Steel-concrete composite support active regulation and turnover evaluation method and system

Abstract

The application discloses a kind of steel-concrete combined support active regulation and turnover evaluation method and system, it is related to geotechnical engineering deep foundation pit support and monitoring technical field.The method includes two big technical schemes: one, the equivalent time-varying parameter of combined support is determined, the real-time monitoring data of combined support is obtained, then the temperature action component in monitoring total axial force, time effect component is calculated, finally the real stress response is calculated and combined support is actively regulated;Second, based on the strain history of the whole service process, plastic damage component, fatigue damage component and time-varying stiffness damage component are calculated respectively, and a comprehensive damage index is constructed by weighted summation.According to the preset grading threshold, the component disposal suggestion is output.The application can effectively eliminate the interference of temperature fluctuation and time-varying effect on regulation decision, and provide objective quantitative damage evaluation basis for component turnover use.The application can realize the whole life management of combined support, and improve the safety and economy of component turnover use.

Description

Technical Field

[0001] This invention belongs to the field of deep foundation pit support and monitoring technology in geotechnical engineering, specifically involving a method and system for active control and turnover assessment of steel-concrete composite support. Background Technology

[0002] In the construction of complex underground structures, precast steel-concrete composite supports have been increasingly applied to engineering scenarios such as large-span foundation pits, renovation of existing basements, and pipe jacking starting shafts due to their advantages such as high load-bearing capacity, high stiffness, fast construction speed, and reusability. Steel-concrete composite supports refer to support components formed by the joint stress of steel and concrete components, including but not limited to steel-concrete composite supports, steel-concrete composite supports, steel box-concrete composite supports, and the above-mentioned types of composite supports assembled from precast segments.

[0003] In existing technologies, the control of support systems is typically based primarily on the total axial force obtained from on-site monitoring. However, for steel-concrete composite supports, the total axial force monitored on-site is not entirely equivalent to the actual stress response caused by deformation of the retaining structure or changes in earth pressure. Steel-concrete composite supports are highly sensitive to changes in ambient temperature. In open or semi-open large-span foundation pit construction environments, factors such as diurnal temperature differences, solar radiation, and early-age temperature evolution of concrete can all cause significant fluctuations in the support axial force. In existing projects, servo control systems mostly use the monitored total axial force directly as the control basis, without further distinguishing between the actual stress components caused by deformation of the retaining structure and changes in earth pressure, and the additional components caused by temperature changes and time effects. This may lead the control system to overestimate the actual stress requirements of the support during temperature rises, and cause deviations between the support axial force and the target control value during temperature drops, thus affecting the accuracy of support stress regulation and the effectiveness of retaining structure deformation control.

[0004] Furthermore, steel-concrete composite supports are expensive and often require reuse in engineering projects. Current turnover management relies heavily on experience-based judgment, visual inspection, or simple static load checks, which fail to reflect the internal performance degradation caused by repeated temperature changes, long-term compression, and localized plastic development during the component's service life. Especially for components where concrete is encased in steel or subjected to combined stresses, internal microcracks, stiffness degradation, and cumulative damage are difficult to identify visually. The lack of a quantitative assessment method that combines actual stress history and time effects results in unreliable data for component reuse decisions. Summary of the Invention

[0005] To address the problem of poor accuracy in controlling the support force of steel-concrete composite supports in existing technologies, this invention provides a method and system for active control and turnover evaluation of steel-concrete composite supports, in order to solve the above-mentioned problems.

[0006] To solve the above technical problems, the present invention includes the following technical solutions:

[0007] A method for active control of steel-concrete composite supports includes:

[0008] Obtain the material and section parameters of the steel-concrete composite support, and determine the equivalent axial stiffness and equivalent linear expansion coefficient of the composite support;

[0009] Real-time acquisition of information on total axial force, average temperature, strain history, and service time of the combined support;

[0010] The temperature increment is determined based on the difference between the real-time temperature of the composite support and the initial reference temperature after installation. The temperature component is then calculated based on the equivalent axial stiffness and equivalent linear expansion coefficient of the composite support. :

[0011] Determine the time effect component based on the initial axial force and the concrete creep influence function. ;

[0012] Determine the true force response ,based on Actively adjust the combined support, among which, In the formula, To monitor the total axial force of the combined support, These are the on-site calibration coefficients.

[0013] Furthermore, the equivalent axial stiffness of the composite support section is: ,in,

[0014] ;

[0015] In the formula, For a moment Equivalent axial stiffness of the combined support; The elastic modulus of steel; The effective cross-sectional area of ​​the steel component; This is the reduction factor for the time-varying effects of concrete. The elastic modulus of concrete; This represents the effective cross-sectional area of ​​the concrete.

[0016] Furthermore, the equivalent linear expansion coefficient of the composite support composite section is: ,in,

[0017] ;

[0018] In the formula, For a moment The equivalent linear expansion coefficient of the combined support; The coefficient of linear expansion of steel; This is the coefficient of linear expansion of concrete.

[0019] Furthermore, the temperature increment determined by the difference between the real-time temperature of the combined support and the initial reference temperature during installation is: ;

[0020] Temperature component for:

[0021] ;

[0022] In the formula, This is the temperature constraint correction factor. .

[0023] Furthermore, the time-effect component for:

[0024] ;

[0025] In the formula, This is a time-effect correction factor; Initial axial force for installation; Let be the influence function of concrete creep, representing the time from the initial moment. At that time The degree of time-varying influence.

[0026] Furthermore, a threshold for the change in the actual force response is set. ,when When it is determined that a substantial change has occurred in the deformation of the retaining structure or the earth pressure, requiring adjustment, Nr(t) is used as the basis for active adjustment of the combined support to maintain the combined support in the target stress state; where, The time interval between two consecutive calculations is denoted as .

[0027] Furthermore, the present invention also provides a method for evaluating the turnover of steel-concrete composite supports, comprising the following steps:

[0028] The strain history of the combined support in the active control method of steel-concrete composite support during the entire service process is obtained by the sensor, the characteristic strain corresponding to the combined support entering the yield or nonlinear damage initiation state and the characteristic strain corresponding to the ultimate damage state are determined, and the plastic damage component is calculated based on the maximum master strain during the entire service process.

[0029] The strain history is statistically analyzed for stress amplitude, and fatigue damage components are calculated based on the actual number of cycles and the allowable number of cycles corresponding to each stress amplitude.

[0030] The time-varying stiffness damage component is calculated based on the equivalent axial stiffness at the initial moment of installation of the combined support and the equivalent axial stiffness at the end of service.

[0031] The plastic damage component, fatigue damage component, and time-varying stiffness damage component are weighted and summed to construct a comprehensive damage index.

[0032] Based on preset grading thresholds, the comprehensive damage index is graded and judged, and combined support treatment suggestions are output.

[0033] Furthermore, the plastic damage component is ,satisfy:

[0034] ;

[0035] when At that time, take ;when At that time, take ;

[0036] In the formula, To support the maximum master strain recorded throughout this service; The characteristic strain corresponding to the combined support entering the yield or nonlinear damage initiation state; The characteristic strain corresponding to the ultimate damage state of the combined support;

[0037] Fatigue damage component ,satisfy:

[0038] ;

[0039] In the formula, This represents the fatigue damage component; For the first The actual number of cycles corresponding to the stress amplitude; For the first The allowable number of cycles for a component to reach fatigue failure under a given stress amplitude; This represents the total number of stress amplitude classifications.

[0040] The time-varying stiffness damage component is ,satisfy:

[0041] ;

[0042] In the formula, This refers to the time-varying stiffness damage component; This marks the end of this service period. The equivalent axial stiffness; At the initial installation time The equivalent axial stiffness;

[0043] The overall damage index is D, which satisfies:

[0044] ;in, ;

[0045] In the formula, This is the plastic damage weighting coefficient; This is the fatigue damage weighting coefficient; This is the time-varying stiffness damage weighting coefficient.

[0046] This invention also provides an active control and turnover assessment system for steel-concrete composite supports, comprising:

[0047] The receiving unit is used to acquire the material parameters and cross-sectional parameters of the steel-concrete composite support; The sensing unit is used to collect information on the total axial force, average temperature, strain history, and service time of the steel-concrete composite support.

[0048] An execution unit is disposed at the end or connection node of the combined support, and is used to perform compensatory loading or unloading on the combined support according to the control command; The control unit, electrically connected to the sensing unit and the execution unit, incorporates a decoupling identification algorithm and a damage assessment model. The control unit periodically receives monitoring data collected by the sensing unit. The decoupling identification algorithm, based on the acquired material and cross-sectional parameters, determines the equivalent axial stiffness and equivalent linear expansion coefficient of the combined support, and calculates the temperature component based on the equivalent axial stiffness and equivalent linear expansion coefficient of the combined support. The time effect component was determined based on the initial axial force and the influence function of concrete creep. It can also calculate the actual force response. ,in, In the formula, To monitor the total axial force of the combined support, For on-site calibration coefficients; the control unit can also be based on Output control commands to the execution unit; the damage assessment model can calculate comprehensive damage indicators and output health assessment results;

[0049] The information management unit, connected to the control unit, is used to manage the component identification number, service record, damage index and treatment suggestions in the database, and generate a component life-cycle information identifier.

[0050] Furthermore, the sensing unit includes a distributed optical fiber sensor embedded inside the combined support, an inclination and temperature sensor disposed on the surface of the combined support, and an axial force gauge disposed at the end of the combined support.

[0051] The present invention, by employing the above technical solutions, has the following advantages and positive effects compared with existing technologies: The active control method for steel-concrete composite supports provided by the present invention can subtract the temperature component and the time effect component from the monitored total axial force to obtain the true stress response reflecting the deformation of the retaining structure and changes in earth pressure. Using this true stress response as the basis for active control, it effectively eliminates the interference of temperature fluctuations and concrete time-varying effects on control decisions, avoids the deviation caused by simply controlling based on the monitored total axial force, makes the active control actions more targeted, reduces unnecessary loading or unloading operations, and helps maintain the stability of the support's stress state and improve the deformation control effect of the retaining structure. The steel-concrete composite support turnover assessment method provided by the present invention connects damage accumulation assessment with the true stress response. Utilizing the strain, stress, temperature, and time history of the support throughout its service life, it calculates plastic damage, fatigue damage, and time-varying stiffness damage respectively, forming a comprehensive damage index. This method can more objectively reflect the health status of the composite support after its current service, providing a quantitative basis for component turnover, repair, and scrapping decisions. This invention comprehensively considers the active control and turnover assessment of combined supports, and incorporates the stress control during construction and the evaluation of components after service into the same technical framework. The front-end decoupled identification results directly serve the back-end damage assessment, forming an integrated method system with continuous data and logical closed loop. This is conducive to realizing the whole life management of steel-concrete composite supports and improving the safety and economy of component turnover. Attached Figure Description

[0052] Figure 1 This is a schematic diagram illustrating an application scenario of the steel-concrete composite support in one embodiment of the present invention;

[0053] Figure 2 This is a schematic diagram of the steel-concrete composite support and monitoring sensor arrangement in one embodiment of the present invention;

[0054] Figure 3 This is a flowchart of an active control method for steel-concrete composite support provided in an embodiment of the present invention.

[0055] The numbers in the diagram are as follows:

[0056] 1- Existing building and its foundation; 2- Foundation pit retaining structure; 3- Steel-concrete composite support main body; 3a- Steel pipe shell; 3b- Core concrete; 4- Adjustable lattice column support system; 5- End active control device; 6- Distributed and point sensor group; 7- Data transmission cable; 8- Central control station; 9- Embedded distributed fiber optic sensor; 10- Surface mounted MEMS tilt and temperature sensor unit; 11- Flange connection node. Detailed Implementation

[0057] The following detailed description, in conjunction with the accompanying drawings and specific embodiments, further illustrates the active control and turnover assessment method and system for steel-concrete composite supports provided by the present invention. The advantages and features of the present invention will become clearer from the following description. It should be noted that the accompanying drawings are all in a very simplified form and use non-precise scales, and are only used to facilitate and clarify the illustration of the embodiments of the present invention.

[0058] The overall concept of this invention is further described below. This invention addresses the core issue that "monitored total axial force is not equal to the actual control axial force," and constructs an integrated methodology system of "thermal-mechanical-time decoupled identification—active control—damage accumulation assessment." Its core inventive points include two aspects: First, it establishes a decoupled identification method for monitoring the total axial force of steel-concrete composite supports. By introducing equivalent parameters of the composite section, a temperature effect calculation model, and a time effect correction model, the monitored total axial force is decomposed into actual stress response components, temperature effect components, and time effect components, thereby obtaining a target control quantity that better reflects the deformation of the retaining structure and changes in earth pressure. Second, this invention establishes a damage accumulation assessment method that connects with the aforementioned actual stress response. Using the strain, stress, temperature, and time history of the support throughout its service life, it calculates plastic damage, fatigue damage, and time-varying stiffness damage respectively, forming a comprehensive damage index, based on which recommendations for component turnover, repair, or scrapping are given.

[0059] Combination Figure 1 and Figure 2 As shown, Figure 1 This demonstrates the application scenarios of the active control and turnover evaluation system for steel-concrete composite supports. Figure 2 The cross-sectional structure of the steel-concrete composite support is shown. This system is applied in foundation pit engineering. The existing building and its foundation 1 are located outside the foundation pit retaining structure 2. The steel-concrete composite support main body 3 is supported inside the foundation pit by an adjustable lattice column support system 4. Active control devices 5 are installed at both ends of the steel-concrete composite support main body 3 between it and the retaining structure 2. Distributed and point-type sensor groups 6 are connected to a central control station 8 via data transmission cables 7. The steel-concrete composite support main body 3 includes a steel pipe shell 3a and a core concrete 3b. Pre-embedded distributed fiber optic sensors 9 are embedded inside the core concrete 3b along the support length. Surface-mounted MEMS tilt and temperature sensor units 10 are installed on the surface of the steel pipe shell 3a. The segments are connected by flange connection nodes 11. This system can achieve real-time monitoring and active control of the support axial force, temperature, and strain.

[0060] Example 1

[0061] The present invention provides an active control method for steel-concrete composite supports, comprising the following steps:

[0062] Step S1: Obtain the material and section parameters of the steel-concrete composite support, and determine the equivalent time-varying parameters of the composite support. The equivalent time-varying parameters include the equivalent axial stiffness of the composite section of the composite support. and equivalent linear expansion coefficient .

[0063] Determining the equivalent time-varying parameters of steel-concrete composite supports specifically includes:

[0064] S11. Obtain combined support at the initial installation moment Basic parameters include: steel elastic modulus , elastic modulus of concrete cross-sectional area of ​​steel components Effective cross-sectional area of ​​concrete Coefficient of linear expansion of steel Coefficient of linear expansion of concrete Initial installation temperature Initial axial force .

[0065] S12. Determine the time-varying effect reduction factor of concrete based on the stress characteristics of the combined support. This reduction factor characterizes the reduction in equivalent stiffness of concrete due to creep, shrinkage, and long-term service. Its value is a function of time t and satisfies the following condition: By introducing a time-varying effect reduction factor, the mechanical properties of steel-concrete composite sections at different service stages are accurately characterized, providing a basis for the precise calculation of subsequent temperature and time effect components.

[0066] S13. Determine the equivalent axial stiffness of the combined section of the composite support. :

[0067] ;

[0068] In the formula, For a moment Equivalent axial stiffness of the combined support; The elastic modulus of steel; The effective cross-sectional area of ​​the steel component; This is the reduction factor for the time-varying effects of concrete. The elastic modulus of concrete; This represents the effective cross-sectional area of ​​the concrete.

[0069] S14. Determine the equivalent linear expansion coefficient of the composite section of the composite support. :

[0070] ;

[0071] In the formula, For a moment The equivalent linear expansion coefficient of the combined support; The coefficient of linear expansion of steel; This is the coefficient of linear expansion of concrete.

[0072] Step S2: Obtain real-time monitoring data of the combined support, including the total axial force of the support monitoring. Support average temperature Supporting the response process And supporting service time information .

[0073] Among them, the average temperature of support It can be obtained by combining distributed fiber optic temperature measurement systems, embedded temperature sensors, or surface temperature sensors; supporting the monitoring of total axial force. This information can be obtained through axial force gauges, strain inversion, or other existing and mature monitoring methods. (Refer to...) Figure 2 The average support temperature T(t) is obtained by combining the pre-embedded distributed fiber optic sensor 9 and the surface-mounted MEMS tilt and temperature sensor unit 10. The total axial force Nm(t) is obtained by the axial force gauge located at the end active control device 5. The support strain history ε(t) is obtained by the pre-embedded distributed fiber optic sensor 9, and the support service time information t is recorded simultaneously. The distributed fiber optic sensor can obtain the temperature and strain distribution along the length of the support, and the monitoring data covers the entire cross-section, with high spatial resolution and reliability.

[0074] Step S3: Calculate the temperature component in the total axial force monitored. .

[0075] First, determine the temperature increment based on the difference between the real-time temperature and the initial installation temperature. :

[0076] ;

[0077] Then, based on the equivalent axial stiffness and equivalent linear expansion coefficient of the combined support, the temperature component is calculated. :

[0078] ;

[0079] In the formula, For a moment The axial force component affected by temperature; This is a temperature constraint correction factor, used to characterize the influence of on-site boundary constraints, component installation status, and temperature distribution non-uniformity on temperature-related internal forces. ; For a moment The temperature difference relative to the initial installation temperature. This formula combines the equivalent thermodynamic parameters of the combined section with the measured temperature increment to achieve quantitative separation of temperature-induced axial force, eliminating the interference of factors such as diurnal temperature difference, solar radiation, and early-age temperature evolution of concrete on the monitoring of total axial force.

[0080] Step S4: Calculate the time effect component .

[0081] Considering the adjustment of internal forces caused by long-term time-varying effects such as concrete creep, a time-effect component is established. :

[0082] ;

[0083] In the formula, For a moment Time-effect axial force components; This is a time-effect correction factor, used to characterize the combined influence of concrete creep, shrinkage, and constraint conditions on the evolution of axial force in composite supports; Initial axial force for installation; Let be the influence function of concrete creep, representing the time from the initial moment. At that time The degree of time-varying influence. The axial force can be determined using existing concrete creep theoretical models or by forming an empirical function through on-site calibration. This step separates the additional axial force component caused by long-term time-varying effects such as concrete creep and shrinkage from the total monitored axial force.

[0084] Step S5: Calculate the actual force response ,based on Actively adjust the combined support.

[0085] The time is obtained by monitoring the total axial force, temperature component, and time effect component. Real force response :

[0086] ;

[0087] In the formula, For a moment The actual force response; These are the field calibration coefficients, used to correct for monitoring errors, model idealization errors, and individual differences in engineering projects; To monitor total axial force; This is the component that affects temperature; The time-effect component is used. Nr(t) serves as the sole control basis for the servo hydraulic actuator in the end-effector active control device 5, driving it to compensate for the load or unload the support axial force, maintaining the support in the target stress state. When the total axial force change is primarily due to temperature or time effects, the active control action is either not triggered or triggered less frequently, thus avoiding false or missed triggers and improving the deformation control effect of the enclosure structure. The aforementioned control commands are sent from the central control station 8 via data transmission cable 7, achieving automatic closed-loop control.

[0088] Furthermore, a threshold for the change in the actual force response is set. When the following expression is satisfied, it is determined that a substantial change has occurred in the deformation of the retaining structure or the earth pressure, requiring adjustment. Nr(t) is used as the basis for active adjustment of the combined support to maintain the combined support in the target stress state. The expression is:

[0089] ;

[0090] In the formula, The threshold value for the change in force response; The time interval between two consecutive calculations is denoted as .

[0091] When the actual force response exceeds the predetermined control range, the control system drives the servo hydraulic actuator to compensate for the load or unload the support axial force so that the support is maintained in the target force state; when the total axial force change is mainly due to temperature or time effects, the active control action is not triggered or is triggered less frequently.

[0092] Example 2

[0093] This embodiment provides a method for evaluating the turnover of steel-concrete composite supports, including the following steps:

[0094] Step S6: Based on the actual force response Damage assessment parameters, including plastic damage components Fatigue damage component Time-varying stiffness damage component .

[0095] Throughout the entire service life of the combined support, the strain history of the support is continuously recorded by pre-embedded distributed optical fiber sensors 9. and temperature history, combined with actual force response N r (t) constitutes complete service history data. The characteristic strain ε corresponding to the combined support entering the yielding or nonlinear damage initiation state is determined through finite element simulation or experiment. y And the characteristic strain ε corresponding to reaching the ultimate damage state. u According to the response process To obtain the maximum master strain ε of the combined support throughout the entire service process. max .

[0096] Throughout the entire service life of the combined support, the strain history of the support is continuously recorded by pre-embedded distributed optical fiber sensors 9. The temperature history, combined with the actual stress response Nr(t), constitutes a complete service history data. Through finite element simulation or experiments, the characteristic strain corresponding to the combined support entering the yielding or nonlinear damage initiation state can be obtained. Characteristic strain corresponding to the ultimate damage state of the combined support According to the response process To obtain the maximum control strain of the combined support throughout the entire service process. .

[0097] Plastic damage component for:

[0098] ;

[0099] when At that time, take ;when At that time, take .

[0100] In the formula, This refers to the maximum controlling strain recorded during the entire service life of the component; The characteristic strain corresponding to the component entering the yield or nonlinear damage initiation state; The characteristic strain corresponding to the ultimate damage state of the component.

[0101] Fatigue damage component for:

[0102] ;

[0103] In the formula, This represents the fatigue damage component; For the first The actual number of cycles corresponding to the stress amplitude; For the first The allowable number of cycles for a component to reach fatigue failure under a given stress amplitude; This represents the total number of stress amplitude grades. Stress amplitude is a key parameter describing the intensity of stress change in a material under cyclic loading, defined as half the difference between the maximum and minimum stress, and used to assess the fatigue life of a material. The stress amplitude grades are calculated using this formula. This formula quantitatively characterizes the degree of cumulative fatigue damage to a component under repeated loading by statistically analyzing the stress amplitude over the strain history ε(t) throughout its service life.

[0104] Time-varying stiffness damage component for:

[0105] ;

[0106] In the formula, This refers to the time-varying stiffness damage component; This marks the end of this service period. The equivalent axial stiffness; At the initial installation time The equivalent axial stiffness.

[0107] Step S7: Calculate the comprehensive damage index D and output turnover recommendations.

[0108] Based on each damage component, a comprehensive damage index D is constructed:

[0109] ;

[0110] And satisfy:

[0111] ;

[0112] In the formula, This is the plastic damage weighting coefficient; This is the fatigue damage weighting coefficient; This is the time-varying stiffness damage weighting coefficient.

[0113] For steel-concrete composite supports, it is preferable to use The value is the maximum of the three, to highlight the dominant influence of extreme strain and local nonlinear development on the residual load-bearing capacity of the component.

[0114] Based on comprehensive damage indicators Suggestions for component handling: When When the component is deemed to be in excellent condition, it can be directly reused; when When a component is deemed to be in a state of concern, further non-destructive testing, partial repair, or downgrading of its use should be performed; when At that time, it was determined that the component was no longer suitable for reuse as a main support. and The threshold for damage assessment grading, and satisfying .

[0115] Furthermore, the identification number, service time, monitoring data, and comprehensive damage index of each composite support will be included. The corresponding disposal suggestions are associated and stored, and a full life-cycle information identifier for the components is generated for subsequent site allocation and turnover management.

[0116] Example 3

[0117] This invention provides an active control and turnover assessment system for steel-concrete composite supports, comprising a receiving unit, a sensing unit, an execution unit, a control unit, and an information management unit.

[0118] The receiving unit can acquire the material and cross-sectional parameters of the steel-concrete composite support, such as allowing users to input data through an input interface.

[0119] The sensing unit is used to collect information on the total axial force, average temperature, strain history, and service life of the steel-concrete composite support. Combined with... Figure 1 and Figure 2 As shown, the sensing unit includes a pre-embedded distributed fiber optic sensor 9 embedded inside the core concrete 3b, a surface-mounted MEMS tilt and temperature sensor unit 10 installed on the surface of the steel pipe shell 3a, and an axial force gauge installed at the end active control device 5. Each sensor transmits monitoring data to the central control station 8 via a data transmission cable 7, enabling comprehensive real-time monitoring of the support status.

[0120] The execution unit is a servo hydraulic actuator located at the support end or connection node, used to perform compensated loading or unloading based on the actual force response. Figure 1 and Figure 2 As shown, the execution unit is an end active control device 5, which is set at the connection node between the end of the combined support body 3 and the foundation pit retaining structure 2. It includes a servo hydraulic actuator, which is used to compensate for the axial force of the combined support by loading or unloading according to the control command issued by the control unit, so as to realize precise active intervention in the stress state of the support.

[0121] The control unit is an industrial computer or embedded controller, which incorporates the decoupling identification algorithm described in this invention and the damage assessment model described in Embodiment 2. The control unit periodically receives monitoring data collected by the sensing unit. The decoupling identification algorithm, based on the acquired material and cross-sectional parameters, determines the equivalent axial stiffness and equivalent linear expansion coefficient of the combined support, and calculates the temperature component based on the equivalent axial stiffness and equivalent linear expansion coefficient of the combined support. The time effect component was determined based on the initial axial force and the influence function of concrete creep. It can also calculate the actual force response. ,in, In the formula, To monitor the total axial force of the combined support, For on-site calibration coefficients; the control unit can also be based on The control unit outputs control commands to the execution unit; the damage assessment model can calculate the comprehensive damage index and output the health assessment result, corresponding to steps 6 and 7 in Embodiment 2. The control unit also has a built-in control criterion, namely the threshold value ΔNth for the change in the actual force response, when |N...r (t)-N r (t-Δt)|≥ΔN th The system outputs control commands to drive the execution unit's actions.

[0122] The information management unit is connected to the control unit and integrated into the central control station 8. It is used to manage the database of component identification number, service record, damage index and treatment suggestions. It can also generate QR codes or electronic tags to bind to the component entity, forming a full life-cycle information identification for the component, so as to facilitate subsequent site allocation and turnover management.

[0123] The aforementioned system organically integrates four functional units: sensing, execution, control, and information management. It achieves integrated operation of proactive control during construction and damage assessment after service, which is conducive to the full life-cycle management of steel-concrete composite supports.

[0124] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0125] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. A method for active control of steel-concrete composite supports, characterized in that, include: Obtain the material and section parameters of the steel-concrete composite support, and determine the equivalent axial stiffness and equivalent linear expansion coefficient of the composite support; Real-time acquisition of information on total axial force, average temperature, strain history, and service time of the combined support; The temperature increment is determined based on the difference between the real-time temperature of the composite support and the initial reference temperature after installation. The temperature component is then calculated based on the equivalent axial stiffness and equivalent linear expansion coefficient of the composite support. : Determine the time effect component based on the initial axial force and the concrete creep influence function. ; Determine the true force response ,based on Actively adjust the combined support, among which, In the formula, To monitor the total axial force of the combined support, These are the on-site calibration coefficients.

2. The active control method for steel-concrete composite supports as described in claim 1, characterized in that, The equivalent axial stiffness of the composite support section is ,in, ； In the formula, For a moment Equivalent axial stiffness of the combined support; The elastic modulus of steel; The effective cross-sectional area of ​​the steel component; This is the reduction factor for the time-varying effects of concrete. The elastic modulus of concrete; This represents the effective cross-sectional area of ​​the concrete.

3. The active control method for steel-concrete composite supports as described in claim 1, characterized in that, The equivalent linear expansion coefficient of the composite support composite section is ,in, ； In the formula, For a moment The equivalent linear expansion coefficient of the combined support; The coefficient of linear expansion of steel; This is the coefficient of linear expansion of concrete.

4. The active control method for steel-concrete composite supports as described in claim 1, characterized in that, The temperature increment is determined by the difference between the real-time temperature of the combined support and the initial reference temperature during installation. ; Temperature component for: ； In the formula, This is the temperature constraint correction factor. .

5. The active control method for steel-concrete composite supports as described in claim 1, characterized in that, Time-effect component for: ； In the formula, This is a time-effect correction factor; Initial axial force for installation; Let be the influence function of concrete creep, representing the time from the initial moment. At that time The degree of time-varying influence.

6. The active control method for steel-concrete composite supports as described in claim 1, characterized in that, Set the threshold for changes in the actual force response ,when When it is determined that a substantial change has occurred in the deformation of the retaining structure or the earth pressure, requiring adjustment, Nr(t) is used as the basis for active adjustment of the combined support to maintain the combined support in the target stress state; where, The time interval between two consecutive calculations is denoted as .

7. A method for evaluating the turnover of steel-concrete composite supports, characterized in that, The strain history of the combined support in the active control method of steel-concrete composite support according to any one of claims 1 to 6 is obtained by the sensor during the entire service process. The characteristic strain corresponding to the combined support entering the yield or nonlinear damage initiation state and the characteristic strain corresponding to reaching the ultimate damage state are determined. The plastic damage component is calculated based on the maximum master control strain during the entire service process. The strain history is statistically analyzed for stress amplitude, and fatigue damage components are calculated based on the actual number of cycles and the allowable number of cycles corresponding to each stress amplitude. The time-varying stiffness damage component is calculated based on the equivalent axial stiffness at the initial moment of installation of the combined support and the equivalent axial stiffness at the end of service. The plastic damage component, fatigue damage component, and time-varying stiffness damage component are weighted and summed to construct a comprehensive damage index. Based on preset grading thresholds, the comprehensive damage index is graded and judged, and combined support treatment suggestions are output.

8. The method for evaluating the turnover of steel-concrete composite supports as described in claim 7, characterized in that, The plastic damage component is ,satisfy: ； when At that time, take ;when At that time, take ; In the formula, To support the maximum master strain recorded throughout this service; The characteristic strain corresponding to the combined support entering the yield or nonlinear damage initiation state; The characteristic strain corresponding to the ultimate damage state of the combined support; Fatigue damage component ,satisfy: ； In the formula, This represents the fatigue damage component; For the first The actual number of cycles corresponding to the stress amplitude; For the first The allowable number of cycles for a component to reach fatigue failure under a given stress amplitude; This represents the total number of stress amplitude classifications. The time-varying stiffness damage component is ,satisfy: ； In the formula, This represents the time-varying stiffness damage component; This marks the end of this service period. The equivalent axial stiffness; For the initial installation time The equivalent axial stiffness; The overall damage index is D, which satisfies: ;in, ; In the formula, This is the plastic damage weighting coefficient; This is the fatigue damage weighting coefficient; This is the time-varying stiffness damage weighting coefficient.

9. A steel-concrete composite support active control and turnover evaluation system, characterized in that, include: The receiving unit is used to acquire the material parameters and cross-sectional parameters of the steel-concrete composite support; The sensing unit is used to collect information on the total axial force, average temperature, strain history, and service time of the steel-concrete composite support. An execution unit is disposed at the end or connection node of the combined support, and is used to perform compensatory loading or unloading on the combined support according to the control command; The control unit, electrically connected to the sensing unit and the execution unit, incorporates a decoupling identification algorithm and a damage assessment model. The control unit periodically receives monitoring data collected by the sensing unit. The decoupling identification algorithm, based on the acquired material and cross-sectional parameters, determines the equivalent axial stiffness and equivalent linear expansion coefficient of the combined support, and calculates the temperature component based on the equivalent axial stiffness and equivalent linear expansion coefficient of the combined support. The time effect component was determined based on the initial axial force and the influence function of concrete creep. It can also calculate the actual force response. ,in, In the formula, To monitor the total axial force of the combined support, For on-site calibration coefficients; the control unit can also be based on Output control commands to the execution unit; the damage assessment model can calculate comprehensive damage indicators and output health assessment results; The information management unit, connected to the control unit, is used to manage the component identification number, service record, damage index and treatment suggestions in the database, and generate a component life-cycle information identifier.

10. The active control and turnover evaluation system for steel-concrete composite supports as described in claim 9, characterized in that, The sensing unit includes a distributed optical fiber sensor embedded inside the combined support, an inclination and temperature sensor disposed on the surface of the combined support, and an axial force gauge disposed at the end of the combined support.

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