Design and construction method for concrete-filled pipe-mixed soil-cement composite pile foundation for offshore wind power

Abstract

A design and construction method for a concrete-filled pipe-mixed soil-cement composite pile foundation for offshore wind power, comprising: on the basis of a load requirement of offshore wind power equipment and the depth of seawater, selecting a supporting body that is adapted to the offshore wind power equipment, one of a bearing platform (4) or a multi-leg frame (15) being used for the supporting body; when a bearing platform (4) is used as the supporting body, constructing multiple concrete-filled pipe-mixed soil-cement composite piles (6) below the bearing platform (4), the multiple concrete-filled pipe-mixed soil-cement composite piles (6) each being obliquely arranged below the bearing platform (4) at a certain angle, and forming an outwardly-inclined scattered shape; and when a multi-leg frame (15) is used as the supporting body, constructing multiple concrete-filled pipe-mixed soil-cement composite piles (6) below the bearing platform (4), the multiple concrete-filled pipe-mixed soil-cement composite piles (6) being vertically arranged below the multi-leg frame (15).

Description

A design and construction method for steel tube concrete mixing composite pile foundation for offshore wind power Technical Field

[0001] The present invention relates to the technical field of offshore wind power foundations, and in particular to a design and construction method of a steel tube concrete mixing composite pile foundation for offshore wind power. Background Art

[0002] Offshore wind power foundation has always been the focus and difficulty of offshore wind power projects. There are eight main types of offshore wind power foundation structures, namely single pile foundation, high pile foundation, jacket foundation, gravity foundation, tripod foundation, as well as bucket foundation, floating foundation and suction foundation. The most commonly used ones in China today are steel pipe pile single pile or high pile foundation.

[0003] Due to the large wind load at sea, these two types of foundation steel pipe piles are relatively large, that is, the diameter and pile length are both large. The maximum diameter of the steel pipe pile can reach 10m, the pile length ranges from tens of meters to nearly 100 meters, and the weight is more than a thousand tons. In addition, the construction site is located at sea. The huge steel pipe piles have caused great difficulties in marine transportation, lifting, piling, and other construction processes, and the cost is high. In the marine environment, corrosion protection of steel pipes is also a difficult problem to deal with. Summary of the Invention

[0004] The present invention addresses the deficiencies of the prior art and provides a design and construction method for a steel tube concrete mixing composite pile foundation for offshore wind power. In the composite pile, friction is provided by an outer cement-soil mixing pile in the seabed soil layer for an inner steel tube concrete core pile. Due to the restraining effect of the steel tube, the concrete inside the steel tube is subjected to a three-dimensional stress state. The pile body bearing capacity is significantly improved compared to ordinary concrete or pure steel tubes. At the same time, the overall stiffness, bending resistance, and impact resistance are significantly improved. The cross-sectional size of the steel tube can be significantly reduced, greatly facilitating the transportation and lifting of pile foundation materials. The piling process is also saved, significantly reducing the material and construction costs of the pile foundation. Furthermore, under the protection of the inner concrete and the outer cement-soil mixing pile, the corrosion resistance of the steel tube in the composite pile foundation is also significantly improved. The cyclic load fatigue resistance of the steel tube concrete structure is significantly improved compared to the hollow steel tube structure, significantly extending the design life of the pile foundation. The high stiffness of the steel tube concrete structure makes the foundation suitable for deeper waters. The composite pile foundation has significant technical and economic advantages over traditional offshore wind power foundations.

[0005] The purpose of the present invention is achieved by the following technical solutions:

[0006] A design and construction method for a steel tube concrete mixing composite pile foundation for offshore wind power, used to support offshore wind power equipment, wherein the offshore wind power equipment includes a wind turbine, wind turbine blades, and a tower, characterized in that the design and construction method comprises the following steps:

[0007] Selecting a support body that is compatible with the offshore wind turbine according to the load requirements of the offshore wind turbine and the depth of the seawater. The support body is used to connect with the tower to support the offshore wind turbine, and is a support platform or a multi-legged frame.

[0008] In the case where the cap is used as the support, a plurality of steel tube concrete mixing composite piles are constructed below the cap, and the plurality of steel tube concrete mixing composite piles are arranged below the cap at a certain angle and form an outward inclined scattering shape;

[0009] In the case where the tripod is used as the support body, a plurality of steel tube concrete mixing composite piles are constructed below the cap, and the plurality of steel tube concrete mixing composite piles are vertically arranged below the tripod;

[0010] The bottom of the steel tube concrete mixing composite pile is inserted into the seabed soil layer, and the part inserted into the seabed soil layer includes a mixing pile and a steel tube concrete core pile from the outside to the inside. The steel tube concrete core pile is composed of a steel tube and concrete poured inside it. The part of the steel tube concrete mixing composite pile located in the seawater between the sea surface and the seabed is a steel tube concrete pile.

[0011] When the cap is used as the support body, adjacent steel tube concrete mixing composite piles are connected by steel tube trusses to connect several steel tube concrete mixing composite piles to form an integral structure.

[0012] The steel tube truss includes a hoop and a truss rod connected to the hoop, and the hoop is fixed on the periphery of the steel tube concrete mixing composite pile; the adjacent steel tube concrete mixing composite piles are respectively provided with the hoop, and the hoop is connected and fixed by the truss rod to form an integral structure.

[0013] The multi-legged stand has supporting legs corresponding to the number of the steel tube concrete mixing composite piles, and the steel tube concrete piles of each steel tube concrete mixing composite pile are connected to each supporting leg in a one-to-one correspondence.

[0014] The advantages of the present invention are:

[0015] 1) Reasonable structural stress, reducing foundation cost and construction difficulty: Steel tube concrete mixing composite piles, with friction provided by external large-diameter mixing piles and pile bearing capacity provided by internal steel tube concrete core piles; Steel tube concrete core piles, due to the restraining effect of the steel tube, put the concrete in the steel tube in a three-dimensional stress state, and its pile bearing capacity is greatly improved compared with ordinary concrete or pure steel tube piles. When bearing the same load, the diameter of the steel tube can be greatly reduced, reducing the material cost of the pile foundation; at the same time, it can be constructed in sections, which greatly reduces the cost of offshore transportation and hoisting compared with conventional large-diameter long steel tube piles for offshore wind power foundations; at the same time, the pile foundation adopts the mixing and sinking process, which does not require offshore piling, greatly reducing the difficulty and cost of pile sinking; this pile type effectively reduces costs in terms of materials, offshore transportation, hoisting, piling, etc., and the comprehensive cost has obvious advantages over conventional steel tube pile foundations.

[0016] 2) Improve foundation corrosion resistance: Steel tube concrete mixing composite piles, with the steel tube wrapped in concrete inside the tube and cement soil outside the tube, greatly improve its corrosion resistance in the marine environment.

[0017] 3) Good fatigue resistance: Compared with pure steel pipe pile structure, steel tube concrete structure has obvious advantages in fatigue resistance under cyclic load, which can significantly improve the foundation's ability to resist structural fatigue.

[0018] 4) Improving the service life of the foundation: Corrosion resistance and structural fatigue resistance are key factors affecting the service life of offshore wind power foundations. Due to the high corrosiveness of seawater, the current hollow steel pipe piles are severely corroded. At the same time, the long-term vibration loads during the operation of wind turbines, and the back-and-forth impact of waves, sea ice, and sea breeze on the foundations make the offshore wind power foundations bear large cyclic loads. The current design life of offshore wind power foundations is generally 25-30 years. The steel tube concrete mixing composite pile structure has significantly enhanced corrosion resistance and structural fatigue resistance, which can effectively extend the service life of the offshore wind power foundation, increase its power generation during its service life, and thus reduce the comprehensive cost per kilowatt-hour of offshore wind power.

[0019] 5) Strong structural impact resistance: Compared with hollow steel tube structures, steel tube concrete structures have greatly improved impact resistance and bending resistance due to the presence of solid concrete inside. They can effectively resist the impact of harsh external conditions such as waves, tides, sea ice, and sea breezes.

[0020] 6) High structural rigidity, strong stability, and applicable to large seawater depths: The steel tube concrete column has high structural rigidity and is an integrated structure with the steel tube concrete mixing composite piles below the seabed. Its overall stability is significantly improved compared to the hollow steel tube high pile cap foundation. At the same time, since the steel tube concrete column body has good circumferential compressive strength, the steel tube concrete columns can be connected into a truss system using sleeve bolts on site. After adding the steel tube truss, the stability of the pile cap foundation can be greatly improved, so that this structure can be used in areas with relatively deep sea water, greatly increasing the water depth of fixed foundations for offshore wind power, and creating technical conditions for offshore wind power to move to the deep sea. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] FIG1 is a schematic structural diagram of a first embodiment of the present invention;

[0022] FIG2 is a detailed schematic diagram of the first embodiment of the present invention;

[0023] FIG3 is a schematic diagram of an end portion of a first embodiment of the present invention;

[0024] FIG4 is a schematic cross-sectional view of a composite pile in Example 1 of the present invention;

[0025] FIG5 is a schematic structural diagram of a combined truss according to an embodiment of the present invention;

[0026] FIG6 is a schematic diagram of the connection structure of the trusses in the first embodiment of the present invention;

[0027] FIG7 is a schematic structural diagram of a second embodiment of the present invention;

[0028] FIG8 is a detailed schematic diagram of a second embodiment of the present invention;

[0029] FIG9 is a schematic diagram of an end portion of a second embodiment of the present invention;

[0030] FIG10 is a schematic cross-sectional view of a composite pile in Example 2 of the present invention;

[0031] FIG11 is a construction step diagram I of Example 1 of the present invention;

[0032] FIG12 is a construction step diagram II of Example 1 of the present invention;

[0033] FIG13 is a construction step diagram III of the first embodiment of the present invention;

[0034] FIG14 is a construction step diagram IV of the first embodiment of the present invention. DETAILED DESCRIPTION

[0035] The features of the present invention and other related features are further described in detail below through embodiments in conjunction with the accompanying drawings to facilitate understanding by those skilled in the art:

[0036] As shown in Figure 1-14, the marks 1-24 in the figure respectively represent: wind turbine 1, wind turbine blades 2, tower 3, foundation 4, steel tube concrete pile 5, steel tube concrete mixing composite pile 6, concrete 7, steel pipe 8, mixing pile cement soil 9, mixing head 10, steel tube truss 11, hoop 12, truss rod 13, bolt 14, steel tripod 15, cement slurry pump 16, grouting hose 17, grouting steel pipe 18, rotary power head 19, construction platform 20, frame 21, steel pipe joint 22, grouting steel pipe joint 23, concrete preparation pumping ship 24.

[0037] Embodiment 1: As shown in Figures 1 to 6, in this embodiment, the high-pile-capped steel tube concrete mixing composite pile foundation for offshore wind power is used to support offshore wind power equipment, which includes a wind turbine group 1, wind turbine blades 2 and a tower 3, wherein the wind turbine blades 2 are installed on the wind turbine group 1 to collect wind energy, and the wind turbine group 1 is used to convert wind energy into electrical energy, and the tower 3 is arranged below the wind turbine group 1.

[0038] Specifically, in combination with Figures 1 to 4, the main body of the high-pile pedestal steel tube concrete mixing composite pile foundation for offshore wind power in this embodiment includes a pedestal 4 as a supporting body and a number of steel tube concrete mixing composite piles 6, wherein the several steel tube concrete mixing composite piles 6 are arranged at the lower part of the pedestal 4 and each steel tube concrete mixing composite pile 6 is arranged at a certain angle, so that the several steel tube concrete mixing composite piles 6 are arranged in a scattered manner below the pedestal 4 to effectively support the pedestal 4, and the tower 3 is supported above the pedestal 4.

[0039] In this embodiment, the pile foundation located at the bottom of the pedestal 4 includes a steel tube concrete pile 5 and a steel tube concrete mixing composite pile 6, wherein the steel tube concrete pile 5 is located in the sea water between the sea surface and the seabed, and serves as the core pile part of the steel tube concrete mixing composite pile 6, while the steel tube concrete mixing composite pile 6 is inserted into the seabed soil layer, which includes a composite pile of the steel tube concrete pile 5 and the mixing pile cement soil 9 (mixing pile).

[0040] Specifically, the steel tube concrete pile 5 comprises a steel tube 8 and concrete 7 poured within it. Due to the restraining effect of the steel tube 8, the concrete 7 is subjected to a three-dimensional stress state. The outer mixing pile cement soil 9 in the seabed soil layer provides friction for the inner steel tube concrete pile 5, significantly improving the pile body's bearing capacity, overall stiffness, bending resistance, and impact resistance. This can significantly reduce the cross-sectional dimensions of the steel tube, greatly facilitating the transportation and hoisting of pile foundation materials, while also saving the piling process and significantly reducing the material and construction costs of the pile foundation. Furthermore, the steel tube 8 of the steel tube concrete mixing composite pile 6 located within the seabed soil layer, protected by the internal concrete 7 and the outer mixing pile cement soil 9, has significantly improved corrosion resistance. The fatigue resistance of the steel tube concrete structure is also significantly improved compared to a pure steel structure, effectively extending the service life of the offshore wind power foundation.

[0041] As shown in FIG3 , in this embodiment, during the construction of the cement-soil mixing pile 9 , the cement slurry is fully mixed with the soil of the seabed soil layer by the mixing head 10 to form cement-soil.

[0042] As shown in FIG5 , in order to further improve the supporting effect of the foundation 4 and the offshore wind turbine equipment above, a steel tube truss 11 can be provided between the steel tube concrete piles 5 to connect the steel tube concrete piles 5 to form an integral structure.

[0043] Specifically, as shown in Figure 6, the steel tube truss 11 includes a hoop 12, a truss member 13, and a bolt 14. The hoop 12 is a semi-ring-shaped structure that can be opened. Once opened, it can encircle the outer periphery of the steel tube 8. Bolts 14 then connect and secure the two semi-ring structures, allowing the hoop 12 to be fixed to the steel tube concrete pile 5. The truss member 13 is used to connect the hoop 12 on two adjacent steel tube concrete piles 5, thereby connecting and securing the adjacent steel tube concrete piles 5 to form a whole. To improve the use effect, the truss member 13 can be divided into horizontal members and diagonal members to improve the integrity of the steel tube concrete piles 5.

[0044] During construction, as shown in Figures 11 to 14, this embodiment includes the following steps:

[0045] 1) Build a construction platform 20 and set up various construction equipment on the construction platform 20.

[0046] 2) The rotary power head 19 holds the steel pipe 8 and rotates, driving the bottom mixing head 10 to rotate and cut the soil. At the same time, the cement slurry pump 16 sprays cement slurry to the mixing head 10 through the grouting hose 17 and the grouting steel pipe 18. The pile head soil is fully mixed with the cement slurry under the stirring of the mixing head 10 to form cement soil. At the same time, the frame 21 drives the steel pipe 8 and the mixing head 10 to sink while stirring in the soil (this process is similar to that of mixing piles). If re-mixing is required, the frame 21 can also drive the steel pipe 8 and the mixing head 10 to reciprocate up and down to complete the re-mixing.

[0047] 3) After completing the construction of a steel pipe 8 mixing pile, if the pile length does not reach the designed pile length, it can be connected through the steel pipe joint 22 and the grouting steel pipe joint 23 to construct the next section of steel pipe mixing pile until the designed pile length is reached.

[0048] 4) After the mixing pile is constructed to the designed pile length, the frame 21 is removed and concrete 7 is poured into the hollow steel pipe 8 using a concrete preparation pumping ship 24 to form a steel tube concrete mixing composite pile 6.

[0049] 5) Construct a cap 4 on top of several steel tube concrete mixing composite piles 6.

[0050] Embodiment 2: As shown in FIG. 7 to FIG. 10 , this embodiment differs from the embodiment 1 in that the support body of the offshore wind power equipment is selected differently and different steel tube concrete mixing composite piles 6 are arranged in a targeted manner.

[0051] Specifically, as shown in Figures 7 to 10, the foundation body in this embodiment includes a steel tripod 15 as a support body and a plurality of steel tube concrete mixing composite piles 6. The plurality of steel tube concrete mixing composite piles 6 are disposed below the steel tripod 15 and are arranged vertically to effectively support the steel tripod 15. The tower 3 is supported above the steel tripod 15. In this embodiment, the steel tripod 15 has three symmetrically arranged legs, each of which is connected to a corresponding steel tube concrete pile 5 of the steel tube concrete mixing composite pile 6.

[0052] In this embodiment, the pile foundation located at the bottom of the steel tripod 4 includes a steel tube concrete pile 5 and a steel tube concrete mixing composite pile 6, wherein the steel tube concrete pile 5 is located in the sea water between the sea surface and the seabed and serves as the core pile part of the steel tube concrete mixing composite pile 6, while the steel tube concrete mixing composite pile 6 is inserted into the seabed soil layer and includes a composite pile of the steel tube concrete pile 5 and the mixing pile cement soil 9 (mixing pile).

[0053] When the above embodiments are implemented, both structural forms can be used under geological conditions where the seabed soil layer is relatively thick. When the pedestal 4 is used as a support body in conjunction with the inclined steel tube concrete mixing composite piles 6, it can be used under conditions with large wind and electric loads. The steel tube truss 11 can play a reinforcing role. When the seawater depth is large and the steel tube concrete column is long in water, and its stability is required to be high, its stability in seawater can be improved by adding the steel tube truss 11. When the steel tripod 15 (multi-legged leg) is used as a support body in conjunction with the vertically arranged steel tube concrete mixing composite piles 6, the use of vertical piles makes construction more convenient.

[0054] Although the above embodiments have described the concepts and embodiments of the present invention in detail with reference to the accompanying drawings, ordinary technicians in this field can recognize that various improvements and modifications can still be made to the present invention without departing from the scope of the claims, so they are not described in detail here.

Claims

1. A design and construction method for a steel tube concrete mixing composite pile foundation for offshore wind power, used to support offshore wind power equipment, wherein the offshore wind power equipment includes a wind turbine, wind turbine blades, and a tower, characterized by: The design and construction method comprises the following steps: Selecting a support body that is compatible with the offshore wind turbine according to the load requirements of the offshore wind turbine and the depth of the seawater. The support body is used to connect with the tower to support the offshore wind turbine, and is a support platform or a multi-legged frame. In the case where the cap is used as the support, a plurality of steel tube concrete mixing composite piles are constructed below the cap, and the plurality of steel tube concrete mixing composite piles are arranged below the cap at a certain angle and form an outward inclined scattering shape; In the case where the tripod is used as the support body, a plurality of steel tube concrete mixing composite piles are constructed below the cap, and the plurality of steel tube concrete mixing composite piles are vertically arranged below the tripod; The bottom of the steel tube concrete mixing composite pile is inserted into the seabed soil layer, and the part inserted into the seabed soil layer includes a mixing pile and a steel tube concrete core pile from the outside to the inside. The steel tube concrete core pile is composed of a steel tube and concrete poured inside it. The part of the steel tube concrete mixing composite pile located in the seawater between the sea surface and the seabed is a steel tube concrete pile.

2. The design and construction method of a steel tube concrete mixing composite pile foundation for offshore wind power according to claim 1, characterized in that: When the cap is used as the support body, adjacent steel tube concrete mixing composite piles are connected by steel tube trusses to connect several steel tube concrete mixing composite piles to form an integral structure.

3. The design and construction method of a steel tube concrete mixing composite pile foundation for offshore wind power according to claim 2, characterized in that: The steel tube truss includes a hoop and a truss rod connected to the hoop, and the hoop is fixed on the periphery of the steel tube concrete mixing composite pile; the adjacent steel tube concrete mixing composite piles are respectively provided with the hoop, and the hoop is connected and fixed by the truss rod to form an integral structure.

4. The design and construction method of a steel tube concrete mixing composite pile foundation for offshore wind power according to claim 1, characterized in that: The multi-legged stand has supporting legs corresponding to the number of the steel tube concrete mixing composite piles, and the steel tube concrete piles of each steel tube concrete mixing composite pile are connected to each supporting leg in a one-to-one correspondence.

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