Rapid detection system of composite foundation bearing capacity based on adaptive variable diameter identification algorithm

Abstract

The present invention belongs to the field of measurement and data processing technology, and specifically relates to a composite foundation bearing capacity rapid detection system based on an adaptive variable diameter identification algorithm, the system comprising: a distributed optical fiber sensor array, a foundation strain feature extraction part, a foundation dynamic coupling calculation part and a bearing capacity calculation part; the distributed sensor array comprises a plurality of optical fiber sensors arranged in an array and arranged on the foundation to construct a three-dimensional strain field distribution; the foundation strain feature extraction part is used to construct a foundation dynamic stiffness matrix based on the three-dimensional strain field distribution; extract variable diameter features; the foundation dynamic coupling calculation part is used to construct a nonlinear constitutive relationship based on the three-dimensional strain field distribution; calculate the ultimate bearing capacity; the bearing capacity calculation part is used to calculate the current bearing capacity based on the ultimate bearing capacity. The present invention can improve detection accuracy and efficiency, enhance adaptability to complex working conditions, and significantly improve the safety and reliability of foundation engineering.

Description

Technical Field

[0001] The invention belongs to the technical field of measurement and data processing, and in particular relates to a composite foundation bearing capacity rapid detection system based on an adaptive variable diameter identification algorithm. Background Art

[0002] The evaluation and detection of foundation bearing capacity is an extremely important research topic in the field of civil engineering, and its results are directly related to the safety and stability of engineering structures. In actual engineering, the foundation is often in a complex stress state, accompanied by changes in time, space and environmental factors. The accurate evaluation of its bearing capacity is crucial for foundation design and construction control. However, the current foundation bearing capacity detection technology still has many limitations and is difficult to meet the needs of modern complex engineering.

[0003] Traditional calculation methods for foundation bearing capacity are mainly based on theoretical models and field test methods. Common methods include the classical Mohr-Coulomb theory and Tresca theory, which predict bearing capacity by soil cohesion, internal friction angle and effective stress. Although these methods have a certain theoretical basis, they often assume that the mechanical behavior of the foundation is static and uniformly distributed, ignoring the complex characteristics of the foundation under actual stress conditions. Field test methods (such as static load test and dynamic load test) are important means to evaluate foundation bearing capacity. These methods directly load the bearing capacity of the soil in the vertical direction to obtain the ultimate bearing capacity of the foundation. However, field tests have significant limitations: the test equipment is large, expensive, and the cycle is long, and the test results can only reflect the soil characteristics of a specific location, and it is difficult to fully reflect the mechanical behavior of the entire foundation area. At the end of the 20th century, the development of distributed sensing technology provided a new way to detect foundation bearing capacity. The introduction of fiber Bragg grating (FBG) sensors and optical time domain reflectometry (OTDR) technology enables engineers to monitor the strain and displacement distribution of the foundation in real time through distributed sensor arrays. However, existing distributed sensing technologies focus more on monitoring the single-directional characteristics of stress or deformation, and lack a comprehensive analysis of the dynamic characteristics and spatial coupling behavior of the foundation. In addition, creep models and consolidation models proposed in recent years have been used to describe the deformation behavior of the foundation under long-term loads. For example, one-dimensional consolidation theory (such as Taylor's consolidation equation) is widely used to analyze pore water pressure dissipation and soil settlement. However, these models usually simplify the spatial mechanical properties of the soil and fail to fully consider the multi-axial coupling behavior of the soil, complex nonlinear response, and the influence of environmental factors (such as temperature and humidity). Summary of the invention

[0004] In view of this, the main purpose of the present invention is to provide a composite foundation bearing capacity rapid detection system based on an adaptive variable diameter identification algorithm. The present invention can dynamically capture the spatial coupling characteristics, long-term deformation laws and environmental factors of the foundation, and solve the limitations of traditional methods in dynamic response, spatial distribution and multi-factor coupling analysis. Its beneficial effects are to improve detection accuracy and efficiency, enhance adaptability to complex working conditions, and significantly improve the safety and reliability of foundation engineering.

[0005] The technical solution adopted by the present invention is as follows:

[0006] A composite foundation bearing capacity rapid detection system based on an adaptive variable diameter identification algorithm, the system comprising: a distributed optical fiber sensor array, a foundation strain feature extraction part, a foundation dynamic coupling calculation part and a bearing capacity calculation part; the distributed sensor array comprises a plurality of optical fiber sensors arranged in an array and arranged on the foundation, each optical fiber sensor collects foundation strain data and constructs a three-dimensional strain field distribution; the foundation strain feature extraction part is used to construct a foundation dynamic stiffness matrix based on the three-dimensional strain field distribution; the variable diameter feature is extracted from the foundation dynamic stiffness matrix by Fourier-Laplace transform; the foundation dynamic coupling calculation part is used to establish a foundation creep-consolidation coupling model based on the three-dimensional strain field distribution and the geological data of the foundation, and to construct a nonlinear constitutive relationship based on the creep-consolidation coupling model; the ultimate bearing capacity is calculated by combining the variable diameter feature and the nonlinear constitutive relationship; the bearing capacity calculation part is used to calculate the foundation stability coefficient based on the ultimate bearing capacity and considering the temperature effect, and calculate the current bearing capacity based on the stability coefficient and combining the variable diameter feature and the nonlinear constitutive relationship.

[0007] Furthermore, the optical fiber sensor is a fiber Bragg grating sensor or an optical time domain reflectometry sensor; the geological data include: soil damping ratio, soil elastic modulus, soil density, foundation soil layer thickness, soil porosity, soil permeability, water bulk density, soil internal friction angle, soil viscosity coefficient, soil cohesion and soil temperature.

[0008] Furthermore, the three-dimensional strain field distribution Use the following formula to express it:

[0009] ;

[0010] in, is the soil damping ratio; is the soil density; is the elastic modulus of soil; is an integer subscript index; is an integer subscript index; is the number of fiber optic sensors in the row direction of the distributed fiber optic sensing array; is the number of optical fiber sensors in the column direction of the distributed optical fiber sensing array; The first distributed optical fiber sensor array Row, No. The displacement measured by the optical fiber sensors in the series; Represents the second-order partial derivative of the displacement in the X-axis direction and the Y-axis direction; Represents the second-order partial derivative of the displacement in the X-axis direction and the Z-axis direction; Represents the second-order partial derivative of the displacement in the Y-axis direction and the Z-axis direction; represents the distance of the sensor array from the foundation surface; is the shear wave propagation velocity in soil; is the frequency of the light wave of the fiber optic sensor.

[0011] Furthermore, the foundation dynamic stiffness matrix The formula is as follows:

[0012] ;

[0013] in, express The second-order partial derivative in the X-axis direction; express The second-order partial derivative in the Y-axis direction; express The second-order partial derivative in the Z-axis direction; express Second-order partial derivatives in the X-axis and Y-axis directions; express Second-order partial derivatives in the X-axis and Z-axis directions; express Second-order partial derivatives in the Y-axis and X-axis directions; express Second-order partial derivatives in the Y-axis and Z-axis directions; express Second-order partial derivatives in the Z-axis and X-axis directions; express Second-order partial derivatives in the Z-axis and Y-axis directions; Indicates the thickness of the foundation soil layer; is the boundary surface of the strain field, defined as the boundary surface of the distributed optical fiber sensor array.

[0014] Furthermore, the variable diameter feature is extracted from the foundation dynamic stiffness matrix by Fourier-Laplace transform using the following formula:

[0015] ;

[0016] in, Representation calculation The determinant of ; represents Fourier transform; is the Laplace transform complex variable; is the specific gravity of water; is the soil permeability; is the position integral variable of the X-axis; is the position integral variable of the Y axis; is the Z-axis position integral variable.

[0017] Furthermore, the foundation creep-consolidation coupling model is calculated using the following formula:

[0018] ;

[0019] in, is the characteristic consolidation time, which is obtained by the following process: in the field loading test, the pore water pressure of the soil after loading is recorded as a function of time. The time of t is regarded as the characteristic consolidation time ; is the soil porosity ratio; is the drainage path length, i.e. the maximum distance of drainage of the foundation soil layer. For unidirectional drainage, it is the thickness of the foundation soil layer, and for bidirectional drainage, it is half of the thickness of the foundation soil layer; It is the interval between the current measurement time and the last measurement time of all sensors in the distributed optical fiber sensor array.

[0020] Furthermore, the nonlinear constitutive relation is expressed by the following formula:

[0021] ;

[0022] in, is the maximum shear stress; is the time-integrated variable; is the soil viscosity coefficient; is the friction angle within the soil; is the soil cohesion; is the soil temperature.

[0023] Furthermore, the ultimate bearing capacity is calculated by combining the variable diameter characteristics and the nonlinear constitutive relationship through the following formula:

[0024] ;

[0025] in, is the foundation pile length; is the ultimate bearing capacity.

[0026] Furthermore, the foundation stability coefficient is calculated based on the ultimate bearing capacity and considering the temperature effect through the following formula: :

[0027] ;

[0028] in, is the gas constant; is the average ground temperature.

[0029] Furthermore, the current bearing capacity is calculated by the following formula based on the stability coefficient, combined with the variable diameter characteristics and nonlinear constitutive relationship: :

[0030] ;

[0031] in, is the set standard variable diameter characteristic value; is the set standard elastic modulus.

[0032] By adopting the above technical solution, the present invention produces the following beneficial effects:

[0033] The present invention realizes high-precision real-time construction of the three-dimensional strain field of the foundation through a distributed optical fiber sensor array. Distributed optical fiber sensing technology, especially the combination of fiber Bragg grating (FBG) and optical time domain reflectometry (OTDR) sensors, can capture subtle strain changes in the foundation with high resolution and high sensitivity, and generate detailed three-dimensional strain field distribution maps. This technology breaks through the limitations of traditional point measurement sensors, realizes full coverage and dynamic monitoring of the strain state of the entire foundation area, and provides high-quality basic data for subsequent analysis.

[0034] The construction of three-dimensional strain field plays a core role in the present invention. By introducing Fourier-Laplace transform and dynamic stiffness matrix modeling, the system can extract key mechanical characteristics of the foundation from the three-dimensional strain field, especially the variable diameter characteristics and dynamic stiffness distribution. This method not only improves the accuracy of data processing, but also breaks through the limitations of traditional static stiffness analysis, enabling the system to capture the complex mechanical response of the foundation under dynamic loads.

[0035] The present invention organically combines the long-term deformation behavior of the foundation with the dynamic dissipation process of the pore water pressure through the creep-consolidation coupling model, and comprehensively reflects the deformation law of the foundation under long-term load. The model describes the comprehensive effect of creep strain and consolidation strain through mathematical expression. It not only considers the cumulative influence of time factors on foundation deformation, but also incorporates parameters such as drainage path, elastic modulus and characteristic consolidation time into the analysis framework. Compared with traditional models, the coupling model of the present invention has a high degree of dynamic adaptability. The introduction of the exponential decay function can describe the dynamic response characteristics of the foundation at different time stages, thereby more accurately predicting the long-term bearing capacity and stability of the foundation.

[0036] In addition, by updating the data collected by distributed sensors in real time, the model can dynamically adjust the analysis parameters and reflect the changes in the foundation state in real time. This technological breakthrough fills the gaps in the traditional static consolidation theory and the single creep model in practical engineering applications. The present invention further improves the ability to describe the complex mechanical behavior of the foundation by introducing nonlinear constitutive relations. The stress-strain relationship of the soil body usually has significant nonlinear characteristics, especially in the limit state, the shear strength, viscosity and internal friction angle of the soil body will change dynamically with the stress state. On the basis of the traditional Mohr-Coulomb theory, the present invention combines dynamic shear characteristics, temperature effects and time effects to construct a more realistic nonlinear constitutive relationship model. The model captures the shear behavior and stiffness change law of the foundation under multi-axial stress by dynamically coupling high-order displacement gradients and viscosity characteristics. In addition, the model also introduces time integral and temperature correction terms, which can accurately describe the influence of dynamic loading and environmental conditions on the bearing capacity of the foundation. This method not only significantly improves the accuracy of bearing capacity prediction, but also expands the applicability of the model in complex geological conditions and variable working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 A schematic diagram of the system structure of a composite foundation bearing capacity rapid detection system based on an adaptive variable diameter identification algorithm provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0038] All features disclosed in this specification, or steps in all methods or processes disclosed, except mutually exclusive features and / or steps, can be combined in any manner.

[0039] Any feature disclosed in this specification (including any additional claims and abstract), unless otherwise stated, may be replaced by other alternative features that are equivalent or have similar purposes. That is, unless otherwise stated, each feature is only an example of a series of equivalent or similar features.

[0040] Example 1: Reference Figure 1A composite foundation bearing capacity rapid detection system based on an adaptive variable diameter identification algorithm, the system comprising: a distributed optical fiber sensor array, a foundation strain feature extraction part, a foundation dynamic coupling calculation part and a bearing capacity calculation part; the distributed sensor array comprises a plurality of optical fiber sensors arranged in an array and arranged on the foundation, each optical fiber sensor collects foundation strain data and constructs a three-dimensional strain field distribution; the foundation strain feature extraction part is used to construct a foundation dynamic stiffness matrix based on the three-dimensional strain field distribution; the variable diameter feature is extracted from the foundation dynamic stiffness matrix by Fourier-Laplace transform; the foundation dynamic coupling calculation part is used to establish a foundation creep-consolidation coupling model based on the three-dimensional strain field distribution and the geological data of the foundation, and to construct a nonlinear constitutive relationship based on the creep-consolidation coupling model; the ultimate bearing capacity is calculated by combining the variable diameter feature and the nonlinear constitutive relationship; the bearing capacity calculation part is used to calculate the foundation stability coefficient based on the ultimate bearing capacity and considering the temperature effect, and calculate the current bearing capacity based on the stability coefficient and combining the variable diameter feature and the nonlinear constitutive relationship.

[0041] Specifically, the distributed optical fiber sensor array plays a vital role as a core component. Its basic principle is based on the scattering effect of optical signals in optical fibers, mainly including Brillouin scattering, Raman scattering and Rayleigh scattering. When the optical signal is transmitted through the optical fiber, the external strain and temperature changes will cause tiny disturbances inside the optical fiber. These disturbances will affect the propagation characteristics of the optical signal, which is specifically manifested as changes in the phase, frequency and intensity of the scattered light signal. Distributed optical fiber sensing technology can monitor the strain and temperature distribution along the length of the optical fiber in real time and continuously by detecting the changes in these scattered light signals, thereby constructing a detailed distribution map of the three-dimensional strain field. In the composite foundation bearing capacity rapid detection system of the present invention, multiple optical fiber sensors are precisely arranged at different positions and depths of the foundation to form a high-density sensor array. These optical fiber sensors are connected by advanced optical measuring instruments, and can capture the strain changes of the foundation during the stress process with micron-level accuracy. Due to the complex foundation structure and the variable stress state, it is difficult for traditional discrete sensors to fully cover the entire foundation area, while the distributed optical fiber sensor array provides more comprehensive and detailed strain data through its continuous monitoring characteristics. These data can not only reflect the instantaneous strain of the foundation at different locations, but also reveal the dynamic change trend of strain over time, providing a solid data foundation for subsequent bearing capacity analysis.

[0042] The working process of the fiber optic sensor array in the system is first to emit a high-frequency pulse light signal into the fiber optic sensor through a laser source. When the light signal propagates in the optical fiber, it encounters a small strain caused by the change in foundation stress, causing the light signal to scatter. Brillouin scattering is mainly used to measure the distribution changes of strain and temperature, and accurately calculate the local strain value by analyzing the frequency shift of the scattered light; Rayleigh scattering is used to reflect the microstructural changes in the optical fiber and provide high-resolution strain information. These scattered light signals are captured by highly sensitive detectors and transmitted to the data processing unit. After signal processing and demodulation, they are converted into strain data that can be used for analysis. The foundation strain feature extraction part in the system uses these high-precision strain data to construct the dynamic stiffness matrix of the foundation, which is an important parameter for evaluating the bearing capacity of the foundation. Through Fourier-Laplace transform, the system can extract the variable diameter feature from the dynamic stiffness matrix, that is, the regularity of the foundation stiffness changing with the radial direction. This process relies on the high-resolution and high-timeliness strain data provided by the distributed fiber optic sensor array, making the extraction of the variable diameter feature more accurate and reliable, thereby improving the accuracy and efficiency of the entire bearing capacity calculation. In addition, the application of distributed fiber optic sensor arrays enables the system to conduct real-time monitoring at different construction stages and under different working conditions, and timely capture subtle differences in foundation force changes and strain distribution. This real-time monitoring capability is of great significance for timely adjustment of construction plans and prevention of foundation instability. Compared with traditional discrete sensors, fiber optic sensor arrays not only improve the density and coverage of data collection, but also significantly reduce the cost and complexity of sensor deployment, and enhance the overall reliability and adaptability of the system.

[0043] The foundation strain feature extraction part uses the high-density, real-time strain data provided by the distributed fiber optic sensor array to construct a detailed three-dimensional strain field distribution map through precise spatial and temporal analysis. This strain field distribution map reflects the strain state of the foundation at different positions and depths, and reveals the response characteristics of the foundation under external loads. In order to further analyze the mechanical behavior of the foundation, the system needs to convert these complex strain data into a mathematical model that can describe the foundation stiffness characteristics, which leads to the construction of the dynamic stiffness matrix. The construction of the dynamic stiffness matrix is ​​to combine the strain data with the geological parameters of the foundation to form a matrix that can describe the stiffness change of the foundation under dynamic loads. This matrix not only considers the elastic and viscoelastic properties of the foundation material, but also incorporates the interlayer interaction of the foundation and the dynamic response of the overall structure. By analyzing the dynamic stiffness matrix, the stiffness distribution of the foundation under different stress states can be obtained, which is of great significance for evaluating the bearing capacity of the foundation. After the dynamic stiffness matrix is ​​constructed, the foundation strain feature extraction part further uses Fourier-Laplace transform to process it to extract the key variable diameter characteristics. The Fourier transform converts strain data from the time domain to the frequency domain, allowing the system to identify the periodicity and vibration characteristics of the foundation response; while the Laplace transform is used to analyze the attenuation characteristics of the foundation strain and capture the long-term response behavior of the foundation under dynamic loads. Through the combination of these two transformations, the system can comprehensively and accurately extract the regular characteristics of the foundation stiffness changing with the radial direction, which reflects the bearing capacity and deformation trend of the foundation at different spatial positions.

[0044] Compared with the prior art, traditional foundation strain analysis methods often rely on discrete sensors and static strain measurement, which makes it difficult to fully capture the complex response of the foundation under dynamic loads. The present invention realizes high-density and continuous strain monitoring through a distributed optical fiber sensor array, and combines the Fourier-Laplace transform technology to effectively improve the accuracy and efficiency of strain feature extraction. In particular, the introduction of the adaptive variable diameter recognition algorithm enables the system to autonomously adjust the analysis parameters according to the actual foundation conditions and strain distribution, further improving the flexibility and adaptability of feature extraction. In addition, the foundation strain feature extraction part fully considers the nonlinear behavior and complex mechanical properties of the foundation in the process of constructing the dynamic stiffness matrix and extracting the variable diameter feature. The foundation material exhibits different stiffness and deformation characteristics at different stress levels, and it is difficult for traditional linear analysis methods to accurately describe this nonlinear relationship. The system introduces nonlinear constitutive relations, combines dynamic stiffness matrices and variable diameter features, and realizes accurate modeling of the complex mechanical behavior of the foundation. This not only improves the accuracy of bearing capacity calculation, but also provides solid data support for subsequent foundation stability assessment.

[0045] The work of the foundation dynamic coupling calculation part depends on the three-dimensional strain field data extracted in the previous stage of the system. These data reflect the stress and deformation of the foundation under actual working conditions and are the basis for establishing the foundation dynamic coupling model. By deeply analyzing these strain data, the system can identify the strain response characteristics of the foundation at different positions and depths, and then derive the dynamic stiffness characteristics of the foundation. The dynamic stiffness characteristics are the key parameters that describe the change law of the foundation stiffness under dynamic loads. It not only reflects the elastic and viscoelastic properties of the foundation material, but also contains information about the internal structure and interlayer interaction of the foundation. When establishing the foundation creep-consolidation coupling model, the system comprehensively considers the creep behavior of the foundation material under long-term loads and the consolidation effect of the pore water pressure changing with time. The creep effect describes the gradual deformation of the foundation material under constant stress over time, while the consolidation effect reflects the dissipation process of the pore water pressure in the foundation. The coupling relationship between the two determines the overall response characteristics of the foundation under dynamic loads. By organically combining creep and consolidation effects, the system can more comprehensively simulate the complex behavior of the foundation under actual working conditions, thereby improving the accuracy of bearing capacity calculations.

[0046] In addition, the dynamic coupling calculation part of the foundation introduces nonlinear constitutive relations, which significantly improves the accuracy and applicability of the model. Traditional linear constitutive relations often cannot fully describe the nonlinear response of foundation materials under different stress levels, while nonlinear constitutive relations can more realistically reflect the mechanical properties of materials under different stress states. By combining nonlinear constitutive relations, the system can more accurately describe the stress-strain relationship of the foundation under dynamic loads, thereby improving the reliability of the ultimate bearing capacity calculation. In the actual calculation process, the dynamic coupling calculation part of the foundation not only needs to process a large amount of complex strain data and geological parameters, but also needs to use the adaptive variable diameter recognition algorithm to dynamically adjust the variable diameter characteristics. The adaptive variable diameter recognition algorithm can automatically identify the law of foundation stiffness changing with radial changes by analyzing the strain field distribution and geological data, and adjust the model parameters accordingly, making the calculation process more flexible and adaptable. The introduction of this algorithm not only improves the calculation efficiency, but also significantly improves the accuracy and reliability of bearing capacity assessment. When performing dynamic coupling calculations of the foundation, the system also fully considers the heterogeneity and complexity of the foundation. The foundation is usually composed of a variety of soil layers with different properties. Each layer of soil has different mechanical properties. This non-uniformity has an important impact on the overall bearing capacity of the foundation. The foundation dynamic coupling calculation part can accurately simulate the interaction and overall response between the soil layers by modeling the characteristics of different soil layers in detail, thereby achieving accurate evaluation of the bearing capacity under complex foundation conditions.

[0047] The basis of the bearing capacity calculation part is the solution of the ultimate bearing capacity, which essentially reflects the maximum load that the foundation can withstand when it reaches a state of destruction under the action of external forces. In the system, the calculation of the ultimate bearing capacity depends on the creep-consolidation coupling model and nonlinear constitutive relationship constructed by the foundation dynamic coupling calculation part in the previous stage. The model comprehensively considers the long-term creep effect of the foundation material, the consolidation effect of the pore water pressure, and the complex nonlinear mechanical behavior inside the foundation, so that it can accurately describe the overall response of the foundation under dynamic loads. By combining the variable diameter characteristics, that is, the law of the foundation stiffness changing with the radial direction, the system can effectively determine the ultimate bearing capacity of the foundation in different spatial regions. This process makes the bearing capacity calculation not only highly accurate, but also fully reflects the spatial heterogeneity and complexity of the foundation. On the basis of solving the ultimate bearing capacity, the bearing capacity calculation part further considers the influence of temperature effects. Temperature changes have a significant impact on the physical and mechanical properties of foundation materials, such as material expansion, contraction, and stiffness changes. The real-time monitoring data of the distributed optical fiber sensor array in the foundation provides accurate temperature change information. These data are transmitted to the bearing capacity calculation part and integrated into the calculation of the ultimate bearing capacity through the corresponding correction model. The temperature effect correction model fully considers the differences in different geological conditions and soil layer characteristics, and can dynamically adjust the calculation results under different environmental conditions of the system operation, so as to ensure that the final calculated bearing capacity data has high applicability and reliability. In addition to the temperature effect, the bearing capacity calculation part also introduces the foundation stability coefficient as a key parameter to evaluate the overall safety and stability of the foundation. The stability coefficient reflects the degree of proximity between the stress distribution of the foundation under the actual load and the limit state by combining the results of the dynamic coupling model and the variable diameter characteristics. The introduction of this parameter enables the system to not only evaluate the current bearing capacity of the foundation, but also to quantitatively analyze its safety, providing a clear decision-making basis for the construction site. The calculation of the stability coefficient fully considers the complexity of the foundation soil layer, the nonlinearity of mechanical behavior and the diversity of external loads, and has extremely high engineering practical significance. In the calculation of the current bearing capacity, the system combines the ultimate bearing capacity, temperature effect correction and stability coefficient, further integrates the dynamic strain characteristics and nonlinear constitutive relations, and realizes accurate bearing capacity evaluation. Specifically, the system uses an adaptive variable diameter recognition algorithm to dynamically adjust the calculation parameters during the extraction of variable diameter features, so that the final bearing capacity results can reflect the actual working conditions of the foundation in real time. This real-time performance is particularly important for rapid decision-making in complex engineering environments, and can significantly improve engineering safety and construction efficiency.

[0048] Embodiment 2: The fiber optic sensor is a fiber Bragg grating sensor or an optical time domain reflectometer; the geological data includes: soil damping ratio, soil elastic modulus, soil density, thickness of foundation soil layer, soil porosity ratio, soil permeability, unit weight of water, soil internal friction angle, soil viscosity coefficient, soil cohesion, and soil temperature.

[0049] Specifically, the fiber optic sensor includes a fiber Bragg grating sensor (Fiber Bragg Grating, FBG) and an optical time domain reflectometer (Optical Time Domain Reflectometer, OTDR). The fiber Bragg grating sensor is a sensor that uses periodic refractive index modulation in the optical fiber to reflect specific wavelength optical signals. When the optical fiber is subjected to strain or temperature changes, the reflected Bragg wavelength will change. By detecting these wavelength shifts, local strain and temperature changes can be accurately measured. The FBG sensor has the advantages of high sensitivity, strong anti-electromagnetic interference ability, small size and easy integration, and is very suitable for high-precision strain and temperature monitoring in complex foundation environments. On the other hand, the optical time domain reflectometer (OTDR) realizes continuous monitoring of the entire length of the optical fiber by sending short pulse optical signals into the optical fiber and detecting the return time and intensity of the scattered optical signals (such as Rayleigh scattering, Brillouin scattering, and Raman scattering). The OTDR can provide high-resolution strain and temperature distribution information along the length of the optical fiber and is suitable for large-scale and multi-point foundation strain monitoring. The combination of these two sensors not only ensures high-precision local strain measurement but also realizes large-scale distributed monitoring, greatly improving the data acquisition ability and monitoring coverage of the system.

[0050] In terms of geological data, this embodiment details a number of key parameters, including soil damping ratio, soil elastic modulus, soil density, thickness of foundation soil layer, soil porosity ratio, soil permeability, unit weight of water, soil internal friction angle, soil viscosity coefficient, soil cohesion, and soil temperature. These parameters comprehensively reflect the physical and mechanical properties of the foundation soil and are the basic data for constructing the foundation dynamic coupling model and carrying out bearing capacity calculation. The soil damping ratio and soil viscosity coefficient describe the energy dissipation characteristics of the soil under vibration loads and directly affect the dynamic response and stiffness characteristics of the foundation. The soil elastic modulus and soil density determine the elastic deformation ability and inertial characteristics of the foundation under external loads. The thickness of the foundation soil layer and the soil porosity ratio reflect the hierarchical structure of the foundation and the pore water pressure distribution, and are important parameters for evaluating the consolidation effect and creep behavior. The soil permeability and the unit weight of water affect the hydrodynamic response of the foundation and the change of pore water pressure, and have a significant impact on the long-term stability of the foundation. The soil internal friction angle and soil cohesion are important indicators for measuring the shear strength of the soil and are directly related to the ultimate bearing capacity and stability of the foundation.

[0051] Example 3: Three-dimensional strain field distribution Use the following formula to express it:

[0052] ;

[0053] in, is the soil damping ratio; is the soil density; is the elastic modulus of soil; is an integer subscript index; is an integer subscript index; is the number of fiber optic sensors in the row direction of the distributed fiber optic sensing array; is the number of optical fiber sensors in the column direction of the distributed optical fiber sensing array; The first distributed optical fiber sensor array Row, No. The displacement measured by the optical fiber sensors in the series; Represents the second-order partial derivative of the displacement in the X-axis direction and the Y-axis direction; Represents the second-order partial derivative of the displacement in the X-axis direction and the Z-axis direction; Represents the second-order partial derivative of the displacement in the Y-axis direction and the Z-axis direction; represents the distance of the sensor array from the foundation surface; is the shear wave propagation velocity in soil; is the frequency of the light wave of the fiber optic sensor.

[0054] Specifically, the formula Represents the three-dimensional strain field distribution, and its solution is based on the measurement data of the distributed fiber optic sensor array. The core function of the fiber optic sensor is to measure the tiny displacement of the foundation under the external load, and extract the coupling change characteristics of the displacement in different directions by performing partial derivative calculations on these displacement data. The formula contains three high-order partial derivatives: , and , these terms represent the second-order partial derivatives of displacement in three different coordinate directions, capturing the coupled strains generated by mechanical interactions in the foundation in space. The use of this high-order partial derivative shows that the strain in the foundation is not only a response in a single direction, but the result of the combined effect of strains in multiple directions. Through the mathematical description of these coupled strains, the system can deeply reflect the complex force distribution law inside the foundation. is a key combination of physical parameters, among which represents the elastic modulus of the soil, is the density of the soil. This ratio physically corresponds to the inherent property of wave propagation in the soil, namely the wave propagation velocity of the soil. It reflects the ability of soil to resist deformation, while density Determines the inertia effect of the soil. The combination of the two explains the response rate and strength of the soil when subjected to dynamic loads. In this formula, this parameter determines the propagation speed of the strain field in space and the overall response efficiency, reflecting the physical meaning of the dynamic characteristics of the soil. The exponential decay term in the second half of the formula It is used to describe the energy attenuation effect caused by soil damping during wave propagation. is the soil damping ratio, which indicates the ability of the soil to dissipate energy during vibration. is the frequency of the light wave, is the shear wave propagation velocity in the soil, and is the distance between the sensor array and the foundation surface. The form of the exponential term indicates that as the propagation distance of the wave increases, the energy attenuation caused by damping and medium absorption effects decreases exponentially. The design of this part physically reflects the inelastic behavior of the medium during the wave propagation process. By incorporating the attenuation effect into the calculation of the strain field, the system can more realistically reflect the behavior of the foundation under dynamic loads. The overall principle of this formula also involves the integration of the measurement data of each sensor in the fiber optic sensor array. The sensor array consists of Line and The data of each sensor is represented by its displacement As the basic input, by traversing the entire array (i.e. and The formula can integrate the response of local displacement into a global three-dimensional strain field. The principle of this global integration method is to derive the continuous strain field distribution through the calculation of discrete sampling points, so as to achieve the modeling of the overall deformation state of the foundation. This method makes up for the shortcomings of traditional monitoring technology in spatial coverage and accuracy, enabling the system to fully capture the complex forces and deformations inside the foundation.

[0055] Example 4: Foundation dynamic stiffness matrix The formula is as follows:

[0056] ;

[0057] in, express The second-order partial derivative in the X-axis direction; express The second-order partial derivative in the Y-axis direction; express The second-order partial derivative in the Z-axis direction; express Second-order partial derivatives in the X-axis and Y-axis directions; express Second-order partial derivatives in the X-axis and Z-axis directions; express Second-order partial derivatives in the Y-axis and X-axis directions; express Second-order partial derivatives in the Y-axis and Z-axis directions; express Second-order partial derivatives in the Z-axis and X-axis directions; express Second-order partial derivatives in the Z-axis and Y-axis directions; Indicates the thickness of the foundation soil layer; is the boundary surface of the strain field, defined as the boundary surface of the distributed optical fiber sensor array.

[0058] Specifically, the starting point of the formula is the expression of the three-dimensional strain gradient, that is, each term in the matrix represents the rate of change of the three-dimensional strain component in a certain direction in space. These terms reveal the gradient change of strain in different directions in the foundation with position, reflecting the mechanical response characteristics of the material in the local area. Diagonal elements such as , , It directly reflects the change of strain in a single direction, which is the basic source of foundation stiffness. , It represents the coupling effect between different directions, revealing the complex coupled deformation of the foundation under multi-axial load. The comprehensive expression of strain gradients in all directions in three-dimensional space enables the formula to not only capture the characteristics of isotropic foundations, but also reflect the dynamic stiffness characteristics of anisotropic or inhomogeneous foundations. The introduction of the integral operation in the formula is to integrate the contribution of local strain gradients into the entire monitoring range, that is, in the region The strain gradient distribution is accumulated over the entire domain. The physical significance of this integration is to unify the local strain changes of each sensor point measured by the distributed fiber optic sensor array to form a comprehensive description of the global stiffness of the foundation. The integration operation ensures that the foundation dynamic stiffness matrix not only reflects the local mechanical properties, but also reveals the dynamic behavior of the foundation as a whole. This global integration method is particularly important under complex foundation conditions, such as when there are multiple layers of soil or significant spatial inhomogeneity. The exponential decay term The introduction of further enhances the physical reality of the formula and reflects the influence of soil depth on stiffness. and elastic modulus The relationship shows that with the increase of depth, the stiffness of the foundation will increase due to the increase of soil density and the decrease of porosity. However, due to the attenuation effect of material properties and the decreasing characteristics of the transmission of external force influence, the increase of stiffness is not linear, but gradually slows down. This exponential form can well fit the law of stiffness change in the actual foundation, thereby improving the accuracy of the model. In addition, the attenuation term also takes into account the energy dissipation effect of the material during dynamic loading, which is particularly critical when describing the behavior of the foundation under dynamic loads. Foundation dynamic stiffness matrix The core of the construction lies in the combination of strain gradient and depth correlation. The strain gradient reflects the local response characteristics of the foundation material, while the depth correlation incorporates the influence of spatial distribution into the model. This multi-factor coupling makes It becomes a highly comprehensive stiffness description tool that can reflect both local nonlinear effects and overall macroscopic characteristics. Through this matrix, not only can the dynamic mechanical behavior of the foundation at a specific location and condition be characterized, but also high-quality input data can be provided for the bearing capacity calculation of the system.

[0059] Example 5: Using the following formula, the variable diameter feature is extracted from the foundation dynamic stiffness matrix through Fourier-Laplace transform:

[0060] ;

[0061] in, Representation calculation The determinant of ; represents Fourier transform; is the Laplace transform complex variable; is the specific gravity of water; is the soil permeability; is the position integral variable of the X-axis; is the position integral variable of the Y axis; is the Z-axis position integral variable.

[0062] Specifically, the foundation dynamic stiffness matrix The determinant of It is a global measure of the mechanical properties of the foundation. The determinant is essentially a compressed representation of the stiffness matrix, which comprehensively reflects the degree of coupling of the stiffness in each direction in the matrix and the overall response strength. The absolute value of the determinant It is used as the input of Fourier transform to transform the spatial distribution characteristics of stiffness from time domain to frequency domain in order to analyze the response characteristics of the foundation in different frequency ranges. The core principle of the Fourier transform is to express the change of foundation stiffness as the superposition of frequency components. This frequency domain analysis can reveal the vibration mode and stiffness change trend of the foundation under dynamic load. The result of Fourier transform is combined with the exponential decay term in Laplace transform. , which is used to describe the dynamic attenuation characteristics of foundation stiffness with depth and time. The introduction of this attenuation term is based on the physical energy dissipation mechanism: when the dynamic load acts on the foundation, the wave propagates in the medium and gradually attenuates due to the viscosity and permeability of the soil. In the formula, the soil permeability , water density And depth The coupling effect of the dissipation process reflects the influence of the stiffness change. This indicates the velocity of wave propagation in the soil, reflecting the dynamic characteristics of the material. It captures the time decay behavior of dynamic systems and mathematically accurately represents complex time changes with an exponential function.

[0063] Global integration operation The principle is to integrate the local dynamic stiffness characteristics into the entire foundation range, thereby generating a global variable diameter characteristic quantity. . Integration variable , , They represent the three-dimensional spatial coordinates of the foundation respectively. By integrating and accumulating the dynamic stiffness contributions within the measurement range of all sensors, the formula is able to capture the spatial variation of stiffness in the entire foundation area. This global integration operation not only takes into account the local characteristics of each point, but also reveals the variable diameter trend of stiffness through the comprehensive effect within the spatial range, that is, the regularity of the change of foundation stiffness with radial distance. The Fourier transform processes the frequency characteristics to help the system identify the performance of stiffness under different frequency components of dynamic loads, while the Laplace transform captures the attenuation behavior of stiffness in the time domain. After combining the two, the formula can not only describe the distribution law of foundation stiffness in space, but also explain its dynamic characteristics evolving over time. This dual perspective enables the formula to adapt to complex foundation conditions, such as multi-layer soil, saturated soil, or foundations with significant dissipative characteristics, thereby improving the system's adaptability to practical engineering problems. From a physical point of view, the variable diameter characteristics It is a quantitative description of the change of foundation stiffness in the radial direction. The change of radial stiffness directly reflects the non-uniform response characteristics of the foundation to the load, and is a key factor affecting the stability and bearing capacity distribution of the foundation. Through the Fourier-Laplace transform in the formula, the system can accurately extract these characteristics and provide high-quality input data for subsequent ultimate bearing capacity calculations and stability assessments. In addition, the formula can dynamically adjust the calculation results through direct association with foundation material parameters (such as permeability, wave velocity, etc.), reflecting the ability to adapt to different geological conditions.

[0064] Example 6: The foundation creep-consolidation coupling model is calculated using the following formula:

[0065] ;

[0066] in, is the characteristic consolidation time, which is obtained by the following process: in the field loading test, the pore water pressure of the soil after loading is recorded as a function of time. The time of t is regarded as the characteristic consolidation time ; is the soil porosity ratio; is the drainage path length, i.e. the maximum distance of drainage of the foundation soil layer. For unidirectional drainage, it is the thickness of the foundation soil layer, and for bidirectional drainage, it is half of the thickness of the foundation soil layer; It is the interval between the current measurement time and the last measurement time of all sensors in the distributed optical fiber sensor array.

[0067] Specifically, in the formula, It is the effective stress of the foundation, which is used to measure the actual stress state between soil particles and is a key parameter that determines the stability and bearing capacity of the foundation. describes the change in effective stress in the foundation due to the pore water pressure gradient. Here, is the strain with depth The rate of change of reflects the deformation gradient of the soil along the drainage path. The dissipation of pore water pressure is affected by the soil permeability (permeability ) and the bulk density of water control, This term describes the ability of pore water to flow in the soil. By applying a gradient to the pressure change in the depth direction, the formula captures the dynamic relationship between the dissipation of pore water pressure and the recovery of effective stress, which is the core of the consolidation effect. The second term of the formula is It describes the creep effect of the foundation and its coupling behavior with the consolidation effect. First, Based on the soil porosity Modified elastic modulus , which is used to describe the magnitude of the restoring force of the soil during creep. The void ratio reflects the void characteristics between particles inside the soil. A larger void ratio usually corresponds to lower stiffness and higher creep rate. is the attenuation function of the time factor, reflecting the nonlinear weakening characteristics of the consolidation process over time. When it increases, the consolidation and creep effects gradually tend to be stable, and the exponential term decreases, indicating that the deformation of the soil under long-term loading tends to be stable. It is an important parameter obtained through field loading tests, indicating the time it takes for the pore water pressure to dissipate by 90%. This parameter directly affects the formula's description of the time decay law and is the key to the model's dynamics.

[0068] Geometric parameters in formulas (Drainage path length) further reflects the influence of soil drainage characteristics on consolidation and creep by defining the maximum distance of drainage. The difference between unidirectional drainage and bidirectional drainage makes It can adapt to different foundation structure conditions, thus enhancing the practical applicability of the model. It reflects the depth of the wave propagation process. The influence on stress transfer, combined with , describes the modulation effect of soil permeability on the creep-consolidation coupling effect. In principle, creep and consolidation are the two core deformation mechanisms of foundations under long-term loading. Consolidation is a process in which the force between soil particles increases due to the dissipation of pore water pressure, thereby causing volume compression, and its time scale is determined by the permeability characteristics and drainage conditions of the soil. Creep is the phenomenon that the soil gradually deforms due to viscosity under constant effective stress, which is mainly controlled by the elastic modulus and time effect of the soil. This formula captures the dynamic nature of the mechanical behavior of the soil by coupling the two effects together. Compared with the traditional method of modeling consolidation or creep separately, the formula in Example 6 significantly expands the scope of application and accuracy of the model. Traditional methods usually assume that creep and consolidation are independent of each other and cannot accurately describe their coupled behavior of mutual influence in actual engineering. This formula comprehensively captures the dynamic change characteristics of the soil creep-consolidation process by introducing time attenuation terms and geometric correction terms in the calculation of effective stress. This coupled modeling method enables the model to better adapt to complex foundation conditions, such as soil environments with high porosity, low permeability or complex drainage paths. From the perspective of engineering applications, this formula provides important theoretical support for the dynamic evaluation of foundation bearing capacity. The creep-consolidation coupling model can predict the deformation and stability of soil under long-term loading in real time, providing a scientific basis for optimizing construction plans, evaluating the long-term bearing capacity of the foundation, and preventing foundation instability. At the same time, through parameters (such as , , The model has strong adaptive capability and can be flexibly adjusted to meet different geological conditions and construction requirements.

[0069] Example 7: The nonlinear constitutive relationship is expressed by the following formula:

[0070] ;

[0071] in, is the maximum shear stress; is the time-integrated variable; is the soil viscosity coefficient; is the friction angle within the soil; is the soil cohesion; is the soil temperature.

[0072] Specifically, the first part of the formula is an extension of the classical Mohr-Coulomb failure criterion, where is the cohesion of the soil, is the internal friction angle of soil, is the effective normal stress. Describes the cohesion between soil particles, the magnitude of which is affected by the soil structure and composition; internal friction angle It reflects the friction characteristics between particles and is closely related to the density and particle shape of the soil. Indicates the actual bearing capacity between soil particles, which is affected by the pore water pressure. In static conditions, this part directly determines the shear strength of the soil. The dynamic part of the formula Time correlation and nonlinear characteristics are further introduced. First, the viscosity coefficient in the integral term It is a parameter that describes the viscous deformation of soil under stress and reflects the time dependence of soil. A larger viscosity coefficient means that the soil will produce more significant time-dependent deformation (i.e. creep effect) under long-term loading. The exponential decay term in the time integral describes the gradual decay of the shear stress response over time, where is the characteristic consolidation time, which indicates the time it takes for 90% of the pore water pressure in the soil to dissipate. This index term indicates that the dynamic shear response of the soil is most significant at the beginning of loading and gradually stabilizes over time, reflecting the law of stress relaxation in the dynamic creep process.

[0073] The dynamic part also incorporates the three-dimensional displacement gradient of the soil through high-order partial derivatives , and The product of captures the coupled deformation behavior of the foundation under multiaxial stress conditions. These high-order partial derivatives mathematically describe the complex shear deformation pattern of the foundation in space, and reflect the sum of the deformation intensity through absolute value operation. Combining the viscosity coefficient and temperature parameters The dynamic part quantifies the nonlinear shear response of the soil under complex loading conditions. The temperature effect is measured by the parameter The introduction of the formula reflects the effect of ambient temperature on the viscosity and strength of the soil. Higher temperatures usually reduce the viscosity and internal friction angle of the soil, thereby affecting the shear resistance of the soil. The formula further enhances the adaptability of the constitutive model to environmental conditions by adjusting the temperature of the dynamic part. Compared with the traditional Mohr-Coulomb model, this formula introduces the dynamic coupling of time, temperature and higher-order deformation. Traditional models usually assume that the shear response of the soil is instantaneous and ignore the complexity of time correlation and dynamic loading. This formula fully captures the complex behavior of the soil under long-term loading through time integration and nonlinear dynamic response, so that the model can more accurately describe the shear failure characteristics of the soil under complex conditions. From a physical point of view, the dynamic part of the formula can be understood as the cumulative effect of the dynamic response of the soil at different time points. By superimposing the shear deformation contribution at each moment, the formula reveals the total shear response of the soil under long-term stress conditions. This method not only considers the instantaneous strength of the soil, but also quantifies the effects of stress distribution and deformation accumulation during long-term loading.

[0074] Example 8: The ultimate bearing capacity is calculated by combining the variable diameter characteristics and the nonlinear constitutive relationship through the following formula:

[0075] ;

[0076] in, is the foundation pile length; is the ultimate bearing capacity.

[0077] Specifically, in the formula, the ultimate bearing capacity By the foundation pile length and foundation range Double integration is performed to obtain, which reflects the distribution of bearing capacity of the foundation in the entire spatial range. The core of the formula consists of three parts: maximum shear stress , index item and stiffness correction They describe the contribution of the shear strength, compression characteristics and stiffness change of the foundation material to the bearing capacity. , is the maximum shear stress extracted from the nonlinear constitutive relationship, representing the ability of the soil to resist shear failure under the limit state. It combines the cohesion, internal friction angle, effective stress and time-dependent response of the soil under dynamic loading conditions. In the foundation bearing capacity calculation, It is an important parameter that directly reflects the shear strength of the foundation, and its size is significantly affected by the properties of the foundation material and the current stress state. Used to describe the impact of the compression effect of the foundation on the bearing capacity. is the elastic modulus of the soil, is the initial void ratio of the soil. This term physically reflects the change in stiffness of the soil during compression. A higher elastic modulus and a lower void ratio will increase the compressive strength of the soil, thereby increasing the bearing capacity; while the exponential form indicates that the contribution of the compression effect to the bearing capacity is nonlinearly attenuated.

[0078] Stiffness correction The variable diameter feature is introduced and effective stress , which is used to describe the modulation effect of the spatial distribution of foundation stiffness on the bearing capacity. It is extracted from the foundation dynamic stiffness matrix through Fourier-Laplace transform and represents the regularity of the foundation stiffness changing with the radial direction. is the actual stress state between foundation particles, which directly affects the stability and deformation resistance of the soil. and The formula can capture the dynamic effect of the change in foundation stiffness on bearing capacity under radial non-uniform conditions. The core of this item is to reflect the spatial response characteristics of the foundation under complex stress conditions. and The double integration of realizes the comprehensive integration of the mechanical behavior of the entire foundation pile length and spatial range. Used to calculate the depth of the foundation Total bearing capacity on the cross section, summing up the shear strength and stiffness distribution in two dimensions; external integral The contribution within the entire pile length is accumulated to obtain the total bearing capacity of the foundation at all depths. Compared with the traditional bearing capacity calculation method, this formula takes into account the coupling of static and dynamic factors at the same time. Traditional methods are usually based on simplified static mechanical models, ignoring the spatial variation and time-related effects of foundation stiffness. This formula, by combining variable diameter characteristics, nonlinear constitutive relations and dynamic responses, can not only reflect the bearing characteristics of the foundation under complex working conditions, but also significantly improve the accuracy and applicability of bearing capacity assessment. From a physical point of view, the core of the formula is to reveal the multi-factor coupling mechanism of foundation bearing capacity. Maximum shear stress Reflects the local shear strength of the soil; the exponential term It reflects the change of stiffness of foundation material under compression; stiffness correction term The dynamic variation of foundation stiffness with spatial distribution is revealed through variable diameter characteristics and effective stress. This multi-factor comprehensive modeling method enables the formula to not only capture the physical properties of the foundation material itself, but also reflect the dynamic impact of external loads and environmental conditions on bearing capacity.

[0079] Example 9: The foundation stability coefficient is calculated by the following formula based on the ultimate bearing capacity and considering the temperature effect: :

[0080] ;

[0081] in, is the gas constant; is the average ground temperature.

[0082] Specifically, the first part of the formula The ultimate bearing capacity and comprehensive quantification of three-dimensional displacement gradients. is the maximum bearing capacity of the foundation under extreme conditions, calculated by the double integral method in the above embodiment. The square root term in the denominator contains the high-order gradient of the three-dimensional displacement , , , these gradient terms reflect the coupled deformation behavior of the foundation in different directions. The product of these high-order partial derivatives represents the intensity of shear deformation in all directions in space, and the square root of its absolute value reflects the comprehensive degree of complex mechanical response inside the foundation. Combined with these gradient characteristics, the formula can dynamically reflect the ratio of the ultimate bearing capacity of the foundation to the local deformation intensity, thus measuring the overall stability of the foundation. is an exponential correction term for the ground wave propagation characteristics, where is the fluctuation frequency, is the wave propagation speed in the soil, is the elastic modulus of the soil. This term reflects the influence of soil stiffness on stability during wave propagation. and propagation speed The exponential decay amplitude is reduced, indicating that the foundation can transfer stress more effectively and has higher stability. This exponential term also reveals the influence of energy loss caused by wave propagation on the stability of the foundation under dynamic loading.

[0083] Part 3 is a quantitative description of the influence of temperature effect on foundation stability. Here, is the gas constant, is the soil temperature, is the average temperature of the foundation. It reflects the degree of deviation of the current soil temperature from the average temperature, and the weight of the temperature effect is calculated by the gas constant When the soil temperature Significantly higher than average temperature hour, The value of the term is small, indicating that the influence of temperature effect on stability is weakened. This part of the formula reflects the dynamic regulation ability of soil temperature on its mechanical properties (such as internal friction angle, cohesion, etc.): higher temperature may reduce the viscosity and shear strength of the soil, thereby affecting the overall stability of the foundation. The structure of the formula combines static mechanical properties, dynamic wave propagation characteristics and thermodynamic effects, reflecting the multi-dimensionality of foundation stability assessment. Compared with the traditional stability calculation method, the formula combines the ultimate bearing capacity, shear deformation strength and temperature effect, not only considering the static bearing capacity of the foundation, but also introducing the influence of dynamic environment and temperature changes. Traditional methods usually ignore the dynamic response and thermal effect of the foundation under complex environmental conditions, while this formula achieves a more comprehensive description of foundation stability through the coupling of three parts. From a physical point of view, the first part of the formula measures the ratio of the ultimate bearing capacity of the foundation to its local shear deformation strength, reflecting the influence of the spatial distribution of mechanical properties on stability; the second part reveals the modulation effect of dynamic stress distribution on stability through wave propagation characteristics; the third part describes the dynamic adjustment of environmental factors to the overall performance of the foundation through temperature effects. This multi-factor coupling calculation method enables the formula to not only accurately evaluate the foundation stability under complex working conditions, but also dynamically respond to changes in environmental and load conditions.

[0084] Example 10: The current bearing capacity is calculated by the following formula based on the stability coefficient, combined with the variable diameter characteristics and the nonlinear constitutive relationship: :

[0085] ;

[0086] in, is the set standard variable diameter characteristic value; is the set standard elastic modulus.

[0087] Specifically, the first part of the formula It reflects the dynamic characteristics of bearing capacity changing with time. Here, It is the ultimate bearing capacity of the foundation, which represents the maximum load that the foundation can withstand under the limit state. The growth process of the current carrying capacity is described in exponential form, where is the characteristic consolidation time, which indicates the time required for 90% of the pore water pressure in the soil to dissipate. ), the time correction term is close to zero, indicating that the bearing capacity of the foundation has not been fully exerted; as time increases (i.e. ), the correction term tends to 1, indicating that the foundation is gradually approaching its ultimate bearing capacity. This part reveals the law that the foundation bearing capacity gradually increases over time, reflecting the dynamic process of consolidation and stress transfer. Part II Indicates the regulatory effect of stability and elastic modulus on bearing capacity. Stability coefficient It is calculated based on the stability of the foundation and is an important indicator of foundation safety. Used to correct the elastic properties and standard elastic modulus of the current soil Higher elastic modulus It means that the soil has a greater ability to resist deformation under stress, thus improving the current bearing capacity; and by comparing with the standard elastic modulus The formula can adapt to the soil characteristics under different geological conditions, reflecting the wide adaptability of the model. It is the spatial integral of the variable diameter feature. It is extracted from the dynamic stiffness matrix by Fourier-Laplace transform and is used to describe the spatial distribution of foundation stiffness; is the standard variable diameter feature value set, which is used to normalize the current stiffness change. , the formula can dynamically adjust the sensitivity of the bearing capacity to the change of radial stiffness, while ensuring an accurate description of the spatial heterogeneity of the foundation. Used to express the stiffness as a function of depth The attenuation characteristics, where It is a depth-dependent adjustment parameter, reflecting the decreasing law of soil stiffness at different depths. The stiffness contribution within the entire foundation pile length is integrated into the overall characteristic, reflecting the global influence of pile length on bearing capacity. Traditional bearing capacity calculations are usually based on static or simplified mechanical models, ignoring the dynamic changes and spatial heterogeneity of the foundation under complex stress conditions. This formula organically combines static characteristics with dynamic characteristics, local response with global behavior through multiple correction terms and integral operations, significantly improving the accuracy and adaptability of bearing capacity prediction. From a physical point of view, each part of the formula reveals the key influencing mechanism of foundation bearing capacity: the time correction term describes the time evolution law of bearing capacity, reflecting the dynamic process of consolidation effect and stress transfer; the stability coefficient and elastic modulus ratio reflect the safety state and deformation resistance of foundation materials; the variable diameter characteristic integral reveals the change law of foundation stiffness with depth and spatial distribution, as well as its global influence on bearing capacity. This multi-factor coupling modeling method enables the formula to not only adapt to different geological conditions and working conditions, but also accurately predict the change trend of current foundation bearing capacity.

[0088] Although the specific embodiments of the present invention are described above, it should be understood by those skilled in the art that these specific embodiments are only illustrative, and those skilled in the art may omit, replace, and change the details of the above methods and systems in various ways without departing from the principles and essence of the present invention. For example, merging the above method steps so as to perform substantially the same functions in substantially the same manner to achieve substantially the same results is within the scope of the present invention. Therefore, the scope of the present invention is limited only by the appended claims.

Claims

1. A rapid detection system for composite foundation bearing capacity based on an adaptive variable diameter identification algorithm, characterized in that: The system comprises: a distributed optical fiber sensing array, a foundation strain feature extraction part, a foundation dynamic coupling calculation part and a bearing capacity calculation part; the distributed optical fiber sensing array comprises a plurality of optical fiber sensors arranged in an array and arranged on the foundation, each optical fiber sensor collects foundation strain data and constructs a three-dimensional strain field distribution; the foundation strain feature extraction part is used to construct a foundation dynamic stiffness matrix based on the three-dimensional strain field distribution; the variable diameter feature is extracted from the foundation dynamic stiffness matrix by Fourier-Laplace transform; the foundation dynamic coupling calculation part is used to establish a foundation creep-consolidation coupling model according to the three-dimensional strain field distribution and the geological data of the foundation, and to construct a nonlinear constitutive relationship based on the creep-consolidation coupling model; the ultimate bearing capacity is calculated by combining the variable diameter feature and the nonlinear constitutive relationship; the bearing capacity calculation part is used to calculate the foundation stability coefficient according to the ultimate bearing capacity and considering the temperature effect, and calculate the current bearing capacity according to the stability coefficient and in combination with the variable diameter feature and the nonlinear constitutive relationship; Three-dimensional strain field distribution Use the following formula to express it: ； in, is the soil damping ratio; is the soil density; is the elastic modulus of soil; is an integer subscript index; is an integer subscript index; is the number of fiber optic sensors in the row direction of the distributed fiber optic sensing array; is the number of optical fiber sensors in the column direction of the distributed optical fiber sensing array; The first distributed optical fiber sensor array Row, No. The displacement measured by the optical fiber sensors in the series; Represents the second-order partial derivative of the displacement in the X-axis direction and the Y-axis direction; Represents the second-order partial derivative of the displacement in the X-axis direction and the Z-axis direction; Represents the second-order partial derivative of the displacement in the Y-axis direction and the Z-axis direction; represents the distance of the sensor array from the foundation surface; is the shear wave propagation velocity in soil; is the frequency of the optical wave of the fiber optic sensor.

2. The composite foundation bearing capacity rapid detection system based on the adaptive variable diameter identification algorithm according to claim 1 is characterized in that: The optical fiber sensor is a fiber Bragg grating sensor or an optical time domain reflectometry sensor; the geological data include: soil damping ratio, soil elastic modulus, soil density, foundation soil layer thickness, soil porosity, soil permeability, water bulk density, soil internal friction angle, soil viscosity coefficient, soil cohesion and soil temperature.

3. The composite foundation bearing capacity rapid detection system based on the adaptive variable diameter identification algorithm according to claim 1 is characterized in that: Dynamic stiffness matrix of foundation The formula is as follows: ； in, express The second-order partial derivative in the X-axis direction; express The second-order partial derivative in the Y-axis direction; express The second-order partial derivative in the Z-axis direction; express Second-order partial derivatives in the X-axis and Y-axis directions; express Second-order partial derivatives in the X-axis and Z-axis directions; express Second-order partial derivatives in the Y-axis and X-axis directions; express Second-order partial derivatives in the Y-axis and Z-axis directions; express Second-order partial derivatives in the Z-axis and X-axis directions; express Second-order partial derivatives in the Z-axis and Y-axis directions; Indicates the thickness of the foundation soil layer; is the boundary surface of the strain field, which is defined as the boundary surface of the distributed optical fiber sensor array.

4. The composite foundation bearing capacity rapid detection system based on the adaptive variable diameter identification algorithm as claimed in claim 3 is characterized in that: The variable diameter feature is extracted from the foundation dynamic stiffness matrix by Fourier-Laplace transform using the following formula: ； in, Representation calculation The determinant of ; represents Fourier transform; is the Laplace transform complex variable; is the bulk density of water; is the soil permeability; is the position integral variable of the X-axis; is the position integral variable of the Y axis; is the Z-axis position integral variable.

5. The composite foundation bearing capacity rapid detection system based on the adaptive variable diameter identification algorithm according to claim 4 is characterized in that: The foundation creep-consolidation coupling model is calculated using the following formula: ； in, is the characteristic consolidation time, which is obtained by the following process: in the field loading test, the pore water pressure of the soil after loading is recorded as a function of time. The time of t is regarded as the characteristic consolidation time ; is the soil porosity ratio; is the drainage path length, i.e. the maximum distance of drainage of the foundation soil layer. For unidirectional drainage, it is the thickness of the foundation soil layer, and for bidirectional drainage, it is half of the thickness of the foundation soil layer; It is the interval between the current measurement time and the last measurement time of all sensors in the distributed optical fiber sensor array.

6. The composite foundation bearing capacity rapid detection system based on the adaptive variable diameter identification algorithm according to claim 5 is characterized in that: The nonlinear constitutive relation is expressed by the following formula: ； in, is the maximum shear stress; is the time-integrated variable; is the soil viscosity coefficient; is the friction angle within the soil; is the soil cohesion; is the soil temperature.

7. The composite foundation bearing capacity rapid detection system based on the adaptive variable diameter identification algorithm according to claim 6 is characterized in that: The ultimate bearing capacity is calculated by combining the variable diameter characteristics and the nonlinear constitutive relationship through the following formula: ； in, is the foundation pile length; is the ultimate bearing capacity.

8. The composite foundation bearing capacity rapid detection system based on the adaptive variable diameter identification algorithm according to claim 7 is characterized in that: The foundation stability coefficient is calculated based on the ultimate bearing capacity and considering the temperature effect through the following formula: : ； in, is the gas constant; is the average ground temperature.

9. The composite foundation bearing capacity rapid detection system based on the adaptive variable diameter identification algorithm according to claim 8 is characterized in that: The current bearing capacity is calculated by the following formula based on the stability coefficient, combined with the variable diameter characteristics and nonlinear constitutive relationship. : ； in, is the set standard variable diameter characteristic value; is the set standard elastic modulus.

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