Design method for bottom plate thickness of the twelve - earth - spiral tower foot structure based on the coupling effect of tension and shear

Abstract

The present invention provides a method for designing the thickness of the bottom plate of a twelve-earth-screw tower foot structure based on the tension-shear coupling effect, including the following steps: According to the distribution of the uplift loads borne by the outer and inner earth screws inside and outside the assembly area, using the uneven distribution ratio coefficient of the outer and inner earth screws, calculate the internal force of the outer earth screws; establish the relationship between the bottom plate thickness and the internal force of the outer earth screws under the action of only the uplift load; perform stress conversion on the established relationship between the bottom plate thickness and the internal force of the outer earth screws to obtain the expression of the uplift stress borne by the bottom plate; consider the shear effect of the main material on the bottom plate during uplift and calculate the shear stress generated by the shear effect; according to the design strength of the bottom plate should meet the tension-shear coupling effect generated after the coupling of the uplift stress and the shear stress, solve the minimum thickness of the bottom plate of the twelve-earth-screw tower foot structure. Ensure that the design strength of the bottom plate under the tension-shear coupling action is sufficient, the design result meets the actual operation requirements, and improve the safety and economy of the power transmission system.

Description

Technical Field

[0001] The present invention relates to the technical field of the design of tower foot joints of transmission lines. Specifically, it relates to a design method for the thickness of the bottom plate of a twelve - earth - screw tower foot structure based on the tensile - shear coupling effect. Background Art

[0002] With the continuous increase in the voltage level of transmission lines, the load level of transmission towers is also increasing rapidly. This leads to an increasing demand for the bearing capacity of the foundation connection joints of transmission towers. The traditional eight - earth - screw connection joints can no longer meet the requirements of large loads, and thus a new type of twelve - earth - screw connection joints are needed to meet the bearing capacity requirements.

[0003] Among them, in the Chinese invention patent with the application number 2022115899274, an embedded twelve - earth - screw tower foot structure and its uplift design method are proposed. The embedded twelve - earth - screw has good force - bearing uniformity, high bearing capacity, and good economy, and is the first choice for the twelve - earth - screw joint structure. However, there are currently no corresponding provisions and design methods in the codes and related literature. In engineering design, the empirical construction method is generally used for design, which is likely to result in a situation where the designed thickness of the bottom plate cannot meet the actual thickness requirements, leading to a reduction in transmission reliability; or a situation where the designed thickness of the bottom plate exceeds the actual thickness requirements, resulting in poor transmission economy. Although an uplift design method is given in the above - mentioned patent, the tensile - shear coupling effect borne by the bottom plate is not comprehensively considered, and the obtained design result is not accurate enough, and its reliability and advancement are relatively low, with large limitations, which is not conducive to the development of the transmission line structure theory. Summary of the Invention

[0004] The present invention aims to at least solve one of the technical problems existing in the prior art, such as the lack of a design method for the embedded twelve - earth - screw tower foot structure, using the empirical construction method for design, which is likely to result in a situation where the designed thickness of the bottom plate cannot meet the actual thickness requirements, leading to a reduction in transmission reliability; or a situation where the designed thickness of the bottom plate exceeds the actual thickness requirements, resulting in poor transmission economy; other design methods do not comprehensively consider the tensile - shear coupling effect borne by the bottom plate, and the obtained design result is not accurate enough, with low reliability and advancement.

[0005] Therefore, the present invention provides a design method for the thickness of the bottom plate of a twelve - earth - screw tower foot structure based on the tensile - shear coupling effect.

[0006] The present invention provides a method for designing the thickness of the bottom plate of a twelve - earth - screw tower - foot structure based on the tension - shear coupling effect. The twelve - earth - screw tower - foot structure includes: a main material, earth screws, a bottom plate, a main shoe plate, and a secondary shoe plate; the bottom plate is fixedly installed on the ground through the earth screws, the main shoe plate is in a cross - shaped structure, the cross - shaped structure is symmetrically arranged on the bottom plate, the secondary shoe plate is vertically arranged at the end of the main shoe plate, and the main material is fixedly connected to the main shoe plate through bolts; the cross - shaped structure of the main shoe plate divides the bottom plate into four assembly areas, the earth screws are divided into four groups, each group of earth screws includes two outer earth screws and one inner earth screw, and the inner earth screw is arranged on the side of the outer earth screw closer to the center of the bottom plate; one group of earth screws is arranged in each area, and the four groups of earth screws are centrosymmetrically arranged with the center of the main shoe plate as the center and axially symmetrically arranged with the main shoe plate as the axis; it is characterized by the following steps:

[0007] S1. According to the distribution of the uplift loads borne by the outer and inner earth screws in the assembly area, using the non - uniform distribution ratio coefficient of the outer and inner earth screws, calculate the internal force of the outer earth screws.

[0008] S2. Establish the relationship between the thickness of the bottom plate and the internal force of the outer earth screws only under the action of the uplift load.

[0009] S3. Perform stress conversion on the relationship between the thickness of the bottom plate and the internal force of the outer earth screws established in S2 to obtain the expression of the uplift stress borne by the bottom plate.

[0010] S4. Considering the shear effect of the main material on the bottom plate during uplift, calculate the shear stress generated by the shear effect.

[0011] S5. According to the design strength of the bottom plate, which should satisfy the tension - shear coupling effect generated by the coupling of the uplift stress in S3 and the shear stress in S4, solve for the minimum thickness of the bottom plate of the twelve - earth - screw tower - foot structure.

[0012] According to the method for designing the thickness of the bottom plate of the twelve - earth - screw tower - foot structure based on the tension - shear coupling effect in the above technical solution of the present invention, the following additional technical features may also be provided:

[0013] In the above technical solution, in S1, in the assembly area, the distribution of the uplift loads borne by the outer and inner earth screws is as follows:

[0014]

[0015] Among them, is the internal force of the outer earth screw under the action of the uplift load, is the internal force of the inner earth screw under the action of the uplift load, and T is the load effect of the bottom plate.

[0016] In the above technical solution, the calculation method of the internal force of the outer earth screw is:

[0017]

[0018] Among them, is the uneven distribution ratio coefficient of the inner and outer ground screws.

[0019] In the above technical solution, the calculation method of the uneven distribution ratio coefficient of the inner and outer ground screws is as follows:

[0020]

[0021] Among them, is the vertical distance from the center of the inner ground screw to the center of the shoe plate; is the vertical distance from the center of the outer ground screw to the center of the shoe plate.

[0022] In the above technical solution, in S2, under the action of the uplift load only, the relationship between the bottom plate thickness and the inner force of the outer ground screw is:

[0023]

[0024] Among them, is the bottom plate thickness; is the vertical distance between the centers of two outer ground screws in the same assembly area; is the vertical distance from the center of the outer ground screw to the edge of the bottom plate; is the length of the secondary shoe plate in the assembly area; is the yield strength of the bottom plate.

[0025] In the above technical solution, in S3, the stress conversion of the relationship between the bottom plate thickness and the inner force of the outer ground screw established in S2 is carried out, and the expression of the uplift stress borne by the bottom plate is as follows:

[0026] .

[0027] In the above technical solution, in S4, considering the shear effect of the main material on the bottom plate during uplift, the calculation method of the shear stress is as follows:

[0028]

[0029] Among them, is the thickness of the main shoe plate; is the shear design strength of the bottom plate steel; B is the width of the bottom plate; is the horizontal shear load borne by the bottom plate in the X direction during uplift; is the horizontal shear load borne by the bottom plate in the Y direction during uplift.

[0030] In the above technical solution, in S5, in order to ensure the design strength of the bottom plate under the combined action of tension and shear, the uplift stress and shear stress of the bottom plate should meet the following requirements:

[0031]

[0032] Among them, is the partial factor of safety for steel.

[0033] In the above technical solution, the calculation method for the minimum thickness of the bottom plate of the twelve - earth - screw tower foot structure is:

[0034] .

[0035] In any of the above technical solutions, when calculating the minimum thickness of the bottom plate of the twelve - earth - screw tower foot structure in S5, the yield - line theory floating coefficient also needs to be superimposed, and the value of the yield - line theory floating coefficient is not less than 1.1.

[0036] In summary, due to the adoption of the above technical features, the beneficial effects of the present invention are:

[0037] Fully consider the tensile - shear coupling effect borne by the bottom plate, consider the uneven distribution of internal forces of the internal earth screws and external earth screws in the assembly area, and simplify the calculation of the uneven distribution ratio coefficient, ensure that the design strength of the bottom plate under the tensile - shear coupling action is sufficient, provide reliable data support for subsequent design verification, the design results meet the actual operation requirements, and leave a certain design margin, improving the safety and economy of the power transmission system.

[0038] The additional aspects and advantages of the present invention will become obvious in the following description part, or be understood through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The above - mentioned and / or additional aspects and advantages of the present invention will become obvious and easy to understand from the description of the embodiments in conjunction with the following drawings, where:

[0040] Figure 1 is a flowchart of the design method for the thickness of the bottom plate of the twelve - earth - screw tower foot structure based on the tensile - shear coupling effect according to an embodiment of the present invention;

[0041] Figure 2 is a schematic structural diagram of the twelve - earth - screw tower foot structure according to an embodiment of the present invention.

[0042] Among them, Figures 1 to 2 the corresponding relationship between the reference numerals and the component names in the drawings is:

[0043] 1, bottom plate; 2, main shoe plate; 3, secondary shoe plate; 4, main material; 5, internal earth screw; 6, external earth screw. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0044] In order to more clearly understand the above-mentioned objects, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, without conflict, the embodiments of the present application and the features in the embodiments can be combined with each other.

[0045] In the following description, many specific details are set forth in order to fully understand the present invention. However, the present invention can also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited by the specific embodiments disclosed below.

[0046] The following refers to Figures 1 to 2 to describe a method for designing the thickness of the bottom plate of a twelve-earth screw tower foot structure based on the tensile-shear coupling effect according to some embodiments of the present invention.

[0047] Some embodiments of the present application provide a method for designing the thickness of the bottom plate of a twelve-earth screw tower foot structure based on the tensile-shear coupling effect.

[0048] As Figures 1 to 2 shown, the first embodiment of the present invention proposes a method for designing the thickness of the bottom plate of a twelve-earth screw tower foot structure based on the tensile-shear coupling effect. The twelve-earth screw tower foot structure includes: a main material 4, earth screws, a bottom plate 1, a main shoe plate 2, and a secondary shoe plate 3; the bottom plate 1 is fixedly installed on the ground through earth screws, the main shoe plate 2 is in a cross shape, the cross shape is symmetrically arranged on the bottom plate 1, the secondary shoe plate 3 is vertically arranged at the end of the main shoe plate 2, and the main material 4 is fixedly connected to the main shoe plate 2 through bolts; the cross shape of the main shoe plate 2 divides the bottom plate 1 into four assembly areas, the earth screws are divided into four groups, each group of earth screws includes two outer earth screws 6 and one inner earth screw 5, and the inner earth screw 5 is arranged on the side of the outer earth screw 6 close to the center of the bottom plate 1; one group of earth screws is arranged in each area, and the four groups of earth screws are centrally symmetrically arranged with the center of the main shoe plate 2 as the center and axially symmetrically arranged with the main shoe plate 2 as the axis; as Figure 2 shown is a twelve-earth screw tower foot structure in some implementations. The design of the bottom plate is mainly the design of its thickness, and the thickness of the bottom plate is mainly controlled by the coupling effect of the uplift load and the horizontal shear load. Therefore, when designing its thickness, the combined action of the uplift and shear loads needs to be considered.

[0049] The method includes the following steps:

[0050] S1. According to the distribution of the uplift load borne by the outer and inner earth screws in the assembly area, use the uneven distribution ratio coefficient of the outer and inner earth screws to calculate the internal force of the outer earth screws.

[0051] S2. Establish the relationship between the bottom plate thickness and the internal force of the outer earth screws under the action of only the uplift load.

[0052] S3. Perform stress conversion on the relationship between the bottom plate thickness and the internal force of the external ground screws established in S2 to obtain the expression of the uplift stress borne by the bottom plate.

[0053] S4. Consider the shear effect of the main material on the bottom plate during uplift and calculate the shear stress generated by the shear effect.

[0054] S5. Solve for the minimum thickness of the bottom plate of the twelve-ground-screw tower foot structure according to the fact that the design strength of the bottom plate should satisfy the tensile-shear coupling effect generated after coupling the uplift stress in S3 and the shear stress in S4.

[0055] The second embodiment of the present invention proposes a method for designing the thickness of the bottom plate of a twelve-ground-screw tower foot structure based on the tensile-shear coupling effect. On the basis of the first embodiment, as Figures 1 to 2 shown, it includes the following steps:

[0056] S1. According to the distribution of the uplift load borne by the external and internal ground screws in the assembly area, use the uneven distribution ratio coefficient of the external and internal ground screws to calculate the internal force of the external ground screws.

[0057] In S1, within the assembly area, the distribution of the uplift load borne by the external and internal ground screws is:

[0058]

[0059] Among them, is the internal force of the external ground screw under the action of the uplift load, is the internal force of the internal ground screw under the action of the uplift load, and T is the load effect of the bottom plate.

[0060] The calculation method of the internal force of the external ground screw is:

[0061]

[0062] Among them, is the uneven distribution ratio coefficient of the external and internal ground screws.

[0063] In the above technical solution, the uneven distribution ratio coefficient of the external and internal ground screws is approximated as:

[0064]

[0065] Among them, is the vertical distance from the center of the internal ground screw to the center of the shoe plate; is the vertical distance from the center of the external ground screw to the center of the shoe plate.

[0066] S2. Establish the relationship between the bottom plate thickness and the internal force of the external ground screws only under the action of the uplift load.

[0067] In S2, the relationship between the bottom plate thickness and the internal force of the external ground screws only under the action of the uplift load is:

[0068]

[0069] wherein, is the thickness of the bottom plate; is the vertical distance between the centers of two outer screws within the same assembly area; is the vertical distance from the center of the outer screw to the edge of the bottom plate; is the length of the secondary shoe plate within the assembly area; is the yield strength of the bottom plate.

[0070] S3. Perform stress conversion on the relationship between the bottom plate thickness and the internal force of the outer screw established in S2 to obtain the expression of the uplift stress borne by the bottom plate;

[0071] In S3, in order to achieve the coupling of uplift stress and shear stress, perform stress conversion on the relationship between the bottom plate thickness and the internal force of the outer screw established in S2 to obtain the following expression of the uplift stress borne by the bottom plate:

[0072] .

[0073] S4. Consider the shear effect of the main material on the bottom plate during uplift and calculate the shear stress generated by the shear effect;

[0074] In S4, considering the shear effect of the main material on the bottom plate during uplift, the calculation method of the shear stress is as follows:

[0075]

[0076] wherein, is the thickness of the main shoe plate; is the shear design strength of the bottom plate steel; B is the width of the bottom plate; is the horizontal shear load borne by the bottom plate in the X direction during uplift; is the horizontal shear load borne by the bottom plate in the Y direction during uplift; Figure 2 The directions of and are marked.

[0077] S5. Solve for the minimum thickness of the bottom plate of the twelve-outer-screw tower foot structure according to the fact that the design strength of the bottom plate should satisfy the tensile-shear coupling effect generated by the coupling of the uplift stress in S3 and the shear stress in S4.

[0078] In S5, in order to ensure the design strength of the bottom plate under the tensile-shear coupling action, the uplift stress and shear stress of the bottom plate should meet the following requirements:

[0079]

[0080] wherein, is the partial factor of safety for steel. For Q235, it is taken as 1.09; for Q355, it is taken as 1.15; and for Q420, it is taken as 1.18.

[0081] Substitute the expression of the uplift stress borne by the base plate into the above formula. The calculation method for the minimum thickness of the base plate of the twelve - ground - screw tower - foot structure is as follows:

[0082] 。

[0083] When calculating the minimum thickness of the base plate of the twelve - ground - screw tower - foot structure, the yield - line theory floating coefficient needs to be superimposed. The value of the yield - line theory floating coefficient is not less than 1.1.

[0084] Since there is generally an error of about 10% in the yield - line theory, the yield - line theory floating coefficient can be taken as 1.1. Then the calculation method for the minimum thickness of the base plate of the twelve - ground - screw tower - foot structure is as follows:

[0085]

[0086] When the thickness of the base plate of the twelve - ground - screw tower - foot structure meets the requirements of the above formula, the design strength of the base plate can be ensured, meeting the requirements of engineering design.

[0087] In this specification, the schematic description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0088] Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for designing the thickness of the bottom plate of a twelve - earth - screw tower - foot structure based on the tension - shear coupling effect, the twelve - earth - screw tower - foot structure comprises: main material (4), earth screws, bottom plate (1), main shoe plate (2) and secondary shoe plate (3); the bottom plate (1) is fixedly installed on the ground through earth screws, the main shoe plate (2) is in a cross - shaped structure, the cross - shaped structure is symmetrically arranged on the bottom plate (1), the secondary shoe plate (3) is vertically arranged at the end of the main shoe plate (2), and the main material (4) is fixedly connected with the main shoe plate (2) through bolts; the cross - shaped structure of the main shoe plate (2) divides the bottom plate (1) into four assembly areas, the earth screws are divided into four groups, each group of earth screws includes two outer earth screws (6) and one inner earth screw (5), and the inner earth screw (5) is arranged on the side of the outer earth screw (6) closer to the center of the bottom plate (1); one group of earth screws is arranged in each area, and the four groups of earth screws are centrosymmetrically arranged with the center of the main shoe plate (2) as the center and axially symmetrically arranged with the main shoe plate (2) as the axis; it is characterized by the following steps: S1. According to the distribution of the uplift loads borne by the outer and inner earth screws in the assembly area, and using the non - uniform distribution ratio coefficient of the outer and inner earth screws, calculate the internal force of the outer earth screws; S2. Establish the relationship between the thickness of the bottom plate and the internal force of the outer earth screws under the action of only the uplift load; S3. Conduct stress conversion on the relationship between the thickness of the bottom plate and the internal force of the outer earth screws established in S2 to obtain the expression of the uplift stress borne by the bottom plate; S4. Consider the shear effect of the main material on the bottom plate during uplift and calculate the shear stress generated by the shear effect; S5. According to the design strength of the bottom plate, which should satisfy the tension - shear coupling effect generated by the coupling of the uplift stress in S3 and the shear stress in S4, solve for the minimum thickness of the bottom plate of the twelve - earth - screw tower - foot structure; In S1, in the assembly area, the distribution of the uplift loads borne by the outer and inner earth screws is as follows: Among them, is the internal force of the external screw under the uplift load, is the internal force of the internal screw under the uplift load, and T is the load effect of the bottom plate; The calculation method of the internal force of the outer earth screws is: Among them, is the uneven distribution ratio coefficient of the inner and outer ground screws; The calculation method of the non - uniform distribution ratio coefficient of the outer and inner earth screws is as follows: Among them, is the vertical distance from the center of the inner land screw to the center of the boot plate; is the vertical distance from the center of the outer land screw to the center of the boot plate.

2. According to the method for designing the thickness of the bottom plate of the twelve - earth - screw tower - foot structure based on the tension - shear coupling effect described in claim 1, it is characterized in that, in S2, under the action of only the uplift load, the relationship between the thickness of the bottom plate and the internal force of the outer earth screws is: Among them, is the thickness of the bottom plate; is the vertical distance between the centers of two outer screws within the same assembly area; is the vertical distance from the center of the outer screw to the edge of the bottom plate; is the length of the secondary shoe plate within the assembly area; is the yield strength of the bottom plate.

3. According to the method for designing the thickness of the bottom plate of the twelve - earth - screw tower - foot structure based on the tension - shear coupling effect described in claim 2, it is characterized in that, in S3, conduct stress conversion on the relationship between the thickness of the bottom plate and the internal force of the outer earth screws established in S2 to obtain the following expression of the uplift stress borne by the bottom plate: 。 4. According to the method for designing the thickness of the bottom plate of the twelve - earth - screw tower - foot structure based on the tension - shear coupling effect described in claim 3, it is characterized in that, in S4, considering the shear effect of the main material on the bottom plate during uplift, the calculation method of the shear stress is as follows: Among them, is the thickness of the main shoe plate; is the shear design strength of the bottom plate steel; B is the width of the bottom plate; is the horizontal shear load borne by the bottom plate in the X direction during uplift; is the horizontal shear load borne by the bottom plate in the Y direction during uplift.

5. According to the method for designing the thickness of the bottom plate of the twelve - earth - screw tower - foot structure based on the tension - shear coupling effect described in claim 4, it is characterized in that, in S5, in order to ensure the design strength of the bottom plate under the tension - shear coupling action, the uplift stress and shear stress of the bottom plate should meet the following requirements: Among them, is the partial factor of material for steel.

6. According to the method for designing the thickness of the bottom plate of the twelve - earth - screw tower - foot structure based on the tension - shear coupling effect described in claim 5, it is characterized in that, The calculation method for the minimum thickness of the bottom plate of the twelve - earth - screw tower - foot structure is as follows: 。 7. The design method for the thickness of the bottom plate of the twelve - earth - screw tower - foot structure based on the tensile - shear coupling effect according to any one of claims 1 to 6, characterized in that, in S5, when calculating the minimum thickness of the bottom plate of the twelve - earth - screw tower - foot structure, a yield - line theory floating coefficient needs to be superimposed, and the value of the yield - line theory floating coefficient is not less than 1.1.

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