Inversion method of pile foundation construction and geological exploration technology

Abstract

The invention belongs to the technical field of pile foundation construction, and particularly relates to an inversion method of a pile foundation construction and geological exploration technology, which comprises the following steps of: 1, collecting geological exploration data; the method comprises the following steps: acquiring property data of an underground soil layer through drilling and in-situ testing operation, including the thickness, compactness and soil type of the soil layer; and calculating the numerical values of the thickness, the compactness and the soil type of the soil layer through a static sounding test method. According to the inversion method of the pile foundation construction and geological exploration technology, accurate geological exploration data can be provided, specific characteristics of an underground soil layer are calculated through the inversion method, and accurate parameters are provided for pile foundation design. Meanwhile, the interaction between the pile foundation and the soil layer is simulated through a finite element method, deformation and stress distribution in the construction process are predicted, and a scientific basis is provided for engineering design. In addition, settlement and pile sinking resistance of the pile foundation need to be monitored in real time, so that a construction scheme is adjusted in time, and construction safety and quality are ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of pile foundation construction, and in particular to an inversion method of pile foundation construction and geological detection technology. Background Art

[0002] In the field of pile foundation construction and geological exploration, traditional construction methods often rely on empirical judgment and simplified models, which leads to a series of problems. First, the limitations of geological exploration data: Traditional geological exploration methods, such as drilling and sampling, can only provide limited and local geological information, and it is difficult to fully reflect the complexity and variability of the underground soil. This affects the accuracy and reliability of geological exploration results. Second, the conservatism of pile foundation design: Due to the lack of accurate geological data, pile foundation design often relies on empirical judgment and simplified models, resulting in overly conservative estimates of soil parameters. This can lead to uneconomical and unreasonable design results, increasing project costs. Finally, the inadequacy of construction monitoring: Existing construction monitoring methods are limited, making it difficult to obtain real-time information on the settlement and stress distribution of the pile foundation. This can lead to safety hazards during construction and increase project risks.

[0003] Therefore, an inversion method of pile foundation construction and geological exploration technology is needed. Summary of the Invention

[0004] Based on the existing technical problems, the present invention proposes an inversion method of pile foundation construction and geological exploration technology.

[0005] The present invention proposes an inversion method for pile foundation construction and geological exploration technology, comprising the following steps: Step 1: geological exploration data collection; obtaining underground soil property data, including soil thickness, density, and soil type, through drilling and in-situ testing operations; and calculating the soil thickness, density, and soil type values ​​through a static penetration test method;

[0006] Step 2: Monitoring of pile foundation construction, monitoring of pile settlement and pile sinking resistance;

[0007] Step 3: Inversion operation, by inverting the geological exploration data obtained in step 1 and the monitoring data of the pile foundation construction obtained in step 2, the specific characteristics of the underground soil layer are calculated;

[0008] Step 4: In order to obtain the optimal underground soil characteristics during the inversion process, different data sources are integrated;

[0009] Step 5: Analyze and judge the inversion data results.

[0010] Preferably, the static penetration test operation steps in step 1 are as follows: a1. Before the test, a hole is drilled at a designated location to determine the depth of the hole;

[0011] a2. Use a static cone penetration instrument to push the probe vertically into the underground soil layer. The probe is equipped with multiple sensors;

[0012] a3. The front end of the probe has a conical tip with a pressure sensor. As the probe penetrates into the soil, the pressure sensor records the penetration resistance and friction resistance of the soil.

[0013] Cone penetration resistance qc: The resistance generated when the measuring probe enters the soil layer. The formula is: Among them, F cone is the pressure recorded by the cone tip sensor, A cone is the contact area of ​​the cone tip;

[0014] Friction resistance fs: is the resistance caused by friction between the probe side and the soil layer. The formula is: Among them, F fric is the force recorded by the side friction sensor, A fric is the contact area of ​​lateral friction;

[0015] a4. The resistance data generated by different depths of the soil layer will be recorded in real time to form the mechanical response data of the soil layer; by analyzing the cone penetration resistance qc and friction resistance fs, the type and density of the soil layer will be evaluated; the ratio Among them, Rf < 0.5 indicates sandy soil or loose soil, and Rf > 1.0 indicates clay or high-clay soil.

[0016] Preferably, the settlement monitoring of the pile in step 2 mainly measures the vertical displacement of the pile top. The settlement of the pile is the deformation of the pile body after bearing the load. The settlement formula is: Where S is the settlement, P is the load on the pile top, A is the cross-sectional area of ​​the pile, L is the length of the pile, and E is the elastic modulus of the pile soil;

[0017] The pile sinking resistance in step 2 is calculated by measuring the resistance the pile encounters during the sinking process. The pile sinking resistance is related to the shear strength of the soil layer and is calculated using the formula: R = ∑(τ × A 面积 ), where τ is the shear strength of the soil layer, A 面积 is the contact area of ​​the soil layer.

[0018] Preferably, in the inversion operation step in step 3, the soil layers are first divided according to the data obtained in steps 1 and 2, and the physical parameters of each soil layer are determined, including density, moisture content and effective stress; and the mechanical parameters of the soil layer are then determined, including elastic modulus, Poisson's ratio, cohesion and friction angle;

[0019] Elastic modulus E 模量 Indicates the stiffness of the soil layer: E 模量 =K c qc, where K c is the empirical coefficient;

[0020] Poisson's ratio v is the ratio of the lateral deformation to the longitudinal deformation of the material. For sand, Poisson's ratio v = 0.25, for clay, Poisson's ratio v = 0.3;

[0021] Cohesion c is the consolidation force inside the soil. where K q is the empirical coefficient, qt is the lateral pressure measured by the static penetration test;

[0022] The friction angle φ describes the friction between soil particles.

[0023] The physical and mechanical parameters of each soil layer are combined into a preliminary model of the soil layer.

[0024] Preferably, the finite element method is used for inversion to simulate the interaction between the pile foundation and the underground soil layer. First, the underground soil layer and the pile foundation area are divided into a number of small units, such as triangular units, quadrilateral units, and hexahedral units, to construct a grid.

[0025] According to the material properties of different soil layers and pile foundations, their elastic modulus, Poisson's ratio, cohesion and friction angle parameters are defined as follows: σ = E·ε, where σ is stress and ε is strain;

[0026] Set boundary conditions: Set boundary conditions based on the interaction between the pile foundation and the soil layer, such as fixing the top end of the pile foundation and setting the bottom of the soil layer as a free boundary or a fixed boundary. Apply loads: Apply external loads based on the top load, horizontal load, and pile friction of the pile.

[0027] Using the finite element method to solve the displacement field U 位移场 , that is, the displacement of each node; for each small unit, the shape function N is used to express the relationship between the node displacement and the unit displacement; it is assumed that the deformation of the unit is linearly related to the node displacement: U ε =N ε ·u; among them, U ε is the unit displacement, N ε is the shape function of the element, and u is the displacement vector of the node;

[0028] For each element, the element stiffness matrix K is calculated by the following formula ε : Where B is the strain-displacement matrix, D is the constitutive matrix of the material, and A ε is the unit area, B T is the transposed matrix of the strain-displacement matrix B, dA is the area element;

[0029] Based on the total stiffness matrix K and the load vector F, a linear equation system is constructed: K·U=F. Here, U is the displacement vector. Solving the equation system yields the node displacement vector U, which is then used to calculate the stress and strain of the soil and the force applied to the pile foundation. Based on the calculated stress, strain, and displacement data, the interaction between the pile foundation and the soil layer is analyzed, and the bearing capacity and deformation of the pile foundation are evaluated.

[0030] Preferably, a function is determined for the inversion objective: the inversion objective is to match the output of the numerical model with the actual observation data through an optimization algorithm; a least squares objective function is used: Among them, x 2 is the objective function value, y i is the observation data, is the model prediction data, σ i is the standard deviation of the observed data, and N is the total number of data points;

[0031] Optimization algorithm: used to minimize the objective function and adjust the model parameters to make the numerical simulation results as close as possible to the observed data; the formula used is: θ k+1 =θ k -α▽x 2 (θ k ), where θ k is the current parameter value, α is the learning rate, ▽x 2 (θ k ) is the gradient of the objective function;

[0032] When the inversion problem is ill-posed, that is, the model has multiple solutions; in order to prevent overfitting and ensure model stability, regularization technology is used, and the formula is: Among them, ||m|| is the bi-norm of the model parameters, and λ is the regularization parameter;

[0033] The optimization algorithm is used to minimize the objective function, and the model parameters are updated through an iterative process to gradually approach the optimal solution. In each iteration, the output of the model is compared with the observed data, and the parameters are adjusted until the accuracy requirements are met. The inversion results are verified by the root mean square error. Here, RMSE is the root mean square error.

[0034] Preferably, the fusion of different data sources in step 4 further adopts a weighted average method, assigning a weight to each data source, where the weight is proportional to the accuracy and reliability of the data: Among them, Fused Data i is the final estimated value of the i-th data after fusion, Is a summation symbol, which means the sum of all items from -i to m, w k is the weight of the k-th data source, is the value of the i-th data point in the k-th data source.

[0035] Preferably, in step 5, the depth of different soil layers and the thickness of each layer are obtained by inversion analysis; the depth of the soil layer is expressed by the formula: i =z i-1 +h i ; Among them, z i is the bottom depth of the i-th soil layer, z i-1 is the bottom depth of the previous soil layer, h i is the thickness of the i-th soil layer;

[0036] Based on the soil properties calculated by inversion, the stress distribution in the soil layer and the stress field around the pile foundation are further calculated; the calculation formula used is: Where σ0 is the stress applied on the surface, z is the depth, z′ is the integral variable, and d is the differential sign;

[0037] Let the objective function be x 2 , such as pile foundation settlement and bearing capacity, the influencing parameter is x i , such as the elastic modulus and friction angle of the soil layer; local sensitivity is obtained by calculating the partial derivatives of the objective function with respect to each parameter: in, Represents parameter x i For the target function x 2 By calculating the sensitivity of each parameter, we can understand the impact of each parameter on the objective function.

[0038] Preferably, the judgment of the inversion analysis: the judgment of the thickness and depth of the soil layer, the soil layer thickness in the inversion result is compared with the actual exploration data layer by layer, the thickness difference of each layer is checked, and for the part with large thickness difference, whether it is related to the geological conditions, the inversion model or the measurement error is analyzed;

[0039] Check the depth of each soil layer to ensure that it matches the description of the actual geological profile. If the depth differs significantly from the actual data, consider whether it reflects the heterogeneity of the soil layer or model errors in the inversion process.

[0040] When the inversion results are consistent with the actual data, it means that the inversion process is relatively accurate and the soil layer parameters are reasonably set; if there are large differences, the inversion model settings should be re-evaluated and the boundary conditions and initial assumptions of the inversion should be adjusted.

[0041] Optimally, stress distribution comparison and judgment: Based on the stress distribution of each layer in the inversion results, check whether it meets the bearing capacity requirements of the theoretical model and the actual soil layer; stress increases with increasing depth, and if unreasonable stress distribution occurs, the cause needs to be analyzed;

[0042] Based on the different properties of the soil layers, determine whether the horizontal stress is reasonably distributed with the change of depth and soil type. The horizontal stress of the clay layer may be different from that of the sand layer. Therefore, a comparison is made based on the friction resistance characteristics of the soil to ensure that the inversion results are reasonable.

[0043] When the stress distribution obtained by inversion is consistent with the expected physical laws, it means that the inversion result is relatively reasonable; if the stress distribution is abnormal, it is necessary to check the parameter settings in the inversion process or whether the stress model is appropriate;

[0044] Comparison of bearing capacity and settlement: Compare the bearing capacity calculated based on the inversion results with the requirements in the design specifications to check whether the inversion results are safe enough. For structures with high bearing requirements for pile foundations and subgrades, the bearing capacity must meet the safety factor requirements in the specifications. Based on the soil stress in the inversion results, calculate the settlement caused by the load applied by the pile foundation or structure to ensure that the settlement does not exceed the requirements of the specifications.

[0045] When both the bearing capacity and settlement meet the design requirements, the inversion results are highly reliable. If it is found that the bearing capacity or settlement exceeds the specification requirements, the soil layer parameters and load distribution should be reviewed and the model adjusted to optimize the design.

[0046] The beneficial effects of the present invention are:

[0047] It can provide accurate geological exploration data, infer the specific characteristics of the underground soil through inversion methods, and provide precise parameters for pile foundation design. Simultaneously, the finite element method is used to simulate the interaction between the pile foundation and the soil layer, predicting deformation and stress distribution during construction, providing a scientific basis for engineering design. Furthermore, real-time monitoring of pile foundation settlement and pile driving resistance is required to enable timely adjustments to the construction plan to ensure construction safety and quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 A schematic diagram of the structure of an inversion method for pile foundation construction and geological exploration technology;

[0049] Figure 2 A flow chart of the static penetration test operation for an inversion method of pile foundation construction and geological exploration technology;

[0050] Figure 3 The present invention is a flowchart for analyzing and judging the inversion data results of an inversion method for pile foundation construction and geological exploration technology. DETAILED DESCRIPTION

[0051] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0052] Reference Figure 1-Figure 3 , an inversion method for pile foundation construction and geological exploration technology, including the following steps: step 1, geological exploration data collection; through drilling and in-situ testing operations, obtaining the property data of the underground soil layer, including the thickness, density, and soil type of the soil layer; and calculating the values ​​of the thickness, density, and soil type of the soil layer through a static penetration test method.

[0053] The operation steps of the static penetration test in step 1 are as follows: a1. Before the test, drill a hole at the designated location to determine the depth of the hole;

[0054] a2. Use a static cone penetration instrument to push the probe vertically into the underground soil layer. The probe is equipped with multiple sensors;

[0055] a3. The front end of the probe has a conical tip with a pressure sensor. As the probe penetrates into the soil, the pressure sensor records the penetration resistance and friction resistance of the soil.

[0056] Cone penetration resistance qc: The resistance generated when the measuring probe enters the soil layer. The formula is: Among them, F cone is the pressure recorded by the cone tip sensor, A cone is the contact area of ​​the cone tip;

[0057] Friction resistance fs: is the resistance caused by friction between the probe side and the soil layer. The formula is: Among them, F fric is the force recorded by the side friction sensor, A fric is the contact area of ​​lateral friction;

[0058] a4. The resistance data generated by different depths of the soil layer will be recorded in real time to form the mechanical response data of the soil layer; by analyzing the cone penetration resistance qc and friction resistance fs, the type and density of the soil layer will be evaluated; the ratio Among them, Rf < 0.5 indicates sandy soil or loose soil, and Rf > 1.0 indicates clay or high-clay soil.

[0059] Static penetration tests provide accurate and in-depth data support for soil exploration, enabling precise assessment of subsurface soil properties, density, and bearing capacity. This information is crucial for pile foundation design, helping to optimize construction plans, improve project safety, and reduce costs. Furthermore, real-time soil mechanics data provides a scientific basis for subsequent construction, ensuring smooth project progress. This approach enables engineering designers to make more accurate decisions and effectively mitigate potential risks and uncertainties.

[0060] Step 2: Monitoring of pile foundation construction, monitoring of pile settlement and pile sinking resistance; Pile settlement monitoring in step 2 mainly measures the vertical displacement of the pile top. Pile settlement is the deformation of the pile body after bearing the load. The settlement formula used is: Where S is the settlement, P is the load on the pile top, A is the cross-sectional area of ​​the pile, L is the length of the pile, and E is the elastic modulus of the pile soil;

[0061] The pile sinking resistance in step 2 is calculated by measuring the resistance the pile encounters during the sinking process. The pile sinking resistance is related to the shear strength of the soil layer and is calculated using the formula: R = ∑(τ × A 面积 ), where τ is the shear strength of the soil layer, A 面积 is the contact area of ​​the soil layer.

[0062] It can effectively evaluate the performance of pile foundations during loading. By measuring the settlement of the pile top, it is possible to promptly detect whether the pile foundation meets the design requirements and avoid structural safety problems caused by excessive settlement. At the same time, monitoring the pile driving resistance helps to understand the shear strength of the soil layer and the pile-soil interaction, ensuring that the pile foundation can be smoothly driven in and firmly positioned during the construction process. Overall, the settlement monitoring and pile driving resistance monitoring of the pile foundation provide a scientific basis for quality control during the construction process, which can identify potential problems in advance, ensure project safety, improve construction efficiency and reduce unnecessary risks.

[0063] Step 3: Inversion operation, by inverting the geological exploration data obtained in step 1 and the monitoring data of the pile foundation construction obtained in step 2, the specific characteristics of the underground soil layer are inferred. In the inversion operation step of step 3, the soil layer is first divided according to the data obtained in steps 1 and 2, and the physical parameters of each layer of soil are determined, including density, moisture content and effective stress; and the mechanical parameters of the soil layer are then determined, including elastic modulus, Poisson's ratio, cohesion and friction angle.

[0064] Elastic modulus E 模量 Indicates the stiffness of the soil layer: E 模量 =K c qc, where K c is the empirical coefficient;

[0065] Poisson's ratio v is the ratio of the lateral deformation to the longitudinal deformation of the material. For sand, Poisson's ratio v = 0.25, for clay, Poisson's ratio v = 0.3;

[0066] Cohesion c is the consolidation force inside the soil. where K q is the empirical coefficient, qt is the lateral pressure measured by the static penetration test;

[0067] The friction angle φ describes the friction between soil particles.

[0068] The physical and mechanical parameters of each soil layer are combined into a preliminary model of the soil layer.

[0069] The finite element method is used for inversion to simulate the interaction between the pile foundation and the underground soil layer. First, the underground soil layer and the pile foundation area are divided into several small units, such as triangular units, quadrilateral units, and hexahedral units, to construct a grid.

[0070] According to the material properties of different soil layers and pile foundations, their elastic modulus, Poisson's ratio, cohesion and friction angle parameters are defined as follows: σ = E·ε, where σ is stress and ε is strain;

[0071] Set boundary conditions: Set boundary conditions based on the interaction between the pile foundation and the soil layer, such as fixing the top end of the pile foundation and setting the bottom of the soil layer as a free boundary or a fixed boundary. Apply loads: Apply external loads based on the top load, horizontal load, and pile friction of the pile.

[0072] Using the finite element method to solve the displacement field U 位移场 , that is, the displacement of each node; for each small unit, the shape function N is used to express the relationship between the node displacement and the unit displacement; it is assumed that the deformation of the unit is linearly related to the node displacement: U ε =N ε ·u; among them, U ε is the unit displacement, N ε is the shape function of the element, and u is the displacement vector of the node;

[0073] For each element, the element stiffness matrix K is calculated by the following formula ε : Where B is the strain-displacement matrix, D is the constitutive matrix of the material, and A ε is the unit area, B T is the transposed matrix of the strain-displacement matrix B, dA is the area element;

[0074] Based on the total stiffness matrix K and the load vector F, a linear equation system is constructed: K·U=F; where U is the displacement vector. Solving this system of equations yields the node displacement vector U, which is then used to calculate the stress and strain of the soil and the force acting on the pile foundation. Based on the calculated stress, strain, and displacement data, the interaction between the pile foundation and the soil layer is analyzed, and the bearing capacity and deformation of the pile foundation are evaluated.

[0075] Determine the function for the inversion objective: The inversion objective is to match the output of the numerical model with the actual observation data through the optimization algorithm; the least squares objective function is used: Among them, x 2 is the objective function value, y i is the observation data, is the model prediction data, σ iis the standard deviation of the observed data, and N is the total number of data points;

[0076] Optimization algorithm: used to minimize the objective function and adjust the model parameters to make the numerical simulation results as close as possible to the observed data; the formula used is: θ k+1 =θ k -α▽x 2 (θ k ), where θ k is the current parameter value, α is the learning rate, ▽x 2 (θ k ) is the gradient of the objective function;

[0077] When the inversion problem is ill-posed, that is, the model has multiple solutions; in order to prevent overfitting and ensure model stability, regularization technology is used, and the formula is: Among them, ||m|| is the bi-norm of the model parameters, and λ is the regularization parameter;

[0078] The optimization algorithm is used to minimize the objective function, and the model parameters are updated through an iterative process to gradually approach the optimal solution. In each iteration, the output of the model is compared with the observed data, and the parameters are adjusted until the accuracy requirements are met. The inversion results are verified by the root mean square error. Here, RMSE is the root mean square error.

[0079] Through inversion operations, accurate physical and mechanical parameters of underground soil layers can be obtained, thus providing a solid foundation for pile foundation design. By numerically simulating the interaction between pile foundation and soil layer, the bearing capacity and deformation of pile foundation can be more accurately evaluated. The precise soil layer model obtained through inversion can optimize pile foundation design and improve the safety and economy of the project. Regularization processing and iteration of optimization algorithms can avoid overfitting and ensure the stability and reliability of inversion results.

[0080] Inversion technology infers subsurface soil properties by combining numerical simulation, optimization algorithms, and observational data. The entire process includes establishing a geological model, collecting data, constructing an objective function, selecting an optimization algorithm, introducing regularization, performing inversion calculations, validating the results, and applying them. This series of steps allows accurate inference of the physical and mechanical properties of subsurface soils, enabling optimized engineering designs.

[0081] Step 4: In order to obtain the optimal underground soil characteristics during the inversion process, different data sources are fused. The fusion of different data sources in step 4 also uses the weighted average method to assign a weight to each data source. The weight is proportional to the accuracy and reliability of the data: Among them, Fused Data i is the final estimated value of the i-th data after fusion, Is a summation symbol, which means the sum of all items from -i to m, w k is the weight of the k-th data source, is the value of the i-th data point in the k-th data source.

[0082] The weighted average method can better utilize the advantages of each data source by assigning reasonable weights to different data sources, reduce the negative impact of unreliable data on the final estimation results, and thus improve the accuracy of the estimation of underground soil characteristics; by assigning appropriate weights according to the accuracy and reliability of each data source, more accurate data can occupy a larger share in the fusion process, effectively improving the reliability of the final result; by fusing and optimizing data from different sources, the deviation of a single data source can be avoided from having an excessive impact on the inversion results, thereby enhancing the stability and reliability of the model; the fusion of different data sources can cover more geological information and pile foundation monitoring data, making the model more comprehensive and adaptable to the pile foundation design requirements under different geological conditions, and having stronger practicality.

[0083] Step 5: Analyze and judge the inversion data results; in step 5, the depth of different soil layers and the thickness of each layer are obtained through inversion analysis; the depth of the soil layer is expressed by the formula: i =z i-1 +h i ; Among them, z i is the bottom depth of the i-th soil layer, z i-1 is the bottom depth of the previous soil layer, h i is the thickness of the i-th soil layer;

[0084] Based on the soil properties calculated by inversion, the stress distribution in the soil layer can be further calculated, especially the stress field around the pile foundation; the calculation formula used is: Where σ0 is the stress applied on the surface, z is the depth, z′ is the integral variable, and d is the differential sign;

[0085] Let the objective function be x 2 , such as pile foundation settlement and bearing capacity, the influencing parameter is x i , such as the elastic modulus and friction angle of the soil layer; local sensitivity can be obtained by calculating the partial derivatives of the objective function with respect to each parameter: in, Represents parameter x i For the target function x 2 By calculating the sensitivity of each parameter, we can understand the impact of each parameter on the objective function.

[0086] Judgment of inversion analysis: Judgment of soil layer thickness and depth. Compare the soil layer thickness in the inversion results with the actual exploration data layer by layer, check the thickness difference of each layer, and analyze whether the parts with large thickness differences are related to geological conditions, inversion model or measurement errors;

[0087] Check the depth of each soil layer to ensure that it matches the description of the actual geological profile. If the depth differs significantly from the actual data, consider whether it reflects the heterogeneity of the soil layer or model errors in the inversion process.

[0088] When the inversion results are consistent with the actual data, it means that the inversion process is relatively accurate and the soil layer parameters are reasonably set; if there are large differences, the inversion model settings should be re-evaluated and the boundary conditions and initial assumptions of the inversion should be adjusted.

[0089] Comparative judgment of stress distribution: Based on the stress distribution of each layer in the inversion results, check whether it meets the bearing capacity requirements of the theoretical model and the actual soil layer. Stress increases with increasing depth. If unreasonable stress distribution occurs, the cause needs to be analyzed.

[0090] Based on the different properties of the soil layers, determine whether the horizontal stress is reasonably distributed with the change of depth and soil type. The horizontal stress of the clay layer may be different from that of the sand layer. Therefore, a comparison is made based on the friction resistance characteristics of the soil to ensure that the inversion results are reasonable.

[0091] When the stress distribution obtained by inversion is consistent with the expected physical laws, it means that the inversion result is relatively reasonable; if the stress distribution is abnormal, it is necessary to check the parameter settings in the inversion process or whether the stress model is appropriate;

[0092] Comparison of bearing capacity and settlement: Compare the bearing capacity calculated based on the inversion results with the requirements in the design specifications to check whether the inversion results are safe enough. For structures with high bearing requirements for pile foundations and subgrades, the bearing capacity must meet the safety factor requirements in the specifications. Based on the soil stress in the inversion results, calculate the settlement caused by the load applied by the pile foundation or structure to ensure that the settlement does not exceed the requirements of the specifications.

[0093] When both the bearing capacity and settlement meet the design requirements, the inversion results are highly reliable. If it is found that the bearing capacity or settlement exceeds the specification requirements, the soil layer parameters and load distribution should be reviewed and the model adjusted to optimize the design.

[0094] Comparing the inversion results layer by layer with actual exploration data effectively assesses their reliability. If the inverted soil layer depth and thickness match the actual geological conditions, the model setup is reasonable and the inversion process is relatively accurate. If there are significant discrepancies, soil heterogeneity or model assumptions need to be re-examined to ensure that the inversion results are as close to reality as possible. The inversion-calculated stress distribution allows for the stress field at different depths and soil layer types to be checked to ensure compliance with physical laws and bearing capacity requirements. A reasonable stress distribution prevents excessive compression or deformation in the soil layer, effectively supporting the stability of the structure. Comparing the inversion-calculated bearing capacity and settlement results with design specifications verifies the safety and feasibility of the inversion data. If both bearing capacity and settlement meet the requirements, the inversion results have high practical application value. If not, soil layer parameters or the load model need to be adjusted to ensure structural stability and safety. Inversion analysis provides a quantitative assessment of soil properties, which helps optimize design and improve the safety and cost-effectiveness of civil engineering construction. Comparison and sensitivity analysis can identify key influencing factors and ensure the long-term stability and reliability of the structure.

[0095] Through drilling, in-situ testing and static penetration tests, detailed data on underground soil properties are obtained to provide an accurate basis for pile foundation design and reduce uncertainty in the construction process; settlement and pile driving resistance monitoring during pile foundation construction can provide real-time feedback on soil conditions, facilitating timely adjustment of construction plans and avoiding potential safety risks; through inversion calculation of the specific characteristics of underground soil layers, more accurate parameters are provided for pile foundation design, optimizing pile foundation layout and design, and improving the economy and rationality of the project; the finite element method is used to simulate the interaction between pile foundation and soil layer, predict deformation and stress distribution during construction, and provide a scientific basis for engineering design; through precise geological exploration and inversion analysis, the trial and error costs during construction are reduced and construction efficiency is improved; real-time monitoring and data analysis help to quickly identify and respond to problems, shorten the construction period, and reduce construction costs.

[0096] By comparing the inversion results with actual data, the project quality is ensured to meet the design specifications and safety requirements; inversion analysis and data fusion provide a basis for continuous quality improvement and promote the continuous improvement of project quality; precise geological exploration and optimized design help to reduce interference with the surrounding environment and achieve green construction; this technical solution combines multiple disciplines such as geological exploration, pile foundation construction, and data analysis, promoting multidisciplinary technological innovation and integration; the inversion method of pile foundation construction and geological detection technology has significant benefits and effects in improving construction accuracy, optimizing engineering design, improving construction efficiency, ensuring project quality, enhancing environmental friendliness, and promoting technological innovation and progress.

[0097] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. An inversion method for pile foundation construction and geological exploration technology, characterized by: The method includes the following steps: Step 1: geological exploration data collection; obtaining underground soil layer property data, including soil layer thickness, density, and soil type, through drilling and in-situ testing operations; The thickness, density and soil type of the soil layer are calculated by using the static penetration test method; Step 2: Monitoring of pile foundation construction, monitoring of pile settlement and pile sinking resistance; Step 3: Inversion operation, by inverting the geological exploration data obtained in step 1 and the monitoring data of the pile foundation construction obtained in step 2, the specific characteristics of the underground soil layer are calculated; Step 4: In order to obtain the optimal underground soil characteristics during the inversion process, different data sources are integrated; Step 5: Analyze and judge the inversion data results.

2. The inversion method of pile foundation construction and geological exploration technology according to claim 1 is characterized by: The static penetration test operation steps in step 1 are as follows: a1. Before the test, a hole is drilled at a designated location to determine the depth of the hole; a2. Use a static cone penetration instrument to push the probe vertically into the underground soil layer. The probe is equipped with multiple sensors; a3. The front end of the probe has a conical tip with a pressure sensor; As the probe penetrates deeper into the soil, the pressure sensor records the penetration resistance and friction resistance of the soil; Cone penetration resistance qc: The resistance generated when the measuring probe enters the soil layer. The formula is: Among them, F cone is the pressure recorded by the cone tip sensor, A cone is the contact area of ​​the cone tip; Friction resistance fs: is the resistance caused by friction between the probe side and the soil layer. The formula is: Among them, F fric is the force recorded by the side friction sensor, A fric is the contact area of ​​lateral friction; a4. The resistance data generated by different depths of the soil layer will be recorded in real time to form the mechanical response data of the soil layer; by analyzing the cone penetration resistance qc and friction resistance fs, the type and density of the soil layer will be evaluated; the ratio Among them, Rf < 0.5 indicates sandy soil or loose soil, and Rf > 1.0 indicates clay or high-clay soil.

3. The inversion method of pile foundation construction and geological exploration technology according to claim 2, characterized in that: The settlement monitoring of the pile in step 2 mainly measures the vertical displacement of the pile top. The settlement of the pile is the deformation of the pile body after bearing the load. The settlement formula is: Where S is the settlement, P is the load on the pile top, A is the cross-sectional area of ​​the pile, L is the length of the pile, and E is the elastic modulus of the pile soil; The pile sinking resistance in step 2 is calculated by measuring the resistance the pile encounters during the sinking process. The pile sinking resistance is related to the shear strength of the soil layer and is calculated using the formula: R = ∑(τ × A 面积 ), where τ is the shear strength of the soil layer, A 面积 is the contact area of ​​the soil layer.

4. The inversion method of pile foundation construction and geological exploration technology according to claim 3 is characterized by: The inversion operation step in step 3 first divides the soil layers according to the data obtained in steps 1 and 2, and determines the physical parameters of each soil layer, including density, moisture content, and effective stress; and then determines the mechanical parameters of the soil layer, including elastic modulus, Poisson's ratio, cohesion, and friction angle; Elastic modulus E 模量 Indicates the stiffness of the soil layer: E 模量 =K c qc, where K c is the empirical coefficient; Poisson's ratio v is the ratio of the lateral deformation to the longitudinal deformation of the material. For sand, Poisson's ratio v = 0.25, for clay, Poisson's ratio v = 0.3; Cohesion c is the consolidation force inside the soil. where K q is the empirical coefficient, qt is the lateral pressure measured by the static penetration test; The friction angle φ describes the friction between soil particles. The physical and mechanical parameters of each soil layer are combined into a preliminary model of the soil layer.

5. The inversion method of pile foundation construction and geological exploration technology according to claim 4 is characterized in that: The finite element method is used for inversion to simulate the interaction between the pile foundation and the underground soil layer. First, the underground soil layer and the pile foundation area are divided into several small units, such as triangular units, quadrilateral units, and hexahedral units, to construct a grid. According to the material properties of different soil layers and pile foundations, their elastic modulus, Poisson's ratio, cohesion and friction angle parameters are defined as follows: σ = E·ε, where σ is stress and ε is strain; Set boundary conditions: Set boundary conditions based on the interaction between the pile foundation and the soil layer, such as fixing the top end of the pile foundation and setting the bottom of the soil layer as a free boundary or a fixed boundary. Apply loads: Apply external loads based on the top load, horizontal load, and pile friction of the pile. Using the finite element method to solve the displacement field U 位移场 , that is, the displacement of each node; for each small unit, the shape function N is used to express the relationship between the node displacement and the unit displacement; it is assumed that the deformation of the unit is linearly related to the node displacement: U ε =N ε ·u; among them, U ε is the unit displacement, N ε is the shape function of the element, and u is the displacement vector of the node; For each element, the element stiffness matrix is ​​calculated by the following formula Where B is the strain-displacement matrix, D is the constitutive matrix of the material, and A ε is the unit area, B T is the transposed matrix of the strain-displacement matrix B, dA is the area element; Based on the total stiffness matrix K and the load vector F, a linear equation system is constructed: K·U=F. Here, U is the displacement vector. Solving the equation system yields the node displacement vector U, which is then used to calculate the stress and strain of the soil and the force applied to the pile foundation. Based on the calculated stress, strain, and displacement data, the interaction between the pile foundation and the soil layer is analyzed, and the bearing capacity and deformation of the pile foundation are evaluated.

6. The inversion method of pile foundation construction and geological exploration technology according to claim 5, characterized in that: Determine the function for the inversion objective: The inversion objective is to match the output of the numerical model with the actual observation data through the optimization algorithm; the least squares objective function is used: Among them, x 2 is the objective function value, y i is the observation data, is the model prediction data, σ i is the standard deviation of the observed data, and N is the total number of data points; Optimization algorithm: used to minimize the objective function and adjust the model parameters to make the numerical simulation results as close as possible to the observed data; the formula used is: Among them, θ k is the current parameter value, α is the learning rate, is the gradient of the objective function; When the inversion problem is ill-posed, that is, the model has multiple solutions; in order to prevent overfitting and ensure model stability, regularization technology is used, and the formula is: Among them, ||m|| is the bi-norm of the model parameters, and λ is the regularization parameter; The optimization algorithm is used to minimize the objective function, and the model parameters are updated through an iterative process to gradually approach the optimal solution. In each iteration, the output of the model is compared with the observed data, and the parameters are adjusted until the accuracy requirements are met. The inversion results are verified by the root mean square error. Here, RMSE is the root mean square error.

7. The inversion method of pile foundation construction and geological exploration technology according to claim 6, characterized in that: The fusion of different data sources in step 4 also uses a weighted average method to assign a weight to each data source, and the weight is proportional to the accuracy and reliability of the data: Among them, Fused Data i is the final estimated value of the i-th data after fusion, Is a summation symbol, which means the sum of all items from -i to m, w k is the weight of the k-th data source, is the value of the i-th data point in the k-th data source.

8. The inversion method of pile foundation construction and geological exploration technology according to claim 7, characterized in that: In step 5, the depth of different soil layers and the thickness of each layer are obtained through inversion analysis; the depth of the soil layer is expressed by the formula: i =z i-1 +h i ; Among them, z i is the bottom depth of the i-th soil layer, z i-1 is the bottom depth of the previous soil layer, h i is the thickness of the i-th soil layer; Based on the soil properties calculated by inversion, the stress distribution in the soil layer and the stress field around the pile foundation are further calculated; the calculation formula used is: Where σ0 is the stress applied on the surface, z is the depth, z′ is the integral variable, and d is the differential sign; Let the objective function be x 2 , such as pile foundation settlement and bearing capacity, the influencing parameter is x i , such as the elastic modulus and friction angle of the soil layer; local sensitivity is obtained by calculating the partial derivatives of the objective function with respect to each parameter: in, Represents parameter x i For the target function x 2 By calculating the sensitivity of each parameter, we can understand the impact of each parameter on the objective function.

9. The inversion method of pile foundation construction and geological exploration technology according to claim 8, characterized in that: Judgment of inversion analysis: Judgment of soil layer thickness and depth. Compare the soil layer thickness in the inversion results with the actual exploration data layer by layer, check the thickness difference of each layer, and analyze whether the parts with large thickness differences are related to geological conditions, inversion model or measurement errors; Check the depth of each soil layer to ensure that it matches the description of the actual geological profile. If the depth differs significantly from the actual data, consider whether it reflects the heterogeneity of the soil layer or model errors in the inversion process. When the inversion results are consistent with the actual data, it means that the inversion process is relatively accurate and the soil layer parameters are reasonably set; If there are large differences, the inversion model settings should be re-evaluated and the boundary conditions and initial assumptions of the inversion should be adjusted.

10. The inversion method of pile foundation construction and geological exploration technology according to claim 9, characterized in that: Comparative judgment of stress distribution: Based on the stress distribution of each layer in the inversion results, check whether it meets the bearing capacity requirements of the theoretical model and the actual soil layer. Stress increases with increasing depth. If unreasonable stress distribution occurs, the cause needs to be analyzed. Based on the different properties of the soil layers, determine whether the horizontal stress is reasonably distributed with the change of depth and soil type. The horizontal stress of the clay layer may be different from that of the sand layer. Therefore, a comparison is made based on the friction resistance characteristics of the soil to ensure that the inversion results are reasonable. When the stress distribution obtained by inversion is consistent with the expected physical law, it means that the inversion result is reasonable; If the stress distribution is abnormal, it is necessary to check the parameter settings during the inversion process or whether the stress model is appropriate; Comparison of bearing capacity and settlement: Compare the bearing capacity calculated based on the inversion results with the requirements in the design specifications to check whether the inversion results are safe enough. For structures with high bearing requirements for pile foundations and subgrades, the bearing capacity must meet the safety factor requirements in the specifications. Based on the soil stress in the inversion results, calculate the settlement caused by the load applied by the pile foundation or structure to ensure that the settlement does not exceed the requirements of the specifications. When both the bearing capacity and settlement meet the design requirements, it indicates that the inversion results are highly reliable; If the bearing capacity or settlement is found to exceed the code requirements, the soil parameters and load distribution should be reviewed and the model adjusted to optimize the design.

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