A design method for prefabricated mixed tower with pieces considering the universality of molds

Abstract

The present invention provides a piecewise prefabricated mixed tower design method considering the universality of molds, including: according to basic conditions such as unit parameters, hoisting equipment, load level, etc., whether the bearing capacity of each section, tower frequency and blade clearance meet the design requirements is used as a criterion to determine the mixed tower body type and mold system of the reference project; compare the unit parameters and wind turbine loads of the new project and the reference project, and ensure that the taper is consistent by increasing (or decreasing) several sections of concrete tower segments downward (or upward) to ensure that most of the middle tower segments remain unchanged, so as to achieve the purpose of universal mold design, and achieve the economic optimization effect of the design scheme by fine-tuning the concrete strength grade, the number of prestressed tendons, etc. The present invention can adapt to the design requirements of wind turbines with different heights and different load levels, and the design is efficient and cost-saving. It is a better technical solution for the universal design of prefabricated mixed towers.

Description

Technical Field

[0001] The present invention belongs to the technical field of onshore wind power concrete towers, and in particular relates to a design method for a piecewise prefabricated assembled mixed tower taking into account the versatility of molds. Background Art

[0002] With the further development and utilization of wind resources in my country, wind turbines are gradually developing towards high power and high altitude. Traditional all-steel tower technology can hardly meet the demand for high rigidity and large diameter wind turbine towers. In recent years, prefabricated and assembled hybrid towers have received extensive attention in the field of wind power. This structure uses a concrete tower at the bottom and a conventional steel tower at the top. It has the rigidity advantages of a concrete tower and the rapid construction advantages of a steel tower. It can effectively make up for the shortcomings of low rigidity and small diameter of flexible steel towers and has the advantage of developing towards high altitude.

[0003] The concrete tower at the lower part of the mixed tower is composed of several hollow frustum-shaped prefabricated tower sections connected vertically, and the segmentation method is horizontal segmentation; each tower section is composed of multiple arc-shaped prefabricated concrete segments connected in a circular manner, and the segmentation method is vertical segmentation.

[0004] One of the main structural types of common concrete towers is the cone type. The diameter of each section of the cone tower decreases from bottom to top, which can ensure that the bearing capacity of each section elevation of the concrete tower changes evenly and is not prone to stress concentration. However, because the sizes of each section of this tower type are different, more molds need to be customized before concrete prefabrication production, and high-precision molds are expensive, which has a certain impact on construction efficiency and cost. Therefore, how to reasonably design the tower segments and sizes to ensure the versatility of the molds and control the production cycle and investment cost of the concrete tower will become a new challenge and problem that the prefabricated assembled hybrid tower technology in the wind power industry will face in the future. Summary of the invention

[0005] The purpose of the present invention is to provide a design method for a prefabricated concrete tower in sections to solve the above problems, propose an innovative design process, realize the universality of concrete tower molds, and achieve the purpose of economic efficiency; the design method can meet the design requirements of towers of different heights and adapt to wind turbines with different load levels and single-unit capacities. The present invention adopts the following technical solutions:

[0006] The controlling design factors of the segmented prefabricated assembled hybrid tower design method are tower size, concrete strength, prestressed tendon tension value, tower frequency and wind turbine clearance.

[0007] A method for designing a prefabricated mixed tower in pieces taking into account the universality of molds, characterized in that it comprises the following steps:

[0008] (1) Based on the unit parameters and hoisting equipment conditions of the reference project, preliminarily determine the height ratio of the concrete tower section to the steel tower section, and assume an initial concrete tower taper value;

[0009] (2) According to the load level at the bottom of the tower of the reference project, select the appropriate concrete strength grade and prestressed tendon tension value, and calculate and determine the outer diameter, inner diameter and wall thickness of the bottom section of the concrete tower section;

[0010] (3) According to the height, taper and bottom cross-sectional dimensions of the concrete tower section, the cross-sectional dimensions of the selected concrete tower sections at different elevations are calculated to determine the preliminary shape of the concrete tower;

[0011] (4) For the initially determined concrete tower body shape, the cross-sectional bearing capacity verification analysis is performed; if the design indicators of the cross-sections of the concrete tower meet the design requirements and the safety redundancy is equivalent, then step (5) is performed; if the design indicators of the cross-sections of the concrete tower do not meet the design requirements or the safety redundancy is greatly different, then the process returns to step (1) to adjust the tower body parameters, including the taper and cross-sectional size of the concrete tower;

[0012] (5) After the shape of the concrete tower section is determined, the cross-sectional diameters of the steel conversion section and the selected steel tower sections at different elevations are determined based on the cross-sectional dimensions of the top of the concrete tower section and the difference in the dimensions of the fan interface flange, and the thickness of the steel plate is determined based on the bearing capacity calculation;

[0013] (6) After the dimensions of the concrete tower section and the steel tower section are determined, it is necessary to check whether the frequency of the concrete tower and the blade clearance meet the design requirements of the wind turbine to avoid the risk of resonance between the concrete tower and the wind turbine or tower sweeping. If the frequency and clearance meet the design requirements, proceed to step (7); if not, return to step (1) and adjust the tower body parameters, including the concrete tower height, taper, and cross-sectional dimensions.

[0014] (7) To meet the normal road transportation requirements of the concrete tower, the concrete tower sections are cut into sections and slices, and the sizes of each section and slice are determined;

[0015] (8) Designing a complete set of molds for the concrete tower according to the sizes of the concrete tower sections and slices; by equally dividing each section into a number of slices, several slices of the same section can share the same mold;

[0016] (9) Considering the universality of molds between different projects, different models, and different hub heights, for the design of new projects, the unit parameters and wind turbine loads of the new projects are compared and analyzed with those of the reference projects;

[0017] (10) When the wind turbine load of the new project is significantly larger or smaller than that of the reference project, while keeping the tower cone angle unchanged, the concrete tower sections are extended or reduced up and down to meet the load-bearing capacity requirements, so as to realize the rapid design of the hybrid tower shape; that is: if the wind turbine load of the new project is large, appropriately increase the concrete tower sections at the lower part of the tower; if the wind turbine load of the new project is small, appropriately reduce the concrete tower sections at the lower part of the tower, and appropriately increase, keep unchanged or reduce the concrete tower sections at the upper part according to the load-bearing capacity of the steel tower and the capacity of the hoisting equipment;

[0018] (11) After the hybrid tower shape of the new project is determined, according to the redundancy of the tower structure load-bearing capacity, by appropriately adjusting the concrete strength and the prestressed tendon tension value within a certain range, the cross-section design indexes of each section interface of the concrete tower can meet the design requirements, and the economic optimization effect of the design scheme can be achieved;

[0019] (12) According to the increase or decrease of the concrete tower sections of the new project, design the molds for a small number of newly added tower sections to realize the universality of most molds.

[0020] Further, the design indexes described in the above step (4) include but are not limited to: the flexural bearing capacity of each cross-section, the anti-overturning stability, the vertical bearing capacity, the horizontal shear resistance, the crack width, the fatigue stress level, etc.

[0021] Further, wet grouting connection or dry bolt assembly connection can be adopted between each section and each piece in the above step (7).

[0022] Further, the different elevations referred to in steps (3) and (4) are the elevations corresponding to the interfaces of each section of the concrete tower section.

[0023] Further, the different elevations referred to in step (5) are the elevations corresponding to the interfaces of the steel conversion section and each section of the steel tower section.

[0024] Further, except for extending or reducing the concrete tower sections, other concrete tower sections use the molds described in step (8).

[0025] According to the second aspect of the purpose of the present invention, the present invention provides a non-transitory computer-readable storage medium, on which a computer program is stored, characterized in that when the computer program is executed by a processor, the steps of the above-mentioned segmented precast and assembled hybrid tower design method considering the universality of the mold are realized.

[0026] According to a third aspect of the purpose of the present invention, the present invention provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the above-mentioned method for designing a piecewise prefabricated assembled mixed tower taking into account the universality of molds when executing the program.

[0027] The present invention provides a prefabricated and assembled mixed tower design method, which is convenient for new projects to be designed quickly and efficiently and maximizes the use of molds of reference projects. Furthermore, the scheme of the present invention is highly flexible. Under the premise of keeping the tower taper unchanged, by increasing (or decreasing) the number of concrete tower segments downward (or upward), most of the middle tower segments are ensured to remain unchanged, and universal adaptation to wind turbines with different unit capacities, hub heights, and wind turbine loads is achieved, thereby ensuring the versatility of the tower mold and achieving the purpose of efficient design.

[0028] Furthermore, by utilizing universal segment molds to produce pipe segments, the present invention can reduce the number of newly opened molds and significantly shorten the mold production cycle, which is beneficial to shortening the production period of concrete tower pipe segments and saving mold production costs, thereby achieving the purpose of reducing costs and increasing efficiency.

[0029] The technical solution of the present invention not only takes into account the versatility of the mold, but also can achieve the economic optimization effect of the design solution by fine-tuning the concrete strength grade, the number of prestressed tendons, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The present invention discloses a prefabricated assembled mixing tower design flow chart.

[0031] Figure 2 It is a comparison diagram of the overall sections of the prefabricated assembled mixing tower of a new project designed by the design method of the present invention and a reference project in an embodiment of the present invention.

[0032] Figure 3 It is a schematic diagram of the segmentation, segmentation and splicing of the concrete tower in an embodiment of the present invention. DETAILED DESCRIPTION

[0033] The reference project and the new project of this embodiment are both steel-concrete combined towers with a hub height of 150m. The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0034] like Figure 2As shown, a prefabricated and assembled mixed tower is a concrete-steel composite structure. Taking the reference project tower as an example, it includes a top steel tower 101, a steel transition section 102, a concrete tower 103, a bottom hollow fan foundation 104 and a prestressed steel strand system 105 from top to bottom. The concrete tower 103 is a conical cylinder, and each section is designed to be 3.0m high. The steel tower 101 is connected to the steel-concrete transition section 102 by a high-strength bolt assembly, and the steel-concrete transition section 102, the concrete tower 103 and the hollow fan foundation 104 are integrally connected by a prestressed steel strand system 105 to improve the overall bending resistance of the tower.

[0035] like Figure 1 As shown, the present invention provides a design method for a prefabricated mixed tower taking into account the universality of molds, and the design method comprises the following steps:

[0036] (1) Based on the unit parameters and hoisting equipment conditions of the reference project, it is preliminarily determined that the height of the concrete tower section 103 is 99m, the height of the steel tower 101 and the steel conversion section 102 is about 50m, and it is assumed that the initial taper value of the concrete tower 103 is 0.0175.

[0037] (2) According to the load level at the bottom of the tower of the reference project, the concrete tower 103 is made of concrete with a strength of C60, and 24 bundles (15 strands in each bundle) of prestressed steel strands 105 are used. The upper end is anchored to the anchor flange plate of the steel-concrete transition section 102, and the lower end is anchored to the bottom surface of the fan foundation 104. The prestressed steel strands 105 are arranged at an interval of 15° in the annular direction. The calculation results show that the outer diameter of the bottom cross section of the concrete tower section 103 is 7600 mm, the inner diameter is 6800 mm, and the wall thickness is 400 mm.

[0038] (3) According to the height, taper and bottom cross-sectional dimensions of the concrete tower section 103, the cross-sectional dimensions of each elevation are calculated to determine the preliminary shape of the concrete tower 103. In this embodiment, except for the door opening section, the outer diameter and inner diameter of the cross-sectional area of ​​the concrete tower section 103 vary uniformly from bottom to top between 7500mm and 4100mm and 6700mm and 3300mm, respectively, and the wall thickness of each section is 400mm. The elevations preferably use the elevations corresponding to the interfaces of the various sections of the concrete tower section, so that the upper and lower cross-sectional dimensions of each section can be determined preferentially, and the mold dimensions of each section can be determined quickly and conveniently. The various sections of the concrete tower section refer to the various sections of the concrete tower section determined before the calculation step of the starting step (3).

[0039] (4) For the initially determined concrete tower 103 body shape, the bearing capacity of each section is checked and analyzed; and the bending bearing capacity, anti-overturning stability, vertical bearing capacity, horizontal shear bearing capacity, crack width, and fatigue stress level of each section are used as design indicators. It is empirically calculated that the design indicators of each section of the concrete tower 103 in this embodiment meet the design requirements and the safety redundancy is equivalent. It should be noted that if the design indicators of each section of the concrete tower 103 do not meet the design requirements or the safety redundancy is greatly different, return to step (1) and adjust the tower body parameters, including the taper and cross-sectional size of the concrete tower 103.

[0040] (5) After the shape of the concrete tower section 103 is determined, the diameters of the steel conversion section 102 and each section of the steel tower section 101 are determined according to the difference between the top section size of the concrete tower section 103 and the size of the fan interface flange, and the wall thickness of the steel plate is determined according to the bearing capacity calculation. The sections of the steel tower section 101 are preferably the interfaces of each segment of the steel tower section, so that the upper and lower section sizes of each segment can be determined preferentially, and the cutting size of the steel plate of each segment can be determined quickly and conveniently. The segments of the steel tower section refer to the segments of the steel tower section determined before the calculation step of step (3) is started.

[0041] (6) After the dimensions of the concrete tower section 103 and the steel tower section 101 are determined, the tower frequency and blade clearance are checked to see whether they meet the design requirements of the wind turbine to avoid the risk of resonance between the tower and the wind turbine or tower sweep. After verification, the tower frequency and clearance in this embodiment meet the design requirements. If not, return to step (1) to adjust the tower body parameters, including the height, taper, and cross-sectional dimensions of the concrete tower 103.

[0042] (7) In order to meet the normal road transportation requirements of the concrete tower 103, the concrete tower section 103 is designed in sections and pieces, and the size of each section and piece is determined; each section and piece can be connected by grouting steel bars or bolt assemblies. Figure 3 As shown, in this embodiment, the 99m high concrete tower 103 is divided into 33 sections, each with a height of 3m. Each section 107 is composed of 4 pieces of quarter prefabricated segments 108 of the same size, which are spliced ​​in a circumferential direction. The sizes of all segments 108 meet the normal road transportation requirements, and there is no over-width, over-height, or large component transportation. As a preferred solution, the prefabricated segments 108 are connected to form a complete ring through structural adhesive 109 and bent bolts 110, and the upper and lower sections of the concrete tower segments 107 are staggered after the installation position is determined by positioning pins 111.

[0043] (8) According to the size of the concrete tower tube 103 segments and pieces, a complete set of molds for the concrete tower tube 103 is designed, including an inner mold 112, an outer mold 113 and a side mold 114, such as Figure 3As shown; in this embodiment, by dividing each segment into four equal pieces 108, several pieces of the same segment can share the same mold.

[0044] (9) Considering the universality of molds between different projects, for the design of new projects, the unit parameters and fan loads of the new projects are compared and analyzed with those of the reference projects.

[0045] (10) According to calculation, the wind turbine load of the new project in this embodiment is larger than that of the reference project. Under the condition of ensuring that the taper remains unchanged, 4 sections of concrete tower barrel sections (excluding the doorway section and the topmost section) are added at the bottom and reduced at the top to meet the bearing capacity requirements, thereby realizing the rapid design of the mixed tower body. After the preliminary tower body design, the bottom section of the concrete tower barrel section 106 of the new project has an outer diameter of 8100mm, an inner diameter of 7300mm, and a wall thickness of 400mm. The outer diameter and inner diameter of each elevation section from the second to the 33rd section decrease between 8000mm and 4600mm and 7200mm and 3800mm, respectively, and the wall thickness of each section is 400mm.

[0046] (11) In this embodiment, after adding four sections at the bottom and reducing four sections at the top, the redundancy of the structural bearing capacity of the concrete tower 106 of the new project is relatively small. By appropriately adjusting the concrete strength (C65) and the number of prestressed tendons (24 bundles, 17 tendons in each bundle) within a certain range, it can be achieved that the design indicators of each section of the concrete tower 106 meet the design requirements.

[0047] (12) To achieve mold universality, in this embodiment, the cross-sectional dimensions of sections 2 to 28 of the concrete tower 103 of the reference project are completely consistent with sections 6 to 32 of the concrete tower 106 of the new project. The mold of the reference project can be used to cast and produce the universal section located in the middle of the concrete tower 106 of the new project, so as to save costs and shorten the construction period. In addition, molds for a small number of newly added tower sections (sections 1 to 5 and section 33) are designed based on the increase or decrease in the concrete tower sections of the new project.

[0048] Through the description of the above embodiments, it can be clearly understood by those skilled in the art that the facilities of the present invention can be implemented by means of software plus the necessary general hardware platform. The embodiments of the present invention can be implemented using an existing processor, or by a dedicated processor used for this purpose or other purposes for an appropriate system, or by a hard-wired system. The embodiments of the present invention also include a non-transitory computer-readable storage medium, which includes a machine-readable medium for carrying or having a machine-executable instruction or data structure stored thereon; such a machine-readable medium can be any available medium that can be accessed by a general or special-purpose computer or other machine with a processor. For example, such a machine-readable medium can include RAM, ROM, EPROM, EEPROM, CD-ROM or other optical disk storage, disk storage or other magnetic storage device, or any other medium that can be used to carry or store the required program code in the form of machine-executable instructions or data structures, and can be accessed by a general or special-purpose computer or other machine with a processor. When information is transmitted or provided to a machine via a network or other communication connection (hard-wired, wireless, or a combination of hard-wired or wireless), the connection is also considered a machine-readable medium.

[0049] The above embodiment is only a preferred technical solution of the present invention. Those skilled in the art should understand that the technical solutions or parameters in the embodiments can be modified or replaced without departing from the principle and essence of the present invention, and all should be covered within the protection scope of the present invention.

Claims

1. A design method for prefabricated mixed towers taking into account the universality of molds. Features: The following steps are involved: (1) Based on the unit parameters and hoisting equipment conditions of the reference project, preliminarily determine the height ratio of the concrete tower section to the steel tower section, and assume an initial concrete tower taper value; (2) According to the load level at the bottom of the tower of the reference project, select the appropriate concrete strength grade and prestressed tendon tension value, and calculate and determine the outer diameter, inner diameter and wall thickness of the bottom section of the concrete tower section; (3) According to the height, taper and bottom cross-sectional dimensions of the concrete tower section, the cross-sectional dimensions of the selected concrete tower sections at different elevations are calculated to determine the preliminary shape of the concrete tower; (4) For the initially determined concrete tower body shape, the cross-sectional bearing capacity verification analysis is performed; if the design indicators of the cross-sections of the concrete tower meet the design requirements and the safety redundancy is equivalent, then step (5) is performed; if the design indicators of the cross-sections of the concrete tower do not meet the design requirements or the safety redundancy is greatly different, then the process returns to step (1) to adjust the tower body parameters, including the taper and cross-sectional size of the concrete tower; (5) After the shape of the concrete tower section is determined, the cross-sectional diameters of the steel conversion section and the selected steel tower sections at different elevations are determined based on the cross-sectional dimensions of the top of the concrete tower section and the difference in the dimensions of the fan interface flange, and the thickness of the steel plate is determined based on the bearing capacity calculation; (6) After the dimensions of the concrete tower section and the steel tower section are determined, it is necessary to check whether the frequency of the concrete tower and the blade clearance meet the design requirements of the wind turbine to avoid the risk of resonance between the concrete tower and the wind turbine or tower sweeping. If the frequency and clearance meet the design requirements, proceed to step (7); if not, return to step (1) and adjust the tower body parameters, including the concrete tower height, taper, and cross-sectional dimensions. (7) To meet the normal road transportation requirements of the concrete tower, the concrete tower sections are cut into sections and slices, and the sizes of each section and slice are determined; (8) Designing a complete set of molds for the concrete tower according to the sizes of the concrete tower sections and slices; by equally dividing each section into a number of slices, several slices of the same section can share the same mold; (9) Considering the universality of molds between different projects, different models, and different hub heights, for the design of new projects, the unit parameters and wind turbine loads of the new projects are compared and analyzed with those of the reference projects; (10) When the wind turbine load of the new project is larger or smaller than that of the reference project, the concrete tower segments are extended or reduced up and down to meet the load-bearing capacity requirements while ensuring that the tower taper remains unchanged, thereby achieving rapid design of the mixed tower body; that is, if the wind turbine load of the new project is larger, the concrete tower segments are appropriately increased at the bottom of the tower; if the wind turbine load of the new project is smaller, the concrete tower segments are appropriately reduced at the bottom of the tower, and the concrete tower segments at the top are appropriately increased, kept unchanged, or reduced according to the load-bearing capacity of the steel tower and the capacity of the lifting equipment; (11) After the new project concrete tower is determined, the concrete strength and prestressed tendon tension value are appropriately adjusted within a certain range according to the redundancy of the tower structure's bearing capacity, so that the cross-sectional design indicators of each segment interface of the concrete tower meet the design requirements and achieve the economic optimization effect of the design scheme; (12) Based on the increase or decrease of concrete tower segments in the new project, a small number of newly added tower segment molds are designed to achieve the universality of most molds.

2. According to the design method of a prefabricated mixed tower in pieces taking into account the versatility of molds according to claim 1, Features: The design indicators described in the above step (4) include: bending bearing capacity of each section, anti-overturning stability, vertical bearing capacity, horizontal shear bearing capacity, crack width, and fatigue stress level.

3. According to the design method of a prefabricated mixed tower in pieces taking into account the versatility of molds according to claim 1, Features: In the above step (7), each segment or slice is connected by wet grouting or dry bolt assembly.

4. According to claim 1, a method for designing a prefabricated mixed tower in pieces taking into account the versatility of molds, Features: The different elevations referred to in steps (3) and (4) are the elevations corresponding to the interfaces of the various sections of the concrete tower segment.

5. According to the design method of a prefabricated mixed tower in pieces taking into account the versatility of molds according to claim 1, Features: The different elevations referred to in step (5) are the elevations corresponding to the interfaces of the steel transition sections and the interfaces of the various sections of the steel tower sections.

6. According to claim 1, a method for designing a prefabricated mixed tower in pieces taking into account the versatility of molds, Features: In addition to extending or reducing the concrete tower segment, other concrete tower sections use the mold described in step (8).

7. A non-transitory computer-readable storage medium having a computer program stored thereon, It is characterized in that When the computer program is executed by a processor, the steps of the method for designing a piecewise prefabricated assembled mixing tower taking into account the versatility of molds as described in any one of claims 1 to 6 are implemented.

8. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, It is characterized in that When the processor executes the program, the steps of the method for designing a piecewise prefabricated assembled mixing tower taking into account the versatility of molds as described in any one of claims 1 to 7 are implemented.

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