A health monitoring and early warning method and system for tunnels crossing active faults during operation

Abstract

The present application provides a method and system for health monitoring and early warning during the operation of a tunnel crossing an active fault, which relates to the field of tunnel monitoring technology. The method includes: measuring the fault slip and displacement pattern of a tunnel crossing an active fault and performing finite element numerical simulation to obtain finite element numerical simulation results; collecting monitoring data of the tunnel crossing an active fault through a determined control index, and conducting engineering verification of the finite element numerical simulation results, and adjusting the parameters of the finite element numerical simulation results; obtaining the basic physical and mechanical parameters of the tunnel, combining the tunnel structure evaluation method, obtaining a reinforced concrete bearing capacity characteristic curve, and determining the early warning threshold of the tunnel structure; combining the collected monitoring data, the adjusted finite element numerical simulation results, and the early warning threshold to obtain the early warning result of the tunnel structure crossing an active fault. The technical solution of the present application can improve the accuracy of the early warning results.

Description

Technical Field

[0001] The present application relates to the field of tunnel monitoring technology, and in particular to a health monitoring and early warning method and system for a tunnel crossing an active fault during operation. Background Art

[0002] Many highway, railway, and water diversion tunnels inevitably cross active fault zones. Continuous creep and slippage in these zones can severely damage the tunnel lining during operation and pose a serious threat to personnel safety. Displacement in fault zones is often irregular, with distinct variations at different locations.

[0003] Therefore, it is very necessary to understand the movement of active faults and their impact on tunnels. This is an important scientific issue that cannot be avoided in engineering research, design and operation, and it is also an important technical issue that needs to be urgently solved in the construction of transportation tunnels crossing active faults in the west.

[0004] Accurately identifying the displacement and distribution patterns of active faults is crucial for selecting engineering measures and operating tunnel structures. Fault displacement is typically monitored using laser rangefinders, observatories, GNSS, or deep-hole displacement monitoring. However, currently, there is no reliable method for identifying the displacement and distribution patterns along the thickness of active faults during tunnel operation.

[0005] Corresponding tunnel structure safety assessment and early warning methods need further improvement. Therefore, a highly sensitive, simple, rapid, and stable tunnel monitoring and early warning method is urgently needed. Furthermore, the application of a method that combines numerical simulation, monitoring feedback, model modification, theoretical derivation, and engineering verification in tunnel structure monitoring and early warning needs to be further improved. Summary of the Invention

[0006] The purpose of the present invention is to provide a health monitoring and early warning method and system for tunnels crossing active faults during operation in order to solve the problem that existing tunnel monitoring and early warning methods cannot accurately monitor and warn tunnel structures.

[0007] The above-mentioned purpose of this application is achieved through the following technical solutions:

[0008] S1: Measure the fault displacement and displacement pattern of a tunnel crossing an active fault;

[0009] S2: The fault dislocation and displacement pattern are input as boundary conditions, combined with the concrete damage plasticity model, to perform a three-dimensional stratum-structure method finite element numerical simulation to obtain the finite element numerical simulation results;

[0010] S3: Collect monitoring data based on the control indicators of tunnels crossing active faults; the control indicators include bending moment, axial force, and convergence deformation of the tunnel structure;

[0011] S4: Conduct engineering verification of the finite element numerical simulation results through the collected monitoring data and adjust the parameters of the finite element numerical simulation results;

[0012] S5: Obtain the basic physical and mechanical parameters of the tunnel, combine them with the tunnel structure evaluation method, obtain the reinforced concrete bearing capacity characteristic curve, and determine the early warning threshold of the tunnel structure;

[0013] S6: Combining the collected monitoring data, the adjusted finite element numerical simulation results and the warning threshold, the warning results of the tunnel structure crossing the active fault are obtained.

[0014] Optionally, step S5 includes:

[0015] Determine the stress mode of reinforced concrete rectangular section; the stress mode includes: first stress mode, second stress mode and third stress mode;

[0016] By combining the load-bearing mode and basic physical and mechanical parameters with the calculation formulas for the strength of reinforced concrete bending members, the calculation formulas for the cross-sectional strength of members subjected to large eccentricity and the calculation formulas for the cross-sectional strength of members subjected to small eccentricity, the characteristic curves of the bearing capacity of reinforced concrete under different load-bearing modes are obtained.

[0017] Determine the warning threshold of the tunnel structure through the reinforced concrete bearing capacity characteristic curve;

[0018] The warning thresholds include: a first warning threshold, a second warning threshold, and a third warning threshold.

[0019] Optionally, the calculation formula for the strength of the reinforced concrete flexural member is as follows:

[0020]

[0021] in, represents the safety factor; represents the bending moment; It represents the ultimate compressive strength of concrete; Indicates the width of the rectangular cross section; Indicates the height of the concrete compression zone; Indicates the standard value of tensile or compressive strength of steel bars; Represents the cross-sectional area of ​​the steel bars in the compression zone; Indicates the effective height of the section; It represents the distance from the center of gravity of the tension reinforcement or compression reinforcement to the nearest edge of the section respectively;

[0022] The calculation formula for the cross-sectional strength of a large eccentrically compressed member is as follows:

[0023]

[0024] in, represents the axial force; Represents the cross-sectional area of ​​the steel bars in the tension zone;

[0025] The calculation formula for the cross-sectional strength of a member subjected to small eccentricity is as follows:

[0026]

[0027] in It indicates the distance from the center of gravity of the tensile or compressive reinforcement to the point of application of the axial force.

[0028] Optionally, the first stress mode of the reinforced concrete rectangular section is as follows:

[0029] when hour;

[0030] Let the safety factor K=1 for the calculation formula of the strength of reinforced concrete flexural members and the calculation formula of the cross-sectional strength of members subjected to large eccentricity;

[0031] According to the cross-sectional strength of the large eccentrically compressed member,

[0032]

[0033] Substitute formula (1) into the strength calculation formula of reinforced concrete bending members, and the tunnel structure have to

[0034]

[0035] At the same time, M should meet the following conditions:

[0036]

[0037] Input the basic physical and mechanical parameters into equations (2) and (3) to obtain the reinforced concrete bearing capacity characteristic curve under the first load mode and determine the first warning threshold.

[0038] Optionally, the second load mode of the reinforced concrete rectangular section is as follows: When the tensile zone of the component is damaged, the main consideration is that the tensile zone of the component is damaged;

[0039] Known , ,in Indicates the distance from the neutral axis to the point of action of the axial force; Indicates the section height;

[0040] The calculation formula of cross-sectional strength of small eccentrically compressed members is The safety factor K is 1, so we can get

[0041]

[0042] At the same time, M and N should meet the following conditions:

[0043]

[0044] Input the basic physical and mechanical parameters into equations (4) and (5) to obtain the characteristic curve of reinforced concrete bearing capacity under the second stress mode and determine the second warning threshold.

[0045] Optionally, the third stress mode of the reinforced concrete rectangular section is as follows:

[0046] when When , the main consideration is that the compression area of ​​the component is crushed;

[0047] The calculation formula for the cross-sectional strength of reinforced concrete rectangular cross-section members subjected to small eccentric compression is The safety factor K is 1, and it is known that , ;

[0048] From this we can get

[0049]

[0050] in Indicates the compressive strength of concrete;

[0051] Input the basic physical and mechanical parameters into formula (6) to obtain the reinforced concrete bearing capacity characteristic curve under the third stress mode and determine the third warning threshold.

[0052] A health monitoring and early warning system for a tunnel crossing an active fault during operation, the system comprising: an axial array displacement meter, a circumferential array displacement meter, a steel bar stress gauge, a concrete strain gauge, and a processing module;

[0053] The axial array displacement meter is used to measure the fault displacement and displacement pattern of the fault passing through the active fault tunnel;

[0054] The circumferential array displacement meter is used to measure the convergence deformation of the tunnel structure;

[0055] The steel bar stress gauge is used to monitor stress; the concrete strain gauge is used to monitor strain;

[0056] Monitoring data include: stress, strain, and convergence deformation of the tunnel structure;

[0057] The processing module is used to input the fault dislocation and the dislocation displacement mode as boundary conditions, and perform a three-dimensional stratum-structure method finite element numerical simulation in combination with a concrete damage plasticity model to obtain a finite element numerical simulation result;

[0058] The processing module is further used to calculate the bending moment and axial force of the tunnel structure through stress and strain;

[0059] The processing module is further used to perform engineering verification on the finite element numerical simulation results through bending moment, axial force and convergence deformation, and adjust the parameters of the finite element numerical simulation results;

[0060] The processing module is also used to obtain basic physical and mechanical parameters of the tunnel, and in combination with the tunnel structure evaluation method, obtain a characteristic curve of the reinforced concrete bearing capacity to determine the early warning threshold of the tunnel structure;

[0061] The processing module is further used to combine the collected monitoring data, the adjusted finite element numerical simulation results and the warning threshold to obtain a warning result of the tunnel structure crossing the active fault.

[0062] Optionally, the axial array displacement meter is arranged at the left and right arch waist positions of the tunnel; the axial array displacement meter is arranged between the initial support and the surrounding rock, and both ends of the axial array displacement meter pass through the active fault for a preset distance;

[0063] Two tunnel sections were selected at the preset location of the active fault, and the circumferential array displacement meter was symmetrically arranged from the left arch foot of the tunnel section to the right arch foot of the same tunnel section along the circumferential direction.

[0064] Steel bar stress gauges and concrete strain gauges are arranged inside and outside the secondary lining steel mesh of two selected tunnel sections, specifically: steel bar stress gauges and concrete strain gauges are set at the left and right arch haunches, left and right arch spandrels and arch crown positions of the secondary lining of each tunnel section.

[0065] The beneficial effects of the technical solution provided by this application are:

[0066] 1. The use of circumferential and axial array displacement meters accurately measures the magnitude and pattern of displacement along active faults surrounding the tunnel, providing a basis for understanding the impact of active fault zone dislocation on the tunnel structure. Finite element numerical simulations of tunnels crossing active faults allow for parameter correction based on on-site monitoring data of tunnel deformation and secondary lining stress, making the simulation results more consistent with engineering practice. Furthermore, finite element numerical simulations of tunnels crossing active faults overcome the limitation of on-site tunnel monitoring, which can only be performed on typical sections. The theoretical limits of bending moments and axial forces that tunnel structures can withstand under compressive and bending loads are derived, forming a structural evaluation method—a reinforced concrete bearing capacity characteristic curve. This allows for targeted and effective early warning of the tunnel structure's health, resulting in a simple and reasonable assessment method. The integration of numerical simulation, monitoring feedback, model correction, theoretical derivation, and engineering verification results in more reasonable early warning results for tunnel structures. These methods complement each other and work together to ensure the safety and quality of tunnel projects.

[0067] 2. A health monitoring and early warning method for tunnels crossing active faults during operation is proposed to accurately measure the size and pattern of fault displacements around the tunnel. A structural evaluation method for mountain tunnels, namely the reinforced concrete bearing capacity characteristic curve, is proposed. By monitoring the stress and strain of reinforced concrete in typical sections, the accuracy and feasibility of the numerical simulation results under the fault displacement model are verified. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] The present application will be further described below with reference to the accompanying drawings and embodiments, in which:

[0069] Figure 1 is a flow chart in an embodiment of the present application;

[0070] Figure 2 Schematic diagram of the layout of the monitoring array displacement meter in the embodiment of the present application;

[0071] Figure 3 1 is a top view of the arrangement of the monitoring array displacement meter in an embodiment of the present application;

[0072] Figure 4 This is a layout diagram of the annular array displacement meter, concrete strain gauge, and steel bar stress gauge in the embodiment of the present application;

[0073] Figure 5 is a schematic structural diagram of a finite element model in an embodiment of the present application;

[0074] Figure 6 is a flow chart for calculating the bearing capacity of reinforced concrete under compression and bending loads in an embodiment of the present application;

[0075] Figure 7 1 is a diagram showing the stress condition of reinforced concrete under compression-bending load in the first stress mode in the embodiment of the present application;

[0076] Figure 8 This is a diagram showing the stress condition of reinforced concrete under compression-bending load in the third stress mode in the embodiment of the present application;

[0077] Figure 9 is a characteristic curve diagram of the reinforced concrete bearing capacity under the first stress mode in the embodiment of the present application;

[0078] Figure 10 is a characteristic curve diagram of the reinforced concrete bearing capacity under the second stress mode in the embodiment of the present application;

[0079] Figure 11 It is a schematic diagram of the characteristic curve of the reinforced concrete bearing capacity under the third stress mode in the embodiment of the present application. DETAILED DESCRIPTION

[0080] In order to have a clearer understanding of the technical features, purposes and effects of this application, the specific implementation methods of this application are now described in detail with reference to the accompanying drawings.

[0081] The embodiments of the present application provide a health monitoring and early warning method for a tunnel crossing an active fault during operation.

[0082] Please refer to Figure 1 , Figure 1 This is a flow chart of a health monitoring and early warning method for a tunnel crossing an active fault during operation according to an embodiment of the present application, including:

[0083] S1: Measure the fault displacement and displacement pattern of a tunnel crossing an active fault;

[0084] S2: The fault dislocation and displacement pattern are input as boundary conditions, combined with the concrete damage plasticity model, to perform a three-dimensional stratum-structure method finite element numerical simulation to obtain the finite element numerical simulation results;

[0085] In some embodiments, the concrete damage plasticity model (CDP) in ABAQUS finite element analysis software is a constitutive model based on plasticity and damage mechanics that can simulate the nonlinear behavior of concrete under complex loads, including characteristics such as tensile cracking, compressive crushing, stiffness degradation, and irreversible plastic deformation.

[0086] In some embodiments, the amount of fault displacement monitored by the array displacement meter is small, but the displacement pattern is clear. When used as a boundary condition input, the displacement pattern uses the monitoring data, while the fault displacement is increased in a certain proportion. Setting multiple fault displacement conditions with different displacement amounts and applying them to the boundary provides a certain degree of predictability.

[0087] In some embodiments, finite element numerical simulation can obtain the full-dimensional stress and deformation conditions of the tunnel, and can extract bending moments, axial forces, etc. in multiple sections and multiple working conditions, so as to provide multi-position and multi-state early warning for the tunnel.

[0088] S3: Collect monitoring data based on the control indicators of tunnels crossing active faults; the control indicators include bending moment, axial force, and convergence deformation of the tunnel structure;

[0089] S4: Conduct engineering verification of the finite element numerical simulation results through the collected monitoring data and adjust the parameters of the finite element numerical simulation results;

[0090] S5: Obtain the basic physical and mechanical parameters of the tunnel, combine them with the tunnel structure evaluation method, obtain the reinforced concrete bearing capacity characteristic curve, and determine the early warning threshold of the tunnel structure;

[0091] S6: Combining the collected monitoring data, the adjusted finite element numerical simulation results and the warning threshold, the warning results of the tunnel structure crossing the active fault are obtained.

[0092] Step S5 includes:

[0093] Determine the stress mode of reinforced concrete rectangular section; the stress mode includes: first stress mode, second stress mode and third stress mode;

[0094] By combining the load-bearing mode and basic physical and mechanical parameters with the calculation formulas for the strength of reinforced concrete bending members, the calculation formulas for the cross-sectional strength of members subjected to large eccentricity and the calculation formulas for the cross-sectional strength of members subjected to small eccentricity, the characteristic curves of the bearing capacity of reinforced concrete under different load-bearing modes are obtained.

[0095] Determine the warning threshold of the tunnel structure through the reinforced concrete bearing capacity characteristic curve;

[0096] The warning thresholds include: a first warning threshold, a second warning threshold, and a third warning threshold.

[0097] As an example, Figure 6 The calculation process of reinforced concrete bearing capacity under compression and bending load is shown. According to formulas (1) to (6), the basic physical and mechanical parameters (concrete bending compressive ultimate strength , the width of the rectangular cross section etc.), combined Figure 7 and Figure 8 The stress conditions of reinforced concrete under different compression and bending load conditions can be obtained Figures 10 and 11 Characteristic curve of reinforced concrete bearing capacity for a specific tunnel example.

[0098] As an embodiment, the present invention provides a method for monitoring the health of a tunnel crossing an active fault during operation, which measures the annular reinforcement stress and concrete strain of the secondary lining, the tunnel convergence deformation, the magnitude of the fault dislocation and the dislocation displacement pattern.

[0099] The calculation formula for the strength of reinforced concrete flexural members is as follows:

[0100]

[0101] in, represents the safety factor; represents the bending moment; It represents the ultimate compressive strength of concrete; Indicates the width of the rectangular cross section; Indicates the height of the concrete compression zone; Indicates the standard value of tensile or compressive strength of steel bars; Represents the cross-sectional area of ​​the steel bars in the compression zone; Indicates the effective height of the section; It represents the distance from the center of gravity of the tension reinforcement or compression reinforcement to the nearest edge of the section respectively;

[0102] The calculation formula for the cross-sectional strength of a large eccentrically compressed member is as follows:

[0103]

[0104] in, represents the axial force; Represents the cross-sectional area of ​​the steel bars in the tension zone;

[0105] The calculation formula for the cross-sectional strength of a member subjected to small eccentricity is as follows:

[0106]

[0107] in It indicates the distance from the center of gravity of the tensile or compressive reinforcement to the point of application of the axial force.

[0108] As an embodiment, the basic physical and mechanical parameters of the tunnel structure are shown in Table 1.

[0109] Table 1

[0110]

[0111] The first load mode of the reinforced concrete rectangular section is as follows:

[0112] when hour;

[0113] Let the safety factor K=1 for the calculation formula of the strength of reinforced concrete flexural members and the calculation formula of the cross-sectional strength of members subjected to large eccentricity;

[0114] According to the cross-sectional strength of the large eccentrically compressed member,

[0115]

[0116] Substitute formula (1) into the strength calculation formula of reinforced concrete bending members, and the tunnel structure have to

[0117]

[0118] At the same time, M should meet the following conditions:

[0119]

[0120] in The unit representing the physical quantity bending moment M.

[0121] Input the basic physical and mechanical parameters into equations (2) and (3) to obtain the reinforced concrete bearing capacity characteristic curve under the first load mode and determine the first warning threshold.

[0122] The second load mode of the reinforced concrete rectangular section is as follows: When the tensile zone of the component is damaged, the main consideration is that the tensile zone of the component is damaged;

[0123] Known , ,in Indicates the distance from the neutral axis to the point of action of the axial force; Indicates the section height;

[0124] The calculation formula of cross-sectional strength of small eccentrically compressed members is The safety factor K is 1, so we can get

[0125]

[0126] At the same time, M and N should meet the following conditions:

[0127]

[0128] Input the basic physical and mechanical parameters into equations (4) and (5) to obtain the characteristic curve of reinforced concrete bearing capacity under the second stress mode and determine the second warning threshold.

[0129] The third load mode of the reinforced concrete rectangular section is as follows:

[0130] when When , the main consideration is that the compression area of ​​the component is crushed;

[0131] The calculation formula for the cross-sectional strength of reinforced concrete rectangular cross-section members subjected to small eccentric compression is The safety factor K is 1, and it is known that , ;

[0132] From this we can get

[0133]

[0134] in Indicates the compressive strength of concrete;

[0135] Input the basic physical and mechanical parameters into formula (6) to obtain the reinforced concrete bearing capacity characteristic curve under the third stress mode and determine the third warning threshold.

[0136] A health monitoring and early warning system for a tunnel crossing an active fault during operation, the system comprising: an axial array displacement meter, a circumferential array displacement meter, a steel bar stress gauge, a concrete strain gauge, and a processing module;

[0137] In one embodiment, the array displacement meter consists of a multi-segment test unit, each composed of multiple standard segments connected by flexible links. It can measure displacement in three dimensions (X, Y, and Z) with a measurement accuracy of 0.1% FS. In some embodiments, the array displacement meter's test units can use standard segments of 0.5 meters or 1 meters per segment, and the total instrument length can be customized based on the fault width.

[0138] The axial array displacement meter is used to measure the fault displacement and displacement pattern of the fault passing through the active fault tunnel;

[0139] The circumferential array displacement meter is used to measure the convergence deformation of the tunnel structure;

[0140] The steel bar stress gauge is used to monitor stress; the concrete strain gauge is used to monitor strain;

[0141] Monitoring data include: stress, strain, and convergence deformation of the tunnel structure;

[0142] The processing module is used to input the fault dislocation and the dislocation displacement mode as boundary conditions, and perform a three-dimensional stratum-structure method finite element numerical simulation in combination with a concrete damage plasticity model to obtain a finite element numerical simulation result;

[0143] The processing module is further used to calculate the bending moment and axial force of the tunnel structure through stress and strain;

[0144] The processing module is further used to perform engineering verification on the finite element numerical simulation results through bending moment, axial force and convergence deformation, and adjust the parameters of the finite element numerical simulation results;

[0145] The processing module is also used to obtain basic physical and mechanical parameters of the tunnel, and in combination with the tunnel structure evaluation method, obtain a characteristic curve of the reinforced concrete bearing capacity to determine the early warning threshold of the tunnel structure;

[0146] The processing module is further used to combine the collected monitoring data, the adjusted finite element numerical simulation results and the warning threshold to obtain a warning result of the tunnel structure crossing the active fault.

[0147] The axial array displacement meter is arranged at the left and right arch waist positions of the tunnel; the axial array displacement meter is arranged between the initial support and the surrounding rock, and the two ends of the axial array displacement meter pass through the active fault for a preset distance;

[0148] As an embodiment, axial array displacement meters (array displacement meters along the axial direction) are arranged at the left and right arch waist positions of the tunnel; the axial array displacement meters are arranged between the initial support and the surrounding rock, and the two ends of the axial array displacement meter pass through the active fault for a preset distance, so as to accurately measure the magnitude of the fault displacement and the displacement pattern around the tunnel.

[0149] Two tunnel sections were selected at the preset location of the active fault, and the circumferential array displacement meter was symmetrically arranged from the left arch foot of the tunnel section to the right arch foot of the same tunnel section along the circumferential direction.

[0150] As an embodiment, for the circumferential array displacement meter, two typical tunnel sections crossing active faults are selected and symmetrically arranged along the circumference from the left arch foot to the right arch foot to monitor the convergence deformation of the tunnel structure caused by the fault dislocation.

[0151] In some embodiments, reference Figure 2 and Figure 3 In this embodiment, the test unit of the array displacement meter adopts a standard segment of 1 meter per section, and each standard segment is connected by a flexible link. Each standard segment requires 2 fixed points. The axial array displacement meter is arranged at the left and right arch waist positions of the tunnel, between the initial support and the surrounding rock through a fixed point composed of expansion screws and a base, and the two ends of the displacement meter pass through the active fault for a distance to accurately measure the size and mode of the fault displacement around the tunnel. Two typical tunnel sections at the interface between the fault and the general surrounding rock are selected, and the circumferential array displacement meter is installed section by section using the base, expansion screws and riding card. It is arranged symmetrically along the circumferential direction from the left arch foot to the right arch foot to monitor the convergence deformation of the tunnel structure caused by the fault displacement. After the axial and circumferential array displacement meters are installed, they can be stably operated for a period of time (48 hours is recommended) and the initial readings can be collected according to the requirements of the monitoring project.

[0152] Steel bar stress gauges and concrete strain gauges are arranged inside and outside the secondary lining steel mesh of two selected tunnel sections, specifically: steel bar stress gauges and concrete strain gauges are set at the left and right arch haunches, left and right arch spandrels and arch crown positions of the secondary lining of each tunnel section.

[0153] In some embodiments, reference Figure 4 Steel and concrete strain gauges were placed inside and outside the secondary lining reinforcement mesh, in the same locations as the two sections of the circumferential array displacement gauge. Each section was placed on the left and right haunches, left and right spandrels, and crown of the secondary lining. This was primarily to monitor changes in the secondary lining's internal forces.

[0154] Figure 5 is a schematic structural diagram of a finite element model in an embodiment of the present application; Figure 9It is a characteristic curve diagram of the reinforced concrete bearing capacity under the first stress mode in the embodiment of the present application.

[0155] The above are merely exemplary embodiments of the present disclosure and are not intended to limit the scope of the present disclosure. In other words, any equivalent changes and modifications made according to the teachings of the present disclosure are still within the scope of the present disclosure.

[0156] This application is intended to cover any variations, uses, or adaptations of the present disclosure that follow the general principles of the present disclosure and include common knowledge or customary techniques in the art not described herein. The description and examples are to be considered as exemplary only, and the scope and spirit of the present disclosure are to be defined by the claims.

Claims

1. A health monitoring and early warning method for a tunnel crossing an active fault during operation, characterized in that: The method comprises the following steps: S1: Measure the fault displacement and displacement pattern of a tunnel crossing an active fault; The axial array displacement meter is placed at the left and right arch waist positions of the tunnel; the axial array displacement meter is placed between the initial support and the surrounding rock, and the two ends of the axial array displacement meter pass through the active fault for a preset distance; Two tunnel sections were selected at the preset location of the active fault, and the circumferential array displacement meter was symmetrically arranged from the left arch foot of the tunnel section to the right arch foot of the same tunnel section along the circumferential direction. S2: The fault dislocation and displacement pattern are input as boundary conditions, combined with the concrete damage plasticity model, to perform a three-dimensional stratum-structure method finite element numerical simulation to obtain the finite element numerical simulation results; S3: Collect monitoring data based on the control indicators of tunnels crossing active faults; the control indicators include bending moment, axial force, and convergence deformation of the tunnel structure; S4: Conduct engineering verification of the finite element numerical simulation results through the collected monitoring data and adjust the parameters of the finite element numerical simulation results; S5: Obtain the basic physical and mechanical parameters of the tunnel, combine them with the tunnel structure evaluation method, obtain the reinforced concrete bearing capacity characteristic curve, and determine the early warning threshold of the tunnel structure; S6: Combining the collected monitoring data, the adjusted finite element numerical simulation results and the warning threshold, the warning results of the tunnel structure crossing the active fault are obtained.

2. The method for health monitoring and early warning during operation of a tunnel crossing an active fault according to claim 1, characterized in that: Step S5 includes: Determine the stress mode of reinforced concrete rectangular section; the stress mode includes: first stress mode, second stress mode and third stress mode; By combining the load-bearing mode and basic physical and mechanical parameters with the calculation formulas for the strength of reinforced concrete bending members, the calculation formulas for the cross-sectional strength of members subjected to large eccentricity and the calculation formulas for the cross-sectional strength of members subjected to small eccentricity, the characteristic curves of the bearing capacity of reinforced concrete under different load-bearing modes are obtained. Determine the warning threshold of the tunnel structure through the reinforced concrete bearing capacity characteristic curve; The warning thresholds include: a first warning threshold, a second warning threshold, and a third warning threshold.

3. The method for health monitoring and early warning during operation of a tunnel crossing an active fault according to claim 2, characterized in that: The calculation formula for the strength of reinforced concrete flexural members is as follows: in, represents the safety factor; represents the bending moment; It represents the ultimate compressive strength of concrete; Indicates the width of the rectangular cross section; Indicates the effective height of the section; Indicates the height of the concrete compression zone; Indicates the standard value of tensile or compressive strength of steel bars; Represents the cross-sectional area of ​​the steel bars in the compression zone; It represents the distance from the center of gravity of the tension reinforcement or compression reinforcement to the nearest edge of the section respectively; The calculation formula for the cross-sectional strength of a large eccentrically compressed member is as follows: in, represents the axial force; Represents the cross-sectional area of ​​the steel bars in the tension zone; The calculation formula for the cross-sectional strength of a member subjected to small eccentricity is as follows: in It indicates the distance from the center of gravity of the tensile or compressive reinforcement to the point of application of the axial force.

4. The method for health monitoring and early warning during operation of a tunnel crossing an active fault according to claim 3, characterized in that: The first load mode of the reinforced concrete rectangular section is as follows: when hour; Let the safety factor K=1 for the calculation formula of the strength of reinforced concrete flexural members and the calculation formula of the cross-sectional strength of members subjected to large eccentricity; According to the cross-sectional strength of the large eccentrically compressed member, Substitute formula (1) into the strength calculation formula of reinforced concrete bending members, and the tunnel structure have to At the same time, M should meet the following conditions: Input the basic physical and mechanical parameters into equations (2) and (3) to obtain the reinforced concrete bearing capacity characteristic curve under the first load mode and determine the first warning threshold.

5. The method for health monitoring and early warning during operation of a tunnel crossing an active fault according to claim 4, characterized in that: The second load mode of the reinforced concrete rectangular section is as follows: When the tensile zone of the component is damaged, the main consideration is that the tensile zone of the component is damaged; Known , ,in Indicates the distance from the neutral axis to the point of action of the axial force; Indicates the section height; The calculation formula of cross-sectional strength of small eccentrically compressed members is The safety factor K is 1, so we can get At the same time, M and N should meet the following conditions: Input the basic physical and mechanical parameters into equations (4) and (5) to obtain the characteristic curve of reinforced concrete bearing capacity under the second stress mode and determine the second warning threshold.

6. The method for health monitoring and early warning during operation of a tunnel crossing an active fault according to claim 5, characterized in that: The third load mode of the reinforced concrete rectangular section is as follows: when When , the main consideration is that the compression area of ​​the component is crushed; The calculation formula for the cross-sectional strength of reinforced concrete rectangular cross-section members subjected to small eccentric compression is The safety factor K is 1, and it is known that , ; From this we can get in Indicates the compressive strength of concrete; Input the basic physical and mechanical parameters into formula (6) to obtain the reinforced concrete bearing capacity characteristic curve under the third stress mode and determine the third warning threshold.

7. A health monitoring and early warning system for a tunnel crossing an active fault during operation, for implementing a health monitoring and early warning method for a tunnel crossing an active fault during operation as claimed in any one of claims 1 to 6, characterized in that: The system includes: an axial array displacement meter, a circumferential array displacement meter, a steel bar strain gauge, a concrete strain gauge and a processing module; The axial array displacement meter is used to measure the fault displacement and displacement pattern of the fault passing through the active fault tunnel; The circumferential array displacement meter is used to measure the convergence deformation of the tunnel structure; The steel bar stress gauge is used to monitor stress; the concrete strain gauge is used to monitor strain; Monitoring data include: stress, strain, and convergence deformation of the tunnel structure; The processing module is used to input the fault dislocation and the dislocation displacement mode as boundary conditions, and perform a three-dimensional stratum-structure method finite element numerical simulation in combination with a concrete damage plasticity model to obtain a finite element numerical simulation result; The processing module is further used to calculate the bending moment and axial force of the tunnel structure through stress and strain; The processing module is further used to perform engineering verification on the finite element numerical simulation results through bending moment, axial force and convergence deformation, and adjust the parameters of the finite element numerical simulation results; The processing module is also used to obtain basic physical and mechanical parameters of the tunnel, and in combination with the tunnel structure evaluation method, obtain a characteristic curve of the reinforced concrete bearing capacity to determine the early warning threshold of the tunnel structure; The processing module is further used to combine the collected monitoring data, the adjusted finite element numerical simulation results and the warning threshold to obtain a warning result of the tunnel structure crossing the active fault.

8. The health monitoring and early warning system for a tunnel crossing an active fault during operation as claimed in claim 7, characterized in that: Steel bar stress gauges and concrete strain gauges are arranged inside and outside the secondary lining steel mesh of two selected tunnel sections, specifically: steel bar stress gauges and concrete strain gauges are set at the left and right arch haunches, left and right arch spandrels and arch crown positions of the secondary lining of each tunnel section.

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