Pile group composite mooring anchoring device for offshore floating structure and construction method

Abstract

The invention discloses a pile group composite mooring and anchoring device for an offshore floating structure and a construction method.The pile group composite mooring and anchoring device comprises a base, a plurality of foundation piles and a plurality of sleeves vertically connected to the base, the base is used for being immersed on a seabed, and the foundation piles correspond to the sleeves one to one; the foundation pile penetrates through the casing pipe along the axis of the corresponding casing pipe and is inserted into a seabed, the foundation pile is fixedly connected with the corresponding casing pipe, the base is provided with a rotatable traction mechanism, and the rotatable traction mechanism is used for being connected with an offshore floating structure. The anchoring device has the effect of improving the offshore construction convenience, applicability and stability of the anchoring device.

Description

Technical Field

[0001] The present application relates to the field of floating mooring and anchoring construction, and in particular to a pile group composite mooring and anchoring device for an offshore floating structure and a construction method thereof. Background Art

[0002] As an offshore floating structure, floating wind turbines need to be constrained in position and movement by a mooring and anchoring system. As a tall structure at sea, floating wind turbines are more than 100 meters above the sea surface, and their overall weight is close to 10,000 tons. When operating at sea, a reliable mooring and anchoring system is needed to ensure stability and safety.

[0003] In the relevant technology, the mooring of offshore floating bodies needs to be connected to the seabed through anchoring devices. According to the form and mechanical characteristics of the anchoring devices, they can be roughly divided into grip anchors, gravity anchors, pile anchors and suction anchors. Among them, grip anchors (drag embedded anchors) are the most widely used anchoring structures. They are partially or completely embedded in the seabed and mainly rely on the friction between the front structure of the anchor and the soil to resist external forces. They can withstand large horizontal forces, but their vertical force bearing capacity is not strong. Gravity anchors mainly resist the horizontal tension of the anchor chain through the friction between the ballast and the seabed surface, and resist the vertical tension of the anchor chain through the ballast weight. As the requirements for the vertical tension level of the anchor chain increase, the designed gravity anchors require a larger ballast volume, and the horizontal tension is usually difficult to balance simply through the friction between the ballast and the seabed. Its performance is closely related to the seabed, which limits its scope of use; then, the pile anchor is driven into the seabed, and the horizontal tension and vertical tension of the anchor chain are provided by the force between the pile foundation and the soil. In order to ensure that the pile foundation has sufficient structural strength, the diameter of the steel pipe pile reaches 4 meters and the weight exceeds 400 tons. This requires high performance of offshore lifting ships, and the marine engineering is difficult. It is deep in the mud, and has high requirements for complex geological conditions and is difficult to operate; in addition, the suction anchor is a hollow steel cylinder structure. The pressure difference between the inside and outside of the steel cylinder is caused by the artificial pump installed on the top of the steel cylinder. When the pressure inside the steel cylinder is less than that outside the steel cylinder, the steel cylinder is immediately sucked into the seabed, and then the pump is withdrawn. It can withstand the horizontal tension and vertical tension of the mooring line, but the suction anchor foundation is suitable for soft clay geology. For deep seas such as exposed bedrock and extremely thin soil layers, this foundation form is not suitable. In view of the shortcomings of the four traditional anchoring methods, it is necessary to provide an anchoring foundation that is easy to construct at sea and has strong applicability and high stability for use in offshore floating structures. Summary of the invention

[0004] In order to improve the convenience, applicability and stability of offshore construction of an anchoring device, the present application provides a pile group composite mooring anchoring device for an offshore floating structure and a construction method.

[0005] The present application provides a pile group composite mooring anchoring device and construction method for an offshore floating structure, which adopts the following technical solutions: A pile group composite mooring anchoring device for an offshore floating structure comprises a base, a plurality of foundation piles, and a plurality of casings vertically connected to the base. The base is used to be sunk to the seabed, a plurality of the foundation piles correspond to a plurality of casings one by one, the foundation piles penetrate the casings along the axes of the corresponding casings and are inserted onto the seabed, and the foundation piles are fixedly connected to the corresponding casings.

[0006] By adopting the above technical scheme, the base is used as the main structure of the mooring and anchoring system, and a number of vertically arranged casings are used as connecting components between the base and the foundation piles. By passing a plurality of foundation piles through the casings along the axes of the corresponding casings and inserting them onto the seabed, the base is secured to the plurality of foundation piles through the casings, thereby forming a mooring and anchoring system of a pile group composite, which replaces large-diameter steel pipe piles, thereby improving the stability of the mooring and anchoring system, and can also be applied to sea areas with soft clay geology, exposed bedrock or thin soil layers, thereby improving the applicability of the mooring and anchoring system.

[0007] Preferably, the base is provided with a rotatable traction mechanism, and the rotatable traction mechanism is used to connect with the offshore floating structure.

[0008] By adopting the above technical solution, the anchoring system is divided into foundation piles, a pedestal and a rotatable traction mechanism component for assembly, and the mooring anchoring system is constructed in a step-by-step assembly manner, which reduces the dependence on large ship cranes, simplifies the hoisting and transportation steps of the mooring anchoring system, and is conducive to improving the convenience of offshore construction of the anchoring device.

[0009] Preferably, the base is a frame structure, and an anti-sinking plate is horizontally arranged at the bottom of the base.

[0010] By adopting the above technical solution and using a frame structure as the base, the material consumption can be reduced while satisfying the structural strength of the base itself, and the stable sinking of the base can be facilitated. The anti-sinking plate setting can help reduce the probability of the base sinking into the riverbed of soft clay geology, so as to maintain the stability of the base and facilitate the foundation piles to pass through the casing smoothly and be inserted into the riverbed.

[0011] Preferably, a bell mouth is provided at the top of the sleeve, and the bell mouth widens toward the periphery.

[0012] By adopting the above technical solution, the bell mouth widens the opening at the top of the casing, making it easier for the foundation pile to be inserted into the casing, which is beneficial to improving the construction efficiency of the anchoring device.

[0013] A pile group composite mooring anchoring construction method for an offshore floating structure, using a pile group composite mooring anchoring device, comprises the following steps: S1: Construction preparation: prefabricate the foundation and foundation piles and transport them to the construction sea area by transport ship; S2: Foundation hoisting: lift the foundation on the transport ship and lower it to the riverbed surface in the construction sea area; S3: Foundation pile hoisting: hoist the foundation pile on the transport ship and gradually turn it over to an upright state; S4: inserting foundation piles: move the foundation piles to the top of the base and align them with the top opening of the corresponding casing, then lower the foundation piles vertically, pass the lower end of the foundation piles through the corresponding casing and insert them into the riverbed, and repeat the steps of inserting foundation piles until several foundation piles are inserted; S5: foundation pile sinking: hammer the tops of several foundation piles in sequence to make them all firmly fixed in the riverbed, and then connect and fix the foundation piles and casings to make the foundation piles, base and casings form a pile group composite mooring anchoring system; S6: The rotatable traction mechanism is connected to the offshore floating structure.

[0014] By adopting the above technical scheme, the base is first stably sunk to the riverbed surface, and then the foundation pile lowering steps are carried out in sequence and stably until multiple foundation piles are inserted and piled to stabilize the anchor foundation. The base and casing are assembled to form a mooring anchoring system with a pile group composite. The mooring anchoring system is constructed in a step-by-step assembly manner, which reduces the dependence on large ship cranes and can simplify the hoisting and transportation steps of the mooring anchoring system, which is conducive to improving the convenience of offshore construction of the anchoring device.

[0015] Preferably, in the foundation pile sinking step of S5, the pile driving energy is gradually increased from small to large during pile sinking, and the pile driving energy is increased after the foundation pile is sunk to a certain depth and the pile body of the foundation pile is stable.

[0016] By adopting the above technical solution, the stability of the foundation piles is poor in the initial stage of pile sinking, and the piling energy is gradually increased in a slowly increasing manner, which is beneficial to reducing the situation where the foundation piles appear to deviate at large angles.

[0017] Preferably, a self-sealing packer is provided at the bottom of the casing. After the foundation pile sinking step of S5 is completed, an annular space is formed by the inner wall of the casing and the outer wall of the foundation pile, and the self-sealing packer seals the bottom of the annular space; in the connection step of the foundation pile and the casing of S5, grouting is poured into the annular space to connect the foundation pile and the casing.

[0018] By adopting the above technical scheme, the bottom of the annular space formed by the inner wall of the casing and the outer wall of the foundation pile is sealed with a self-sealing packer to facilitate grouting connection between the inner wall of the casing and the foundation pile. The self-sealing packer relies on the interference and pressure difference between the outer diameter of the packer and the inner diameter of the casing to achieve sealing. The setting of the self-sealing packer is conducive to reducing the outflow of mud.

[0019] Preferably, a plurality of guide plates are distributed around the inner wall of the casing, and the length direction of the guide plates is consistent with the length direction of the casing. In the foundation pile inserting step of S4, the foundation piles are inserted into the seabed under the guidance of the guide plates.

[0020] By adopting the above technical solution, a guide plate is added inside the casing to ensure that the space between the casing and the foundation pile is uniform after the foundation pile insertion step is completed, which is beneficial to improving the verticality of the foundation pile and the subsequent grouting connection construction of the annular space.

[0021] Preferably, when the seabed surface of the construction area is a rock layer, a drilling platform located above the base is built after completing the base hoisting step of S2, and the top surface of the drilling platform is higher than the sea level of the construction area. Then, the rock layer of the seabed is drilled from the drilling platform, and the drilling direction is consistent with the axis of the casing.

[0022] By adopting the above technical solution, when the seabed is a rock layer, a drilling platform is built and used as a construction platform for drilling holes in the rock layer, and holes are drilled toward the seabed surface along the axis direction of the casing to facilitate inserting the foundation piles into the seabed.

[0023] In summary, the present application includes at least one of the following beneficial technical effects: 1. By using the base as the main structure of the mooring and anchoring system, and using a number of vertically arranged casings as the connecting components between the base and the foundation piles, a plurality of foundation piles are inserted through the casings along the axis of the corresponding casings and inserted onto the seabed, thereby forming a mooring and anchoring system with a pile group composite, which replaces the large-diameter steel pipe piles, improves the stability of the mooring and anchoring system, and can also be applied to sea areas with soft clay geology, exposed bedrock or thin soil layers, improves the applicability of the mooring and anchoring system, reduces the dependence on large ship cranes, simplifies the hoisting and transportation steps of the mooring and anchoring system, and is conducive to improving the convenience of offshore construction of the anchoring device; 2. By using a self-sealing packer to seal the bottom of the annular space formed by the inner wall of the casing and the outer wall of the foundation pile, it is convenient to make a grouting connection between the inner wall of the casing and the foundation pile, which is helpful to reduce the outflow of mud; 3. When the seabed is a rock layer, a drilling platform is built and used as a construction platform for drilling holes in the rock layer, and holes are drilled toward the seabed surface along the axis of the casing to facilitate inserting the foundation piles into the seabed. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the three-dimensional structure of a pile group composite mooring anchoring device for an offshore floating structure according to an embodiment of the present application.

[0025] Figure 2 It is a top view of a pile group composite mooring anchoring device for an offshore floating structure according to an embodiment of the present application.

[0026] Figure 3 yes Figure 2 A magnified schematic diagram of center A.

[0027] Figure 4 It is a front view of a pile group composite mooring anchoring device for an offshore floating structure according to an embodiment of the present application.

[0028] Figure 5 It is a schematic diagram of the state of a crane vessel and a transport vessel in position in a method for constructing a pile group composite mooring and anchoring for an offshore floating structure according to an embodiment of the present application.

[0029] Figure 6 It is a schematic diagram of the state when a crane vessel lifts a base in a pile group composite mooring and anchoring construction method for an offshore floating structure in an embodiment of the present application.

[0030] Figure 7 It is a schematic diagram of the state when a crane vessel lowers a base in a pile group composite mooring and anchoring construction method for an offshore floating structure according to an embodiment of the present application.

[0031] Figure 8 It is a schematic diagram of the state of foundation piles during construction in a method for constructing a group of pile composite mooring and anchoring for an offshore floating structure according to an embodiment of the present application.

[0032] Fig. 9 It is a schematic diagram of the construction state when the seabed surface of the construction sea area is a rock layer in a pile group composite mooring and anchoring construction method for an offshore floating structure in an embodiment of the present application.

[0033] Explanation of the accompanying reference numerals: 1. base; 2. casing; 3. foundation pile; 4. bell mouth; 5. self-sealing packer; 6. anti-sinking plate; 61. through hole; 7. lifting ear; 8. rotatable traction mechanism; 9. guide plate; 10. annular space; 11. sacrificial anode protection device; 12. crane vessel; 13. transport ship; 14. drilling platform. DETAILED DESCRIPTION

[0034] The following is combined with Figure 1-4 This application is described in further detail.

[0035] The present application embodiment discloses a pile group composite mooring anchoring device for an offshore floating structure, referring to Figure 1, including a base 1 and a plurality of foundation piles 3, wherein the base 1 is vertically provided with a plurality of casings 2. The plurality of foundation piles 3 correspond to the plurality of casings 2 one by one. The foundation piles 3 penetrate the casings 2 along the axis of the corresponding casings 2 and are inserted into the seabed, and the foundation piles 3 are fixedly connected to the corresponding casings 2, thereby forming a stable pile group composite mooring anchoring device.

[0036] Reference Figure 1 and Figure 2 In this embodiment, the base 1 is a frame-type component formed by welding a plurality of steel pipes, and a sacrificial anode protection device 11 is provided on the steel pipe of the base 1 as an anti-corrosion protection measure (refer to Figure 4 ). The base 1 is fixed with lifting ears 7 around it, and the lifting ears 7 are used to connect with the hooks of the crane ship 12, so that the base 1 can be sunk to the seabed by lifting. The base 1 is used as the main structure of the mooring anchoring device, which can reduce the amount of materials on the basis of meeting the structural strength of the base 1 itself. The bottom of the base 1 is horizontally fixed with an anti-sinking plate 6, and the anti-sinking plate 6 is evenly distributed with a number of through holes 61, which is convenient for the stable sinking of the base 1 and helps to reduce the probability of the base 1 sinking into the riverbed of soft clay geology, so as to maintain the stability of the base 1 and facilitate the foundation pile 3 to pass through the casing 2 and be inserted into the riverbed smoothly.

[0037] Reference Figure 1 and Figure 2 In this embodiment, there are four casings 2, which are placed at the four corners of the base 1. A bell mouth 4 is fixed at the top of the casing 2, and the bell mouth 4 expands outwards to facilitate the insertion of the foundation pile 3 into the casing 2. A self-sealing packer 5 is installed at the bottom of the casing 2, and the self-sealing packer 5 achieves sealing by the interference and pressure difference between the outer diameter of the packer and the inner diameter of the casing 2.

[0038] Reference Figures 1 to 3 When the foundation pile 3 is inserted into the casing 2, the inner wall of the casing 2 and the outer wall of the foundation pile 3 form an annular space 10, and the self-sealing packer 5 seals the bottom of the annular space 10 to facilitate the connection of the casing 2 and the foundation pile 3 by grouting.

[0039] Considering the uncertainty of each floating structure, sea area geology, and ocean hydrology, the foundation pile 3 adopts an open variable wall thickness steel pipe pile with a diameter of φ ranging from 1.2m to 2.0m, with a wall thickness of 30mm to 50mm, and a pile length of about 15m to 20m. The top of the foundation pile 3 is 21m higher than the casing of the integral base 1, and the pile body is 10m to 15m deep in the mud (depending on the seabed type). The foundation pile 3 is processed and manufactured on land, and the offshore construction adopts a crane ship 12 and a hydraulic hammer to sink the pile in water.

[0040] In this embodiment, a plurality of guide plates 9 are distributed around the inner wall of the casing 2, and the length direction of the guide plates 9 is consistent with the length direction of the casing 2 to ensure that when the foundation pile 3 is inserted into the casing 2, the space between the casing 2 and the foundation pile 3 is uniform, which is beneficial to improving the verticality of the foundation pile 3 and the subsequent grouting connection construction of the annular space 10.

[0041] Reference Figure 1 and Figure 4 In this embodiment, the base 1 has a rotatable traction mechanism 8, which includes a rotary bearing installed at the base 1 and a connecting steel member connected to the rotary bearing. In this embodiment, the rotary bearing can be installed at any position such as the bottom, top or side of the base according to actual needs. The connecting steel member is used to connect with the anchor cable of the offshore floating structure (not shown in the figure) to facilitate mooring connection in different directions. Multiple rotary traction mechanisms can be added to facilitate the connection of multiple mooring points.

[0042] The present application also discloses a method for constructing a pile group composite mooring anchoring for an offshore floating structure, using a pile group composite mooring anchoring device, comprising the following steps: S1: Construction preparation: refer to Figure 5 and Figure 6 , prefabricated foundation 1 and foundation piles 3 on land. Then the crane ship 12 first enters the construction sea area and anchors and positions, and is towed by a tugboat to the vicinity of the anchor device installation position with the help of the GPS navigation and positioning system, and anchors and stays in position. The crane ship 12 is about 100m away from the designed position of the anchor device. The ship positions and throws 8 positioning anchors, each with a 12t large grip anchor, and the anchor length is about 500m. Then the foundation 1 and multiple foundation piles 3 are transported to the construction sea area by the transport ship 13. The transport ship 13 is close to the crane ship 12, and the transport ship 13 throws two anchors at the bow and stern, a total of 4 anchors, with an anchor length of 300m. The overall base position above the transport ship 13 is adjusted to coincide with the designed installation position of the anchor device by twisting the anchor.

[0043] S2: Hoisting of base 1: The crane vessel 12 moves the position by winching the anchor so that the main hook reaches above the base 1. Then the main hook drops to the lifting lug 7 at the top of the base 1 and performs the hooking operation. After the hooking is completed, the base is untied. Positioning equipment is placed on the top of the base 1, and the positioning personnel debug the equipment. After the untying is completed, the crane vessel 12 lifts the main hook, and the load is reported every time the main hook load increases by 50t. When the load increases by 50%, it stops and observes for 3 minutes. After confirming that there is no problem, the load continues to increase. When the load increases by 75%, it stops again and observes for 3 minutes. Stop lifting after the overall base leaves the barge deck by 50cm, observe for 5 minutes, and confirm that there is no abnormal sound or problem before lifting. During this period, the positioning system is observed in real time to ensure the reliability of the positioning system. Once an abnormality is found, the lifting is stopped, and maintenance is carried out in time or the backup system is activated.

[0044] Then the crane vessel 12 lifts the base 1 on the transport ship 13. After the entire base 1 is lifted to a suitable height, the transport ship 13 is moved horizontally out of the placement position. The crane vessel 12 is controlled by the deck crew according to the instructions of the positioning system, and the crane vessel 12 is adjusted to the installation position, and the base 1 is started to be lowered, and the position and orientation are observed in real time during the lowering process.

[0045] When the bottom of the integral base 1 is 1m away from the seabed, the hook is stopped. After the integral base 1 is stationary, the surveyor immediately calculates the deviation value based on the RTK feedback data on it and gives instructions for moving direction and distance. The crane operator adjusts accordingly until the installation position accuracy meets the requirements.

[0046] Reference Figure 7 After the overall base 1 is confirmed to be in the correct position, it is finally lowered to the riverbed surface in the construction sea area.

[0047] Check the position and azimuth of the base 1 again. If they meet the design requirements, remove the slings and prepare for the subsequent pile driving operation.

[0048] S3: Foundation pile 3 hoisting: refer to Figure 8 After the overall foundation 1 is hoisted, the ship position is readjusted, and the hook of the crane ship 12 is moved horizontally to the foundation pile 3 at the transport ship 13.

[0049] The present application uses two hooks to lift the foundation pile 3, one of which is connected to the top of the foundation pile 3 by an internal lifting pile lifter. The other hook is connected to the bottom of the foundation pile 3 by a turning clamp. The double main hooks of the crane ship 12 start to lift synchronously. When the foundation pile is completely about 0.5m away from the deck of the transport ship 13, the lifting is suspended to check the stress of the wire rope. If no abnormality is found, the lifting is continued. When the foundation pile 3 is lifted horizontally to a distance of 2 to 3m from the deck of the transport ship 13, the pile transport ship moves sideways out of the construction area for turning the foundation pile 3 upright. The main hook of the crane ship 12 connected to the top of the foundation pile 3 is slowly lifted, and the foundation pile 3 is slowly turned over by the coordinated operation of the double main hooks, and gradually turned over to an upright state.

[0050] S4: Inserting foundation pile 3: The crane ship 12 adjusts the ship position and finally moves the foundation pile 3 to the top of the integral base 1. Then, the turning clamp is removed and the bottom of the foundation pile 3 is inserted to the top of the casing 2. Then, the foundation pile 3 is lowered according to the guidance of the positioning device to insert the foundation pile 3. After the pile sinks and hits the mud surface, it first sinks by its own weight, and the hook head maintains the lifting force to prevent the pile body from sinking and impacting the base 1 due to the complete loosening of the hook.

[0051] The lower end of the foundation pile 3 passes through the corresponding casing 2 under its own gravity and is inserted into the riverbed. After the foundation pile 3 is inserted and self-sunk, the internal lifting pile lifter at the top of the foundation pile 3 is removed from the pile, and each ship readjusts its position and repeats the above actions to erect the second foundation pile 3 and insert it to the diagonal position of the first foundation pile 3 until four foundation piles 3 are inserted.

[0052] S5: Pile sinking of foundation piles 3: hammer the tops of several foundation piles 3 in sequence to make them all firmly fixed in the riverbed. Hydraulic pile hammers are used for steel pipe pile sinking. When the hydraulic pile hammer starts sinking piles, the striking energy increases from small to large. After the foundation piles 3 are sunk to a certain depth and the pile body of the foundation piles 3 is stable, the piling energy is appropriately increased. When encountering soft soil layers, the striking energy is appropriately reduced; when encountering harder soil layers, pile driving is carried out according to the rated power. In principle, one pile should be driven in at a time, and the hammer should not be stopped in the middle.

[0053] Since the foundation pile 3 is an underwater pile, which involves underwater piling, the pile driving operation is completed with the help of a pile driver during the pile sinking. In order to prevent the pile hammer from entering the water too deeply and taking into account factors such as tidal range, the pile driver should be higher than the water surface after installation. The lower section of the pile driver is conical and its diameter is larger than the diameter of the foundation pile 3, so that it can be inserted into the top of the foundation pile 3 and fixed. The upper diameter design should meet the requirements of the pile driver's hammer sleeve. The crane ship 12 lifts the pile driver and lifts it to the top of the foundation pile 3 to complete the docking, and then continues to drive the foundation pile 3 until the foundation pile 3 is sunk into place.

[0054] After the piles are sunk, an annular space 10 is formed between the casing 2 of the integral foundation 1 and the foundation pile 3. Then, a main grouting pipe and a spare grouting pipe are arranged on the casing 2, and grouting is performed into the annular space 10 through the grouting pipe to grout the foundation pile 3 and the casing 2 so as to connect them by grouting, so that the foundation pile 3, the foundation 1 and the casing 2 constitute a mooring anchoring system of a pile group composite.

[0055] S6: The rotatable traction mechanism 8 is connected to the offshore floating structure.

[0056] Reference Fig. 9 It should be emphasized that, in other embodiments, when the seabed surface of the construction sea area is a rock layer, a drilling platform 14 located above the base 1 is built after completing the base 1 hoisting step of S2.

[0057] The drilling platform 14 is transported to the construction sea area by the transport ship 13. The crane ship 12 uses a 4-point hoist to install the drilling platform 14. During the hoisting, the crane ship 12 slowly releases the cable to allow the drilling platform 14 to enter the water. When the bottom of the drilling platform 14 is about 11m away from the base, the cable release is stopped. When the platform is stable, the crane ship 12 slowly winds the cable for precise positioning, so that the center of the drilling platform 14 coincides with the center of the base 1 (within an error of 0.5m), and then the cable release continues to sink the drilling platform 14. The installation and lifting process of the drilling platform 14 ensures neat and parallel lifting, and the lifting height of the four corners of the platform should be observed throughout the lifting process.

[0058] The drilling platform 14 is located above the sea level of the construction area, and then the rock layer of the seabed is drilled from the drilling platform 14, and the drilling direction is consistent with the axis of the casing 2. The drilling construction is carried out using an air lift reverse circulation drilling rig. According to the on-site seabed geological exploration report, on-site rock sample data and drilling slag sampling analysis during pile extraction: (1) If the drill bit sampled from the pile borehole is blue-grey block rock with well-developed calcite veins and a reticular pattern, the drilling tool will drill to the bottom elevation of the hole in one go to meet the requirements of the designed pile bottom.

[0059] (2) If the drilling slag sampled from the pile borehole is light grey, the rock mass is broken, mainly in the form of gravel, and the rock blocks are easily broken by hand, the drilling-driving-drilling-driving construction process is adopted. The first drilling is carried out to 1 / 2 of the bottom elevation of the pile hole, and then the pile is driven once; the second drilling is carried out to the bottom elevation of the pile hole, and then the pile is driven twice, until the drilling reaches the designed pile bottom elevation.

[0060] The drill bit edge is constantly worn during the construction process, and the diameter wear should not exceed 1.5cm. Before each shift, check the drill bit diameter and weld it in time. Do not repair it in the middle to avoid drilling. Prepare spare drill bits for rotation and repair.

[0061] The drill cutter drills to the hole bottom elevation and can smoothly drill to the pile bottom so as to insert the foundation pile 3 into the seabed with the surface being the rock layer. After the drilling construction below the four casings 2 is completed, the subsequent step S2 can be performed.

[0062] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A pile group composite mooring anchoring device for an offshore floating structure, characterized in that: The invention comprises a base (1) and a plurality of foundation piles (3), wherein the base (1) is vertically connected to a plurality of casings (2), the base (1) is used for being sunk to the seabed, the plurality of foundation piles (3) correspond to the plurality of casings (2) one by one, the foundation piles (3) penetrate the casings (2) along the axis of the corresponding casings (2) and are inserted into the seabed, and the foundation piles (3) are fixedly connected to the corresponding casings (2).

2. A pile group composite mooring anchoring device for an offshore floating structure, characterized in that: The base (1) is provided with a rotatable traction mechanism (8), and the rotatable traction mechanism (8) is used to be connected to an offshore floating structure.

3. The pile group composite mooring anchoring device for offshore floating structures according to claim 1, characterized in that: The base (1) is a frame structure.

4. The pile group composite mooring anchoring device for offshore floating structures according to claim 3 is characterized in that: An anti-sinking plate (6) is horizontally arranged at the bottom of the base (1).

5. The pile group composite mooring anchoring device for offshore floating structures according to claim 1, characterized in that: The top of the sleeve (2) is provided with a bell mouth (4), and the bell mouth (4) widens toward the periphery.

6. A method for constructing a pile group composite mooring anchoring for an offshore floating structure, using the pile group composite mooring anchoring device according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1: Construction preparation: prefabricate the foundation (1) and foundation piles (3) and transport them to the construction sea area by transport ship; S2: hoisting the base (1): hoisting the base (1) on the transport ship and lowering it to the riverbed surface of the construction sea area; S3: Lifting of foundation pile (3): lifting the foundation pile (3) on the transport ship and gradually turning it over to an upright state; S4: inserting the foundation pile (3): moving the foundation pile (3) to the top of the base (1) and aligning it with the top opening of the corresponding casing (2), then vertically lowering the foundation pile (3), the lower end of the foundation pile (3) passing through the corresponding casing (2) and inserted into the riverbed, repeating the steps of inserting the foundation pile (3) until several foundation piles (3) are inserted; S5: sinking foundation piles (3): hammering the tops of a plurality of foundation piles (3) in sequence to make the plurality of foundation piles (3) firmly fixed in the riverbed, and then connecting and fixing the foundation piles (3) and the casing (2) so that the foundation piles (3) and the base (1) form a pile group composite mooring anchoring system; S6: The rotatable traction mechanism (8) is connected to the offshore floating structure.

7. The method for construction of pile group composite mooring and anchoring for offshore floating structures according to claim 6, characterized in that: In the step of sinking the foundation pile (3) in S5, the pile driving energy is gradually increased from small to large during the pile sinking, and the pile driving energy is increased after the foundation pile (3) is sunk to a certain depth and the pile body of the foundation pile (3) is stable.

8. The method for construction of pile group composite mooring anchoring for offshore floating structures according to claim 6, characterized in that: A self-sealing packer (5) is arranged at the bottom of the casing (2). After the step of sinking the foundation pile (3) of S5 is completed, the inner wall of the casing (2) and the outer wall of the foundation pile (3) form an annular space (10), and the self-sealing packer (5) seals the bottom of the annular space (10). In the step of connecting the foundation pile (3) and the casing (2) of S5, grouting is poured into the annular space (10) to connect the foundation pile (3) and the casing (2).

9. The method for construction of pile group composite mooring and anchoring for offshore floating structures according to claim 6, characterized in that: A plurality of guide plates (9) are distributed around the inner wall of the casing (2), and the length direction of the guide plates (9) is consistent with the length direction of the casing (2). In the step of inserting the foundation piles (3) in S4, the foundation piles (3) are inserted into the seabed under the guidance of the guide plates (9).

10. The method for construction of pile group composite mooring anchoring for offshore floating structures according to claim 6, characterized in that: When the seabed surface of the construction area is a rock layer, after completing the base (1) hoisting step of S2, a drilling platform is built above the base (1), the top surface of the drilling platform is higher than the sea level of the construction area, and then the rock layer of the seabed is drilled from the drilling platform, and the drilling direction is consistent with the axis of the casing (2).

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