A test method and system for friction characteristics of static drilled root piles and different contact surfaces

Abstract

The present invention relates to the technical field of material friction characteristic test, specifically to a test method and system for the friction characteristics of static drilled rooted piles and different contact surfaces. The present invention first divides a plurality of soil layer units according to the spatial distribution characteristics of the soil layer in the pile hole, and obtains the physical characteristic vector of each soil layer unit; then prepares pile material specimens and different types of soil layer specimens, and performs a ring shear test under standard prestress, temperature and moisture content conditions to obtain a first cohesion and a first friction angle; then calculates a correction coefficient according to the physical characteristic vector of the soil layer unit to obtain a second cohesion and a second friction angle, establishes a finite element mesh model and defines the mechanical behavior of the pile-soil contact surface according to the second cohesion and the second friction angle, and performs a simulation test to obtain the friction characteristic vector of the static drilled rooted pile and each soil layer contact surface; finally, an optimization algorithm is used to adjust the parameter set; the present invention can improve the reliability and accuracy of the friction characteristic test of the static drilled rooted pile and different contact surfaces.

Description

Technical Field

[0001] The invention relates to the technical field of material friction property testing, and in particular to a testing method and system for friction properties of a static drill rooted pile and different contact surfaces. Background Art

[0002] With the rapid development of urban construction, pile foundations are increasingly used in foundation engineering. As an important form of pile foundation, static drilled root piles are widely used in urban construction due to their advantages such as low construction noise, low vibration and little impact on the surrounding environment. The bearing capacity of static drilled root piles mainly depends on the friction between the pile side and the soil. Therefore, accurately obtaining the friction characteristics of the contact surface between static drilled root piles and different soil layers is of great significance for engineering design and construction.

[0003] At present, the test methods for the friction characteristics between static drilled root piles and different contact surfaces mainly include laboratory tests and on-site in-situ tests. However, laboratory tests often fail to fully consider the influence of soil depth and various environmental factors on friction characteristics, and fail to accurately restore the actual state of the soil layer, resulting in certain deviations in the test results; and on-site in-situ tests not only fail to fully reflect the spatial distribution characteristics of the soil layer, but also fail to accurately determine the friction characteristics of the static drilled root piles and the contact surfaces of different soil layers, and are costly. Therefore, the existing test methods are still insufficient in terms of accuracy and reliability.

[0004] Therefore, a test method and system for the friction characteristics of static drilled rooted piles and different contact surfaces are proposed. Summary of the invention

[0005] The purpose of the present invention is to provide a test method and system for the friction characteristics of a static drilled rooted pile with different contact surfaces. First, a plurality of soil layer units are divided according to the spatial distribution characteristics of the soil layer in the pile hole, and the physical characteristic vector of each soil layer unit is obtained; then, pile material specimens and different types of soil layer specimens are prepared, and a ring shear test is carried out under standard prestress, temperature and moisture content conditions to obtain a first cohesion and a first friction angle; then, a correction coefficient is calculated according to the physical characteristic vector of the soil layer unit to obtain a second cohesion and a second friction angle, a finite element mesh model is established, and the mechanical behavior of the pile-soil contact surface is defined according to the second cohesion and the second friction angle, and a simulation test is carried out to obtain the friction characteristic vector of the static drilled rooted pile with each soil layer contact surface; finally, an optimization algorithm is used to adjust the parameter set.

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

[0007] A test method for friction characteristics of static drilled root piles and different contact surfaces, comprising:

[0008] The spatial distribution characteristics of the soil layer in the pile hole are obtained according to the drilling report of the static drill root pile, and the soil layer in the pile hole is divided into Soil layer units are obtained to obtain a soil layer unit set;

[0009] Conducting on-site survey and testing on the soil layer units to obtain a physical property vector of each soil layer unit;

[0010] Prepare pile material specimens of static drilled rooted piles, obtain different types of soil layer specimens in the soil layer unit set, set standard vertical prestress, standard temperature and standard moisture content, perform ring shear tests on the soil layer specimens and the pile material specimens, and obtain the first cohesion and first friction angle of the contact surface between the static drilled rooted piles and different types of soil layers;

[0011] Calculating a correction coefficient according to the physical property vector of the soil layer unit, and calculating a second cohesion and a second friction angle of the contact surface between the static drilled root pile and each soil layer unit according to the correction coefficient, the first cohesion and the first friction angle; the correction coefficient includes a depth correction coefficient, a temperature correction coefficient and a moisture content correction coefficient;

[0012] According to the physical characteristic vector, the second cohesion and the second friction angle, a finite element mesh model is established and the mechanical behavior of the contact surface between the static drilled root pile and each of the soil layer units is defined;

[0013] Setting boundary conditions, performing simulation tests through the finite element mesh model, and obtaining friction characteristic vectors of the contact surface between the static drilled root pile and each of the soil layer units;

[0014] According to the measured data and the simulation test results of the finite element mesh model, the parameter set is adjusted using an optimization algorithm.

[0015] Preferably, the calculation formulas for the second cohesion and the second friction angle are:

[0016] ;

[0017] in, and Respectively represent the second cohesion and the second friction angle of the contact surface of each of the soil layer units; Indicates The first cohesion of the contact surface of the same type of soil layers of the soil layer units; Indicates The first friction angle of the contact surface of the same type of soil layers of the soil layer units; , and Respectively represent The depth correction coefficient, the temperature correction coefficient and the moisture content correction coefficient of each soil layer unit.

[0018] Preferably, the bulk density, thickness, temperature and moisture content of the soil layer unit are extracted according to the physical property vector, and the depth correction coefficient, the temperature correction coefficient and the moisture content correction coefficient are calculated. The calculation formula is:

[0019] ;

[0020] in, From the surface to the The number of soil layer units between the soil layer units; and Respectively In the soil unit The bulk density and thickness of each of the soil units; , and represent the standard vertical prestress, the standard temperature and the standard moisture content respectively; , and They represent stress index, temperature influence coefficient and moisture content influence coefficient respectively; and Respectively represent The temperature and moisture content of each soil unit.

[0021] Preferably, establishing the finite element mesh model and defining the mechanical behavior of the contact surface between the static drilled root pile and each of the soil layer units according to the physical property vector, the second cohesion and the second friction angle includes:

[0022] According to the physical characteristic vector, a pile geometry model, a soil geometry model and a The contact surface model of each soil layer unit;

[0023] Will The soil layer unit contact surface model is combined to obtain a pile-soil contact surface model, and the pile body geometric model, the soil body geometric model and the pile-soil contact surface model are meshed to generate a finite element mesh model;

[0024] The normal contact stiffness of the soil layer unit is extracted according to the physical property vector, and the normal contact behavior is defined as:

[0025] ;

[0026] in, Indicates Normal stress on the contact surface of each of the soil layer units; Indicates The normal contact stiffness of each of the soil layer elements; Indicates Normal permeability of the contact surface of each soil layer unit; Indicates The area of ​​the contact surface of each of the soil layer units;

[0027] The tangential contact stiffness of the soil layer unit is extracted according to the physical property vector, and the tangential contact behavior is defined in combination with the second cohesion and the second friction angle:

[0028] ;

[0029] in, Indicates The tangential stress of the contact surface of each of the soil layer units; Indicates The tangential contact stiffness of the soil layer contact surface; Indicates Tangential displacement of the contact surface of each soil layer; and Respectively represent The second cohesion and the second friction angle of the contact surface of each of the soil layer units.

[0030] Preferably, according to the measured data and the simulation test results, adjusting the parameter set by using an optimization algorithm includes:

[0031] S1. Perform a loading test on static drilled root piles to obtain measured data, and construct a multi-objective fitness function based on the measured data;

[0032] S2. Divide the initial population according to the parameter set and construct a parameter adaptive boundary; the parameter set includes a stress index, a temperature influence coefficient and a moisture content influence coefficient; the parameter adaptive boundary is expressed as:

[0033] ;

[0034] in, Indicates that the parameters in the parameter set are in The value in the iteration; Indicates the initial parameter value; represents the initial parameter shrinkage; Indicates the preset maximum number of iterations The coefficient of

[0035] S3. updating each of the initial populations using a co-evolutionary algorithm according to the parameter adaptive boundary, calculating the multi-objective fitness function values ​​of the individuals in the updated initial population, obtaining a new generation population and a Pareto optimal solution set; and using the new generation population as the initial population in the next iteration;

[0036] S4. Repeat the iteration step S3, stop the iteration when the number of iterations is greater than the preset maximum number of iterations, and adjust the parameter set according to the latest Pareto optimal solution set.

[0037] A test system for friction characteristics of static drilled root piles and different contact surfaces, comprising:

[0038] The soil layer division module obtains the spatial distribution characteristics of the pile hole soil layer according to the drilling report of the static drill root pile project site; divides the pile hole soil layer into Soil layer units are obtained to obtain a soil layer unit set;

[0039] The data acquisition module conducts on-site survey and testing on the soil layer unit to obtain the physical property vector of each soil layer unit; prepares pile material specimens of static drilled rooted piles, obtains different types of soil layer specimens in the soil layer unit set, sets standard vertical prestress, standard temperature and standard moisture content, conducts ring shear tests on the soil layer specimens and the pile material specimens, and obtains the first cohesion and first friction angle of the contact surface between the static drilled rooted piles and different types of soil layers;

[0040] A data correction module calculates a correction coefficient according to the physical property vector of the soil layer unit; calculates a second cohesion and a second friction angle of the contact surface between the static drilled root pile and each soil layer unit according to the correction coefficient, the first cohesion and the first friction angle; the correction coefficient includes a depth correction coefficient, a temperature correction coefficient and a moisture content correction coefficient;

[0041] A simulation test module, which establishes a finite element mesh model and defines the mechanical behavior of the contact surface between the static drilled rooted pile and each of the soil layer units according to the physical characteristic vector, the second cohesion and the second friction angle; sets boundary conditions, performs a simulation test through the finite element mesh model, and obtains the friction characteristic vector of the contact surface between the static drilled rooted pile and each of the soil layer units;

[0042] The parameter optimization module uses an optimization algorithm to adjust the parameter set according to the measured data and the simulation test results of the finite element mesh model.

[0043] Preferably, the calculation formulas for the second cohesion and the second friction angle are:

[0044] ;

[0045] in, and Respectively represent the second cohesion and the second friction angle of the contact surface of each of the soil layer units; Indicates The first cohesion of the contact surface of the same type of soil layers of the soil layer units; Indicates The first friction angle of the contact surface of the same type of soil layers of the soil layer units; , and Respectively represent The depth correction coefficient, the temperature correction coefficient and the moisture content correction coefficient of each soil layer unit.

[0046] Preferably, the bulk density, thickness, temperature and moisture content of the soil layer unit are extracted according to the physical property vector, and the depth correction coefficient, the temperature correction coefficient and the moisture content correction coefficient are calculated. The calculation formula is:

[0047] ;

[0048] in, From the surface to the The number of soil layer units between the soil layer units; and Respectively In the soil unit The bulk density and thickness of each of the soil units; , and represent the standard vertical prestress, the standard temperature and the standard moisture content respectively; , and They represent stress index, temperature influence coefficient and moisture content influence coefficient respectively; and Respectively represent The temperature and moisture content of each soil unit.

[0049] Preferably, establishing the finite element mesh model and defining the mechanical behavior of the contact surface between the static drilled root pile and each of the soil layer units according to the physical property vector, the second cohesion and the second friction angle includes:

[0050] According to the physical characteristic vector, a pile geometry model, a soil geometry model and a The contact surface model of each soil layer unit;

[0051] Will The soil layer unit contact surface model is combined to obtain a pile-soil contact surface model, and the pile body geometric model, the soil body geometric model and the pile-soil contact surface model are meshed to generate a finite element mesh model;

[0052] Extracting the normal contact stiffness of the soil layer unit according to the physical characteristic vector and defining the normal contact behavior;

[0053] The tangential contact stiffness of the soil layer unit is extracted according to the physical property vector, and the tangential contact behavior is defined in combination with the second cohesion and the second friction angle.

[0054] Preferably, according to the measured data and the simulation test results, adjusting the parameter set by using an optimization algorithm includes:

[0055] S1. Perform a loading test on static drilled root piles to obtain measured data, and construct a multi-objective fitness function based on the measured data;

[0056] S2. Dividing the initial population according to the parameter set and constructing a parameter adaptive boundary; the parameter set includes a stress index, a temperature influence coefficient, and a moisture content influence coefficient;

[0057] S3. updating each of the initial populations using a co-evolutionary algorithm according to the parameter adaptive boundary, calculating the multi-objective fitness function values ​​of the individuals in the updated initial population, obtaining a new generation population and a Pareto optimal solution set; and using the new generation population as the initial population in the next iteration;

[0058] S4. Repeat the iteration step S3, stop the iteration when the number of iterations is greater than the preset maximum number of iterations, and adjust the parameter set according to the latest Pareto optimal solution set.

[0059] Compared with the prior art, the present invention has the following beneficial effects:

[0060] 1. The present invention divides the pile hole into multiple soil layer units, and uses a correction coefficient to correct the cohesion and friction angle of each soil layer unit. The calculation of the correction coefficient takes into account the influence of the bulk density, thickness, temperature and moisture content of the soil layer on the friction characteristics; the method of correcting each soil layer unit can more accurately reflect the real friction characteristics between the static drill rooted pile and each soil layer, reduce the error of the ring shear test under fixed environmental conditions, provide more accurate parameter input for subsequent simulation tests, and improve the reliability and accuracy of the friction characteristics test between the static drill rooted pile and different contact surfaces.

[0061] 2. The present invention defines the mechanical behavior of the contact surface between the static drilled rooted pile and each soil layer unit in the finite element grid model according to the physical properties of different soil layer units and the corrected cohesion and friction angle; describes the normal contact behavior by the normal contact stiffness and permeability of each soil layer unit, and defines the tangential contact behavior in combination with the corrected cohesion and friction angle; takes into account the differences between different soil layer units, more comprehensively describes the interaction between the static drilled rooted pile and the soil layer units, realizes the accurate simulation of the pile-soil contact mechanical behavior, provides a theoretical basis for obtaining accurate friction characteristics, and improves the reliability and accuracy of the friction characteristics test of the static drilled rooted pile and different contact surfaces.

[0062] 3. The present invention provides a parameter optimization method based on a multi-objective fitness function. The optimization process adopts a co-evolutionary algorithm to adjust the parameter set by iteratively updating the initial population and the Pareto optimal solution set. A parameter adaptive boundary is introduced in the optimization method to ensure the convergence of the optimization process and the reliability of the results. The optimization method can automatically adjust key parameters to make the simulation results of the finite element mesh model more consistent with the actual situation. By continuously optimizing the parameter set, the reliability and accuracy of the friction characteristics test between static drilled root piles and different contact surfaces can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 It is a schematic flow chart of a test method for friction characteristics of a static drilled root pile with different contact surfaces according to the present invention;

[0064] Figure 2 It is a schematic diagram of soil layer unit division of the present invention;

[0065] Figure 3 The present invention is a schematic diagram of the structure of a test system for friction characteristics between a statically drilled root pile and different contact surfaces. DETAILED DESCRIPTION

[0066] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0067] Embodiment 1

[0068] The stratum conditions at a certain engineering site are complex, and the surface layer is a thick soft soil layer, which has high requirements on the bearing performance and settlement control of the pile foundation. In order to determine the design parameters of the pile foundation under complex stratum conditions and ensure the quality of the project and the safety of the surrounding environment, a test method for the friction characteristics of static drilled root piles with different contact surfaces of the present invention is applied, such as Figure 1 As shown, including:

[0069] The spatial distribution characteristics of the soil layer in the pile hole are obtained according to the drilling report of the static drill root pile, and the soil layer in the pile hole is divided into Soil layer units, such as Figure 2 As shown, the soil layer unit set is obtained: {soil layer unit 1, soil layer unit 2, ..., soil layer unit , soil layer unit };

[0070] Conducting on-site survey and testing on the soil layer units to obtain a physical property vector of each soil layer unit;

[0071] Prepare pile material specimens of static drilled rooted piles, obtain different types of soil layer specimens in the soil layer unit set, set standard vertical prestress, standard temperature and standard moisture content, perform ring shear tests on the soil layer specimens and the pile material specimens, and obtain the first cohesion and first friction angle of the contact surface between the static drilled rooted piles and different types of soil layers;

[0072] Calculating a correction coefficient according to the physical property vector of the soil layer unit, and calculating a second cohesion and a second friction angle of the contact surface between the static drilled root pile and each soil layer unit according to the correction coefficient, the first cohesion and the first friction angle; the correction coefficient includes a depth correction coefficient, a temperature correction coefficient and a moisture content correction coefficient;

[0073] According to the physical characteristic vector, the second cohesion and the second friction angle, a finite element mesh model is established and the mechanical behavior of the contact surface between the static drilled root pile and each of the soil layer units is defined;

[0074] Setting boundary conditions, performing simulation tests through the finite element mesh model, and obtaining friction characteristic vectors of the contact surface between the static drilled root pile and each of the soil layer units;

[0075] According to the measured data and simulation test results, the optimization algorithm is used to adjust the parameter set.

[0076] In the embodiment of the present application, the soil layer within the pile length range is divided into 7 soil layer units, and some physical properties of each soil layer unit are shown in Table 1.

[0077] Table 1 Physical properties of soil layer units

[0078]

[0079] In the embodiment of the present application, ring shear tests were carried out on pile specimens of five soil layer types, namely fill, silty clay, silty clay, fine sand, and fine sand mixed with clay. The test was repeated three times for each soil layer type, and the average value was taken as the test result. The results are shown in Table 2.

[0080] Table 2 Ring shear test results

[0081]

[0082] Furthermore, the calculation formulas for the second cohesion and the second friction angle are:

[0083] ;

[0084] in, and Respectively represent the second cohesion and the second friction angle of the contact surface of each of the soil layer units; Indicates The first cohesion of the contact surface of the same type of soil layers of the soil layer units; Indicates The first friction angle of the contact surface of the same type of soil layers of the soil layer units; , and Respectively represent The depth correction coefficient, the temperature correction coefficient and the moisture content correction coefficient of each soil layer unit.

[0085] The depth correction coefficient, temperature correction coefficient and moisture content correction coefficient are introduced into the calculation of the second cohesion and the second friction angle, which realizes the accurate correction of the initial parameters obtained from the ring shear test and takes into account the coupling effect of multiple influencing factors, making the cohesion and friction angle more in line with the actual situation.

[0086] Furthermore, the bulk density, thickness, temperature and moisture content of the soil layer unit are extracted according to the physical property vector, and the depth correction coefficient, the temperature correction coefficient and the moisture content correction coefficient are calculated. The calculation formula is:

[0087] ;

[0088] in, From the surface to the The number of soil layer units between the soil layer units; and Respectively In the soil unit The bulk density and thickness of each of the soil units; , and represent the standard vertical prestress, the standard temperature and the standard moisture content respectively; , and They represent stress index, temperature influence coefficient and moisture content influence coefficient respectively; and Respectively represent The temperature and moisture content of each soil unit.

[0089] The physical properties of the soil layer, such as bulk density and thickness, as well as environmental factors such as temperature and moisture content, are quantified into specific correction coefficients. The quantitative correction method makes the test repeatable, improves the operability of the correction process, and reduces the workload of the friction characteristics test between static drilled root piles and different contact surfaces.

[0090] The second cohesion and second friction angle of each soil layer unit calculated by the correction coefficient in the embodiment of the present application are shown in Table 3.

[0091] Table 3 Second cohesion and second friction angle of soil layer elements

[0092]

[0093] Further, according to the physical property vector, the second cohesion and the second friction angle, establishing the finite element mesh model and defining the mechanical behavior of the contact surface between the static drilled root pile and each of the soil layer units includes:

[0094] According to the physical characteristic vector, a pile geometry model, a soil geometry model and a The contact surface model of each soil layer unit;

[0095] Will The soil layer unit contact surface model is combined to obtain a pile-soil contact surface model, and the pile body geometric model, the soil body geometric model and the pile-soil contact surface model are meshed to generate a finite element mesh model;

[0096] The normal contact stiffness of the soil layer unit is extracted according to the physical property vector, and the normal contact behavior is defined as:

[0097] ;

[0098] in, Indicates Normal stress on the contact surface of each of the soil layer units; Indicates The normal contact stiffness of each of the soil layer elements; Indicates Normal permeability of the contact surface of each soil layer unit; Indicates The area of ​​the contact surface of each of the soil layer units;

[0099] The tangential contact stiffness of the soil layer unit is extracted according to the physical property vector, and the tangential contact behavior is defined in combination with the second cohesion and the second friction angle:

[0100] ;

[0101] in, Indicates The tangential stress of the contact surface of each of the soil layer units; Indicates The tangential contact stiffness of the soil layer contact surface; Indicates Tangential displacement of the contact surface of each soil layer; and Respectively represent The second cohesion and the second friction angle of the contact surface of each of the soil layer units.

[0102] By establishing a complete mechanical model including normal contact behavior and tangential contact behavior, and combining the physical property vector, second cohesion and second friction angle, an accurate description of the mechanical behavior of the pile-soil contact surface is achieved, which can more comprehensively reflect the interaction mechanism between static drilled rooted piles and soil layers.

[0103] Further, according to the measured data and the simulation test results, the parameter set is adjusted by using an optimization algorithm, including:

[0104] S1. Perform a loading test on static drilled root piles to obtain measured data, and construct a multi-objective fitness function based on the measured data;

[0105] S2. Divide the initial population according to the parameter set and construct a parameter adaptive boundary; the parameter set includes a stress index, a temperature influence coefficient and a moisture content influence coefficient; the parameter adaptive boundary is expressed as:

[0106] ;

[0107] in, Indicates that the parameters in the parameter set are in The value in the iteration; Indicates the initial parameter value; represents the initial parameter shrinkage; Indicates the preset maximum number of iterations The coefficient of

[0108] S3. updating each of the initial populations using a co-evolutionary algorithm according to the parameter adaptive boundary, calculating the multi-objective fitness function values ​​of the individuals in the updated initial population, obtaining a new generation population and a Pareto optimal solution set; and using the new generation population as the initial population in the next iteration;

[0109] S4. Repeat the iteration step S3, stop the iteration when the number of iterations is greater than the preset maximum number of iterations, and adjust the parameter set according to the latest Pareto optimal solution set.

[0110] By introducing a multi-objective fitness function and parameter adaptive boundaries, and using a collaborative evolutionary algorithm for parameter optimization, automatic adjustment of key parameters such as stress exponent, temperature influence coefficient and moisture content influence coefficient is achieved; the optimization method has strong adaptability and convergence, which can make the simulation test results more consistent with the actual loading test results, thereby improving the accuracy of the test method.

[0111] The present invention provides a test method for the friction characteristics of a static drilled rooted pile and different contact surfaces, which ensures that the method can accurately reflect the pile-soil contact characteristics under complex geological conditions by dividing a plurality of soil layer units; the physical characteristic vectors of each soil layer unit are obtained through on-site survey and testing, and combined with a ring shear test, the first cohesion and the first friction angle of the contact surface between the static drilled rooted pile and different types of soil bodies are obtained, thereby providing accurate mechanical data for subsequent calculations; the present invention introduces a depth correction coefficient, a temperature correction coefficient and a moisture content correction coefficient, which can truly reflect the pile-soil contact behavior under conditions of different depths, temperatures and moisture contents, and improves the accuracy and adaptability of the friction characteristic test; the present invention defines the mechanical behavior of the contact surface by establishing a finite element mesh model, and can comprehensively and accurately simulate the friction characteristic test; the present invention adjusts the parameter set through an optimization algorithm, ensures the consistency between the simulation test results and the measured data, and improves the accuracy and stability of the friction characteristic test; the present invention overcomes the problem that the traditional test method ignores the influence of soil layer differences and environmental factors, and improves the accuracy and reliability of the friction characteristic test between the static drilled rooted pile and different contact surfaces.

[0112] Embodiment 2

[0113] The present invention also provides a test system for the friction characteristics of static drilled rooted piles and different contact surfaces, and applies a test method for the friction characteristics of static drilled rooted piles and different contact surfaces, such as Figure 3 As shown, including:

[0114] The soil layer division module obtains the spatial distribution characteristics of the pile hole soil layer according to the drilling report of the static drill root pile project site; divides the pile hole soil layer into Soil layer units are obtained to obtain a soil layer unit set;

[0115] The data acquisition module conducts on-site survey and testing on the soil layer unit to obtain the physical property vector of each soil layer unit; prepares pile material specimens of static drilled rooted piles, obtains different types of soil layer specimens in the soil layer unit set, sets standard vertical prestress, standard temperature and standard moisture content, conducts ring shear tests on the soil layer specimens and the pile material specimens, and obtains the first cohesion and first friction angle of the contact surface between the static drilled rooted piles and different types of soil layers;

[0116] A data correction module calculates a correction coefficient according to the physical property vector of the soil layer unit; calculates a second cohesion and a second friction angle of the contact surface between the static drilled root pile and each soil layer unit according to the correction coefficient, the first cohesion and the first friction angle; the correction coefficient includes a depth correction coefficient, a temperature correction coefficient and a moisture content correction coefficient;

[0117] A simulation test module, which establishes a finite element mesh model and defines the mechanical behavior of the contact surface between the static drilled rooted pile and each of the soil layer units according to the physical characteristic vector, the second cohesion and the second friction angle; sets boundary conditions, performs a simulation test through the finite element mesh model, and obtains the friction characteristic vector of the contact surface between the static drilled rooted pile and each of the soil layer units;

[0118] The parameter optimization module uses an optimization algorithm to adjust the parameter set according to the measured data and the simulation test results of the finite element mesh model.

[0119] Furthermore, the calculation formulas for the second cohesion and the second friction angle are:

[0120] ;

[0121] in, and Respectively represent the second cohesion and the second friction angle of the contact surface of each of the soil layer units; Indicates The first cohesion of the contact surface of the same type of soil layers of the soil layer units; Indicates The first friction angle of the contact surface of the same type of soil layers of the soil layer units; , and Respectively represent The depth correction coefficient, the temperature correction coefficient and the moisture content correction coefficient of each soil layer unit.

[0122] Furthermore, the bulk density, thickness, temperature and moisture content of the soil layer unit are extracted according to the physical property vector, and the depth correction coefficient, the temperature correction coefficient and the moisture content correction coefficient are calculated. The calculation formula is:

[0123] ;

[0124] in, From the surface to the The number of soil layer units between the soil layer units; and Respectively In the soil unit The bulk density and thickness of each of the soil units; , and represent the standard vertical prestress, the standard temperature and the standard moisture content respectively; , and They represent stress index, temperature influence coefficient and moisture content influence coefficient respectively; and Respectively represent The temperature and moisture content of each soil unit.

[0125] Further, according to the physical property vector, the second cohesion and the second friction angle, establishing the finite element mesh model and defining the mechanical behavior of the contact surface between the static drilled root pile and each of the soil layer units includes:

[0126] According to the physical characteristic vector, a pile geometry model, a soil geometry model and a The contact surface model of each soil layer unit;

[0127] Will The soil layer unit contact surface model is combined to obtain a pile-soil contact surface model, and the pile body geometric model, the soil body geometric model and the pile-soil contact surface model are meshed to generate a finite element mesh model;

[0128] Extracting the normal contact stiffness of the soil layer unit according to the physical characteristic vector and defining the normal contact behavior;

[0129] The tangential contact stiffness of the soil layer unit is extracted according to the physical property vector, and the tangential contact behavior is defined in combination with the second cohesion and the second friction angle.

[0130] Further, according to the measured data and the simulation test results, the parameter set is adjusted by using an optimization algorithm, including:

[0131] S1. Perform a loading test on static drilled root piles to obtain measured data, and construct a multi-objective fitness function based on the measured data;

[0132] S2. Dividing the initial population according to the parameter set and constructing a parameter adaptive boundary; the parameter set includes a stress index, a temperature influence coefficient, and a moisture content influence coefficient;

[0133] S3. updating each of the initial populations using a co-evolutionary algorithm according to the parameter adaptive boundary, calculating the multi-objective fitness function values ​​of the individuals in the updated initial population, obtaining a new generation population and a Pareto optimal solution set; and using the new generation population as the initial population in the next iteration;

[0134] S4. Repeat the iteration step S3, stop the iteration when the number of iterations is greater than the preset maximum number of iterations, and adjust the parameter set according to the latest Pareto optimal solution set.

[0135] The embodiment of the present application uses the optimized parameters to carry out simulation tests, and the comparison between the simulation test results and the measured data of the pile top displacement (mm) is shown in Table 4. Under different levels of load, the relative error between the simulation results and the measured data for the pile top displacement (mm) is less than 4%.

[0136] Table 4 Comparison of simulation test results and measured data

[0137]

[0138] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A test method for the friction characteristics of static drilled root piles and different contact surfaces, characterized in that: include: The spatial distribution characteristics of the soil layer in the pile hole are obtained according to the drilling report of the static drill root pile, and the soil layer in the pile hole is divided into Soil layer units are obtained to obtain a soil layer unit set; Conducting on-site survey and testing on the soil layer units to obtain a physical property vector of each soil layer unit; Prepare pile material specimens of static drilled rooted piles, obtain different types of soil layer specimens in the soil layer unit set, set standard vertical prestress, standard temperature and standard moisture content, perform ring shear tests on the soil layer specimens and the pile material specimens, and obtain the first cohesion and first friction angle of the contact surface between the static drilled rooted piles and different types of soil layers; Calculating a correction coefficient according to the physical property vector of the soil layer unit, and calculating a second cohesion and a second friction angle of the contact surface between the static drilled root pile and each soil layer unit according to the correction coefficient, the first cohesion and the first friction angle; the correction coefficient includes a depth correction coefficient, a temperature correction coefficient and a moisture content correction coefficient; According to the physical property vector, the second cohesion and the second friction angle, a finite element mesh model is established and the mechanical behavior of the contact surface between the static drilled root pile and each of the soil layer units is defined, including: The normal contact stiffness of the soil layer unit is extracted according to the physical property vector, and the normal contact behavior is defined as: ； in, , , and Respectively represent The normal stress, normal contact stiffness, normal permeability and area of ​​the contact surface of each soil layer unit; The tangential contact stiffness of the soil layer unit is extracted according to the physical property vector, and the tangential contact behavior is defined in combination with the second cohesion and the second friction angle: ； in, , , , and Respectively represent The tangential stress, tangential contact stiffness, tangential displacement, second cohesion and second friction angle of the contact surface of each of the soil layer units; Setting boundary conditions, performing simulation tests through the finite element mesh model, and obtaining friction characteristic vectors of the contact surface between the static drilled root pile and each of the soil layer units; According to the measured data and the simulation test results of the finite element mesh model, the parameter set is adjusted using an optimization algorithm.

2. The test method for the friction characteristics of static drilled root piles and different contact surfaces according to claim 1 is characterized in that: The calculation formulas of the second cohesion and the second friction angle are: ； in, and Respectively represent the second cohesion and the second friction angle of the contact surface of each of the soil layer units; Indicates The first cohesion of the contact surface of the same type of soil layers of the soil layer units; Indicates The first friction angle of the contact surface of the same type of soil layers of the soil layer units; , and Respectively represent The depth correction coefficient, the temperature correction coefficient and the moisture content correction coefficient of each soil layer unit.

3. The test method for the friction characteristics of static drilled root piles and different contact surfaces according to claim 1 is characterized in that: The bulk density, thickness, temperature and moisture content of the soil layer unit are extracted according to the physical characteristic vector, and the depth correction coefficient, the temperature correction coefficient and the moisture content correction coefficient are calculated. The calculation formula is: ； in, From the surface to the The number of soil layer units between the soil layer units; and Respectively In the soil unit The bulk density and thickness of each of the soil units; , and represent the standard vertical prestress, the standard temperature and the standard moisture content respectively; , and They represent stress index, temperature influence coefficient and moisture content influence coefficient respectively; and Respectively represent The temperature and moisture content of each soil unit.

4. The test method for the friction characteristics of static drilled root piles and different contact surfaces according to claim 1 is characterized in that: Establishing the finite element mesh model includes: According to the physical characteristic vector, a pile geometry model, a soil geometry model and a The contact surface model of each soil layer unit; Will The soil layer unit contact surface models are combined to obtain a pile-soil contact surface model, and the pile body geometric model, the soil body geometric model and the pile-soil contact surface model are meshed to generate a finite element mesh model.

5. The test method for the friction characteristics of static drilled root piles and different contact surfaces according to claim 1 is characterized in that: According to the measured data and simulation test results, the optimization algorithm is used to adjust the parameter set including: S1. Perform a loading test on static drilled root piles to obtain measured data, and construct a multi-objective fitness function based on the measured data; S2. Divide the initial population according to the parameter set and construct a parameter adaptive boundary; the parameter set includes a stress index, a temperature influence coefficient and a moisture content influence coefficient; the parameter adaptive boundary is expressed as: ； in, Indicates that the parameters in the parameter set are in The value in the iteration; Indicates the initial parameter value; represents the initial parameter shrinkage; Indicates the preset maximum number of iterations The coefficient of S3. updating each of the initial populations using a co-evolutionary algorithm according to the parameter adaptive boundary, calculating the multi-objective fitness function values ​​of the individuals in the updated initial population, obtaining a new generation population and a Pareto optimal solution set; and using the new generation population as the initial population in the next iteration; S4. Repeat the iteration step S3, stop the iteration when the number of iterations is greater than the preset maximum number of iterations, and adjust the parameter set according to the latest Pareto optimal solution set.

6. A test system for the friction characteristics of static drilled root piles and different contact surfaces, characterized in that: include: The soil layer division module obtains the spatial distribution characteristics of the soil layer in the pile hole according to the drilling report of the static drill root pile project site; According to the spatial distribution characteristics, the pile hole soil layer is divided into Soil layer units are obtained to obtain a soil layer unit set; The data acquisition module conducts on-site survey and testing on the soil layer unit to obtain the physical property vector of each soil layer unit; prepares pile material specimens of static drilled rooted piles, obtains different types of soil layer specimens in the soil layer unit set, sets standard vertical prestress, standard temperature and standard moisture content, conducts ring shear tests on the soil layer specimens and the pile material specimens, and obtains the first cohesion and first friction angle of the contact surface between the static drilled rooted piles and different types of soil layers; A data correction module calculates a correction coefficient according to the physical property vector of the soil layer unit; calculates a second cohesion and a second friction angle of the contact surface between the static drilled root pile and each soil layer unit according to the correction coefficient, the first cohesion and the first friction angle; the correction coefficient includes a depth correction coefficient, a temperature correction coefficient and a moisture content correction coefficient; A simulation test module, which establishes a finite element mesh model and defines the mechanical behavior of the contact surface between the static drilled rooted pile and each of the soil layer units according to the physical characteristic vector, the second cohesion and the second friction angle; sets boundary conditions, performs a simulation test through the finite element mesh model, and obtains the friction characteristic vector of the contact surface between the static drilled rooted pile and each of the soil layer units; A parameter optimization module, which uses an optimization algorithm to adjust a parameter set according to measured data and simulation test results of the finite element mesh model; The mechanical behavior of the contact surface between the static drilled pile and each soil layer unit is defined as follows: The normal contact stiffness of the soil layer unit is extracted according to the physical property vector, and the normal contact behavior is defined as: ； in, , , and Respectively represent The normal stress, normal contact stiffness, normal permeability and area of ​​the contact surface of each soil layer unit; The tangential contact stiffness of the soil layer unit is extracted according to the physical property vector, and the tangential contact behavior is defined in combination with the second cohesion and the second friction angle: ； in, , , , and Respectively represent The tangential stress, tangential contact stiffness, tangential displacement, second cohesion and second friction angle of the contact surface of the soil layer unit are calculated.

7. A test system for friction characteristics between static drilled root piles and different contact surfaces according to claim 6, characterized in that: The calculation formulas of the second cohesion and the second friction angle are: ； in, and Respectively represent the second cohesion and the second friction angle of the contact surface of each of the soil layer units; Indicates The first cohesion of the contact surface of the same type of soil layers of the soil layer units; Indicates The first friction angle of the contact surface of the same type of soil layers of the soil layer units; , and Respectively represent The depth correction coefficient, the temperature correction coefficient and the moisture content correction coefficient of each soil layer unit.

8. The test system for friction characteristics between static drilled root piles and different contact surfaces according to claim 6, characterized in that: The bulk density, thickness, temperature and moisture content of the soil layer unit are extracted according to the physical characteristic vector, and the depth correction coefficient, the temperature correction coefficient and the moisture content correction coefficient are calculated. The calculation formula is: ； in, From the surface to the The number of soil layer units between the soil layer units; and Respectively In the soil unit The bulk density and thickness of each of the soil units; , and represent the standard vertical prestress, the standard temperature and the standard moisture content respectively; , and They represent stress index, temperature influence coefficient and moisture content influence coefficient respectively; and Respectively represent The temperature and moisture content of each soil unit.

9. A test system for friction characteristics between static drilled root piles and different contact surfaces according to claim 6, characterized in that: Establishing the finite element mesh model includes: According to the physical characteristic vector, a pile geometry model, a soil geometry model and a The contact surface model of each soil layer unit; Will The soil layer unit contact surface models are combined to obtain a pile-soil contact surface model, and the pile body geometric model, the soil body geometric model and the pile-soil contact surface model are meshed to generate a finite element mesh model.

10. A test system for friction characteristics between static drilled root piles and different contact surfaces according to claim 6, characterized in that: According to the measured data and simulation test results, the parameter set is adjusted by using an optimization algorithm including: S1. Perform a loading test on static drilled root piles to obtain measured data, and construct a multi-objective fitness function based on the measured data; S2. Dividing the initial population according to the parameter set and constructing a parameter adaptive boundary; the parameter set includes a stress index, a temperature influence coefficient, and a moisture content influence coefficient; S3. updating each of the initial populations using a co-evolutionary algorithm according to the parameter adaptive boundary, calculating the multi-objective fitness function values ​​of the individuals in the updated initial population, obtaining a new generation population and a Pareto optimal solution set; and using the new generation population as the initial population in the next iteration; S4. Repeat the iteration step S3, stop the iteration when the number of iterations is greater than the preset maximum number of iterations, and adjust the parameter set according to the latest Pareto optimal solution set.

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