Method and system for determining vertical dynamic stiffness of pipe piles

Abstract

The present invention provides a method and system for determining the vertical dynamic stiffness of a pipe pile, which relates to the technical field of dynamic stiffness determination, and specifically includes: collecting the material properties, geometric properties and soil parameters of the pipe pile; performing a dynamic load test on the pipe pile, obtaining the dynamic response data of the pipe pile, and generating a dynamic response index; combining the material properties and geometric properties of the pipe pile to generate a first influence index; generating a second influence index based on soil parameters; and synthesizing the first influence index, the second influence index and the dynamic response index to generate a calculation expression for the vertical dynamic stiffness of the pipe pile. The present invention improves the design accuracy and enhances the bearing capacity and safety of the pipe pile by collecting and analyzing the material properties, geometric properties and soil parameters of the pipe pile in detail. Secondly, the natural frequency and damping ratio data provided by the dynamic load test enable a deeper understanding of the dynamic characteristics of the pipe pile and reduce the risk of structural damage.

Description

Technical Field

[0001] The invention relates to the technical field of dynamic stiffness determination, and in particular to a method and system for determining the vertical dynamic stiffness of a pipe pile. Background Art

[0002] In the field of foundation engineering, pipe piles are widely used due to their superior bearing capacity and adaptability, especially when soil conditions are complex or loads are heavy. However, traditional pipe pile design methods often rely on empirical formulas and historical data, which lack systematic analysis of specific construction environments and material properties. This design approach may not only lead to inaccurate design results, but may even fail to fully consider the dynamic response characteristics of the pile foundation in practical applications, thereby affecting the seismic performance and long-term stability of the pipe piles. In addition, the dynamic characteristics of pipe piles, such as natural frequency and damping ratio, are often not fully evaluated in the design stage, resulting in unpredictable vibration behavior and potential structural damage during construction and use.

[0003] In addition, the existing technology usually ignores the influence of soil on the dynamic response of pile foundation when evaluating the vertical dynamic stiffness of pipe piles. The physical and mechanical properties of soil, such as shear modulus and rise modulus, are directly related to the bearing capacity and deformation characteristics of pipe piles, but in many cases, these parameters have not been accurately measured and analyzed. In addition, traditional testing and analysis methods often cannot achieve a comprehensive evaluation of pile foundation performance under different geological conditions, resulting in greater risks in practical applications. This limitation not only restricts the innovation and development of foundation engineering, but also makes engineers face many uncertainties and challenges in design and construction. Therefore, there is an urgent need for a systematic and scientific evaluation method to accurately obtain the dynamic characteristics of pipe piles and soil interactions, so as to improve the safety and reliability of foundation engineering.

[0004] The above information disclosed in this Background section is only for enhancement of understanding of the background of the present disclosure and therefore it may contain information that does not constitute the prior art that is already known to one of ordinary skill in the art. Summary of the invention

[0005] The purpose of the present invention is to provide a method and system for determining the vertical dynamic stiffness of a pipe pile, so as to solve the problems raised in the above background technology.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A method and system for determining vertical dynamic stiffness of a pipe pile, the specific steps comprising:

[0008] Step 1: Collect the material properties and geometric properties of the pipe piles and soil parameters through construction site exploration, measurement and analysis; the material properties of the pipe piles include the strength data, stiffness data and density of the pipe piles, the geometric properties are the length, diameter and wall thickness of the pipe piles, and the soil parameters are the soil shear modulus, soil uplift modulus and soil layer depth;

[0009] Step 2: Perform a dynamic load test on the pipe pile to obtain dynamic response data of the pipe pile, wherein the dynamic response characteristics are the natural frequency of the pipe pile and the damping ratio of the entire vibration system, and perform a correlation analysis on the natural frequency and the damping ratio to generate a dynamic response index;

[0010] Step 3: After the collected material properties and geometric properties of the pipe pile are dimensionally processed, a first influence index is generated; after the collected soil parameters are dimensionally processed, a second influence index is generated;

[0011] Step 4: The first influence index, the second influence index and the dynamic response index are combined to generate a calculation expression for the vertical dynamic stiffness of the pile.

[0012] Furthermore, the strength data is the ratio of the mass of steel bars and the mass of concrete used in the pipe pile structure, and the stiffness data includes the average elastic modulus and average Poisson's ratio of the steel and concrete used in the pipe pile;

[0013] The specific logic for collecting intensity data is:

[0014] Obtain the total concrete mass and total steel mass used to construct the pile to be evaluated, and generate the ratio of the steel mass to the concrete mass used in the pile structure, based on the formula:

[0015]

[0016] Among them, ρ is the strength data of the pile, M g is the total steel bar mass used in the pile to be evaluated, M h Total concrete mass used for the pipe piles;

[0017] The specific logic for collecting pile stiffness data is as follows:

[0018]

[0019] Where σ is the average elastic modulus of the steel and concrete used in the pile, EM g is the average elastic modulus of the steel type used in the pile to be evaluated, EM h is the average elastic modulus of the concrete type used in the piles to be evaluated;

[0020]

[0021] Among them, τ is the average Poisson's ratio of steel and concrete used in the pile, PR g is the average Poisson’s ratio of the steel type used in the pile to be evaluated, PR h is the average Poisson's ratio of the concrete type used in the piles to be evaluated;

[0022] The density N, length Len, diameter Dia and wall thickness Thi of the pipe pile are obtained according to the pipe pile design drawings.

[0023] Furthermore, the specific logic for collecting soil shear modulus is as follows: a certain volume of undisturbed soil sample is collected from the site, prepared into a standard specimen, the specimen is placed in a uniaxial compression testing machine, axial load is gradually applied, stress and strain are measured, and a stress-strain curve is plotted. The elastic modulus E of the soil is obtained from the linear part of the stress-strain curve, i.e., the initial slope. p ;

[0024] A certain volume of undisturbed soil sample is collected from the site and prepared into a standard specimen. The specimen is placed in a uniaxial compression testing machine. During the compression process, the axial deformation and lateral deformation are measured, and the Poisson's ratio of the soil is calculated according to the following formula:

[0025]

[0026] Where v is the Poisson's ratio of the soil, ε l is the transverse strain, ε a is the axial strain;

[0027] Axial strain ε a It is the ratio of the deformation along the load direction to the original length, and the calculation formula is:

[0028]

[0029] Among them, ε a is the axial strain, ΔL is the axial deformation, i.e. the length after deformation minus the original length; L0 is the original length along the load direction;

[0030] Transverse strain is the ratio of the deformation perpendicular to the load direction to the original length, and the calculation formula is:

[0031]

[0032] Among them, ε l is the transverse strain, ΔD is the transverse deformation, i.e. the length after deformation minus the original length; D0 is the original length perpendicular to the load direction;

[0033] The shear modulus G of the soil is calculated using the following formula:

[0034]

[0035] Where G is the shear modulus of the soil, E p is the elastic modulus of the soil, v is the Poisson’s ratio of the soil;

[0036] Collect soil rise modulus E n The specific logic is:

[0037] E n =3G(1-2v)

[0038] Among them, E n is the uplift modulus of soil, G is the shear modulus of soil, and v is the Poisson’s ratio of soil;

[0039] The specific logic for collecting soil depth is:

[0040] The soil layer depth is obtained by accumulating the thickness of each sub-soil layer. The calculation formula for the soil layer depth is:

[0041]

[0042] Among them, D n is the depth of the soil layer, which is the sum of the thickness of each sub-soil layer, h i is the thickness of the ith sub-layer, i is the index of the sub-layer, and i∈[1,n], n is the number of sub-layers.

[0043] Furthermore, the specific logic for collecting the natural frequency of the pipe pile is:

[0044] Install the accelerometer on the top of the pile to ensure good contact between the accelerometer and the pile body. Use vibration equipment to apply continuous dynamic load to the pile and record the time domain signal output by the accelerometer in real time. Use fast Fourier transform to extract the frequency characteristics from the time domain signal and find the frequency with the largest amplitude, which is the natural frequency f of the pile. n .

[0045] The vibration system refers to a complete structural system including the pipe pile and the surrounding soil. The damping ratio of the entire vibration system is collected based on the following specific logic: an impact load is applied to the pipe pile, and then its free vibration response is recorded. The vibration signal is recorded using an accelerometer, and the vibration signal is analyzed to observe the attenuation of the vibration amplitude over time. The damping ratio is calculated by calculating the amplitude ratio of adjacent peaks:

[0046]

[0047] in, is the damping ratio, A k and A k+1 is the amplitude of two adjacent peaks;

[0048] The formula for generating the dynamic response index is as follows:

[0049]

[0050] Where CS is the dynamic response index, f n is the natural frequency of the pile, c is the preset proportional coefficient, is the damping ratio, d is its preset proportional coefficient, and c>d>0, C1 is the first constant correction index.

[0051] Furthermore, the formula for generating the first impact index is:

[0052]

[0053] Among them, AS is the first influence index, ρ is the strength data of the pipe pile, σ is the average elastic modulus of the steel and concrete used in the pipe pile, τ is the average Poisson's ratio of the steel and concrete used in the pipe pile, N is the pipe pile density, Dia is the pipe pile diameter, Thi is the pipe pile wall thickness, Len is the pipe pile length, and C2 is the second constant correction index.

[0054] Furthermore, the formula for generating the second impact index is as follows:

[0055] BS=a*(G+E n )+b*D n +C3

[0056] Among them, BS is the second impact index, G is the soil shear modulus, E is n is the soil elevation modulus, a is the preset proportional coefficient, D n is the soil layer depth, b is its preset proportional coefficient, and a>b>0, C3 is the third constant correction exponent.

[0057] Furthermore, the vertical dynamic stiffness of the pile is determined according to the following formula:

[0058]

[0059] Among them, K is the vertical dynamic stiffness of the pile, AS is the first influence index, BS is the second influence index, CS is the dynamic response index, and C4 is the fourth constant correction index.

[0060] The present invention further provides a system for determining the vertical dynamic stiffness of a pipe pile, wherein the system is used to execute the above-mentioned method for determining the vertical dynamic stiffness of a pipe pile, and comprises:

[0061] The data acquisition module collects the material properties and geometric properties of the pipe piles and soil parameters through construction site exploration, measurement and analysis; the material properties of the pipe piles include the strength data, stiffness data and density of the pipe piles, the geometric properties are the length, diameter and wall thickness of the pipe piles, and the soil parameters are the soil shear modulus, soil uplift modulus and soil layer depth;

[0062] The data processing module performs a dynamic load test on the pipe pile to obtain the dynamic response data of the pipe pile, wherein the dynamic response characteristics are the natural frequency of the pipe pile and the damping ratio of the entire vibration system, and performs a correlation analysis on the natural frequency and the damping ratio to generate a dynamic response index;

[0063] The index generation module generates a first impact index after dimensionally processing the collected pipe pile material properties and geometric properties; and generates a second impact index after dimensionally processing the collected soil parameters;

[0064] The vertical dynamic stiffness determination module combines the first influence index, the second influence index and the dynamic response index to determine the vertical dynamic stiffness of the pipe pile.

[0065] Compared with the prior art, the present invention has the following beneficial effects:

[0066] The present invention improves the design accuracy and enhances the bearing capacity and safety of pipe piles by collecting and analyzing the material properties, geometric properties and soil parameters of pipe piles in detail. Secondly, the natural frequency and damping ratio data provided by the dynamic load test enable a deeper understanding of the dynamic characteristics of pipe piles and reduce the risk of structural damage. At the same time, the generated first influence index, second influence index and dynamic response index realize a comprehensive evaluation of dynamic stiffness and improve the adaptability and comparability of the design. In addition, this method provides important reference data for subsequent construction and maintenance, enabling engineers to effectively monitor the long-term performance of pipe piles. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] Figure 1 It is a schematic diagram of the overall method flow of the present invention;

[0068] Figure 2 It is a schematic diagram of the overall system module of the present invention. DETAILED DESCRIPTION

[0069] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments.

[0070] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the present invention should be understood by people with ordinary skills in the field to which the present invention belongs. The words "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0071] Example:

[0072] See also Figure 1 , the present invention provides a technical solution:

[0073] The method for determining the vertical dynamic stiffness of a pipe pile includes the following specific steps:

[0074] Step 1: Collect the material properties and geometric properties of the pipe piles and soil parameters through construction site exploration, measurement and analysis; the material properties of the pipe piles include the strength data, stiffness data and density of the pipe piles, the geometric properties are the length, diameter and wall thickness of the pipe piles, and the soil parameters are the soil shear modulus, soil uplift modulus and soil layer depth;

[0075] In this embodiment, the strength data is the ratio of the mass of steel bars and the mass of concrete used in the pipe pile structure, and the stiffness data includes the average elastic modulus and average Poisson's ratio of the steel and concrete used in the pipe pile;

[0076] The specific logic for collecting intensity data is:

[0077] Obtain the total concrete mass and total steel mass used to construct the pile to be evaluated, and generate the ratio of the steel mass to the concrete mass used in the pile structure, based on the formula:

[0078]

[0079] Among them, ρ is the strength data of the pile, M g is the total steel bar mass used in the pile to be evaluated, M h Total concrete mass used for the pipe piles;

[0080] The specific logic for collecting pile stiffness data is as follows:

[0081]

[0082] Where σ is the average elastic modulus of the steel and concrete used in the pile, EM g is the average elastic modulus of the steel type used in the pile to be evaluated, EM h is the average elastic modulus of the concrete type used in the piles to be evaluated;

[0083]

[0084] Among them, τ is the average Poisson's ratio of steel and concrete used in the pile, PR g is the average Poisson’s ratio of the steel type used in the pile to be evaluated, PR h The average Poisson's ratio of the concrete type used in the evaluated piles; the smaller the Poisson's ratio, the smaller the lateral strain of the material when subjected to stress, and the correspondingly larger the longitudinal strain. In the pile structure, the smaller the Poisson's ratio of the material, the more it tends to maintain its shape when subjected to stress, and is less likely to deform, which can increase the overall stiffness of the pile.

[0085] The quality of the steel bars and concrete used in the pipe piles can be obtained by referring to the design documents and structural design drawings of the pipe piles, and the elastic modulus and Poisson's ratio of the steel and concrete used can be obtained by referring to the material manual and database.

[0086] The density N, length Len, diameter Dia and wall thickness Thi of the pipe pile are obtained according to the pipe pile design drawings.

[0087] The specific logic for collecting soil shear modulus is as follows: a certain volume of undisturbed soil sample is collected from the site, prepared into a standard specimen, the specimen is placed in a uniaxial compression testing machine, axial load is gradually applied, stress and strain are measured, and a stress-strain curve is plotted. The elastic modulus E of the soil is obtained from the linear part of the stress-strain curve, i.e., the initial slope. p ;

[0088] A certain volume of undisturbed soil sample is collected from the site and prepared into a standard specimen. The specimen is placed in a uniaxial compression testing machine. During the compression process, the axial deformation and lateral deformation are measured, and the Poisson's ratio of the soil is calculated according to the following formula:

[0089]

[0090] Where v is the Poisson's ratio of the soil, ε l is the transverse strain, ε a is the axial strain;

[0091] Axial strain ε a It is the ratio of the deformation along the load direction to the original length, and the calculation formula is:

[0092]

[0093] Among them, ε a is the axial strain, ΔL is the axial deformation, i.e. the length after deformation minus the original length; L0 is the original length along the load direction;

[0094] Transverse strain is the ratio of the deformation perpendicular to the load direction to the original length, and the calculation formula is:

[0095]

[0096] Among them, ε l is the transverse strain, ΔD is the transverse deformation, i.e. the length after deformation minus the original length; D0 is the original length perpendicular to the load direction;

[0097] The shear modulus G of the soil is calculated using the following formula:

[0098]

[0099] Where G is the shear modulus of the soil, E p is the elastic modulus of the soil, v is the Poisson’s ratio of the soil;

[0100] Collect soil rise modulus E n The specific logic is:

[0101] E n =3G(1-2V)

[0102] Among them, E n is the uplift modulus of soil, G is the shear modulus of soil, and v is the Poisson’s ratio of soil;

[0103] The specific logic for collecting soil depth is:

[0104] The soil layer depth is obtained by accumulating the thickness of each sub-soil layer. The calculation formula for the soil layer depth is:

[0105]

[0106] Among them, D n is the depth of the soil layer, which is the sum of the thickness of each sub-soil layer, h i is the thickness of the ith sub-layer, i is the index of the sub-layer, and i∈[1,n], n is the number of sub-layers.

[0107] Through on-site exploration and measurement, the material and soil parameters obtained are more representative, reducing the uncertainty caused by the use of general assumptions or historical data; by comprehensively collecting different types of data, a solid foundation is laid for subsequent dynamic load tests and dynamic stiffness assessments, making subsequent analysis more credible. In this patent solution, the use of this step not only improves the scientificity and practicality of the overall solution, but also provides important support for subsequent dynamic response analysis and dynamic stiffness calculations, effectively promoting the comprehensive performance of pipe pile design and assessment.

[0108] Step 2: Perform a dynamic load test on the pipe pile to obtain dynamic response data of the pipe pile, wherein the dynamic response characteristics are the natural frequency of the pipe pile and the damping ratio of the entire vibration system, and perform a correlation analysis on the natural frequency and the damping ratio to generate a dynamic response index;

[0109] In this embodiment, the specific logic for collecting the natural frequency of the pipe pile is:

[0110] Install the accelerometer on the top of the pile to ensure good contact between the accelerometer and the pile body. Use vibration equipment to apply continuous dynamic load to the pile and record the time domain signal output by the accelerometer in real time. Use fast Fourier transform to extract the frequency characteristics from the time domain signal and find the frequency with the largest amplitude, which is the natural frequency f of the pile. n .

[0111] The vibration system refers to a complete structural system including the pipe pile and the surrounding soil. The damping ratio of the entire vibration system is collected based on the following specific logic: an impact load is applied to the pipe pile, and then its free vibration response is recorded. The vibration signal is recorded using an accelerometer, and the vibration signal is analyzed to observe the attenuation of the vibration amplitude over time. The damping ratio is calculated by calculating the amplitude ratio of adjacent peaks:

[0112]

[0113] in, is the damping ratio, A k and A k+1 is the amplitude of two adjacent peaks;

[0114] The formula for generating the dynamic response index is as follows:

[0115]

[0116] Where CS is the dynamic response index, f n is the natural frequency of the pile, c is the preset proportional coefficient, is the damping ratio, d is its preset proportional coefficient, and c>d>0. This is because the natural frequency directly reflects the stiffness characteristics of the system, while the damping ratio mainly affects the characteristics of the dynamic response and energy dissipation. Comprehensive consideration of these two parameters can more comprehensively evaluate the dynamic performance of the pile, but in terms of the direct impact of stiffness, the natural frequency is more critical; C1 is the first constant correction index; when f n When it increases, it indicates that the structure has stronger stiffness in the vertical direction, which is beneficial to the bearing capacity and seismic performance, so the dynamic response index CS increases; when When f increases, that is, the damping ratio increases, the system's response when subjected to dynamic load decays faster. A high damping ratio can reduce the duration of vibration and reduce potential damage to the structure. Therefore, the dynamic response index CS increases; that is, it indicates that f n , It is positively correlated with the dynamic response index CS.

[0117] This step obtains dynamic response data by conducting dynamic load tests on pipe piles. Its advantage is that it can directly reflect the vibration characteristics of pipe piles under actual use conditions. Compared with the prior art, this step has the following beneficial effects: through dynamic load tests, the true response of pipe piles under dynamic conditions can be obtained, providing a more accurate design basis, overcoming the shortcomings of traditional methods that rely on theoretical derivation or assumptions; scientific evaluation of dynamic characteristics: correlation analysis of natural frequency and damping ratio can reveal the interactive characteristics of pipe piles and their surrounding soil, helping designers to better understand the dynamic behavior of pipe piles and ensure safety under dynamic loads such as earthquakes. In this patent solution, the use of this step can significantly improve the dynamic performance evaluation capability of the overall solution, making the design of pipe piles more targeted and effective.

[0118] Step 3: After the collected material properties and geometric properties of the pipe pile are dimensionally processed, a first influence index is generated; after the collected soil parameters are dimensionally processed, a second influence index is generated;

[0119] In this embodiment, the formula for generating the first impact index is:

[0120]

[0121] Among them, AS is the first influence index, ρ is the strength data of the pipe pile, σ is the average elastic modulus of the steel and concrete used in the pipe pile, τ is the average Poisson's ratio of the steel and concrete used in the pipe pile, N is the density of the pipe pile, Dia is the diameter of the pipe pile, Thi is the wall thickness of the pipe pile, Len is the length of the pipe pile, and C2 is the second constant correction index; when ρ or σ increases, it means that the stiffness of the pipe pile is greater and the structure of the pipe pile is stronger, so the first influence index AS increases; when τ increases, it means that the Poisson's ratio of the material is larger, which means that it is more likely to deform when subjected to force, so AS decreases; increasing the density of the pipe pile will improve its quality, Thereby affecting the natural frequency and vibration characteristics, it can provide higher dynamic stiffness; the larger the diameter of the pipe pile, the larger its cross-sectional area, thereby enhancing the bending and compression resistance of the pipe pile, resulting in higher dynamic stiffness; increasing the wall thickness will enhance the stiffness of the pipe pile and reduce its deformation under dynamic load. The thicker wall can improve the bending and compression resistance of the pipe pile, thereby increasing the vertical dynamic stiffness; the longer pipe pile is more likely to bend during vibration, thereby reducing its vertical dynamic stiffness; that is, ρ, σ, N, Dia, Thi and the first influence index AS are positively correlated, and τ, Len and the first influence index AS are negatively correlated.

[0122] The formula for generating the second impact index is:

[0123] BS=a*(G+En)+b*D n +C3

[0124] Among them, BS is the second impact index, G is the soil shear modulus, E is n is the soil elevation modulus, a is the preset proportional coefficient, D n is the depth of the soil layer, b is its preset proportional coefficient, and a>b>0, because the modulus of the soil directly affects the interaction between the pipe pile and the soil. A higher modulus means that the soil can more effectively resist the vertical deformation of the pile, thereby providing a greater vertical dynamic stiffness; C3 is the third constant correction exponent; when the shear modulus of the soil increases, the interaction between the pipe pile and the soil is enhanced, thereby increasing the vertical dynamic stiffness of the pipe pile; the elevation modulus describes the deformation characteristics of the soil under the action of vertical loads. The increase in the elevation modulus means that the soil's resistance to vertical loads is enhanced, thereby increasing the vertical dynamic stiffness of the pipe pile; with the increase in the depth of the soil, the density of the soil will change, and deep soils often have higher consolidation and better mechanical properties, which are helpful to improve the bearing capacity and dynamic stiffness of the pipe pile; that is, G, E n , D n It is positively correlated with the second impact index BS.

[0125] Step 4: The first influence index, the second influence index and the dynamic response index are integrated to generate a calculation expression for the vertical dynamic stiffness of the pile;

[0126] In this embodiment, the vertical dynamic stiffness of the pile is determined according to the following formula:

[0127]

[0128] Among them, K is the vertical dynamic stiffness of the pile, AS is the first influence index, BS is the second influence index, CS is the dynamic response index, and C4 is the fourth constant correction index; when AS increases, the vertical dynamic stiffness K of the pile increases accordingly, when BS increases, the vertical dynamic stiffness K of the pile increases accordingly, and when CS increases, the vertical dynamic stiffness K of the pile increases accordingly; that is, AS, BS, CS and the vertical dynamic stiffness K of the pile are positively correlated.

[0129] See also Figure 2 The present invention also provides a system for determining the vertical dynamic stiffness of a pipe pile, comprising:

[0130] The data acquisition module collects the material properties and geometric properties of the pipe piles and soil parameters through construction site exploration, measurement and analysis; the material properties of the pipe piles include the strength data, stiffness data and density of the pipe piles, the geometric properties are the length, diameter and wall thickness of the pipe piles, and the soil parameters are the soil shear modulus, soil uplift modulus and soil layer depth;

[0131] The data processing module performs a dynamic load test on the pipe pile to obtain the dynamic response data of the pipe pile, wherein the dynamic response characteristics are the natural frequency of the pipe pile and the damping ratio of the entire vibration system, and performs a correlation analysis on the natural frequency and the damping ratio to generate a dynamic response index;

[0132] The index generation module generates a first impact index after dimensionally processing the collected pipe pile material properties and geometric properties; and generates a second impact index after dimensionally processing the collected soil parameters;

[0133] The vertical dynamic stiffness determination module combines the first influence index, the second influence index and the dynamic response index to determine the vertical dynamic stiffness of the pipe pile.

[0134] The specific values ​​of a, b, c and d in the formula are generally determined by technical personnel in this field according to actual conditions. The technical personnel in this field collect multiple groups of sample data, and set corresponding preset proportional coefficients for each group of sample data. The preset proportional coefficients and the collected sample data are substituted into the formula. Through repeated experiments and parameter adjustments, the accuracy of the model output and the rationality of the results are observed, and these factor coefficients are gradually adjusted. The performance and effect of the model under different parameter settings are compared to find the optimal coefficient combination, and the calculated factor coefficients are screened and averaged to obtain the values ​​of a, b, c and d.

[0135] In addition, the size of the preset factor coefficient is to quantify each parameter to obtain a specific value. In order to facilitate subsequent comparison, the size of the coefficient depends on the amount of sample data and the preset proportional coefficient initially set by technical personnel in this field for each set of sample data. It is not unique as long as it does not affect the proportional relationship between the parameter and the quantized value.

[0136] The above formulas are all dimensionless and numerical calculations. The formula is a formula for the most recent real situation obtained by collecting a large amount of data and performing software simulation. The preset parameters in the formula are set by technicians in this field according to actual conditions.

[0137] The above embodiments may be implemented in whole or in part by software, hardware, firmware or any other combination thereof. When implemented by software, the above embodiments may be implemented in whole or in part in the form of a computer program product. Those skilled in the art may appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein may be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed by hardware or software methods depends on the specific application and design constraints of the technical solution.

[0138] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, and may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0139] The above description is only a specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application.

Claims

1. A method for determining the vertical dynamic stiffness of a pipe pile, characterized in that: The specific steps include: Step 1: Collect the material properties and geometric properties of the pipe piles and soil parameters through construction site exploration, measurement and analysis; the material properties of the pipe piles include the strength data, stiffness data and density of the pipe piles, the geometric properties are the length, diameter and wall thickness of the pipe piles, and the soil parameters are the soil shear modulus, soil uplift modulus and soil layer depth; Step 2: Perform a dynamic load test on the pipe pile to obtain dynamic response data of the pipe pile, wherein the dynamic response characteristics are the natural frequency of the pipe pile and the damping ratio of the entire vibration system, and perform a correlation analysis on the natural frequency and the damping ratio to generate a dynamic response index; Step 3: After the collected material properties and geometric properties of the pipe pile are dimensionally processed, a first influence index is generated; after the collected soil parameters are dimensionally processed, a second influence index is generated; Step 4: The first influence index, the second influence index and the dynamic response index are integrated to generate a calculation expression for the vertical dynamic stiffness of the pile; The specific logic for collecting the natural frequency of the pipe pile is: Install the accelerometer on the top of the pile to ensure good contact between the accelerometer and the pile body. Use vibration equipment to apply continuous dynamic load to the pile and record the time domain signal output by the accelerometer in real time. Use fast Fourier transform to extract the frequency characteristics from the time domain signal and find the frequency with the largest amplitude, which is the natural frequency f of the pile. n ; The vibration system refers to a complete structural system including the pipe pile and the surrounding soil. The damping ratio of the entire vibration system is collected based on the following specific logic: an impact load is applied to the pipe pile, and then its free vibration response is recorded. The vibration signal is recorded using an accelerometer, and the vibration signal is analyzed to observe the attenuation of the vibration amplitude over time. The damping ratio is calculated by calculating the amplitude ratio of adjacent peaks: in, is the damping ratio, A k and A k+1 is the amplitude of two adjacent peaks; The formula for generating the dynamic response index is as follows: Where CS is the dynamic response index, f n is the natural frequency of the pile, c is the preset proportional coefficient, is the damping ratio, d is its preset proportional coefficient, and c>d>0, C1 is the first constant correction index; The formula for generating the first impact index is: Among them, AS is the first influence index, ρ is the strength data of the pipe pile, σ is the average elastic modulus of the steel and concrete used in the pipe pile, τ is the average Poisson's ratio of the steel and concrete used in the pipe pile, N is the density of the pipe pile, Dia is the diameter of the pipe pile, Thi is the wall thickness of the pipe pile, Len is the length of the pipe pile, and C2 is the second constant correction index; The formula for generating the second impact index is: BS=a*(G+E n )+b*D n +C3 Among them, BS is the second impact index, G is the soil shear modulus, E is n is the soil elevation modulus, a is the preset proportional coefficient, D n is the soil layer depth, b is its preset proportional coefficient, and a>b>0, C3 is the third constant correction index; The vertical dynamic stiffness of the pile is determined according to the following formula: Among them, K is the vertical dynamic stiffness of the pile, AS is the first influence index, BS is the second influence index, CS is the dynamic response index, and C4 is the fourth constant correction index.

2. The method for determining the vertical dynamic stiffness of a pipe pile according to claim 1, characterized in that: The strength data is the ratio of the mass of steel bars and the mass of concrete used in the pipe pile structure, and the stiffness data includes the average elastic modulus and average Poisson's ratio of the steel and concrete used in the pipe pile; The specific logic for collecting intensity data is: Obtain the total concrete mass and total steel mass used to construct the pile to be evaluated, and generate the ratio of the steel mass to the concrete mass used in the pile structure, based on the formula: Among them, ρ is the strength data of the pile, M g is the total steel bar mass used in the pile to be evaluated, M h Total concrete mass used for the pipe piles; The specific logic for collecting pile stiffness data is as follows: Where σ is the average elastic modulus of the steel and concrete used in the pile, EM g is the average elastic modulus of the steel type used in the pile to be evaluated, EM h is the average elastic modulus of the concrete type used in the piles to be evaluated; Among them, τ is the average Poisson's ratio of steel and concrete used in the pile, PR g is the average Poisson’s ratio of the steel type used in the pile to be evaluated, PR h is the average Poisson's ratio of the concrete type used in the piles to be evaluated; The density N, length Len, diameter Dia and wall thickness Thi of the pipe pile are obtained according to the pipe pile design drawings.

3. The method for determining the vertical dynamic stiffness of a pipe pile according to claim 1, characterized in that: The specific logic for collecting soil shear modulus is as follows: a certain volume of undisturbed soil sample is collected from the site, prepared into a standard specimen, the specimen is placed in a uniaxial compression testing machine, axial load is gradually applied, stress and strain are measured, and a stress-strain curve is plotted. The elastic modulus E of the soil is obtained from the linear part of the stress-strain curve, i.e., the initial slope. p ; A certain volume of undisturbed soil sample is collected from the site and prepared into a standard specimen. The specimen is placed in a uniaxial compression testing machine. During the compression process, the axial deformation and lateral deformation are measured, and the Poisson's ratio of the soil is calculated according to the following formula: Where v is the Poisson's ratio of the soil, ε l is the transverse strain, ε a is the axial strain; Axial strain ε a It is the ratio of the deformation along the load direction to the original length, and the calculation formula is: Among them, ε a is the axial strain, ΔL is the axial deformation, i.e. the length after deformation minus the original length; L0 is the original length along the load direction; Transverse strain is the ratio of the deformation perpendicular to the load direction to the original length, and the calculation formula is: Among them, ε l is the transverse strain, ΔD is the transverse deformation, i.e. the length after deformation minus the original length; D0 is the original length perpendicular to the load direction; The shear modulus G of the soil is calculated using the following formula: Where G is the shear modulus of the soil, E p is the elastic modulus of the soil, v is the Poisson’s ratio of the soil; Collect soil rise modulus E n The specific logic is: E n =3G(1-2v) Among them, E n is the uplift modulus of soil, G is the shear modulus of soil, and v is the Poisson’s ratio of soil; The specific logic for collecting soil depth is: The soil layer depth is obtained by accumulating the thickness of each sub-soil layer. The calculation formula for the soil layer depth is: Among them, D n is the depth of the soil layer, which is the sum of the thickness of each sub-soil layer, h i is the thickness of the ith sub-layer, i is the index of the sub-layer, and i∈[1,n], n is the number of sub-layers.

4. The vertical dynamic stiffness determination system of the pipe pile is characterized by: The pipe pile vertical dynamic stiffness determination system is used to execute the pipe pile vertical dynamic stiffness determination method according to any one of claims 1 to 3, comprising: The data acquisition module collects the material properties and geometric properties of the pipe piles and soil parameters through construction site exploration, measurement and analysis; the material properties of the pipe piles include the strength data, stiffness data and density of the pipe piles, the geometric properties are the length, diameter and wall thickness of the pipe piles, and the soil parameters are the soil shear modulus, soil uplift modulus and soil layer depth; The data processing module performs a dynamic load test on the pipe pile to obtain the dynamic response data of the pipe pile, wherein the dynamic response characteristics are the natural frequency of the pipe pile and the damping ratio of the entire vibration system, and performs a correlation analysis on the natural frequency and the damping ratio to generate a dynamic response index; The index generation module generates a first impact index after dimensionally processing the collected pipe pile material properties and geometric properties; and generates a second impact index after dimensionally processing the collected soil parameters; The vertical dynamic stiffness determination module combines the first influence index, the second influence index and the dynamic response index to determine the vertical dynamic stiffness of the pipe pile.

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