CN116805123A - Design method, checking method and lattice tower independent foundation - Google Patents
Design method, checking method and lattice tower independent foundation Download PDFInfo
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- 238000004364 calculation method Methods 0.000 claims abstract description 41
- 239000004567 concrete Substances 0.000 claims description 94
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- 210000002435 tendon Anatomy 0.000 claims description 16
- 229910001294 Reinforcing steel Inorganic materials 0.000 claims description 14
- 230000006872 improvement Effects 0.000 claims description 14
- 238000010008 shearing Methods 0.000 claims description 10
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- 238000010438 heat treatment Methods 0.000 claims description 4
- 230000002301 combined effect Effects 0.000 claims description 3
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Classifications
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D27/00—Foundations as substructures
- E02D27/32—Foundations for special purposes
- E02D27/42—Foundations for poles, masts or chimneys
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D27/00—Foundations as substructures
- E02D27/32—Foundations for special purposes
- E02D27/44—Foundations for machines, engines or ordnance
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F30/00—Computer-aided design [CAD]
- G06F30/20—Design optimisation, verification or simulation
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F2111/00—Details relating to CAD techniques
- G06F2111/04—Constraint-based CAD
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F2119/00—Details relating to the type or aim of the analysis or the optimisation
- G06F2119/04—Ageing analysis or optimisation against ageing
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F2119/00—Details relating to the type or aim of the analysis or the optimisation
- G06F2119/14—Force analysis or force optimisation, e.g. static or dynamic forces
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/70—Wind energy
- Y02E10/72—Wind turbines with rotation axis in wind direction
Abstract
The application relates to the technical field of fan foundations, in particular to a design method and an inspection method of an independent foundation of a lattice tower and the lattice tower. Aiming at an independent foundation under each lattice tower corner post, the scheme carries out body type design, stress checking calculation and fatigue checking calculation; the corner posts are connected with the independent foundations by adopting anchor bolts and prestressed reinforcement, and local bearing checking calculation is carried out on the related content of the prestressed anchor bolts and the prestressed reinforcement tensioning anchor plates according to the connection mode; the foundations are connected through foundation beams, and stress and deformation checking calculation is conducted on the foundation beams. The design calculation method suitable for the independent foundation of the lattice tower is provided by utilizing the current standard and the foundation stress principle, the design theory of the independent foundation is perfected, and the design basis is provided for the subsequent popularization of the lattice tower and the independent foundation thereof.
Description
Technical Field
The application relates to the technical field of fan foundations, in particular to a design method and an inspection method of an independent foundation of a lattice tower and the lattice tower.
Background
In recent years, with large-scale development of wind power generation, china has become the first country of global wind power installation capacity. In the trend of the super-long blades, super-high tower barrels and large capacity development of units in the future, the prestressed steel pipe concrete lattice tower has obvious advantages in the aspects of stress efficiency, material consumption, industrialized construction degree, supply chain system and the like. The original fan foundation is large in size and high in construction technical requirements, and particularly, temperature stress cracks of concrete caused by temperature difference due to cement hydration heat are prevented in construction, and the cost is high. For this reason, to lattice formula tower frame design for four post under independent basis, connect through the foundation roof beam between each basis, adopt prestressing force crab-bolt + prestressing tendons to connect between basis and the corner post, this basis cost is less than concrete tower section of thick bamboo basis, and area is little, with low costs.
Therefore, in order to popularize the prestressed steel pipe concrete lattice tower and realize the cost reduction of the tower barrel structure in the 'low price age', more theoretical calculations are needed to be carried out on the independent foundation of the lattice tower so as to guide the design of the independent foundation of the lattice tower in engineering.
Disclosure of Invention
Aiming at the defects existing in the prior art, the application provides a design method and a checking method of an independent foundation of a lattice tower and the lattice tower, so that the design of the independent foundation of the lattice tower can be guided in engineering, the design reliability of the tower can be effectively improved, and the safety risk is reduced.
In a first aspect, the present application provides a method of designing an independent foundation for a lattice tower.
In a first implementation, a method for designing an independent foundation of a lattice tower includes:
constructing a plurality of foundation pile constraint formulas according to foundation pile stress parameters based on the combined effect of the load efficiency standards of the fan tower;
and respectively designing the foundation piles and the bearing platforms according to a plurality of foundation pile constraint formulas.
In combination with the first implementation manner, in a second implementation manner, constructing a plurality of foundation pile constraint formulas according to the foundation pile stress parameters includes:
respectively constructing a first foundation pile constraint formula and a second foundation pile constraint formula according to the single-pile vertical force and the single-pile vertical bearing force characteristic value;
and constructing a third foundation pile constraint formula according to the standard value of the pulling-out resistance limit bearing capacity of the foundation pile and the self-reconstruction of the foundation pile when the single pile pulling-out force and the group pile are not integrally damaged.
In combination with the second implementation manner, in a third implementation manner, designing the foundation pile and the bearing platform according to a plurality of foundation pile constraint formulas includes:
obtaining the number of foundation piles and the size of the foundation piles according to a plurality of foundation pile constraint formulas, wherein the size of the foundation piles comprises Zhou Shenchang and an end surface of the foundation piles;
and obtaining the size of the bearing platform according to the size of the foundation pile.
With reference to the third implementation manner, in a fourth implementation manner, obtaining the size of the bearing platform according to the size of the foundation pile includes:
designing the size of the bearing platform based on the first bearing platform constraint condition and the second bearing platform constraint condition; the constraint condition of the first bearing platform is that the distance value between the edge of the bearing platform and the center of the foundation pile is larger than or equal to the diameter or the side length of the foundation pile; and the constraint condition of the second bearing platform is that the edge picking length of the bearing platform is larger than or equal to a first threshold value.
In a second aspect, the present application provides a lattice tower.
In a fifth possible implementation, a lattice tower includes:
an independent foundation designed according to the design method of the independent foundation of the lattice tower; the independent foundation comprises a foundation pile and a bearing platform;
the foundation connecting beam is arranged at a preset position below the top surface of the bearing platform, and adjacent bearing platforms are connected through the foundation connecting beam.
In a third aspect, the application provides a method of checking an independent foundation of a lattice tower.
In a sixth implementation manner, a checking method for independent foundations of a lattice tower, based on the lattice tower, includes:
carrying out stress checking calculation on the part of the prestressed tendon stretching anchor plate, the prestressed anchor bolt and the section of the foundation beam; the stress checking calculation of the prestressed anchor bolt comprises the checking calculation of the strength of the prestressed anchor bolt, the checking calculation of the shearing resistance of the prestressed anchor bolt, the checking calculation of the local compressive stress, the checking calculation of the cross section size of the local compression area and the checking calculation of the bearing capacity of the local compression area.
In combination with the sixth implementation manner, in a seventh implementation manner, the performing a stress checking calculation on the part of the prestressed tendon stretching anchor plate includes:
and checking whether the local stress of the prestressed tendon tensioning anchor plate meets the requirement or not according to the structural importance coefficient, the height influence coefficient of the punched bearing capacity section of the bearing platform, the strength improvement coefficient of the concrete when the concrete is locally compressed, the concrete axle center compressive strength design value and the concrete local compression clear area. Therefore, the partial pressure bearing checking calculation is carried out on the prestressed tendon stretching anchor plate, so that the partial pressure damage of the end part of the anchor plate can be prevented.
With reference to the sixth implementation manner, in an eighth implementation manner, the checking calculation of the strength of the prestressed anchor bolt includes:
obtaining the strength of the prestressed anchor bolt according to the maximum pulling force standard value acting on the horizontal bar anchor bolt under the combination of the working condition coefficient and the load effect standard;
judging whether the strength of the prestressed anchor bolt meets the requirement according to the lowest tensile strength of the anchor bolt after heat treatment and the effective area of the screw thread of the anchor bolt.
With reference to the sixth implementation manner, in a ninth implementation manner, the checking calculation of the bearing capacity of the local compression area includes:
determining the cross-sectional area of the concrete core within the surface range of the indirect reinforcing steel bar according to the calculated bottom area of the local compression;
determining and configuring the local compressive bearing capacity improvement coefficient of the indirect steel bar according to the concrete core cross-sectional area and the concrete local compressive area within the surface range of the indirect steel bar;
and judging whether the bearing capacity of the local compression area meets the requirement according to the local compression bearing capacity improvement coefficient of the indirect reinforcing steel bars, the reduction coefficient of the indirect reinforcing steel bars to the concrete constraint and the reinforcing steel bar mesh volume reinforcing steel bar arrangement rate.
With reference to the sixth implementation manner, in a tenth implementation manner, the method further includes:
calculating a first fatigue life of the steel pipe according to the first positive stress of the steel pipe and the second positive stress of the steel pipe;
calculating a second fatigue life of the steel pipe according to the shear stress of the steel pipe;
and checking whether the fatigue strength of the steel pipe meets the requirement or not by using a linear damage accumulation criterion according to the first fatigue life and the second fatigue life of the steel pipe.
According to the technical scheme, the beneficial technical effects of the application are as follows:
1. constructing a plurality of foundation pile constraint formulas according to foundation pile stress parameters based on the combined effect of the load efficiency standards of the fan tower; and design foundation pile and cushion cap respectively according to a plurality of foundation pile constraint formulas, this scheme has proposed the design method of lattice formula independent basis, can instruct the design of lattice formula pylon in the engineering, can effectively improve the design reliability of pylon, reduces the security risk.
2. The stress checking calculation is carried out on the part of the prestressed tendon stretching anchor plate, the prestressed anchor bolt and the section of the foundation beam, so that the design of the lattice type tower can be pointed out in engineering, the design reliability of the tower can be effectively improved, and the safety risk is reduced.
3. Aiming at an independent foundation under each lattice tower corner post, the scheme carries out body type design, stress checking calculation and fatigue checking calculation; the corner posts are connected with the independent foundations by adopting anchor bolts and prestressed reinforcement, and local bearing checking calculation is carried out on the related content of the prestressed anchor bolts and the prestressed reinforcement tensioning anchor plates according to the connection mode; the foundations are connected through foundation beams, and stress and deformation checking calculation is conducted on the foundation beams. The design calculation method suitable for the independent foundation of the lattice tower is provided by utilizing the current standard and the foundation stress principle, the design theory of the independent foundation is perfected, and the design basis is provided for the subsequent popularization of the lattice tower and the independent foundation thereof.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below. Like elements or portions are generally identified by like reference numerals throughout the several figures. In the drawings, elements or portions thereof are not necessarily drawn to scale.
FIG. 1 is a schematic diagram of a design method of a lattice tower independent foundation provided in this embodiment;
FIG. 2 is a schematic structural diagram of an independent foundation according to the present embodiment;
FIG. 3 is a plan view of an independent foundation provided in this embodiment;
reference numerals:
1-lattice tower corner posts; 2-pre-stressing anchor bolts; 3-flanges; 4-upper anchor plate; 5-high-strength grouting material; 6-prestress rib; 7-a bearing platform; 8-pile foundation; 9-foundation beams; 10-lower anchor plate; and 11-tensioning the anchor plate by the prestressed tendons.
Detailed Description
Embodiments of the technical scheme of the present application will be described in detail below with reference to the accompanying drawings. The following examples are only for more clearly illustrating the technical aspects of the present application, and thus are merely examples, and are not intended to limit the scope of the present application.
It is noted that unless otherwise indicated, technical or scientific terms used herein should be given the ordinary meaning as understood by one of ordinary skill in the art to which this application belongs. The terms first, second and the like in the description and in the claims of the embodiments of the disclosure and in the above-described figures are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate in order to implement the embodiments of the disclosure described herein. Furthermore, the terms "comprise" and "have," as well as any variations thereof, are intended to cover a non-exclusive inclusion. The term "plurality" means two or more, unless otherwise indicated. In the embodiment of the present disclosure, the character "/" indicates that the front and rear objects are an or relationship. For example, A/B represents: a or B. The term "and/or" is an associative relationship that describes an object, meaning that there may be three relationships. For example, a and/or B, represent: a or B, or, A and B. The term "corresponding" may refer to an association or binding relationship, and the correspondence between a and B refers to an association or binding relationship between a and B.
In some embodiments, as shown in connection with fig. 2 and 3, in the lattice tower, each lattice tower corner post 1 comprises an independent foundation below each lattice tower corner post 1, each independent foundation comprising a bearing platform 7 and a pile foundation 8, the lattice tower corner posts 1 are fixed to the upper anchor plates 4 by means of pre-stressed anchor bolts 2 and flanges 3, and the upper anchor plates 4 are fixed to the bearing platform 7 by means of high-strength grouting material 5. The bottom of the lattice tower corner column 1 is provided with a prestressed rib 6, and the prestressed rib 6 penetrates through a lower anchor plate 10 and is fixed with a bearing platform 7 through a prestressed rib tensioning anchor plate 11. Pile foundation 8 is arranged at the bottom of bearing platform 7, and adjacent bearing platforms 7 are connected through foundation beams 9.
Alternatively, the corner posts and the independent foundation are connected by anchor bolts and prestressed tendons.
Optionally, the independent foundation is a gravity foundation or a pile foundation.
Alternatively, the foundation is connected to the corner post by a prestressed anchor, a prestressed tendon, a prestressed anchor+prestressed tendon, or other connection methods.
Optionally, the base body type design and the stress checking calculation meet current standards of the country, region or industry.
With reference to fig. 1, this embodiment provides a design method for an independent foundation of a lattice tower, including:
s1, under the combined action of load efficiency standards of a fan tower, constructing a plurality of foundation pile constraint formulas according to foundation pile stress parameters;
a1, constructing a first foundation pile constraint formula according to the vertical force of the single pile and the characteristic value of the vertical bearing force of the single pile; the first foundation pile constraint formula is that the vertical force of the foundation pile is smaller than or equal to the characteristic value of the vertical bearing force of the single pile;
a11, determining vertical force of foundation pile
Wherein N is ik For foundation pile vertical force, N k The vertical force acting on the top surface of a bearing platform of the pile foundation under the combination of load effect standards is in units of kN; g k G is the sum of the dead weights of the bearing platform and the soil on the bearing platform k Deducting the buoyancy of water from the part below the groundwater level; n is the number of piles; g p Is the dead weight of foundation piles, the unit is kN, G is below the ground water level p Taking the floating weight;
a12, determining standard value of vertical ultimate bearing capacity of single pile
Q uk ＝uΣq sik l i +q pk A p ；
Wherein Q is uk Is the standard value of the vertical ultimate bearing capacity of a single pile, q sik The standard value of the limiting side resistance of the ith layer of soil at the pile side is the unit kPa; u is the circumference of the foundation pile body, and the unit is m; l (L) i The unit m is the thickness of foundation piles penetrating through the ith layer of soil; q pk Is at the limit ofEnd resistance standard value, unit kPa; a is that p Is the pile end area, unit um 2 。
A13, determining the characteristic value of the vertical bearing capacity of the single pile
R a ＝Q uk /K；
Wherein R is a Is the characteristic value of the vertical bearing capacity of a single pile, Q uk The standard value of the vertical ultimate bearing capacity of the single pile is K, and the safety coefficient is K. In some embodiments, K has a value of 2.0.
A14, constructing a first foundation pile constraint formula according to the vertical force and the vertical bearing force characteristic value of the single pile, wherein the first foundation pile constraint formula is as follows;
N ik ≤R a ；
wherein N is ik Under the action of a load effect standard combined axle center or eccentric vertical force, the vertical force of the ith foundation pile or the ith composite foundation pile is in kN; r is R a Is a vertical bearing capacity characteristic value of a single pile.
A2, constructing a second foundation pile constraint formula; the second foundation pile constraint formula is that the limit value of the vertical force of the single pile is smaller than or equal to the preset multiple of the characteristic value of the vertical bearing force of the single pile.
A21, determining vertical force limit value of foundation pile
The calculation formula is that
Wherein N is ikmax For foundation pile vertical force limit value, M zk 、M yk The moment of the y and z main shafts passing through the centroid of the pile group is respectively the unit kN.m, which acts on the bottom surface of the bearing platform under the action of the load effect standard combination eccentric vertical force; z i 、y i And the distance between the ith foundation pile and the j foundation pile or between the ith foundation pile and the z axis is in m.
In some embodiments, z i 、y i Firstly, setting the initial value, and taking the initial value into the constraint formula, and calculating until the requirement is met.
A22, constructing a second foundation pile constraint formula, which is as follows: n (N) ikmax ≤1.2R a 。
A3, constructing a third foundation pile constraint formula according to the single pile pulling force, the standard value of the pulling-resistant limit bearing capacity of the foundation pile when the pile group is in non-integral damage and the foundation pile self-reconstruction; the third foundation pile constraint formula is that the single pile pulling force is smaller than a preset value, and the preset value is the sum of half of the standard value of the pulling-resistant ultimate bearing force and the self weight of the foundation pile.
A31, determining the foundation pile pulling force under the load effect standard combination;
wherein N is ikb For the foundation pile pulling force under the load effect standard combination, N k The vertical force acting on the top surface of a bearing platform of the pile foundation under the combination of load effect standards is in units of kN; g k G is the sum of the dead weights of the bearing platform and the soil on the bearing platform k Deducting the buoyancy of water from the part below the groundwater level; n is the number of piles, M zk 、M yk The moment of the y and z main shafts passing through the centroid of the pile group is respectively the unit kN.m, which acts on the bottom surface of the bearing platform under the action of the load effect standard combination eccentric vertical force; z i 、y i And the distance between the ith foundation pile and the j foundation pile or between the ith foundation pile and the z axis is in m.
A32, determining the standard value of the pulling-resistant ultimate bearing capacity of the foundation piles when the pile groups are in non-integral damage
T uk ＝Σλ i q sik ul i ；
Wherein T is uk Standard value of resistance to plucking limit bearing capacity of foundation pile when pile group is not integrally destroyed, q sik The standard value of the limiting side resistance of the ith layer of soil at the pile side is the unit kPa; u is the circumference of the foundation pile body, and the unit is m; l (L) i The unit m is the thickness of foundation piles penetrating through the ith layer of soil; lambda, lambda i Is a pull-out resistance coefficient.
In some embodiments, λ when the earth is sand i The value range is 0.5-0.7, and lambda is found when the soil is cohesive soil or powdered soil i The value range is 0.7-0.8, and lambda is measured when the ratio of pile length to pile diameter is less than 20 i Taking the minimum value.
A33, constructing a third foundation pile constraint formula:
N ikb ≤T uk 2+G p ；
wherein N is ikb The foundation pile pulling force under the load effect standard combination is given by the unit kN; t (T) uk The standard value of the pulling-resistant ultimate bearing capacity of foundation piles is given by the units kN and G when the pile groups are not integrally damaged p Is the dead weight of foundation piles, the unit is kN, G is below the ground water level p Taking the floating weight.
Alternatively, the arrangement of the foundation piles is required to meet the minimum center-to-center distance of 4.0d ', d' being the diameter of the foundation piles.
S2, respectively designing foundation piles and bearing platforms according to a plurality of foundation pile constraint formulas.
Optionally, designing the cap size based on the first cap constraint and the second cap constraint; the constraint condition of the first bearing platform is that the distance value between the edge of the bearing platform and the center of the foundation pile is larger than or equal to the diameter or the side length of the foundation pile; and the constraint condition of the second bearing platform is that the edge picking length of the bearing platform is larger than or equal to a first threshold value.
Optionally, the first threshold is 150mm.
In some embodiments, a lattice tower includes: an independent foundation designed according to the design method of the independent foundation of the lattice tower; the independent foundation comprises a foundation pile and a bearing platform; the foundation connecting beam is arranged at a preset position below the top surface of the bearing platform, and adjacent bearing platforms are connected through the foundation connecting beam.
In some embodiments, the foundation tie beam is disposed about 300mm below the top surface of the platform.
In some embodiments, a method of checking an independent foundation of a lattice tower, based on the lattice tower, includes:
b1, carrying out stress checking calculation on the part of the prestressed tendon stretching anchor plate, wherein the method comprises the following steps: and checking whether the local stress of the prestressed tendon tensioning anchor plate meets the requirement or not according to the structural importance coefficient, the height influence coefficient of the punched bearing capacity section of the bearing platform, the strength improvement coefficient of the concrete when the concrete is locally compressed, the concrete axle center compressive strength design value and the concrete local compression clear area.
In some embodiments, the prestressing forceThe partial stress of the tendon stretching anchor plate meets the formula gamma 0 F l ≤1.35β c β l f c A ln The method comprises the steps of carrying out a first treatment on the surface of the Wherein, gamma 0 As a structural importance coefficient beta c For the influence coefficient of the height of the section of the bearing platform subjected to punching bearing capacity, when h is less than or equal to 800mm, beta is c Taking 1.0, when h is more than or equal to 2000mm, beta c Taking 0.9, and taking a value according to a linear interpolation method when the h is more than 800mm and less than 2000 mm; beta l To increase the strength of the concrete when locally pressed, and is 1 to be less than or equal to beta l ≤3，A b Calculate the floor area for local compression, A l The local pressure area of the concrete is; f (f) c The design value of the compressive strength of the concrete axle center is designed; a is that ln For the concrete local compression clear area, for the post-tensioning member A ln And subtracting the areas of the pore passages and the groove parts from the local compression area of the concrete.
In some embodiments, the structural importance coefficient γ 0 ＝1.1。
B2, carrying out stress checking calculation on the prestressed anchor bolt, including: checking the strength of the prestressed anchor bolts, checking the shearing resistance of the prestressed anchor bolts, checking the local compressive stress, checking the cross section size of the local compression area, and checking the bearing capacity of the local compression area.
B21, checking and calculating the strength of the prestressed anchor bolt, including: obtaining the strength of the prestressed anchor bolt according to the maximum pulling force standard value acting on the horizontal bar anchor bolt under the combination of the working condition coefficient and the load effect standard; judging whether the strength of the prestressed anchor bolt meets the requirement according to the lowest tensile strength of the anchor bolt after heat treatment and the effective area of the screw thread of the anchor bolt.
Alternatively, by formula N d ＝1.35γ w N k Acquiring the strength of a prestressed anchor bolt; wherein N is d The strength of the prestressed anchor bolt is given in kN; gamma ray w Taking gamma as a working condition coefficient w ＝1.1；N k Under the standard combination of load effectThe maximum pulling force acting on a single anchor rod is standard, in kN.
Alternatively, if N d ≤0.63f u A e Determining that the strength of the prestressed anchor bolt meets the requirement, otherwise, determining that the strength of the prestressed anchor bolt does not meet the requirement; wherein f u For the lowest tensile strength of the anchor bolt after heat treatment, the anchor bolt has the following grade f of 8.8 u Taken as 830MPa, for level 10.9 f u Taking 1040MPa; a is that e Is the effective area of the screw thread of the anchor bolt, and the unit is mm 2 。
B22, checking and calculating the shearing resistance of the prestressed anchor bolt, comprising: acquiring a first friction force between a column base and a foundation; obtaining a shear resistance estimated minimum value according to a horizontal force design value and a first friction force of the bottom of the tower; acquiring a first shearing capacity of a system formed by the anchor bolts and the concrete foundation; judging whether the first shearing capacity meets the requirement or not according to the lowest value of the shearing capacity estimation.
Alternatively, the formula f=μ·p is used n Calculate the first friction force f between the toe and the foundation =0.4×1.2×n' ×p; wherein n' is the total number of anchor rods, and p is the actual pretightening force of the anchor rods.
Alternatively, by formulaAnd obtaining a shear capacity estimated minimum value V. Wherein F is r For the design value of the horizontal force at the bottom of the tower barrel, F r ＝1.5×F rk ；F rk Is the standard value of the horizontal force at the bottom of the tower. When the design value of the horizontal force of the bottom of the tower is smaller than or equal to the first friction force, the estimated minimum value V of the shearing capacity is 0, and when the design value of the horizontal force of the bottom of the tower is larger than the first friction force, the estimated minimum value V=F of the shearing capacity is at the moment r -f。
Alternatively, by formula V b ＝n`f v m A r Calculating the first shear capacity V of a system consisting of an anchor bolt and a concrete foundation b The method comprises the steps of carrying out a first treatment on the surface of the Wherein f v m The design value of the shearing strength of the anchor bolts is that n' is the total number of the anchor bolts, A r Is the cross-sectional area of the anchor bolt.
In some embodiments, the shear strength design value of the anchor bolt is the same as the shear strength design value of a conventional bolt.
Optionally, determining whether the first shear capacity meets the requirement according to the estimated minimum value of the shear capacity includes: when F r >If V is less than or equal to V in f b The first friction and the first shear capacity meet the requirements, whereas the first friction and the first shear capacity do not meet the requirements; in case the first friction and the first shear capacity do not meet the requirements, a shear key is provided.
In some embodiments, the shear capacity of a toe anchor includes a first friction between the toe and the individual foundation, and a first shear capacity of a system of anchors and concrete foundations. Assuming a coefficient of friction of 0.4 at the toe floor to concrete interface, horizontal shear forces greater than this are borne by the anchors.
B23, checking and calculating the local compressive stress, including: and (3) checking the stress in the concrete under grouting, checking the stress in high-strength grouting and checking the compressive stress of the concrete at the upper part of the lower anchor plate.
And B231, checking the stress in the concrete under grouting through the following formula, and if the following formula is satisfied, determining that the stress in the concrete under grouting meets the requirements:
wherein sigma max Sum sigma min When the load effect basic combination is adopted, the maximum compressive stress value and the minimum compressive stress value of the bottom edge of the member are calculated, F is the vertical force born by the basic bearing platform under the load effect basic combination, n' is the total number of anchor rods, p is the actual pretightening force of the anchor bolts, M is the bending moment generated by the counter force of the foundation pile and the self weight of the bearing platform on the checking section under the fatigue load effect, A is the effective section area of the annular member, W is the section resisting moment of the annular member, and F is the effective section area of the annular member c Is designed value of compressive strength of concrete axle center, beta c For the bearing platform to be subjected to the impact coefficient of the height of the section of the punching bearing capacity, beta l The strength of the concrete is increased by a factor when the concrete is locally pressed.
Alternatively, the effective cross-sectional area of the annular memberD and D are the outer and inner diameters of the calculated components, ω is the influence coefficient of the load distribution, and typically the fan foundation takes ω=1, D h Is the diameter of the anchor rod hole.
Alternatively, the cross-sectional moment-resisting of the annular member
B232, checking and calculating stress in high-strength grouting, including: and judging whether the stress in the high-strength grouting meets the requirement according to the strength improvement coefficient of the concrete when the concrete is locally pressed and the axle center compressive strength design value of plain concrete.
In some embodiments, the stress in the high strength grout isWhen sigma is max ≤ωβ l f cc When the stress in the high-strength grouting meets the requirement; f (f) cc Is the axle center compressive strength design value of plain concrete, f cc ＝0.85f c ；β l The strength of the concrete is increased by a factor when the concrete is locally pressed.
And B233, checking and calculating the compressive stress of the concrete at the upper part of the lower anchor plate, wherein the checking and calculating comprises the following steps: judging whether the maximum pressure stress value and the minimum pressure value are both pressure calculation values, if so, conforming to the requirements;
judgingIf so, the concrete compressive stress of the upper part of the lower anchor plate meets the requirement, A is the effective cross-sectional area of the annular member, p is the actual pretightening force of the anchor bolts, and n' is the total number of the anchor bolts.
B24, checking the section size of the local compression zone, namely checking the section sizes of the local compression zones of the grouted concrete and the concrete on the upper part of the bottom plate:
judgment F l ≤1.35β c β l f c A ln Whether or not it is true, if so, the cross-sectional dimensions of the local compression zone conform toThe requirements are not met if the requirements are not met; f (F) l ＝σ max ·A ln ；f c Is designed value of compressive strength of concrete axle center, beta c For the bearing platform to be subjected to the impact coefficient of the height of the section of the punching bearing capacity, beta l A is the strength improvement coefficient of the concrete when being locally pressed ln Is the local pressed clean area of the concrete.
B25 bearing capacity checking calculation of local compression area
And B251, determining a reduction coefficient alpha of the indirect steel bar to the concrete constraint. In some embodiments, the reduction coefficient α of the indirect rebar-to-concrete constraint is 1.0 when the concrete strength grade does not exceed C50, and 0.85 when the concrete strength grade is C80, otherwise α is determined by linear interpolation.
B252, determining the volume reinforcement ratio of the reinforcing meshWherein n is 1 、A s1 、l 11 The number of the steel bars of the square grid along the transverse direction, the cross-sectional area of the single steel bar, the length of the single steel bar and n 2 、A s2 、l 12 The number of the steel bars of the square grid along the longitudinal direction, the cross-sectional area of a single steel bar and the length of the single steel bar are respectively; if the grid is square, then l 11 ＝l 12 If the grid is rectangular, then l 11 And/l 12 Are not equal. A is that cor A is the cross-sectional area of the concrete core in the range of the indirect steel bar surface cor Is larger than the local pressure area A of the concrete l Its center of gravity should be the same as A l The center of gravity of the two parts is coincident, and the value is taken according to the principle of concentricity and symmetry in calculation.
B253, obtaining the local compressive load capacity improvement coefficient of the configured indirect steel bar comprises the following steps: determining the cross-sectional area of the concrete core within the surface range of the indirect reinforcing steel bar according to the calculated bottom area of the local compression; and determining the local compressive bearing capacity improvement coefficient of the indirect steel bar according to the concrete core cross-sectional area and the concrete local compressive area within the surface range of the indirect steel bar.
In some embodiments, the space is determined from the calculated bottom area of the local compressionThe cross-sectional area of the concrete core in the area of the surface of the joint bar comprises: cross-sectional area A of concrete core in the area of indirect rebar surface cor Greater than or equal to A b When A is cor The value of (A) is A b ，A b Calculate the bottom area for local compression, when A cor Less than A b When A is cor The value is unchanged, namely
Determining a local compressive load capacity improvement coefficient of the indirect steel bar according to the concrete core cross-sectional area and the concrete local compressive area in the surface range of the indirect steel bar, wherein the local compressive load capacity improvement coefficient comprises the following steps: when A is cor Is smaller than or equal to the local pressure area A of the concrete l When 1.25 times, the local compression bearing capacity of the indirect reinforcing steel bar is configured to improve by a coefficient beta cor The value is 1.0; on the contrary, beta cor The value of (2) isNamely-> A l Is a local pressure area of the concrete.
B254, judge F l ≤0.9(β c β l f c +2αρ v β cor f yv )A ln If so, the bearing capacity of the local compression area meets the requirement; wherein alpha is a reduction coefficient of indirect steel bar to concrete constraint, ρ v The reinforcement ratio beta is the volume reinforcement ratio of the reinforcement mesh cor To configure the local compressive load capacity improvement coefficient of the indirect reinforcing steel bar, f yv Is designed to be the tensile strength of indirect reinforcing steel bars, A ln Is the local pressed clean area of the concrete.
B3, checking the bearing capacity of the foundation beam section stress, wherein the checking comprises judging whether the following formula is established, and if so, determining that the bearing capacity of the foundation beam section stress meets the requirement:
in the above formula, N is the design load, and is the unit kN; e is the eccentricity of the design load from the tension steel bar, e ′ To design the eccentricity of load from the pressed steel bar, f y And f py Yield strength of the steel bar and the prestressed steel bar respectively;
A s and A ′ s The cross-sectional areas of the longitudinal non-prestressed steel bars in the tension zone and the compression zone are respectively; a is that p And A' p The cross-sectional areas of longitudinal prestressed reinforcement of the tension zone and the compression zone are respectively; h is a 0 And h ′ 0 The distance from the resultant force center of the tension steel bars to the edge of the concrete compression area and the distance from the resultant force center of the compression steel bars to the edge of the concrete tension area are respectively; a, a s A is the distance from the centroid of the section of the tension steel bar to the edge of the concrete tension zone ′ s A is the distance from the centroid of the section of the pressed steel bar to the edge of the pressed area of the concrete p For the distance from the centroid of the section of the prestressed reinforcement to the edge of the concrete tension zone, a' p Is the distance from the centroid of the section of the prestressed reinforcement to the edge of the concrete compression zone.
In some embodiments, the cross-sectional centroid represents the center of the cross-sectional pattern.
Optionally, the checking method of the independent foundation of the lattice tower further comprises checking whether the fatigue strength of the steel pipe meets the requirement according to the fatigue life of the steel pipe by using a linear damage accumulation criterion.
Based on Palmgren-Miner linear damage accumulation criterion, checking and calculating fatigue damage sum sigma D of steel pipe i Whether or not the critical value D is exceeded lim The method comprises the steps of carrying out a first treatment on the surface of the When the fatigue damage sum ΣD i Not exceeding critical value D lim When the fatigue strength is considered to be sufficient. In some embodiments, the threshold value D lim =1. Sum of fatigue damage ΣD i The calculation is performed as follows:
the accumulated damage of the steel pipe under the action of a certain fatigue load is D:
in the above formula, j represents the number of stress amplitude spectrum blocks, n i The corresponding cycle times of each fatigue stress amplitude in the stress amplitude spectrum block are expressed as known quantity; n (N) i And the fatigue life corresponding to each fatigue stress in the stress amplitude spectrum block is shown.
Sum of fatigue damage ΣD i Is the total fatigue damage of the same section under different fatigue internal forces.
Optionally, the checking method of the lattice tower independent foundation further comprises: checking the fatigue strength of the concrete according to the stress of the concrete in the corner column
C1, calculating fatigue strength f of concrete cd,fat
In this embodiment, the corrected cylinder axis compressive strength standard value f is calculated according to the core concrete constitutive model of round steel pipe concrete c ' k ：
In the above formula, ζ is a constraint effect coefficient, f ck Is the standard value of the compressive strength of the axis of the concrete cylinder.
Fatigue strength f of concrete cd,fat Calculated according to the following formula:
c2, calculating the fatigue life of the concrete according to the fatigue strength and the compressive stress of the concrete
Under the action of fatigue load, the positive stress calculation formula is as follows:
wherein M is bending moment generated by checking the section by counter force of foundation pile and self weight of bearing platform under the action of fatigue load; w is the bending resistance section modulus of the checked section.
The fatigue maximum compressive stress sigma of the concrete can be obtained through the method c,max Minimum compressive stress sigma c,min . In some embodiments, the fatigue life N of the concrete is calculated according to the fatigue strength of the concrete and the maximum compressive stress and the minimum compressive stress of the fatigue of the concrete in combination with the compressive stress fatigue curve of the concrete given by CEB-FIP MODEL 2010 3 The method is characterized by comprising the following steps:
S cd,max ＝γ sd ·σ c,max /f cd,fat
S cd,min ＝γ sd ·σ c,min /f cd,fat
in the above, S cd,max At maximum compressive stress level, S cd,min Is the minimum compressive stress level; gamma ray sd Taking 1.1 as a safety coefficient; sigma (sigma) c,max Is the maximum compressive stress of concrete fatigue, sigma c,min Is the fatigue minimum compressive stress of the concrete, when 0<S cd,min <At the time of 0.8 of the total time,
wherein:
when log N 31 Log N at a value of 8 or less 3 ＝logN 31
When log N 31 >Log n at 8 3 ＝logN 32
In the above calculation formula, when S cd,min At > 0.8, take S cd,min ＝0.8。
When calculating, the first compressive stress of the concrete and the second compressive stress of the concrete are respectively substituted into the calculation formulas to obtain two groups of different fatigue life values.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present application, and are not limiting; although the application has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the application, and are intended to be included within the scope of the appended claims and description.
Claims (10)
1. A method of designing an independent foundation for a lattice tower, comprising:
constructing a plurality of foundation pile constraint formulas according to foundation pile stress parameters based on the combined effect of the load efficiency standards of the fan tower;
and respectively designing the foundation piles and the bearing platforms according to a plurality of foundation pile constraint formulas.
2. The method of designing according to claim 1, wherein constructing a plurality of foundation pile constraint formulas based on foundation pile stress parameters comprises:
respectively constructing a first foundation pile constraint formula and a second foundation pile constraint formula according to the single-pile vertical force and the single-pile vertical bearing force characteristic value;
and constructing a third foundation pile constraint formula according to the standard value of the pulling-out resistance limit bearing capacity of the foundation pile and the self-reconstruction of the foundation pile when the single pile pulling-out force and the group pile are not integrally damaged.
3. The method of designing according to claim 2, wherein designing the foundation pile and the abutment according to the plurality of foundation pile constraint formulas, respectively, comprises:
obtaining the number of foundation piles and the size of the foundation piles according to a plurality of foundation pile constraint formulas, wherein the size of the foundation piles comprises Zhou Shenchang and an end surface of the foundation piles;
and obtaining the size of the bearing platform according to the size of the foundation pile.
4. A method of designing according to claim 3, wherein the step of obtaining the table size based on the foundation pile size comprises:
designing the size of the bearing platform based on the first bearing platform constraint condition and the second bearing platform constraint condition; the constraint condition of the first bearing platform is that the distance value between the edge of the bearing platform and the center of the foundation pile is larger than or equal to the diameter or the side length of the foundation pile; and the constraint condition of the second bearing platform is that the edge picking length of the bearing platform is larger than or equal to a first threshold value.
5. A lattice tower, comprising:
an independent foundation designed according to the design method of the lattice tower independent foundation according to any one of claims 1 to 4; the independent foundation comprises a foundation pile and a bearing platform;
the foundation connecting beam is arranged at a preset position below the top surface of the bearing platform, and adjacent bearing platforms are connected through the foundation connecting beam.
6. A method of checking a lattice tower independent foundation, based on the lattice tower of claim 5, comprising:
carrying out stress checking calculation on the part of the prestressed tendon stretching anchor plate, the prestressed anchor bolt and the section of the foundation beam; the stress checking calculation of the prestressed anchor bolt comprises the checking calculation of the strength of the prestressed anchor bolt, the checking calculation of the shearing resistance of the prestressed anchor bolt, the checking calculation of the local compressive stress, the checking calculation of the cross section size of the local compression area and the checking calculation of the bearing capacity of the local compression area.
7. The method of claim 6, wherein the locally applying a force to the tendon tensioning anchor plate comprises:
and checking whether the local stress of the prestressed tendon tensioning anchor plate meets the requirement or not according to the structural importance coefficient, the height influence coefficient of the punched bearing capacity section of the bearing platform, the strength improvement coefficient of the concrete when the concrete is locally compressed, the concrete axle center compressive strength design value and the concrete local compression clear area.
8. The method of checking as defined in claim 6, wherein the checking of the pre-stressed anchor strength comprises:
obtaining the strength of the prestressed anchor bolt according to the maximum pulling force standard value acting on the horizontal bar anchor bolt under the combination of the working condition coefficient and the load effect standard;
judging whether the strength of the prestressed anchor bolt meets the requirement according to the lowest tensile strength of the anchor bolt after heat treatment and the effective area of the screw thread of the anchor bolt.
9. The method of claim 6, wherein the checking of the load bearing capacity of the local compression zone comprises:
determining the cross-sectional area of the concrete core within the surface range of the indirect reinforcing steel bar according to the calculated bottom area of the local compression;
determining and configuring the local compressive bearing capacity improvement coefficient of the indirect steel bar according to the concrete core cross-sectional area and the concrete local compressive area within the surface range of the indirect steel bar;
and judging whether the bearing capacity of the local compression area meets the requirement according to the local compression bearing capacity improvement coefficient of the indirect reinforcing steel bars, the reduction coefficient of the indirect reinforcing steel bars to the concrete constraint and the reinforcing steel bar mesh volume reinforcing steel bar arrangement rate.
10. The method of checking as defined in claim 6, further comprising:
calculating a first fatigue life of the steel pipe according to the first positive stress of the steel pipe and the second positive stress of the steel pipe;
calculating a second fatigue life of the steel pipe according to the shear stress of the steel pipe;
and checking whether the fatigue strength of the steel pipe meets the requirement or not by using a linear damage accumulation criterion according to the first fatigue life and the second fatigue life of the steel pipe.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114396192A (en) * | 2021-12-13 | 2022-04-26 | 中国能源建设集团安徽省电力设计院有限公司 | Plug-in type concrete-filled steel tube column base for large power transmission tower and construction method thereof |
| CN117094066A (en) * | 2023-10-20 | 2023-11-21 | 中国船舶集团风电发展有限公司 | Method, device and storage medium for determining bearing capacity of tower in wind turbine generator |
| CN117473631A (en) * | 2023-12-25 | 2024-01-30 | 贵州省公路工程集团有限公司 | Method for selecting high pile cap support bearing system |
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2023
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114396192A (en) * | 2021-12-13 | 2022-04-26 | 中国能源建设集团安徽省电力设计院有限公司 | Plug-in type concrete-filled steel tube column base for large power transmission tower and construction method thereof |
| CN114396192B (en) * | 2021-12-13 | 2024-03-15 | 中国能源建设集团安徽省电力设计院有限公司 | Inserted steel tube concrete column base for large power transmission tower and construction method thereof |
| CN117094066A (en) * | 2023-10-20 | 2023-11-21 | 中国船舶集团风电发展有限公司 | Method, device and storage medium for determining bearing capacity of tower in wind turbine generator |
| CN117094066B (en) * | 2023-10-20 | 2024-01-12 | 中国船舶集团风电发展有限公司 | Method, device and storage medium for determining bearing capacity of tower in wind turbine generator |
| CN117473631A (en) * | 2023-12-25 | 2024-01-30 | 贵州省公路工程集团有限公司 | Method for selecting high pile cap support bearing system |
| CN117473631B (en) * | 2023-12-25 | 2024-03-01 | 贵州省公路工程集团有限公司 | Method for selecting high pile cap support bearing system |
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