A method, system and device for evaluating the safety of tunnel lining

Abstract

The present invention relates to the technical field of tunnel safety assessment, and discloses an assessment method, system and device for the safety of tunnel linings, including: obtaining the design parameters of the 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 the critical value of the circumferential angle of contact loss when the tunnel structure is damaged under different model parameters; constructing a judgment model according to different model parameters and the corresponding critical values; the judgment model is used to input each model parameter and output the safety assessment result of the tunnel structure; obtaining 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 measured, and inputting them into the judgment model to output the safety assessment result of the tunnel structure to be measured. The advantage of this application is to provide an effective tunnel operation stage safety assessment system 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] To solve the above technical problems, the present invention provides a method, a system and a device for evaluating the safety of a tunnel lining, and provides an effective safety evaluation system during the tunnel operation stage to monitor the safety state 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:

[0010] S1. Obtain the design parameters of the tunnel structure, and construct an Euler-Lagrange model according to the design parameters;

[0011] S2. Change each model parameter in the Euler-Lagrange 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, the contact loss position, and the longitudinal range of the contact loss;

[0012] S3. Construct a judgment model according to different model parameters and the corresponding critical values of the circumferential angle; the judgment model is used to input each model parameter and output the safety evaluation result of the tunnel structure;

[0013] S4. Obtain 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 tunnel structure to be measured, and input them into the judgment model to output the safety evaluation result of the tunnel structure to be measured.

[0014] Further, the soil in the Euler-Lagrange model is set as an Euler material, and the Euler material flows within a preset Euler boundary, and the Mohr-Coulomb model is used to simulate the flow of the soil;

[0015] The tunnel structure in the Euler-Lagrange model is modeled using Lagrangian grids. The tunnel structure includes several segments of rings, and each segment of ring is composed of several segments of lining segments. The elastic model is used to simulate the stress conditions of each segment of lining segment.

[0016] Further, the connections between the two ends of the tunnel structure and the soil are set as zero-displacement boundary conditions, and the boundaries of the soil are set as zero-displacement boundary conditions.

[0017] Further, several connecting members are used to connect adjacent segments of lining segments, and several connecting members are used to connect adjacent rings. The adjacent rings are connected by the staggered joint assembly method;

[0018] Each connecting member is constructed by setting the Euler boundary surface.

[0019] Further, the judgment model is: different levels are established according to different model parameter ranges and the critical values of the circumferential angle of the contact loss.

[0020] Further, different levels are established according to different ranges of model parameters and the critical values of the circumferential angles of contact losses, including:

[0021] S31. Preset the tunnel burial depth and the position of contact loss; set the first preset number of rings and the second preset number of rings, and the second preset number of rings is greater than or equal to the first preset number of rings;

[0022] S32. Set the longitudinal range of contact loss to the first preset number of rings;

[0023] S33. Gradually increase the circumferential angle of contact loss from zero, calculate the circumferential angle of contact loss when the tunnel structure is damaged, and obtain the critical value of the circumferential angle; record the tunnel burial depth, the position of contact loss, the longitudinal range of contact loss, and the critical value of the circumferential angle at this time as one level;

[0024] S34. Calculate the bending moment values at the joints between the rings and the joints within the rings covered by contact loss in the Euler-Lagrange model in real time, and judge whether there is a situation where the bending moment value is greater than its corresponding bearing capacity limit. If so, enter S35; otherwise, accumulate the second preset number of rings to the longitudinal range of the contact loss and enter S33;

[0025] S35. Change the tunnel burial depth and the position of contact loss, and repeat entering S32 until the tunnel burial depth and the position of contact loss are traversed.

[0026] Further, calculations are performed in the input judgment model, and the safety assessment result of the tunnel structure to be measured is output, including: judging the level corresponding to the tunnel burial depth, the position of contact loss, and the longitudinal range of contact loss, and then respectively judging whether the circumferential angle of each contact loss of the tunnel structure to be measured 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 determined that several segments of rings at the contact loss are in a non-safe state; otherwise, it is determined that several segments of rings at the contact loss are in a safe state.

[0027] In a second aspect, the present invention provides an evaluation system for the safety of tunnel linings, including the following modules:

[0028] Simulation module: Obtain the design parameters of the tunnel structure, and construct an Euler-Lagrange model according to the design parameters; respectively change each model parameter in the Euler-Lagrange model, and calculate the critical value of the circumferential angle of contact loss when the tunnel structure is damaged; the model parameters include the tunnel burial depth, the position of contact loss, and the longitudinal range of contact loss;

[0029] Model construction module; connected to the simulation module, and used to construct a judgment model according to different model parameters and the corresponding critical values of the circumferential angles; the judgment model is used to input each model parameter and output the safety assessment result of the tunnel structure;

[0030] Evaluation module: Connected to the model construction module, it is 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 measured, input them into the judgment model, and output the safety evaluation result of the tunnel structure to be measured.

[0031] In a third aspect, the present invention provides an electronic device, which includes: a processor and a memory; the processor is used to execute the steps of the method in the first aspect by calling the program or instruction stored in the memory.

[0032] The embodiments of the present invention have the following technical effects:

[0033] In this application, by constructing an Euler-Lagrange model, relevant parameters generated by contact loss around the tunnel structure are obtained, namely, the tunnel burial depth, contact loss position, and longitudinal range of contact loss; among them, each parameter is directly related to the safety of the tunnel structure. A relationship is established between each parameter and the safety of the tunnel structure, a judgment model is obtained by dividing grades according to each parameter, and then the safety of the tunnel structure to be measured is determined according to the grade corresponding to the parameters of the tunnel structure to be measured, which greatly reduces the complexity of data processing, improves the data processing efficiency and accuracy, and ensures the accuracy of the judgment result.

[0034] This application provides an effective safety evaluation system for the tunnel operation stage to monitor the safety status of the tunnel in real time. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained according to these drawings.

[0036] Figure 1 It is a flowchart of a method for evaluating the safety of a tunnel lining provided by an embodiment of the present invention;

[0037] Figure 2 It is a schematic structural diagram of an Euler-Lagrange model provided by an embodiment of the present invention;

[0038] Figure 3 It is a schematic cross-sectional view of a tunnel structure provided by an embodiment of the present invention;

[0039] Figure 4 It is a schematic diagram of the position of contact loss provided by an embodiment of the present invention;

[0040] Figure 5It is a schematic diagram of the damage caused by contact loss provided by an embodiment of the present invention;

[0041] Figure 6 It is a schematic diagram of each level provided by an embodiment of the present invention. Detailed implementation manners

[0042] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope protected by the present invention.

[0043] Embodiment 1

[0044] First, it should be noted that in this application, the longitudinal direction represents the extending direction of the pipeline, and the circumferential direction represents the direction perpendicular to the extending direction of the pipeline.

[0045] Figure 1 It is a flowchart of a method for evaluating the safety of a tunnel lining provided by an embodiment of the present invention. Refer to Figure 1 , which specifically includes:

[0046] S1. Obtain the design parameters of the tunnel structure and construct an Euler-Lagrange model according to the design parameters.

[0047] The design parameters of the tunnel structure include the tunnel length, diameter, etc., and the data required in the model construction process can be obtained by oneself.

[0048] Based on the Euler-Lagrange coupling method, a numerical model is constructed. This method has good applicability in solving large-deformation geotechnical engineering problems. The specific settings of each part are as follows:

[0049] (1) Soil

[0050] As Figure 2 shown, 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 Eulerian materials. By setting Eulerian boundaries in the model, the soil within the predetermined Eulerian boundaries can flow through the boundaries and disappear, while the soil outside the boundaries is not affected. Gaps are created on the top surface of the soil and inside the tunnel to accommodate the soil with a certain displacement. The Mohr-Coulomb model is used to simulate the flow behavior of the soil. The parameter configuration of the soil is shown in Table 1. The boundaries of the soil are set to zero displacement boundary conditions. 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.

[0051] Table 1 Parameter Configuration of Soil and Segment

[0052]

[0053] (2) Tunnel Structure

[0054] Figure 2 The cylindrical structure in it is the constructed tunnel structure. The tunnel structure is modeled using Lagrangian grids. The tunnel structure consists of several segments of rings, and each segment of the ring is composed of several segments. The elastic model is used to simulate the stress conditions of each segment.

[0055] Exemplarily, according to the geometric dimensions of the shield tunnel commonly used in a certain city, each segment (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 segment of the ring is 1.2 meters, and the segment thickness 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 conditions of the segment. The parameters of the segment are shown in Table 1. The two ends of the tunnel structure where it is connected to the soil are set as zero displacement boundary conditions, so that the velocity in the vertical direction at the contact is zero.

[0056] The interaction between the soil and the tunnel structure is realized through the "general contact" algorithm based on the penalty contact method. The friction coefficient between the soil and the segment is 0.4, and the lateral earth pressure coefficient K 0 is set to 0.5. Based on kinetic energy, a time step of 2 seconds is used to make the entire system reach a stable state.

[0057] (3) Joint

[0058] 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 connecting pieces.

[0059] In the above constructed model, two adjacent segments of the same segment of the ring can be connected by 2 connecting pieces, defined as the circumferential joint; the adjacent rings are connected by the staggered joint assembly method. Assuming that OA is the position line, see Figure 3 , then the OA lines of the adjacent rings are not parallel. And two adjacent rings are connected by 16 connecting pieces, defined as the longitudinal joint. The connecting pieces can be bolts, evenly distributed in the joint, and just meet the actual requirements. This application does not make specific restrictions.

[0060] In the model, the joint is specifically realized by setting the Euler boundary surface, that is, each connecting piece.

[0061] (4) Contact Loss

[0062] In this application, by setting the disappearance of the soil within the contact loss range, contact loss is generated between the tunnel and the soil.

[0063] S2. Respectively change each model parameter in the Euler-Lagrange model, 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, the contact loss position, and the longitudinal range of the contact loss.

[0064] First, after a 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 actual range of the contact loss is slightly larger than the predetermined range.

[0065] (1) Contact loss position

[0066] Exemplarily, the tunnel loss position is often divided into three parts, see Figure 4 , which are the tunnel bottom, the tunnel top, and the tunnel waist respectively. If the tunnel losses are set the same, only with the difference in position, the damage effects on the tunnel structure when the tunnel losses in each part act are different.

[0067] In this application, the relevant parameters related to the contact loss can be obtained and calculated through devices such as radar, which are all prior arts and will not be elaborated in this application.

[0068] (2) Tunnel burial depth

[0069] When the contact loss is located below the tunnel floor, the deformation development modes of tunnels with different tunnel burial depths are the same, but as the contact loss develops, the deformation of the tunnel with a larger overburden depth is more severe.

[0070] Exemplarily, the range of the tunnel burial depth is from 0 to 20 meters. In numerical simulations, the tunnel burial depth is often set as a multiple of the tunnel diameter.

[0071] Through 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, it is expressed in units of the outer diameter D of the tunnel structure. The soil pressure acting on the first group is less than that of the second group, making the uneven load of the contact loss acting on the tunnel structure greater. As the contact loss further develops, the deformation of the tunnel structure in the second group is more obvious.

[0072] It should be noted that the tunnel burial depth in this application refers to the distance from the top of the tunnel structure to the ground, and this data can be directly obtained according to the design drawings of the tunnel, etc.

[0073] (3) Longitudinal range of contact loss

[0074] 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 through the aforementioned devices such as radar.

[0075] First, the relevant influence of contact loss on the deformation of the tunnel structure is described:

[0076] In a specific embodiment, the outer diameter of the tunnel is D. Assuming the overburden depth of the tunnel is 2D, 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 two and a half rings.

[0077] 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 and represented by the degree of the circumferential angle corresponding to the tunnel structure.

[0078]

[0079] A total of four rings from the 1st ring to the 4th ring are set, and the contact loss covers the bottom of the 1st ring to the 3rd ring. After calculation, before and after the formation of each level of contact loss, the changes in the horizontal diameter and vertical diameter of the rings relative to their initial states are compared. As the contact loss develops, the vertical diameter of the rings within the contact loss range (i.e., the 1st ring to the 3rd ring) increases, and the horizontal diameter decreases. Before the formation of the contact loss, the soil pressure acting on each ring is similar to an annular force, restricting the deformation of the 1st ring to the 3rd ring. After the contact loss is formed under the tunnel, the annular effect of the soil pressure disappears, and the rings will deform. Due to the action of the soil pressure, the rings will be squeezed due to the contact loss.

[0080] For the 4th ring outside the contact loss range, when the circumferential angle corresponding to the contact loss is less than 30°, the change amount of its diameter increases; while when the circumferential angle corresponding to the contact loss exceeds 30°, the change amount of its diameter decreases. However, the change amount of the diameter of the 4th ring is limited, indicating that the contact loss has an obvious influence on the rings within its range.

[0081] Describe the influence of contact loss on the joints:

[0082] As the contact loss develops, each joint gradually fails. First, it is described that the longitudinal joints are mainly shear failures, while the circumferential joints mainly include shear failures and bending failures. Shear failure and bending failure are two basic failure modes in structural mechanics.

[0083] Based on the settings of the foregoing parameters, further experiments are carried out. See Figure 5When the contact loss develops to the third level, the three longitudinal joints between the second and fourth rings first undergo shear failure. As the contact loss develops, the third ring deforms towards the direction of the contact loss; however, the influence of the contact loss on the fourth ring is limited; therefore, the misalignment between the third and fourth rings increases, especially at the bottom plate position of the rings, and the longitudinal joint between the third and fourth rings should first fail.

[0084] After the contact loss develops to the fourth level, all 19 failed longitudinal joints exhibit shear failure, and 9 of these longitudinal joints are located between the third and fourth rings. Since the rings are assembled by means of staggered connections, there is no difference in the deformation of adjacent rings, and the misalignment between the rings simultaneously causes the failure of the circumferential joints. Eight circumferential joints of the first to third rings undergo bending failure due to excessive deformation of the rings.

[0085] In addition, three circumferential joints at the bottom plate position of the first to third rings undergo shear failure. The rings are assembled by the method of staggered connection, so the joints at the bottom plate position are also misaligned. At this time, almost half of the longitudinal joints between the third and fourth rings fail, and the connection between the two rings is weakened accordingly. The influence of the contact loss on the fourth ring is transmitted through the longitudinal joint between the third and fourth rings, and after the connection is weakened, the influence of the contact loss on the fourth ring almost disappears, further indicating that the contact loss only has an obvious influence on the rings within its range.

[0086] When the range of the contact loss continues to increase to the fifth level, the four circumferential joints that underwent bending failure at the previous level in the first to third rings also undergo shear failure, and one circumferential joint in the third ring undergoes both bending and shear failure simultaneously.

[0087] In summary, when the contact loss develops within a certain range, within this range, the safety of the tunnel structure will be significantly affected.

[0088] The following analyzes the relevant parameters of the contact loss to obtain the correlation between safety and each parameter:

[0089] Based on the above settings of parameters, structure, etc., expressed in terms 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 circumferential angle is 30°, that is, the degree value of the central angle corresponding to the covered tunnel structure. When it is greater than this degree, the tunnel structure deforms severely and the tunnel is in an unsafe state. Similarly, under the condition of a 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 circumferential angle is also 30°; when the contact loss is located at the tunnel top and the longitudinal range of the contact loss is 2.5 rings, the critical value of its circumferential 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 circumferential angle is 15°. Therefore, by changing the tunnel burial depth and the position of the contact loss, the critical value of the circumferential angle corresponding to each contact loss in the safe state can be uniquely obtained.

[0090] By further changing the tunnel burial depth, the position of the contact loss, and the longitudinal range of the 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 a circumferential angle of 90°, and when the circumferential angle of the contact loss approaches 90°, the soil around the contact loss will collapse, thus affecting the calculation results.

[0091] Figure 6 The circumferential angles of the 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 the contact loss does not exist, that is, during the development of the contact loss, the tunnel structure will not fail.

[0092] When the contact loss forms at different positions outside the tunnel and the longitudinal ranges of the contact loss are the same, the critical values of the circumferential angles of the contact loss are different. As the longitudinal range of the 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 tunnel top, the critical value of its circumferential angle also decreases from 45° to 30°. When the tunnel burial depth is 4D and the contact loss is located below the tunnel floor, as the longitudinal range of the 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 the tunnel contact loss increases to a certain value, the critical value of the circumferential angle of the contact loss decreases to the minimum value and does not decrease further.

[0093] When the tunnel burial depth is 4D, the variation pattern of the critical size of the contact loss with the longitudinal range of the contact loss is the same as that when the tunnel burial depth is 2D. However, when the tunnel burial depth is 4D, the critical value of the circumferential angle of the contact loss is smaller than that when the tunnel burial depth is 2D. Under the condition of a 4D tunnel burial 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 when the tunnel burial depth is 2D and the longitudinal range of the contact loss is 3.5 rings.

[0094] As the longitudinal range of the 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 the contact loss increases. When the longitudinal range of the contact loss reaches a certain level, its critical value will no longer change. As the longitudinal range of the contact loss expands, the critical value of the circumferential angle remains at 30°. That is, when the circumferential angle of the contact loss is less than 30°, the longitudinal range of the contact loss will not affect the safety of the tunnel structure.

[0095] In summary, once the contact loss reaches the critical value of the circumferential angle, the deformation of the tunnel will cause the joints to start to fail, thus affecting the safety of the entire tunnel structure; if the circumferential angle of the contact loss is less than the critical value, it indicates that the tunnel structure is temporarily in a safe state. Therefore, by establishing the relationship between the critical value of the circumferential angle, the tunnel burial depth, the location of the contact loss, the longitudinal range of the contact loss, and the tunnel safety, and obtaining each parameter, the conclusion of whether the tunnel is safe can be directly obtained.

[0096] S3. Construct a judgment model according to different model parameters and the corresponding critical values of the circumferential angle; the judgment model is used to input each model parameter and output the safety evaluation result of the tunnel structure.

[0097] The judgment model is: different levels are established according to different model parameter ranges and the critical values of the circumferential angle of the contact loss.

[0098] Specifically, the process of establishing the levels is as follows:

[0099] S31. Preset the tunnel burial depth and the location of the contact loss; set the first preset number of rings and the second preset number of rings, and the second preset number of rings is greater than or equal to the first preset number of rings.

[0100] S32. Set the longitudinal range of the contact loss to the first preset number of rings.

[0101] Exemplarily, in the simulation of this application, refer to Figure 6 , only half of the contact loss is considered. Therefore, the first preset number of rings is set to 0.5 ring. The first preset number of rings can be set according to the actual situation and can be regarded as the minimum unit of the longitudinal range of the contact loss.

[0102] S33. Gradually increase the circumferential angle of the contact loss from zero, calculate the circumferential angle of the contact loss when the tunnel structure is damaged, and obtain the critical value of the circumferential angle; record the tunnel burial depth, the position of the contact loss, the longitudinal range of the contact loss, and the critical value of the circumferential angle at this time as one level.

[0103] S34. Calculate the bending moment values at each circumferential joint and in-ring joint covered by the contact loss in the Euler-Lagrange model in real time, 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, accumulate the longitudinal range of the contact loss by a second preset number of rings and enter S33.

[0104] The second preset number of rings is set to 1 ring to ensure traversing one ring by one ring without omission, and it should be noted that during the development of the contact loss, the tunnel structure does not fail.

[0105] The circumferential joint is the part close to each other between the segments on the ring, and the in-ring joint is the part close to each other between the rings. When the bending moment values at each circumferential joint and in-ring joint in real time are greater than their corresponding bearing capacity limits, it indicates that the connection is damaged and the tunnel is in an unsafe state; otherwise, it indicates that the tunnel is still in a safe state.

[0106] Specifically, the bearing capacity limit of the in-ring joint is calculated by the following method:

[0107] Obtain the axial force and bending moment values at each in-ring joint on the ring covered by the contact loss in the Euler-Lagrange model respectively. When the inner side of the in-ring joint is in tension and the outer side is in compression, the bending moment is a positive bending moment value; when the outer side is in compression and the inner side is in tension, the bending moment is a negative bending moment value. It can be simply judged according to the connection situation of the inner and outer sides. For example, if the inner side is separated, it means the inner side is in tension and is a positive bending moment; if the outer side is separated, it means the outer side is in tension and is a negative bending moment.

[0108] In one embodiment, at a certain in-ring joint, when shear failure or bending failure begins to occur, a polynomial form about the axial force of the in-ring joint is used to fit the positive bending moment ultimate bearing capacity to simplify the curve expression. Through fitting, the relationship between the positive bending moment ultimate bearing capacity of the in-ring joint and the axial force is:

[0109] ,

[0110] where F is the axial force.

[0111] In one embodiment, at a certain circumferential joint, when shear failure or bending failure begins to occur, a polynomial form about the axial force of the in-ring joint is used to fit the negative bending moment ultimate bearing capacity to simplify the curve expression. Through fitting, the relationship between the negative bending moment ultimate bearing capacity of the in-ring joint and the axial force is:

[0112] ,

[0113] In fact, a tenon and mortise structure is provided in the circumferential joint. The force condition of the circumferential joint will cause the circumferential joint to be misaligned. When the inside of the segment where the mortise is located is subjected to the shearing action of the tenon, the bearing capacity is relatively low, and it is used as the bearing capacity limit M 3 , which can be calculated by the following formula:

[0114] .

[0115] 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 forces at each circumferential joint and the circumferential joint inside the ring, so as to obtain the magnitude relationship between the real-time bending moment value and its corresponding bearing capacity limit.

[0116] S35. Change the tunnel burial depth and the position of contact loss, and repeat to enter S32 until the tunnel burial depth and the position of contact loss are traversed.

[0117] For the longitudinal range of the tunnel burial depth and contact loss, the settings of each level value can be determined according to local standards, experience and different working conditions, and the present application does not make any limitations.

[0118] See Figure 6 For the divided levels, when the tunnel burial depth is less than or equal to 2D, the position of contact loss is at the waist, and the longitudinal range of contact loss is greater than 1.5 and less than or equal to 2.5 rings, and the circumferential angle is greater than or equal to 30°, it is one level, and the corresponding tunnel structure is in a non-safe state at this time; for another example, when the tunnel burial depth is greater than 2D and less than or equal to 4D, the position of contact loss is at the bottom, and the longitudinal range of 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 one level, and the corresponding tunnel structure is in a non-safe state at this time. The same is true for other levels, and they will not be elaborated here one by one. By setting different levels for comparison, the calculation amount is greatly reduced, and the accuracy of the evaluation result is ensured, and it is easier to perform the safety evaluation of the tunnel structure in real time.

[0119] S4. Obtain the tunnel burial depth, the position of contact loss, the longitudinal range of each contact loss and the circumferential angle of each contact loss of the tunnel structure to be measured, and input them into the judgment model for calculation, and output the safety evaluation result of the tunnel structure to be measured.

[0120] Specifically, determine the levels corresponding to the tunnel burial depth, the position of the contact loss, and the longitudinal range of the contact loss, and then respectively determine whether the circumferential angles of each contact loss of the tunnel structure to be measured are greater than or equal to the critical value of the circumferential angle corresponding to the corresponding level; if it is greater than or equal to the critical value of the circumferential angle corresponding to the corresponding level, it is determined that several segments of the ring at the contact loss are in a non-safe state; otherwise, it is determined that several segments of the ring at the contact loss are in a safe state. Exemplarily, when the tunnel burial depth is 2D, the contact loss position is at the top, and the longitudinal range of the contact loss is 2, if the circumferential angle is 45°, it is greater than the critical value of the circumferential angle, then the tunnel structure at this place is in an unsafe state, and structural cracking or other situations may have occurred, and maintenance is required; if the circumferential angle is 20°, it is considered that the tunnel structure at this place is in a safe state.

[0121] Based on the above technical solution, the present application provides an effective safety assessment system for the tunnel operation stage to monitor the safety state of the tunnel in real time.

[0122] Embodiment 2

[0123] Based on the content of Embodiment 1, the present application provides an assessment system for the safety of tunnel linings, including:

[0124] Simulation module: Obtain the design parameters of the tunnel structure, and construct an Euler-Lagrange model according to the design parameters; respectively change each model parameter in the Euler-Lagrange model, and calculate the critical value of the circumferential angle of the contact loss when the tunnel structure is damaged; the model parameters include the tunnel burial depth, the contact loss position, and the longitudinal range of the contact loss;

[0125] Model construction module; connected to the simulation module, used to construct a judgment model according to different model parameters and the corresponding critical values of the circumferential angles; the judgment model is used to input each model parameter and output the safety assessment result of the tunnel structure;

[0126] Assessment module: Connected to the model construction module, used to obtain 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 tunnel structure to be measured, and input them into the judgment model to output the safety assessment result of the tunnel structure to be measured.

[0127] For other content, see Embodiment 1, and no further elaboration will be made here.

[0128] Embodiment 3

[0129] 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 Embodiment 1 by calling the program or instruction stored in the memory.

[0130] 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 foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate 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, obtaining 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 inputting them into the judgment model, and outputting the safety assessment result of the tunnel structure to be tested; The judgment model is: different levels are established according to different model parameter ranges and critical values ​​of the contact loss circumferential angle; 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; 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.

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 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 4, 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.

6. 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 4 by calling the program or instruction stored in the memory.

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