A method for optimizing the pile-soil stress ratio in a solidified soil-flexible pile composite foundation considering infiltration.

Abstract

This invention discloses a method for optimizing the pile-soil stress ratio in a solidified soil-flexible pile composite foundation, considering infiltration, belonging to the technical field of foundation treatment calculation and composite foundation optimization design. This method addresses the problems in existing technologies, such as the pile side friction model not considering infiltration erosion effects, insufficient representation of the solidified soil cushion layer, and inadequate calculation accuracy. The technical solution establishes a two-segment pile side friction distribution function incorporating infiltration factors, couples the equivalent compression and deformation coordination relationship of the solidified soil cushion layer, iteratively solves for the neutral plane depth, and calculates the pile-soil vertical stress based on the load transfer method to obtain the pile-soil stress ratio. Then, parameter optimization is performed with the goal of reducing or constraining the pile-soil stress ratio. This invention improves calculation accuracy, optimizes foundation design, reduces the pile-soil stress ratio, maximizes the bearing capacity of the soil between piles, reduces pile material consumption, and is suitable for rapid engineering design and verification.

Description

Technical Field

[0001] This invention belongs to the field of foundation treatment and CO2 sequestration (carbon fixation) technology, and particularly relates to a method for optimizing the pile-soil stress ratio of solidified soil-flexible pile composite foundation considering infiltration. Background Technology

[0002] Traditional pile-composite foundations use crushed stone or sand as a cushion layer, primarily to coordinate the deformation of the piles and soil. In recent years, research on solidified soil as a cushion layer has gained traction; it, together with the piles, forms an integral composite foundation, significantly improving bearing capacity. However, existing technologies have the following drawbacks: The pile side skin friction model is simplistic: Existing studies mostly use a uniform elastoplastic model, which does not fully consider the piecewise distribution of skin friction under the characteristics of long piles and ignores the infiltration and erosion effect, resulting in large deviations in the stress calculation of long piles. The role of the solidified soil layer is not fully reflected: Although existing methods involve solidified soil, they do not systematically analyze its specific impact on pile-soil deformation coordination and stress distribution. The equivalent stiffness of the solidified soil is not included in the load transfer and coordination equations, and the calculation results do not completely match actual engineering. Insufficient accuracy: Some models do not fully consider the vertical penetration effect of the pile, affecting the accuracy of the pile-soil stress ratio. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention proposes a method for optimizing the pile-soil stress ratio in a solidified soil-flexible pile composite foundation, considering infiltration. A two-segment pile side friction model considering infiltration is established, allowing the solidified soil cushion layer to participate in the coordination process as a "stiffness channel." A closed-loop piecewise analytical solution and a neutral surface iterative process are provided to improve the pile-soil stress ratio. The accuracy of calculations and their engineering usability.

[0004] To achieve the above objectives, this invention provides a method for optimizing the pile-soil stress ratio of a solidified soil-flexible pile composite foundation, taking into account infiltration, comprising: S1. Input the design parameters of the composite foundation, including uniformly distributed load, pile length, pile diameter, pile cross-sectional area and perimeter, equivalent modulus of soil between piles and solidified soil cushion layer, cushion layer thickness, active earth pressure coefficient, upper section friction coefficient and lower section friction coefficient, and set the infiltration influence depth and infiltration weight parameters. S2. Construct an infiltration influencing factor that varies with depth to characterize the pile side friction attenuation effect caused by infiltration. S3. Based on the infiltration influencing factor and the upper and lower friction coefficients, establish a two-segment pile side friction distribution function, wherein the neutral plane is the boundary, the negative friction coefficient is used above the neutral plane, and the positive friction coefficient is used below the neutral plane. S4. Solve the neutral surface depth iteratively. The iterative process includes setting an initial value for the neutral surface depth, updating the neutral surface depth based on the deformation compatibility equation, and checking the convergence conditions until the settlement compatibility and constraint conditions are met. S5. Based on the neutral surface depth and the two-segment pile side friction distribution function, the load transfer method is used to solve the vertical stress distribution of the pile and the soil between the piles, and the pile-soil stress ratio is calculated. S6. With the goal of reducing or constraining the pile-soil stress ratio, adjust one or more of the design parameters and output the optimized parameters and pile-soil stress ratio.

[0005] Optionally, the process of inputting design parameters for the composite foundation includes: collecting uniformly distributed load, pile length, pile diameter, pile cross-sectional area, pile perimeter, equivalent modulus of soil between piles, equivalent modulus of solidified soil cushion layer, cushion layer thickness, active earth pressure coefficient, upper section friction coefficient, and lower section friction coefficient; and setting infiltration influence depth and infiltration weight parameters, wherein the infiltration weight parameter takes a value between 0 and 1, which is used to quantify the degree of weakening of pile side friction by infiltration erosion.

[0006] Optionally, the process of constructing the infiltration impact factor that varies with depth includes: defining the infiltration impact factor as a depth function, with a value between 0 and 1, and making it dimensionless with the infiltration impact depth as the scale, wherein within the infiltration impact depth, the infiltration impact factor varies linearly with depth, and outside the infiltration impact depth, it takes a value of 1.

[0007] Optionally, the process of establishing a two-segment pile side friction distribution function includes: using the neutral plane as the boundary, applying a negative friction coefficient above the neutral plane and combining it with the infiltration influence factor to correct the friction resistance, and applying a positive friction coefficient below the neutral plane and combining it with the infiltration influence factor to correct the friction resistance, thus forming a segmented continuous friction distribution function.

[0008] Optionally, the process of iteratively solving for the neutral surface depth includes: setting an initial value for the neutral surface depth within the pile length range; calculating the neutral surface function value based on the deformation compatibility equation, wherein the deformation compatibility equation is coupled with the equivalent compression of the solidified soil cushion layer; and iteratively updating the neutral surface depth until the settlement compatibility and constraint conditions are met.

[0009] Optionally, the process of solving the vertical stress distribution of the pile and the soil between the piles using the load transfer method includes: establishing the infinitesimal equilibrium equations of the pile and the soil between the piles; substituting the two-segment pile side friction distribution function into the infinitesimal equilibrium equations and performing piecewise integration with the neutral surface as the boundary; and using the closed system of equations under the overall equilibrium condition to obtain the vertical stress at the top of the pile and the top of the soil between the piles.

[0010] Optionally, the process of adjusting design parameters with the goal of reducing or constraining the pile-soil stress ratio includes: selecting at least one of pile length, pile spacing, cushion layer thickness, and equivalent modulus as design variables; and adjusting the design variables to reduce the pile-soil stress ratio or bring it into the target range, while satisfying the bearing capacity and deformation constraints.

[0011] Optionally, the deformation compatibility equation includes the equivalent compression of the solidified soil cushion layer, used to correct the coupled deformation relationship between the pile, soil, and cushion layer.

[0012] Technical advantages of this invention: This invention discloses a method for optimizing the pile-soil stress ratio in a solidified soil-flexible pile composite foundation, considering infiltration. By establishing a two-stage pile side friction model that considers infiltration and coupling it with the deformation coordination relationship of the solidified soil cushion layer, it can more accurately reflect the actual stress characteristics of the pile foundation under seepage conditions, significantly improving the calculation accuracy of the pile-soil stress ratio and making the calculation results more consistent with engineering measurements. This method can effectively reduce the pile-soil stress ratio while ensuring the bearing capacity of the foundation, fully utilizing the bearing capacity of the soil between piles, thereby reducing the material consumption of the piles and improving the economic efficiency of the project. At the same time, the model provided by this invention has strong applicability, solving the problem of large calculation deviations in traditional methods under complex hydrogeological conditions, and is suitable for rapid design and verification in engineering projects. Attached Figure Description

[0013] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a schematic flowchart illustrating a method for optimizing the pile-soil stress ratio of a solidified soil-flexible pile composite foundation, taking into account infiltration, according to an embodiment of the present invention. Detailed Implementation

[0014]

[0015] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0016] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0017] like Figure 1 As shown, this embodiment provides a method for optimizing the pile-soil stress ratio of a solidified soil-flexible pile composite foundation considering infiltration, including: S1. Input the design parameters of the composite foundation, including uniformly distributed load, pile length, pile diameter, pile cross-sectional area and perimeter, equivalent modulus of soil between piles and solidified soil cushion layer, cushion layer thickness, active earth pressure coefficient, upper section friction coefficient and lower section friction coefficient, and set the infiltration influence depth and infiltration weight parameters. S2. Construct an infiltration influencing factor that varies with depth to characterize the pile side friction attenuation effect caused by infiltration. S3. Based on the infiltration influencing factor and the upper and lower friction coefficients, establish a two-segment pile side friction distribution function, wherein the neutral plane is the boundary, the negative friction coefficient is used above the neutral plane, and the positive friction coefficient is used below the neutral plane. S4. Solve the neutral surface depth iteratively. The iterative process includes setting an initial value for the neutral surface depth, updating the neutral surface depth based on the deformation compatibility equation, and checking the convergence conditions until the settlement compatibility and constraint conditions are met. S5. Based on the neutral surface depth and the two-segment pile side friction distribution function, the load transfer method is used to solve the vertical stress distribution of the pile and the soil between the piles, and the pile-soil stress ratio is calculated. S6. With the goal of reducing or constraining the pile-soil stress ratio, adjust one or more of the design parameters and output the optimized parameters and pile-soil stress ratio.

[0018] Furthermore, the process of inputting design parameters for the composite foundation includes: collecting uniformly distributed load, pile length, pile diameter, pile cross-sectional area, pile perimeter, equivalent modulus of soil between piles, equivalent modulus of solidified soil cushion layer, cushion layer thickness, active earth pressure coefficient, upper section friction coefficient, and lower section friction coefficient; and setting infiltration influence depth and infiltration weight parameters, wherein the infiltration weight parameter takes a value between 0 and 1, which is used to quantify the degree of weakening of pile side friction by infiltration erosion.

[0019] Furthermore, the process of constructing the infiltration impact factor that varies with depth includes: defining the infiltration impact factor as a depth function, with a value between 0 and 1, and making it dimensionless with the infiltration impact depth as the scale, wherein within the infiltration impact depth, the infiltration impact factor changes linearly with depth, and outside the infiltration impact depth, it takes a value of 1.

[0020] Furthermore, the process of establishing a two-segment pile side friction distribution function includes: taking the neutral plane as the boundary, using a negative friction coefficient above the neutral plane and combining it with the infiltration influence factor to correct the friction resistance, and using a positive friction coefficient below the neutral plane and combining it with the infiltration influence factor to correct the friction resistance, thus forming a segmented continuous friction distribution function.

[0021] Furthermore, the process of iteratively solving for the neutral surface depth includes: setting an initial value for the neutral surface depth within the pile length range; calculating the neutral surface function value based on the deformation compatibility equation, wherein the deformation compatibility equation is coupled with the equivalent compression of the solidified soil cushion layer; and iteratively updating the neutral surface depth until the settlement compatibility and constraint conditions are met.

[0022] Furthermore, the process of solving the vertical stress distribution of the pile and the soil between the piles using the load transfer method includes: establishing the infinitesimal equilibrium equations of the pile and the soil between the piles; substituting the two-segment pile side friction distribution function into the infinitesimal equilibrium equations and performing piecewise integration with the neutral surface as the boundary; and using the closed system of equations under the overall equilibrium condition to obtain the vertical stress at the top of the pile and the top of the soil between the piles.

[0023] Furthermore, the process of adjusting design parameters with the goal of reducing or constraining the pile-soil stress ratio includes: selecting at least one of pile length, pile spacing, cushion layer thickness, and equivalent modulus as design variables; and adjusting the design variables to reduce the pile-soil stress ratio or bring it into the target range, while satisfying the bearing capacity and deformation constraints.

[0024] Furthermore, the deformation compatibility equation includes the equivalent compression of the solidified soil cushion layer, which is used to correct the coupled deformation relationship between the pile, soil, and cushion layer.

[0025] Specifically, the implementation process of this embodiment includes: (1) Establish a pile-soil interaction model Assuming the roadbed fill is subjected to a uniformly distributed load, and the piles and the soil between them are isotropic linear elastic bodies, only vertical compression is considered. The thickness of the pile penetrating the solidified soil layer upwards is also considered. ) and the thickness of the penetrating lower layer ( ), construct deformation coordination relationships: ; ; Among them, S1, S2, S3, and S4 represent the settlement of the top surface of the solidified soil layer, the settlement of the top surface of the pile, the settlement of the bottom surface of the soil between the piles, and the settlement of the bottom surface of the pile, respectively.

[0026] (2) Constructing a two-segment pile side friction function The pile side friction ( The frictional resistance is divided into negative frictional resistance above the neutral plane and positive frictional resistance below the neutral plane, and an intrusion influence factor is introduced. This is used to quantify the degree to which infiltration erosion weakens the pile side friction, and its value varies with depth z: ; in, For depth z Vertical stress in the soil between piles.

[0027] Within the depth of erosion influence ), The value gradually decreases with depth, indicating a weakening of the frictional resistance caused by erosion; below the depth of erosion influence ( ), =1 indicates no erosion effect. Infiltration erosion (such as surface precipitation and river water) causes water to enter the soil, increasing the water content in the pores; erosion leads to particle loss, making the soil looser and increasing the pore volume; after the soil becomes loose, the density may decrease, but the increase in water content may cause a slight change in wet density. Therefore, the infiltration weight parameter can be characterized by changes in saturation and shear strength. .

[0028] in Defined as the ratio of shear strength under the same normal stress in dry / wet conditions. In the absence of experimental data, take... As initial values ​​for engineering: slight infiltration / good drainage: 0.1–0.3; normal rainfall / soft soil: 0.3–0.6; heavy rainfall / high permeability recharge: 0.6–0.9.

[0029] Infiltration Influencing Factors : ; in: ; Its integral function : ; (3) Neutral surface depth and settlement calculation Will Elastic compressibility of soil above the neutral plane Compression of soil and below ;Will Elastic compression of piles above the neutral plane Compression of soil and below Above the neutral plane are: , ; Below the neutral plane: The deformation of the underlying layer is corrected by combining the elastic half-space settlement formula. , ; Solve using the iterative method ,step: 1) Obtain initial value ; 2) Neutral surface function

[0030] 3) Iteration: ,in The depth of the neutral surface after the (k+1)th iteration update; The depth of the neutral surface obtained in the k-th iteration; for The residual value obtained after substituting into the neutral surface function; For F in ξ= The first derivative with respect to ξ; 4) Constraints: m and ,in The absolute value of the residual; (3) Change in the depth of the neutral surface between two iterations; (4) Solving for vertical stress Using the load transfer method, the equilibrium equations of the infinitesimal element are established: ; Will Substituting into the infinitesimal equilibrium equation, we have: ,in The load is uniformly distributed on the earth's surface. definition , ,in It is the equivalent shear stiffness coefficient of the pile-soil interface above the neutral plane; It is the equivalent shear stiffness coefficient of the pile-soil interface below the neutral plane.

[0031] Above the neutral plane ( ); ; Integrating and solving, we have: , ,in This refers to the vertical stress in the soil between piles at the top surface of the cushion layer; Below the neutral plane ( ); ; Similarly, with For the lower limit integral: ,in .

[0032] From overall balance: Substitute end conditions ; = ; ; ; (5) Solution of pile-soil stress ratio ; An application example of this invention is as follows: The parameters of a certain project are as follows: Pile length L = 10 m; pile spacing 1.5 m; pile cross-sectional area =0.20 m² (diameter 0.5 m); area of ​​soil reinforcement between piles =1.80 m²; uniformly distributed load Q=100 kPa; negative friction coefficient Positive friction coefficient internal friction angle Intrusion weight parameters Infiltration affects depth Neutral surface depth: Neutral surface depth .

[0033] Step-by-step calculation: 1) Geometric constants: ,in The diameter of the pile; 2) Coefficient: ; .

[0034] 3) Infiltration integral: ; ; .

[0035] 4) Adopting the engineering friendliness index: .

[0036] 5) Pile-soil stress ratio: .

[0037] 6) Top surface stress: ; .

[0038] This invention, through a two-stage frictional resistance model and deformation coordination analysis, considers infiltration and accurately reflects the stress characteristics of the pile, resulting in calculation results that better match measured values. This invention reduces the pile-soil stress ratio, fully utilizes the bearing capacity of the soil between piles, reduces pile material usage, and improves economic efficiency. This invention also addresses the shortcomings of traditional methods under complex working conditions.

[0039] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for optimizing the pile-soil stress ratio in a solidified soil-flexible pile composite foundation considering infiltration, characterized in that, include: S1. Input the design parameters of the composite foundation, including uniformly distributed load, pile length, pile diameter, pile cross-sectional area and perimeter, equivalent modulus of soil between piles and solidified soil cushion layer, cushion layer thickness, active earth pressure coefficient, upper section friction coefficient and lower section friction coefficient, and set the infiltration influence depth and infiltration weight parameters. S2. Construct an infiltration influencing factor that varies with depth to characterize the pile side friction attenuation effect caused by infiltration. S3. Based on the infiltration influencing factor and the upper and lower friction coefficients, establish a two-segment pile side friction distribution function, wherein the neutral plane is the boundary, the negative friction coefficient is used above the neutral plane, and the positive friction coefficient is used below the neutral plane. And infiltration influencing factors are introduced. This is used to quantify the degree to which infiltration erosion weakens the pile side friction. The infiltration influence factor varies with depth z: ； in, This refers to the skin friction of the pile. , These are the negative friction coefficient and the positive friction coefficient, respectively; This is the active earth pressure coefficient; For depth Vertical stress in the soil between piles; The depth is the neutral plane depth. The length of the pile; Within the depth of erosion influence , The coefficient gradually decreases with depth, indicating a weakening of the frictional resistance caused by erosion; below the depth of erosion influence... , =1 indicates no erosion effect; Infiltration Influencing Factors : ； in, For infiltration weight parameters; The depth of infiltration is affected; Its integral function : ； S4. Solve the neutral surface depth iteratively. The iterative process includes setting an initial value for the neutral surface depth, updating the neutral surface depth based on the deformation compatibility equation, and checking the convergence conditions until the settlement compatibility and constraint conditions are met. S5. Based on the neutral surface depth and the two-segment pile side friction distribution function, the load transfer method is used to solve the vertical stress distribution of the pile and the soil between the piles, and the pile-soil stress ratio is calculated. S6. With the goal of reducing or constraining the pile-soil stress ratio, adjust one or more of the design parameters and output the optimized parameters and pile-soil stress ratio.

2. The method for optimizing the pile-soil stress ratio of a solidified soil-flexible pile composite foundation considering infiltration as described in claim 1, characterized in that, The process of inputting design parameters for composite foundations includes: collecting uniformly distributed load, pile length, pile diameter, pile cross-sectional area, pile perimeter, equivalent modulus of soil between piles, equivalent modulus of solidified soil cushion layer, cushion layer thickness, active earth pressure coefficient, upper section friction coefficient, and lower section friction coefficient; and setting infiltration influence depth and infiltration weight parameters, wherein the infiltration weight parameter takes a value between 0 and 1, which is used to quantify the degree of weakening of pile side friction by infiltration erosion.

3. The method for optimizing the pile-soil stress ratio of a solidified soil-flexible pile composite foundation considering infiltration as described in claim 1, characterized in that, The process of constructing the infiltration influence factor that varies with depth includes: defining the infiltration influence factor as a depth function, with a value between 0 and 1, and making it dimensionless with the infiltration influence depth as the scale. Within the infiltration influence depth, the infiltration influence factor changes linearly with depth, and outside the infiltration influence depth, it takes a value of 1.

4. The method for optimizing the pile-soil stress ratio of a solidified soil-flexible pile composite foundation considering infiltration as described in claim 1, characterized in that, The process of establishing a two-segment pile side friction distribution function includes: taking the neutral plane as the boundary, using a negative friction coefficient above the neutral plane and combining it with the infiltration influence factor to correct the friction resistance, and using a positive friction coefficient below the neutral plane and combining it with the infiltration influence factor to correct the friction resistance, thus forming a segmented continuous friction distribution function.

5. The method for optimizing the pile-soil stress ratio of a solidified soil-flexible pile composite foundation considering infiltration as described in claim 1, characterized in that, The process of iteratively solving for the neutral surface depth includes: setting an initial value for the neutral surface depth within the pile length range; calculating the neutral surface function value based on the deformation compatibility equation, wherein the deformation compatibility equation is coupled with the equivalent compression of the solidified soil cushion layer; and iteratively updating the neutral surface depth until the settlement compatibility and constraint conditions are met.

6. The method for optimizing the pile-soil stress ratio of a solidified soil-flexible pile composite foundation considering infiltration as described in claim 1, characterized in that, The process of solving the vertical stress distribution of the pile and the soil between the piles using the load transfer method includes: establishing the infinitesimal equilibrium equations of the pile and the soil between the piles; substituting the two-segment pile side friction distribution function into the infinitesimal equilibrium equations and performing piecewise integration with the neutral surface as the boundary; and using the closed system of equations under the overall equilibrium condition to obtain the vertical stress at the top of the pile and the top of the soil between the piles.

7. The method for optimizing the pile-soil stress ratio of a solidified soil-flexible pile composite foundation considering infiltration as described in claim 1, characterized in that, The process of adjusting design parameters with the goal of reducing or constraining the pile-soil stress ratio includes: selecting at least one of pile length, pile spacing, cushion layer thickness, and equivalent modulus as design variables; and adjusting the design variables to reduce the pile-soil stress ratio or bring it into the target range, while satisfying the bearing capacity and deformation constraints.

8. The method for optimizing the pile-soil stress ratio of a solidified soil-flexible pile composite foundation considering infiltration as described in claim 1, characterized in that, The deformation compatibility equation includes the equivalent compression of the solidified soil cushion layer, which is used to correct the coupled deformation relationship between the pile, soil, and cushion layer.

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