rotating the boom.

[0024] S5. Use an internal expansion pile driver to support the inner wall of the steel pipe pile, rotate the boom and lift the underwater pile driver to turn the steel pipe pile over. After turning over, slowly lower the pile guide cylinder aligned with the auxiliary positioning frame until the steel pipe pile sinks into the mud and the pile body remains stable. Repeat this method to complete the insertion and sinking of four steel pipe piles at one machine position.

[0025] S6. Similarly, use an internal expansion pile driver to lift the underwater pile driver and gradually send it underwater;

[0026] S7. Using the guiding equipment and underwater camera on the auxiliary positioning frame, guide the underwater pile driver to insert into the top of the steel pipe pile. At this time, the underwater pile driver is filled with seawater, causing the airbag to float up under the action of buoyancy until the sling is straightened.

[0027] S8. The crane vessel lifts the underwater hydraulic impact hammer, also using the guiding equipment on the auxiliary positioning frame and the underwater camera for guidance, until the underwater hydraulic impact hammer is placed on top of the underwater pile driver.

[0028] S9. Start the underwater hydraulic impact hammer to begin pile driving. During the pile driving process, the airbag is periodically compressed and rebounded with the hammer blows, dynamically maintaining the low-pressure environment inside the underwater pile driver to ensure the efficiency of hammer impact transmission.

[0029] S10. After monitoring the steel pipe piles to the design elevation using the underwater camera and the guiding equipment on the auxiliary positioning frame, lift the underwater pile driver and hydraulic impact hammer, and complete the pile driving construction of the remaining three steel pipe piles in sequence using the same method.

[0030] S11. The underwater hydraulic impact hammer and underwater pile driver are retrieved sequentially to the deck of the crane ship; the crane ship removes the lifting auxiliary positioning frame and moves the ship to the next machine position.

[0031] Compared with existing technologies, this underwater pile driver and construction method for deep-sea jacket foundation piles effectively solves the problems of excessive length, deformation, bending, and severe energy loss associated with existing surface pile drivers. On one hand, it shortens the length of the pile driver and works in conjunction with an underwater hydraulic pile hammer, addressing issues such as excessive slenderness ratio, difficulty in verticality control, and easy deformation of the pile driver. On the other hand, by incorporating an air bladder and anchoring mechanism inside the pile driver, the compressibility of the gas inside the air bladder during the underwater hydraulic impact hammer's strike allows for repeated compression of the air bladder, replacing the traditional method of using an air compressor to expel water from the underwater pile driver. This ensures the effective use of the fully underwater hydraulic pile hammer in conjunction with the pile driver, guaranteeing the efficient operation of the hydraulic system. The invention effectively transmits the impact energy of the pile hammer while ensuring the structural strength of the pile driver remains intact. In summary, by compressing and displacing water using an airbag, the invention avoids complex underwater drainage equipment setups, simplifies the system configuration, and significantly reduces equipment failure rates and maintenance costs. Actual construction verification shows that, compared to traditional surface pile driving methods, in a 70m water depth environment, the hydraulic impact hammer's energy transmission efficiency is improved by 22%, the underwater pile driver exhibits no significant deflection before and after construction, the bending at the point of maximum deformation is reduced by 75%, and the maximum sag is less than 1cm. Comprehensive calculations indicate that this underwater pile driver and its associated construction method achieve an overall reduction in construction costs of 42% and an increase in construction efficiency of approximately 15%. Attached Figure Description

[0032] Figure 1 This is a side view of the underwater pile driver for deep-sea jacket foundation piles of the present invention.

[0033] Figure 2 This is a schematic diagram of the vertical structure of the underwater pile driver for deep-sea jacket foundation piles of the present invention.

[0034] Figure 3 This is a vertical view of the main body of the underwater pile driver in the deep-sea jacket foundation pile driver of the present invention;

[0035] Figure 4 This is a schematic diagram of the vertical structure of the airbag in the underwater pile driver for deep-sea jacket foundation of the present invention.

[0036] Figure 5 This is a partial structural diagram of the connection between the airbag and the anchoring ring in the underwater pile driver for the deep-sea jacket foundation of the present invention.

[0037] Figure 6 This is a bottom view schematic diagram of the airbag and anchoring mechanism in the underwater pile driver for the deep-sea jacket foundation of the present invention.

[0038] Figure 7 This is a schematic diagram of the construction status of the underwater pile driver for deep-sea jacket foundation using the present invention. Detailed Implementation

[0039] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the following embodiments are by no means intended to limit the present invention.

[0040] Taking a 67m deep-sea offshore wind farm project in Zhejiang as an example, this paper provides a detailed description of the underwater pile driver for the deep-sea jacket foundation and its construction method.

[0041] The project initially adopted a traditional construction method, namely a construction scheme using a water-based hydraulic impact hammer equipped with a water-based pile driver. Specifically, during actual construction, the steel pipe pile 4 was first hoisted into the guide tube of the auxiliary positioning frame 7. After the steel pipe pile 4 sank into the mud and stabilized, the water-based pile driver was hoisted and placed on top of the steel pipe pile 4. At this time, the top of the water-based pile driver was exposed above the water surface. The water-based hydraulic impact hammer was then hoisted to the top of the water-based pile driver. After the hammer stabilized, the water-based hydraulic impact hammer was started to carry out the pile driving construction. In this case, the water depth in the construction area is 67m, and the top elevation of the pile is 3m above the mud surface. To ensure that the hydraulic impact hammer does not come into contact with seawater, the main body of the hydraulic pile driver needs to be 70m long with a 3m tip. However, the diameter of the hydraulic pile driver is only 4.5m, which is the same as the diameter of the steel pipe pile 4 of the jacket foundation. The excessively large slenderness ratio causes it to undergo significant deflection deformation during construction due to wave impact and the impact of the hydraulic impact hammer. During impact, the steel pipe pile, the hydraulic pile driver, and the hydraulic impact hammer are not concentric, resulting in eccentric force and damage to the pile driver. Furthermore, according to monitoring during construction, the impact energy of the hydraulic impact hammer decreases by about 40% under the above conditions. In order to meet the impact energy of 2500KJ required by the construction design, the hydraulic impact hammer with the commonly equipped 3500KJ impact energy needs to be replaced with a hydraulic impact hammer with an impact energy of over 4200KJ. Such a high-specification hydraulic impact hammer is not only scarce in the market but also too expensive.

[0042] Based on the above-mentioned construction problems, the project team developed the underwater pile driver and supporting construction method for deep-sea jacket foundation piles of the present invention. The aim is to improve the transmission efficiency of the impact energy of the pile hammer without increasing the construction cost by shortening the length of the pile driver and avoiding the need to open drainage holes on the pile driver or open water channels on the pile driver.

[0043] Based on the project's water depth of 67m, the length of steel pipe pile 4 on the jacket foundation is 89m, and the top elevation of the steel pipe pile 4 is 3m above the mud surface, the main body length of the underwater pile driver for the deep-sea jacket foundation is designed to be 31m, the pile tip is 3m, and the diameter remains unchanged at 4.5m. Compared with traditional surface pile drivers, the main body length is reduced by about 56%, and the cost is reduced. At the same time, the slenderness ratio of the underwater pile driver is also reduced, which can solve the problems of verticality control and deformation.

[0044] See Figure 1 and Figure 2 The underwater pile driver for the deep-sea jacket foundation consists of a pile driver body 1, an airbag 2, and an anchoring mechanism 3.

[0045] See Figure 3 The pile driver body 1 includes a steel cylinder 101, which is a cylindrical elongated tube. A pile head tip 102 is provided at the bottom end of the steel cylinder 101. The outer diameter of the steel cylinder 101 is the same as the outer diameter of the steel pipe pile 4 to ensure that the impact energy of the hydraulic impact hammer can be directly and vertically transmitted to the pipe wall of the steel pipe pile 4, avoiding excessive transmission. The thickness of the steel cylinder 101 is adapted to the length of the pile driver and the impact energy of the hydraulic impact hammer, ensuring that the pile driver meets the strength and fatigue resistance requirements under the high energy and multiple impacts of the hydraulic impact hammer. The pile head tip 102 is a short cylindrical tube with an outer diameter adapted to the inner diameter of the steel pipe pile 4, used to connect the pile driver body 1 to the steel pipe pile 4 via the pile head tip 102, ensuring that the two are coaxially arranged.

[0046] In this embodiment, the steel cylinder 101 is made by horizontally rolling and welding multiple 60mm thick steel plates and then longitudinally butt welding them together, so that the axial length of the steel cylinder 101 is 31m; the pile head tip 102 is forged from high-strength low alloy steel (e.g., Q355D), with an axial length of 3m, and is butt welded to the bottom of the steel cylinder 101 to be fixed as one piece.

[0047] See Figure 4 The airbag 2 includes a cylindrical bladder 202, and an inflation nozzle 201 is provided at the bottom of the bladder 202.

[0048] As a flexible pressure vessel, the bladder 202 is specifically composed of an airtight layer, a skeleton layer, and a protective layer, which are sequentially arranged from the inside out. Specifically, the airtight layer is made of brominated butyl rubber, which utilizes its extremely low permeability to ensure the airtightness of the bladder 202 under high pressure and dynamic load, effectively blocking the penetration of seawater and air. At the same time, it uses elastic deformation to adapt to pressure changes, ensuring that the bladder 202 remains intact during compression-rebound cycles. The skeleton layer is made of polyester cord fabric, which utilizes its good mechanical strength and fatigue resistance to enhance the tensile and impact resistance of the airbag, enabling the airbag to withstand repeated hammering forces from hydraulic impact hammers and preventing excessive deformation or rupture of the airbag. The protective layer is made of neoprene rubber, which utilizes its corrosion resistance and non-degradability to make the bladder 202 durable against corrosion from seawater, microorganisms, etc., preventing degradation, reducing friction damage during construction, enhancing anti-aging ability, and maintaining long-term stable performance in deep-sea construction environments.

[0049] See Figure 4 and Figure 5The inflation nozzle 201 includes a fixed base plate 2011, a gas one-way valve 2012, and a protective cap 2013. The fixed base plate 2011 is fixedly attached to the opening at the center of the bottom of the bladder body 202. The gas one-way valve 2012 is vertically inserted into the center of the fixed base plate 2011, with one end of it built into the bladder body 202, and gas can only flow from an external gas source into the bladder body 202 through the gas one-way valve 2012. The other end of the gas one-way valve 2012 has an external thread on its outer wall. Correspondingly, the protective cap 2013 is a cap body with an internal thread on its inner wall that matches it, so that the protective cap 2013 is detachably threaded to the other end of the gas one-way valve 2012 to close the air inlet port of the gas one-way valve 2012.

[0050] The bladder 202 is filled with air through the air inlet 201. The inflation volume is generally set to 60%~75% saturation, which is 60%~75% of the maximum inflation volume of the bladder 202, based on the water depth of the construction environment and the impact load of the hydraulic impact hammer. This is to utilize the compressibility of gas so that the volume of the bladder 202 has a certain compressible deformation.

[0051] The working principle of the bladder 202 inside the pile driver body 1 is as follows: When the top of the pile driver body 1 is struck by the hydraulic impact hammer, the pile driver body 1, its internal air bladder 2, and the seawater are all simultaneously subjected to downward hammering force. However, since the seawater is a liquid and incompressible, the hammering force it receives will diverge and fluctuate due to the lack of downward force transmission space for the seawater, impacting the inner wall of the pile driver body 1 with forces in different directions, affecting the longitudinal transmission of impact energy by the pile driver. Therefore, in the prior art, the pile driver is designed with drainage holes or water channels to discharge some of the seawater from the inner cavity of the pile driver body 1, and an air compressor is installed at the bottom of the hydraulic impact hammer to supply air for drainage, so as to provide downward force transmission space for the remaining seawater in the inner cavity. Unlike seawater, the airbag 2's bladder 202 is filled with gas, and the gas is compressible. This causes the bladder 202 to compress in volume after being struck by the hydraulic impact hammer, thereby releasing the internal space of the pile driver body 1. This provides downward force transmission space for the seawater in the internal cavity, preventing seawater fluctuations from impacting the inner wall of the pile driver body 1 and affecting the longitudinal transmission of impact energy. Furthermore, in addition to eliminating the need for drilling or grooving modifications to the pile driver, there is no longer a need for an air compressor to drain water from inside the pile driver.

[0052] Before actual construction and use, a feasibility simulation calculation was performed on the scheme of using the bladder 202 compression to replace the traditional air compressor drainage. According to the principle that for every 10m increase in water depth, the water pressure increases by 0.1MPa, the inflation percentage of the bladder 202 affects its equivalent stiffness. Therefore, the inflation pressure of the bladder 202 needs to consider not only maintaining the stability of the bladder volume, but also the compressibility between its volume compression and the impact energy of the hydraulic impact hammer. In combination with the engineering practice of this embodiment, for the most unfavorable stress condition of the bladder 2 at a water depth of 70m, the bladder 2 is subjected to a water pressure of 0.7MPa on one hand, and a hammering effect from the hydraulic impact hammer on the other hand (the hammering frequency is generally 30 times / minute to 60 times / minute, and the impact energy is generally gradually increasing from 200KJ to 3500KJ). It is calculated that when the inflation volume of the bladder 202 is 60% to 75% saturated, its compression ratio is between 20% and 40%. Under the above parameter range, not only can excessive deformation of the bladder 202 be avoided, but its deformation also meets the requirement of greater than the displacement required by the hydraulic impact hammer under the above hammering conditions.

[0053] In this embodiment, the length of the capsule 202 is designed to be 5m, which is 1 / 6 of the length of the steel cylinder 101, to ensure that the capsule 202 has sufficient space to move within the steel cylinder 101; the diameter of the capsule 202 is designed to be 0.1m smaller than the inner diameter of the steel cylinder 101, specifically 4.4m, to ensure that the capsule 202 can be floated up and down within the inner cavity of the steel cylinder 101; based on the water pressure at a water depth of 70m in the construction environment of the underwater pile driver, and the design hammering frequency and impact energy variation range of the hydraulic impact hammer, the air inflation volume inside the capsule 202 is designed to be 70% saturated.

[0054] In this embodiment, the fixing substrate 2011 is made of stainless steel. In terms of structural design, considering that the fixing substrate 2011 is preferably vulcanized and fixed to the airtight layer of the capsule 202, a chemical bond is formed between the brominated butyl rubber layer and the metal fixing substrate 2011, creating a seamless connection interface. This ensures high elasticity and sealing at the connection point to adapt to changes in water pressure and hammering vibrations. Figure 5As shown, the fixed substrate 2011 is integrally formed by stacking an upper arc-shaped plate and a lower arc-shaped plate, and the diameter of the lower arc-shaped plate is smaller than that of the upper arc-shaped plate. Correspondingly, the upper arc-shaped plate is disposed inside the bladder 202, and its bottom surface is attached to and vulcanized with the brominated butyl rubber layer at the bottom opening of the bladder 202. The lower arc-shaped plate extends outward from the bottom opening of the bladder 202, and its annular outer wall is attached to and vulcanized with the cross-section of the polyester cord fabric layer and the neoprene rubber layer at the bottom opening of the bladder 202. A through hole is provided in the center of the fixed substrate 2011, and a gas one-way valve 2012 is inserted and fixed in the through hole of the fixed substrate 2011, with the top end (i.e., the outlet end) of the gas one-way valve 2012 located in the inner cavity of the bladder 202, and its top end (i.e., the inlet end) located outside the bladder 202. In practical applications, when external air is introduced, the internal valve core of the gas check valve 2012 is opened by the air pressure, and the bladder 202 is inflated; when inflation stops, the internal air pressure pushes the valve core back to the valve seat, achieving automatic sealing.

[0055] See Figure 5 and Figure 6 The anchoring mechanism 3 includes a buffer protective cover 301, an anchoring ring 302, a sling 307, and an anchoring plate 308 arranged sequentially from top to bottom.

[0056] The buffer cover 301 is a funnel-shaped cylinder with its open end facing upwards and its bottom end closed. A through hole is provided at the center of the bottom surface of the cylinder, so that the buffer cover 301 is supported on the bottom of the airbag 2 by being sleeved on the outside of the gas one-way valve 2012. The size of the buffer cover 301 is adapted to the size of the airbag 202, so that its inner wall fits snugly against the airbag 202, and the funnel-shaped open end is located above the stress concentration position of the airbag 202, ensuring that the buffer cover 301 surrounds and covers the outside of the stress concentration position of the airbag 202.

[0057] In this embodiment, the bottom of the capsule 202 is an inwardly tapering conical structure, resulting in a geometrical abrupt change in shape at the transition point between the cylindrical and conical sections of the capsule 202, which is also the stress concentration point of the capsule 202. Based on this, the buffer protective cover 301 is designed with a conical shape, covering the outside of the conical structure and supported by the inner wall of the cylinder at the bottom of the conical structure. Its flared opening abuts against the outer wall of the cylindrical section of the capsule 202, and the transition point between it and the conical section is located inside the buffer protective cover 301. Specifically, 301 can be made of hard plastic (such as high-impact polystyrene) in the shape of a trumpet. It not only has the impact resistance and rigidity required as a supporting structure, but also has a certain degree of elasticity. During the compression of the airbag 2 by the hydraulic impact hammer, it can always fit and protect the stress concentration position of the airbag 202 as a protective barrier, offset some of the impact energy, and play a buffering role. This limits the deformation of the airbag 2 at the stress concentration position and the diffusion of stress, preventing the airbag 202 from being damaged due to excessive local deformation.

[0058] The anchoring ring 302 is a small-sized annular plate that is fitted around the outside of the gas check valve 2012 and abuts against the bottom surface of the buffer cover 301. Multiple threaded through holes 303 are evenly distributed circumferentially on the bottom surfaces of the anchoring ring 302 and the buffer cover 301. Correspondingly, multiple threaded blind holes are evenly distributed circumferentially on the bottom surface of the fixing base plate 2011. The anchoring ring 302, the buffer cover 301, and the fixing base plate 2011 are stacked and fixed together from bottom to top using multiple bolts 305 that are correspondingly inserted into the threaded through holes 303 and threaded blind holes. Four shackle connection holes 304 are evenly distributed circumferentially on the annular plate near the outer edge of the anchoring ring 302 for connecting the sling 307.

[0059] Anchor plate 308 is located below anchor ring 302. It includes a large-sized annular plate. Four connecting plates extend outward from the outer annular surface of the large-sized annular plate and are evenly distributed in the circumferential direction. The diameter of the central through hole of the large-sized annular plate is larger than the maximum outer diameter of the buffer cover 301. This allows the anchor ring 302 and the buffer cover 301 to descend relative to the steel cylinder 101 as the airbag 2 is compressed by the hydraulic impact hammer and moves downward. The anchor ring 302 and the buffer cover 301 can then move downward and pass through the central through hole of the large-sized annular plate, preventing hard collisions. The airbag 2 collides with the anchor plate 308, further compressing the volume of the airbag 2. The outer diameter of the anchor plate 308 is adapted to the inner diameter of the steel cylinder 101, allowing it to be fixedly connected to the inner wall of the steel cylinder 101 by welding the ends of the four connecting plates.

[0060] As a preferred technical solution of this embodiment, triangular reinforcing plates 309 are vertically fixed on the outer bottom surfaces of the four connecting plates. Each triangular reinforcing plate 309 is simultaneously welded and fixedly connected to the inner wall of the steel cylinder 101 to increase the structural connection strength between the anchor plate 308 and the steel cylinder 101.

[0061] In this embodiment, the anchoring ring 302 is made of stainless steel plate with a thickness of 20mm to ensure the connection and fixing strength between it and the fixed base plate 2011; the anchoring plate 308 is made of stainless steel plate with a thickness of 20mm to ensure the structural connection strength between it and the steel cylinder 101.

[0062] Each of the four connecting plates of the anchor plate 308 has a sling hole 310 on its inner end plate surface. Four slings 307 are provided, each passing through one of the four sling holes 310 of the anchor plate 308. Each sling 307 has a pre-set lifting ring at both ends. After being folded in half, the slings are fitted onto shackles 306 via the end lifting rings. The shackles 306 then connect to the corresponding shackle connection holes 304 on the anchor ring 302, thus connecting the slings 307 between the anchor ring 302 and the anchor plate 308. The length of the slings 307 is designed such that the distance from the initial floating position of the airbag 2 within the seawater-filled steel cylinder 101 to the anchor plate 308 is greater than the downward distance of the airbag 2 relative to the steel cylinder 101 when struck by a hydraulic impact hammer.

[0063] In this embodiment, the sling 307 is a polyethylene sling with a length of 12m, so that the initial distance between the anchoring ring 302 and the anchoring plate 308 is 6m. In addition to ensuring that there is enough space for the airbag 2 to descend, it also maintains a distance of 4m between the top of the airbag 2 and the top of the steel cylinder 101 to avoid collision and damage with the internal expansion pile driver inserted at the top of the steel cylinder 101.

[0064] In this deep-sea jacket foundation underwater pile driver, the pile driver body 1, airbag 2, and anchoring mechanism 3 work together synergistically. In practical application, as the pile driver is gradually lowered into the sea by hoisting equipment, the pile driver body 1 is gradually filled with seawater. Under the buoyancy of the seawater, the airbag 2 detaches from the anchoring plate 308 and floats up until the hoisting strap 307 is straightened. When the hydraulic pile hammer strikes the top of the pile driver body 1, the pile driver body 1 is driven by the hammer force to move the steel pipe pile 4 connected at the bottom downwards for a certain distance. During this process, the hammer force also acts on the water inside the pile driver body 1, and is then transmitted from the water to the airbag 2, causing the airbag 2 to be compressed and its volume to decrease, leaving space for the seawater to descend within the inner cavity of the pile driver body 1. The underwater pile driver utilizes a force space to achieve energy conversion, avoiding the impact of water waves on the inner wall of the pile driver body 1, effectively transmitting the impact energy of the hydraulic impact hammer, reducing impact energy loss, and suppressing vibration deformation of the underwater pile driver. Since the hammering frequency of the hydraulic impact hammer is approximately 30-60 times / minute, the air bladder 2 can expand and return to its original shape during the interval between adjacent hammerings. This cycle of compression and rebound dynamically maintains a low-pressure environment inside the underwater pile driver, effectively transmitting impact energy to the pile foundation. The underwater pile driver utilizes gas filled in the air bladder 2, which is compressible compared to water. Compared to traditional pile drivers without air bladders that require drainage via an air compressor, the air bladder 2 directly converts energy through compression, avoiding energy loss due to bending vibration and significantly reducing energy loss. The anchor plate 308 is preferably fixed to the middle inner wall of the steel cylinder 101, allowing the air bladder 2 to float in the upper part of the inner cavity of the steel cylinder 101, facilitating rapid energy transfer and conversion.

[0065] See Figure 7 A construction method for a novel underwater pile driver for deep-sea jacket foundation, the specific construction steps of which are as follows:

[0066] S1. Based on the actual construction, the main body 1, airbag 2, and anchoring mechanism 3 of the underwater pile driver are customized and processed, and transported to the construction vessel for pre-assembly. Among them, the airbag 2 is connected to the anchoring mechanism 3 in a de-inflated state, and then inflated on site to about 70% of the saturated state of the airbag 2, and then covered with a protective cap.

[0067] S2. After the crane vessel 5, equipped with a hydraulic impact hammer and an underwater pile driver, enters the site, it anchors and enters the designated position; subsequently, the steel pipe pile transport vessel and the auxiliary positioning frame transport vessel berth the crane vessel.

[0068] S3, the crane ship 5 lifts the auxiliary positioning frame 7 on the transport ship, and after precise positioning, the auxiliary positioning frame 7 is sunk to the designated underwater position;

[0069] S4. The crane ship 5 lifts the internal expansion pile driver 6 and places the internal expansion pile driver 6 inside the top of the steel pipe pile 4 on the transport ship by rotating the boom.

[0070] S5. Use the internal expansion pile driver 6 to support the inner wall of the steel pipe pile 4, rotate the boom and lift the underwater pile driver to turn the steel pipe pile over. After turning over, slowly lower the pile guide tube aligned with the auxiliary positioning frame 7 until the steel pipe pile 4 sinks into the mud and the pile body is stable. Use this method to complete the insertion and sinking of four steel pipe piles 4 at one machine position.

[0071] S6. Similarly, the internal expansion pile driver 6 is used to lift the underwater pile driver. During lifting, the airbag 2 inside the underwater pile driver sinks to the anchor plate 308 under the action of gravity. The inflation nozzle 201, the anchor ring 302 and the buffer protective cover 301 all fall and insert into the central through hole of the anchor plate 308, so that the outer wall of the airbag 2 is in flexible contact with the anchor plate 308, avoiding collision damage at the stress concentration points of the inflation nozzle 201 and the airbag 2.

[0072] S7. Using the guiding equipment and underwater ROV camera on the auxiliary positioning frame 7, guide the underwater pile driver to insert into the top of the steel pipe pile 4. At this time, the underwater pile driver is filled with seawater, causing the airbag 2 to float up under the action of buoyancy until the sling 307 is stretched to its maximum length.

[0073] S8, the crane vessel 5 lifts the underwater hydraulic impact hammer, which is also guided by the guide equipment on the auxiliary positioning frame 7 and the underwater ROV camera, and is then placed on top of the underwater pile driver.

[0074] S9. Start the underwater hydraulic impact hammer to begin pile driving. During the pile driving process, the airbag 2 is periodically compressed and rebounded with the hammer, dynamically maintaining the low-pressure environment inside the underwater pile driver. This allows the airbag 2 to be compressed instead of the conventional underwater hydraulic impact hammer relying on the air compressor to continuously discharge the water inside the underwater pile driver.

[0075] S10. After monitoring the driving of steel pipe pile 4 to the design elevation using the underwater ROV camera and the guiding equipment on the auxiliary positioning frame 7, lift the underwater pile driver and hydraulic impact hammer, and complete the driving of the remaining three steel pipe piles in sequence using the same method.

[0076] S11, the underwater hydraulic impact hammer and the underwater pile driver are retrieved in sequence and placed back on the deck of the crane ship 5; the crane ship 5 removes the lifting auxiliary positioning frame 7 and moves the ship to the next machine position.

[0077] In the later stages of the project's construction, the underwater pile driver and its construction method for the deep-sea jacket foundation piles of this invention were used to complete the pile driving construction of the remaining three jacket foundations. According to on-site construction data, all steel pipe piles 4 were successfully driven to the design elevation, and the penetration depth met the design requirements.

[0078] During the construction project, high-strain detection sensor groups are tightly installed at positions close to the top elevation of the steel pipe pile 4 to collect the axial impact force (F) signal and the particle vibration velocity (v) signal of the pile top section under each effective hammer blow, so as to obtain the monitoring data when the hydraulic impact hammer hammers the steel pipe pile 4 each time, and transmit it to the on-site data industrial controller. The actual energy transmitted to the pile top section (i.e., the sensor installation surface) is automatically calculated through the analysis software supporting the high-strain detection system, and is compared with the traditional offshore pile driving scheme using an ultra-long pile driver in the same wind farm in the early stage.

[0079] The perpendicularity deformation of the pile driver after driving 12 piles with the ultra-long pile driver used in the same wind farm in the early stage was inspected and measured respectively to determine the deflection deformation; the same method was used to determine the deflection deformation after using the underwater pile driver for the deep-sea jacket foundation pile foundation of the present invention. Table 1 below shows the analysis results of the specific data of the differences between the two construction schemes in this project.

[0080] Table 1:

[0081] Difference indicators Traditional construction methods Construction scheme of the present invention range of change Pile driver length 70m 31m shortened by 56% Maximum impact energy required for hydraulic pile hammer 4200KJ 3500KJ Reduce 700KJ Impact on energy transfer efficiency 62% 84% Increased by 22% Bending at the point of maximum deformation of the pile driver 0.8‰ 0.2‰ Reduced by 0.6‰

[0082] As can be seen from Table 1, the underwater pile driver of the present invention reduces the length of the pile driver by about 56% and reduces the manufacturing cost of the pile driver. At the same time, it significantly improves the transmission efficiency of the single blow energy of the hydraulic pile hammer, and reduces the required specifications of the hydraulic pile hammer. It is estimated that under the same working conditions, compared with the traditional construction scheme in the early stage of the project, the construction cost of a single steel pipe pile is reduced by 42% overall.

[0083] On the other hand, due to the reasonable length-diameter ratio of the underwater pile driver of the present invention and no drainage holes or water troughs are opened on it, the structural strength of the underwater pile driver is not easily damaged under the repeated hammer blows of the hydraulic pile hammer. After multiple pile driving operations, no obvious deflection deformation occurs. Compared with the maximum bending degree of 0.8‰ and the maximum sag height of 5.6 cm at the maximum deformation of the ultra-long pile driver used in the early stage of the project, the maximum bending degree at the maximum deformation after using the underwater pile driver of the present invention is 0.2‰, and the maximum sag height is 0.6 cm, and the deflection deformation situation is significantly improved.

[0084] In addition, during the construction process, 1) due to the shortening of the length of the underwater pile driver of the present invention, its weight is also reduced, and the efficiency of the crane turning over and lifting the pile driver is improved; 2) the energy loss of the hydraulic impact hammer is reduced, ensuring the pile driving efficiency, that is, reducing the construction time of a single pile accordingly; 3) the deflection deformation of the underwater pile driver is reduced, and the durability is improved, reducing the possible maintenance time between the steel pipe pile driving operations. Finally, the construction efficiency is improved. It is estimated that the construction efficiency is increased by about 15%.

Claims

1. An underwater pile driver for deep-sea jacket foundation piles, characterized in that, The device includes a pile driver body (1), in which an airbag (2) and an anchoring mechanism (3) are arranged from top to bottom in its inner cavity; the airbag (2) includes a cylindrical bladder (202), with an inflation nozzle (201) at its bottom, the bladder (202) is filled with gas and can float up and down in the inner cavity of the pile driver body (1); the anchoring mechanism (3) includes an anchoring ring (302) and an anchoring plate (308), the anchoring ring (302) is horizontally arranged and fixedly connected to the inflation nozzle (201). 01) At the bottom, the anchor plate (308) is set in parallel at intervals below the anchor ring (302) and fixed on the inner wall of the pile driver body (1); the anchor ring (302) and the anchor plate (308) are connected by a sling (307), and the length of the sling (307) is such that the distance between the airbag (2) floating in the steel cylinder (101) and the anchor plate (308) is greater than the downward distance of the airbag (2) relative to the steel cylinder (101) when it is struck by the hydraulic impact hammer.

2. The underwater pile driver for deep-sea jacket foundation piles according to claim 1, characterized in that, The main body (1) of the pile driver includes a steel cylinder (101) with a pile head tip (102) at its bottom end; the outer diameter of the steel cylinder (101) is consistent with the outer diameter of the steel pipe pile (4), and the outer diameter of the pile head tip (102) is adapted to the inner diameter of the steel pipe pile (4), so that the main body (1) of the pile driver can be inserted and connected to the steel pipe pile (4).

3. The underwater pile driver for deep-sea jacket foundation piles according to claim 1, characterized in that, The capsule (202) is composed of an airtight layer, a skeleton layer and a protective layer arranged sequentially from the inside to the outside; wherein, the airtight layer is a brominated butyl rubber layer, the skeleton layer is a polyester cord fabric layer and the protective layer is a chloroprene rubber layer.

4. The underwater pile driver for deep-sea jacket foundation piles according to claim 1, characterized in that, The length of the capsule (202) is 1 / 6 to 1 / 4 of the length of the steel cylinder (101), and its outer diameter is smaller than the inner diameter of the steel cylinder (101); the gas filling volume of the capsule (202) is 60% to 75% saturated.

5. The underwater pile driver for deep-sea jacket foundation piles according to claim 1, characterized in that, The inflation nozzle (201) includes a fixed base plate (2011), a gas one-way valve (2012), and a protective cap (2013); the fixed base plate (2011) is fixedly attached to the opening in the center of the bottom of the bladder (202); the gas one-way valve (2012) is vertically inserted into the center of the fixed base plate (2011), with its top end embedded in the bladder (202), and gas can only flow from an external gas source into the bladder (202) through the gas one-way valve (2012); the protective cap (2013) is covered and threadedly connected to the bottom end of the gas one-way valve (2012).

6. The underwater pile driver for deep-sea jacket foundation piles according to claim 5, characterized in that, The fixed substrate (2011) is integrally formed by stacking an upper arc-shaped plate and a lower arc-shaped plate, and the diameter of the lower arc-shaped plate is smaller than that of the upper arc-shaped plate. The upper arc-shaped plate is built into the capsule (202), so that its bottom surface is bonded to the brominated butyl rubber layer in the circumferential direction of the bottom opening of the capsule (202) and vulcanized and fixed. The lower arc-shaped plate extends outward from the bottom opening of the capsule (202), and its annular outer wall is bonded to the cross section of the polyester cord fabric layer and the neoprene rubber layer at the bottom opening of the capsule (202) and vulcanized and fixed.

7. The underwater pile driver for deep-sea jacket foundation piles according to claim 1, characterized in that, The anchoring mechanism (3) also includes a buffer protective cover (301), which is a trumpet-shaped cylinder with the open end facing upward and the bottom end closed; the buffer protective cover (301) is clamped and fixed between the anchoring ring (302) and the inflation nozzle (201), and its trumpet-shaped cylinder inner wall supports the stress concentration position of the bladder (202).

8. The underwater pile driver for deep-sea jacket foundation piles according to claim 1, characterized in that, The anchor plate (308) includes a large-sized annular plate with multiple connecting plates extending outward on its outer annular surface. The multiple connecting plates are evenly distributed in the circumferential direction and fixed to the inner wall of the steel cylinder (101) through their outer ends. The diameter of the central through hole of the large-sized annular plate is larger than the maximum outer diameter of the buffer protective cover (301). This allows the airbag (2) to be compressed by the hydraulic impact hammer and descend relative to the steel cylinder (101). When the anchor ring (302) and the buffer protective cover (301) descend to the anchor plate (308), they can pass through the central through hole of the large-sized annular plate to avoid hard collisions.

9. The underwater pile driver for deep-sea jacket foundation piles according to claim 1, characterized in that, Multiple shackle connection holes (304) are evenly distributed along the circumference on the anchor ring (302). Correspondingly, multiple sling holes (310) are evenly distributed along the circumference on the anchor plate (308). Each sling hole (310) corresponds to a shackle connection hole (304), so that multiple slings (307) are respectively inserted into the multiple sling holes (310) of the anchor plate (308). The two ends of each sling (307) are sleeved on the shackle (306) and connected to the corresponding shackle connection hole (304) on the anchor ring (302) through the shackle (306).

10. A construction method for an underwater pile driver for deep-sea jacket foundation piles as described in any one of claims 1 to 9, characterized in that, The steps are as follows: S1. Based on the actual construction situation, customize the main body of the pile driver, airbag and anchoring mechanism, and transport them to the construction vessel for pre-assembly; after the airbag is connected to the anchoring mechanism in a deflated state, it is inflated on site; S2. Crane vessels equipped with hydraulic impact hammers and underwater pile drivers enter the site, anchor at the designated machine position, and steel pipe pile transport vessels and auxiliary positioning frame transport vessels berth at the crane vessels. S3. The crane vessel lifts the auxiliary positioning frame on the transport vessel and, after precise positioning, lowers it to the designated underwater position. S4. The crane ship lifts the internal expansion pile driver and places it inside the top of the steel pipe pile on the transport ship by rotating the boom. S5. Use an internal expansion pile driver to support the inner wall of the steel pipe pile, rotate the boom and lift the underwater pile driver to turn the steel pipe pile over. After turning over, slowly lower the pile guide cylinder aligned with the auxiliary positioning frame until the steel pipe pile sinks into the mud and the pile body remains stable. Repeat this method to complete the insertion and sinking of four steel pipe piles at one machine position. S6. Similarly, use an internal expansion pile driver to lift the underwater pile driver and gradually send it underwater; S7. Using the guiding equipment and underwater camera on the auxiliary positioning frame, guide the underwater pile driver to insert into the top of the steel pipe pile. At this time, the underwater pile driver is filled with seawater, causing the airbag to float up under the action of buoyancy until the sling is straightened. S8. The crane vessel lifts the underwater hydraulic impact hammer, also using the guidance equipment on the auxiliary positioning frame and the underwater camera, until the underwater hydraulic impact hammer is placed on top of the underwater pile driver. S9. Start the underwater hydraulic impact hammer to begin pile driving. During the pile driving process, the airbag is periodically compressed and rebounded with the hammer blows, dynamically maintaining the low-pressure environment inside the underwater pile driver to ensure the efficiency of hammer impact transmission. S10. After monitoring the steel pipe piles to the design elevation using the underwater camera and the guiding equipment on the auxiliary positioning frame, lift the underwater pile driver and hydraulic impact hammer, and complete the pile driving construction of the remaining three steel pipe piles in sequence using the same method. S11. The underwater hydraulic impact hammer and underwater pile driver are retrieved sequentially to the deck of the crane ship; the crane ship removes the lifting auxiliary positioning frame and moves the ship to the next machine position.

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