Method and system for determining parameters of red clay pile foundation

Abstract

The invention discloses a red clay pile foundation parameter determination method and system, relates to the technical field of geotechnical engineering, and solves the problem that the pile end resistance value of a red clay pile foundation is inaccurate in an existing method. According to the embodiment of the invention, the CPTU continuous in-situ test parameters are dynamically associated with the red clay soil parameters, so that the mechanical properties of the pile end soil body are identified and partitioned, and the defects of sparse dependence and sample disturbance in the prior art are overcome. Meanwhile, differentiated calculation sub-models are established according to different plastic state partitions, so that the end resistance value is changed into a dynamic calculation value based on the real state of the soil body from a single empirical value, the accuracy and reliability of calculating the end resistance in the red clay which is the high-variability soil body are improved, the unreasonable pile length design caused by improper parameter values is effectively avoided, and the calculation accuracy is improved. Therefore, on the premise of ensuring the engineering safety, the engineering cost is optimized, and the construction risk is reduced.

Description

Technical Field

[0001] This invention relates to the field of geotechnical engineering technology, and in particular to a method and system for determining parameters of red clay pile foundations. Background Technology

[0002] When carrying out engineering construction in areas with red clay distribution, large-diameter piles, with their advantages of strong bearing capacity and good stability, are widely used in the foundation structures of major projects such as buildings and bridges. As the core parameter determining the vertical bearing capacity of large-diameter pile foundations, the accuracy of its value directly affects the safety, economy, and rationality of pile foundation design, making it a crucial and core aspect of the design process for large-diameter pile foundations in red clay regions.

[0003] Currently, the traditional method for determining the end resistance of large-diameter pile foundations in red clay regions in engineering mainly involves obtaining reference values ​​for end resistance from empirical tables in national or regional geotechnical engineering codes. These empirical tables are often based on limited geological conditions, pile types, and engineering case studies, and are insufficiently adaptable to red clay, a soil with unique genesis and complex mechanical properties. In particular, they fail to fully consider the significant differences in the plastic state of red clay, whose mechanical properties vary greatly under different plastic states, directly affecting the determination of end resistance. Using uniform empirical values ​​can easily lead to overly conservative designs, significantly increasing project costs, or to overly risky values, creating potential structural safety hazards.

[0004] Therefore, a method and system for determining the parameters of red clay pile foundations are needed. Summary of the Invention

[0005] To address the problem of inaccurate values ​​for the end resistance of red clay pile foundations in existing technologies, this invention provides a method and system for determining the parameters of red clay pile foundations, enabling more accurate determination of the end resistance. The specific technical solution is as follows: In a first aspect, embodiments of this application provide a method for determining parameters of red clay pile foundations, including: A cone penetration test (CPTU) was conducted in the pile location area to obtain the CPTU curve. Uncirculated soil samples were collected at key depths in the pile location area, and soil parameters were measured. These key depths included a first key depth determined based on the cone tip resistance and pore water pressure in the CPTU curve, and a second key depth where the pre-defined pile tip bearing layer was located. Based on these soil parameters, a three-dimensional zoning map of the plasticity state of the red clay in the pile location area was generated. Measured values ​​of pile tip resistance within different plasticity state zoning zones were obtained. Based on the measured values ​​of pile tip resistance at the same depth and soil parameters, sub-models for calculating pile tip resistance applicable to different plasticity state zoning zones were established, forming a sub-model library. Based on the designed pile tip elevation of the target pile, the plasticity state and soil parameters of the soil layer within the corresponding pile tip influence depth range were extracted from the three-dimensional zoning map, and the corresponding sub-models were used to calculate the characteristic value of the pile tip resistance after the target pile was deployed at the pile location.

[0006] Preferably, the CPTU curve includes curves showing the variation of cone tip resistance, sidewall friction, and pore water pressure with depth; the process of collecting undisturbed target soil samples at key depths in the pile location area and determining the soil parameters of the undisturbed target soil samples includes: determining a first key depth based on the characteristic points of the variation curve, and collecting undisturbed target soil samples at the first key depth and the second key depth; determining the natural water content, liquid limit, and plastic limit of the undisturbed target soil samples, and calculating the water content ratio of the undisturbed target soil samples; and pairing the water content ratio, natural water content, liquid limit, and plastic limit at the same depth to form the soil parameters.

[0007] Preferably, the process of generating a three-dimensional zoning map of the plastic state of red clay in the pile location area based on the soil parameters includes: calculating the normalized cone tip resistance and normalized friction ratio at each key depth based on the soil parameters; calculating the soil behavior type index based on the normalized cone tip resistance and normalized friction ratio to obtain a soil behavior type index profile; establishing a site-specific statistical relationship model between the soil behavior type index and the measured water content based on the soil parameters; inputting the continuous soil behavior type index profile into the statistical relationship model to invert and obtain an equivalent water content profile; converting the equivalent water content profile into a plastic state profile according to a preset mapping relationship between the equivalent water content and the plastic state; and generating the three-dimensional zoning map based on the plastic state profile and the soil parameters.

[0008] Preferably, the method involves acquiring measured values ​​of pile end resistance within different plasticity state zones, and establishing pile end resistance calculation sub-models applicable to different plasticity state zones based on measured values ​​of pile end resistance at the same depth and soil parameters, forming a calculation sub-model library. This includes: acquiring measured values ​​of pile end resistance within different plasticity state zones through deep plate load tests or pile static load tests; determining the spatial location and pile end elevation of each test point corresponding to the measured value of pile end resistance; identifying the main plasticity state category affecting the depth of the test point from the three-dimensional zoning map; and extracting the normalized cone tip resistance and equivalent water content at the same depth; grouping the test data according to the plasticity state category; performing multiple regression analysis on each group of test data, using the normalized cone tip resistance and the equivalent water content as independent variables and the measured value of pile end resistance as the dependent variable, to establish a pile end resistance calculation sub-model under the corresponding plasticity state category; and compiling all calculation sub-models for all plasticity state categories to form the calculation sub-model library.

[0009] Preferably, based on the design pile tip elevation of the target pile, the soil plasticity state and soil parameters within the corresponding pile tip influence depth range are extracted from the three-dimensional zoning map, and the corresponding calculation sub-model is called to calculate the pile tip resistance characteristic value after the target pile is deployed at the pile location. This includes: obtaining the design pile tip elevation and pile diameter of the target pile; determining the pile tip influence depth range based on the design elevation and pile diameter; extracting soil layer information within the pile tip influence depth range from the three-dimensional zoning map, including the plasticity state category, layer thickness, normalized cone tip resistance, and equivalent water content of each soil layer; for each soil layer, calling the corresponding calculation sub-model from the calculation sub-model library according to its plasticity state category, substituting the corresponding normalized cone tip resistance and equivalent water content, and calculating the unit end resistance contribution value of the soil layer; and calculating the pile tip resistance characteristic value based on the unit end resistance contribution value, layer thickness, and preset weighting coefficient of each soil layer.

[0010] Preferably, the value of the weighting coefficient is related to the plasticity state category of the soil layer, wherein the weighting coefficient of the stiff plastic soil layer is higher than that of the plastic soil layer, and the weighting coefficient of the plastic soil layer is higher than that of the soft plastic soil layer.

[0011] Preferably, after the corresponding calculation sub-model is invoked to calculate the characteristic value of the pile end resistance after the target pile is deployed at the pile location, the method further includes: calculating the characteristic value of the vertical bearing capacity of the single pile of the target pile based on the characteristic value of the pile end resistance.

[0012] Secondly, embodiments of this application provide a red clay pile foundation parameter determination system, applied to the method described in the first aspect, the system comprising: The CPTU module is used to perform static cone penetration test (CPTU) in the pile location area to obtain the CPTU curve; The measurement module is used to collect target undisturbed soil samples at key depths in the pile location area and measure the soil parameters of the target undisturbed soil samples; wherein, the key depths include a first key depth determined based on the cone tip resistance and pore water pressure in the CPTU curve, and a second key depth where the preset pile end bearing layer is located; The generation module is used to generate a three-dimensional partition map of the plastic state of red clay in the pile location area based on the soil parameters. The modeling module is used to obtain the measured values ​​of pile end resistance in different plastic state zones, and based on the measured values ​​of pile end resistance at the same depth and soil parameters, to establish pile end resistance calculation sub-models applicable to different plastic state zones, forming a calculation sub-model library; The calculation module is used to extract the soil plasticity state and soil parameters within the corresponding pile tip influence depth range from the three-dimensional partition map based on the design pile tip elevation of the target pile, and call the corresponding calculation sub-model to calculate the pile tip resistance characteristic value of the target pile after it is deployed at the pile position.

[0013] Thirdly, embodiments of this application provide a computing device, including: a memory for storing a program; and a processor for loading the program to execute the method as described in the first aspect.

[0014] Fourthly, embodiments of this application provide a computer-readable storage medium including a stored program, wherein, when the program is executed, it controls the device where the computer-readable storage medium is located to perform the method described in the first aspect.

[0015] Compared with existing technologies, the beneficial effects of this invention are as follows: By dynamically correlating CPTU continuous in-situ test parameters with red clay soil parameters, the mechanical properties of the pile tip soil are identified and zoned, overcoming the shortcomings of traditional methods that rely on sparse and disturbed samples. Simultaneously, differentiated calculation sub-models are established for different plastic state zones, transforming the end resistance value from a single empirical value to a dynamically calculated value based on the actual soil state. This improves the accuracy and reliability of end resistance calculation in highly variable soils like red clay, effectively avoiding unreasonable pile length design due to improper parameter values. Therefore, while ensuring project safety, this invention optimizes project costs and reduces construction risks. Attached Figure Description

[0016] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.

[0017] Figure 1A flowchart illustrating a method for determining parameters of red clay pile foundations provided in this application embodiment; Figure 2 A schematic diagram of a red clay pile foundation parameter determination system provided in this application embodiment; Figure 3 This is a schematic diagram of the structure of a computing device provided in an embodiment of this application. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0020] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0021] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0022] To address the problem of inaccurate values ​​for the end resistance of red clay pile foundations obtained by traditional methods, this invention provides a method and system for determining parameters of red clay pile foundations, which can yield more accurate values ​​for the end resistance of red clay pile foundations.

[0023] Please see Figure 1 , Figure 1 This application provides a flowchart illustrating a method for determining parameters of red clay pile foundations; as shown in the embodiments. Figure 1 As shown, the method includes: Step 101: Conduct a cone penetration test with pore pressure measurement (CPTU) in the pile location area to obtain the CPTU curve.

[0024] One or more testing devices can be deployed in the pile location area and centrally controlled and managed via on-site or remote servers or other computing equipment. Specifically, a pore pressure static cone penetrometer (CPTU) conforming to international standards can be used to deploy at least four CPTU test points at the center point of the target pile location and within a radius of 15-30 meters centered on the pile location, forming a small exploration network capable of controlling the spatial variation of the bearing stratum at the pile tip. The specific radius can be determined based on the geological complexity.

[0025] Specifically, this small exploration network is used to explore whether there is spatial variation in the plastic state of the bearing stratum at the pile tip within the pile location area, providing a basis for differentiating the values ​​of pile tip resistance at different pile locations.

[0026] Among them, the pile tip, also known as the pile tip, refers to the end structure that is in direct contact with the soil layer at the bottom of the pile foundation. It is the key part of the pile foundation for transmitting vertical loads. Its core function is to transfer the load of the superstructure to the bearing soil at the pile tip through the pile body. The load is borne by the supporting resistance of the soil at the pile tip and the frictional resistance between the side of the pile body and the soil.

[0027] Then, the probe, equipped with a cone tip resistance sensor, a sidewall friction cylinder, and a pore water pressure sensor, is driven into the formation at a constant speed. During this process, the data acquisition system continuously records the changes in cone tip resistance qc, sidewall friction resistance fs, and pore water pressure u2 with depth.

[0028] Among them, cone tip resistance represents the soil resistance per unit area at the probe cone tip; sidewall friction represents the frictional resistance per unit area at the probe sidewall friction cylinder; and pore water pressure represents the pore water pressure in the soil layer measured at a specific position behind the cone shoulder during penetration.

[0029] Then, the collected raw data is preprocessed, and mathematical methods such as moving average are used to eliminate abnormal peaks caused by gravel and small obstacles in the data, so as to obtain the CPTU curve, which includes smooth and continuous curves of cone tip resistance, sidewall friction and pore water pressure as a function of depth.

[0030] Step 102: Collect undisturbed soil samples at key depths in the pile location area and determine the soil parameters of the undisturbed soil samples.

[0031] The critical depth can be determined based on the characteristic points of the real-time or preliminary CPTU curves obtained in the first step. These characteristic points include: interfaces indicating significant changes in soil layers where qc values ​​change abruptly, and regions of different pore water pressure responses indicated by significant increases or decreases in u2.

[0032] The critical depth includes a first critical depth determined based on the cone tip resistance and pore water pressure in the CPTU curve, and a second critical depth where the pre-set pile end bearing layer is located.

[0033] Specifically, the pre-defined pile tip bearing layer refers to the soil layer range selected in advance during the pile foundation design stage based on engineering geological survey data and superstructure load requirements, which serves as the load support for the pile tip; it specifically includes a horizontal range and a depth range, and the depth range is the second critical depth.

[0034] Preferably, based on the characteristic points of the change curve, a first critical depth is determined, and target undisturbed soil samples are collected at the first critical depth and the second critical depth; the natural water content, liquid limit and plastic limit of the target undisturbed soil sample are measured, and the water content ratio of the target undisturbed soil sample is calculated; the water content ratio, natural water content, liquid limit and plastic limit at the same depth are paired to form the soil parameters.

[0035] The obtained undisturbed soil samples were immediately sealed and sent to the laboratory for testing according to the national standard geotechnical testing methods. The natural moisture content w, liquid limit wl, and plastic limit wP were determined. The natural moisture content w is the ratio of the mass of water to the mass of solid particles in the soil sample. The liquid limit wl is the boundary moisture content at which the soil changes from a plastic state to a fluid state, and can be determined using the cone penetrometer method. The plastic limit wP is the boundary moisture content at which the soil changes from a plastic state to a semi-solid state, and can be determined using the strip rolling method.

[0036] Among them, the water content ratio aw of the original soil sample is the ratio of the natural water content w to the liquid limit wl, which reflects the current soft and hard plastic state of the red clay and is a key indicator related to its mechanical behavior.

[0037] Specifically, for each soil sample collected at a critical depth and its measured water content (aw), preprocessed data of cone tip resistance (qc), sidewall friction (fs), and pore water pressure (u2) at that depth are extracted from the CPTU curve at the same geographical location and corresponding depth. This generates a series of discrete data pairs with strict location and depth correspondence: (depth z: aw, qc, fs, u2).

[0038] Step 103: Based on the soil parameters, generate a three-dimensional partition map of the plastic state of the red clay in the pile location area.

[0039] Preferably, based on the soil parameters, the normalized cone tip resistance and normalized friction ratio at each key depth can be calculated; based on the normalized cone tip resistance and normalized friction ratio, the soil behavior type index can be calculated to obtain a soil behavior type index profile; based on the soil parameters, a site-specific statistical relationship model between the soil behavior type index and the measured water content can be established; the continuous soil behavior type index profile can be input into the statistical relationship model to obtain an equivalent water content profile; according to the preset mapping relationship between the equivalent water content and the plastic state, the equivalent water content profile can be transformed into a plastic state profile; based on the plastic state profile and the soil parameters, the three-dimensional zoning map can be generated.

[0040] For each depth point data pair, the normalized cone tip resistance Qt and the normalized friction ratio Fr are calculated.

[0041] Specifically, the formula for calculating the normalized cone tip resistance Qt includes: ; ; ; ; in, The corrected total cone tip resistance, This represents the total overburden pressure at that depth. This represents the effective overburden pressure at that depth; γ is the probe area ratio coefficient, a known constant related to the probe geometry; γ is the unit weight of the soil layer, which can be estimated based on the soil conditions; u0 is the hydrostatic pressure at that depth.

[0042] Specifically, the formula for calculating the normalized friction ratio Fr includes: ;in, Fr represents the net cone tip resistance, expressed as a percentage, and reflects the frictional characteristics of the soil.

[0043] Then, calculate the soil behavior type index. The calculation formula is a classic formula proposed and improved by Robertson et al., and the soil behavior type index is an internationally recognized soil classification index based on CPTU.

[0044] The above calculations yield a continuous Ic(z) curve showing how the Ic value changes with depth z, which can be used to identify soil types such as clay, silt, and sand.

[0045] Then, for the depth in each data pair Extracting identical depths from continuous Ic(z) curves place And obtain the exact same depth from the data pair obtained in step 102. water content at the location Plot these data points in a coordinate system with Ic as the X-axis and aw as the Y-axis; use regression analysis to establish an empirical Ic-aw relationship model for the site.

[0046] For example, by using methods such as linear regression, multinomial regression, or exponential regression to determine the optimal fitting model based on the distribution of data points, a linear model may be obtained: .

[0047] The water content (aw) of clay directly determines its plastic state, such as fluid plastic, soft plastic, or plastic. In specific red clay regions, there is a significant statistical correlation between Ic and aw. Generally, a larger Ic indicates a more fine-grained, plastic behavior in the soil, and a larger aw value indicates a softer soil. This correlation is not globally universal but site-specific. The establishment of this model allows the universal soil classification index Ic to be localized and specialized into a proxy index that can quantitatively indicate the core state parameter aw of red clay.

[0048] Then, the entire continuous Ic(z) curve is substituted into the site-specific Ic-aw correlation model. For the Ic value at each depth point, the corresponding aw value is calculated through the model, which is named "equivalent water cut ratio" and denoted as aw-eq.

[0049] This process yields a continuous aw-eq(z) profile curve, enabling the generation of a continuous, high-resolution in-situ state profile from limited, discrete indoor experimental aw data. This solves the problem of sparse data points and difficulty in reflecting true variation in general techniques.

[0050] Then, based on the correspondence table between the plastic state and water content (aw) of red clay in national or industry standards, the threshold for classifying different plastic states of red clay can be determined. For example, aw-eq > 1.0 for the fluid plastic state; aw-eq between 0.85 and 1.0 for the soft plastic state; aw-eq between 0.65 and 0.85 for the plastic state; and aw-eq ≤ 0.65 for the hard plastic state.

[0051] Then, the continuous aw-eq(z) curve is transformed into a continuous plasticity state code curve that varies with depth, according to the division threshold. For example, each depth point is assigned a value of 1-flowing plastic, 2-soft plastic, 3-plastic, and 4-hard plastic.

[0052] Then, for a single CPTU borehole, a strip map of its depth-plastic state can be plotted; for multiple CPTU test points within a site, the depth-plastic state information of each borehole is integrated in three-dimensional space. Specifically, the plastic state of untested locations can be inferred using spatial interpolation techniques, ultimately generating a three-dimensional zoning map of the plastic state of red clay across the entire pile location area.

[0053] Step 104: Obtain the measured values ​​of pile end resistance in different plastic state zones, and based on the measured values ​​of pile end resistance at the same depth and soil parameters, establish a pile end resistance calculation sub-model applicable to different plastic state zones, forming a calculation sub-model library.

[0054] Preferably, the measured values ​​of pile end resistance within different plastic state zones are obtained through deep plate load tests or static load tests on pile foundations; the spatial location and pile end elevation of each test point corresponding to the measured value of pile end resistance are determined; the main plastic state category affecting the depth of the test point is identified from the three-dimensional zoning map; and the normalized cone tip resistance and equivalent water content at the same depth are extracted; the test data are grouped according to the plastic state category; for each group of test data, a multiple regression analysis is performed with the normalized cone tip resistance and the equivalent water content as independent variables and the measured value of pile end resistance as the dependent variable to establish a sub-model for calculating pile end resistance under the corresponding plastic state category; and the sub-models for calculating all plastic state categories are collected to form the sub-model library.

[0055] The steps of the deep plate load test include: selecting a suitable depth in a representative geological unit corresponding to different plastic states, excavating to the predetermined test surface and leveling it; installing a circular or square rigid bearing plate of a certain size, and applying graded loads to it through a reaction device; recording the settlement of the bearing plate under each load level and plotting the pressure-settlement (ps) curve; then determining the proportional limit load or ultimate load according to industry standards, and determining the characteristic value pb of the measured pile end resistance of the soil layer at that depth from the ps curve.

[0056] The steps of the static load test for pile foundation include: constructing a test pile with design parameters similar to those of a large-diameter engineering pile at the test site; conducting a vertical compressive static load test on the test pile, loading it step by step through a reaction device, and measuring the settlement at the top of the pile; from the load-settlement (Qs) curve obtained from the test, combined with the axial force test data of the pile body, separating the load borne by the pile end as the total resistance at the pile end, and then dividing it by the pile end area to calculate the measured average pile end resistance characteristic value pb.

[0057] It should be noted that pile end resistance is a physical and mechanical indicator, referring to the maximum resistance per unit area that the soil at the pile end can provide when it reaches its ultimate failure state. The characteristic value of pile end resistance is a statistically representative value, serving as a bridge between physical facts and design specifications. Specifically, it is determined based on statistical principles, through statistical analysis of experimental pile end resistance values, to represent a certain quantile value representing the resistance level of the soil layer. It is an intermediate parameter transitioning from the physical limit value to the usable design value. The design end resistance value is an engineering design parameter that can be directly used for calculation. Specifically, it is obtained by substituting the characteristic value of pile end resistance into the design expression specified in the specification and dividing by the corresponding partial factor. It directly participates in the calculation of the ultimate limit state of bearing capacity.

[0058] Then, for each point where end resistance testing is conducted in the pile location area, its three-dimensional coordinates and bottom elevation are input into the three-dimensional zoning map of the plastic state of red clay. The main soil layers in contact with the bottom of the test point and their plastic state categories are obtained, and the distribution weights of the plastic state of each soil layer within the influence depth range of the test point are extracted. The influence depth range of the test point is 1.5 times the pile diameter below the pile tip.

[0059] From the data of the CPTU borehole closest to the test point, extract the original CPTU data of the soil layer corresponding to the bottom elevation of the test point, and calculate the normalized cone tip resistance qt and the equivalent water content aw-eq of the soil layer at that location. The corresponding calculation formula can be found in step 103, and will not be repeated here.

[0060] Then, all the obtained test point data (pb, qt, aw-eq) are grouped according to their respective main plastic state zones. For example, all test data mainly located in the plastic state zone are grouped into the plastic state group. If the test point is in the state transition zone, its data is weighted and assigned to the corresponding group according to the thickness weight of each state soil layer within the influence depth, or it is discarded as data in the fuzzy zone.

[0061] Then, statistical analysis is performed independently on the data within each plastic state group. Specifically, normalized cone tip resistance qt and equivalent water content aw-eq can be used as independent variables, and the measured pile end resistance characteristic value pb can be used as the dependent variable. Using methods such as least squares, an independent end resistance prediction sub-model can be established for each group.

[0062] The model form can be selected based on the data relevance; for example, a binary linear sub-model can be expressed as follows: ,in, The characteristic value of the pile end resistance for the soil layer belonging to the i-th plastic state is the predicted value. , , These are model coefficients, which have different values ​​in models grouped by different plastic states.

[0063] After modeling all the plastic state groups, these models can be stored together to obtain a sub-model library for calculating end resistance.

[0064] Step 105: Based on the design pile tip elevation of the target pile, extract the soil plasticity state and soil parameters within the corresponding pile tip influence depth range from the three-dimensional partition map, and call the corresponding calculation sub-model to calculate the pile tip resistance characteristic value after the target pile is deployed at the pile position.

[0065] Among them, the key parameters of the specific engineering pile to be designed, i.e. the target pile, input by the staff can be obtained, including the design pile tip elevation and pile diameter of the target pile.

[0066] Preferably, based on the design pile tip elevation of the target pile, the soil plasticity state and soil parameters within the corresponding pile tip influence depth range are extracted from the three-dimensional zoning map, and the corresponding calculation sub-model is called to calculate the pile tip resistance characteristic value after the target pile is deployed at the pile location. This includes: obtaining the design pile tip elevation and pile diameter of the target pile; determining the pile tip influence depth range based on the design elevation and pile diameter; extracting soil layer information within the pile tip influence depth range from the three-dimensional zoning map, including the plasticity state category, layer thickness, normalized cone tip resistance, and equivalent water content of each soil layer; for each soil layer, calling the corresponding calculation sub-model from the calculation sub-model library according to its plasticity state category, substituting the corresponding normalized cone tip resistance and equivalent water content, and calculating the unit end resistance contribution value of the soil layer; and calculating the pile tip resistance characteristic value based on the unit end resistance contribution value, layer thickness, and preset weighting coefficient of each soil layer.

[0067] Based on pile foundation engineering theory and engineering experience, the soil within a certain depth range that contributes to the supporting resistance at the pile tip can be determined. This depth range is usually referred to as the pile tip influence depth. The formula for calculating the pile tip influence depth is as follows: Where k is an empirical coefficient and D is the pile diameter. The depth of influence at the pile tip.

[0068] For example, the depth of influence at the pile tip can be from the pile tip elevation. Extend downwards The range.

[0069] Then, the core coordinates (X, Y) of the target pile and the calculated depth range can be input into a three-dimensional partition map of the plastic state of red clay, generating a virtual borehole profile along the depth direction based on these core coordinates. This profile is not the actual drilling result, but a high-resolution, continuous state prediction profile obtained by spatial interpolation of data from surrounding CPTU test points.

[0070] Analyzing the virtual borehole profile, the soil within the calculated depth range is divided into several homogeneous sublayers based on the boundary of plastic state variation. For each homogeneous sublayer, its thickness is extracted. Plastic state category And read the normalized cone tip resistance corresponding to the center point of the sublayer from the model. and equivalent water content .

[0071] Then, for each homogeneous sublayer, the calculation sub-model corresponding to its plastic state category is called to calculate its unit end resistance contribution value, i.e., the unit end resistance characteristic value; then, a weighted average is performed based on the layer thickness of each soil layer to calculate the overall pile end resistance characteristic value, i.e., the pile end resistance characteristic value of the target pile after deployment at the pile location. The calculation formula is as follows: ; in, This represents the overall characteristic value of pile end resistance. Let the unit end resistance contribution value of layer j be . Let j be the layer thickness; is the weighting coefficient for layer j, which reflects the relative contribution of the soil layer to the total resistance at the pile tip and can be related to the plastic state or stiffness of the soil layer.

[0072] Preferably, the value of the weighting coefficient is related to the plasticity state category of the soil layer, wherein the weighting coefficient of the stiff plastic soil layer is higher than that of the plastic soil layer, and the weighting coefficient of the plastic soil layer is higher than that of the soft plastic soil layer.

[0073] For example, λ=1.2 for stiff plastic soil layer, λ=1.0 for plastic soil layer, λ=0.8 for soft plastic soil layer, and λ=0 for fluid plastic soil layer.

[0074] Preferably, after the corresponding calculation sub-model is invoked to calculate the characteristic value of the pile end resistance after the target pile is deployed at the pile position, the characteristic value of the single pile vertical bearing capacity of the target pile can be calculated based on the pile end resistance.

[0075] The formula for calculating the characteristic value of the vertical bearing capacity of a single pile can be: ,in, This represents the characteristic value of the vertical bearing capacity of a single pile. The area of ​​the pile tip bottom. Let be the characteristic value of the pile side resistance of the i-th soil layer. Let be the length of the pile in the i-th soil layer.

[0076] In this embodiment, by dynamically correlating CPTU continuous in-situ test parameters with red clay soil parameters, the mechanical properties of the pile tip soil are identified and zoned, overcoming the shortcomings of traditional methods that rely on sparse and disturbed samples. Simultaneously, differentiated calculation sub-models are established for different plastic state zones, transforming the end resistance value from a single empirical value to a dynamically calculated value based on the actual soil state. This improves the accuracy and reliability of end resistance calculation in highly variable soils like red clay, effectively avoiding unreasonable pile length design due to improper parameter values. Thus, while ensuring project safety, project costs are optimized and construction risks are reduced.

[0077] The method provided in the embodiments of this application has been described above. The system provided in the embodiments of this application will be described below.

[0078] Please see Figure 2 , Figure 2 This is a schematic diagram of a red clay pile foundation parameter determination system provided in an embodiment of this application, as shown below. Figure 2 As shown, the system 20 includes: CPTU module 201 is used to perform static cone penetration test (CPTU) in the pile location area to obtain the CPTU curve; Measurement module 202 is used to collect target undisturbed soil samples at key depths in the pile location area and measure the soil parameters of the target undisturbed soil samples; wherein, the key depths include a first key depth determined based on the cone tip resistance and pore water pressure in the CPTU curve, and a second key depth where the preset pile end bearing layer is located; The generation module 203 is used to generate a three-dimensional zoning map of the plastic state of red clay in the pile location area based on the soil parameters. Modeling module 204 is used to obtain the measured values ​​of pile end resistance in different plastic state zones, and based on the measured values ​​of pile end resistance at the same depth and soil parameters, to establish a pile end resistance calculation sub-model applicable to different plastic state zones, forming a calculation sub-model library; The calculation module 205 is used to extract the soil plasticity state and soil parameters within the corresponding pile tip influence depth range from the three-dimensional partition map based on the design pile tip elevation of the target pile, and call the corresponding calculation sub-model to calculate the pile tip resistance characteristic value of the target pile after it is deployed at the pile position.

[0079] Preferably, the CPTU curve includes curves showing the variation of cone tip resistance, sidewall friction, and pore water pressure with depth; the measurement unit 202 is specifically used to determine the first critical depth based on the characteristic points of the variation curve, and to collect target undisturbed soil samples at the first critical depth and the second critical depth; the natural water content, liquid limit, and plastic limit of the target undisturbed soil sample are measured, and the water content ratio of the target undisturbed soil sample is calculated; the water content ratio, natural water content, liquid limit, and plastic limit at the same depth are paired to form the soil parameters.

[0080] Preferably, the generation module 203 is specifically used to calculate the normalized cone tip resistance and normalized friction ratio at each key depth based on the soil parameters; calculate the soil behavior type index based on the normalized cone tip resistance and normalized friction ratio to obtain a soil behavior type index profile; establish a site-specific statistical relationship model between the soil behavior type index and the measured water content based on the soil parameters; input the continuous soil behavior type index profile into the statistical relationship model to invert and obtain an equivalent water content profile; transform the equivalent water content profile into a plastic state profile according to a preset mapping relationship between the equivalent water content and the plastic state; and generate the three-dimensional zoning map based on the plastic state profile and the soil parameters.

[0081] Preferably, the modeling module 204 is specifically used to obtain the measured values ​​of pile end resistance in different plastic state zones through deep plate load tests or pile static load tests; determine the spatial location and pile end elevation of each test point corresponding to the measured value of the pile end resistance; identify the main plastic state category affecting the depth of the test point from the three-dimensional zoning map; and extract the normalized cone tip resistance and equivalent water content at the same depth; group the test data according to the plastic state category; for each group of test data, perform multiple regression analysis with the normalized cone tip resistance and the equivalent water content as independent variables and the measured value of the pile end resistance as the dependent variable; establish a pile end resistance calculation sub-model under the corresponding plastic state category; and collect all the calculation sub-models for the plastic state categories to form the calculation sub-model library.

[0082] Preferably, the calculation module 205 is specifically used to obtain the design elevation and diameter of the target pile tip; based on the design elevation and pile diameter, determine the depth range of the pile tip influence; using the pile center coordinates of the target pile as an index, extract soil layer information within the corresponding depth range from the three-dimensional partition map, including the plasticity state category, layer thickness, normalized cone tip resistance and equivalent water content of each soil layer; for each soil layer, call the corresponding calculation sub-model from the calculation sub-model library according to its plasticity state category, substitute the corresponding normalized cone tip resistance and equivalent water content, and calculate the unit end resistance contribution value of the soil layer; based on the unit end resistance contribution value, layer thickness and preset weight coefficient of each soil layer, calculate the pile tip resistance.

[0083] Preferably, the value of the weighting coefficient is related to the plasticity state category of the soil layer, wherein the weighting coefficient of the stiff plastic soil layer is higher than that of the plastic soil layer, and the weighting coefficient of the plastic soil layer is higher than that of the soft plastic soil layer.

[0084] Preferably, the calculation module 205 is also used to calculate the characteristic value of the vertical bearing capacity of the target pile based on the pile end resistance.

[0085] The red clay pile foundation parameter determination system provided in this application embodiment can be understood by referring to the relevant content in the foregoing method embodiment section, and will not be repeated here.

[0086] like Figure 3 As shown, Figure 3 This is a schematic diagram of a possible logical structure of a computing device provided in an embodiment of this application. The computing device 30 includes a processor 301, a communication interface 302, a memory 303, and a bus 304. The processor 301, the communication interface 302, and the memory 303 are interconnected via the bus 304. In an embodiment of this application, the processor 301 is used to control and manage the operation of the computing device 30. For example, the processor 301 is used to execute... Figure 1The steps in the embodiments and / or other processes used in the techniques described herein. Communication interface 302 is used to support communication by computing device 30. Memory 303 is used to store program code and data of computing device 30.

[0087] The processor 301 can be a central processing unit, a general-purpose processor, a digital signal processor, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. It can implement or execute various exemplary logic blocks, modules, and circuits described in conjunction with the disclosure of this application. The processor can also be a combination that implements computing functions, such as a combination of one or more microprocessors, a combination of a digital signal processor and a microprocessor, etc. The bus 304 can be a peripheral component interconnect (PCI) bus or an extended industry standard architecture (EISA) bus, etc. The bus can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Figure 3 The bus is represented by a single thick line, but this does not mean that there is only one bus or one type of bus.

[0088] In another embodiment of this application, a computer-readable storage medium is also provided, the computer-readable storage medium including instructions that, when executed on a computer, cause the computer to perform the above-described... Figure 1 The method described in the embodiments.

[0089] Those skilled in the art will recognize that the units of the various examples described in connection with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of the invention.

[0090] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0091] In the embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative. For instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the displayed or discussed mutual couplings, direct couplings, or communication connections may be through some interfaces; indirect couplings or communication connections between devices or units may be electrical, mechanical, or other forms.

[0092] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0093] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0094] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, read-only memory (ROM), random access memory (RAM), portable hard drives, magnetic disks, or optical disks.

[0095] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A method for determining parameters of red clay pile foundations, characterized in that, The method includes: Static cone penetration test (CPTU) was performed in the pile location area to obtain the CPTU curve; Untouched soil samples were collected at key depths in the pile location area, and soil parameters of the untouched soil samples were measured. The key depths include a first key depth determined based on the cone tip resistance and pore water pressure in the CPTU curve, and a second key depth where the pre-set pile end bearing layer is located. Based on the soil parameters, a three-dimensional zoning map of the plastic state of the red clay in the pile location area is generated; Obtain measured values ​​of pile end resistance in different plastic state zones, and based on the measured values ​​of pile end resistance at the same depth and soil parameters, establish pile end resistance calculation sub-models applicable to different plastic state zones, forming a calculation sub-model library; Based on the design pile tip elevation of the target pile, the plastic state and soil parameters of the soil layer within the corresponding pile tip influence depth range are extracted from the three-dimensional partition map, and the corresponding calculation sub-model is called to calculate the pile tip resistance characteristic value after the target pile is deployed at the pile position.

2. The method according to claim 1, characterized in that, The CPTU curve includes curves showing the changes in cone tip resistance, sidewall friction, and pore water pressure with depth; the collection of undisturbed soil samples at key depths in the pile location area, and the determination of soil parameters of the undisturbed soil samples, including: Based on the characteristic points of the change curve, a first critical depth is determined, and the target undisturbed soil sample is collected at the first critical depth and the second critical depth. The natural water content, liquid limit, and plastic limit of the target undisturbed soil sample were determined, and the water content ratio of the target undisturbed soil sample was calculated. The soil parameters are formed by pairing the water content ratio, natural water content, liquid limit, and plastic limit at the same depth.

3. The method according to claim 2, characterized in that, The process of generating a three-dimensional zoning map of the plastic state of the red clay in the pile location area based on the soil parameters includes: Based on the soil parameters, the normalized cone tip resistance and normalized friction ratio at each key depth were calculated. Based on the normalized cone tip resistance and the normalized friction ratio, the soil behavior type index is calculated to obtain the soil behavior type index profile. Based on the soil parameters, a site-specific statistical relationship model between the soil behavior type index and the water content ratio is established. The soil behavior type index profile is input into the statistical relationship model to obtain the equivalent water content profile. Based on the preset mapping relationship between equivalent water content and plastic state, the equivalent water content profile is transformed into a plastic state profile. The three-dimensional zoning map is generated based on the plastic state profile and the soil parameters.

4. The method according to claim 3, characterized in that, The process involves acquiring measured values ​​of pile end resistance within different plasticity state zones, and based on these measured values ​​and soil parameters at the same depth, establishing sub-models for calculating pile end resistance applicable to different plasticity state zones, thus forming a sub-model library, including: The measured values ​​of pile end resistance in different plastic state zones were obtained by deep plate load test or pile static load test. Determine the spatial location and pile end elevation of each test point corresponding to the measured value of the pile end resistance, confirm the main plastic state category of the test point corresponding to the depth of influence in the three-dimensional partition map, and extract the normalized cone tip resistance and equivalent water content of the same depth. The test data were grouped according to the plastic state category. For each group of test data, the normalized cone tip resistance and the equivalent water content ratio were used as independent variables, and the measured value of the pile end resistance was used as the dependent variable. A multiple regression analysis was performed to establish a sub-model for calculating the pile end resistance under the corresponding plastic state category. The computational sub-models for all plastic state categories are compiled to form the computational sub-model library.

5. The method according to any one of claims 1-4, characterized in that, The design pile tip elevation based on the target pile is used to extract the soil plasticity state and soil parameters within the corresponding pile tip influence depth range from the three-dimensional zoning map, and the corresponding calculation sub-model is called to calculate the pile tip resistance characteristic value after the target pile is deployed at the pile location, including: Obtain the design elevation of the pile tip and the pile diameter of the target pile; Based on the design elevation and pile diameter, determine the range of the pile tip influence depth; Soil layer information within the pile tip influence depth range is extracted from the three-dimensional partition map, including the plastic state category, layer thickness, normalized cone tip resistance and equivalent water content of each soil layer; For each soil layer, the corresponding calculation sub-model is called from the calculation sub-model library based on its plasticity state category, and the corresponding normalized cone tip resistance and equivalent water content are substituted to calculate the unit end resistance contribution value of the soil layer. Based on the unit end resistance contribution value of the soil layer, the layer thickness, and the preset weighting coefficient, the characteristic value of the pile end resistance is calculated.

6. The method according to claim 5, characterized in that, The weighting coefficient is related to the plasticity state of the soil layer, with the weighting coefficient of the stiff plastic soil layer being higher than that of the plastic soil layer, and the weighting coefficient of the plastic soil layer being higher than that of the soft plastic soil layer.

7. The method according to any one of claims 1-4, characterized in that, After the method calls the corresponding computational sub-model to calculate the characteristic value of the pile end resistance of the target pile after it is deployed at the pile location, the method further includes: The characteristic value of the vertical bearing capacity of a single pile of the target pile is calculated based on the characteristic value of the pile end resistance.

8. A system for determining parameters of red clay pile foundations, characterized in that, The system, applied to the method of any one of claims 1-7, comprises: The CPTU module is used to perform static cone penetration test (CPTU) in the pile location area to obtain the CPTU curve; The measurement module is used to collect target undisturbed soil samples at key depths in the pile location area and measure the soil parameters of the target undisturbed soil samples; wherein, the key depths include a first key depth determined based on the cone tip resistance and pore water pressure in the CPTU curve, and a second key depth where the preset pile end bearing layer is located; The generation module is used to generate a three-dimensional partition map of the plastic state of red clay in the pile location area based on the soil parameters. The modeling module is used to obtain the measured values ​​of pile end resistance in different plastic state zones, and based on the measured values ​​of pile end resistance at the same depth and soil parameters, to establish pile end resistance calculation sub-models applicable to different plastic state zones, forming a calculation sub-model library; The calculation module is used to extract the soil plasticity state and soil parameters within the corresponding pile tip influence depth range from the three-dimensional partition map based on the design pile tip elevation of the target pile, and call the corresponding calculation sub-model to calculate the pile tip resistance characteristic value of the target pile after it is deployed at the pile position.

9. A computing device, characterized in that, include: Memory, used to store programs; A processor for loading the program to perform the method as described in any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium includes a stored program, wherein, when the program is executed, it controls the device on which the computer-readable storage medium is located to perform the method of any one of claims 1-7.

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