A steel-concrete composite tower and its construction method

Abstract

The present invention provides a steel-concrete composite tower, including a steel tower, a concrete tower and a foundation. The concrete tower is composed of multiple concrete tower segments. The concrete tower segments are formed by enclosing multiple tower segment slices with each other. The tower segment slices are composed of left convex plates and right convex plates that are staggered from top to bottom. The connecting line between the left convex plate and the right convex plate is staggered by a distance equal to the thickness of a tower segment slice. The tower segment slices are connected by embedded parts screws. By arranging the staggered tower segment slices, the mechanical properties and stability of the composite tower can be improved. During the construction process, the prestressed cable is hoisted to the predetermined position at one time by using a positioning tooling, reducing the construction period. The construction method of the whole construction process is simple, saving costs.

Description

Technical Field

[0001] The present invention relates to the technical field of wind power generation, and in particular to a combined tower and a construction method thereof. Background Art

[0002] There are various types of towers for wind turbines. Steel towers are difficult to meet the needs of large-scale wind turbines and low wind speed areas in the wind power market due to their high cost and transportation difficulties. Currently, combined towers composed of prestressed assembled concrete towers and steel towers have become a more commonly used solution. Concrete tower sections are generally composed of multiple prefabricated tower section segments. Therefore, the connection between concrete tower sections and steel tower sections, the processing efficiency when prefabricating tower section segments, the convenience of splicing, and the stress performance and overall stability of the entire tower after splicing have become problems that need to be solved for combined towers. Summary of the invention

[0003] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide a steel-concrete composite tower and a construction method thereof, so as to achieve the purpose of rapid installation and molding of the tower and improve the mechanical properties and stability of the composite tower structure. In addition, the concrete tower only needs one set of molds, which improves the processing efficiency of the prefabricated tower and reduces the initial investment and on-site construction period.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] A steel-concrete composite tower comprises a steel tower, a concrete tower and a foundation, wherein the concrete tower is composed of multiple concrete tower segments, and is characterized in that the concrete tower segments are formed by a plurality of identical tower segment slices enclosed by each other, wherein the tower segment slices are composed of left convex plates and right convex plates staggered from top to bottom, wherein the contact surfaces of the left convex plates and the right convex plates are staggered left and right by a distance equal to the thickness of the tower segment, and the tower segment slices are connected by screws.

[0006] Furthermore, the longitudinal cross-sections of the left and right convex plates are isosceles trapezoids, and several tower segments are enclosed to form a multi-sided pyramidal concrete tower segment. In two adjacent concrete tower segments, the upper surface of the lower concrete tower segment is consistent with the outer circumference length of the lower surface of the upper concrete tower segment, and multiple concrete tower segments are axially connected to form a concrete tower frame that gradually tightens from bottom to top.

[0007] Furthermore, an L-shaped bent plate and a matching screw sleeve are pre-embedded in the tower segment slice. A through hole is provided at one end of the bent plate exposed from the tower segment slice, and the screw is screwed into the screw sleeve of the adjacent tower segment slice through the through hole on the bent plate.

[0008] Furthermore, the steel-concrete composite tower also includes a transition section. The transition section is an integral hollow ring section with a cylindrical interior. The outer periphery of the transition section gradually changes from a polygon at the bottom to a circle. There is an annular depression on the upper surface of the transition section. The wall thickness of the transition section is greater than that of the steel tower and the concrete tower. The upper end anchor of the prestressed cable is fixed on the flange welded to the steel tower. The prestressed cable axially penetrates the annular wall of the transition section, extends inside the concrete tower, and is fixed on the ring beam through the lower end anchor.

[0009] Furthermore, the length of each piece of the tower section is 6 - 12 meters, and the width is 1 - 5 meters.

[0010] Furthermore, the adjacent concrete tower sections are connected by epoxy sealant with a thickness of 3 - 5 mm.

[0011] A construction method for a steel-concrete composite tower, which is used for the construction of the steel-concrete composite tower, includes the following steps:

[0012] Precasting tower section pieces and transition sections, transportation, assembling concrete tower sections, hoisting concrete tower sections and transition sections, threading prestressed cables, and hoisting the steel tower;

[0013] The specific steps for assembling the concrete tower sections are as follows: coat the contact parts between the tower section pieces with epoxy sealant, first pre-tighten the bent plate and the screw sleeve with a screw, when installing the last piece of each concrete tower section, first move the adjacent tower section pieces apart by a certain distance, and after installing the last piece of the tower section, tighten it to the correct position with a screw;

[0014] The specific steps for threading the prestressed cable are as follows: fix one end of the prestressed cable on the positioning tooling, lift the positioning tooling to the position of the transition section by a crane and fix it on the temporary lifting beam, manually guide the prestressed cable into the through hole of the transition section respectively, the lower end of the prestressed cable penetrates into the through hole of the ring beam, and is fixed with the lower end anchor.

[0015] Furthermore, the steel tower and the foundation can be produced on-site or prefabricated in a factory according to the actual working conditions.

[0016] Furthermore, the steel tower can be fabricated in sections.

[0017] The present invention has the following beneficial effects compared with the prior art:

[0018] (1) The tower section pieces are of a flat plate structure, and all tower section pieces can be produced with a mold with an adjustable width. They can be stacked for transportation, saving the mold production cycle and cost. The flat plate structure is easy to ensure the shape and position tolerances of the concrete precast parts, achieving high-precision parts.

[0019] (2) The left and right convex plates of the tower segment slices are offset by one plate thickness, which can be mutually inlaid and positioned, avoiding the through longitudinal seam of the tower. Moreover, when splicing, the splicing between the tower segment slices can be completed without precise alignment. Under the compressive state, the tower segment slices exert constraint forces on each other, improving the overall mechanical performance and stability of the tower;

[0020] (3) The tower segment slices exert constraint forces on each other, and the length of the concrete tower segment slices can be appropriately increased. The longitudinal length of the tower segment slices is 6 - 12 meters, which is more than twice the height of the conventional concrete tower segment, reducing the number of hoisting times.

[0021] (4) The tower segment slices are connected by embedding bent plates and screw sleeves. During construction, no scaffolding needs to be erected outside the tower segment. The bent plates are exposed, and the on-site installation is convenient and fast.

[0022] (5) The transition section is set with a gradually changing shape from bottom to top, solving the connection problem between the concrete tower and the steel tower. The upper surface of the transition section is provided with an annular depression adapted to the bottom flange of the steel tower, ensuring the connection effect between the transition section and the steel tower flange. The wall thickness of the transition section is greater than the thicknesses of the steel tower and the concrete tower. External prestressed cables are tensioned and anchored. The upper anchor of the prestressed cable directly acts on the welded flange at the bottom of the steel tower, with a simple structure and optimized mechanical performance.

[0023] (6) During the entire construction process, the prestressed cables are hoisted to the top of the concrete tower segment at one time using the crane for installing the mixed tower, reducing the construction period. No winch equipment is required, saving the upfront investment cost. Most of the construction is prefabricated, with less grouting operation, low segregation during high - altitude transportation, and convenient vibration, reducing the construction period. Description of the Drawings

[0024] Figure 1 is a schematic structural diagram of a steel - concrete composite tower according to the present invention.

[0025] Figure 2 is a longitudinal sectional view of the steel - concrete composite tower according to the present invention.

[0026] Figure 3 is Figure 2 an enlarged schematic view of the place B as described.

[0027] Figure 4 is Figure 2 an enlarged schematic view of the place A as described.

[0028] Figure 5 is a schematic structural diagram of the transition section according to the present invention.

[0029] Figure 6 is a schematic structural diagram of the tower segment slice according to the present invention.

[0030] Figure 7 It is a schematic structural diagram of the simplest tower segment sharding described in the present invention.

[0031] Figure 8 It is a schematic structural diagram of the concrete tower segment described in the present invention.

[0032] Figure 9 It is a schematic diagram of the connection relationship of the tower segment sharding described in the present invention.

[0033] Figure 10 It is a schematic diagram of being lifted by the prestressing cable described in the present invention.

[0034] In the figure, 1 is a steel tower; 11 is a flange; 2 is a transition section; 21 is a through hole; 3 is a concrete tower; 31 is a concrete tower segment; 311 is a left convex plate; 312 is a right convex plate; 313 is a bent plate; 314 is a screw sleeve; 315 is a screw rod; 4 is a foundation; 41 is a ring beam; 5 is a prestressing cable; 51 is an upper end anchor; 52 is a lower end anchor; 6 is a temporary lifting beam; 7 is a positioning tooling; 8 is a lifting rope; 81 is a lifting ring; 9 is an operation platform. Specific implementation manners

[0035] For a better understanding of the present invention, the present invention will be further described below with reference to the accompanying drawings.

[0036] As Figure 1-2 shown, a steel-concrete composite tower of the present invention includes a steel tower 1, a concrete tower 3, a transition section 2 and a foundation 4. The steel tower 1 is frustum-shaped or cylindrical and can be in multiple sections. The connection manner between the steel towers 1 is the prior art and will not be elaborated here. The concrete tower 3 is connected to the steel tower 1 through the transition section 2. The concrete tower 3 is axially connected by a plurality of concrete tower segments 31. The number of precast concrete tower segments 31 is determined according to the overall height of the wind turbine tower. The horizontal cross-section of the concrete tower segment 31 is a regular polygon. The concrete tower segment 31 is composed of a plurality of identical tower segment shards 311. The bottom concrete tower segment 31 is connected to the foundation 4.

[0037] As Figure 5 shown, the transition section 2 is an overall hollow ring section. The inside of the transition section 2 is cylindrical. The outer periphery of the transition section 2 gradually transitions from a polygon at the bottom to a circle at the top. The upper surface of the transition section 2 is provided with an annular depression adapted to the bottom flange 11 of the steel tower 1 to ensure the flange connection effect between the transition section 2 and the steel tower 1. A through hole 21 for the prestressing cable 5 to pass through is reserved along the axial direction of the transition section 2 in the annular depression of the transition section 2.

[0038] As Figure 3-4As shown in the figure, the steel tower 1 and the transition section 2 are connected together by external prestressed cables 5. The upper end anchor 51 of the prestressed cable is installed circumferentially on the flange 11 welded at the bottom section of the steel tower 1, and the lower end anchor 52 of the prestressed cable is installed on the hollow ring beam 41 on the foundation 4. The foundation 4 is a prior art and will not be elaborated here. The prestressed cable 5 axially penetrates the circumferential wall of the transition section 2 and is fixed on the lower surface of the ring beam 41 through the lower end anchor 52. The wall thickness of the transition section 2 is greater than the wall thicknesses of the steel tower 1 and the concrete tower 3, providing space for the prestressed cable 5 to pass through.

[0039] As Figure 6-8 shown, the tower segment piece as a whole is in a flat plate structure. The tower segment piece is composed of a left convex plate 311 and a right convex plate 312 connected in a staggered manner from top to bottom (the topmost one can be the left convex plate 311; it can also be the right convex plate 312, as Figure 6 shown). The number of the left convex plate and the right convex plate is at least 1 each. The left convex plate 311 and the right convex plate 312 are integrally formed, and a distance equal to the thickness of the tower segment piece is staggered left and right on the connection surface between the left convex plate 311 and the right convex plate 312. The longitudinal sections of the left convex plate 311 and the right convex plate 312 are isosceles trapezoids, and the lower base of the upper convex plate has the same length as the upper base of the adjacent lower convex plate; the horizontal section of the tower segment piece is an isosceles trapezoid, that is, both sides of the tower segment piece have an inclined angle in the vertical direction. A plurality of tower segment pieces enclose to form a concrete tower segment 31 in the shape of a frustum of a pyramid that narrows successively from bottom to top. The number of the enclosing tower segment pieces is different, and the base angle of the isosceles trapezoid of the horizontal section is different. Taking the number of tower segment pieces as 6 as an example, the base angle of the isosceles trapezoid of the horizontal section is 60 degrees.

[0040] In two adjacent concrete tower segments 31, the outer circumferential lengths of the upper surface of the lower concrete tower segment 31 and the lower surface of the upper concrete tower segment 31 are the same. A plurality of concrete tower segments 31 are connected in the axial direction to form a concrete tower 31 that narrows successively from bottom to top.

[0041] When the tower is subjected to longitudinal pressure, constraint forces are exerted on each other between the tower segment pieces. The misaligned tower segment pieces will provide an upward supporting force, and the pressure is converted into local shear stress, which can be offset by the concrete and steel materials. When the tower segment piece is subjected to a horizontal external force, the more misaligned surfaces there are, the horizontal friction force increases in multiples according to the number of misaligned surfaces, and the structure between adjacent tower segment pieces is more stable, improving the overall stress performance and stability of the tower. Therefore, the length of the concrete tower segment piece can be appropriately increased, and the preferred length is 6 - 12 meters, and the width is 1 - 5 meters.

[0042] As Figure 6 、 Figure 9As shown, it can be understood that the stress at the connecting corners of the tower segment is relatively concentrated, which is prone to rigid deformation and is a weak position of the mechanical component. In order to increase the local stiffness of this position, an L-shaped bent plate 313 is pre-embedded on the right side of the left convex plate 311 and the left side of the right convex plate 312, and a screw sleeve 314 is provided at the relative position of the left side of the left convex plate 311 and the right side of the right convex plate 312. A through hole is provided at the end of the bent plate 313 exposed from the tower segment. When splicing the tower segment, the screw 315 is screwed into the screw sleeve 314 through the through hole on the bent plate 313.

[0043] In order to enhance the strength of the tower segment to withstand wind force, a steel mesh is provided inside the tower segment (the steel mesh is not shown in the figure). One of the tower segment segments that make up the lowest concrete tower segment 3 has a door opening reserved for installing a tower maintenance door.

[0044] The present invention also provides a construction method of a steel-concrete composite tower, which is used for the construction of the above-mentioned steel-concrete composite tower, comprising:

[0045] Determine the specifications of the concrete tower based on the wind speed zone and wind turbine parameters at the construction site, including the height, wall thickness, vertical inclination angle, and trapezoidal base angle of the horizontal cross-section of the tower segments;

[0046] S1, prefabricate tower segments and transition sections, specifically the following steps: prefabricate tower segments in sections according to the determined parameters of the tower segments, use a mold with an open top and surrounding fences, place it horizontally on the pre-processed ground, place and tie the steel mesh and the embedded bent plate 313 and screw sleeve 314, cast the tower segments, and manually level the upper surface (inner surface of the tower frame) or smooth it with a template;

[0047] Remove the formwork, wait for the tower segments to solidify to a suitable hardness, mark the tower segments of the same concrete tower segment 31 with the same number, and lift them out of the mold position for curing;

[0048] Adjust the mold width according to the parameters to produce the tower segment of the next concrete tower segment 31;

[0049] The transition section 2 is manufactured while the tower section is being prefabricated. A through hole 21 is reserved on the transition section 2 for inserting the prestressed cable 5.

[0050] S2, transportation: transport the cured tower segments and transition section 2 to the construction site;

[0051] S3. Assemble the concrete tower segment 31. The specific steps are as follows: Coat the contact parts between the segment slices with epoxy sealant and assemble them in sequence. First, pre-tighten the embedded bent plate 313 and the embedded screw sleeve 314 with the screw 315. It should be noted that pre-tightening means screwing a part of the screw 315 into the screw sleeve, preferably screwing in 30% of the length of the screw 315. When installing the last segment slice of each concrete tower segment 31, first move the adjacent segment slices apart by a certain distance. After installing the last segment slice, tighten it to the correct position with the screw 315.

[0052] Assemble the other concrete tower segments 31 in sequence. The steps are the same as above. After assembly, level the upper surface and paste gaskets at 8 locations on the upper surface.

[0053] S4. Hoist the concrete tower segment: Install the lowermost concrete tower segment 31 on the concave pit on the upper surface of the reinforced concrete foundation 4. Pad it flat with a gasket before installation and grout it after installation. Hoist the assembled concrete tower segments 31 upward in sequence. For adjacent concrete tower segments 31, coat the upper surface of the lower concrete tower 31 with epoxy sealant. After hoisting in place, wait for a period of time for the epoxy adhesive to cure.

[0054] Hoist the transition section 2: Coat the lower surface of the transition section 2 with epoxy sealant and then hoist it onto the concrete tower segment 31. Pay attention to the flatness requirement when hoisting the transition section 2.

[0055] S5. Thread the prestressed cable 5. The specific steps are as follows: Place the positioning tooling 7 at the bottom of the tower. Pass the prestressed cable 5 through one end of the door opening and fix it on the positioning tooling 7, leaving the other end outside the tower. Number the prestressed cable 5 to prevent entanglement and fix the cable head at one end of the prestressed cable 5 on the positioning tooling 7. One end of the lifting rope 8 is pre-fixed on the positioning tooling 7, and the other end passes through the transition section 2 and is hung on the hook of the crane for lifting. Observe the lifting ring 81 on the perforated operation platform 9. After the lifting ring 81 passes over the temporary lifting beam 6, suspend the lifting, fix the lifting ring 81 on the temporary lifting beam 6 with a positioning pin, and the crane unhooks. Manually guide the prestressed cable 5 into the through hole 21 of the transition section 2 on the operation platform respectively. After the prestressed cable 5 is completely inserted into the through hole 21, the lower end of the prestressed cable 5 passes through the through hole of the ring beam 41 and is fixed with the lower end anchor 52.

[0056] Here it should be noted that the positioning tooling 7 includes a disc, and a plurality of clamps for fixing the prestressed cable 5 are arranged around the disc. The through hole 21 of the transition section 2 itself has a positioning center function, and the prestressed cable will not fall off from the through hole.

[0057] S6. Hoist the steel tower 1.

[0058] S7. Pass the prestressed cable 5 through the steel tower 1 and fix it on the top surface of the flange of the steel tower 1 with the upper end anchor 51. Remove the positioning tooling 7, and the tower construction is completed.

[0059] The construction method described in the present invention hoists the prestressed cable to the predetermined position at one time, reducing the construction period. Moreover, during the hoisting process, only a crane and positioning tooling are required, without the need for a hoisting equipment, saving the investment cost.

[0060] Specifically, for the convenience of construction, the steel tower can be fabricated in sections. Dividing the relatively tall tower into multiple sections can reduce the construction difficulty caused by the excessive height of the tower.

[0061] Specifically, the steel tower and the foundation can be produced on-site or prefabricated in a factory according to the actual working conditions.

[0062] A steel-concrete composite tower and its construction method proposed by the present invention can achieve a fully prefabricated construction of factory prefabrication and on-site assembly, and has a short construction period, high mechanical properties and good stability.

[0063] The above are only the preferred implementation schemes of the present invention, but the present invention is not limited to the above specific implementation schemes. Without departing from the principle of the present invention, those of ordinary skill in the art can make several modifications, supplements or use similar methods for substitution, which should also be regarded as the protection scope of the present invention.

Claims

1. A steel-concrete composite tower, comprising a steel tower (1), a concrete tower (3) and a foundation (4), wherein the concrete tower (3) is composed of multiple concrete tower segments (31), and is characterized in that, The concrete tower segment (31) is formed by enclosing multiple identical flat tower segment slices with each other. The flat tower segment slices are composed of left convex plates (311) and right convex plates (312) that are staggered from top to bottom. The contact surfaces of the left convex plate (311) and the right convex plate (312) are offset by a distance equal to the thickness of one tower segment slice from left to right, and the tower segment slices are connected by bolts. The longitudinal sections of the left convex plate (311) and the right convex plate (312) are isosceles trapezoids, and the lower base of the upper convex plate has the same length as the upper base of the adjacent lower convex plate; several tower segment slices enclose to form a multi-prism-shaped concrete tower segment (31). Among two adjacent concrete tower segments (31), the outer peripheral length of the upper surface of the lower concrete tower segment (31) is the same as that of the lower surface of the upper concrete tower segment (31). Multiple concrete tower segments (31) are axially connected to form a concrete tower frame that gradually narrows from bottom to top. It further includes a transition section (2). The transition section (2) is an integral hollow ring section. The inside of the transition section (2) is cylindrical. The outer periphery of the transition section (2) gradually transitions from a polygon at the bottom to a circle at the top. An annular depression for the flange (11) at the bottom end of the steel tower frame (1) to sit in is provided on the upper surface of the transition section (2). The concrete tower frame (3) is connected to the steel tower frame (1) through the transition section (2). An L-shaped bent plate (313) and a matching stud (314) are pre-embedded in the tower segment slice. One end of the bent plate (313) exposed from the tower segment slice is provided with a through hole, and a screw (315) is screwed into the stud (314) of the adjacent tower segment slice through the through hole on the bent plate (313).

2. The steel-concrete composite tower according to claim 1, wherein, The wall thickness of the transition section (2) is greater than the wall thicknesses of the steel tower frame (1) and the concrete tower frame (3). The upper end anchor (51) of the prestressed cable (5) is fixed on the flange (11) welded to the steel tower frame (1). The prestressed cable (5) axially penetrates the annular wall of the transition section (2) and is fixed on the lower surface of the ring beam (41) through the lower end anchor (52).

3. The steel-concrete composite tower according to claim 1 or 2, characterized in that, The length of the tower segment slice is 6 - 12 meters, and the width is 1 - 5 meters.

4. The steel-concrete composite tower according to claim 1 or 2, characterized in that, The adjacent concrete tower segments (31) are connected using an epoxy sealant with a thickness of 3 - 5 millimeters.

5. A construction method for a steel-concrete composite tower frame, used for the construction of the steel-concrete composite tower frame according to any one of claims 1 - 4, includes the following steps: Precast tower segment slices and the transition section (2), transportation, assembly of the concrete tower segment (31), hoisting of the concrete tower segment (31) and the transition section (2), threading of the prestressed cable (5), hoisting of the steel tower frame (1); The specific steps for assembling the concrete tower segment (31) are: coat the contact parts between the tower segment slices with epoxy sealant, first pre-tighten the bent plate (313) and the stud (314) with the screw (315). When installing the last tower segment slice of each concrete tower segment (31), first move the adjacent tower segment slices away by a certain distance. After installing the last tower segment slice, tighten it to the correct position with the screw (315). The specific steps for threading the prestressed cable (5) are as follows: Fix one end of the prestressed cable (5) on the positioning tooling (7), lift the positioning tooling (7) to the position of the transition section (2) and fix it on the temporary lifting beam (6). Manually guide the prestressed cable (5) to extend into the through hole (21) of the transition section respectively. The lower end of the prestressed cable (5) penetrates into the through hole of the ring beam (41) and is fixed with the lower end anchor (52).

6. According to the construction method of the steel-concrete composite tower described in claim 5, the steel tower and the foundation are produced on site or prefabricated in the factory according to the actual working conditions.

7. According to the construction method of the steel-concrete composite tower described in claim 5, the steel tower is fabricated in sections.

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