Existing subway structure stress deformation assessment method under urban tunnel proximity construction

Abstract

The invention discloses an existing subway structure stress deformation assessment method and system under urban tunnel proximity construction, and the method comprises the steps: collecting stratum physical and mechanical parameters, existing subway structure design parameters and tunnel construction key parameters of an urban tunnel proximity construction influence region, and carrying out the integration to form a three-dimensional basic database; the method comprises the following steps: arranging equipment at key monitoring points to collect and preprocess real-time data, establishing a three-dimensional geology-structure numerical model based on a database, constructing an inversion algorithm by taking the preprocessed data as a target function, dynamically inverting real-time stratum parameters, and updating the database. The method comprises the following steps: constructing a stress deformation prediction model by combining real-time stratum parameters, inputting parameters to solve stress and deformation values of structures in different construction stages, setting an early warning threshold according to safety levels and specifications, comparing and outputting early warning levels, calculating model errors regularly, and supplementing sample retraining to realize dynamic iterative optimization if the early warning levels exceed the range. And safety and stability of the existing subway structure during construction are effectively guaranteed.

Description

Technical Field

[0001] This invention belongs to the field of urban underground engineering construction safety assessment and risk management technology, and more specifically, relates to a method and system for assessing the stress and deformation of existing subway structures under close-proximity construction of urban tunnels. Background Technology

[0002] In the process of urban construction, there is an increasing number of urban tunnels being built close to existing subway structures. This close-proximity construction can cause ground disturbance, which in turn can cause stress deformation of the existing subway structure. If the deformation exceeds the safe range, it will pose a serious threat to the safety of subway operation and even the urban transportation system.

[0003] Currently, there are many shortcomings in the assessment of stress and deformation of existing subway structures under close proximity construction of urban tunnels. On the one hand, there is a lack of systematic integration of multi-source data, including strata, existing subway structures, and tunnel construction data. The data is scattered and inconsistently formatted, making it difficult to conduct assessments efficiently. On the other hand, traditional assessment methods often rely on static assumptions about strata parameters, failing to reflect the dynamic changes in strata mechanical properties during construction, leading to discrepancies between assessment results and actual conditions. Furthermore, the existing assessment system is also lacking in constructing a closed-loop system covering the entire process from stress and deformation prediction to risk warning, making it difficult to achieve dynamic and timely control over the safety of existing subway structures.

[0004] The safety of existing subway structures during close-proximity construction of urban tunnels is crucial to the normal operation of urban transportation and the safety of people's lives and property. Failure to accurately assess stress and deformation and provide timely risk warnings could lead to severe social impacts and economic losses should structural damage or functional failure occur. Therefore, there is an urgent need for a method that can integrate multi-source data, dynamically update geological parameters, and achieve a closed-loop assessment throughout the entire process to ensure the safety and stability of existing subway structures during close-proximity construction of urban tunnels. This has significant practical implications for the safe development of urban underground space and the sustainable development of urban transportation. Summary of the Invention

[0005] This invention aims to address the problems of scattered stress and deformation assessment data, static ground parameters, and lack of full-process control in urban tunnel construction, where existing subway structures are often under stress and deformation. By integrating multi-source data, dynamically inverting ground parameters, and constructing a prediction and early warning closed loop, it achieves accurate assessment and dynamic risk control of existing subway structures, ensuring construction and subway operation safety.

[0006] To address the aforementioned deficiencies or improvement needs of existing technologies, as a first aspect of this invention, the present invention provides a method for evaluating the stress and deformation of existing subway structures under near-construction conditions of urban tunnels, characterized by comprising: S1. Collect the geological physical and mechanical parameters of the urban tunnel near the construction impact zone, the existing subway structure design parameters, and the key parameters of tunnel construction; divide the geological physical and mechanical parameters into geological zones according to the preset disturbance level and mark the parameter intervals; mark the key monitoring point information of the existing subway structure design parameters; clarify the construction stage division standards for the key parameters of tunnel construction according to the construction method; and integrate the above data to form a three-dimensional basic database. S2. Deploy equipment at key structural monitoring points to collect real-time monitoring data and preprocess it. Build a three-dimensional geological-structural numerical model based on a three-dimensional basic database. Construct an inversion algorithm and train the model using the preprocessed data as the objective function. Dynamically invert real-time stratigraphic parameters and update them to the database. S3. Based on the type of nearby construction, construct a corresponding stress and deformation prediction model by combining real-time stratum parameters, input real-time stratum parameters and key tunnel construction parameters, and solve for the stress and deformation values ​​of the existing subway structure at different construction stages. S4. Based on the existing subway structure safety level and related technical specifications, set early warning thresholds and construct a risk early warning model. Compare the stress deformation value, deformation rate and early warning threshold to output the early warning level. Calculate the model error periodically. If it exceeds the preset range, supplement the sample and retrain the relevant model to achieve dynamic iterative optimization.

[0007] Furthermore, the specific process in S1 of dividing the formation physical and mechanical parameters into formation zones and marking parameter intervals according to a preset disturbance level is as follows: Based on the initial geological physical and mechanical parameters of the urban tunnel's immediate construction impact zone, combined with key tunnel construction parameters, the geological zoning is divided into zones and parameter intervals are marked using the following mathematical relationships: Among them, the initial formation physical and mechanical parameters include cohesion. internal friction angle Elastic modulus Key parameters for tunnel construction include burial depth. Poisson's ratio of the strata First press Derivation of the construction influence radius ; Let the horizontal distance from any point in the stratum to the tunnel axis be... Define the degree of disturbance : , in, To add stress during construction, The initial effective stress of the formation is the ratio of the two values, which reflects the extent to which construction changes the stress state of the formation. This reflects the influence of spatial location on motion; the closer to the tunnel, the larger the coefficient, and the higher the degree of disturbance. Based on the disturbance degree function Stratigraphic zoning: when When it is the core disturbance area, This is a transitional influence zone, when The time is a stable region; based on The correlation with initial formation parameters is used to derive the parameter ranges for each zone: cohesion is calculated according to... Calculate the internal friction angle according to Calculation, elastic modulus according to The calculations, based on the above relationships, clarify the specific ranges of cohesion, internal friction angle, and elastic modulus within different zones.

[0008] Furthermore, the specific process of annotating the key monitoring point information of the existing subway structure design parameters in S1 is as follows: Based on existing subway structural design parameters and the proximity distance between the tunnel and the structure, the location of key monitoring points is determined by the coupling relationship between structural dimensions and proximity distance. For pile foundations that pass through elevated structures, the depth of the pile monitoring points is defined to meet the following requirements. ,in The length of the pile foundation. For close proximity, For the number of monitoring points, Take 1 to , This ensures that monitoring points are concentrated on the pile section most significantly affected by disturbance; For the section passing under the station roof slab, the coordinates of the monitoring points along the span direction satisfy the following conditions: ,in For the top slab span, For the number of monitoring points, Take 1 to And preferentially included and , These locations are the control nodes for structural stress.

[0009] Furthermore, the specific process of defining the construction stage division standards for key parameters of tunnel construction according to construction methods in S1 is as follows: Based on the pipe jacking method, define variables for dividing the construction stages. ,in This represents the cumulative length of the pipe jacking operation. For real-time jacking force, The cross-sectional area of ​​the jacking pipe is... The elastic modulus of the strata in the construction impact zone; when At the initial stage of construction, when At the time, it was in the middle stage of construction, when This was during the later stages of construction, in which The total design length of the jacking pipe is... The maximum design value for the jacking force; In shield tunneling construction, define variables for the construction stage division. ,in The cumulative number of rotations of the cutter head. To calculate the cumulative amount of grouting during synchronous injection. The cumulative excavation volume of the tunnel boring machine (TBM). The elastic modulus of the strata in the construction impact zone; when At the initial stage of construction, when At the time, it was in the middle stage of construction, when This was during the later stages of construction, in which Design the total number of rotations for the cutter head. The maximum grouting volume is designed to be that of the maximum grouting volume. The total excavation volume for the shield tunneling design.

[0010] Furthermore, the specific process of building a three-dimensional geological-structural numerical model based on a three-dimensional basic database in S2 is as follows: Based on a three-dimensional basic database, using the planar coordinates of the engineering area and elevation Constructing a three-dimensional spatial domain : , Among them, boundary values The extent of the tunnel construction impact zone is determined by the coupling of the existing subway structure distribution range; Stratigraphic partitioning, through characteristic functions Define spatial ownership: when Belongs to the When dividing the stratigraphy, Otherwise, it is 0, and satisfies , Set the total number of partitions and assign parameters: , , , in, Representing spatial points Cohesion, internal friction angle, and elastic modulus at the point of contact , , For the first Initial values ​​for the partition parameter range; For existing subway structures, using geometric equations Describe its spatial form, and through Mark key monitoring points, among which, For the Dirac function, The coordinates of the marked monitoring points; For the tunnel construction area, with It dynamically describes the construction space and enables spatiotemporal dynamic simulation of the construction process. Construction time; Finally, the mesh generation equation was used. Determine the unit dimensions to complete model building, where, The distance to the structural surface, Distance to the monitoring point This refers to the distance to the tunnel construction area.

[0011] Furthermore, the objective function in S2 is specifically: The objective function, centered on the dynamic coupling between real-time monitoring data and numerical model prediction results, is defined as the cumulative spatial difference between the measured values ​​and calculated values ​​of physical quantities at monitoring points. The formula is as follows: , in, The vector of formation parameters to be inverted; , The first and second marks are respectively the first and second marks. monitoring points Measured displacement and stress; , For three-dimensional geological-structural numerical models in terms of parameters The calculated value below; , These represent the maximum allowable displacement and stress of the structure corresponding to the monitoring point.

[0012] Furthermore, the stress-deformation prediction model in S3 is specifically as follows: The stress-deformation prediction model is based on the coupling relationship between the three-dimensional geological-structural numerical model and the dynamic characteristics of the construction stage. It establishes a prediction equation with the principle of virtual work as its core, and the expression is: , The left side represents the virtual work done by the internal forces of the structure and strata. For stress tensor, For the strain tensor, ":" represents the tensor double dot product; the first term on the right represents the virtual work done by the volume forces. The vector of volumetric forces equal to the self-weight of the strata. It is a displacement vector. The second term represents the virtual work done by the boundary forces during tunnel construction. for The defined construction area boundary, The boundary force vector varies with the construction stage, and is related to the construction stage variables. Association satisfies , For the maximum construction boundary force, for The maximum design value; The displacement field can be obtained by solving this equation. Furthermore, through geometric equations Obtain the strain field, It is a symmetric gradient operator; combined with constitutive relations Obtain the stress field. This is the formation stiffness matrix obtained through inversion.

[0013] Furthermore, the specific method for solving the stress and deformation values ​​of the existing subway structure at different construction stages in S3 is as follows: Define construction phase variables The boundary force vector of tunnel construction is expressed as , For the maximum construction boundary force, for Substituting the design maximum value into the virtual work equation, we get: , in, This represents the construction boundary of stage S. The stress tensor containing stage variables, and the inverted formation parameters Through constitutive relations Related; For the existing subway structure area, the equations are discretized using the Galerkin weighted residual method, resulting in a matrix form: , in, The overall stiffness matrix includes stage variables. For stage load vectors, The displacement vector of the structural nodes; Solving the equation yields The displacement values ​​of the marked monitoring points are extracted using an interpolation algorithm. , To monitor the shape function vector of the point; then use the stress recovery formula Calculate the force value , This is the strain-displacement transformation matrix for the monitoring point.

[0014] As a second aspect of the present invention, a stress and deformation assessment system for existing subway structures under close-proximity construction of urban tunnels is also provided, comprising: The three-dimensional basic database construction unit is used to collect the geological physical and mechanical parameters of the urban tunnel near the construction impact zone, the existing subway structure design parameters, and the key parameters of tunnel construction; the geological physical and mechanical parameters are divided into geological zones and parameter intervals are marked according to the preset disturbance level; the key monitoring point information of the existing subway structure design parameters is marked; the construction stage division standard of the key parameters of tunnel construction is defined according to the construction method; and the above data are integrated to form a three-dimensional basic database. The stratigraphic parameter inversion and update unit is used to deploy equipment at key structural monitoring points to collect real-time monitoring data and preprocess it. Based on the three-dimensional basic database, a three-dimensional geological-structural numerical model is built. The inversion algorithm is constructed and the model is trained using the preprocessed data as the objective function. Real-time stratigraphic parameters are dynamically inverted and updated to the database. The structural stress and deformation prediction unit is used to construct a corresponding stress and deformation prediction model based on the type of nearby construction and real-time stratum parameters. It inputs real-time stratum parameters and key tunnel construction parameters to solve the stress and deformation values ​​of the existing subway structure at different construction stages. The early warning and model optimization unit is used to set early warning thresholds and build risk early warning models based on the existing subway structure safety level and related technical specifications. It compares the stress deformation value, deformation rate and early warning threshold to output the early warning level, calculates the model error periodically, and supplements samples to retrain the relevant model to achieve dynamic iterative optimization if the error exceeds the preset range.

[0015] As a third aspect of the invention, a computer-readable storage medium is also provided, on which a computer program is stored, which is executed by a processor, according to any one of the claims, a method for evaluating the stress and deformation of existing subway structures under close-proximity construction of urban tunnels.

[0016] In summary, compared with the prior art, the above-described technical solutions conceived by this invention can achieve the following beneficial effects: 1. The present invention provides a method for assessing the stress and deformation of existing subway structures during near-construction of urban tunnels. This method collects geological physical and mechanical parameters, existing subway structure design parameters, and key tunnel construction parameters. It then divides the geological strata into zones, labels parameter intervals, marks key structural monitoring points, clarifies construction stage division standards, and integrates these into a three-dimensional basic database. This technical approach systematically integrates multi-source data from the engineering area, achieving spatial and staged organization of geological, structural, and construction parameters. It provides a unified and accurate basic data carrier for subsequent model building and analysis, ensuring the quality of the source data for the assessment and providing a reliable "data foundation" for subsequent stress and deformation analysis.

[0017] 2. The present invention provides a method for assessing the stress and deformation of existing subway structures during near-construction of urban tunnels. This method involves deploying equipment at key structural monitoring points to collect and preprocess real-time monitoring data. A three-dimensional geological-structural numerical model is then built based on a three-dimensional database. An inversion algorithm is constructed using the preprocessed data as the objective function, and the model is trained. Real-time geological parameters are dynamically inverted and updated to the database. This technical process deeply couples real-time monitoring data with the numerical model, dynamically correcting geological parameters through the inversion algorithm. This overcomes the shortcomings of static assumptions about geological parameters in traditional assessments, enabling the model to reflect the true mechanical properties of the strata during construction in real time. This provides dynamic and accurate parameter input for stress and deformation prediction, significantly improving the timeliness and accuracy of the assessment results.

[0018] 3. The present invention provides a method for assessing the stress and deformation of existing subway structures under close proximity construction of urban tunnels. This method constructs a stress and deformation prediction model by combining real-time geological parameters. By inputting real-time geological parameters and key tunnel construction parameters, it solves for the stress and deformation values ​​of existing subway structures at different construction stages. Simultaneously, it constructs a risk warning model based on pre-warning thresholds set according to specifications, compares and outputs warning levels, and dynamically iterates and optimizes the model. This technical approach achieves a closed-loop process from parameter input to stress and deformation prediction to risk warning. It can accurately quantify the stress and deformation state of the structure at different construction stages, and promptly identify risks and provide feedback for model optimization. This provides scientific and dynamic technical support for the safety management of existing subway structures under close proximity construction of urban tunnels, effectively ensuring the safety and stability of existing subway structures during construction. Attached Figure Description

[0019] Figure 1 This is a flowchart illustrating the method for evaluating the stress and deformation of existing subway structures under near-construction conditions of urban tunnels, as described in this embodiment of the invention. Figure 2 The figures show the ep curves of soft soil samples at different depths according to an embodiment of the present invention; a represents the depth of 3.15-3.55m; b represents the depth of 9.60-10.00m; c represents the depth of 15.20-15.40m; d represents the depth of 20.20-20.40m; e represents the void ratio; and p represents the pressure. Figure 3 This is a curve showing the variation of soil sample compression modulus with sampling depth according to an embodiment of the present invention; H is the burial depth; R is the coefficient of determination. Figure 4 This is a system unit diagram of an embodiment of the present invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0021] Example 1 Please refer to Figure 1 This embodiment 1 provides a method for evaluating the stress and deformation of existing subway structures under near-construction of urban tunnels, including: S1. Collect the geological physical and mechanical parameters of the urban tunnel near the construction impact zone, the existing subway structure design parameters, and the key parameters of tunnel construction; divide the geological physical and mechanical parameters into geological zones according to the preset disturbance level and mark the parameter intervals; mark the key monitoring point information of the existing subway structure design parameters; clarify the construction stage division standards for the key parameters of tunnel construction according to the construction method; and integrate the above data to form a three-dimensional basic database. S2. Deploy equipment at key structural monitoring points to collect real-time monitoring data and preprocess it. Build a three-dimensional geological-structural numerical model based on a three-dimensional basic database. Construct an inversion algorithm and train the model using the preprocessed data as the objective function. Dynamically invert real-time stratigraphic parameters and update them to the database. S3. Based on the type of nearby construction, construct a corresponding stress and deformation prediction model by combining real-time stratum parameters, input real-time stratum parameters and key tunnel construction parameters, and solve for the stress and deformation values ​​of the existing subway structure at different construction stages. S4. Based on the existing subway structure safety level and related technical specifications, set early warning thresholds and construct a risk early warning model. Compare the stress deformation value, deformation rate and early warning threshold to output the early warning level. Calculate the model error periodically. If it exceeds the preset range, supplement the sample and retrain the relevant model to achieve dynamic iterative optimization.

[0022] This embodiment 1 further elaborates on the above steps.

[0023] (1) Construction of three-dimensional basic database In urban tunnel near-construction scenarios, to accurately assess the stress and deformation of existing subway structures, it is necessary to first systematically collect core engineering data and standardize it to lay the foundation for subsequent analysis. The data collection scope covers the geological physical and mechanical parameters of the construction impact zone, the design parameters of the existing subway structure, and key tunnel construction parameters. This data is the core basis for the assessment work and can solve the problems of low analysis efficiency and large result bias caused by scattered and disorganized data sources in traditional assessments. For example, Figure 2 Soft soil at different depths Curve (porosity) With pressure (relationship) and Figure 3 The curve showing the change of soil sample compression modulus with sampling depth falls within the category of the physical and mechanical parameters of the strata that need to be collected. It presents in detail the compression law of soil at different depths under pressure and the spatial distribution law of compression modulus.

[0024] The data on the compression characteristics of strata at different depths provided by these charts are the direct basis for dividing strata into zones and marking parameter intervals. They provide underlying data support for building a three-dimensional basic database, subsequently building a geological-structural numerical model, and accurately predicting the stress and deformation of existing subway structures. This ensures that the assessment process can accurately reflect the impact of compression deformation of strata at different depths on existing structures and solves the problem of inaccurate parameter assignment caused by ignoring the spatial differences of strata in traditional assessments.

[0025] Secondly, regarding the physical and mechanical parameters of the strata, it is necessary to divide the strata into zones and clarify the parameter ranges based on the characteristics of construction disturbance. First, based on the initial strata parameters (such as the compression characteristic parameters at each depth shown in the table) and the key parameters of tunnel construction, the range of influence of construction on the strata is derived. Then, based on the distance from each point in the strata to the tunnel and the changes in construction stress, areas with different degrees of disturbance are defined, such as the core disturbance zone, the transitional influence zone, and the stable zone. At the same time, the range of values ​​for the strata mechanical parameters in each zone is determined.

[0026] Specifically, in a preferred embodiment, the process of dividing the formation physical and mechanical parameters into formation zones and marking parameter intervals according to a preset disturbance level is as follows: Based on the initial geological physical and mechanical parameters of the urban tunnel's immediate construction impact zone, combined with key tunnel construction parameters, the geological zoning is divided into zones and parameter intervals are marked using the following mathematical relationships: Among them, the initial formation physical and mechanical parameters include cohesion. internal friction angle Elastic modulus Key parameters for tunnel construction include burial depth. Poisson's ratio of the strata First press Derivation of the construction influence radius ; Let the horizontal distance from any point in the stratum to the tunnel axis be... Define the degree of disturbance : , in, Additional stress during construction (the ratio of jacking force to tunneling cross-sectional area is used for pipe jacking, and the difference between synchronous grouting pressure and initial pore water pressure is used for shield tunneling). The initial effective stress of the formation (obtained by multiplying the unit weight of the formation by the burial depth at that point) is the initial effective stress of the formation. The ratio of the two reflects the extent to which construction changes the stress state of the formation. This reflects the influence of spatial location on motion; the closer to the tunnel, the larger the coefficient, and the higher the degree of disturbance. Based on the disturbance degree function Stratigraphic zoning: when When it is the core disturbance area, This is a transitional influence zone, when The time is a stable region; based on The correlation with initial formation parameters is used to derive the parameter ranges for each zone: cohesion is calculated according to... Calculate the internal friction angle according to Calculation, elastic modulus according to The calculations, based on the above relationships, clarify the specific ranges of cohesion, internal friction angle, and elastic modulus within different zones.

[0027] For existing subway structural design parameters, it is necessary to focus on marking key monitoring points. Based on structural dimensions and proximity to the tunnel, monitoring points should be placed at the locations where the structure is most significantly disturbed. For example, when passing alongside elevated pile foundations, monitoring points should be placed on the pile sections most affected by construction; when passing under station roof slabs, monitoring points should be prioritized at critical stress nodes of the roof slab, such as the midpoint and ends of the span. Specifically, the process for marking key monitoring point information for existing subway structural design parameters is as follows: Based on existing subway structural design parameters and the proximity distance between the tunnel and the structure, the location of key monitoring points is determined by the coupling relationship between structural dimensions and proximity distance. For pile foundations that pass through elevated structures, the depth of the pile monitoring points is defined to meet the following requirements. ,in The length of the pile foundation. For close proximity, For the number of monitoring points, Take 1 to , This ensures that monitoring points are concentrated on the pile section most significantly affected by disturbance; For the section passing under the station roof slab, the coordinates of the monitoring points along the span direction satisfy the following conditions: ,in For the top slab span, For the number of monitoring points, Take 1 to And preferentially included and , These locations are the control nodes for structural stress.

[0028] For key parameters in tunnel construction, it is necessary to clarify the standards for dividing construction stages according to different construction methods. For pipe jacking, the construction stages are divided based on parameters such as the advancing length and jacking force; for shield tunneling, the construction progress is defined based on parameters such as the number of cutterhead rotations, grouting volume, and excavation volume. Specifically, the process of clarifying the standards for dividing construction stages based on key parameters of tunnel construction according to the construction method is as follows: Based on the pipe jacking method, define variables for dividing the construction stages. ,in This represents the cumulative length of the pipe jacking operation. For real-time jacking force, The cross-sectional area of ​​the jacking pipe is... The elastic modulus of the strata in the construction impact zone; when At the initial stage of construction, when At the time, it was in the middle stage of construction, when This was during the later stages of construction, in which The total design length of the jacking pipe is... The maximum design value for the jacking force; In shield tunneling construction, define variables for the construction stage division. ,in The cumulative number of rotations of the cutter head. To calculate the cumulative amount of grouting during synchronous injection. The cumulative excavation volume of the tunnel boring machine (TBM). The elastic modulus of the strata in the construction impact zone; when At the initial stage of construction, when At the time, it was in the middle stage of construction, when This was during the later stages of construction, in which Design the total number of rotations for the cutter head. The maximum grouting volume is designed to be that of the maximum grouting volume. The total excavation volume for the shield tunneling design.

[0029] By dividing the construction into stages, we can clearly understand the disturbance patterns of different construction stages on the surrounding strata and existing structures. This solves the problems of traditional assessments, such as the inability to dynamically match the construction progress and the difficulty in analyzing the risks of each stage. It also provides a clear time dimension reference for subsequent phased assessments of structural stress and deformation.

[0030] Through the above data collection and processing, the scattered engineering data is transformed into a structured and standardized three-dimensional basic database. This not only solves the problems of chaotic data management and low application efficiency in traditional assessments, but also provides a unified data carrier for subsequent model building, parameter inversion and other work, ensuring the continuity and accuracy of the entire assessment process, and providing scientific data support for the safety management of existing subway structures under close-proximity construction of urban tunnels.

[0031] (2) Formation parameter inversion update After completing the collection and standardization of core engineering data and forming a three-dimensional basic database, the next step is to rely on measured data and model construction to achieve dynamic correction of formation parameters, providing accurate parameter support for subsequent stress and deformation assessment. This step can solve the pain points of "data and model disconnect" and "static invariance of formation parameters" in traditional assessments, allowing assessments to shift from "empirical assumptions" to "data-driven" approaches.

[0032] First, equipment is deployed at the key structural monitoring points identified in the early stages to continuously collect real-time stress and deformation data of the structure. Then, preprocessing is used to remove invalid information such as environmental interference and equipment errors, resulting in valid data that truly reflects the structural state. This approach avoids subsequent analytical biases caused by data quality issues, ensures the reliability of the measured data input to the model, and solves the problem of "disorganized and unusable data" in traditional monitoring, providing a solid basis for subsequent model verification and parameter inversion.

[0033] Next, a three-dimensional geological-structural numerical model is built based on a three-dimensional database. The model first delineates the three-dimensional spatial range covering the tunnel construction impact zone and the existing subway structure. Then, according to the previously defined stratigraphic zones, it assigns corresponding mechanical parameters such as cohesion and internal friction angle to different areas. At the same time, it uses geometric equations to accurately reconstruct the spatial morphology of the existing subway structure (such as pile foundations and roof slabs) and marks the locations of key monitoring points. For the tunnel construction area, the model also introduces a time dimension to dynamically present the excavation range and working space at different construction stages. This solves the problem that static models cannot match the dynamic progress of construction, allowing the model to realistically simulate the dynamic disturbance process of construction on the surrounding environment.

[0034] Specifically, the process of building a three-dimensional geological-structural numerical model based on a three-dimensional basic database is as follows: Based on a three-dimensional basic database, using the planar coordinates of the engineering area and elevation Constructing a three-dimensional spatial domain : , Among them, boundary values The extent of the tunnel construction impact zone is determined by the coupling of the existing subway structure distribution range; Stratigraphic partitioning, through characteristic functions Define spatial ownership: when Belongs to the When dividing the stratigraphy, Otherwise, it is 0, and satisfies , Set the total number of partitions and assign parameters: , , , in, Representing spatial points Cohesion, internal friction angle, and elastic modulus at the point of contact , , For the first Initial values ​​for the partition parameter range; For existing subway structures, using geometric equations Describe its spatial form, and through Mark key monitoring points, among which, For the Dirac function, The coordinates of the marked monitoring points; For the tunnel construction area, with It dynamically describes the construction space and enables spatiotemporal dynamic simulation of the construction process. Construction time; Finally, the mesh generation equation was used. Determine the unit dimensions to complete model building, where, The distance to the structural surface, Distance to the monitoring point This refers to the distance to the tunnel construction area.

[0035] In model building, It is the geometric boundary equation of the existing subway structure, where The corresponding geometric morphology analytical expression for the structure: For columnar structures such as pile foundations, it can be expressed as follows: (plane equation) and The combination of (elevation range) is obtained through the center coordinates of the circle. ,radius and top and bottom elevations Precisely define the spatial extent of cylindrical pile foundations; for slab-like structures such as station roof slabs, this can be represented as... (Elevation equation) and , The combination of (planar range) is determined by the top elevation of the slab. and planar boundaries Define the spatial form of the flat roof.

[0036] It is the dynamic geometric boundary equation of the tunnel construction area, where Over time Dynamic updates: For shield tunnels, at a certain moment... The excavation profile can be represented as (plane equation) and The combination of (elevation range), where , for The coordinates of the tunnel axis endpoints at any given time (as excavation progresses). The outer diameter of the tunnel is represented by this equation, which reflects the excavation space range at different construction stages in real time, and is related to the construction stage variables in S1. pass Related For the total construction period, for (Design maximum value), to achieve dynamic matching between construction progress and spatial form.

[0037] Finally, using the preprocessed measured data as the core, an inversion algorithm is constructed and a model is trained. By comparing the differences between the measured values ​​at monitoring points and the calculated values ​​from the model, the formation parameters are corrected in reverse, and then the corrected real-time formation parameters are updated to the database. The specific objective function is as follows: The objective function, centered on the dynamic coupling between real-time monitoring data and numerical model prediction results, is defined as the cumulative spatial difference between the measured values ​​and calculated values ​​of physical quantities at monitoring points. The formula is as follows: , in, The vector of formation parameters to be inverted; , The first and second marks are respectively the first and second marks. monitoring points Measured displacement and stress; , For three-dimensional geological-structural numerical models in terms of parameters The calculated value below; , These represent the maximum allowable displacement and stress of the structure corresponding to the monitoring point.

[0038] This dynamic inversion method breaks the limitation of "unchanging formation parameters" in traditional assessments. It can track changes in formation mechanical properties in real time during construction, solve the problem of inaccurate predictions caused by parameter lag, and provide subsequent stress and deformation analysis with parameters that are more in line with actual working conditions, thereby further improving the accuracy and timeliness of assessment results.

[0039] (3) Prediction of structural stress and deformation After completing the dynamic inversion of geological parameters and updating the database, in order to accurately grasp the stress and deformation of the existing subway structure at each stage of construction, it is necessary to construct a stress and deformation prediction model by combining the nearby construction type and real-time geological parameters.

[0040] When constructing the model, the previous three-dimensional geological-structural numerical model was used as a foundation, combined with the dynamic characteristics of the construction stage, comprehensively considering the volumetric forces such as the self-weight of the strata and the dynamic boundary forces during tunnel construction. These dynamic boundary forces change with the construction stage; for example, the forces will change accordingly during construction progress or grouting operations. Through this model construction, the stress situation of the structure throughout the entire construction process can be realistically simulated, avoiding prediction deviations caused by neglecting dynamic forces during construction.

[0041] Specifically, the stress-deformation prediction model is as follows: The stress-deformation prediction model is based on the coupling relationship between the three-dimensional geological-structural numerical model and the dynamic characteristics of the construction stage. It establishes a prediction equation with the principle of virtual work as its core, and the expression is: , The left side represents the virtual work done by the internal forces of the structure and strata. For stress tensor, For the strain tensor, ":" represents the tensor double dot product; the first term on the right represents the virtual work done by the volume forces. The vector of volumetric forces equal to the self-weight of the strata. It is a displacement vector. The second term represents the virtual work done by the boundary forces during tunnel construction. for The defined construction area boundary, The boundary force vector varies with the construction stage, and is related to the construction stage variables. Association satisfies , For the maximum construction boundary force, for The maximum design value; The displacement field can be obtained by solving this equation. Furthermore, through geometric equations Obtain the strain field, It is a symmetric gradient operator; combined with constitutive relations Obtain the stress field. This is the formation stiffness matrix obtained through inversion.

[0042] Furthermore, when solving for the stress and deformation values ​​at different construction stages, the criteria for dividing the construction stages are first clarified, and the key construction parameters for the corresponding stages are input into the model. The model will then output the stress and deformation data for that stage. Simultaneously, the values ​​of key monitoring points of the existing subway structure are extracted, as these values ​​directly reflect the safety status of the structure at different construction stages. In a preferred embodiment, the specific method for solving the stress and deformation values ​​of the existing subway structure at different construction stages is as follows: Define construction phase variables The boundary force vector of tunnel construction is expressed as , For the maximum construction boundary force, for Substituting the design maximum value into the virtual work equation, we get: , in, This represents the construction boundary of stage S. The stress tensor containing stage variables, and the inverted formation parameters Through constitutive relations Related; For the existing subway structure area, the equations are discretized using the Galerkin weighted residual method, resulting in a matrix form: , in, The overall stiffness matrix includes stage variables. For stage load vectors, The displacement vector of the structural nodes; Solving the equation yields The displacement values ​​of the marked monitoring points are extracted using an interpolation algorithm. , To monitor the shape function vector of the point; then use the stress recovery formula Calculate the force value , This is the strain-displacement transformation matrix for the monitoring point.

[0043] This phased and targeted calculation provides a precise basis for judging whether there are safety risks in each construction stage, ensuring that if the stress or deformation approaches the safety threshold during construction, timely adjustments can be made to ensure the safety and stability of the existing subway structure during construction.

[0044] (4) Early warning and model optimization After solving for the stress and deformation values ​​of the existing subway structure, it is necessary to set early warning thresholds based on its safety level and relevant technical specifications, and construct a risk early warning model. This step is a crucial link in ensuring the safety of the existing subway structure, solving the problems of lacking clear risk judgment standards and untimely early warning in traditional assessments. It enables engineers to quickly identify the safety risk level during construction and provides a basis for decision-making.

[0045] When setting early warning thresholds, the safety level of the existing subway structure is considered, and the limit requirements for structural deformation and stress in relevant technical specifications are referenced to determine the early warning thresholds for different monitoring items (such as displacement and stress), including threshold standards for different levels such as early warning and alarm. For example, for the roof slab of a subway station, based on its structural form and safety level, it is determined at what displacement (in millimeters) an early warning is required, and at what displacement (in millimeters) an alarm is required.

[0046] When constructing a risk early warning model, the calculated stress-deformation values ​​and deformation rates are compared with the set early warning thresholds to output the corresponding early warning level. The model comprehensively considers the changes in multiple monitoring indicators to avoid misjudging risks based on a single indicator.

[0047] Meanwhile, to ensure the accuracy and timeliness of the model, the model error is calculated periodically. If the error exceeds the preset range, it indicates a deviation between the model and the actual situation. In this case, new monitoring samples need to be added to retrain the model, achieving dynamic iterative optimization. This ensures that the risk warning model always aligns with the actual engineering situation, improves the accuracy of risk identification, and safeguards the safety of existing subway structures during close proximity construction in urban tunnels.

[0048] Example 2 Please refer to Figure 4 This embodiment 2 also provides a stress and deformation assessment system for existing subway structures under close-proximity construction of urban tunnels, including: The three-dimensional basic database construction unit is used to collect the geological physical and mechanical parameters of the urban tunnel near the construction impact zone, the existing subway structure design parameters, and the key parameters of tunnel construction; the geological physical and mechanical parameters are divided into geological zones and parameter intervals are marked according to the preset disturbance level; the key monitoring point information of the existing subway structure design parameters is marked; the construction stage division standard of the key parameters of tunnel construction is defined according to the construction method; and the above data are integrated to form a three-dimensional basic database. The stratigraphic parameter inversion and update unit is used to deploy equipment at key structural monitoring points to collect real-time monitoring data and preprocess it. Based on the three-dimensional basic database, a three-dimensional geological-structural numerical model is built. The inversion algorithm is constructed and the model is trained using the preprocessed data as the objective function. Real-time stratigraphic parameters are dynamically inverted and updated to the database. The structural stress and deformation prediction unit is used to construct a corresponding stress and deformation prediction model based on the type of nearby construction and real-time stratum parameters. It inputs real-time stratum parameters and key tunnel construction parameters to solve the stress and deformation values ​​of the existing subway structure at different construction stages. The early warning and model optimization unit is used to set early warning thresholds and build risk early warning models based on the existing subway structure safety level and related technical specifications. It compares the stress deformation value, deformation rate and early warning threshold to output the early warning level, calculates the model error periodically, and supplements samples to retrain the relevant model to achieve dynamic iterative optimization if the error exceeds the preset range.

[0049] Example 3 This embodiment 3 also provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, it can implement any step of a method for evaluating the stress and deformation of existing subway structures under close-proximity construction of urban tunnels.

[0050] The computer-readable storage medium may include various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0051] For a description of the computer-readable storage medium provided in this application, please refer to the above method embodiments; further details will not be repeated here.

[0052] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for evaluating the stress and deformation of existing subway structures under near-construction of urban tunnels, characterized in that, include: S1. Collect geological physical and mechanical parameters, existing subway structural design parameters, and key tunnel construction parameters in the area of ​​urban tunnel construction impact. The geological physical and mechanical parameters of the strata are divided into strata zones and parameter intervals are marked according to the preset disturbance level. The key monitoring point information of the existing subway structure design parameters is marked. The construction stage division standard of the key parameters of tunnel construction is clarified according to the construction method. The above data are integrated to form a three-dimensional basic database. S2. Deploy equipment at key structural monitoring points to collect real-time monitoring data and preprocess it. Build a three-dimensional geological-structural numerical model based on a three-dimensional basic database. Construct an inversion algorithm and train the model using the preprocessed data as the objective function. Dynamically invert real-time stratigraphic parameters and update them to the database. S3. Based on the type of nearby construction, construct a corresponding stress and deformation prediction model by combining real-time stratum parameters, input real-time stratum parameters and key tunnel construction parameters, and solve for the stress and deformation values ​​of the existing subway structure at different construction stages. S4. Based on the existing subway structure safety level and related technical specifications, set early warning thresholds and construct a risk early warning model. Compare the stress deformation value, deformation rate and early warning threshold to output the early warning level. Calculate the model error periodically. If it exceeds the preset range, supplement the sample and retrain the relevant model to achieve dynamic iterative optimization.

2. The method for evaluating the stress and deformation of existing subway structures under near-construction of urban tunnels according to claim 1, characterized in that, The specific process in S1 of dividing the formation physical and mechanical parameters into formation zones and marking parameter intervals according to the preset disturbance level is as follows: Based on the initial geological physical and mechanical parameters of the urban tunnel's immediate construction impact zone, combined with key tunnel construction parameters, the geological zoning is divided into zones and parameter intervals are marked using the following mathematical relationships: Among them, the initial formation physical and mechanical parameters include cohesion. internal friction angle Elastic modulus Key parameters for tunnel construction include burial depth. Poisson's ratio of the strata First press Derivation of the construction influence radius ; Let the horizontal distance from any point in the stratum to the tunnel axis be... Define the degree of disturbance : ， in, To add stress during construction, The initial effective stress of the formation is the ratio of the two values, which reflects the extent to which construction changes the stress state of the formation. This reflects the influence of spatial location on motion; the closer to the tunnel, the larger the coefficient, and the higher the degree of disturbance. Based on the disturbance degree function Stratigraphic zoning: when When it is the core disturbance area, This is a transitional influence zone, when The time is a stable region; based on The correlation with initial formation parameters is used to derive the parameter ranges for each zone: cohesion is calculated according to... Calculate the internal friction angle according to Calculation, elastic modulus according to The calculations, based on the above relationships, clarify the specific ranges of cohesion, internal friction angle, and elastic modulus within different zones.

3. The method for evaluating the stress and deformation of existing subway structures under near-construction of urban tunnels according to claim 1, characterized in that, The specific process of annotating key monitoring point information of the existing subway structure design parameters in S1 is as follows: Based on existing subway structural design parameters and the proximity distance between the tunnel and the structure, the location of key monitoring points is determined by the coupling relationship between structural dimensions and proximity distance. For pile foundations that pass through elevated structures, the depth of the pile monitoring points is defined to meet the following requirements. ,in The length of the pile foundation. For close proximity, For the number of monitoring points, Take 1 to , This ensures that monitoring points are concentrated on the pile section most significantly affected by disturbance; For the section passing under the station roof slab, the coordinates of the monitoring points along the span direction satisfy the following conditions: ,in For the top slab span, For the number of monitoring points, Take 1 to And preferentially included and , These locations are the control nodes for structural stress.

4. The method for evaluating the stress and deformation of existing subway structures under near-construction of urban tunnels according to claim 1, characterized in that, The specific process for defining the construction stage division standards for key parameters of tunnel construction according to construction methods in S1 is as follows: Based on the pipe jacking method, define variables for dividing the construction stages. ,in This represents the cumulative length of the pipe jacking operation. For real-time jacking force, The cross-sectional area of ​​the jacking pipe is... The elastic modulus of the strata in the construction impact zone; when At the initial stage of construction, when At the time, it was in the middle stage of construction, when This was during the later stages of construction, in which The total design length of the jacking pipe is... The maximum design value for the jacking force; In shield tunneling construction, define variables for the construction stage division. ,in The cumulative number of rotations of the cutter head. To calculate the cumulative amount of grouting during synchronous injection. The cumulative excavation volume of the tunnel boring machine (TBM). The elastic modulus of the strata in the construction impact zone; when At the initial stage of construction, when At the time, it was in the middle stage of construction, when This was during the later stages of construction, in which Design the total number of rotations for the cutter head. The maximum grouting volume is designed to be that of the maximum grouting volume. The total excavation volume for the shield tunneling design.

5. The method for evaluating the stress and deformation of existing subway structures under near-construction of urban tunnels according to claim 1, characterized in that, The specific process of building a three-dimensional geological-structural numerical model based on a three-dimensional basic database in S2 is as follows: Based on a three-dimensional basic database, using the planar coordinates of the engineering area and elevation Constructing a three-dimensional spatial domain : ， Among them, boundary values The extent of the tunnel construction impact zone is determined by the coupling of the existing subway structure distribution range; Stratigraphic partitioning, through characteristic functions Define spatial ownership: when Belongs to the When dividing the stratigraphy, Otherwise, it is 0, and satisfies , Set the total number of partitions and assign parameters: ， ， ， in, Representing spatial points Cohesion, internal friction angle, and elastic modulus at the point of contact , , For the first Initial values ​​for the partition parameter range; For existing subway structures, using geometric equations Describe its spatial form, and through Mark key monitoring points, among which, For the Dirac function, The coordinates of the marked monitoring points; For the tunnel construction area, with It dynamically describes the construction space and enables spatiotemporal dynamic simulation of the construction process. Construction time; Finally, the mesh generation equation was used. Determine the unit dimensions to complete model building, where, The distance to the structural surface, Distance to the monitoring point This refers to the distance to the tunnel construction area.

6. The method for evaluating the stress and deformation of existing subway structures under near-construction of urban tunnels according to claim 1, characterized in that, The objective function in S2 is specifically: The objective function, centered on the dynamic coupling between real-time monitoring data and numerical model prediction results, is defined as the cumulative spatial difference between the measured values ​​and calculated values ​​of physical quantities at monitoring points. The formula is as follows: ， in, The vector of formation parameters to be inverted; , The first and second marks are respectively the first and second marks. monitoring points Measured displacement and stress; , For three-dimensional geological-structural numerical models in terms of parameters The calculated value below; , These represent the maximum allowable displacement and stress of the structure corresponding to the monitoring point.

7. The method for evaluating the stress and deformation of existing subway structures under near-construction of urban tunnels according to claim 1, characterized in that, The stress-deformation prediction model in S3 is specifically as follows: The stress-deformation prediction model is based on the coupling relationship between the three-dimensional geological-structural numerical model and the dynamic characteristics of the construction stage. It establishes a prediction equation with the principle of virtual work as its core, and the expression is: ， The left side represents the virtual work done by the internal forces of the structure and strata. For stress tensor, For the strain tensor, ":" represents the tensor double dot product; the first term on the right represents the virtual work done by the volume forces. The vector of volumetric forces equal to the self-weight of the strata. It is a displacement vector. The second term represents the virtual work done by the boundary forces during tunnel construction. for The defined construction area boundary, The boundary force vector varies with the construction stage, and is related to the construction stage variables. Association satisfies , For the maximum construction boundary force, for The maximum design value; The displacement field can be obtained by solving this equation. Furthermore, through geometric equations Obtain the strain field, It is a symmetric gradient operator; combined with constitutive relations Obtain the stress field. This is the formation stiffness matrix obtained through inversion.

8. The method for evaluating the stress and deformation of existing subway structures under near-construction of urban tunnels according to claim 7, characterized in that, The specific method for solving the stress and deformation values ​​of existing subway structures at different construction stages in S3 is as follows: Define construction phase variables The boundary force vector of tunnel construction is expressed as , For the maximum construction boundary force, for Substituting the design maximum value into the virtual work equation, we get: ， in, This represents the construction boundary of stage S. The stress tensor containing stage variables, and the inverted formation parameters Through constitutive relations Related; For the existing subway structure area, the equations are discretized using the Galerkin weighted residual method, resulting in a matrix form: ， in, The overall stiffness matrix includes stage variables. For stage load vectors, The displacement vector of the structural nodes; Solving the equation yields The displacement values ​​of the marked monitoring points are extracted using an interpolation algorithm. , To monitor the shape function vector of the point; then use the stress recovery formula Calculate the force value , This is the strain-displacement transformation matrix for the monitoring point.

9. A stress and deformation assessment system for existing subway structures under near-construction of urban tunnels, characterized in that, include: The three-dimensional basic database construction unit is used to collect the geological physical and mechanical parameters of the urban tunnel near the construction impact zone, the existing subway structure design parameters, and the key parameters of tunnel construction; the geological physical and mechanical parameters are divided into geological zones and parameter intervals are marked according to the preset disturbance level; the key monitoring point information of the existing subway structure design parameters is marked; the construction stage division standard of the key parameters of tunnel construction is defined according to the construction method; and the above data are integrated to form a three-dimensional basic database. The stratigraphic parameter inversion and update unit is used to deploy equipment at key structural monitoring points to collect real-time monitoring data and preprocess it. Based on the three-dimensional basic database, a three-dimensional geological-structural numerical model is built. The inversion algorithm is constructed and the model is trained using the preprocessed data as the objective function. Real-time stratigraphic parameters are dynamically inverted and updated to the database. The structural stress and deformation prediction unit is used to construct a corresponding stress and deformation prediction model based on the type of nearby construction and real-time stratum parameters. It inputs real-time stratum parameters and key tunnel construction parameters to solve the stress and deformation values ​​of the existing subway structure at different construction stages. The early warning and model optimization unit is used to set early warning thresholds and build risk early warning models based on the existing subway structure safety level and related technical specifications. It compares the stress deformation value, deformation rate and early warning threshold to output the early warning level, calculates the model error periodically, and supplements samples to retrain the relevant model to achieve dynamic iterative optimization if the error exceeds the preset range.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, The computer program is executed by a processor according to any one of claims 1-8, which describes a method for evaluating the stress and deformation of existing subway structures under near-construction of urban tunnels.

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