Method, system and equipment for evaluating safety of tunnel lining

Abstract

The invention relates to the technical field of tunnel safety assessment, and discloses a tunnel lining safety assessment method, system and equipment, and the method comprises the steps: obtaining design parameters of a tunnel structure, and constructing an Euler-Lagrange model according to the design parameters; respectively changing each model parameter in the Euler-Lagrange model, and calculating to obtain a critical value of a circumferential angle of contact loss under different model parameters when the tunnel structure is damaged; constructing a judgment model according to different model parameters and corresponding critical values; the judgment model is used for inputting each model parameter and outputting a tunnel structure safety evaluation result; and the tunnel burial depth, the contact loss position, the longitudinal range of each contact loss and the circumferential angle of each contact loss of the to-be-detected tunnel structure are obtained and input into the judgment model, and a safety evaluation result of the to-be-detected tunnel structure is output. The tunnel operation stage safety evaluation system has the advantage that the effective tunnel operation stage safety evaluation system is provided to monitor the safety state of the tunnel in real time.

Description

Technical Field

[0001] The present invention relates to the technical field of tunnel safety assessment, and in particular to a method, system and equipment for assessing the safety of a tunnel lining. Background Art

[0002] A shield tunnel is a type of tunnel that is constructed using a shield machine. The shield machine is a tunnel construction machine that integrates multiple functions such as excavation, support, soil discharge, and lining. During the construction process, the shield machine advances in the stratum, cutting the soil with the cutter head at its front end, while using the shield shell and segments to support the surrounding rock to prevent the tunnel from collapsing. The excavated soil is transported out of the cave by the excavation machinery, and precast concrete segments are assembled inside the machine to form the permanent lining structure of the tunnel.

[0003] Shield tunnels are widely used in subway construction. The soil around the tunnel serves as both a load on the tunnel structure and an external support condition, together forming a tunnel structure-soil interaction system. During the construction and operation phases, adverse factors such as poor shield machine posture, uneven synchronous grouting, grouting shrinkage, tunnel leakage, and groundwater erosion may all lead to local cavities or gaps on the outside of the tunnel, which are collectively referred to as contact losses.

[0004] During the construction and operation phases of a tunnel, a variety of factors may cause a loss of contact with the soil outside the tunnel, thereby changing the soil's support constraints on the tunnel and the size and distribution of the loads applied by the soil to the tunnel. A large number of engineering practices have shown that changes in the contact conditions between the tunnel and the soil may cause additional deformation and local cracking damage to the tunnel structure. In severe cases, this may lead to local damage to the segments, resulting in large-scale continuous damage to the tunnel.

[0005] In order to ensure the safe operation of the tunnel, long-term safety monitoring must be carried out to understand the stress and internal environmental conditions of the tunnel structure in harsh environments, so as to timely understand the location and degree of damage to the tunnel structure, and then evaluate the structural safety status and internal environment and take effective measures.

[0006] Existing monitoring of tunnel safety often uses ellipticity, tunnel vibration signals, multi-source information, etc. to monitor and warn of the safety of operating tunnels. However, changes in ellipticity cannot detect damage to joints; noise factors have a large impact when acquiring tunnel vibration signals, making it difficult to obtain accurate conclusions; multi-source information includes factors such as structure, stress, and environment, and the amount of data required for processing is large, which places high demands on algorithms and is difficult to promote... At present, there is no effective tunnel operation stage safety assessment system to monitor the safety status of tunnels in real time.

[0007] Therefore, it is urgent to develop a tunnel lining safety assessment method to solve the above problems. Summary of the invention

[0008] In order to solve the above technical problems, the present invention provides a method, system and equipment for evaluating the safety of tunnel lining, and provides an effective safety evaluation system for the tunnel operation stage to monitor the safety status of the tunnel in real time.

[0009] In a first aspect, the present invention provides a method for evaluating the safety of a tunnel lining, comprising the following steps: S1. Obtain design parameters of the tunnel structure and construct an Euler-Lagrangian model according to the design parameters; S2. respectively changing the model parameters in the Euler-Lagrangian model, and calculating the critical value of the circumferential angle of the contact loss when the tunnel structure is damaged under different model parameters; the model parameters include tunnel burial depth, contact loss position, and longitudinal range of the contact loss; S3. Constructing a judgment model according to different model parameters and corresponding critical values ​​of circumferential angles; the judgment model is used to input various model parameters and output safety assessment results of the tunnel structure; S4. Obtain the tunnel burial depth, contact loss position, longitudinal range of each contact loss and circumferential angle of each contact loss of the tunnel structure to be tested, input them into the judgment model, and output the safety assessment result of the tunnel structure to be tested.

[0010] Furthermore, the soil in the Euler-Lagrangian model is set as an Euler material, the Euler material flows within a preset Euler boundary, and the Mohr-Coulomb model is used to simulate the flow of the soil; The tunnel structure in the Euler-Lagrangian model is modeled using Lagrangian grids. The tunnel structure includes several rings, each of which is composed of several segments. The elastic model is used to simulate the stress conditions of each segment.

[0011] Furthermore, the junctions between the two ends of the tunnel structure and the soil are set as zero displacement boundary conditions, and the boundary of the soil is set as zero displacement boundary conditions.

[0012] Furthermore, adjacent segments are connected by a plurality of connectors, adjacent rings are connected by a plurality of connectors, and adjacent rings are connected by a staggered assembly method; Each connector is constructed by setting up the Eulerian boundary surfaces.

[0013] Furthermore, the judgment model is as follows: different levels are established according to different model parameter ranges and critical values ​​of the contact loss circumferential angle.

[0014] Furthermore, different levels are established according to different model parameter ranges and critical values ​​of the contact loss circumferential angle, including: S31, preset the tunnel burial depth and the contact loss position; set a first preset number of rings and a second preset number of rings, the second preset number of rings being greater than or equal to the first preset number of rings; S32, setting the longitudinal range of the contact loss to a first preset number of rings; S33, gradually increasing the circumferential angle of contact loss from zero, calculating the circumferential angle of contact loss when the tunnel structure is damaged, and obtaining a critical value of the circumferential angle; recording the tunnel burial depth, contact loss position, longitudinal range of contact loss and critical value of the circumferential angle at this time as a level; S34, calculating in real time the bending moment values ​​at each inter-ring joint and intra-ring joint covered by the contact loss in the Euler-Lagrange model, and determining whether there is a situation where the bending moment value is greater than its corresponding bearing capacity limit, if so, proceeding to S35; otherwise, accumulating the longitudinal range of the contact loss by a second preset number of rings, and proceeding to S33; S35, changing the tunnel burial depth and the contact loss position, and repeatedly entering S32 until the traversal of the tunnel burial depth and the contact loss position is completed.

[0015] Furthermore, the judgment model is input for calculation and the safety assessment result of the tunnel structure to be tested is output, including: judging the level corresponding to the tunnel burial depth, the position of the contact loss and the longitudinal range of the contact loss, and then judging whether the circumferential angle of each contact loss of the tunnel structure to be tested is greater than or equal to the critical value of the circumferential angle of the corresponding level; if it is greater than or equal to the critical value of the circumferential angle of the corresponding level, it is judged that several sections of the ring at the contact loss are in an unsafe state; otherwise, it is judged that several sections of the ring at the contact loss are in a safe state.

[0016] In a second aspect, the present invention provides a tunnel lining safety assessment system, comprising the following modules: Simulation module: obtain the design parameters of the tunnel structure, and construct the Euler-Lagrangian model according to the design parameters; change the various model parameters in the Euler-Lagrangian model respectively, and calculate the critical value of the circumferential angle of the contact loss when the tunnel structure is damaged under different model parameters; the model parameters include the tunnel burial depth, contact loss location, and longitudinal range of the contact loss; Model building module; connected with the simulation module, used to build a judgment model according to different model parameters and the corresponding critical values ​​of the circumferential angle; the judgment model is used to input various model parameters and output the safety assessment results of the tunnel structure; Evaluation module: connected to the model building module, used to obtain the tunnel burial depth, contact loss position, longitudinal range of each contact loss and circumferential angle of each contact loss of the tunnel structure to be tested, and input them into the judgment model to output the safety evaluation result of the tunnel structure to be tested.

[0017] In a third aspect, the present invention provides an electronic device, comprising: a processor and a memory; the processor is used to execute the steps of the method of the first aspect by calling a program or instruction stored in the memory.

[0018] The embodiments of the present invention have the following technical effects: The present application constructs an Euler-Lagrangian model to obtain relevant parameters generated by contact loss around the tunnel structure, namely, tunnel burial depth, contact loss location, and longitudinal range of contact loss; wherein each parameter is directly related to the safety of the tunnel structure, and a relationship is established between each parameter and the safety of the tunnel structure, and a judgment model is obtained according to the classification of each parameter, and then the safety of the track structure to be tested is judged according to the level corresponding to the parameter of the track structure to be tested, which greatly reduces the complexity of data processing, improves data processing efficiency and accuracy, and ensures the accuracy of the judgment result; The present application provides an effective tunnel operation phase safety assessment system to monitor the safety status of the tunnel in real time. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 is a flow chart of a method for evaluating the safety of a tunnel lining provided by an embodiment of the present invention; Figure 2 is a schematic diagram of the structure of the Euler-Lagrangian model provided by an embodiment of the present invention; Figure 3 is a schematic cross-sectional view of a tunnel structure provided by an embodiment of the present invention; Figure 4 is a schematic diagram of the location of contact loss provided by an embodiment of the present invention; Figure 5 is a schematic diagram of damage caused by contact loss provided by an embodiment of the present invention; Figure 6 It is a schematic diagram of various levels provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0022] Example 1 Firstly, it should be noted that in the present application, the longitudinal direction refers to the extension direction of the pipeline, and the circumferential direction refers to the direction perpendicular to the extension direction of the pipeline.

[0023] Figure 1 1 is a flow chart of a method for evaluating the safety of a tunnel lining provided by an embodiment of the present invention. Figure 1 , specifically including: S1. Obtain the design parameters of the tunnel structure and construct an Euler-Lagrangian model based on the design parameters.

[0024] The design parameters of the tunnel structure include tunnel length, diameter, etc. The data required in the model construction process can be obtained by yourself.

[0025] Based on the Euler-Lagrangian coupling method, a numerical model is constructed, which has good applicability in solving large deformation geotechnical engineering problems. The specific settings of each part are shown below: (1) Soil like Figure 2 As shown in the figure, the yellow part is the soil structure. The physical properties and engineering characteristics of the soil are simulated by constructing the soil structure. The soil is modeled using Euler materials. By setting the Euler boundary in the model, the soil within the predetermined Euler boundary can flow through the boundary and disappear, while the soil outside the boundary is not affected. Gaps are created on the top surface of the soil and in the tunnel to accommodate soil with a certain displacement. The Mohr-Coulomb model is used to simulate the flow behavior of the soil, and the parameter configuration of the soil is shown in Table 1. The boundary of the soil is set to a zero displacement boundary condition. Specifically, zero velocity boundary conditions are applied to the four vertical surfaces (parallel to the direction of gravity) and the bottom of the soil structure, so that the velocity of the soil in the vertical direction of these surfaces is zero.

[0026] Table 1 Parameter configuration of soil and segments

[0027] (2) Tunnel structure Figure 2 The cylindrical structure in the figure is the constructed tunnel structure. The tunnel structure is modeled using Lagrangian grids. The tunnel structure includes several rings, each of which is composed of several segments. The elastic model is used to simulate the stress conditions of each segment.

[0028] For example, according to the geometric dimensions of the shield tunnel commonly used in a certain city, each section (W) is surrounded by 6 segments, including 1 key segment with a central angle of 22.5° and 5 standard segments with a central angle of 67.5°. The outer diameter (D) of the tunnel structure is 6.2 meters. The length (W) of each ring is 1.2 meters and the thickness of the segment is 0.35 meters. It should be noted that the key segment is always located in the upper half of the tunnel structure. The elastic model is used to reflect the behavior of the segment and simulate the stress condition of the segment. The parameters of the segment are shown in Table 1. The two ends of the tunnel structure and the junction of the soil are set to zero displacement boundary conditions so that the velocity in the vertical direction of the contact is zero. The interaction between the soil and the tunnel structure is implemented using the "general contact" algorithm based on the penalty contact method. The friction coefficient between the soil and the segments is 0.4, and the lateral earth pressure coefficient K0 is set to 0.5. Based on the kinetic energy, a time step of 2 seconds is used to allow the entire system to reach a steady state.

[0029] (3) Seams The joint is an important structure that connects the various parts of the entire tunnel structure. The interaction between adjacent segments can be reflected by the set connectors.

[0030] In the above-constructed model, two adjacent segments of the same ring can be connected by two connectors, which is defined as annular joints; adjacent rings are connected by staggered assembly method, assuming that OA is the position line, see Figure 3 , then the OA lines of adjacent rings are not parallel. Two adjacent rings are connected by 16 connectors, which are defined as longitudinal seams. The connectors can be bolts, which are evenly distributed in the seams to meet actual needs, and this application does not make specific restrictions.

[0031] In the model, the seams, ie the individual connectors, are realized by setting the Euler boundary surfaces.

[0032] (4) Contact loss In the present application, the soil within the contact loss range is set to disappear, so that contact loss occurs between the tunnel and the soil.

[0033] S2. respectively changing the model parameters in the Euler-Lagrangian model, and calculating the critical value of the circumferential angle of the contact loss when the tunnel structure is damaged under different model parameters; the model parameters include tunnel burial depth, contact loss position, and longitudinal range of the contact loss; First, after the joint is formed between the tunnel and the surrounding soil, a small amount of soil collapse will occur at the edge of the contact loss. Therefore, during the calculation process, the range of the actual contact loss is slightly larger than the predetermined range.

[0034] (1) Contact loss location For example, tunnel loss locations are often divided into three parts, see Figure 4 , which are the tunnel bottom, tunnel top and tunnel waist respectively. If the tunnel loss settings are the same and only differ in position, the tunnel loss of each part will have different damage effects on the tunnel structure.

[0035] In this application, the relevant parameters related to contact loss can be obtained and calculated through radar and other equipment, which are all existing technologies and will not be explained in detail in this application.

[0036] (2) Tunnel depth When the contact loss is located below the tunnel floor, the deformation development pattern of tunnels with different tunnel depths is the same, but as the contact loss develops, the deformation of the tunnel with a larger coverage depth is more severe.

[0037] Exemplarily, the tunnel depth ranges from 0 to 20 meters. In numerical simulations, the tunnel depth is often set to a multiple of the tunnel diameter.

[0038] After simulation, the tunnel burial depth of the first group of tunnel structures is set to 2D, and the tunnel burial depth of the second group of tunnel structures is set to 4D. Here, the outer diameter D of the tunnel structure is used as the unit. The soil pressure acting on the first group is smaller than that on the second group, which makes the uneven load acting on the tunnel structure due to contact loss larger. With the further development of contact loss, the deformation of the tunnel structure of the second group is more obvious.

[0039] It should be noted that the tunnel burial depth in the present application refers to the distance from the top of the tunnel structure to the ground, and this data can be directly obtained based on the tunnel design drawings, etc.

[0040] (3) Longitudinal range of contact loss The longitudinal range of the contact loss is the total length of the contact loss along the tunnel direction, which can be collected and calculated based on the aforementioned radar and other equipment.

[0041] First, the relevant influence of contact loss on the deformation of tunnel structure is explained: In a specific embodiment, the outer diameter of the tunnel is D, and it is assumed that the cover depth of the tunnel is 2D, and the contact loss occurs at the bottom of the tunnel; the longitudinal dimension of the contact loss is 3 meters, that is, the length of the contact loss along the tunnel direction is the total length of the two semi-rings.

[0042] Based on the contact pressure generated by the soil on the tunnel structure, the actual contact loss range between the tunnel structure and the surrounding soil is determined. As shown in Table 2, for each level of contact loss, the range of the tunnel structure corresponding to the contact loss is determined, which is represented by the degree of the circumferential angle corresponding to the tunnel structure.

[0043]

[0044] A total of four rings, rings 1 to 4, are set, and the contact loss covers the bottom of rings 1 to 3. After calculation, the changes in the horizontal and vertical diameters of the rings relative to their initial states are compared before and after the formation of each level of contact loss. As the contact loss develops, the vertical diameter of the rings within the contact loss range (i.e., rings 1 to 3) increases, and the horizontal diameter decreases. Before the contact loss forms, the earth pressure acting on each ring is similar to an annular force, which limits the deformation of rings 1 to 3. After the contact loss forms under the tunnel, the annular effect of the earth pressure disappears and the rings deform. Due to the action of the earth pressure, the rings are squeezed due to the contact loss.

[0045] For the 4th ring outside the contact loss range, when the annular angle corresponding to the contact loss is less than 30°, its diameter change increases; and when the annular angle corresponding to the contact loss exceeds 30°, its diameter change decreases. However, the change in the diameter of the 4th ring is limited, which indicates that the contact loss has a significant impact on the rings within its range.

[0046] Illustrate the effect of contact loss on a joint: As the contact loss develops, each joint gradually fails. First of all, it should be noted that the longitudinal joint is mainly shear failure, while the circumferential joint mainly includes shear failure and bending failure. Shear failure and bending failure are two basic failure modes in structural mechanics.

[0047] Based on the above parameter settings, further experiments are conducted. Figure 5 , when the contact loss develops to the third level, the three longitudinal joints between the second and fourth rings first fail in shear. As the contact loss develops, the third ring deforms in the direction of the contact loss; but the contact loss has limited effect on the fourth ring; therefore, the misalignment between the third and fourth rings increases, especially at the bottom plate position of the ring, and the longitudinal joints between the third and fourth rings should fail first.

[0048] When the contact loss developed to the fourth level, all 19 failed longitudinal joints showed shear failure, of which 9 longitudinal joints were located between the third and fourth rings. Since the rings were assembled in a staggered manner, there was no difference in the deformation of adjacent rings, and the misalignment between the rings also led to the failure of the annular joints. The eight annular joints of the first to third rings suffered bending failure due to excessive deformation of the rings.

[0049] In addition, shear failure occurred in three circumferential joints at the bottom plate position of rings 1 to 3. The rings are assembled by staggered connection, so the joints at the bottom plate position are also misaligned. At this time, almost half of the longitudinal joints between the 3rd and 4th rings failed, and the connection between the two rings was weakened. The effect of contact loss on the 4th ring is transmitted by the longitudinal joints between the 3rd and 4th rings, and after the connection is weakened, the effect of contact loss on the 4th ring almost disappears, further indicating that contact loss only has a significant effect on the rings within its range.

[0050] When the contact loss range continued to increase to the fifth level, the four annular joints of the 1st to 3rd rings that experienced bending failure in the previous level also experienced shear failure, and one annular joint in the 3rd ring suffered both bending and shear failure.

[0051] In summary, when the contact loss develops within a certain range, the safety of the tunnel structure will be significantly affected within this range.

[0052] The following is an analysis of the parameters related to contact loss to obtain the correlation between safety and various parameters: Based on the settings of the above parameters, structures, etc., expressed in units of the longitudinal length of a single-segment ring, when the contact loss is located below the tunnel floor and the longitudinal range of the contact loss is 2.5 ring lengths, the critical value of its annular angle is 30°, that is, the degree value of the central angle of the covered tunnel structure. When it is greater than this degree, the tunnel structure is severely deformed and the tunnel is in an unsafe state. Similarly, under the condition of 2D tunnel burial depth, when the contact loss is located outside the tunnel waist and the longitudinal range of the contact loss is 2.5 rings, the critical value of its annular angle is also 30°; when the contact loss is located at the top of the tunnel and the longitudinal range of the contact loss is 2.5 rings, the critical value of its annular angle is 35°. When the tunnel burial depth is 4D, if the contact loss is located below the tunnel floor and the longitudinal range of the contact loss is 2.5 rings, the critical value of its annular angle is 15°. Therefore, by changing the tunnel burial depth and the position of the contact loss, the critical value of the annular angle corresponding to each contact loss in a safe state can be uniquely obtained.

[0053] By further changing the tunnel burial depth, contact loss position and longitudinal range of contact loss, it can be obtained that the maximum value of the circumferential angle corresponding to the contact loss will not exceed 90°, because in actual engineering, it is almost impossible to form a contact loss with an circumferential angle of 90°, and when the circumferential angle of the contact loss is close to 90°, the soil around the contact loss will collapse, thus affecting the calculation results.

[0054] Figure 6The circumferential angles of contact loss under different conditions are listed; it should be noted that when the longitudinal range of the contact loss is 0.5 ring length, the critical value of the circumferential angle of contact loss does not exist, that is, during the development of contact loss, the tunnel structure will not fail.

[0055] When contact loss is formed at different positions outside the tunnel and the longitudinal range of contact loss is the same, the critical value of the circumferential angle of contact loss is different. As the longitudinal range of contact loss increases from 1.5 rings to 3.5 rings, when the contact loss is located below the tunnel floor, the critical value of its circumferential angle decreases from 60° to 25°; when the contact loss is located outside the tunnel waist, the critical value of its circumferential angle decreases from 45° to 30°; when the contact loss is located at the top of the tunnel, the critical value of its circumferential angle also decreases from 45° to 30°. When the tunnel depth is 4D and the contact loss is located below the tunnel floor, as the longitudinal range of contact loss increases from 1.5 rings to 2.5 rings, the critical value of its circumferential angle decreases from 22.5° to 15°. When the longitudinal range of tunnel contact loss increases to a certain value, the critical value of the circumferential angle of contact loss decreases to the minimum value and no longer decreases further.

[0056] When the tunnel depth is 4D, the critical size of the contact loss changes with the longitudinal range of the contact loss in the same way as when the tunnel depth is 2D. However, when the tunnel depth is 4D, the critical value of the circumferential angle of the contact loss is smaller than when the tunnel depth is 2D. Under the condition of 4D tunnel depth, when the critical value of the circumferential angle of the contact loss reaches the minimum value, the corresponding longitudinal range of the contact loss is 2.5 rings, which is also smaller than the case of 2D tunnel depth and the longitudinal range of the contact loss is 3.5 rings.

[0057] As the longitudinal range of contact loss increases, the critical value of its circumferential angle will decrease. However, the critical value of the circumferential angle will not decrease infinitely as the longitudinal range of contact loss increases. When the longitudinal range of contact loss reaches a certain level, its critical value will no longer change. As the longitudinal range of contact loss expands, the critical value of the circumferential angle remains at 30°. That is, when the circumferential angle of contact loss is less than 30°, the longitudinal range of contact loss will not affect the safety of the tunnel structure.

[0058] In summary, once the contact loss reaches the critical value of the circumferential angle, the deformation of the tunnel will cause the joints to begin to fail, thus affecting the safety of the entire tunnel structure; and if the circumferential angle of the contact loss is less than the critical value, it indicates that the tunnel structure is temporarily safe. Therefore, by constructing the relationship between the critical value of the circumferential angle, the tunnel depth, the contact loss position, the longitudinal range of the contact loss and the tunnel safety, by obtaining various parameters, we can directly draw a conclusion on whether the tunnel is safe.

[0059] S3. Construct a judgment model according to different model parameters and corresponding critical values ​​of circumferential angles; the judgment model is used to input various model parameters and output safety assessment results of the tunnel structure.

[0060] The judgment model is as follows: different levels are established according to different model parameter ranges and critical values ​​of the contact loss circumferential angle.

[0061] Specifically, the process of establishing the hierarchy is as follows: S31, preset tunnel burial depth and contact loss position; set a first preset number of rings and a second preset number of rings, the second preset number of rings being greater than or equal to the first preset number of rings.

[0062] S32, setting the longitudinal range of the contact loss to a first preset number of rings.

[0063] For example, in the simulation of the present application, see Figure 6 , only half of the contact loss is considered, so the first preset number of rings is set to 0.5 rings. The first preset number of rings can be set according to actual conditions and can be regarded as the minimum unit of the longitudinal range of the contact loss.

[0064] S33, gradually increasing the circumferential angle of contact loss from zero, calculating the circumferential angle of contact loss when the tunnel structure is damaged, and obtaining a critical value of the circumferential angle; recording the tunnel burial depth, contact loss position, longitudinal range of contact loss and critical value of the circumferential angle at this time as a level; S34. Calculate in real time the bending moment values ​​at each inter-ring joint and intra-ring joint covered by the contact loss in the Euler-Lagrange model, and determine whether there is a situation where the bending moment value is greater than its corresponding bearing capacity limit. If so, enter S35; otherwise, add the second preset number of rings to the longitudinal range of the contact loss and enter S33.

[0065] The second preset number of rings is set to 1 ring to ensure that each ring is traversed without omission, and it should be noted that during the development of contact loss, the tunnel structure does not fail.

[0066] The inter-ring joint is the part where the segments on the ring are close to each other, and the inter-ring joint is the part where the rings are close to each other. When the real-time bending moment value at each inter-ring joint and the inner ring joint is greater than its corresponding bearing capacity limit, it means that the connection is damaged and the tunnel is in an unsafe state; otherwise, it means that the tunnel is still in a safe state.

[0067] Specifically, the bearing capacity limit of the inner ring joint is calculated by the following method: The axial force and bending moment values ​​at each inner joint of the ring covered by contact loss in the Euler-Lagrange model are obtained respectively. The bending moment when the inner side of the inner joint is subjected to tension and the outer side is subjected to pressure is a positive bending moment value, and the bending moment when the outer side is subjected to pressure and the inner side is subjected to tension is a negative bending moment value. It can be simply judged according to the connection conditions of the inner and outer sides. For example, if the inner side is separated, it means that the inner side is subjected to tension, which is a positive bending moment; if the outer side is separated, it means that the outer side is subjected to tension, which is a negative bending moment.

[0068] In one embodiment, at a certain inner ring joint, when shear failure or bending failure begins to occur, the positive moment ultimate bearing capacity is fitted in the form of a polynomial about the axial force of the inner ring joint to simplify the curve expression. The relationship between the positive moment ultimate bearing capacity and the axial force of the inner ring joint is obtained by fitting: , Where F is the axial force.

[0069] In one embodiment, at a certain inter-ring joint, when shear failure or bending failure begins to occur, the negative moment ultimate bearing capacity is fitted in the form of a polynomial about the axial force of the inner-ring joint to simplify the curve expression. The relationship between the negative moment ultimate bearing capacity and the axial force of the inner-ring joint is obtained by fitting: , In fact, there is a concave and convex structure in the inter-ring joint. The stress of the inter-ring joint will cause the inter-ring joint to be misaligned. When the inside of the pipe segment where the concave tenon is located is sheared by the convex tenon, the bearing capacity is low. It is taken as the bearing capacity limit M3 and can be calculated by the following formula: .

[0070] In summary, the present application establishes a relationship between the bearing capacity limit and the axial force. Therefore, the bearing capacity limit can be determined by the real-time axial force at each inter-ring joint and intra-ring joint, thereby obtaining the size relationship between the real-time bending moment value and its corresponding bearing capacity limit.

[0071] S35, changing the tunnel burial depth and the contact loss position, and repeatedly entering S32 until the traversal of the tunnel burial depth and the contact loss position is completed.

[0072] For the longitudinal range of tunnel burial depth and contact loss, the setting of each level value can be set according to local standards, experience and different working conditions, and this application does not limit it.

[0073] See also Figure 6The levels are divided into one level, when the tunnel depth is less than or equal to 2D, the contact loss position is located at the waist, the longitudinal range of the contact loss is greater than 1.5 and less than 2.5 rings, and the circumferential angle is greater than or equal to 30°, it is a level, and the corresponding tunnel structure is in an unsafe state; for example, when the tunnel depth is greater than 2D and less than or equal to 4D, the contact loss position is located at the bottom, the longitudinal range of the contact loss is greater than 3.5 rings and less than or equal to 4.5 rings, and the circumferential angle is greater than or equal to 22.5°, it is a level, and the corresponding tunnel structure is in an unsafe state. The same is true for other levels, which are not explained here one by one. By setting different levels for comparison, the amount of calculation is greatly reduced, and the accuracy of the evaluation results is guaranteed, making it easier to conduct real-time safety evaluation of tunnel structures.

[0074] S4. Obtain the tunnel burial depth, contact loss position, longitudinal range of each contact loss and circumferential angle of each contact loss of the tunnel structure to be tested, input them into the judgment model for calculation, and output the safety assessment result of the tunnel structure to be tested.

[0075] Specifically, the level corresponding to the tunnel burial depth, the location of the contact loss, and the longitudinal range of the contact loss is determined, and then the circumferential angle of each contact loss of the tunnel structure to be tested is determined to be greater than or equal to the critical value of the circumferential angle of the corresponding level; if it is greater than or equal to the critical value of the circumferential angle of the corresponding level, then several sections of the ring at the contact loss are determined to be in an unsafe state; otherwise, several sections of the ring at the contact loss are determined to be in a safe state. Exemplarily, the tunnel burial depth is 2D, the contact loss position is at the top, and the longitudinal range of the contact loss is 2. At this time, if the circumferential angle is 45°, it is greater than the critical value of the circumferential angle, and the tunnel structure at this location is in an unsafe state, and structural cracks may have occurred, and maintenance is required; if the circumferential angle is 20°, then the tunnel structure at this location is considered to be in a safe state.

[0076] Based on the above technical solution, the present application provides an effective tunnel operation phase safety assessment system to monitor the safety status of the tunnel in real time.

[0077] Example 2 Based on the content of Example 1, the present application provides a tunnel lining safety assessment system, including: Simulation module: obtain the design parameters of the tunnel structure, and construct the Euler-Lagrangian model according to the design parameters; change the various model parameters in the Euler-Lagrangian model respectively, and calculate the critical value of the circumferential angle of the contact loss when the tunnel structure is damaged under different model parameters; the model parameters include the tunnel burial depth, contact loss location, and longitudinal range of the contact loss; Model building module; connected with the simulation module, used to build a judgment model according to different model parameters and the corresponding critical values ​​of the circumferential angle; the judgment model is used to input various model parameters and output the safety assessment results of the tunnel structure; Evaluation module: connected to the model building module, used to obtain the tunnel burial depth, contact loss position, longitudinal range of each contact loss and circumferential angle of each contact loss of the tunnel structure to be tested, and input them into the judgment model to output the safety evaluation result of the tunnel structure to be tested.

[0078] For other details, see Example 1, which will not be described in detail here.

[0079] Example 3 The present application provides an electronic device, which includes: a processor and a memory; the processor is used to execute the steps of the method in Example 1 by calling a program or instruction stored in the memory.

[0080] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the technical solutions of the embodiments of the present invention.

Claims

1. A method for evaluating the safety of a tunnel lining, characterized in that: The steps include: S1. Obtain design parameters of the tunnel structure, and construct an Euler-Lagrangian model according to the design parameters; S2. respectively changing the model parameters in the Euler-Lagrangian model, and calculating the critical value of the circumferential angle of the contact loss when the tunnel structure is damaged under different model parameters; the model parameters include the tunnel burial depth, the contact loss position, and the longitudinal range of the contact loss; S3. Constructing a judgment model according to different model parameters and corresponding critical values ​​of circumferential angles; the judgment model is used to input various model parameters and output a safety assessment result of the tunnel structure; S4. Obtain the tunnel burial depth, contact loss position, longitudinal range of each contact loss and circumferential angle of each contact loss of the tunnel structure to be tested, input them into the judgment model, and output the safety assessment result of the tunnel structure to be tested.

2. A method for evaluating the safety of a tunnel lining according to claim 1, characterized in that: The soil in the Euler-Lagrangian model is set as an Euler material, the Euler material flows within a preset Euler boundary, and the flow of the soil is simulated using the Mohr-Coulomb model; The tunnel structure in the Euler-Lagrangian model is modeled using Lagrangian grids. The tunnel structure includes a plurality of rings, each of which is composed of a plurality of segments. The elastic model is used to simulate the stress conditions of each segment.

3. A method for evaluating the safety of a tunnel lining according to claim 2, characterized in that: The junctions between the two ends of the tunnel structure and the soil are set as zero displacement boundary conditions, and the boundary of the soil is set as zero displacement boundary conditions.

4. A method for evaluating the safety of a tunnel lining according to claim 2, characterized in that: Adjacent segments are connected by several connectors, adjacent rings are connected by several connectors, and adjacent rings are connected by staggered assembly method; Each connector is constructed by setting up the Eulerian boundary surfaces.

5. A method for evaluating the safety of a tunnel lining according to claim 1, characterized in that: The judgment model is as follows: different levels are established according to different model parameter ranges and critical values ​​of the contact loss circumferential angle.

6. A method for evaluating the safety of a tunnel lining according to claim 5, characterized in that: Different levels are established according to different model parameter ranges and critical values ​​of contact loss circumferential angles, including: S31, preset the tunnel burial depth and the contact loss position; set a first preset number of rings and a second preset number of rings, the second preset number of rings being greater than or equal to the first preset number of rings; S32, setting the longitudinal range of the contact loss to a first preset number of rings; S33, gradually increasing the circumferential angle of contact loss from zero, calculating the circumferential angle of contact loss when the tunnel structure is damaged, and obtaining a critical value of the circumferential angle; recording the tunnel burial depth, contact loss position, longitudinal range of contact loss and critical value of the circumferential angle at this time as a level; S34, calculating in real time the bending moment values ​​at each inter-ring joint and intra-ring joint covered by the contact loss in the Euler-Lagrange model, and determining whether there is a situation where the bending moment value is greater than its corresponding bearing capacity limit, if so, proceeding to S35; otherwise, accumulating the longitudinal range of the contact loss by a second preset number of rings, and proceeding to S33; S35, changing the tunnel burial depth and the contact loss position, and repeatedly entering S32 until the traversal of the tunnel burial depth and the contact loss position is completed.

7. A method for evaluating the safety of a tunnel lining according to claim 6, characterized in that: In the input judgment model, the safety assessment result of the tunnel structure to be tested is output, including: judging the level corresponding to the tunnel burial depth, the position of the contact loss and the longitudinal range of the contact loss, and then judging whether the circumferential angle of each contact loss of the tunnel structure to be tested is greater than or equal to the critical value of the circumferential angle of the corresponding level; if it is greater than or equal to the critical value of the circumferential angle of the corresponding level, it is judged that several sections of the ring at the contact loss are in an unsafe state; otherwise, it is judged that several sections of the ring at the contact loss are in a safe state.

8. A tunnel lining safety assessment system, used to implement the steps of a tunnel lining safety assessment method according to any one of claims 1 to 7, characterized in that: Includes the following modules: Simulation module: obtaining the design parameters of the tunnel structure, and constructing the Euler-Lagrangian model according to the design parameters; respectively changing the various model parameters in the Euler-Lagrangian model, and calculating the critical value of the circumferential angle of the contact loss when the tunnel structure is damaged under different model parameters; the model parameters include the tunnel burial depth, the contact loss position, and the longitudinal range of the contact loss; A model building module; connected to the simulation module, used to build a judgment model according to different model parameters and corresponding critical values ​​of the circumferential angle; the judgment model is used to input various model parameters and output the safety assessment result of the tunnel structure; Evaluation module: connected to the model building module, used to obtain the tunnel burial depth, contact loss position, longitudinal range of each contact loss and circumferential angle of each contact loss of the tunnel structure to be tested, and input them into the judgment model to output the safety evaluation result of the tunnel structure to be tested.

9. An electronic device, characterized in that: The electronic device comprises: Processor and memory; The processor is configured to execute the steps of the method according to any one of claims 1 to 7 by calling the program or instruction stored in the memory.

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