CN114673149A - Group anchor structure for improving ductility of large-scale foundation interface and concrete parameter correction method - Google Patents

Group anchor structure for improving ductility of large-scale foundation interface and concrete parameter correction method Download PDF

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Publication number
CN114673149A
CN114673149A CN202210214892.XA CN202210214892A CN114673149A CN 114673149 A CN114673149 A CN 114673149A CN 202210214892 A CN202210214892 A CN 202210214892A CN 114673149 A CN114673149 A CN 114673149A
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anchor
concrete
bolt
foundation
anchor plate
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宁帅朋
王金昌
吴锁平
余亮
李布辉
顾章义
陶青松
汤鹏
张庆
吴勇
陈诚
杨云
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Zhejiang University ZJU
China Energy Engineering Group Jiangsu Power Design Institute Co Ltd
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Zhejiang University ZJU
China Energy Engineering Group Jiangsu Power Design Institute Co Ltd
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    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D5/00—Bulkheads, piles, or other structural elements specially adapted to foundation engineering
    • E02D5/74—Means for anchoring structural elements or bulkheads
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D15/00—Handling building or like materials for hydraulic engineering or foundations
    • E02D15/02—Handling of bulk concrete specially for foundation or hydraulic engineering purposes
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D27/00—Foundations as substructures
    • E02D27/01—Flat foundations
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D2600/00—Miscellaneous
    • E02D2600/30—Miscellaneous comprising anchoring details

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Abstract

The invention discloses a group anchor structure for improving ductility of a large-scale foundation interface and a concrete parameter correction method. The cage type truss is connected with the anchor plate by welding; the anchor plate is positioned in the middle of the X-shaped foundation shear-resistant arm and is integrated by pouring fiber concrete. The anchor bolt is positioned between the upper anchor plate and the lower anchor plate, and the anchor bolt penetrates through the high-strength anchor plate and is fixed by the nut. And simultaneously, providing a fiber concrete crack correction method, wherein the method comprises the average crack width, the average crack spacing, the short-term crack expansion coefficient and the long-term crack expansion coefficient. The invention reduces the external macroscopic cracks of the foundation and the diseases such as corrosion, frost heaving and the like caused by the external macroscopic cracks, improves the durability of the foundation and prolongs the service life of the foundation.

Description

Group anchor structure for improving ductility of large-scale foundation interface and concrete parameter correction method
Technical Field
The invention relates to a group anchor structure for improving ductility of a large foundation interface and a parameter determination method thereof, belonging to the technical field of iron tower reinforced concrete foundation structures.
Background
The crab-bolt is connected with upper portion shaft tower structure through the footing board of the tower, and the crab-bolt is connected the most common mode of being connected of basis and shaft tower structure. Because the reinforced concrete around the anchor plate has insufficient tensile strength and shearing resistance, internal cracks often appear and even extend to the surface, and the mechanical property and long-term service life of the foundation are seriously influenced.
The anchor bolts are usually designed to be equal in length, and the mechanical transmission and deformation of the anchor bolts between concrete foundations have very obvious uneven characteristics, so that the uneven distribution rule causes a stress concentration area to appear at a local position of the foundation.
The domestic structural design specification basically adopts a method for limiting the maximum crack width for a concrete crack control method. The crack width calculation formula specified in the current structural design specifications (GB50010-2010) is a semi-empirical semi-theoretical formula obtained according to comprehensive theory on the basis of a large amount of test data. The requirements of the formula on the crack width under short-term loading are too strict, and the influence of fiber action and fatigue loading and long-term effects is not considered in the specification.
Disclosure of Invention
The invention aims to solve the technical problem that the design of the existing anchor bolt causes a stress concentration area to appear at a local position of a foundation, and the invention adopts the following technical scheme in order to overcome the defect in the prior art.
The anchor group structure comprises an upper anchor plate, a lower anchor plate, an anchor bolt, a cage truss and an X-shaped foundation shear-resistant arm, wherein the upper anchor plate, the lower anchor plate, the anchor bolt, the cage truss and the X-shaped foundation shear-resistant arm form an integrated structure through pouring fiber concrete;
The upper anchor plate and the lower anchor plate are respectively positioned at the top and the bottom; an anchor bolt is arranged between the upper anchor plate and the lower anchor plate and is connected to the anchor plates through nuts;
the upper anchor plate and the lower anchor plate are respectively connected with a cage type truss, the cage type truss is positioned on the inner side of the anchor bolt, the cage type truss comprises inner side nodes, outer side nodes and truss structures, and the inner side nodes, the outer side nodes and the truss structures form a space triangular pyramid shape;
the periphery of upside anchor slab and downside anchor slab sets up the anti arm of cutting of X shape basis respectively, the anti arm of cutting of X shape basis includes upper limb arm and the low limbs arm that extends to the periphery, upper limb arm and low limbs arm present and set for the contained angle, the outer peripheral position that the crossing position of upper limb arm and low limbs arm is located the anchor slab, the end of upper limb arm and low limbs arm sets up annular boots board section respectively.
Further, the outside node of cage truss sets up the anchor bolt hole interval arrangement on the anchor slab according to the crab-bolt, and the inboard node is the anchor slab center.
Further, the crab-bolt includes the long crab-bolt in the outside and the short crab-bolt in inboard, the outside node of cage truss sets up the anchor bolt hole interval arrangement on the anchor slab according to short crab-bolt, and inboard node is the anchor slab center.
And furthermore, the outer side long anchor bolt and the inner side short anchor bolt are uniformly distributed on the anchor plate in an inner layer and an outer layer in an equal circle manner.
Furthermore, the fiber concrete adopts PVA high-toughness fibers, the volume mixing amount of the fibers is 2%, and fine aggregate concrete is adopted and uniformly mixed to play a fiber bridging role.
In a second aspect, the present invention provides a concrete parameter correction method for a group anchor structure for improving ductility of a large-scale foundation interface, which is provided by any one of the possible embodiments of the above technical solutions, and which does not consider the influence of fiber action, fatigue load and long-term effect in the current concrete crack parameter calculation method, wherein the group anchor structure for improving ductility of the large-scale foundation interface adopts the group anchor structure for improving ductility of the large-scale foundation interface provided by any one of the possible embodiments of the above technical solutions, and the parameter correction method includes:
the average crack width calculation formula is modified as follows:
Figure BDA0003532785840000021
wherein wmThe average width of the cracks is taken as the average width of the cracks,
Figure BDA0003532785840000022
is the uneven coefficient of strain, sigma, of the longitudinal tension steel bar between crackssThe longitudinal tensile steel bar stress of the reinforced concrete member is calculated according to the load quasi-permanent combination; esThe modulus of elasticity of the steel bar is,
Figure BDA0003532785840000023
for concrete strain,. lmIs the average crack spacing.
The average crack spacing was corrected to:
Figure BDA0003532785840000024
wherein C issDistance, rho, from outer edge of anchor bolt to edge of concrete in tension zone teLongitudinal reinforcement ratio, d, calculated for the effective cross-sectional area of the tensioned concreteeqThe equivalent diameter of the longitudinal reinforcement in the tension zone.
The average crack spacing in other examples was corrected to:
Figure BDA0003532785840000031
the long-term crack propagation coefficient is corrected as follows:
Figure BDA0003532785840000032
wherein a and b are material coefficients, tausShort term crack propagation coefficient.
Short term crack propagation coefficient τsThe calculation formula of (a) is as follows:
Figure BDA0003532785840000033
wherein
Figure BDA0003532785840000034
Is the mean and σ is the standard deviation.
The invention has the following beneficial technical effects:
according to the invention, the internal force distribution of the anchor bolt is improved by improving the ductile group anchor structure of the large foundation interface, and the cracking probability of the foundation can be preventively reduced or the cracking degree can be reduced by adopting the X-shaped foundation shear arm. The fiber concrete plays a role in fiber bridging, the crack resistance and the deformation capacity of a matrix are improved, and the cracking mode is improved; the cage type truss is adopted to connect the short anchor bolts and the anchor plates, so that the stress concentration of the upper concrete and the lower concrete of the anchor plates can be reduced.
In the embodiment, the anchor bolts with long and short layouts and different materials are adopted, so that the original anti-pulling mechanism can be improved, and high-performance materials can be saved.
Under the comprehensive action of the measures, the macro cracks outside the foundation and the rust frozen swelling and other diseases caused by the macro cracks are greatly reduced, the durability of the foundation is improved, and the service life of the foundation is prolonged.
Meanwhile, the invention provides a fiber concrete crack correction algorithm, considers the fiber toughening effect, the long-term crack propagation effect and the fatigue effect, and guides the basic design more reasonably through correction.
Drawings
FIG. 1 is a top view of a group anchor configuration provided in accordance with an exemplary embodiment;
FIG. 2 is an elevation view of a group anchor configuration provided by a particular embodiment;
FIG. 3 is a side view of a group anchor configuration provided by an exemplary embodiment;
FIG. 4 is a schematic illustration of a cage truss structure in a mass anchor configuration according to an exemplary embodiment;
FIG. 5 is a second schematic representation of a cage truss structure in a mass anchor configuration provided by an exemplary embodiment;
the reference numbers in the figures represent respectively: 1. foundation, 2 anchor bolts, 21 long anchor bolts, 22 short anchor bolts, 3 anchor plates, 31 upper anchor plates, 32 lower anchor plates, 4 cage type trusses, 5X-shaped foundation shear-resistant arms, 51 upper limb arms, 52 lower limb arms, 53 boot plate segments and 6 fiber concrete.
Detailed Description
The present invention will be further described with reference to the following examples.
Example (b): as shown in fig. 1, a group anchor structure for improving ductility of a large foundation interface, the group anchor structure being vertically disposed inside a foundation, comprises: anchor bolts 2, anchor plates 3 (including upper anchor plates 31 and lower anchor plates 32), cage type truss 4, X-shaped basic shear-resisting arms 5 and fiber concrete 6.
The upper anchor plate 31 and the lower anchor plate 32 are located at the top and bottom of the foundation 1 and are connected by high-strength anchor bolts 2 through nuts. The cage type truss 4 is connected with the anchor plate 3 through welding; the anchor plate 3 is positioned in the middle of the X-shaped basic shear-resisting arm 5. Anchor bolts 2, upper anchor plates 31 and lower anchor plates 32, cage type truss 4 and X-shaped foundation shear arms 5 are integrated by pouring fiber concrete 6.
In a specific embodiment, the design of the group anchor configuration specifically includes:
1) anchor bolt design
The crab-bolt includes the long crab-bolt 21 in the outside and the short crab-bolt 22 in inboard, and the preferred 42CrMo material of the long crab-bolt material in the outside, Q345 material is selected for use to the short crab-bolt material in inboard, and long crab-bolt anchoring length is not less than 35 times's bolt diameter.
And (3) according to the uplift force of the tower foundation, checking and calculating the uplift bearing capacity of the foundation bolt group according to the technical specification of overhead transmission line foundation design (DL/T5219-.
2) Structural requirements
The anchor bolt spacing should not be less than 4 times its diameter. The outer diameter of the anchor plate is controlled according to the margin of 1.5 times of the anchor bolt hole, and the thickness of the anchor plate is not less than 30 mm.
The height of the cage truss is 1m, the diameter of the upper side truss is 30mm by adopting Q235 steel, and the diameter of the lower side truss is 50mm by adopting Q345 steel. Cage truss uses space triangular pyramid as main shape, and outside node is arranged according to short anchor bolt hole interval, and inboard node is the anchor slab center. And all nodes at the top of the cage type truss are connected with the anchor plate through welding in order to improve the deformation resistance of the anchor plate and improve the concrete stress concentration near the anchor plate. Under the effect of the upper pulling load, the concrete below the upper anchor plate 31 deforms to receive larger pulling force of the anchor bolt, and the concrete in the middle of the anchor bolt deforms to be smaller along with the increase of the depth, so that bowl-shaped cracks are formed in a certain range below the upper anchor plate 31. Therefore, the upper cage truss is disposed below the upper anchor plate 31, preventing cracks from being generated in the concrete under the upper anchor plate 31 due to excessive tension. At the same time, the lower anchor plate 32 is displaced less but is stressed more, so that the concrete deformation above it is stressed more by the anchor plate, while the concrete stress and deformation in the middle of the anchor bolt are less, resulting in the formation of cracks in a certain range above the anchor plate. Therefore, the lower cage truss is disposed above the lower anchor plates 32, thereby preventing stress concentration near the upper anchor plates 31 and the lower anchor plates 32.
The length of the X-shaped basic shear-resistant arm 5 is 1m, the reinforcement is configured according to the structure of the ring beam, the main reinforcement is phi 16 hot forming steel, and the stirrup is phi 8@ 200. The X-shaped foundation shear-resistant arm adopts an annular steel reinforcement framework, the annular beam is referred for reinforcement, the whole body is provided with an upper limb 51 and a lower limb 52, the tail ends of the upper limb 51 and the lower limb 52 are boot plate sections 53, the upper limb 51, the lower limb 52 and the boot plate sections 53 are all of steel reinforcement structures, and fiber reinforced concrete external force (tensile force) is jointly formed by fiber concrete and steel reinforcements, so that the steel reinforcement stress can be effectively reduced, and the crack propagation law can be accurately predicted.
The anchor plate is easy to generate a crack propagation path in the direction of 45 degrees under the action of periodic load, so that the X-shaped shear arm is arranged at the position in advance, the stress can be propagated, and the cracking probability and the cracking degree are reduced preventively. The anchor plate is positioned in the middle of the X-shaped foundation shear-resistant arm and is rigidly connected through pouring fiber concrete.
The fiber concrete 6 adopts PVA high-toughness fibers, the volume mixing amount of the fibers is 2 percent, and fine aggregate concrete is adopted, and the fibers are uniformly mixed to play a role in bridging, so that the crack resistance of the matrix is improved, a certain tensile working range is still kept after cracking, and the traditional main crack propagation mode is changed into a multi-crack cracking mode. And in the aspects of crack resistance and construction, pouring is carried out within the range of 1 meter outside the anchor plate, vibration is enhanced, and monitoring is carried out in time.
3) Anchor plate design
In this embodiment, the outside round hole and the inboard round hole that the inside and outside two-layer isocircular set up are arranged to the annular equidistant on the anchor slab, and the crab-bolt adopts the combination form of length combination to evenly arrange, and outside long crab-bolt 21 is corresponding with the outside round hole, and inboard short crab-bolt 22 is corresponding with the inboard round hole. In the double-layer structure, the outer long anchor bolt 21 can exert a larger bending resistance, so the outer long anchor bolt is arranged in a mode of being longer at the outer side and shorter at the inner side, and the outer long anchor bolt 21 also adopts a material with higher strength to bear more mechanical transmission and bending resistance. The arrangement form can improve the mechanical distribution of the anchor bolt. Wherein the long anchor bolts 21 penetrate through the upper and lower anchor plates 32 and are fixed to the anchor plates 3 by nuts, and the short anchor bolts 22 are connected to the upper and lower anchor plates 31 and 32 by bolts, respectively.
The anchor plate is a high-strength steel plate with the thickness of 100mm, the diameter of the anchor plate is 3200mm, the distance from the center of the outer side round hole to the geometric center of the anchor plate is 1225mm, the distance from the center of the inner side round hole to the geometric center of the anchor plate is 850mm, and the diameters of the inner side round hole and the outer side round hole are 80 mm. And an inner layer and an outer layer of equal round holes are arranged at equal intervals along the annular direction. The number of the outer round holes is 24, and the number of the inner round holes is 16.
(2) Machining and mounting scheme
1) And connecting the anchor plate and the cage type truss according to the design size, and welding the truss and the anchor plate into a whole.
2) And assembling the anchor plate and the foundation bolt group into a whole.
3) And in the process of binding the foundation steel bars, fixing the whole bolt group in place. The fixing and positioning precision of the foundation bolts meets the requirements of the construction and acceptance standards of 110 kV-750 kV overhead transmission lines.
4) And binding the X-shaped foundation shear-resistant arm on site, and temporarily fixing the X-shaped foundation shear-resistant arm with the foundation bolt and the anchor plate through binding.
5) And (5) pouring the foundation fiber concrete.
The above description is only of the preferred embodiments of the present invention, and it should be noted that: it will be apparent to those skilled in the art that various modifications and adaptations can be made without departing from the principles of the invention and these are intended to be within the scope of the invention.
Based on the group anchor structure for improving the ductility of the large-scale foundation interface provided by the above embodiment, the concrete embodiment of the invention also provides a concrete parameter correction method for the group anchor structure for improving the ductility of the large-scale foundation interface, which comprises the following steps:
the long-term crack expansion coefficient and the stress characteristic coefficient alpha are correctedcrAnd also corrected accordingly.
Introducing fiber strain: generally, the average tensile strain of the steel bars far exceeds that of the concrete, so the average tensile strain of the concrete is usually ignored, but when the fibers are added into the concrete, the ductility of the concrete matrix is greatly enhanced and can reach up to 200 times of the original ductility. Therefore, the concrete strain can not be ignored, and the calculation formula of the average width of the crack is corrected to
Figure BDA0003532785840000061
wmAverage width of cracks, mm;
lmaverage crack spacing, mm.
Figure BDA0003532785840000062
The uneven coefficient of the longitudinal tension steel bar strain among the cracks;
Figure BDA0003532785840000063
ftkthe standard value of the tensile strength of the concrete axle center is obtained; rhoteThe reinforcement ratio of the longitudinal tension steel bar is calculated according to the effective section area of the tension concrete.
σsThe longitudinal tensile steel bar stress of the reinforced concrete member is calculated according to the load quasi-permanent combination; esIs the modulus of elasticity of the steel bar, N/mm2。
Figure BDA0003532785840000064
The concrete is strained.
The average crack spacing was corrected to:
Figure BDA0003532785840000071
Csdistance, mm, from the outer edge of the anchor to the edge of the concrete in the tension zone. Cs<20mm at 20mm, Cs>65mm when 65mm, and C when Cs is more than or equal to 20 and less than or equal to 65sTaking values according to actual;
ρte-longitudinal reinforcement ratio of the tensioned steel bars calculated according to the effective cross-sectional area of the tensioned concrete; rhote＝As/Ate(ii) a Wherein A issIs the section area of a common longitudinal steel bar in a tension area AteTo achieve an effective cross-sectional area of the tensioned concrete, the cross-sectional area of the member is taken for the axial tension member. When rhote<At 0.01, take ρte＝0.01；
deq-equivalent diameter of longitudinal bars of the tension zone;
the coefficients are 1.9 and 0.08 in the specification, but the anchor bolt is equivalent to a high-strength steel bar, and the coefficient should be reduced according to the research on crack width and deflection test of 500 MPa-level steel concrete flexural members under the action of long-term load.
The average crack spacing has obvious relationship with the diameter of the steel bar, the reinforcement ratio and the thickness of the concrete protective layer, and the average crack spacing and the thickness of the concrete protective layer are the same
Figure BDA0003532785840000072
Approximately in a linear relationship, again
Figure BDA0003532785840000073
Constant, mean crack spacing with CsIncreasing with increasing, also roughly linear.
The average crack spacing formula of the anchor bolt concrete foundation can be corrected according to test data, the deformation of the fiber concrete is considered according to the slip theory, and the new average crack spacing obtained through regression analysis is corrected according to the following formula, for example:
Figure BDA0003532785840000074
and (3) cyclic load correction: under the effect of long-term fatigue load, cracks can undergo initiation, propagation and fracture after the reinforced concrete is damaged. The crack development speed of the reinforced concrete surface is fast first and then slow, namely the crack is greatly influenced by early fatigue load, and the influence of the cycle number is relatively reduced after the reinforced concrete surface enters a stable stage. Therefore, the fatigue load expansion coefficient is introduced and expressed in a logarithmic mode, and the influence of the fatigue load on the cracks is reflected.
Figure BDA0003532785840000081
Figure BDA0003532785840000082
To account for the average crack spacing after cycling effects, n cyclesLoop times, N fatigue life.
a. b is the material coefficient.
And (3) correcting the long-term crack expansion coefficient and the stress characteristic coefficient:
first, calculating the short-term crack expansion coefficient and the short-term crack width
Figure BDA0003532785840000083
Divided by the short-term average crack width of the respective component
Figure BDA0003532785840000084
Obtaining a random variable
Figure BDA0003532785840000085
From the statistical distribution of the quantities, an average value is obtained
Figure BDA0003532785840000086
(e.g., 1.0), standard deviation σ (e.g., 0.498). If the short-term crack propagation coefficient is considered according to the 95% guarantee rate, the short-term crack propagation coefficient is calculated.
Figure BDA0003532785840000087
Then, according to the long-term crack width obtained by the test
Figure BDA0003532785840000088
Divided by the short-term average crack width of the respective component
Figure BDA0003532785840000089
Obtaining random variables
Figure BDA00035327858400000810
And calculating the average value a and the standard deviation b according to the statistical result. Long term crack propagation coefficient at 95% assurance rate
Figure BDA00035327858400000811
At the same time, the stress characteristic coefficient alpha of the concretecrAre also modified accordingly, i.e.
Figure BDA00035327858400000812
Wherein, taulτiIs equal to
Figure BDA0003532785840000091
α0-the coefficient of influence of the inter-crack concrete elongation on the crack width is taken to be 0.85;
beta-a coefficient related to the stress state of the member,
psi-the combined coefficient when the two expansion coefficients are multiplied, 0.9 is taken;
αcrcharacteristic coefficient of stress of component
The long-term maximum crack width of the corrected coefficients is:
Figure BDA0003532785840000092
while the present invention has been described with reference to the embodiments shown in the drawings, the present invention is not limited to the embodiments, which are illustrative and not restrictive, and it will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the invention as defined in the appended claims.

Claims (10)

1. Improve group's anchor structure of large-scale basic interface ductility, its characterized in that: the group anchor structure is vertically arranged in a foundation, and comprises an upper anchor plate, a lower anchor plate, an anchor bolt, a cage type truss and an X-shaped foundation shear-resistant arm, wherein the upper anchor plate, the lower anchor plate, the anchor bolt, the cage type truss and the X-shaped foundation shear-resistant arm form an integrated structure through pouring fiber concrete;
the upper anchor plate and the lower anchor plate are respectively positioned at the top and the bottom; an anchor bolt is arranged between the upper anchor plate and the lower anchor plate and is connected to the anchor plates through nuts;
the upper anchor plate and the lower anchor plate are respectively connected with a cage type truss, the cage type truss is positioned on the inner side of the anchor bolt, the cage type truss comprises inner side nodes, outer side nodes and a truss structure, and the inner side nodes, the outer side nodes and the truss structure form a spatial triangular pyramid shape;
the periphery of upside anchor plate and downside anchor plate sets up the anti arm of cutting of X shape basis respectively, the anti arm of cutting of X shape basis includes upper limb arm and the low limbs arm that extends to the periphery, upper limb arm and low limbs arm present and set for the contained angle, the crossing position of upper limb arm and low limbs arm is located the peripheral position on the anchor plate, the end of upper limb arm and low limbs arm sets up annular boots board section respectively.
2. The group anchor structure for improving ductility of a large foundation interface according to claim 1, wherein: the outer side nodes of the cage type truss are arranged at intervals in anchor bolt holes in the anchor plates according to anchor bolts, and the inner side nodes are the centers of the anchor plates.
3. The group anchor structure for improving ductility of a large foundation interface according to claim 1, wherein: the crab-bolt includes the long crab-bolt in outside and the short crab-bolt in inboard, cage truss's outside node sets up the anchor bolt hole interval arrangement on the anchor slab according to short crab-bolt, and inboard node is the anchor slab center.
4. Group anchor construction for improving ductility of large foundation interfaces according to claim 3, characterized in that: the long anchor bolt in the outside and the short anchor bolt in the inboard are even two-layer isocircular cloth in the anchor slab.
5. The group anchor structure for improving ductility of a large foundation interface according to claim 1, wherein: the fiber concrete adopts PVA high-toughness fibers, the volume mixing amount of the fibers is 2%, and fine aggregate concrete is adopted and uniformly mixed to play a fiber bridging role.
6. The concrete parameter correction method for the group anchor structure for improving the ductility of the large-scale foundation interface is characterized in that the group anchor structure for improving the ductility of the large-scale foundation interface adopts the group anchor structure for improving the ductility of the large-scale foundation interface according to any one of claims 1 to 5, and the parameter correction method comprises the following steps:
The average crack width calculation formula is modified as follows:
Figure FDA0003532785830000021
wherein wmThe average width of the cracks is taken as the average width of the cracks,
Figure FDA0003532785830000022
is the uneven coefficient of strain, sigma, of the longitudinal tension steel bar between crackssThe longitudinal tensile steel bar stress of the reinforced concrete member is calculated according to the load quasi-permanent combination; esThe modulus of elasticity of the steel bar is,
Figure FDA0003532785830000023
for concrete strain,. lmIs the average crack spacing.
7. The concrete parameter correction method for a group anchor structure for improving ductility of a large foundation interface according to claim 6, characterized in that the average crack spacing is corrected as follows:
Figure FDA0003532785830000024
wherein C issDistance, rho, from outer edge of anchor bolt to edge of concrete in tension zoneteLongitudinal reinforcement ratio, d, calculated for the effective cross-sectional area of the tensioned concreteeqThe equivalent diameter of the longitudinal reinforcement in the tension zone.
8. The concrete parameter correction method for a group anchor structure for improving ductility of a large foundation interface according to claim 6, characterized in that the average crack spacing is corrected as follows:
Figure FDA0003532785830000025
wherein C issDistance, rho, from outer edge of anchor bolt to edge of concrete in tension zoneteLongitudinal reinforcement ratio, d, calculated for the effective cross-sectional area of the tensioned concreteeqThe equivalent diameter of the longitudinal reinforcement in the tension zone.
9. The concrete parameter correction method for a group anchor structure for improving ductility of a large foundation interface according to claim 6, characterized in that the long-term crack growth coefficient is corrected as follows:
Figure FDA0003532785830000026
Wherein a and b are material coefficients, tausShort term crack propagation coefficient.
10. The method of claim 9, wherein the short term crack propagation coefficient τ issThe calculation formula of (a) is as follows:
Figure FDA0003532785830000031
wherein
Figure FDA0003532785830000032
Is the mean and σ is the standard deviation.
CN202210214892.XA 2022-03-04 2022-03-04 Group anchor structure for improving ductility of large-scale foundation interface and concrete parameter correction method Pending CN114673149A (en)

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