A prestressed reinforced steel concrete high-pile pile cap foundation for a wind power tower

Abstract

The application provides a wind power tower prestressed reinforced steel reinforced concrete high-pile pile cap foundation, which comprises a rock-embedded pile foundation, a steel pile cap, post-cast concrete of the pile cap and a prestressed device, the bottom of the rock-embedded pile foundation is a hollow sandwich steel pipe reinforced concrete structure, the steel pile cap is a hollow sandwich steel pipe concrete structure, the bottom of the steel pile cap is provided with a four-cornered shoe beam, the post-cast concrete of the pile cap covers the four-cornered shoe beam at the bottom of the steel pile cap to fix the bottom of the steel pile cap and the top of the rock-embedded pile foundation, and multiple groups of the prestressed device are arranged in the post-cast concrete of the pile cap to increase the integrity of the steel pile cap and the lower rock-embedded pile foundation. The high-pile pile cap foundation solves the problem that stress concentration is serious due to small contact area of the tower drum bottom and the pile cap concrete under cooperative stress, and avoids the problem that the connection part of the tower drum and the pile cap concrete is prone to cracking.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of civil engineering, and particularly to a prestressed stiffened steel-concrete high-pile pile cap foundation for a wind power tower. BACKGROUND

[0002] The soil layer of marine and alluvial deposit has poor physical and mechanical properties, low bearing capacity and uneven thickness distribution, and the underlying weathered rock layer is irregularly distributed and has large fluctuations, so it is suitable to use a high-pile concrete pile cap foundation. This kind of foundation form is composed of pile groups and pile caps, which is borrowed from the pile foundation form of the ship pier and the bridge pier of the cross-sea bridge.

[0003] The traditional high-pile pile cap foundation is composed of a steel pipe pile foundation and a reinforced concrete pile cap. A connecting steel bar is arranged at the top of the steel pipe pile, and is welded with the internal steel reinforcement cage of the pile cap. A stiffening rib is arranged at the bottom of the steel tower cylinder, and a pre-embedded part is embedded in the concrete of the pile cap. The traditional high-pile pile cap foundation uses a steel pipe pile foundation. When the upper tower cylinder of the offshore wind power is high and the weight of the wind turbine is large, a large number of steel pipe piles are needed to increase the bearing capacity of the foundation. At the same time, the top of the steel pipe pile is connected with the internal steel reinforcement cage of the pile cap through a connecting steel bar. The connection performance is greatly affected by the marine environment, which easily leads to connection deterioration. The bottom of the steel tower cylinder is integrally embedded in the concrete pile cap, and only the stiffening rib welded at the bottom of the tower cylinder and the pre-embedded part increase the anchoring force of the tower cylinder and the pile cap, which easily leads to stress concentration at the connection between the tower cylinder and the pile cap, thereby causing large-scale cracking of the ring-shaped concrete of the tower cylinder. The above factors reduce the service life of the offshore wind power equipment. SUMMARY

[0004] In order to solve the problems in the prior art, the present application provides a prestressed stiffened steel-concrete high-pile pile cap foundation for a wind power tower, which is used to solve the problem that the stress concentration phenomenon is serious due to the small contact area of the bottom of the tower cylinder and the concrete of the pile cap, and to avoid the problem that the connection between the tower cylinder and the concrete of the pile cap is easily cracked.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical solution: a prestressed stiffened steel-concrete high-pile pile cap foundation for a wind power tower, comprising a rock-embedded pile foundation, a steel pile cap, pile cap post-cast concrete and a prestressed device. The bottom of the rock-embedded pile foundation is a hollow sandwich steel pipe reinforced concrete structure, and the steel pile cap is a hollow sandwich steel pipe concrete structure. The bottom of the steel pile cap is provided with a four-cornered shoe beam. The pile cap post-cast concrete covers the four-cornered shoe beam at the bottom of the steel pile cap to fix the bottom of the steel pile cap and the top of the rock-embedded pile foundation. A plurality of prestressed devices are arranged in the pile cap post-cast concrete to increase the integrity of the steel pile cap and the lower rock-embedded pile foundation.

[0006] Further, the rock-embedded pile foundation comprises a top cap and a bottom pile foundation. A plurality of bottom pile foundations are fixedly connected at the bottom of the top cap. The axis of the plurality of bottom pile foundations is outwardly provided with an inclination angle. The inclination angle is 3°-15°.

[0007] The top deck is a concrete deck;

[0008] The bottom pile foundation is a hollow sandwiched steel pipe reinforced concrete pile, and the spacing between the plurality of hollow sandwiched steel pipe reinforced concrete piles is at least 1.5 times the diameter of the pile.

[0009] Further, the bottom pile foundation comprises a pile foundation inner steel pipe, a pile foundation outer steel pipe, and a pile foundation sandwiched reinforced concrete, the pile foundation inner steel pipe is arranged in the pile foundation outer steel pipe, the pile foundation sandwiched reinforced concrete is arranged in a sandwich formed by the outer wall of the pile foundation inner steel pipe and the inner wall of the pile foundation outer steel pipe, the top of the pile foundation outer steel pipe is embedded in the top deck, and the bottom is embedded in the bedrock.

[0010] Further, the sandwiched reinforced concrete comprises a spiral steel reinforcement framework and sandwiched concrete, and the sandwiched concrete is used to wrap the spiral steel reinforcement framework.

[0011] The spiral steel reinforcement framework comprises a framework main reinforcement and a top enlarged end, the bottom of the framework main reinforcement is embedded in the bedrock, the top enlarged end is connected with the bottom of the top deck, and the top enlarged end is integrally embedded in the top deck connected therewith.

[0012] Further, the steel deck comprises a tower cylinder and a rigid flange arranged at the top of the tower cylinder, the tower cylinder is a hollow sandwiched steel pipe concrete tower cylinder, the tower cylinder is provided with a four-cornered shoe beam at the bottom, and the bottom of the tower cylinder and the bottom of the four-cornered shoe beam are anchored with the top of the rock-embedded pile foundation.

[0013] Further, the tower cylinder comprises a tower cylinder inner steel pipe, a tower cylinder outer steel pipe, and tower cylinder sandwiched concrete, the tower cylinder inner steel pipe is arranged in the tower cylinder outer steel pipe, and the tower cylinder sandwiched concrete is arranged in a sandwich formed by the outer wall of the tower cylinder inner steel pipe and the inner wall of the tower cylinder outer steel pipe.

[0014] The inner diameter of the flange plate of the rigid flange is equal to the diameter of the tower cylinder inner steel pipe, the outer diameter of the flange plate is greater than the diameter of the tower cylinder outer steel pipe, the flange plate is provided with flange plate stiffening ribs at the bottom, and the two straight edges of the flange plate stiffening ribs are respectively welded with the bottom end face of the flange plate and the outer wall of the tower cylinder outer steel pipe.

[0015] Further, the four-cornered shoe beam is four shoe beams connected by circular arc chamfer transition, the four shoe beams are arranged in four directions at the bottom of the tower cylinder, the shoe beam adopts a wide flange H-shaped steel, one side of the wide flange H-shaped steel is connected with the outer wall of the steel deck, the wide flange H-shaped steel is provided with an anchor rod hole for arranging an anchor rod penetrating through the upper and lower flanges, and rivets are arranged in multiple rows at the top surface of the wide flange H-shaped steel in parallel with the short side of the wide flange H-shaped steel.

[0016] Further, a longitudinal stiffening rib is arranged in the wide flange H-shaped steel in parallel with the upper and lower flanges, the size of the longitudinal stiffening rib is the same as the flange size of the wide flange H-shaped steel, and a plurality of transverse stiffening ribs are arranged in the wide flange H-shaped steel in vertical to the upper and lower flanges.

[0017] Further, the U-shaped steel bars are obtained by combining two vertical steel bars and a horizontal steel bar connected to the top of the two vertical steel bars, the bottom ends of the two vertical steel bars are anchored to the top of the rock-embedded pile foundation, the U-shaped steel bars are entirely covered in the post-cast concrete of the pile cap, and the U-shaped steel bars are arranged at least three in the long edge direction of the shoe beam at equal intervals.

[0018] Further, the prestressing device is provided with four groups, the four groups of prestressing devices are arranged at an interval of 90 degrees along the ring direction, each group is provided with three prestressing tension ends, the prestressing device comprises an end anchorage and a prestressed steel bar, one end of the prestressed steel bar is fastened to the top of the rock-embedded pile foundation, a prestressed hole is arranged in the post-cast concrete of the pile cap, and the other end of the prestressed steel bar is subjected to single-end tension in the prestressed hole through the end anchorage.

[0019] Compared with the prior art, the present application has at least the following beneficial effects:

[0020] The present application provides a prestressed reinforced steel reinforced concrete high-pile pile cap foundation for a wind power tower, which adopts a combined pile cap structure combining a rock-embedded pile foundation of a hollow sandwich steel pipe reinforced concrete structure and a hollow sandwich steel pipe concrete structure steel pile cap, adopts a hollow sandwich structure, and can effectively reduce the self weight of the structure; the pile cap structure fully utilizes the excellent compression and bending resistance of the hollow sandwich steel pipe concrete structure of the steel pile cap, and four corner shoe beams are arranged at the bottom of the steel pile cap to increase the cooperative stress contact area with the rock-embedded pile foundation. Under the action of strong wind load, the compression side increases the compression contact area of the rock-embedded pile foundation and the steel pile cap through the four corner shoe beams, can fully exert the compression resistance of the rock-embedded pile foundation, the tension side disperses the pulling force generated at the connection of the steel pile cap through the four corner shoe beams, the post-cast concrete load of the pile cap provides pre-compression for the four corner shoe beams, effectively controls the deformation of the four corner shoe beams, effectively reduces the tensile stress at the connection of the concrete pile cap and the tower drum, effectively avoids the cracking of the pile cap concrete, and further improves the durability of the pile cap foundation; the pre-compression stress provided by the multiple prestressing devices firmly fixes the steel pile cap between the two layers of concrete by increasing the contact pressure between the rock-embedded pile foundation and the post-cast concrete, the pre-compression stress can effectively balance the tensile stress of the steel pile cap and the top of the rock-embedded pile foundation caused by the upper horizontal load, avoids the cracking of the pile cap concrete, and the size of the pre-compression stress can increase the lateral deformation stiffness, and for the pile cap with anti-collision requirements, the pre-compression stress can be increased in a suitable range according to the design requirements; the pile cap foundation structure of the present application has high integrity, the parts cooperate with each other, fully utilizes the compression resistance of concrete and the tensile resistance of steel, is convenient to construct and easy to assemble, has good practicability and engineering application value.

[0021] The existing high-pile cap foundation mostly adopts a steel pipe pile foundation filled with concrete, and the hollow sandwich structure is adopted in the application, which can effectively reduce the structure self-weight, the spiral steel reinforcement framework is arranged in the sandwich concrete, which can increase the anchoring capacity of the pile body and the foundation, and the increased top section of the spiral steel reinforcement framework helps to increase the embedded capacity with the top cap, the reinforced concrete wrapped by the inner and outer steel pipes has higher bearing performance than the simple cast-in-place concrete, and has advantages in reducing the amount of inner and outer steel materials and improving the structural economy, the sandwich reinforced concrete effectively improves the bearing performance of the pile foundation under the constraint of the outer steel pipe, and improves the buckling resistance of the inner and outer steel pipes.

[0022] The cap foundation of the application adopts a steel tower tube structure as a connecting device of the cap and the upper structure of the wind power, the core hollow sandwich steel pipe concrete tower tube in the center of the steel tower tube can fully play the excellent axial bearing performance and lateral bending resistance of the hollow sandwich steel pipe concrete structure; the boot beam is arranged at the bottom of the steel tower tube to increase the cooperative stress contact area with the cap concrete, the U-shaped steel is arranged on the upper side of the boot beam to increase the anchoring effect of the top cap and the boot beam, which fully reduces the tensile stress distribution in the concrete and effectively avoids the cracking of the top cap concrete.

[0023] The prestress device is buried in the top of the rock-embedded pile foundation on one side of the prestress tension end, and the structure can be pre-pressed by single-end tension after the post-cast concrete construction of the cap is completed, the arrangement of the prestress device increases the integrity of the steel concrete cap and the lower group pile structure, and the application of the prestress is beneficial to reduce the tensile stress in the cap concrete under strong wind load and slow down the cracking of the concrete.

[0024] The flange is arranged at the top of the steel cap of the application, the stiffening rib is arranged at the bottom of the flange to increase the compressive stiffness of the flange, the top surface of the flange is flush with the top surface of the steel tower tube, which facilitates the assembly and connection with the upper tower tube segment of the wind power tower, and is beneficial to improve the construction efficiency of the wind power tower and reduce the wet work on site. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The application is a perspective view;

[0026] Figure 2 The application is a vertical sectional view

[0027] Figure 3 This is a structural diagram of the steel foundation of the present invention;

[0028] Figure 4 This is a structural diagram of the bottom pile foundation of the present invention;

[0029] Figure 5 The figures show the bottom cross-sectional view and vertical section view of the bottom pile foundation of this invention.

[0030] In the attached diagram: 1-Rock-socketed pile foundation, 100-Top pile cap, 101-Bottom pile foundation, 1011-Inner steel pipe of pile foundation, 1012-Outer steel pipe of pile foundation, 1013-Interlayer reinforced concrete, 1014-Spiral steel reinforcement cage, 10141-Main reinforcement of the cage, 10142-Stirrups, 10143-Top enlarged end, 1015-Interlayer concrete, 2-Steel pile cap, 201-Tower, 2011-Inner steel pipe of tower, 2012-Outer steel pipe of tower, 2013-Interlayer concrete of tower, 2 02-Four-corner boot beam, 2021-Wide flange H-beam, 2020-H-beam flange, 20211-H-beam web, 20212-Longitudinal stiffener, 20213-Transverse stiffener, 2022-Anchor bolt, 2023-U-shaped steel bar, 2024-Rivet, 203-Rigid flange, 2031-Flange, 2032-Flange stiffener, 2033-Flange connection hole, 3-Post-cast concrete of foundation, 4-Prestressing device, 401-Anchor, 402-Prestressed steel bar. Detailed Implementation

[0031] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0032] like Figures 1-2 As shown, the present invention provides a prestressed reinforced steel-concrete high-pile foundation for wind turbine towers, applicable to offshore wind power. It includes a rock-socketed pile foundation 1, a steel pile foundation 2, post-cast concrete 3, and prestressing devices 4. The steel pile foundation 2 is set on top of the rock-socketed pile foundation 1. The post-cast concrete 3 covers the bottom of the steel pile foundation 2, fixing the bottom of the steel pile foundation 2 to the top of the rock-socketed pile foundation 1. Multiple sets of prestressing devices 4 are also provided on the top surface of the post-cast concrete 3 to increase the integrity of the steel pile foundation 2 and the lower rock-socketed pile foundation 1.

[0033] like Figures 4-5 As shown, the rock-socketed pile foundation 1 of the present invention includes a top pile cap 100 and a plurality of bottom pile foundations 101 fixedly connected to the top pile cap 100. The top pile cap 100 is a concrete pile cap, and the bottom pile foundations 101 are hollow sandwich steel pipe reinforced concrete piles. The bottom pile foundations 101 adopt a pile group form. The axis of the bottom pile foundations 101 is inclined outward. The diameter of the bottom pile foundations 101 must meet the bearing capacity design requirements. Generally, 8 piles are set.

[0034] Preferably, the bottom pile foundation 101 comprises a pile foundation inner steel pipe 1011, a pile foundation outer steel pipe 1012 and a pile foundation interlayer reinforced concrete 1013, the pile foundation inner steel pipe 1011 is arranged in the pile foundation outer steel pipe 1012, the pile foundation interlayer reinforced concrete 1013 is located in the interlayer formed by the outer wall of the pile foundation inner steel pipe 1011 and the inner wall of the pile foundation outer steel pipe 1012 and is tightly attached to and bonded with the inner and outer steel pipes, the top of the pile foundation outer steel pipe 1012 is embedded in the top pile cap 100, and the bottom is embedded in the bedrock.

[0035] Preferably, the wall thickness of the pile foundation outer steel pipe 1012 needs to meet the corrosion thickness requirement, and the depth of the pile foundation outer steel pipe 1012 buried in the rock layer needs to meet the design requirements of the specification to ensure that the rock-embedded pile foundation 1 has sufficient bearing capacity.

[0036] The interlayer reinforced concrete 1013 comprises a spiral steel reinforcement cage 1014 and an interlayer concrete 1015, the interlayer concrete 1015 is used for coating the spiral steel reinforcement cage 1014 and needs to meet the steel reinforcement cover thickness requirement; the bottom of the spiral steel reinforcement cage 1014 is embedded in the bedrock.

[0037] The spiral steel reinforcement cage 1014 comprises a cage main reinforcement 10141, a stirrup 10142 and a top enlarged end 10143, the cage main reinforcement 10141 needs to meet the design requirements of the pile foundation bearing capacity, the depth of the bottom of the cage main reinforcement 10141 buried in the rock layer needs to meet the design requirements of the specification to ensure that the rock-embedded pile foundation 1 has sufficient bearing capacity; the stirrup 10142 is arranged on the cage main reinforcement 10141, and the arrangement interval thereof needs to meet the requirements of the specification to reduce the amount of steel on the premise of fully exerting the constraint effect of the stirrup; the top enlarged end 10143 is connected with the bottom of the top pile cap 100 and needs to be embedded in the top pile cap 100 connected therewith as a whole.

[0038] Preferably, the inclination angle of the bottom pile foundation 101 is generally 3°-15°, and 5°-10° is recommended; the spacing between the plurality of bottom pile foundations 101 needs to meet at least 1.5 times the diameter of the bottom pile foundation 101.

[0039] As shown in Figure 3 The steel pile cap 2 of the present application comprises a tower drum 201, a four-cornered shoe beam 202 and a rigid flange 203, the tower drum 201 is provided with the rigid flange 203 at the top, the tower drum 201 is welded with the four-cornered shoe beam 202 at the bottom, and the bottom of the tower drum 201 and the bottom of the four-cornered shoe beam 202 are anchored with the upper end surface of the top pile cap 100, and the pile cap post-cast concrete 3 entirely covers the four-cornered shoe beam 202.

[0040] Preferably, the tower drum 201 is a hollow sandwich steel pipe concrete tower drum, including a tower drum inner steel pipe 2011, a tower drum outer steel pipe 2012 and tower drum sandwich concrete 2013, the tower drum inner steel pipe 2011 is arranged in the tower drum outer steel pipe 2012, and the tower drum sandwich concrete 2013 is arranged in a sandwich formed by the outer wall of the tower drum inner steel pipe 2011 and the inner wall of the tower drum outer steel pipe 2012 and tightly adheres to and bonds with the inner and outer steel pipes.

[0041] Preferably, the four-cornered shoe beam 202 is four shoe beams connected through a circular arc chamfer transition form, and the four shoe beams are arranged at four directions of the bottom of the tower drum 201. The shoe beam is composed of a wide flange H-shaped steel 2021, an anchor rod 2022, a U-shaped steel bar 2023 and a rivet 2024. The wide flange H-shaped steel 2021 is provided with an H-shaped steel web 20211, which is welded with the tower drum outer steel pipe 2012 through an H-shaped steel flange 20210 and the H-shaped steel web 20211. The wide flange H-shaped steel 2021 is provided with an anchor rod hole for arranging the anchor rod 2022 penetrating the upper and lower flanges of the wide flange H-shaped steel 2021. The rivet 2024 is arranged at the four corners of the four-cornered shoe beam 202 and is welded to the top surface of the wide flange H-shaped steel 2021, and is arranged in multiple rows at equal intervals and in a direction parallel to the short side of the H-shaped steel flange 20210.

[0042] A plurality of U-shaped steel bars 2023 are also arranged in parallel and at intervals on the shoe beam. The U-shaped steel bar 2023 is obtained by combining two vertical steel bars and a horizontal steel bar connected to the top of the two vertical steel bars. The bottom ends of the two vertical steel bars are anchored in the top slab 100, and the U-shaped steel bar 2023 is entirely covered in the post-cast concrete 3.

[0043] Preferably, the U-shaped steel bars 2023 are arranged at equal intervals along the long side direction of the H-shaped steel flange 2020. It is suggested that the number of arrangements be selected according to the height of the wind turbine tower. In order to satisfy the sufficient anchoring capacity of the steel slab 2 and the rock-embedded pile foundation 1, at least 3 U-shaped steel bars 2023 are arranged at intervals at the four corners of the four-cornered shoe beam 202.

[0044] Preferably, the wide flange H-shaped steel 2021 is provided with a longitudinal stiffener 20212 and a transverse stiffener 20213 with the same thickness and width as the H-shaped steel flange 20210 in the middle. One end of the longitudinal stiffener 20212 is welded with the tower drum outer steel pipe 2012, and the transverse stiffener 20213 is welded with the H-shaped steel flange 20210 and interrupted at the position of the longitudinal stiffener 20212. The arrangement satisfies the requirement of the steel structure specification that the longitudinal and transverse stiffeners intersect with each other.

[0045] Preferably, the anchor rod 2022 has two arrangement forms, which are: circumferentially arranged at the connection between the four-cornered shoe beam 202 and the tower drum 201 and arranged at the four corners of the four-cornered shoe beam 202 and parallel to the short edge of the H-shaped steel.

[0046] The prestress device 4 of the application is composed of end anchorage 401 and prestressed reinforcement 402, the prestressed reinforcement 402 is fastened in the concrete through the anchorage arranged in the top deck 100, and the prestressed reinforcement tension is completed in the prestressed hole arranged on the top of the post-cast concrete 3 in the way of single end tension.

[0047] Preferably, the prestress device 4 is arranged in four groups, each group of prestress device 4 is arranged in 90 degrees along the ring, each group is provided with three prestress tension ends, the prestress tension end is located on the post-cast concrete layer 3, the end anchorage 401 selected for the prestress tension end should be provided with no less than six prestress anchoring holes, and the end anchorage 401 needs to be sealed after the tension of the prestressed reinforcement 402 is completed.

[0048] The inner diameter of the flange plate 2031 of the rigid flange 203 of the application is equal to the diameter of the inner steel pipe 2011 of the tower drum, the outer diameter of the flange plate 2031 should be greater than the diameter of the outer steel pipe 2012 of the tower drum by 200-300 mm, the flange plate 2031 is provided with flange plate stiffening ribs 2032 at the bottom, and the two straight angle edges of the flange plate stiffening ribs 2032 are welded with the bottom end face of the flange plate 2031 and the outer wall face of the outer steel pipe 2012 of the tower drum respectively.

[0049] The construction method of the high-pile deck foundation of the application is as follows:

[0050] (1) The spiral reinforcement framework 1014 of the bottom pile foundation 101 is positioned by using the short steel reinforcement welding method and the inner steel pipe 1011 and the outer steel pipe 1012 of the pile foundation, so as to ensure that the relative positions of the three are consistent with the design, and the relative positions of the three need to meet that the three axes of the spiral reinforcement framework 1014, the inner steel pipe 1011 and the outer steel pipe 1012 of the pile foundation are located on the same straight line.

[0051] (2) The fixed spiral reinforcement framework 1014, the inner steel pipe 1011 and the outer steel pipe 1012 of the pile foundation are hoisted to the designated installation position, the main reinforcement 10141 of the framework and the bottom of the outer steel pipe 1012 of the pile foundation are pre-buried in the rock layer, the installation position of the pile foundation is adjusted according to the design angle of the pile body, the interlayer concrete 1015 can be poured after the pile foundation is embedded, and the bottom pile foundation 101 is obtained when the interlayer concrete 1015 meets the design strength requirement, and the construction of the top deck 100 is carried out after the bottom pile foundation 101 has sufficient bearing capacity.

[0052] (3) When the top deck 100 is constructed, the concrete pouring formwork is installed at the top of the pile foundation, the U-shaped reinforcement 2023 is constructed by using the sectional welding method, the straight rod reinforcement on both sides of the U-shaped reinforcement 2023 and the anchor rod 2022 are pre-buried in the top deck 100, the steel deck 2 is hoisted after the concrete reaches the design strength, the steel deck 2 and the four-cornered shoe beam 202 are pre-welded, and the four-cornered shoe beam 202 is pre-provided with an anchor rod channel.

[0053] (4) Use a floating crane or other hoisting equipment to hoist the steel pier 2, hoist the steel pier 2 to the designated position, pass the anchor rod 2022 through the anchor rod hole reserved in the four corner shoe beam 202, and fix the anchor rod by using nuts or end welding. Use straight steel bars of the same diameter to weld the straight rods on both sides of the U-shaped steel bar to complete the closure of the U-shaped steel bar 2023.

[0054] (5) After the hoisting and assembly of the steel foundation 2 is completed, the concrete 3 of the foundation is constructed by using the formwork erection and in-situ concrete pouring method. When the concrete is poured, the tensioning holes and anchor installation positions of the prestressed steel bars are reserved. After the concrete of the foundation reaches the design strength, the six prestressed steel bars 402 are tensioned by single-sided tensioning in the reserved prestressed steel bar tensioning holes. The ends are fixed by anchor 401. After all the prestressed steel bars are tensioned, the anchoring work of the tensioning end is completed at the anchor installation position.

[0055] The working principle of this invention is as follows:

[0056] This invention fully utilizes the excellent axial compression and bending resistance of hollow steel-concrete composite structures. Furthermore, because the hollow steel tube structure is similar to that of traditional steel pipe piles, it facilitates pile positioning and construction. Based on this, a spiral steel reinforcement cage 1014 is arranged within the concrete sandwich layer, increasing the anchorage capacity between the pile and the foundation. Simultaneously, the increased top cross-section of the spiral steel reinforcement cage 1014 helps to enhance its embedment capacity with the top bearing cap 100. The reinforced concrete encased in inner and outer steel tubes has higher load-bearing capacity than simply poured concrete, offering advantages in reducing the amount of inner and outer steel used and improving structural economy. Under the constraint of the external steel tubes, the reinforced concrete sandwich layer effectively improves the load-bearing capacity of the pile foundation and simultaneously enhances the buckling resistance of the inner and outer steel tubes. When there are large horizontal and vertical loads in the upper load, the load is transferred to the pile body through the concrete of the top pile cap. The hollow sandwich structure reduces the distribution area of ​​the concrete and increases the cross-sectional area of ​​the steel pipe, which improves the bending and torsional moment of inertia of the section. It can effectively share the load of the upper load in all directions and avoid failure due to insufficient bearing capacity of the pile foundation. The spiral steel reinforcement cage 1014 set in the concrete can increase the anchorage capacity between the pile foundation and the rock strata when the horizontal load is large. Because the steel reinforcement is distributed closer to the center of the section than the steel pipe 1012 of the hollow sandwich reinforced concrete pile foundation, the tensile stress it bears is significantly lower than that of the steel pipe 1012 of the hollow sandwich reinforced concrete pile foundation.

[0057] The application takes full advantage of the performance advantages of concrete and steel, and the four-cornered shoe beam 202 is arranged at the bottom of the steel pile cap 2, thereby increasing the contact area between the original tower drum bottom and the pile cap, under the action of the upper load, the tower drum 201 of the steel pile cap 2 bears almost all the vertical load, and the bottom area of the four-cornered shoe beam 202 is expanded to increase the distribution area of the vertical pressure, when the upper load contains a horizontal force, the stress state of the beam end of the four-cornered shoe beam 202 appears a similar tension-compression stress mode, because the bottom of the four-cornered shoe beam 202 has a large contact area with the pile cap concrete, the stress change of the pile cap concrete is small, when the horizontal force component is further increased, the upper U-shaped steel bars 2023 and anchor rods 2023 of the four corners of the four-cornered shoe beam 202 further constrain the shoe beam from being lifted up, and the post-cast concrete 3 of the pile cap provides pre-pressure for the four-cornered shoe beam 202, effectively controls the deformation of the four-cornered shoe beam 202, effectively reduces the tensile stress at the connection between the concrete pile cap and the tower drum, and can significantly improve the service life of the structure.

[0058] The application provides pre-tensioning stress for the steel reinforced concrete pile cap by reserving the anchorage device 401 and the pre-tensioning steel bar 402 hole installation position in the pile top cap concrete, fixing the anchorage device 401 in the pile top cap concrete 100, and tensioning the pre-tensioning steel bar 402 in the pre-tensioning steel bar hole reserved at the top of the post-cast concrete 3 in a single-end tensioning mode, the pre-tensioning stress provided by the pre-tensioning steel bar 402 firmly fixes the steel pile cap 2 between the two layers of concrete by increasing the contact pressure between the top cap 100 and the post-cast concrete 3, the pre-tensioning stress causes a certain compressive stress between the top cap 100 and the steel pile cap 2 and between the steel pile cap 2 and the post-cast concrete 3 of the pile cap, the compressive stress can effectively balance the tensile stress between the steel pile cap 2 and the top cap 100 caused by the upper horizontal load, avoids the cracking of the pile cap concrete, and the pre-tensioning stress size can increase the lateral deformation stiffness, and for the pile cap with anti-collision requirements, the pre-tensioning stress can be increased in a proper range according to the design requirements.

Claims

1. A wind power tower prestressed reinforced steel concrete high-pile pile cap foundation, characterized in that, The embedded rock pile foundation (1), the steel cap (2), the post-cast concrete (3) and the prestressed device (4) are included, the bottom of the embedded rock pile foundation (1) is a hollow sandwich steel pipe reinforced concrete structure, the steel cap (2) is a hollow sandwich steel pipe concrete structure, the bottom of the steel cap (2) is provided with a four-cornered shoe beam (202), the post-cast concrete (3) covers the four-cornered shoe beam (202) at the bottom of the steel cap (2) to fix the bottom of the steel cap (2) and the top of the embedded rock pile foundation (1), and a plurality of groups of prestressed devices (4) are arranged in the post-cast concrete (3) to increase the integrity of the steel cap (2) and the lower embedded rock pile foundation (1); The steel cap (2) includes a tower cylinder (201) and a rigid flange (203) arranged at the top of the tower cylinder (201), the tower cylinder (201) is a hollow sandwich steel pipe concrete tower cylinder, the bottom of the tower cylinder (201) is provided with a four-cornered shoe beam (202), and the bottom of the tower cylinder (201) and the bottom of the four-cornered shoe beam (202) are anchored to the top of the embedded rock pile foundation (1); The four-cornered shoe beam (202) is four shoe beams connected through circular arc chamfer transition, the four shoe beams are arranged in four directions at the bottom of the tower cylinder (201), the shoe beam adopts a wide flange H-shaped steel (2021), one side of the wide flange H-shaped steel (2021) is connected with the outer wall of the steel cap (2), the wide flange H-shaped steel (2021) is provided with an anchor rod hole for arranging an anchor rod (2022) penetrating the upper and lower flanges, a plurality of rows of rivets (2024) are arranged on the top surface of the wide flange H-shaped steel (2021) in parallel with the short side of the wide flange H-shaped steel (2021); The wide flange H-shaped steel (2021) is provided with a longitudinal stiffening rib (20212) parallel to the upper and lower flanges, the size of the longitudinal stiffening rib (20212) is the same as the flange size of the wide flange H-shaped steel (2021), and a plurality of transverse stiffening ribs (20213) are arranged in the wide flange H-shaped steel (2021) in parallel to the upper and lower flanges; The U-shaped steel bar (2023) is obtained by combining two vertical steel bars and a horizontal steel bar connected with the top of the two vertical steel bars, the bottom ends of the two vertical steel bars are anchored to the top of the embedded rock pile foundation (1), the U-shaped steel bar (2023) is entirely covered in the post-cast concrete (3), and at least three U-shaped steel bars (2023) are arranged at equal intervals along the long side direction of the shoe beam; The prestressed device (4) is arranged in four groups, the four groups of prestressed devices (4) are arranged at an interval of 90° along the ring direction, each group is provided with three prestressed tension ends, the prestressed device (4) includes an end anchor (401) and a prestressed steel bar (402), one end of the prestressed steel bar (402) is fastened to the top of the embedded rock pile foundation (1), a prestressed hole is arranged in the post-cast concrete (3), and the other end of the prestressed steel bar (402) is subjected to single-end tension in the prestressed hole through the end anchor (401).

2. The prestressed reinforced steel concrete high-pile pile cap foundation for a wind power tower according to claim 1, characterized in that, The rock-embedded pile foundation (1) comprises a top bearing platform (100) and a bottom pile foundation (101), a plurality of bottom pile foundations (101) are fixedly connected at the bottom of the top bearing platform (100), and the plurality of bottom pile foundations (101) are provided with an inclination angle along the axis outward, and the inclination angle is 3°-15°. The top bearing platform (100) is a concrete bearing platform. The bottom pile foundation (101) is a hollow sandwiched steel pipe reinforced concrete pile, and the spacing between the plurality of hollow sandwiched steel pipe reinforced concrete piles is at least 1.5 times the pile diameter.

3. The prestressed reinforced steel concrete high-pile pile cap foundation of a wind power tower according to claim 2, characterized in that, The bottom pile foundation (101) comprises a pile foundation inner steel pipe (1011), a pile foundation outer steel pipe (1012) and a pile foundation sandwiched reinforced concrete (1013), the pile foundation inner steel pipe (1011) is arranged in the pile foundation outer steel pipe (1012), the pile foundation sandwiched reinforced concrete (1013) is located in the sandwiched layer formed by the outer wall of the pile foundation inner steel pipe (1011) and the inner wall of the pile foundation outer steel pipe (1012), the top of the pile foundation outer steel pipe (1012) is embedded in the top bearing platform (100), and the bottom is embedded in the bedrock.

4. The prestressed reinforced steel concrete high-pile pile cap foundation of a wind power tower according to claim 3, characterized in that, The sandwiched reinforced concrete (1013) comprises a spiral steel reinforcement framework (1014) and a sandwiched concrete (1015), and the sandwiched concrete (1015) is used for coating the spiral steel reinforcement framework (1014). The spiral steel reinforcement framework (1014) comprises a framework main reinforcement (10141) and a top enlarged end (10143), the bottom of the framework main reinforcement (10141) is embedded in the bedrock, the top enlarged end (10143) is connected with the bottom of the top bearing platform (100), and the top enlarged end (10143) is embedded in the top bearing platform (100) connected therewith as a whole.

5. The prestressed reinforced steel concrete high-pile pile cap foundation of a wind power tower according to claim 1, characterized in that, The tower cylinder (201) comprises a tower cylinder inner steel pipe (2011), a tower cylinder outer steel pipe (2012) and a tower cylinder sandwiched concrete (2013), the tower cylinder inner steel pipe (2011) is arranged in the tower cylinder outer steel pipe (2012), and the tower cylinder sandwiched concrete (2013) is arranged in the sandwiched layer formed by the outer wall of the tower cylinder inner steel pipe (2011) and the inner wall of the tower cylinder outer steel pipe (2012); The inner diameter of the flange plate (2031) of the rigid flange (203) is equal to the diameter of the tower cylinder inner steel pipe (2011), the outer diameter of the flange plate (2031) is greater than the diameter of the tower cylinder outer steel pipe (2012), the bottom of the flange plate (2031) is provided with a flange plate stiffening rib (2032), and the two straight angle edges of the flange plate stiffening rib (2032) are respectively welded with the bottom end face of the flange plate (2031) and the outer wall face of the tower cylinder outer steel pipe (2012).

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