Digital twinning construction method for linear elastic stress field of concrete structure foundation constraint area

Abstract

A concrete structure foundation constraint area linear elastic stress field digital twinning construction method comprises the steps that non-stress strain needing to be compensated for stress adjustment of a strong constraint area is calculated according to actually measured stress, and then a concrete structure foundation constraint area linear elastic stress field is constructed. The calculation precision of the linear elastic stress field of the strong constraint area can be greatly improved by embedding a small number of stress monitoring probes in the concrete structure constraint area, and the stress field is converged to a true value along with the increase of the number of measuring points. The method comprises the following steps: (1) obtaining a strain adjustment direction and a stress meter embedding position; (2) calculating a node non-stress strain adjustment amount; (3) calculating the unit non-stress strain adjustment amount; and (4) executing finite element calculation.

Description

Technical Field

[0001] The present invention belongs to the technical field of intersection of artificial intelligence and numerical analysis of large-volume concrete, and in particular relates to a method for constructing a digital twin of a linear elastic stress field in a constraint zone of a concrete structure foundation. Background Art

[0002] In finite element calculation, it is very important to adjust the finite element calculation results by monitoring the numerical values. For example, in the calculation of the temperature field of large-volume concrete, due to the common errors between the concrete material parameters and the actual parameters, it is necessary to correct the temperature field through the monitoring results of the temperature measurement points to obtain accurate calculation results. Similarly, in the calculation of the stress field of large-volume concrete, the calculation parameters required to accurately calculate the elastic stress of concrete include temperature deformation, bulk density, elastic modulus, linear expansion coefficient, autogenous volume deformation, creep deformation, etc. There may also be large errors in the calculation process, but there is no result of constructing the stress field of large-volume concrete through the results of large-volume concrete stress monitoring. The main reasons are as follows:

[0003] (1) Previous stress monitoring technologies have difficulty in accurately calculating stress. Previous stress monitoring technologies measure the strain of concrete structures through strain gauges, and then calculate the stress of concrete structures based on the measured strain of concrete structures. Multiple mechanical parameters are required for calculation, and their values ​​are difficult to grasp, resulting in inaccurate stress calculation results, and sometimes even distorted stress laws of concrete structures.

[0004] (2) In the past, the construction of "field" based on measuring points was mainly achieved through interpolation methods or the method of modifying finite element parameters. Although the interpolation method can ensure that there is no error at the measuring point, the various "field" distributions in reality often cannot be expressed as simple functions, so the construction of stress field by interpolation is not accurate. When using finite element calculation and analysis, even if there is monitoring data, the number of parameters to be adjusted is large. Since some parameter models have many constants, the concrete parameters in different regions may be different. When dealing with multi-parameter conditions, manual optimization algorithms and artificial intelligence machine learning models are prone to local solutions rather than global solutions. For a series of reasons, it is currently difficult to obtain the "field" by adjusting the finite element calculation parameters using manual or machine learning methods.

[0005] In terms of direct stress monitoring, great progress has been made. The name of the patent application is: Dynamometer based on magnetic grid displacement meter and method for monitoring concrete stress (application number CN202310581285.1), which provides a dynamometer based on a magnetic field displacement meter, and a monitoring structure and method for large-volume concrete stress constructed using the dynamometer. This patent application measures the deformation of the center points of the top and bottom surfaces of the force measuring block by a magnetic field displacement meter, and calculates the stress value of the concrete being measured. The concrete stress value monitored by the monitoring structure and method provided by this patent application is close to the true stress value of the concrete, providing real and reliable stress data support for the safe operation status of large-volume concrete structures. At the same time, the stress monitoring area is not necessarily the area with the greatest stress. Obtaining an accurate stress field on the basis of accurate stress is still the most effective way to ensure structural safety.

[0006] The patent application is titled: Method for constructing temperature field of digital twin of mass concrete (application number CN202410505018.0), which provides a method to automatically adjust the finite element calculation results according to the temperature data of the measuring points acquired in real time. This method can accurately construct the temperature field, and the calculated value and measured value of the measuring point temperature of the constructed temperature field completely coincide with each other, and the error is controlled within the range of any set value, which provides an accurate temperature field for the accurate construction of the stress field, and also provides a direction for the construction of the stress field. However, there is a big difference between the temperature field and the stress field, and there is currently no accurate method for constructing the stress field.

[0007] It is generally believed that the constraint of non-stress deformation of concrete is the reason for stress and cracking in the concrete constraint zone. Unlike surface cracks in concrete, cracks in the foundation constraint zone of concrete are difficult to detect and difficult to repair. Therefore, it is crucial to accurately calculate the stress in the concrete constraint zone and propose reasonable temperature control measures for dam safety. At the same time, the advancement of existing technologies has provided a basis for the digital construction of the linear elastic stress field in the foundation constraint zone of concrete structures, but a reasonable construction method has not yet been proposed. Summary of the invention

[0008] In order to overcome the defects of the prior art, the technical problem to be solved by the present invention is to provide a digital twin construction method of the linear elastic stress field in the constraint area of ​​the concrete structure foundation, which can greatly improve the calculation accuracy of the linear elastic stress field in the strong constraint area by burying a small number of stress monitoring probes in the constraint area of ​​the concrete structure. As the number of measuring points increases, the stress field converges to the true value.

[0009] The technical solution of the present invention is: a method for constructing a digital twin of a linear elastic stress field in a foundation constraint zone of a concrete structure, comprising the following steps:

[0010] (1) Obtain the strain adjustment direction and the buried position of the stress gauge:

[0011] Take 1 unit of autogenous volume deformation to calculate the stress of the concrete structure, and obtain the stress in the x, y and z directions in the finite element mesh. Calculate the ratio of stress to autogenous volume deformation shrinkage in the x, y and z directions, which is recorded as con x 、con y and con z , if the h direction satisfies:

[0012] con h =max(con x ,con y ,con z ) (2)

[0013] Then h is the non-stress strain adjustment direction, con h is the constraint degree of the point; several stress measuring points are buried in the constraint area of ​​the concrete structure, one of which is buried in the area with the maximum constraint degree;

[0014] (2) Calculate the node non-stress strain adjustment: The calculation is divided into steps in the time domain, and iterative calculation is performed in each step. In the nth step, the error between the calculated stress value and the measured value at the end of the jth iteration calculation is calculated. If the error is less than the allowable error, the calculation is stopped and the n+1th step is performed. If the error is greater than the allowable error, the strain {Δε inj}:

[0015] {Δε inj =D e ] -1 {Δσ inj} (3)

[0016] Among them, [D e ] is the elastic matrix, and the non-stress strain is continuously adjusted during the iteration process to correct the stress field. inj} is the stress calculated after the jth iteration of the nth period at the measuring point i; the node non-stress strain adjustment is determined according to the cause of the structural stress error;

[0017] (3) Calculation of unit non-stress strain adjustment: When the number of measurement points is limited, assume that there are g measurement points in the fth bin, and arrange the temperature change amplitudes of the measurement points in the nth time period from small to large. When performing the nth step calculation, if the temperature change amplitude of the Gaussian point is between the temperature change amplitudes of measurement points 1 and g, and the constraint degree of the Gaussian point is between the constraint degrees of measurement points mi and mi+k, and the constraint values ​​of measurement points mi and mi+k are adjacent, then the non-stress strain adjustment of the Gaussian integral point is for:

[0018]

[0019] Where n represents the nth time period, f represents the fth bin, q represents the qth unit, r represents the rth Gaussian integration point of the qth unit, ΔT mi Indicates the temperature variation of the mi-th measuring point in the n-th calculation step, ΔT mi+k Indicates the temperature variation of the mi+kth measurement point in the nth calculation step, ΔT qr It represents the temperature variation of the rth Gaussian integration point of the qth unit in the nth calculation step; It represents the non-stress strain adjustment of the mi+kth measuring point in the j+1th iteration calculation of the nth calculation step; It represents the non-stress strain adjustment of the mi-th measuring point in the j+1-th iteration calculation of the n-th calculation step; is the non-stress strain adjustment calculated at the j+1th iteration of the nth time period, the fth bin, the qth unit, and the rth Gaussian integration point;

[0020] If the temperature of the Gauss point is less than the temperature variation of the measuring point 1 or exceeds the temperature variation of the measuring point g, or the constraint degree of the Gauss point is greater than the minimum constraint degree of the measuring point or exceeds the maximum constraint degree of the measuring point, then:

[0021] ΔT 1 -k(ΔT g -ΔT 1 )<ΔT qr <ΔT g +k(ΔT g -ΔT 1 ) (5)

[0022] Where, ΔT 1 It represents the temperature variation of the first measuring point in the fth bin in the nth calculation step, ΔT 1 represents the temperature variation of the gth measuring point in the fth bin in the nth calculation step, k is a constant,

[0023]

[0024] Where, ΔT max is the maximum temperature variation of the stress adjustment area in the nth calculation period, ΔT min is the minimum value of the temperature change amplitude in the stress adjustment area during the nth calculation period; for the Gaussian points that satisfy equations (5) and (6), if the constraint degrees of the measuring points mi and mi+k are adjacent, and the constraint degree of the Gaussian point is between the constraint degrees of the measuring points mi and mi+k, then the measuring points mi, mi+k, and equation (4) are selected for calculation; if the constraint degree of the Gaussian point is outside the measuring point range, then the measuring points mi and mi+k are the two points with the closest constraint degrees of the Gaussian point, and are calculated according to equation (4) at the same time;

[0025] (4) Finite element calculation method performed during the iteration process:

[0026] ∫∫{B} T [D]{B}dxdydzδ e =∫∫{B} T [D]{Δε n,j}dxdydz+{F} e (9)

[0027] When j ≥ 2, according to the basic principle of finite element analysis, the left side of equation (9) integrates the overall stiffness matrix of the structure, and the right side integrates the load matrix. Considering the constraints of the nodes and the absence of external loads during the iteration process, the node displacement δ of the unit is solved. e .

[0028] The present invention meets the requirement of digital twin definition of "realizing the mapping of virtual and real from the real to the real by truly replicating the physical entity into the digital space", adjusts the unit node force error, obtains the strain adjustment direction and the buried position of the stress gauge, calculates the node non-stress strain adjustment amount, calculates the unit non-stress strain adjustment amount, and then performs finite element calculation. Therefore, a small number of stress monitoring probes can be buried in the constraint area of ​​the concrete structure to greatly improve the calculation accuracy of the linear elastic stress field in the strong constraint area. As the number of measuring points increases, the stress field converges to the true value. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The present invention is a flowchart of the method for constructing a digital twin of the linear elastic stress field in the foundation constraint area of ​​a concrete structure according to the present invention. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0031] In order to make the description of the present disclosure more detailed and complete, the following provides an illustrative description of the implementation and specific embodiments of the present invention; however, this is not the only form of implementing or using the specific embodiments of the present invention. The implementation covers the features of multiple specific embodiments and the method steps and sequences used to construct and operate these specific embodiments. However, other specific embodiments can also be used to achieve the same or equivalent functions and step sequences.

[0032] The present invention calculates the non-stress strain that needs to be compensated for the stress adjustment in the strong constraint area based on the actual measured stress, and then constructs the linear elastic stress field in the constraint area of ​​the concrete structure foundation. Unit node force of the linear elastic stress field finite element:

[0033] {F} e =∫∫{B}T [D]{ε e}dxdydz (1)

[0034] Among them, {F} e is the nodal force of the elastic stress field finite element, {B} T is the shape matrix, which is only related to the shape of the unit, [D] is the elasticity matrix, {ε e} is stress and strain.

[0035] Since the basic principle of linear elastic stress field is that the resultant force of the node load is balanced with the external load, applying accurate node load force can replace the unit to participate in finite element calculation. Similarly, during the calculation process, if there is an error between the node force of some structures and the true value, the finite element calculation results can be corrected by adjusting the node force.

[0036] The linear elastic stress field error of the constraint zone of the concrete structure foundation includes: external load error, mechanical parameter (mainly elastic modulus) error, non-stress strain calculation error, etc. If the stress is in the constraint zone of the structure, the stress converted by the constraint is proportional to the stress. The present invention calculates the non-stress strain that needs to be "compensated" for adjusting the stress in the strong constraint zone based on the actual measured stress, and then accurately constructs the linear elastic stress field of the constraint zone of the concrete foundation.

[0037] Since the non-stress strain has little effect on the stress in the unconstrained area, extending the "compensated" non-stress strain in the constrained area to the entire area can significantly improve the calculation accuracy of the constrained area without having a significant impact on the stress in the unconstrained area.

[0038] like Figure 1 As shown, the method for constructing a digital twin of the linear elastic stress field in the constraint zone of the concrete structure foundation includes the following steps:

[0039] (1) Obtain the strain adjustment direction and the buried position of the stress gauge:

[0040] Take 1 unit of autogenous volume deformation to calculate the stress of the concrete structure, and obtain the stress in the x, y and z directions in the finite element mesh. Calculate the ratio of stress to autogenous volume deformation shrinkage in the x, y and z directions, which is recorded as con x 、con y and con z , if the h direction satisfies:

[0041] con h =max(con x ,con y ,con z ) (2)

[0042] Then h is the non-stress strain adjustment direction, conh is the constraint degree of the point; several stress measuring points are buried in the constraint area of ​​the concrete structure, one of which is buried in the area with the maximum constraint degree;

[0043] (2) Calculate the node non-stress strain adjustment: The calculation is divided into steps in the time domain, and iterative calculation is performed in each step. In the nth step, the error between the calculated stress value and the measured value at the end of the jth iteration calculation is calculated. If the error is less than the allowable error, the calculation is stopped and the n+1th step is performed. If the error is greater than the allowable error, the strain {Δε inj}:

[0044] {Δε inj =D e ] -1 {Δσ inj} (3)

[0045] Among them, [D e ] is the elastic matrix, and the non-stress strain is continuously adjusted during the iteration process to correct the stress field. inj} is the stress calculated after the jth iteration of the nth period at the measuring point i; the node non-stress strain adjustment is determined according to the cause of the structural stress error;

[0046] (3) Calculation of unit non-stress strain adjustment: When the number of measurement points is limited, assume that there are g measurement points in the fth bin, and arrange the temperature change amplitudes of the measurement points in the nth time period from small to large. When performing the nth step calculation, if the temperature change amplitude of the Gaussian point is between the temperature change amplitudes of measurement points 1 and g, and the constraint degree of the Gaussian point is between the constraint degrees of measurement points mi and mi+k, and the constraint values ​​of measurement points mi and mi+k are adjacent, then the non-stress strain adjustment of the Gaussian integral point is for:

[0047]

[0048] Where n represents the nth time period, f represents the fth bin, q represents the qth unit, r represents the rth Gaussian integration point of the qth unit, ΔT mi Indicates the temperature variation of the mi-th measuring point in the n-th calculation step, ΔT mi+k Indicates the temperature variation of the mi+kth measurement point in the nth calculation step, ΔT qr It represents the temperature variation of the rth Gaussian integration point of the qth unit in the nth calculation step; It represents the non-stress strain adjustment of the mi+kth measuring point in the j+1th iteration calculation of the nth calculation step; It represents the non-stress strain adjustment of the mi-th measuring point in the j+1-th iteration calculation of the n-th calculation step; is the non-stress strain adjustment calculated at the j+1th iteration of the nth time period, the fth bin, the qth unit, and the rth Gaussian integration point;

[0049] If the temperature of the Gauss point is less than the temperature variation of the measuring point 1 or exceeds the temperature variation of the measuring point g, or the constraint degree of the Gauss point is greater than the minimum constraint degree of the measuring point or exceeds the maximum constraint degree of the measuring point, then:

[0050] ΔT 1 -k(ΔT g -ΔT 1 )<ΔT qr <ΔT g +k(ΔT g -ΔT 1 ) (5)

[0051] Where, ΔT 1 It represents the temperature variation of the first measuring point in the fth bin in the nth calculation step, ΔT 1 represents the temperature variation of the gth measuring point in the fth bin in the nth calculation step, k is a constant,

[0052]

[0053] Where, ΔT max is the maximum temperature variation of the stress adjustment area in the nth calculation period, ΔT min is the minimum value of the temperature change amplitude in the stress adjustment area during the nth calculation period; for the Gaussian points that satisfy equations (5) and (6), if the constraint degrees of the measuring points mi and mi+k are adjacent, and the constraint degree of the Gaussian point is between the constraint degrees of the measuring points mi and mi+k, then the measuring points mi, mi+k, and equation (4) are selected for calculation; if the constraint degree of the Gaussian point is outside the measuring point range, then the measuring points mi and mi+k are the two points with the closest constraint degrees of the Gaussian point, and are calculated according to equation (4) at the same time;

[0054] (4) Finite element calculation method performed during the iteration process:

[0055] Considering the constrained non-stress strain forming stress deformation, the nodal force of the element is:

[0056] {F} e =∫∫{B} T [D]{ε n,j+1 -Δε n,j}dxdydz (7)

[0057] Among them, ε n,j is the total strain formed in the j+1th iteration of the nth step, Δε n,j is the non-stress strain applied at the j+1th iteration of the nth step.

[0058] According to the basic principles of finite element analysis:

[0059] ε n,j+1 ={B}δ e (8)

[0060] Among them, δ e is the nodal displacement of the element.

[0061] From formula (7) and formula (8), we can know that:

[0062] ∫∫{B} T [D]{B}dxdydzδ e =∫∫{B} T [D]{Δε n,j}dxdydz+{F} e (9)

[0063] Where j ≥ 2. According to the basic principle of finite element analysis, the left side of equation (9) integrates the overall stiffness matrix of the structure, and the right side integrates the load matrix. Considering the constraints of the nodes and the absence of external loads during the iteration process, the node displacement δ of the unit is solved. e .

[0064] The present invention meets the requirement of digital twin definition of "realizing the mapping of virtual and real from the real to the real by truly replicating the physical entity into the digital space", adjusts the unit node force error, obtains the strain adjustment direction and the buried position of the stress gauge, calculates the node non-stress strain adjustment amount, calculates the unit non-stress strain adjustment amount, and then performs finite element calculation. Therefore, a small number of stress monitoring probes can be buried in the constraint area of ​​the concrete structure to greatly improve the calculation accuracy of the linear elastic stress field in the strong constraint area. As the number of measuring points increases, the stress field converges to the true value.

[0065] When the number of measuring points is insufficient, interpolation using nodes with similar properties to the unit can quickly increase the convergence accuracy. The stress of mass concrete mainly includes two parts: stress generated by load and stress generated by non-stress deformation constraint. Structural loads, such as water load and self-weight load, can be accurately taken. The factor affecting the calculation of the linear elastic stress field in the constraint area of ​​the concrete structure foundation is the stress generated by non-stress deformation constraint. The stress generated by non-stress deformation constraint includes: stress generated by temperature deformation constraint, stress generated by self-volume deformation constraint and stress constrained by creep load. Self-volume deformation is a constant, temperature deformation load is a function linearly related to temperature, and creep load is a function positively related to temperature and constraint degree. When interpolating, partitioning is performed according to the constraint degree, and considering the characteristics of temperature and self-generated volume deformation, a high-precision stress field can be constructed with a small number of stress measuring points.

[0066] Preferably, in step (2), the error between the calculated stress value and the measured value at the end of the j-th iteration calculation at the measuring point i in the n-th period is:

[0067] {Δσ inj}={σ in}-{σ inj} (10)

[0068] Among them, {σ in} is the stress at the measuring point i at the end of the nth period, {Δσ inj} is the stress calculated at the measuring point i after the jth iteration of the nth period;

[0069] Calculate the error between the calculated stress value and the measured value at the end of the jth iteration:

[0070]

[0071] Where g is the total number of monitoring points.

[0072] Preferably, in step (2), if the error is caused only by spontaneous volume deformation and temperature deformation, the non-stress strain adjustment amount applied in step j+1 is:

[0073]

[0074] Among them, h is one of the x, y, and z directions in the finite element calculation model, and the determination method is formula (2).

[0075] Preferably, in step (2), if the structural stress error is caused by other non-negligible errors besides the autogenous volume deformation and temperature deformation calculation errors, the node non-stress strain adjustment amount is:

[0076]

[0077] Preferably, in step (3), if there are many measuring points in the structure, the following interpolation method is used to obtain the non-stress strain adjustment of the Gaussian points inside the unit:

[0078]

[0079] Among them, mi represents the number of stress measuring points in bin f, g represents the number of temperature measuring points in bin f, represents the non-stress strain adjustment amount applied at the j+1th step at the mith measuring point in the nth period, q represents the qth unit, r represents the rth Gaussian integration point of the qth unit, d mi It represents the distance from the mi-th measuring point to the r-th integration point of the q-th unit. s is a constant and is negative.

[0080] Preferably, in step (3), when ΔT mi+k and ΔT mi Too close, the iterative calculation is divergent. Within the constraint area, the non-stress strain adjustment of the element is:

[0081]

[0082] Among them, con mi,h represents the constraint degree of the mi-th measuring point, con mi+k,h represents the constraint degree of the mi+kth measurement point, con qr,h Represents the constraint degree of the rth Gaussian integration point of the qth element.

[0083] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the protection scope of the technical solution of the present invention.

Claims

1. A digital twin construction method for linear elastic stress field in the constraint zone of a concrete structure foundation, characterized by: It includes the following steps: (1) Obtain the strain adjustment direction and the buried position of the stress gauge: Take 1 unit of autogenous volume deformation to calculate the stress of the concrete structure, and obtain the stress in the x, y and z directions in the finite element mesh. Calculate the ratio of stress to autogenous volume deformation shrinkage in the x, y and z directions, which is recorded as con x 、con y and con z , if the h direction satisfies: with h =max(with x ,with y ,with z ) (2) Then h is the non-stress strain adjustment direction, con h is the constraint degree of the point; several stress measuring points are buried in the constraint area of ​​the concrete structure, one of which is buried in the area with the maximum constraint degree; (2) Calculate the node non-stress strain adjustment: The calculation is divided into steps in the time domain, and iterative calculation is performed in each step. In the nth step, the error between the calculated stress value and the measured value at the end of the jth iteration calculation is calculated. If the error is less than the allowable error, the calculation is stopped and the n+1th step is performed. If the error is greater than the allowable error, the strain {Δε inj }: {In j }=[D e ] -1 {Ds inj } (3) Among them, [D e ] is the elastic matrix, and the non-stress strain is continuously adjusted during the iteration process to correct the stress field. inj } is the stress calculated after the jth iteration of the nth period at the measuring point i; the node non-stress strain adjustment is determined according to the cause of the structural stress error; (3) Calculation of unit non-stress strain adjustment: When the number of measurement points is limited, assume that there are g measurement points in the fth bin, and arrange the temperature change amplitudes of the measurement points in the nth time period from small to large. When performing the nth step calculation, if the temperature change amplitude of the Gaussian point is between the temperature change amplitudes of measurement points 1 and g, and the constraint degree of the Gaussian point is between the constraint degrees of measurement points mi and mi+k, and the constraint values ​​of measurement points mi and mi+k are adjacent, then the non-stress strain adjustment of the Gaussian integral point is for: Where n represents the nth time period, f represents the fth bin, q represents the qth unit, r represents the rth Gaussian integration point of the qth unit, ΔT mi Indicates the temperature variation of the mi-th measuring point in the n-th calculation step, ΔT mi+k Indicates the temperature variation of the mi+kth measurement point in the nth calculation step, ΔT qr It represents the temperature variation of the rth Gaussian integration point of the qth unit in the nth calculation step; It represents the non-stress strain adjustment of the mi+kth measuring point in the j+1th iteration calculation of the nth calculation step; It represents the non-stress strain adjustment of the mi-th measuring point in the j+1-th iteration calculation of the n-th calculation step; is the non-stress strain adjustment calculated at the j+1th iteration of the nth time period, the fth bin, the qth unit, and the rth Gaussian integration point; If the temperature of the Gauss point is less than the temperature variation of the measuring point 1 or exceeds the temperature variation of the measuring point g, or the constraint degree of the Gauss point is greater than the minimum constraint degree of the measuring point or exceeds the maximum constraint degree of the measuring point, then: ΔT1-k(ΔT g -ΔT1)<ΔT qr <ΔT g +k(△T g -△T1) (5) Among them, ΔT1 represents the temperature variation of the first measuring point in the fth bin in the nth calculation step, ΔT1 represents the temperature variation of the gth measuring point in the fth bin in the nth calculation step, k is a constant, Among them, △T max is the maximum temperature variation of the stress adjustment area in the nth calculation period, ΔT min is the minimum value of the temperature change amplitude in the stress adjustment area during the nth calculation period; for the Gaussian points that satisfy equations (5) and (6), if the constraint degrees of the measuring points mi and mi+k are adjacent, and the constraint degree of the Gaussian point is between the constraint degrees of the measuring points mi and mi+k, then the measuring points mi, mi+k, and equation (4) are selected for calculation; if the constraint degree of the Gaussian point is outside the measuring point range, then the measuring points mi and mi+k are the two points with the closest constraint degrees of the Gaussian point, and are calculated according to equation (4) at the same time; (4) Finite element calculation method performed during the iteration process: ∫∫{B} T [D]{B}dxdydzδ e =∫∫{B} T [D]{No n，j }dxdydz+{F} e (9) When j ≥ 2, according to the basic principle of finite element analysis, the left side of equation (9) integrates the overall stiffness matrix of the structure, and the right side integrates the load matrix. Considering the constraints of the nodes and the absence of external loads during the iteration process, the node displacement δ of the unit is solved. e .

2. The method for constructing a digital twin of a linear elastic stress field in a foundation constraint zone of a concrete structure according to claim 1, characterized in that: In step (2), the error between the calculated stress value and the measured value at the end of the j-th iteration calculation at the measuring point i in the n-th period is: {Ds inj }={σ in }-{s inj } (10) Among them, {σ in } is the stress at the measuring point i at the end of the nth period, {Δσ inj } is the stress calculated after the nth iteration of measuring point i; Calculate the error between the calculated stress value and the measured value at the end of the ,th iteration: Where g is the total number of monitoring points.

3. The method for constructing a digital twin of a linear elastic stress field in a foundation constraint zone of a concrete structure according to claim 2, characterized in that: In step (2), if the error is caused only by spontaneous volume deformation and temperature deformation, the non-stress strain adjustment amount applied in step j+1 is: Among them, h is one of the x, y, and z directions in the finite element calculation model, and the determination method is formula (2).

4. The method for constructing a digital twin of a linear elastic stress field in a foundation constraint zone of a concrete structure according to claim 2, characterized in that: In step (2), if the structural stress error is caused by other non-negligible errors besides the autogenous volume deformation and temperature deformation calculation errors, the node non-stress strain adjustment is:

5. The method for constructing a digital twin of a linear elastic stress field in a foundation constraint zone of a concrete structure according to claim 4, characterized in that: In step (3), if there are many measuring points in the structure, the following interpolation method is used to obtain the non-stress strain adjustment of the Gaussian points inside the unit: Among them, mi represents the number of stress measuring points in bin f, g represents the number of temperature measuring points in bin f, represents the non-stress strain adjustment amount applied at the j+1th step at the mith measuring point in the nth period, q represents the qth unit, r represents the rth Gaussian integration point of the qth unit, d mi It represents the distance from the mi-th measuring point to the r-th integration point of the q-th unit, D= s is a constant and is negative.

6. The method for constructing a digital twin of a linear elastic stress field in a foundation constraint zone of a concrete structure according to claim 4, characterized in that: In step (3), when ΔT mi+k and ΔT mi Too close, the iterative calculation is divergent. Within the constraint area, the non-stress strain adjustment of the element is: Among them, con mi，h represents the constraint degree of the mi-th measuring point, con mi+k，h represents the constraint degree of the mi+kth measurement point, con qr，h Represents the constraint degree of the rth Gaussian integration point of the qth element.

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