Method for calculating uplift bearing capacity of screw anchor, storage medium and electronic equipment

Abstract

The invention provides a method for calculating the uplift bearing capacity of a screw anchor, a storage medium and electronic equipment in the technical field of computer-aided design of overhead transmission line screw anchors, the calculation method provides a linear simplified formula Qt / D3 = A * H / D + B for calculating the bearing capacity of a single anchor disc, A and B are simplified coefficients determined for fitting of silty-fine sand soil, and an anchor disc anti-pulling bearing exerting efficiency coefficient eta is introduced to efficiently calculate the bearing capacity of the multi-anchor disc and the anchor group foundation. The problems that a spiral anchor uplift bearing capacity calculation formula is complex, numerous in parameters and low in calculation efficiency are solved, the calculation efficiency is remarkably improved while the accuracy that the error with a standard value is smaller than 5% is guaranteed, and a convenient and reliable tool is provided for spiral anchor foundation design in a silty-fine sand stratum.

Description

Technical Field

[0001] This application relates to the field of computer-aided design technology for helical anchors in overhead transmission lines, specifically a calculation method, storage medium, and electronic device for the pull-out bearing capacity of helical anchors in fine sand. Background Technology

[0002] Helical anchors are particularly suitable as supporting foundations for transmission towers and photovoltaic panel structures. Compared with traditional pile foundations and gravity shallow foundations, helical anchors exhibit significant advantages in complex strata such as soft clay in the Yangtze River basin and interbedded silt and sand in the southeast coastal areas. Their basic design and foundation calculations are crucial for ensuring the quality of foundation construction projects. The complexity of the "anchor-soil" interaction leads to diverse failure modes. A journal article, "Calculation and Analysis of Pull-out Bearing Capacity of Helical Anchor Groups in Silt Soil in Nantong Area," points out that the calculation methods for the bearing capacity of helical anchors are not standardized. The old State Grid Corporation of China enterprise standard Q / GDW 584—2011, "Technical Specification for Design of Helical Anchor Foundations for Overhead Transmission Lines," used a component combination method for uplift stability calculation. The 2018 revision introduced a horizontal force combination coefficient, expanding the selection of anchor plate uplift bearing capacity from various empirical cylindrical shear methods to the soil weight method and bearing capacity method. The power industry standard DL / T 5219—2023, "Code for Design of Foundations for Overhead Transmission Lines," differentiates between shallow and deep anchors in calculating anchor plate uplift bearing capacity. Shallow anchors use a multi-parameter conical failure surface formula, while deep anchors are calculated using formulas including soil unit weight, top anchor plate area, top anchor plate uplift bearing capacity calculation parameters, and cohesive soil anchor plate uplift bearing capacity calculation parameters. The State Grid Corporation of China enterprise standard later evolved into the current enterprise standard Q / GDW 10584—2022, "Code for Design of Helical Anchor Foundations for Overhead Transmission Lines," and subsequent group standard T / CEC. The 5090-2023 "Technical Specification for Helical Anchor Foundation Engineering of Overhead Transmission Lines" proposes a unified limit state design method based on pile foundation theory. It derives a standard formula for calculating the pull-out bearing capacity of helical anchors based on failure mechanism theory. However, this method requires consideration of the burial depth of the top surface of the pull-out shear body, which is related to the influence coefficient of the anchor disc shear cylinder soil height. Both factors jointly affect the calculation of the anchor pull-out bearing capacity. Furthermore, the influence coefficient of lateral pressure must be considered, resulting in low efficiency and a high risk of error in pull-out bearing capacity calculations. Currently, there is also a method for predicting the pull-out limit bearing capacity of grouting helical anchors in gravelly soil based on finite element analysis, as disclosed in patent application CN121145569A. This method determines the critical bearing stress through stress analysis and, combined with experimental correction, improves accuracy. Therefore, existing helical anchor pull-out bearing capacity calculations suffer from diverse formula forms and complex calculations, and the critical anchor disc spacing ratio lacks clear and quantitative guidance applicable to fine sand. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this application provides a method, storage medium, and electronic device for calculating the pull-out bearing capacity of spiral anchors in fine sand, thereby solving the problems of complex calculation formulas, numerous parameters, and low calculation efficiency of existing spiral anchor pull-out bearing capacity calculation technologies.

[0004] To achieve the above objectives, this application provides the following technical solution: A method for calculating the pull-out bearing capacity of a spiral anchor, characterized by comprising the following steps: Based on the borehole parameter data, it was determined that the soil layer where the helical anchor foundation is located is silty fine sand, and the geometric parameters of the helical anchor were obtained. The geometric parameters include at least the diameter of the anchor disc. D and anchor plate burial depth H When the helical anchor has multiple anchor discs, the geometric parameters include the anchor disc spacing. S ; Calculate the burial depth ratio H / D The burial depth of the helical anchor is determined by comparing it with a threshold value. When the burial depth is deep, the pull-out bearing capacity of a single anchor disc is... Q t Through formula Q t / D 3 =A× H / D The calculation is performed using +B, where A is the first simplification coefficient and B is the second simplification coefficient. The pull-out bearing capacity of a multi-anchor disc helical anchor is determined by the formula. Q g = or ∑ Q t Calculation, where or To maximize the uplift load capacity of the anchor disc, the uplift load capacity of the anchor disc should be maximized. or By based on anchor plate spacing S With anchor plate diameter D ratio S / D Sure, S / D ≥2.

[0005] Preferably, the density of the fine sand is medium dense, and the first simplification coefficient A = 81.5 kN / m³. 3 The second simplification factor B = -148 kN / m 3 .

[0006] Preferably, the criterion for determining whether the burial depth is deep is the burial depth ratio. H / D ≥4.

[0007] Preferably, the anchor plate has a pull-out bearing capacity utilization efficiency coefficient. or The rules for determining the value are as follows: S / D When ≥4, or Take 1.00, when S / D When =3, or Take 0.80, when S / D At 2 o'clock, or Take 0.55.

[0008] Preferably, the diameter of the anchor plate D The value can be 650, 810, or 960 mm.

[0009] Preferably, the type of soil layer is determined by indoor earthwork tests.

[0010] Preferably, the density state is determined by in-situ test results.

[0011] Preferably, the pull-out bearing capacity of the group anchor spiral anchor foundation is determined by the formula... Q =∑ Q g Calculation, where Q g The pull-out bearing capacity of a single multi-anchor disc spiral anchor.

[0012] Based on the same inventive concept, this application also achieves this through the following technical solutions: A storage medium having a computer program stored thereon, which, when executed by a processor, implements the method for calculating the pull-out bearing capacity of a helical anchor as described in any of the preceding claims.

[0013] An electronic device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the computer program, implements the method for calculating the pull-out bearing capacity of a helical anchor as described in any of the preceding claims.

[0014] Compared with existing technologies, the advantages of this solution are as follows: through systematic numerical simulation and data fitting, it was found that for deep-buried helical anchors with a burial depth ratio of not less than 4 in silty fine sand strata, the normalized bearing capacity ( Q t / D³) A clear linear relationship exists between the anchor plate and the burial depth ratio, thus eliminating complex theoretical derivations. A simple linear formula is creatively proposed to directly describe this core relationship, greatly simplifying the calculation process. Based on the linear formula for a single anchor plate, this application introduces the concept of "anchor plate pull-out bearing capacity utilization efficiency η" and provides specific efficiency coefficients corresponding to different anchor plate spacings. This makes the calculation of the overall bearing capacity of multi-anchor plate and group anchor foundations exceptionally simple. While improving calculation efficiency, this scheme also ensures an accuracy of less than 5% error compared to the standard value. Attached Figure Description

[0015] Figure 1 This is a schematic diagram illustrating the derivation process of one embodiment of the method of this application; Figure 2 The curve showing the relationship between the uplift bearing capacity coefficient Nγ and the burial depth ratio H / D; Figure 3 The curves show the relationship between the pull-out bearing capacity utilization efficiency of the double-anchor spiral anchor and the anchor plate spacing ratio for two different disc diameters. The horizontal axis represents the anchor plate spacing ratio, and the vertical axis represents the calculated pull-out bearing capacity utilization efficiency of the double-anchor spiral anchor. The first number in the curve label represents the anchor diameter. Figure 4 The curves show the relationship between the pull-out bearing capacity utilization efficiency of the multi-anchor spiral anchor with two different disc diameters and the anchor plate spacing ratio. The horizontal axis represents the anchor plate spacing ratio, and the vertical axis represents the calculated pull-out bearing capacity utilization efficiency of the multi-anchor spiral anchor. Figure 5 The curve represents the relationship between the pull-out bearing capacity utilization efficiency of the multi-anchor spiral anchor and the burial depth ratio of each anchor plate. The horizontal axis represents the burial depth ratio of the anchor plates, and the vertical axis represents the calculated pull-out bearing capacity utilization efficiency of the multi-anchor spiral anchor. The first number in the curve label is the diameter of the anchor plate, the number after B is the burial depth ratio of the first anchor, and the number after N is the number of anchor plates. Figure 6 for Q t / D 3 and parameters H / D Relationship curve graph. Detailed Implementation

[0016] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0017] This embodiment focuses on the design and construction of transmission line towers using spiral anchors in silty-fine sand soil in Nantong, Jiangsu Province. This region primarily consists of medium-dense silty sand or fine sand. The single-anchor spiral anchors used in this embodiment have two diameters: 650mm and 810mm. The multi-anchor spiral anchors employ three specifications: a first specification with an anchor depth of 7020 / 9300mm, an anchor diameter of 810mm, and an anchor spacing of 2280mm; a second specification with an anchor depth of 7020 / 9300mm, an anchor diameter of 960mm, and an anchor spacing of 2280mm; and a third specification with an anchor depth of 6020 / 8300mm, an anchor diameter of 810mm, and an anchor spacing of 2280mm. The group-anchor spiral anchors are configured using four multi-anchor spiral anchors of the first specification.

[0018] First, based on the borehole parameter data, the soil type is determined through indoor soil tests, and the soil parameters are determined through in-situ test results. The soil parameters within a depth of 2 times the length of the spiral anchor are determined by a weighted average method with soil layer thickness as the weight, including compaction state, unit weight, density, internal friction angle, cohesion, compression modulus, and lateral friction.

[0019] Then, the pull-out bearing capacity specifications for single-anchor-plate spiral anchors, multi-anchor-plate spiral anchors, and group-anchor spiral anchors are calculated using the formulas in Q / GDW 10584—2022 "Design Specification for Spiral Anchor Foundations of Overhead Transmission Lines".

[0020] Then, based on literature and numerical simulation results, the pull-out bearing mechanism of the helical anchor in silty fine sand was determined. First, the pull-out process of a single anchor disc helical anchor was numerically simulated to determine the critical burial depth ratio. The relationship curve between the pull-out load Q and the displacement u was plotted to determine the ultimate pull-out bearing capacity of the helical anchor under various working conditions, and the pull-out bearing capacity coefficient was adopted. N γ After normalization, the uplift bearing capacity coefficient is plotted. N γ Ratio to burial depth H / D Relationship curves, such as Figure 2 As shown, the peak point is at the critical burial depth ratio of 5. The uplift bearing capacity coefficient is calculated using the formula... N γ = Q u / γ AH ,in Q u γ represents the ultimate pull-out bearing capacity of the helical anchor, and γ is the unit weight of the soil. A The area of ​​the anchor plate (A here has a different meaning from the first simplification coefficient). H The depth of the anchor plate.

[0021] The upward pull-out process of the multi-anchor helical anchor was simulated again to determine the critical spacing ratio. Similarly, the relationship between the upward pull-out load Q and the displacement u was plotted to determine the ultimate pull-out bearing capacity of the entire helical anchor and each anchor plate under each working condition, and the efficiency of the pull-out bearing capacity utilization was calculated. Figure 3 , Figure 4 As shown. When the anchor spacing S ≥ 4D, the pull-out bearing efficiency of each anchor exceeds 90%, and the overall pull-out bearing efficiency of the helical anchor is the lowest at 93.2%; when the anchor spacing... S =3 D At that time, the load-bearing efficiency of the lower anchor plate is 70%–87%, and the overall pull-out load-bearing efficiency of the helical anchor is 80%–90%; when the anchor plate spacing S =2 D At this point, the overall pull-out bearing efficiency of the helical anchor is at its maximum of 67.4%. Therefore, the critical spacing ratio ranges from 3.0 to 4.0. That is, for multi-anchor helical anchors, when the ultimate displacement is reached, the first anchor is almost unaffected by the interaction between the anchor discs, and its pull-out bearing efficiency reaches 95% or higher. However, the lower anchors are significantly affected by the interaction, and the anchor disc spacing... S Greater than 4 D At that time, the lower anchor plate operates at an efficiency of over 90%, the overall anchor operation efficiency exceeds 93%, the two anchor plates bear load independently, and the anchor plate spacing is [missing information]. S Less than 3 D At that time, the soil between the anchor plates is sheared as a whole, and the bearing capacity of the anchor is less than 80% utilized.

[0022] Since most actual spiral anchor projects involve deep-buried anchors, this solution proposes simplified formulas primarily for deep-buried anchors. Q t / D 3 =A×H / D+B, plotting parameters for different disk diameters. Q t / D 3 and H / D Relationship curves, such as Figure 6 As shown, for Q t / D 3 and H / D The relationship curve was fitted, and the first simplification coefficient A and the second simplification coefficient B were obtained as 81.5 kN / m. 3 -148kN / m 3 Although the critical burial depth ratio for fine sand is 5, the transition from shallow to deep burial is a gradual process; therefore, this scheme also considers a burial depth ratio of 4. Furthermore, based on actual engineering projects, the scope of application of the simplified formula, i.e., the burial depth ratio, is finally determined. H / D ≥4.

[0023] The design specifications for spiral anchors impose certain limitations on the diameter of the anchor disc, and the simplified formula proposed in this scheme has good applicability within this range.

[0024] Since the pull-out bearing capacity of a helical anchor is mainly borne by the anchor disc during the pull-out process, and the anchor bolt contributes less than 5% of the bearing capacity, the anchor bolt bearing capacity is not considered in this embodiment. Based on the aforementioned pull-out simulation analysis of a multi-anchor-disc helical anchor, the pull-out bearing capacity of a multi-anchor-disc helical anchor is determined by the formula... Q g = or ∑ Q t Calculation, where or To maximize the uplift load capacity of the anchor disc, the uplift load capacity of the anchor disc should be maximized. or By considering the anchor spacing S and the anchor diameter D ratio S / D Sure, S / D ≥2, in this embodiment, or The results were obtained through finite element numerical simulation of the pull-out resistance of spiral anchors in fine sand. S / D When ≥4, or Take 1.00, when S / D When =3, or Take 0.80, when S / D When =2, or Take 0.55.

[0025] The pull-out bearing capacity of a multi-anchor spiral anchor foundation is expressed by the formula. Q =∑ Q g Calculation, where Q g The pull-out bearing capacity of a single multi-anchor disc spiral anchor.

[0026]

[0027]

[0028]

[0029] Tables 1-3 compare the values ​​specified in the current standard Q / GDW 10584—2022 "Design Code for Helical Anchor Foundations of Overhead Transmission Lines" with the calculated values ​​from the formula in this scheme. The error between the two is less than 5%. Based on the same inventive concept, different soil types, such as medium sand and coarse sand, follow the same simplified formula according to their bearing mechanisms and deep burial conditions. The first simplification coefficient A and the second simplification coefficient B are different and need to be calculated. The inventive concept is the same.

[0030] Based on the same inventive concept, this application also discloses an embodiment of a storage medium on which a computer program is stored. When the computer program is executed by a processor, it implements the calculation method of the pull-out bearing capacity of the spiral anchor as described in any of the preceding claims. The storage medium can be an SSD, HDD, SD Card, or other media.

[0031] Based on the same inventive concept, this application also discloses an embodiment of an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the calculation method for the pull-out bearing capacity of the helical anchor as described in any of the preceding claims. The electronic device may be a computer or the like.

[0032] The above description is only a preferred embodiment of the present solution, but the scope of protection claimed by the present solution is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in this application, based on the technical solution and inventive concept of this application, should be included within the scope of protection of this application.

Claims

1. A method of calculating the pullout capacity of a screw anchor, characterized in that comprising the steps of: According to the drilling parameter data, it is determined that the soil layer where the screw anchor foundation is located is silty fine sand, and geometric parameters of the screw anchor are obtained, the geometric parameters at least including an anchor disc diameter D and an anchor disc embedment depth H When the screw anchor is a multi-anchor disc, the geometric parameters include an anchor disc spacing S ; Computing the burial depth ratio H / D And the threshold value is compared to determine the burial state of the spiral anchor, when the burial state is deep burial, the single anchor plate has a large anti-pulling bearing capacity Q t Through the formula Q t / D 3 =A× H / D +B is calculated, wherein A is a first simplified coefficient, and B is a second simplified coefficient The uplift capacity of multi-plate helical anchors is calculated by the formula Q g = η ∑ Q t wherein η The uplift capacity of the anchor plate is determined by the ratio of the distance between the anchor plates η to the anchor plate diameter S , D / S / D , S / D ≥ 2.

2. The method of calculating the uplift capacity of a screw anchor according to claim 1, wherein: The powder fine sand compactness state is medium density, the first simplified coefficient A=81.5kN / m 3 , the second simplified coefficient B=-148kN / m 3 .

3. The method of calculating the uplift capacity of a screw anchor according to claim 2, wherein: The buried state is deep buried, and the judgment standard of the buried state is a buried ratio H / D ≥ 4.

4. The method of claim 2, wherein: The anchor disc anti-pulling bearing efficiency coefficient η The value rule is: S / D When ≥4, η Take 1.00, when S / D =3, η Take 0.80, when S / D =2, η Take 0.

55.

5. The method of calculating the uplift capacity of a screw anchor according to claim 1, wherein: The anchor diameter D 650 or 810 or 960 mm.

6. The method of calculating the uplift capacity of a screw anchor according to claim 1, wherein: The type of soil is determined by laboratory soil test.

7. The method of calculating the uplift capacity of a screw anchor according to claim 2, wherein: The state of compaction is determined by in-situ test results.

8. The method of calculating the uplift capacity of a screw anchor according to claim 1, wherein: The uplift capacity of group anchor helical anchor foundations is calculated by the formula Q =∑ Q g The uplift capacity of a single multi-plate helical anchor is calculated by the formula Q g where 9. A storage medium having stored thereon a computer program, characterized in that: The computer program, when executed by the processor, implements the method of calculating the uplift capacity of a screw anchor according to any one of claims 1 to 8.

10. An electronic device comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that: The processor, when executing the computer program, implements the method of calculating the uplift capacity of a screw anchor in silty sand according to any one of claims 1 to 8.

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