A method for calculating the horizontal bearing capacity of rigid piles with multi-layer finite stiffness beams

Abstract

The present invention discloses a method for calculating the horizontal bearing capacity of rigid piles with attached multi-layer finite stiffness beams, comprising the following steps: 1. Considering that the horizontal bearing capacity of a pile foundation is primarily composed of the horizontal bearing capacity of the pile body and the horizontal bearing capacity of the finite stiffness beam; 2. Calculating the horizontal bearing capacity characteristic values ​​of cast-in-place piles with a pile body reinforcement ratio less than ρ and not less than ρ, respectively; 3. Calculating the horizontal bearing capacity characteristic values ​​of finite stiffness beams at different locations and superimposing them to obtain the total horizontal bearing capacity characteristic value of the finite stiffness beam; and 4. Adding the horizontal bearing capacity characteristic values ​​of the pile body and the finite stiffness beam to obtain the horizontal bearing capacity of the pile foundation with the attached finite stiffness beam. The present invention is a general calculation theory for pile foundation engineering and has strong engineering applicability.

Description

Technical Field

[0001] The present invention belongs to the field of pile foundation structures, and in particular relates to a method for calculating the horizontal bearing capacity of a rigid pile with additional multi-layer finite stiffness beams, and is mainly applicable to engineering fields where pile foundations are applied, including marine engineering, bridge engineering, etc. Background Art

[0002] With my country's socioeconomic development, megaprojects are constantly emerging, often requiring high foundation bearing capacity and strict settlement control. Traditional pile foundations suffer from limitations such as low material utilization and low bearing capacity. This is particularly true for traditional foundations in thick overburden and long-span bridges, where the slenderness ratio is severely imbalanced. Therefore, innovation and application of large-scale bridge foundation forms, design theories, and construction technologies are urgently needed.

[0003] A pile foundation with an additional finite stiffness beam is a type of pile foundation structure. The calculation of the vertical bearing capacity of the pile foundation structure is the key to pile foundation design. Based on the principle of bionics, a multi-head jacking device developed in conjunction with the foundation is used to squeeze and expand the prefabricated finite stiffness beam into the surrounding soil. A horizontal reinforced concrete finite stiffness beam is "grafted" onto the foundation. The finite stiffness beam can effectively transfer the load to the soil, thereby improving the stability and bearing capacity of the foundation. During the construction of the pile foundation with an additional finite stiffness beam, holes are reserved on the prefabricated steel cage. After the steel cage is lowered, special equipment is used to push the prefabricated finite stiffness beam into the soil. Finally, the pile body concrete is poured to complete the construction of the pile foundation with an additional finite stiffness beam.

[0004] The calculation method for the vertical bearing capacity of traditional pile foundations has become mature, but as a type of foundation structure, the pile foundation with additional finite stiffness beams has not yet formed a complete practical calculation method for the horizontal bearing capacity. Summary of the Invention

[0005] In order to overcome the shortcomings of the existing technology, the present invention provides a method for calculating the horizontal bearing capacity of rigid piles with additional multi-layer finite stiffness beams, so as to determine the horizontal bearing capacity of pile foundations through parameters, which is conducive to the normalization and standardization of pile foundation design, thereby providing a theoretical basis for the horizontal bearing capacity of pile foundations and promoting the application of the pile foundation.

[0006] In order to achieve the above-mentioned object, the present invention adopts the following technical solutions:

[0007] The method for calculating the horizontal bearing capacity of a rigid pile with an additional multi-layer finite stiffness beam according to the present invention is characterized in that it comprises the following steps:

[0008] Step 1: Obtain the external load parameters of the pile foundation, including: pile top vertical load N;

[0009] Obtain the parameters of the pile foundation: the horizontal deformation coefficient α of the pile, the modulus plasticity coefficient γ of the pile section m , design value of tensile strength of pile concrete f t , the section modulus w0 of the tensile edge of the pile body conversion section, the maximum bending moment coefficient v of the pile body M , bending stiffness of pile body EI, allowable horizontal displacement of pile top x 0a , pile top horizontal displacement coefficient v X , pile reinforcement ratio ρ g , Pile body converted cross-sectional area A n , influence coefficient of vertical force on pile top ζ N and pile diameter d;

[0010] The soil parameters obtained include: the proportional coefficient m of the horizontal resistance coefficient of the soil on the pile side;

[0011] Step 2: Use formula (1) to obtain the horizontal bearing capacity characteristic value R of the pile foundation ha :

[0012]

[0013] In formula (1), ρ represents the threshold value of the pile reinforcement ratio, k1, k2, k3, and k4 are four correlation coefficients respectively;

[0014] Step 3: Based on the angle between the axis of the finite stiffness beam and the horizontal load direction, the finite stiffness beams on the same layer are divided into three categories: if the axis of the finite stiffness beam is consistent with the horizontal load direction, the finite stiffness beam is classified as category A; if the axis of the finite stiffness beam is oblique to the horizontal load direction, the finite stiffness beam is classified as category B; if the axis of the finite stiffness beam is perpendicular to the horizontal load direction, the finite stiffness beam is classified as category C;

[0015] The horizontal bearing capacity characteristic values ​​of type A, type B, and type C finite stiffness beams are calculated and recorded as R hg1 、R hg2 and R hg3 , and then the horizontal bearing capacity of the finite stiffness beam is obtained by superimposing the horizontal bearing capacity of the three types of finite stiffness beams R hg ;

[0016] Step 4: The horizontal bearing capacity characteristic value R ha and the horizontal bearing capacity R of the finite stiffness beam hg After accumulation, the horizontal bearing capacity of the pile foundation with additional finite stiffness beams is obtained.

[0017] The characteristic of the method for calculating the horizontal bearing capacity of a rigid pile with an additional multi-layer finite stiffness beam of the present invention is that the horizontal deformation coefficient α of the pile in step 1 is obtained using formula (2):

[0018]

[0019] In formula (2), m is the proportional coefficient of the horizontal soil resistance coefficient on the pile side, and b0 is the width of the pile body;

[0020] The section modulus w0 in step 1 is obtained using formula (3):

[0021]

[0022] In formula (3), d0 is the pile diameter after deducting the thickness of the protective layer, b is the side length of the rectangular section, and α E is the ratio of the elastic modulus of steel to the elastic modulus of concrete;

[0023] The maximum bending moment coefficient v of the pile body in step 1 M , pile top horizontal displacement coefficient v X It is determined by looking up the table based on the pile top constraint and the pile body converted buried depth αh;

[0024] The cross-sectional area A of the pile body in step 1 is converted n It is obtained by using formula (4):

[0025]

[0026] In step 1, the bending stiffness EI is obtained using formula (5):

[0027] EI=k5E c I0(5)

[0028] In formula (5), k5 is the fifth correlation coefficient, I0 is the converted section moment of inertia of the pile body, and:

[0029]

[0030] In step 3, the horizontal bearing capacity characteristic values ​​R of the three types of finite stiffness beams are obtained using equations (7), (8) and (9) respectively. hg1 、R hg2 and R hg3 :

[0031]

[0032]

[0033]

[0034] In formula (7), formula (8) and formula (9), θ represents the pile body rotation angle, and δ is the horizontal displacement of the pile top, L is the distance between the rotation center of the pile body and the pile top, k6 and k7 are the characteristic values ​​of the horizontal bearing capacity R hg1The two correlation coefficients and correlation coefficients, k8 and k9 are the horizontal bearing capacity characteristic values ​​R hg2 The two correlation coefficients are: r is the characteristic scale of the pile base surface. For the circular pile base surface, its characteristic scale r is the diameter; for the square pile base surface, its characteristic scale r is the side length; R is the radius of the pile foundation; φ is the angle between the axis of the finite stiffness beam and the horizontal force; k 10 、k 11 is the characteristic value of horizontal bearing capacity R hg3 Two correlation coefficients of ;

[0035] The width b0 of the pile body is the width of the pile section after deducting the thickness of the protective layer. The width b0 of the pile body when the pile section is circular is obtained using formula (10):

[0036]

[0037] In formula (10), σ represents the pile diameter threshold of the circular pile; c1, c2, and c3 are the three correlation coefficients for calculating the width b0.

[0038] The electronic device of the present invention includes a memory and a processor, and is characterized in that the memory is used to store a program that supports the processor to execute any of the rigid pile horizontal bearing capacity calculation methods, and the processor is configured to execute the program stored in the memory.

[0039] The present invention provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program executes any step of the method for calculating the horizontal bearing capacity of a rigid pile when the computer program is run by a processor.

[0040] Due to the adoption of the above technical solution, the beneficial effects achieved by the present invention are as follows:

[0041] 1. The present invention considers the reinforcement ratio of the pile body of the pile foundation with an additional finite stiffness beam. For pile foundations with different reinforcement ratios, the finite stiffness beam effect is first ignored. Referring to the "Technical Specifications for Building Pile Foundations" (JTG94-2008), the horizontal bearing capacity characteristic value of the pile body without the finite stiffness beam is obtained. The horizontal bearing capacity of the finite stiffness beam is then considered separately: the finite stiffness beams in the same layer at the same depth are divided into three categories. The three categories of finite stiffness beams are subjected to stress analysis respectively, and the horizontal bearing capacity characteristic values ​​of the three categories of finite stiffness beams are calculated. The horizontal bearing capacity of the single-layer finite stiffness beam is obtained by summing them up. The finite stiffness beams at different depths of the pile body contribute differently to the horizontal bearing capacity of the pile foundation. The total horizontal bearing capacity of the pile body finite stiffness beams is obtained by summing the horizontal bearing capacity characteristic values ​​of all finite stiffness beams. Finally, the horizontal bearing capacity of the root pile foundation is calculated by superimposing the horizontal bearing capacities of the pile body and the finite stiffness beams. Among them, the calculation parameters only include basic pile foundation, soil, load and finite stiffness beam, etc., which are all easy to obtain parameters. The vertical soil resistance calculation is a recommended calculation method for pile foundation engineering. Compared with the existing scheme, the calculation parameters and calculation theory used in the present invention are commonly used in pile foundation design, have strong engineering applicability, and the results obtained are more in line with the actual pile foundation engineering.

[0042] 2. This method for calculating horizontal bearing capacity is applicable to a range of pile foundation structures, including pile foundations with additional finite stiffness beams, sunken pipe pile foundations with additional finite stiffness beams, and caisson foundations with additional finite stiffness beams. Different pile foundation types can be selected based on varying engineering geological conditions, and pile and soil parameters can be adjusted accordingly. This theoretical calculation method has strong engineering practicality.

[0043] 3. This invention considers the variable position of the finite stiffness beam in a pile foundation with an additional finite stiffness beam, which is consistent with engineering practice. Based on different finite stiffness beam placements, characteristic values ​​of the horizontal bearing capacity of the finite stiffness beam at different depths are obtained, which has practical application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 A schematic diagram of pile deformation provided by an embodiment of the present invention;

[0045] Figure 2 A distribution diagram of finite stiffness beams of a pile foundation with additional finite stiffness beams provided in an embodiment of the present invention;

[0046] Figure 3 Flowchart of the horizontal bearing capacity calculation method of the present invention. DETAILED DESCRIPTION

[0047] In this embodiment, a method for calculating the horizontal bearing capacity of a rigid pile with an additional multi-layer finite stiffness beam is to calculate the horizontal bearing capacity characteristic values ​​of cast-in-place piles with a pile reinforcement ratio less than ρ and not less than ρ respectively based on the pile body reinforcement ratio, calculate the horizontal bearing capacity characteristic values ​​of finite stiffness beams at different positions, superimpose them to obtain the total horizontal bearing capacity characteristic value of the finite stiffness beam, and then add the horizontal bearing capacity characteristic values ​​of the pile body and the finite stiffness beam to obtain the horizontal bearing capacity of the pile foundation with the additional finite stiffness beam. Specifically, if Figure 3 As shown, the following steps are included:

[0048] Step 1: Obtain the external load parameters of the pile foundation, including the vertical load N at the top of the pile, and calculate and determine it based on actual conditions.

[0049] Obtain the parameters of the pile foundation: the horizontal deformation coefficient α of the pile, the modulus plasticity coefficient γ of the pile section m , design value of tensile strength of pile concrete f t , the section modulus w0 of the tensile edge of the pile body conversion section, the maximum bending moment coefficient v of the pile body M , bending stiffness of pile body EI, allowable horizontal displacement of pile top x 0a , pile top horizontal displacement coefficient v X , pile reinforcement ratio ρ g , Pile body converted cross-sectional area A n , influence coefficient of vertical force on pile top ζ N and pile diameter d;

[0050] The horizontal deformation coefficient α of the pile is obtained using formula (1):

[0051]

[0052] In formula (1), m is the proportional coefficient of the horizontal soil resistance coefficient on the pile side, which should be determined through a single pile horizontal static load test. When there is no static load test data, it can be obtained by looking up the table. b0 is the width of the pile body;

[0053] The width b0 of the pile body is the width of the pile section after deducting the thickness of the protective layer. The width b0 of the pile body when the pile section is circular can be obtained using formula (2):

[0054]

[0055] In formula (2), σ represents the pile diameter threshold of the circular pile; c1, c2, and c3 are three correlation coefficients for calculating the width b0; in this embodiment, σ=1 meter.

[0056] Modulus plasticity coefficient γ of the pile section m , when the pile cross section is circular, take γ m =2, when the pile cross section is rectangular, take γ m =1.75;

[0057] Design value of tensile strength of pile concrete f t It can be obtained by looking up in a table or through a concrete tensile strength test;

[0058] The section modulus w0 is obtained using formula (3):

[0059]

[0060] In formula (3), d0 is the pile diameter after deducting the thickness of the protective layer, b is the side length of the rectangular section, and α E is the ratio of the elastic modulus of steel to the elastic modulus of concrete;

[0061] Maximum bending moment coefficient of pile body v M , pile top horizontal displacement coefficient v X It is determined based on the pile top constraint and the converted buried depth of the pile body αh; the specific value can be found in the pile foundation specifications;

[0062] The bending stiffness EI is obtained using formula (4):

[0063] EI=k5E c I0 (4)

[0064] In formula (4), k5 is the fifth correlation coefficient, I0 is the converted section moment of inertia of the pile body, and:

[0065]

[0066] Allowable horizontal displacement of pile top x 0a This can be obtained by referring to the pile foundation specifications;

[0067] Pile reinforcement ratio ρ g It can be determined by the actual reinforcement situation;

[0068] Pile body converted cross-sectional area A n It is obtained by using formula (6):

[0069]

[0070] Pile top vertical force influence coefficient ζ N , take 0.5 when the pile foundation is under compression and 1.0 when it is under tension.

[0071] The soil parameters obtained include: the proportional coefficient m of the horizontal resistance coefficient of the soil on the pile side; for details, please refer to the pile foundation specification;

[0072] Step 2: Use formula (7) to obtain the horizontal bearing capacity characteristic value R of the pile foundation ha :

[0073]

[0074] In formula (7), ρ represents the threshold value of the pile reinforcement ratio, k1, k2, k3, and k4 are four correlation coefficients respectively;

[0075] Step 3: Figure 2 As shown in the figure, the finite stiffness beams of the same layer are divided into three categories according to the angle between the axis of the finite stiffness beam and the horizontal load direction. If the axis of the finite stiffness beam is consistent with the horizontal load direction, the finite stiffness beam is classified as Category A, i.e. the first category. If the axis of the finite stiffness beam is oblique to the horizontal load direction, the finite stiffness beam is classified as Category B, i.e. the second category. If the axis of the finite stiffness beam is perpendicular to the horizontal load direction, the finite stiffness beam is classified as Category C, i.e. the third category.

[0076] The horizontal bearing capacity characteristic values ​​of type A, type B, and type C finite stiffness beams are calculated and recorded as R hg1 、R hg2 and R hg3 , and then the horizontal bearing capacity of the finite stiffness beam is obtained by superimposing the horizontal bearing capacity of the three types of finite stiffness beams R hg ;

[0077] The horizontal bearing capacity characteristic values ​​R of three types of finite stiffness beams are obtained using equations (8), (9) and (10) respectively. hg1 、R hg2 and R hg3 :

[0078]

[0079]

[0080]

[0081] In formulas (8), (9) and (10), θ represents the pile body rotation angle, and like Figure 1 The figure shows the rotation of a single pile under horizontal load. δ is the horizontal displacement of the pile top, and L is the distance between the rotation center of the pile body and the pile top. L and δ can be taken as the horizontal bearing capacity characteristic value R of a single pile without an additional finite stiffness beam. ha Under load conditions, the displacement of the pile top and the position of the displacement zero point. k6 and k7 are the characteristic values ​​of the horizontal bearing capacity R hg1 The two correlation coefficients and correlation coefficients, k8 and k9 are the horizontal bearing capacity characteristic values ​​R hg2 The two correlation coefficients are: r is the characteristic scale of the pile base surface. For the circular pile base surface, its characteristic scale r is the diameter; for the square pile base surface, its characteristic scale r is the side length; R is the radius of the pile foundation; φ is the angle between the axis of the finite stiffness beam and the horizontal force; k 10 、k 11 is the characteristic value of horizontal bearing capacity R hg3 The two correlation coefficients.

[0082] Step 4: The horizontal bearing capacity characteristic value R ha and the horizontal bearing capacity R of the finite stiffness beam hg After accumulation, the horizontal bearing capacity R of the pile foundation with additional finite stiffness beam is obtained. hg =R hg1 +R hg2 +R hg3 .

[0083] In this embodiment, an electronic device includes a memory and a processor, wherein the memory is used to store a program that supports the processor to execute the above method, and the processor is configured to execute the program stored in the memory.

[0084] In this embodiment, a computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the above method are executed.

Claims

1. A method for calculating the horizontal bearing capacity of rigid piles with additional multi-layer finite stiffness beams, characterized in that: The following steps are involved: Step 1: Obtain the external load parameters of the pile foundation, including: vertical load at the top of the pile ; Obtain the parameters of the pile foundation: the horizontal deformation coefficient of the pile , Modulus plasticity coefficient of pile section , Design value of tensile strength of pile concrete , Section modulus of the tensile edge of the pile conversion section , maximum bending moment coefficient of pile body , bending stiffness of the pile body , allowable horizontal displacement of pile top , pile top horizontal displacement coefficient , Pile reinforcement ratio , Pile body converted cross-sectional area , influence coefficient of vertical force on pile top and pile diameter ; The soil parameters obtained include: the proportional coefficient of the horizontal resistance coefficient of the pile side soil ; Step 2: Use formula (1) to obtain the horizontal bearing capacity characteristic value of the pile foundation : (1) In formula (1), represents the threshold value of the pile reinforcement ratio, , , , There are four correlation coefficients respectively; Step 3: Based on the angle between the axis of the finite stiffness beam and the horizontal load direction, the finite stiffness beams on the same layer are divided into three categories: if the axis of the finite stiffness beam is consistent with the horizontal load direction, the finite stiffness beam is classified as category A; if the axis of the finite stiffness beam is oblique to the horizontal load direction, the finite stiffness beam is classified as category B; if the axis of the finite stiffness beam is perpendicular to the horizontal load direction, the finite stiffness beam is classified as category C; Using equations (7), (8) and (9), the horizontal bearing capacity characteristic values ​​of finite stiffness beams of type A, type B and type C are calculated and recorded as 、 and , and thus the horizontal bearing capacity of the finite stiffness beam is obtained by superimposing the horizontal bearing capacity of the three types of finite stiffness beams ; (7) (8) (9) In formula (7), formula (8) and formula (9), represents the pile body angle, and , is the horizontal displacement of the pile top, is the distance between the rotation center of the pile and the pile top, 、 is the characteristic value of horizontal bearing capacity The two correlation coefficients of 、 is the characteristic value of horizontal bearing capacity The two correlation coefficients of is the characteristic scale of the pile base surface. For the circular pile base surface, its characteristic scale is is the diameter. For the square pile base surface, its characteristic scale is is the side length, is the radius of the pile foundation, is the angle between the axis of the finite stiffness beam and the horizontal force, 、 is the characteristic value of horizontal bearing capacity Two correlation coefficients of Step 4: Set the horizontal bearing capacity characteristic value and the horizontal bearing capacity of a beam with finite stiffness After accumulation, the horizontal bearing capacity of the pile foundation with additional finite stiffness beams is obtained.

2. The method for calculating the horizontal bearing capacity of rigid piles for additional multi-layer finite stiffness beams according to claim 1 is characterized in that: Horizontal deformation coefficient of the pile in step 1 It is obtained by using formula (2): (2) In formula (2), is the proportional coefficient of the horizontal soil resistance coefficient on the pile side, is the width of the pile; Section modulus in step 1 It is obtained by using formula (3): (3) In formula (3), is the pile diameter after deducting the thickness of the protective layer, is the side length of the rectangular cross section, is the ratio of the elastic modulus of steel to the elastic modulus of concrete; The maximum bending moment coefficient of the pile body in step 1 , pile top horizontal displacement coefficient The buried depth is calculated based on the pile top constraint and pile body Check the table to confirm; The cross-sectional area of ​​the pile body in step 1 is converted It is obtained by using formula (4): (4) The bending stiffness in step 1 It is obtained by using formula (5): (5) In formula (5), is the fifth correlation coefficient, Convert the section moment of inertia of the pile body and have: (6)。 3. The method for calculating the horizontal bearing capacity of rigid piles for additional multi-layer finite stiffness beams according to claim 2 is characterized in that: The width of the pile is the width of the pile section after deducting the thickness of the protective layer, and the width of the pile body when the pile section is circular is obtained using formula (10): : (10) In formula (10), Indicates the pile diameter threshold for circular piles; 、 、 To calculate the width The three correlation coefficients.

4. An electronic device comprising a memory and a processor, characterized in that: The memory is used to store a program that supports the processor to execute the method for calculating the horizontal bearing capacity of a rigid pile as described in any one of claims 1 to 3, and the processor is configured to execute the program stored in the memory.

5. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method for calculating the horizontal bearing capacity of a rigid pile according to any one of claims 1 to 3 are executed.

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