Methods, systems, equipment and media for construction safety assessment of shield tunnels

Abstract

This invention relates to the field of underground engineering technology and discloses a method, system, equipment, and medium for construction safety assessment of shield tunnels. The method quantifies the construction load and foundation coefficient in the current construction step and inputs them into a nonlinear mechanical solution framework composed of a longitudinal multi-ring model and a single-ring variable model. This process obtains the longitudinal deformation of each beam element. If the deformation does not meet preset requirements, the quantification process is repeated until the preset requirements are met. The bending and shear modes of each beam element are determined based on the single-ring variable model to assess the safety status of the current construction step. The current construction step is updated, and the assessment process for the safety status of the updated step is iteratively executed until all construction steps are completed, resulting in a safety assessment of the shield tunnel under construction loads. The method accurately solves for the nonlinear deformation response in the longitudinal direction of the shield tunnel and achieves a comprehensive and accurate safety assessment of the shield tunnel.

Description

Technical Field

[0001] This invention relates to the field of underground engineering technology, and in particular to a method, system, equipment and medium for construction safety assessment of shield tunnels. Background Technology

[0002] Because the construction of a shield tunnel is a dynamic process, a problem at any stage can prevent the next stage from proceeding. Therefore, assessing the safety status of the shield tunnel at each construction stage is crucial. Currently, longitudinal mechanical analysis models, such as the longitudinal beam-spring model and the longitudinal equivalent continuity model, are commonly used. These models simplify the shield tunnel and construct an equivalent model to quantify its longitudinal deformation. This is then combined with a risk index evaluation system or a construction parameter prediction model to assess the construction safety of the shield tunnel. However, these methods typically do not consider the stiffness variation characteristics of the shield tunnel, making it impossible to accurately solve for the longitudinal mechanical response, thus affecting the accuracy of the safety assessment of shield tunnel construction.

[0003] Therefore, how to solve the problem that existing technologies do not consider the stiffness variation characteristics of shield tunnels, thus making it impossible to accurately solve the longitudinal mechanical response and affecting the accuracy of the safety assessment of shield tunnel construction has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] This invention provides a method, system, equipment, and medium for construction safety assessment of shield tunnels, which solves the problem that traditional mechanical models fail to consider stiffness variation characteristics, thus making it impossible to accurately solve the longitudinal mechanical response and affecting the accuracy of construction safety assessment of shield tunnels.

[0005] To address the aforementioned technical problems, the first aspect of this invention provides a construction safety assessment method for shield tunnels, comprising:

[0006] In the current construction phase, the basic parameters of the shield tunnel are acquired in real time to quantify the construction load and foundation coefficient, and the shield tunnel is discretized into several beam units.

[0007] The construction load and the foundation coefficient are input into a longitudinal multi-ring model constructed based on each beam element, and the mechanical response data of each beam element are obtained by quantification using the transfer matrix method.

[0008] The mechanical response data of each of the above are input into the single-ring variable model processing, and the longitudinal deformation of each of the beam elements is output.

[0009] If the longitudinal deformation of each beam element does not meet the preset requirements, the quantification process of the longitudinal deformation of each beam element is repeated until the final longitudinal deformation meets the preset requirements. Based on the single-ring deformation model of the final repeated cycle, the bending mode and shear mode of each beam element are determined to evaluate the safety status of each beam element in the current construction step.

[0010] The current construction step is updated to iteratively perform the safety status assessment process of each beam unit in the updated current construction step until all construction steps are completed, so as to generate the safety assessment result of the shield tunnel under construction load.

[0011] A second aspect of the present invention provides a construction safety assessment system for shield tunnels, comprising:

[0012] The beam element discretization module is used to acquire the basic parameters of the shield tunnel in real time during the current construction step, so as to quantify the construction load and foundation coefficient, and discretize the shield tunnel into several beam elements.

[0013] The multi-ring scale quantization module is used to input the construction load and the foundation coefficient into the longitudinal multi-ring model constructed based on each beam element for processing, and to obtain the mechanical response data of each beam element by quantization through the transfer matrix method;

[0014] The single-ring scale quantization module is used to input the mechanical response data of each of the above into the single-ring variable model processing, and output the longitudinal deformation of each of the beam elements;

[0015] The first state evaluation module is used to repeatedly execute the quantification process of the longitudinal deformation of each beam unit if the longitudinal deformation of each beam unit does not meet the preset requirements, until the final longitudinal deformation meets the preset requirements, and determine the bending mode and shear mode of each beam unit based on the single-ring deformation model of the final repeated rounds, so as to evaluate the safety status of each beam unit in the current construction step.

[0016] The second state assessment module is used to update the current construction step to iteratively perform the assessment process of the safety status of each beam unit in the updated current construction step until all construction steps are completed, so as to generate the safety assessment result of the shield tunnel under construction load.

[0017] A third aspect of the present invention provides an electronic device including a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein the processor executes the computer program to implement the construction safety assessment method for shield tunnels as described above.

[0018] A fourth aspect of the present invention provides a computer-readable storage medium comprising a stored computer program, wherein when the device containing the computer-readable storage medium executes the computer program, it implements the construction safety assessment method for shield tunnels as described above.

[0019] Compared with the prior art, the beneficial effects of the embodiments of the present invention are as follows:

[0020] Precise quantification of key parameters provides an accurate data foundation for subsequent analysis, facilitating a more accurate assessment of the stress and foundation characteristics of the tunnel during construction and reducing assessment errors caused by inaccurate parameters. The quantified parameters are input into a nonlinear mechanical solution framework consisting of a longitudinal multi-ring model and a single-ring variable model to accurately solve for the nonlinear deformation response of the shield tunnel in the longitudinal direction. An iterative processing mechanism ensures that the deformation of the tunnel structure remains within a controllable range, effectively avoiding safety issues such as structural damage due to excessive deformation, and improving the safety and reliability of tunnel construction. By updating construction steps to track the stress and deformation of the tunnel structure in real time at different construction stages, the accuracy of safety assessment for shield tunnel construction is improved, providing comprehensive and continuous safety assurance for the entire construction process. Attached Figure Description

[0021] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a structural diagram of a longitudinal beam-spring model provided in a certain embodiment of the present invention;

[0023] Figure 2 This is a structural diagram of a longitudinal equivalent continuous model provided in a certain embodiment of the present invention;

[0024] Figure 3 This is a schematic diagram of a longitudinal mechanical model for simulating the construction stage using an equivalent continuous beam, provided in a certain embodiment of the present invention.

[0025] Figure 4 This is a flowchart of a construction safety assessment method for shield tunnels provided in a certain embodiment of the present invention;

[0026] Figure 5 This is a dynamic diagram of shield tunnel construction provided in a certain embodiment of the present invention;

[0027] Figure 6This is a structural diagram of a single elastic foundation beam unit provided in a certain embodiment of the present invention;

[0028] Figure 7 This is a front view along the tunnel axis provided in a certain embodiment of the present invention;

[0029] Figure 8 This is a side view along the tunnel axis provided in a certain embodiment of the present invention;

[0030] Figure 9 This is a flowchart of the process for quantifying the longitudinal deformation of a beam element according to a certain embodiment of the present invention;

[0031] Figure 10 This is a cumulative longitudinal deformation diagram provided in a certain embodiment of the present invention;

[0032] Figure 11 This is a security partition diagram provided in one embodiment of the present invention;

[0033] Figure 12 This is a structural diagram of a construction safety assessment system for shield tunnels provided in a certain embodiment of the present invention;

[0034] Figure 13 This is a structural diagram of an electronic device provided in a certain embodiment of the present invention;

[0035] Figure label:

[0036] Among them, 10 is the beam element discrete module; 20 is the multi-ring scale quantization module; 30 is the single-ring scale quantization module; 40 is the first state evaluation module; 50 is the second state evaluation module; 5000 is the electronic device; 5001 is the processor; 5002 is the bus; 5003 is the memory; and 5004 is the transceiver. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings and examples. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0038] In the description of this invention, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," "third," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0039] In the description of this invention, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to communication within two components. The terms "vertical," "horizontal," "left," "right," "upper," "lower," and similar expressions used herein are for illustrative purposes only and do not indicate or imply that the system or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0040] In the description of this invention, it should be noted that, unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this specification is merely for describing specific embodiments and is not intended to limit the invention. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0041] Shield tunnels are discontinuous structures longitudinally assembled from segment rings and bolts, resulting in numerous inter-ring joints. Under the combined action of multiple loads during construction, these joints are highly susceptible to significant deformation. Excessive longitudinal deformation can further induce engineering defects such as joint opening, segment misalignment, segment damage, and water leakage, seriously threatening the tunnel structure. Accurate prediction of longitudinal deformation in shield tunnels is crucial for preventing joint defects and ensuring tunnel structural safety. Currently, the commonly used longitudinal beam-spring model is as follows: Figure 1 As shown, it simplifies the tunnel structure into a series of beam elements, which are connected by springs to simulate the mechanical properties of joints; while the longitudinal equivalent continuous model structure is as follows: Figure 2 As shown, it simplifies the entire tunnel structure into a continuous beam, ignores the specific details of the joints, and reflects the influence of the joints on the overall mechanical behavior through equivalent parameters such as longitudinal equivalent bending stiffness and longitudinal equivalent shear stiffness.

[0042] A schematic diagram of the longitudinal mechanical model for simulating the construction stage using an equivalent continuous beam is shown below. Figure 3 As shown, shield tunnels mainly bear two types of external loads: additional bending moment and buoyancy. The former originates from uneven thrust of the jacks, while the latter comes from the synchronous grouting process. In this model, equivalent bending stiffness and equivalent shear stiffness are key parameters, and their values ​​directly affect the accuracy of deformation prediction and safety assessment. However, traditional longitudinal mechanical models in the construction stage often treat these two key parameters as fixed values, ignoring the nonlinear variation characteristics of stiffness. This leads to significant deviations between the calculated mechanical response and the actual situation. Therefore, when combining them with risk index evaluation systems or construction parameter prediction models to assess the construction safety of shield tunnels, it is impossible to accurately solve the longitudinal mechanical response, thus affecting the accuracy of the safety assessment of shield tunnel construction. In reality, the existence of joints causes their contact state and stress characteristics to change continuously, thus affecting the fluctuation of these two stiffness parameters. The contact state and stress characteristics are also affected by bending moment and shear force. Therefore, under the action of multi-source construction loads, the equivalent bending stiffness and equivalent shear stiffness of each ring segment in the longitudinal direction will fluctuate. Accurately determining the stiffness value of each unit is the key to ensuring the accuracy of the calculation.

[0043] Based on this, this invention divides the solution of longitudinal deformation of shield tunnels into two scales: overall multi-ring and local single-ring. From the overall multi-ring scale, longitudinal bending moment and shear force fluctuate; however, from the local single-ring scale, the equivalent bending stiffness and equivalent shear stiffness are affected by bending moment and shear force. Therefore, the overall multi-ring scale and the local single-ring scale influence each other. This invention integrates the overall multi-ring scale and the local single-ring scale, and based on the fixed-point iteration method, constructs a nonlinear mechanical solution framework consisting of a longitudinal multi-ring model and a single-ring variable model. This framework can accurately solve the longitudinal nonlinear mechanical response, thus enabling a comprehensive and accurate evaluation of tunnel safety without relying solely on standards that consider only the bending and shear nonlinear characteristics of the joints.

[0044] In one embodiment, such as Figure 4 As shown, the first aspect of the present invention provides a construction safety assessment method for shield tunnels, comprising:

[0045] S1. In the current construction step, the basic parameters of the shield tunnel are acquired in real time to quantify the construction load and foundation coefficient, and the shield tunnel is discretized into several beam units.

[0046] Because the construction of a shield tunnel is a dynamic process, as the tunnel boring machine advances one ring, the construction load moves forward one ring, and the range of change in the subgrade coefficient also moves forward one ring. This cycle repeats to simulate the continuous forward excavation process of the tunnel boring machine. A dynamic diagram of shield tunnel construction is shown below. Figure 5As shown, this invention selects the segment ring that exits the shield tail in the first construction step as the target ring for examination, and takes the construction step to which it belongs as the current construction step, in order to quantify the mechanical response of a single construction step of a shield tunnel.

[0047] This invention involves installing various sensors, such as displacement sensors, pressure sensors, strain sensors, and other measuring tools, at the shield tunnel construction site to acquire in real time data on the structural parameters (such as tunnel length and diameter), stratum parameters (such as stratum thickness), and construction parameters (such as jack thrust and synchronous grouting pressure) of the shield tunnel during the current construction step. The acquired data is then used as basic parameters to quantify the construction load and foundation coefficient of the current construction step.

[0048] In one embodiment, the construction load includes an additional vertical bending moment; wherein the additional vertical bending moment is calculated using the following formula:

[0049]

[0050] In the formula, M0 is the vertical additional bending moment; n is the number of jacks; P i y represents the thrust (kN) generated by the i-th jack group; i Let be the distance (m) between the i-th group of jacks and the horizontal centroidal axis; where the horizontal centroidal axis refers to the geometric center axis of the tunnel cross section in the horizontal direction, which can be calculated by integration or segmentation.

[0051] During tunnel boring machine (TBM) excavation, uneven distribution of jack thrust can cause additional bending moments in the tunnel structure. Failure to accurately calculate and consider this factor may underestimate the stress on the structure, thus failing to detect potential safety hazards in a timely manner. This invention calculates the additional vertical bending moment, which more accurately reflects the impact of construction on the tunnel structure, providing a reliable basis for subsequent safety assessments and structural design.

[0052] Construction loads also include buoyancy, which is the resultant force of multiple loads and is expressed by the following formula:

[0053] q0 = p sta -p gra -p gra '

[0054] p sta =γ j πR 2

[0055] In the formula, q0 is the buoyancy force; p sta p gra p gra’ These represent the self-weight per unit length of the tunnel segment (kN / m), the Archimedes buoyancy per unit length (kN / m), and the mechanical self-weight per unit length (kN / m); γj The specific gravity of the slurry (kN / m³) 3 R is the radius of the tunnel (m).

[0056] The subgrade coefficients include the subgrade reaction coefficient and the subgrade shear coefficient; the subgrade reaction coefficient is expressed by the following formula:

[0057]

[0058] In the formula, k is the foundation reaction coefficient; E0 is the equivalent deformation modulus of soil and grout (MPa); v is the Poisson's ratio of the soil; D c E is the diameter of the tunnel (m); 0b E represents the deformation modulus of the slurry layer (MPa). 0g H represents the formation elastic modulus (MPa). h The influence range of synchronous grouting (m); H b H represents the thickness of the slurry layer (m); g θ1 is the thickness (m) of the stratum within the grouting influence range; θ1 is the load distribution angle, usually assumed to be 30°.

[0059] The shear coefficient of the foundation is expressed by the following formula:

[0060]

[0061] In the formula, G t h is the shear coefficient of the foundation. t The thickness of the shear layer is (m); it should be noted that t in the formula has no meaning and is only used as a subscript to distinguish different physical quantities.

[0062] Next, the longitudinal mechanical model of the construction stage is discretized into Timoshenko beams on a two-parameter elastic foundation. That is, the longitudinal multi-ring shield tunnel is discretized into several beam units. Each beam unit is discretized into several independent beam units according to the segment rings. That is, each ring of segments corresponds to one beam unit, which is a complete ring of segments connected by bolts (including the segment body, the contact state of the ring joints, and shear-resistant components such as bolts and tenons). This allows the longitudinal deformation of each beam unit—equivalent bending stiffness and equivalent shear stiffness—to vary. Before iterative calculation, the equivalent bending and shear stiffness of all beam units are initialized to be equal to the bending and shear stiffness of the segment ring itself.

[0063] S2. Input the construction load and the foundation coefficient into the longitudinal multi-ring model constructed based on each beam element for processing, and quantify the mechanical response data of each beam element by means of the transfer matrix method;

[0064] In one embodiment, step S2 includes:

[0065] Based on Timoshenko beam theory, differential equations for each beam element are established and simplified into matrix form to obtain the mechanical model of each beam element, thereby constructing the longitudinal multi-ring model.

[0066] The longitudinal multi-ring model is subjected to Laplace transformation to obtain the initial parameter solution model, and the coupling stiffness index of each beam element is quantified to determine the target transfer matrix and its target load influence matrix of each beam element.

[0067] The construction load and the foundation coefficient are input into the longitudinal multi-ring model for processing, and combined with the target transfer matrix and the target load influence matrix, to transfer the load from the starting point to the end point of the shield tunnel, thereby obtaining the mechanical response data of each beam element.

[0068] Specifically, for a discrete single elastic foundation beam element, its structure is as follows: Figure 6 As shown, this invention establishes the differential equations of each beam element based on Timoshenko beam theory and simplifies them to matrix form, obtaining the mechanical model of each beam element. That is, the mechanical response variables of each beam element have the following relationship:

[0069]

[0070] In the formula, w is the deflection (mm); θ is the section rotation angle (rad); q is the shear angle (rad); M is the bending moment (kN·m); Q is the shear force (kN); D is the equivalent bending stiffness (kN·m / rad), which is the initial equivalent bending stiffness input during the first calculation; C is the equivalent shear stiffness (kN), which is also the initial equivalent shear stiffness input during the first calculation; B is the width of the beam element (m), which can be the diameter of the shield tunnel; q is the initial value of the load; m This represents the gradient of the load.

[0071] After simplification, the differential equation can be expressed as:

[0072]

[0073] In the formula, K is the first simplified parameter, which is the product of the foundation reaction coefficient and the width of the beam element; G is the second simplified parameter, which is the product of the foundation shear coefficient and the width of the beam element.

[0074] Based on the connection relationships between beam elements (such as hinged connections, rigid connections, etc.), the mechanical models of each beam element are combined to construct a longitudinal multi-ring model. This model describes the mechanical transmission relationship of the entire tunnel structure from the starting point to the ending point. A Laplace transform is then applied to it to obtain the initial parameter solution model, which is expressed by the following equation:

[0075] S = TS0 + F

[0076] S=[wθM Q] T

[0077] S0 = [w0θ0M0 Q0] T

[0078] In the formula, S is the initial parameter solution; T is the transfer matrix; F is the load influence matrix; and the subscripts indicate the initial positions, corresponding to... Figure 6 Point O on the left.

[0079] Next, the coupling stiffness index of each beam element is quantified based on the subgrade coefficient, thereby determining the target transfer matrix and its target load influence matrix for each beam element. Starting from the beginning of the shield tunnel, combining the target transfer matrix and target load influence matrix of each beam element, and following the principle of the transfer matrix method, the mechanical response data of each beam element is calculated sequentially. That is, the subgrade coefficient, construction load, and equivalent bending and shear stiffness data of each beam element are input into the corresponding mechanical models in the longitudinal multi-ring model to solve for the initial parameter solutions of each two-parameter elastic foundation beam element. By continuously transferring the calculations using the transfer matrix method until the end of the tunnel, the transfer matrices of all beam elements are combined to obtain the transfer matrix combination model, which can be expressed as:

[0080] S1=T1S0+F1

[0081] S2 = T2S1 + F2

[0082] …

[0083] S n =T n S n-1 +F n

[0084] In the formula, S0 and S1 are the mechanical response vectors of the left and right ends of the first beam element, respectively; S n T n and F n These are the mechanical response vector, transfer matrix, and load influence matrix at the right end of the nth beam element, respectively.

[0085] Since the transfer matrix and load influence matrix of each beam segment are only related to the equivalent bending stiffness, equivalent shear stiffness, and external load of the tunnel, inputting these influencing factors into the above transfer matrix combination model results in only the four response variables of S0 being unknowns. In the specific implementation of the transfer matrix method, the boundary conditions (see [reference]) are... Figure 1The problem is transformed into solving equations. Since there are two known conditions on the left and two on the right, and the whole system has 4n variables (4 for each element), 4n equations can be established through transitive relations. However, the problem is actually transformed into solving a 4×4 linear equation system by using the transitive matrix method (after having two known conditions on the left, there are two unknowns, and then two equations are established using the two conditions on the right). This allows us to obtain the mechanical response data (deflection, rotation, bending moment, and shear force) of each beam element at different positions in the longitudinal direction.

[0086] This invention transforms complex tunnel structure problems into a series of transfer relationships between beam elements by constructing a longitudinal multi-ring model and employing the transfer matrix method. This avoids large-scale numerical solutions for the entire tunnel structure, significantly reducing the computational load and improving computational efficiency. It can quickly obtain the mechanical response data of each beam element, facilitating real-time monitoring and analysis of the mechanical state during tunnel construction. By using construction load and foundation coefficient as input parameters, it fully considers the various external forces experienced by the shield tunnel during actual construction, more realistically reflecting the actual stress situation of the tunnel and providing a reliable basis for construction safety assessment and structural optimization.

[0087] In one embodiment, quantifying the coupling stiffness index of each beam element to determine the target transfer matrix and its target load influence matrix of each beam element includes:

[0088] The coupling stiffness index of each beam element is quantified based on the foundation coefficient.

[0089] When the coupling stiffness index is less than zero, the target transfer matrix and the target load influence matrix are constructed based on the foundation parameters, the construction load and the subgrade coefficient, and using trigonometric functions as matrix properties.

[0090] When the coupling stiffness index is equal to zero, the target transfer matrix and the target load influence matrix are constructed based on the foundation parameters, the construction load and the subgrade coefficient, and using the polynomial as the matrix property.

[0091] When the coupling stiffness index is greater than zero, the target transfer matrix and the target load influence matrix are constructed based on the foundation parameters, the construction load and the subgrade coefficient, and using the hyperbolic function as a matrix property.

[0092] Specifically, this invention quantifies the coupling stiffness index of each beam element based on the foundation coefficient. This index is a quantitative indicator of the interaction between the beam element's own stiffness and the foundation constraints. The longitudinal multi-ring model is essentially a differential equation of an elastic foundation beam. Its solution process requires analyzing the form of the solution through the characteristic equation. The coupling stiffness index is the discriminant of the characteristic equation, directly determining the type of characteristic roots, and thus affecting the functional form of the solution (the forms of the transfer matrix and load influence matrix must be consistent with the form of the solution). Therefore, the type of the characteristic equation roots determines the functional form of the solution of the differential equation (trigonometric function, linear function, hyperbolic function). The coupling stiffness index is expressed by the following formula:

[0093]

[0094] In the formula, Δ is the coupling stiffness index.

[0095] The transfer matrix describes the transfer relationship from the mechanical state at one end of a beam element to the mechanical state at the other end, and it is expressed by the following formula:

[0096]

[0097] The load influence matrix considers the impact of external loads on the mechanical state of the beam element, and is expressed by the following formula:

[0098] F = Fq + Fq m

[0099] Fq = [Fq1 Fq2 Fq3 Fq4] T

[0100] Fq m =[Fqm1 Fqm2 Fqm3 Fqm4] T

[0101] In the formula, Fq is the load initial value influence matrix; Fq m This is the load gradient influence matrix.

[0102] When the coupling stiffness index is less than zero, the eigenvalues ​​are conjugate complex numbers. The coupling between the foundation constraints and the beam element stiffness is more likely to induce oscillatory responses, and the solution involves trigonometric functions (sine and cosine). The transfer matrix and load influence matrix need to be constructed using trigonometric functions to describe the displacement and internal force transmission of the oscillations. Therefore, this invention, based on foundation parameters, construction loads, and foundation coefficients, uses trigonometric functions as matrix properties to construct the target transfer matrix and the target load influence matrix; wherein, each term in the target transfer matrix is ​​expressed by the following formula:

[0103]

[0104]

[0105] CS = cosh(Ax)sin(Bx)

[0106] SC = sinh(Ax)cos(Bx)

[0107] SS = sinh(Ax)sin(Bx)

[0108]

[0109] In the formula, A and B are the third and fourth simplification parameters, respectively; CC and SS are the first and second transfer coefficients, respectively; and SC and CS are the first and second cross-coupling coefficients, respectively.

[0110] The terms in the target load influence matrix are expressed by the following formula:

[0111]

[0112]

[0113] When the coupling stiffness index is zero, the eigenvalues ​​are all real roots. The coupling between the foundation constraint and the beam element stiffness exhibits a linear trend, and it is in a critical equilibrium state (the boundary between oscillation and attenuation). The solution contains linear terms, and the transfer matrix and load influence matrix need to be in linear function form to match the non-oscillating, linear transfer characteristics under the critical state. Therefore, this invention, based on foundation parameters, construction loads, and foundation coefficients, uses polynomials as matrix properties to construct the target transfer matrix and the target load influence matrix; wherein, each term in the target transfer matrix is ​​expressed by the following formula:

[0114]

[0115]

[0116] CA = cosh(Ax)

[0117] SA = sinh(Ax)

[0118] XCA = xcosh(Ax)

[0119] XSA = xsinh(Ax)

[0120]

[0121] In the formula, A is the fifth simplified parameter; CA and SA are the first and second oscillation coefficients, respectively; XCA and XSA are the first and second variation coefficients, respectively.

[0122] The terms in the target load influence matrix are expressed by the following formula:

[0123]

[0124] When the coupling stiffness index is greater than zero, the eigenvalues ​​are unequal real roots. Foundation constraints or beam stiffness are more likely to lead to monotonic decay / growth, requiring the solution to be in hyperbolic function form. The transfer matrix and load influence matrix need to be constructed using hyperbolic functions to describe the monotonic displacement and internal force transfer. Therefore, this invention, based on foundation parameters, construction loads, and subgrade coefficients, uses hyperbolic functions as matrix properties to construct the target transfer matrix and target load influence matrix; where each term in the target transfer matrix is ​​expressed by the following formula:

[0125]

[0126]

[0127] CA = cosh(Ax)

[0128] SA = sinh(Ax)

[0129] CB = cosh(Bx)

[0130] SB = sinh(Bx)

[0131]

[0132] In the formula, A and B are the sixth and seventh simplified parameters, respectively; CA and SA are the first and second bending response coefficients, respectively; and CB and SB are the first and second shear response coefficients, respectively.

[0133] The terms in the target load influence matrix are expressed by the following formula:

[0134]

[0135] This invention quantifies the coupling stiffness index of each beam element and constructs the target transfer matrix and target load influence matrix using different matrix properties based on their different value ranges. This allows for a more accurate reflection of the mechanical properties of the beam elements under different foundation conditions. Hyperbolic functions, polynomial functions, and trigonometric functions are used as matrix properties for three different cases: coupling stiffness index greater than zero, equal to zero, and less than zero, respectively. This enables the model to adapt to various complex foundation conditions and enhances its applicability in different engineering scenarios. By accurately calculating the target transfer matrix and target load influence matrix, the mechanical response of the beam elements can be obtained more precisely, thereby more accurately assessing the safety status of the tunnel structure at the current construction stage, promptly identifying potential safety hazards, and ensuring construction safety.

[0136] S3. Input the mechanical response data of each element into the single-ring variable model processing, and output the longitudinal deformation of each beam element; the single-ring variable model includes a single-ring bending model and a single-ring shear model; wherein...

[0137] In one embodiment, step S3 includes:

[0138] The mechanical response data are input into the single-ring bending model for processing, and the equivalent bending stiffness and neutral axis height of each beam element are output.

[0139] Based on the height of each neutral axis, the contact area of ​​the ring joints contained in each beam element is determined, and then input with the basic parameters into the single-ring shear model for processing, and the equivalent shear stiffness of each beam element is output.

[0140] The equivalent bending stiffness and equivalent shear stiffness of each beam element are output as the longitudinal deformation of each beam element.

[0141] Specifically, the mechanical response data of each beam element is input into a single-ring bending model for processing, and the equivalent bending stiffness, neutral axis height, joint rotation angle, and bolt stress of each beam element are output. The single-ring bending model adopts the patent application number CN202410249948.4, "A method and system for solving the longitudinal equivalent bending stiffness of shield tunnels". Since this processing is not an innovation in this invention, but only a reference, it will not be described in detail.

[0142] To maintain harmony between bending and shear deformation modes, the actual contact area and neutral axis height of the interlocking joints of each beam element are closely related, and are expressed by the following formula:

[0143]

[0144] In the formula, A s ' is the contact area; R0 is the radius of the tunnel's central circle (m); t is the thickness of the tunnel segment (m). The height of the neutral axis (m).

[0145] Finally, the calculated contact area and basic parameters are input into the single-ring shear model for processing, and the equivalent shear stiffness of each beam element is output. By combining this with the equivalent bending stiffness of each beam element, the longitudinal deformation of each beam element can be obtained.

[0146] This invention processes mechanical response data by inputting it into a single-ring bending model and a single-ring shear model, respectively, enabling in-depth analysis of the mechanical properties of beam elements from two key aspects: bending and shear. The separate model processing method comprehensively considers various mechanical properties of the tunnel structure, avoiding the neglect of certain important factors due to the simplification of a single model, thereby improving the accuracy of deformation calculation. It also considers the influence of bending and shear stiffness changes, thus accurately solving the nonlinear deformation response of the shield tunnel in the longitudinal direction.

[0147] In one embodiment, the single-ring shear model is composed of a first-stage model, a second-stage model, and a third-stage model; wherein,

[0148] The process of inputting the basic parameters into the single-ring shear model and outputting the equivalent shear stiffness of each beam element includes:

[0149] The shear force borne by each beam element and the axial force borne by each ring joint are obtained, and the friction force of each beam element is quantified according to the axial force for comparison with the shear force.

[0150] If each of the frictional forces is not less than each of the shear forces, then the basic parameters and each of the contact areas are input into the first stage model processing, and the equivalent shear stiffness of each of the beam elements is output.

[0151] If each of the frictional forces is less than each of the shear forces and the bolt shear stress obtained based on each of the shear forces is not greater than the preset shear stress, then the basic parameters and each of the contact areas are input into the second stage model processing, and the equivalent shear stiffness of each of the beam elements is output.

[0152] If the shear stress of each bolt is greater than the preset shear stress, then the basic parameters and the contact areas are input into the third-stage model processing to output the equivalent shear stiffness of each beam element.

[0153] Specifically, the front view and side view of the beam element along the tunnel axis are as follows: Figure 7 , 8 As shown, when a single-ring segment is simultaneously subjected to axial force and shear force, three shear forces resist shear deformation: the frictional force of the ring joint, and the shear force provided by the bolts and tenons. These three shear forces exert their effects in the following order: first, the frictional force, then the shear force from the bolts and tenons. Based on this order of shear force action, this invention divides the single-ring shear model into a first-stage model, a second-stage model, and a third-stage model.

[0154] Because the ring joint is subjected to axial force, a frictional force is generated at the joint, where the maximum static frictional force is equal to the static friction coefficient multiplied by the axial force. This invention obtains the shear force borne by each beam element and the axial force borne by each ring joint, multiplies the axial force of each beam element by the static frictional force to obtain the frictional force of each beam element, and compares it with the shear force of each beam element.

[0155] Phase 1: If the frictional force of each beam element is not less than its shear force, and the joints do not slip, then input the foundation parameters and the contact area of ​​each beam element into the Phase 1 model for processing, and the equivalent shear stiffness of each beam element can be output; wherein, the Phase 1 model is expressed by the following formula:

[0156]

[0157] In the formula, l b The length of the bolt; l s κ is the annular width of the tunnel segment; s This is the segment ring shear correction factor (the calculation of this value can be found in the literature "A New Method for Calculating the Shear Coefficient of Timoshenko Beam Sections", which will not be detailed here); G s A represents the shear modulus of concrete. s This represents the circumferential cross-sectional area of ​​the tunnel segment.

[0158] Second stage: When the frictional force of each beam element is less than its shear force and the bolt shear stress obtained from the quantification of the shear force of each beam element is not greater than the preset shear stress, the frictional force is insufficient to resist the shear force. The bolts and tenons also begin to function, i.e., the joint slides and the bolts do not yield. The foundation parameters and the contact area of ​​each beam element are input into the second stage model processing to output the equivalent shear stiffness of each beam element. The bolt shear stress is calculated using the following formula:

[0159] τ b =Q / (n b *A b )

[0160] In the formula, τ b For bolt shear stress; n b The number of bolts; A b Let be the cross-sectional area of ​​the bolt.

[0161] The second-stage model is represented by the following formula:

[0162]

[0163] In the formula, n g G represents the number of tenons and countersunk holes in the segment rings. b κ represents the bolt shear modulus. b κ is the bolt shear coefficient; g The shear correction factor for the tenon and mortise joint (the calculation of these two shear correction factors is the same as κ). s A g denoted as , where is the area of ​​the tenon and mortise joint; f is the frictional force.

[0164] Third stage: When the bolt shear stress in each beam element exceeds the preset shear stress, and the bolts begin to yield, the foundation parameters and the contact area of ​​each beam element are input into the third stage model for processing, and the equivalent shear stiffness of each beam element can be output; the third stage model is expressed by the following formula:

[0165]

[0166] In the formula, [τ] is the preset shear stress, which can be set empirically or determined based on historical data. The shear modulus is generally taken as E / 2(1+μ) of the elastic modulus. This is based on the generalized Hooke's law in elasticity theory and the basic assumptions in mechanics of materials, and is applicable to isotropic linear elastic materials. μ is the material's Poisson's ratio. The yield shear stress is generally about 0.577 times the yield tensile stress, which is determined based on the von Mises yield criterion.

[0167] This invention obtains the shear force borne by the beam element and the axial force borne by the ring joint, and quantifies and compares the frictional force and shear force. This allows for a detailed analysis of the working state of the ring joint under different stress conditions, enabling a more accurate assessment of the equivalent shear stiffness of the beam element. Since the mechanical behavior of the ring joint contributes differently to the shear stiffness at different stages, precise differentiation helps improve the accuracy of the calculation results. Furthermore, the scheme not only considers the relationship between frictional force and shear force but also introduces the crucial factor of bolt shear stress, making the calculation of equivalent shear stiffness more consistent with reality and avoiding deviations in the evaluation results due to the neglect of certain factors. Based on the magnitude relationship between frictional force and shear force and the comparison results of bolt shear stress and preset shear stress, different stage models are used for calculation, which can adapt to the different stress stages that the ring joint may experience during the construction of the shield tunnel, thereby improving the accuracy of the equivalent shear stiffness.

[0168] S4. If the longitudinal deformation of each beam element does not meet the preset requirements, the quantification process of the longitudinal deformation of each beam element is repeated until the final longitudinal deformation meets the preset requirements. Based on the single-ring deformation model of the final repeated cycle, the bending mode and shear mode of each beam element are determined to evaluate the safety status of each beam element in the current construction step. Specifically, this invention compares the equivalent bending stiffness and equivalent shear stiffness in the longitudinal deformation at different locations. If both meet the preset requirements (error = |new value - old value| / |old value| ≤ 10), the beam element is considered safe. -4 If the calculation stops, the new value replaces the old value, and the quantization process of the longitudinal deformation of each beam element is repeated until the convergence requirement is met; the quantization process of the longitudinal deformation of the beam element is as follows: Figure 9 As shown.

[0169] In one embodiment, the determination of the bending and shear modes of each beam element based on the single-ring variable model of the final repeated cycle to assess the safety status of each beam element at the current construction step includes:

[0170] The final repeating cycle of the longitudinal deformation of each beam element is taken as the termination cycle, and the bending mode of each beam element is determined based on the joint rotation angle and bolt stress output by the single-ring bending model in the termination cycle.

[0171] Based on the shear force and friction force output by the single-ring shear model in the final round, the shear mode of each beam element is determined by combining the shear stress of each bolt.

[0172] Based on the bending mode and the shear mode, the safety level of each beam element in the current construction step is determined as the output of the safety status assessment result.

[0173] Specifically, this invention uses the final repetition cycle of the longitudinal deformation of each beam element as the termination cycle. The bending mode is determined by the joint rotation angle and bolt stress characteristics, corresponding to the nonlinear change of the equivalent bending stiffness. The division is based on the calculation results from the single-ring bending model. That is, this invention determines the bending mode of each beam element based on the joint rotation angle and bolt stress output by the single-ring bending model in the termination cycle: if the joint rotation angle is 0 (or less than the minimum threshold) and the bolt stress is less than the yield strength, the bending mode of the beam element is mode Ib (joint not open); if the joint rotation angle is greater than 0 and the bolt stress is less than the yield strength, the bending mode of the beam element is mode IIb (partially open); if the joint rotation angle is greater than 0 and the bolt stress is not less than the yield strength, the bending mode of the beam element is mode IIIb (partially open and bolt yielding). In addition, the bending mode of the joint in the shield tunnel can also be directly determined based on the single-ring bending model.

[0174] The shear mode is determined by the sliding state and shear resistance mechanism of the ring joint, corresponding to the nonlinear change of the equivalent shear stiffness. The division is based on the calculation results from the single-ring shear model. That is, this invention determines the shear mode by combining the shear force and friction force output by the single-ring shear model in the final round with the bolt shear stress of each beam element: the first stage corresponds to mode Is (joint not sliding), the second stage corresponds to mode IIs (joint sliding), and the third stage corresponds to mode IIIs (joint sliding and bolt yielding).

[0175] Assign a hazard level to each mode (from low to high, 1-3), namely, safety level 1: Ib, Is (lowest hazard); safety level 2: IIb, IIs (medium hazard); safety level 3: IIIb, IIIs (highest hazard); then calculate the overall safety level according to the principle of the most dangerous and output it as the safety status assessment result: S = max(Sb, Ss), where Sb is the hazard level of the bending mode and Ss is the hazard level of the shear mode.

[0176] This invention comprehensively considers both bending and shear forces, fully covering various mechanical influences that beam elements may experience during construction, making safety assessments more comprehensive and reliable. Based on data from the final repeated cycles, it can dynamically reflect structural changes during construction. Safety levels are determined according to bending and shear patterns, making assessment results more intuitive and easier to understand. Furthermore, it can provide a comprehensive and accurate evaluation of tunnel safety without relying on specifications, considering only the bending and shear nonlinear characteristics of joints, further improving assessment accuracy.

[0177] S5. Update the current construction step to iteratively execute the safety status assessment process of each beam unit in the updated current construction step until all construction steps are completed, so as to generate the safety assessment result of the shield tunnel under construction load.

[0178] Specifically, the construction of a shield tunnel is a dynamic process. This invention updates the current construction step, moves the construction load position (following the advancement of the shield machine), and updates the foundation parameters (considering changes in the strata). Based on the above evaluation process, iteratively executes the safety assessment of all construction steps. That is, for the target ring of each construction step, the process of "multi-ring model solution → single-ring stiffness update → mode determination" is executed until all construction steps (generally 100 steps) are evaluated. The mode changes of all construction steps are accumulated, and the safety level of the target ring changes with the construction step is plotted. The dangerous stage is identified based on the curve, and the safety assessment result of the shield tunnel under construction load is obtained.

[0179] Using a shield tunnel project as a calculation example, the parameters required for the calculation are shown in the table below:

[0180] Table 1 Calculation Parameters

[0181] Parameters Value <![CDATA[Segment ring width l s (m)]]> 2 Segment thickness t (m) 0.6 <![CDATA[Bolt length l b (m)]]> 0.7 <![CDATA[Outer diameter D of the tunnel c (m)]]> 13.8 Bolt diameter d (m) 0.036 <![CDATA[Number of bolts n b > 56 <![CDATA[Elastic modulus E of concrete s (GPa)]]> 34.5 Bolt strength grade 8.8 <![CDATA[Elastic modulus E of the bolt b (GPa)]]> 200 <![CDATA[Yield stress of bolt f yb (MPa)]]> 640

[0182] The cumulative longitudinal deformation diagram and safety zoning diagram obtained using the construction safety assessment method for shield tunnels described in the first aspect are shown below. Figure 10 , Figure 11 As shown.

[0183] This invention addresses the problem that existing technologies fail to consider the stiffness variation characteristics of shield tunnels, making it impossible to accurately solve for the longitudinal mechanical response and thus affecting the accuracy of shield tunnel construction safety assessments. To address this, a construction safety assessment method for shield tunnels is designed. This method provides an accurate data foundation for subsequent analysis by precisely quantifying key parameters, facilitating a more accurate assessment of the tunnel's stress and foundation characteristics during construction and reducing assessment errors caused by inaccurate parameters. The quantified parameters are input into a nonlinear mechanical solution framework composed of a longitudinal multi-ring model and a single-ring variable model to accurately solve for the nonlinear deformation response of the shield tunnel in the longitudinal direction. An iterative processing mechanism ensures that the deformation of the tunnel structure remains within a controllable range, effectively avoiding structural damage and other safety issues caused by excessive deformation, thus improving the safety and reliability of tunnel construction. By updating construction steps to track the stress and deformation of the tunnel structure at different construction stages in real time, the accuracy of shield tunnel construction safety assessments is improved, providing comprehensive and continuous safety assurance for the entire construction process.

[0184] It should be noted that although the steps in the flowchart above are shown sequentially as indicated by the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order requirement for the execution of these steps, and they can be executed in other orders.

[0185] In another embodiment, such as Figure 12 As shown, a second aspect of the present invention provides a construction safety assessment system for shield tunnels, comprising:

[0186] The beam unit discretization module 10 is used to acquire the basic parameters of the shield tunnel in real time during the current construction step, so as to quantify the construction load and foundation coefficient, and discretize the shield tunnel into several beam units.

[0187] The multi-ring scale quantization module 20 is used to input the construction load and the foundation coefficient into the longitudinal multi-ring model constructed based on each beam element for processing, and to obtain the mechanical response data of each beam element by quantization through the transfer matrix method;

[0188] The single-ring scale quantization module 30 is used to input the mechanical response data of each of the above into the single-ring variable model processing and output the longitudinal deformation of each of the beam elements;

[0189] The first state evaluation module 40 is used to repeatedly execute the quantification process of the longitudinal deformation of each beam unit if the longitudinal deformation of each beam unit does not meet the preset requirements, until the final longitudinal deformation meets the preset requirements, and determine the bending mode and shear mode of each beam unit based on the single-ring deformation model of the final repeated rounds, so as to evaluate the safety status of each beam unit in the current construction step.

[0190] The second state assessment module 50 is used to update the current construction step to iteratively perform the assessment process of the safety status of each beam unit in the updated current construction step until all construction steps are completed, so as to generate the safety assessment result of the shield tunnel under construction load.

[0191] It should be noted that each module in the aforementioned construction safety assessment system for shield tunnels can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in a computer device, or stored in the computer device's memory as software, allowing the processor to call and execute the corresponding operations. For specific limitations regarding the construction safety assessment system for shield tunnels, please refer to the limitations of the construction safety assessment method for shield tunnels described above; both have the same function and role, and will not be repeated here.

[0192] A third aspect of the present invention provides an electronic device comprising:

[0193] Processor, memory, and bus;

[0194] The bus is used to connect the processor and the memory;

[0195] The memory is used to store operation instructions;

[0196] The processor is configured to execute operations corresponding to a construction safety assessment method for shield tunnels as shown in the first aspect of the present invention by invoking the operation instructions.

[0197] In one alternative embodiment, an electronic device is provided, such as Figure 13 As shown, Figure 13 The illustrated electronic device 5000 includes a processor 5001 and a memory 5003. The processor 5001 and the memory 5003 are connected, for example, via a bus 5002. Optionally, the electronic device 5000 may also include a transceiver 5004. It should be noted that in practical applications, the transceiver 5004 is not limited to one type, and the structure of this electronic device 5000 does not constitute a limitation on the embodiments of the present invention.

[0198] Processor 5001 may be a CPU, a general-purpose processor, a DSP, an ASIC, an FPGA, or other programmable logic device, transistor logic device, hardware component, or any combination thereof. It may implement or execute the various exemplary logic blocks, modules, and circuits described in connection with this disclosure. Processor 5001 may also be a combination that implements computational functions, such as including one or more microprocessor combinations, a combination of a DSP and a microprocessor, etc.

[0199] Bus 5002 may include a path for transmitting information between the aforementioned components. Bus 5002 may be a PCI bus or an EISA bus, etc. Bus 5002 can be divided into address bus, data bus, control bus, etc. For ease of representation, Figure 13 The bus is represented by a single thick line, but this does not mean that there is only one bus or one type of bus.

[0200] The memory 5003 may be a ROM or other type of static storage device capable of storing static information and instructions, RAM or other type of dynamic storage device capable of storing information and instructions, or it may be an EEPROM, CD-ROM or other optical disc storage, optical disc storage (including compressed optical discs, laser discs, optical discs, digital universal optical discs, Blu-ray discs, etc.), magnetic disk storage media or other magnetic storage devices, or any other medium capable of carrying or storing desired program code in the form of instructions or data structures and accessible by a computer, but is not limited thereto.

[0201] The memory 5003 is used to store application code that executes the present invention, and its execution is controlled by the processor 5001. The processor 5001 is used to execute the application code stored in the memory 5003 to implement the content shown in any of the foregoing method embodiments.

[0202] Among them, electronic devices include, but are not limited to: mobile terminals such as mobile phones, laptops, digital radio receivers, PDAs (personal digital assistants), PADs (tablet computers), PMPs (portable multimedia players), and in-vehicle terminals (such as in-vehicle navigation terminals), as well as fixed terminals such as digital TVs and desktop computers.

[0203] The fourth aspect of the present invention provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the construction safety assessment method for shield tunnels as described in the first aspect of the present invention.

[0204] Another embodiment of the present invention provides a computer-readable storage medium storing a computer program that, when run on a computer, enables the computer to execute the corresponding content in the foregoing method embodiments.

[0205] Furthermore, embodiments of the present invention also provide a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the above-described method.

[0206] In summary, this invention relates to the field of underground engineering technology and discloses a method, system, equipment, and medium for construction safety assessment of shield tunnels. It quantifies the construction load and foundation coefficient in the current construction step and inputs them into a nonlinear mechanical solution framework composed of a longitudinal multi-ring model and a single-ring variable model for processing. This yields the longitudinal deformation of each beam element. If the longitudinal deformation does not meet preset requirements, the quantification process is repeated until the preset requirements are met. The bending and shear modes of each beam element are determined based on the single-ring variable model to assess the safety status of the current construction step. The current construction step is updated, and the assessment process for the safety status of the updated current construction step is iteratively executed until all construction steps are completed, resulting in a safety assessment of the shield tunnel under construction loads. The method accurately solves for the nonlinear deformation response in the longitudinal direction of the shield tunnel and achieves a comprehensive and accurate safety assessment of the shield tunnel.

[0207] The various embodiments in this specification are described in a progressive manner. For directly identical or similar parts of the embodiments, refer to each other. Each embodiment focuses on its differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments. It should be noted that the technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification.

[0208] The above-described embodiments are merely preferred embodiments 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 improvements and substitutions without departing from the principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention. Therefore, the scope of protection of this invention should be determined by the scope of the claims.

Claims

1. A method for construction safety assessment for a shield tunnel, characterized by, The method comprises the following steps: In the current construction step, the basic parameters of the shield tunnel are acquired in real time to quantify the construction load and the foundation coefficient, and the shield tunnel is discretized into a plurality of beam units; The construction load and the foundation coefficient are input into a longitudinal multi-ring model constructed based on each beam unit, and the mechanical response data of each beam unit is quantified by a transfer matrix method, including: establishing the differential equation of each beam unit based on the Timoshenko beam theory and simplifying it into a matrix form to obtain the mechanical model of each beam unit, so as to construct the longitudinal multi-ring model; the longitudinal multi-ring model is subjected to Laplace transformation to obtain an initial parameter solution model, and the coupling stiffness index of each beam unit is quantified to determine the target transfer matrix and the target load influence matrix of each beam unit; the construction load and the foundation coefficient are input into the longitudinal multi-ring model, and the target transfer matrix and the target load influence matrix of each beam unit are combined to transfer from the starting point to the ending point of the shield tunnel to obtain the mechanical response data of each beam unit; Each mechanical response data is input into a single-ring deformation model to output the longitudinal deformation of each beam unit; If the longitudinal deformation of each beam unit does not meet the preset requirement, the quantification process of the longitudinal deformation of each beam unit is repeated until the final longitudinal deformation meets the preset requirement, and the bending mode and the shear mode of each beam unit are determined based on the single-ring deformation model of the final repeated round to evaluate the safety state of each beam unit in the current construction step; The current construction step is updated to iteratively perform the evaluation process of the safety state of each beam unit in the updated current construction step until all construction steps are completed to generate the safety evaluation result of the shield tunnel under the action of the construction load; The single-ring deformation model comprises a single-ring bending model and a single-ring shear model; wherein The input of each mechanical response data into the single-ring deformation model to output the longitudinal deformation of each beam unit comprises: The input of each mechanical response data into the single-ring bending model to output the equivalent bending stiffness and the neutral axis height of each beam unit; The contact area of the inter-ring joint contained in each beam unit is determined based on the neutral axis height, and the input of the foundation parameter into the single-ring shear model to output the equivalent shear stiffness of each beam unit; The equivalent bending stiffness and the equivalent shear stiffness of each beam unit are output as the longitudinal deformation of each beam unit.

2. The construction safety assessment method for a shield tunnel according to claim 1, wherein The construction load comprises a vertical additional bending moment; wherein the vertical additional bending moment is calculated by the following formula: wherein is the vertical additional bending moment; n is the number of jacks; is the number of the first i is the thrust force generated by the first is the number of the first i is the distance of the first 3. The method for construction safety assessment of a shield tunnel according to claim 1, wherein, The quantification of the coupling stiffness index of each beam unit to determine the target transfer matrix and the target load influence matrix of each beam unit comprises: The coupling stiffness index of each beam unit is quantified based on the foundation coefficient; When the coupling stiffness index is less than zero, the foundation parameter, the construction load and the foundation coefficient are input into the target transfer matrix and the target load influence matrix based on the matrix characteristics of the trigonometric function; When the coupling stiffness index is equal to zero, based on the basic parameters, the construction load and the foundation coefficient, and taking a polynomial as a matrix characteristic, the target transfer matrix and the target load influence matrix are constructed; When the coupling stiffness index is greater than zero, based on the basic parameters, the construction load and the foundation coefficient, and taking a hyperbolic function as a matrix characteristic, the target transfer matrix and the target load influence matrix are constructed.

4. The method for construction safety assessment of a shield tunnel according to claim 1, wherein, The single-ring shear model is composed of a first-stage model, a second-stage model and a third-stage model; wherein, The input of the basic parameters into the single-ring shear model for processing outputs the equivalent shear stiffness of each beam element, including: The shear force borne by each beam element and the axial force borne by each ring-to-ring joint are obtained, and the friction force of each beam element is quantified according to the axial force, and compared with each shear force; If each friction force is not less than each shear force, the basic parameters and each contact area are input into the first-stage model for processing, and the equivalent shear stiffness of each beam element is output; If each friction force is less than each shear force and the bolt shear stress obtained based on the quantification of each shear force is not greater than a preset shear stress, the basic parameters and each contact area are input into the second-stage model for processing, and the equivalent shear stiffness of each beam element is output; If each bolt shear stress is greater than the preset shear stress, the basic parameters and each contact area are input into the third-stage model for processing, and the equivalent shear stiffness of each beam element is output.

5. The method for construction safety assessment of a shield tunnel according to claim 4, wherein, The single-ring deformation model based on the final repeated round determines the bending mode and the shear mode of each beam element to evaluate the safety state of each beam element at the current construction step, including: The final repeated round of the longitudinal deformation variable of each beam element is taken as a termination round, and the bending mode of each beam element is determined based on the joint rotation angle and the bolt stress output by the single-ring bending model in the termination round; The shear force and the friction force output by the single-ring shear model in the termination round are combined with each bolt shear stress to determine the shear mode of each beam element; According to each bending mode and each shear mode, the safety level of each beam element at the current construction step is determined as a safety state evaluation result.

6. A construction safety assessment system for a shield tunnel, characterized by, The beam element discretization module is configured to, in a current construction step, acquire the basic parameters of a shield tunnel in real time, quantify the construction load and the foundation coefficient, and discretize the shield tunnel into a plurality of beam elements; ​ The multi-ring scale quantification module is configured to input the construction load and the foundation coefficient into a longitudinal multi-ring model processing based on each beam element, and to obtain mechanical response data of each beam element by a transfer matrix method, including: establishing a differential equation of each beam element based on the Timoshenko beam theory and simplifying the differential equation into a matrix form to obtain a mechanical model of each beam element, so as to construct the longitudinal multi-ring model; performing Laplace transformation on the longitudinal multi-ring model to obtain a primary parameter solution model, and quantifying a coupling stiffness index of each beam element to determine a target transfer matrix and a target load influence matrix of each beam element; inputting the construction load and the foundation coefficient into the longitudinal multi-ring model processing, and combining the target transfer matrix and the target load influence matrix to transfer from a starting point to an ending point of the shield tunnel, so as to obtain the mechanical response data of each beam element; The single-ring scale quantification module is configured to input the mechanical response data into a single-ring deformation model processing, and to output a longitudinal deformation variable of each beam element. The first state evaluation module is configured to repeatedly perform the quantification process of the longitudinal deformation variable of each beam element until the longitudinal deformation variable finally obtained satisfies the preset requirement, and to determine a bending mode and a shear mode of each beam element based on a single-ring deformation model of a final repeated round, so as to evaluate a safety state of each beam element in the current construction step. The second state evaluation module is configured to update the current construction step, to iteratively perform the evaluation process of the safety state of each beam element in the updated current construction step, until all construction steps are completed, so as to generate a safety evaluation result of the shield tunnel under the construction load. The single-ring deformation model includes a single-ring bending model and a single-ring shear model; wherein The inputting of the mechanical response data into the single-ring deformation model processing and the outputting of the longitudinal deformation variable of each beam element include: The inputting of the mechanical response data into the single-ring bending model processing and the outputting of an equivalent bending stiffness and a neutral axis height of each beam element; The determination of a contact area of a ring-to-ring joint of each beam element based on the neutral axis height, so as to input the foundation parameter into the single-ring shear model processing and output an equivalent shear stiffness of each beam element; The outputting of the equivalent bending stiffness and the equivalent shear stiffness of each beam element as the longitudinal deformation variable of each beam element.

7. An electronic device, comprising: A computer readable storage medium includes a stored computer program, wherein a device where the computer readable storage medium is located implements the construction safety evaluation method for a shield tunnel according to any one of claims 1 to 5 when the computer program is executed.

8. A computer-readable storage medium, characterized in that, The computer readable storage medium includes a stored computer program, wherein a device where the computer readable storage medium is located implements the construction safety evaluation method for a shield tunnel according to any one of claims 1 to 5 when the computer program is executed.

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