A method for searching a leakage path of a shield tunnel sealing gasket interface

Abstract

The application provides a shield tunnel sealing gasket interface leakage path search method, relates to the technical field of tunnel engineering health monitoring and safety evaluation, and comprises the following steps: establishing an interface contact pressure matrix according to the contact surface roughness of the sealing gasket; identifying potential leakage units by calculating the multi-factor leakage tendency index of each unit; identifying a potential leakage area based on anisotropic directional seepage tracking according to the identified potential leakage units; screening a complete leakage path based on the potential leakage area, calculating an equivalent hydraulic conductivity coefficient, determining the leakage risk level of the complete leakage path according to the equivalent hydraulic conductivity coefficient; visually displaying the complete leakage path and the leakage risk level thereof; evaluating the robustness level of the complete leakage path; and obtaining a repair decision. The application has the advantage that the safety of the whole life cycle of underground engineering can be improved.

Description

Technical Field

[0001] This invention relates to the field of tunnel engineering health monitoring and safety assessment technology, and more specifically, to a method for searching leakage paths at the interface of a shield tunnel sealing gasket. Background Technology

[0002] The waterproofing system of a shield tunnel consists of segment grouting, segment self-waterproofing, and joint waterproofing. Joint waterproofing is the last line of defense in this system and plays a crucial role in the safe operation of the tunnel. Leakage is prevented at the segment joints through the contact and compression of elastic rubber sealing gaskets between the segment rings (blocks).

[0003] Currently, in the design phase, gaskets are typically designed using numerical simulations to obtain interfacial contact stress results, with the average interfacial contact stress reflecting the gasket's waterproofing effect. However, this approach faces several new challenges. Firstly, it requires establishing a model that accurately reflects the surface characteristics of the elastic rubber gasket. The surface of an elastic rubber gasket is not ideally smooth; it typically exhibits complex geometric shapes. At the joint of pipe segments, the rubber gasket undergoes elastic deformation under assembly force, generating normal contact stress at the contact interface, thus achieving a waterproof seal. The higher the contact stress at the interface, the better the waterproofing effect. However, due to the surface characteristics of the gasket, leakage does not occur at every point on the contact surface; seepage paths may only form at locations where there is no contact or low contact stress. Secondly, using the average contact stress across the cross-section as the design waterproofing requirement ignores the evolution of the elastic rubber gasket from contact to leakage. A deeper study of this evolution is needed. In recent years, research has proposed an elasto-plastic contact calculation method based on finite element-boundary element coupling, which determines leakage paths by constructing a microscopic contact state matrix. However, this type of method has three limitations: First, its leakage determination is based on a single contact stress threshold or binary contact state judgment, without considering physical factors such as the driving force of the pressure gradient along the seepage direction and the variability of the neighborhood stress field, resulting in the isolation and uncertainty of the identification of leakage units. Second, its leakage path identification usually adopts isotropic image segmentation algorithms (such as standard eight-connected region growth), without considering the anisotropic physical nature of seepage propagation along the hydraulic gradient direction, which easily misclassifies low-stress stripes perpendicular to the seepage direction as valid leakage paths. Third, its method focuses on the contact mechanics calculation of micro-rough surfaces and lacks a systematic leakage path search mechanism for determining the continuity from the water-facing side to the back water-facing side, making it difficult to reveal the complete evolution process of leakage from initiation to expansion and continuity. Therefore, there is an urgent need to develop a new method for identifying leakage paths at the gasket interface that integrates seepage physical mechanisms and directional path search.

[0004] Therefore, it is necessary to establish a more scientific and reliable method for searching leakage paths at the gasket interface to improve the safety of underground engineering throughout its entire life cycle. Summary of the Invention

[0005] The purpose of this invention is to provide a method for searching leakage paths at the interface of a shield tunnel sealing gasket, which can improve the safety of underground engineering throughout its entire life cycle.

[0006] This invention is achieved through the following technical solution: A method for searching leakage paths at the interface of a shield tunnel sealing gasket includes the following steps: An interfacial contact pressure matrix is ​​established based on the surface roughness of the gasket. The element in the x-th row and y-th column of the interfacial contact pressure matrix is... The interfacial contact pressure of the element representing the contact surface of the sealing gasket at coordinates (x, y) is given. , , and n are the total number of columns and rows of the sealing gasket, respectively; x represents the cell grid index along the leakage direction; and y represents the cell grid index along the vertical direction of leakage. Potential leakage units are identified by calculating the multi-factor leakage tendency index of each unit. Based on the identified potential leakage units, potential leakage areas are identified through anisotropic directional seepage tracking, resulting in a set of connected regions R, where each element in R represents a connected potential leakage area. Complete leakage paths are screened based on potential leakage areas, and the equivalent hydraulic conductivity coefficient is calculated. The leakage risk level of the complete leakage path is determined based on the equivalent hydraulic conductivity coefficient. Visualize the complete leakage path and its leakage risk level; Assess the robustness level of the complete leakage path; Obtain all sealing gaskets for a shield tunnel, as well as the maximum multifactor leakage tendency index, leakage risk level, and robustness level for each sealing gasket, and make repair decisions.

[0007] Preferably, the method for establishing the interface contact pressure matrix is ​​as follows: The contact surface of the sealing gasket is scanned using a three-dimensional optical measurement device to obtain surface height distribution data. Based on the surface height distribution data, key roughness parameters are extracted, including profile arithmetic mean deviation, profile root mean square deviation, and autocorrelation length. A three-dimensional digital roughness surface model of the contact surface of the sealing gasket is generated based on the key roughness parameters. A contact finite element model of the sealing gasket is constructed, and a three-dimensional digital rough surface model is input into the contact finite element model as the real geometric boundary condition of the contact interface. Actual assembly pressure and boundary constraints are applied to the contact finite element model, and the contact finite element model is solved by the elastoplastic contact finite element method to obtain the interface contact pressure distribution data of each element of the contact interface of the sealing gasket. The contact pressure distribution data is extracted and organized into a two-dimensional matrix form, namely the interface contact pressure matrix, according to the discrete grid positions.

[0008] Preferably, the method for calculating the multi-factor leakage tendency index is as follows: ; ; ; ; ; ; in, The multi-factor leakage tendency index is the unit with contact surface coordinates (x, y) of the sealing gasket. , , and These are the weighting coefficients. , , and These are, respectively, the base pressure deficit ratio, the stress gradient driving force along the seepage direction, the neighborhood stress field variability, and the geometric position correction coefficient for the element with contact surface coordinates (x, y) of the sealing gasket. The function to find the maximum value, Take the derivative of the interfacial contact pressure at the element (x,y) with respect to x. The length of a unit along the leakage direction. To design external water pressure, and Each of the three elements centered at the contact surface coordinates (x, y) of the sealing gasket is a unit. 3. Standard deviation and mean of interfacial contact pressure of each unit in the neighborhood. This represents the boundary effect coefficient.

[0009] Preferably, the method for identifying the potential leakage units is as follows: Set leakage tendency threshold ,like If the unit with the contact surface coordinates of the sealing gasket being (x, y) is determined to be the potential leakage unit.

[0010] Preferably, the method for identifying the potential leakage area based on anisotropic directional seepage tracing is as follows: Let the cell with coordinates (u, v) on the contact surface of the sealing gasket be the potential leakage cell, and obtain its 8-neighbor cell, let... The value range is the coordinates of the 8-neighbor unit of the unit with coordinates (u,v) on the contact surface of the sealing gasket. The cell with coordinates (u,v) on the contact surface of the sealing gasket is set as the initial seed cell, and the neighboring cells that meet the criteria are expanded into the potential leakage cells according to the improved eight-connected region growth algorithm. The neighboring units that are expanded into the potential leakage units are sequentially set as new seed units and then expanded. The termination condition for the expansion is the path bending cost between the new seed unit and the initial seed unit. Greater than the preset bending tolerance threshold: ; in, and These are the differences in y-axis and x-axis coordinates between the new seed unit and the initial seed unit, respectively. All potential leakage units are subjected to directional clustering to generate an anisotropic set of connected regions R.

[0011] Preferably, the implementation method of the improved eight-connected region growing algorithm is as follows: Calculate the orientation weights of the element with coordinates (u, v) on the contact surface of the sealing gasket and its 8 neighboring elements. First expand the directions with higher directional weights: ; in, for( The angle between the contact surface of the gasket and the x-axis. and Let be the connectivity weights along the x-axis and y-axis, respectively. ; Calculate the seepage driving force of the element with contact surface coordinates (u,v) of the sealing gasket and its 8 neighboring elements. : ; like If the driving force exceeds the preset minimum threshold, then the corresponding neighborhood will be... This extends to the potential leakage unit.

[0012] Preferably, the method for screening complete leakage paths based on potential leakage areas is as follows: If the total number of units included by any element in R is less than a preset threshold, then that element is removed to form a set of valid domains. ; In the set of effective domains In the search, elements that simultaneously contain both upstream and downstream boundary elements are defined as complete leakage paths. The upstream and downstream boundary elements represent elements with x-axis coordinates of 1 and n, respectively. The method for calculating the equivalent hydraulic conductivity coefficient of each complete leakage path is as follows: ; in, The equivalent hydraulic conductivity coefficient represents the j-th complete leakage path. Let j be the total length of the j-th complete leakage path along the x-axis. , For and These are the effective flow width of the k-th unit in the j-th complete leakage path, the multi-factor leakage tendency index, and the local equivalent gap height, respectively. The dynamic viscosity of water; according to The magnitude of the value determines the leakage risk level of the j-th complete leakage path.

[0013] Preferably, the method for evaluating the robustness level of the complete leakage path is as follows: Establish a multi-dimensional operating parameter space for the sealing gasket, including the assembly compression amount. Misalignment and twist angle And generate various sealing gasket conditions with different multi-dimensional working condition parameter spaces; The complete leakage path was selected for various sealing gasket operating conditions; Based on the number of complete leakage paths under various sealing gasket operating conditions Based on the corresponding multidimensional operating parameter space, various sensitivity indices are calculated, including the compression sensitivity index. , Sensitivity index of misalignment and torsion angle sensitivity index : ; ; ; Robustness levels are determined based on sensitivity index.

[0014] Preferably, the method for classifying the robustness level based on the sensitivity index is as follows: Set the first sensitivity index threshold. Second sensitivity index threshold , ; If the compression sensitivity index The aforementioned misalignment sensitivity index and the torsion angle sensitivity index All are not greater than If so, it is judged to have high robustness; If the compression sensitivity index The aforementioned misalignment sensitivity index and the torsion angle sensitivity index There exists at least one greater than and less than And none of them are greater than If so, it is judged to have moderate robustness; If the compression sensitivity index The aforementioned misalignment sensitivity index and the torsion angle sensitivity index There exists at least one greater than If it is, then it is judged as having low robustness.

[0015] Preferably, the method for obtaining the repair decision is as follows: Arrange all the gaskets in descending order of leakage risk level, and use this order as the repair priority. If multiple sealing gaskets have the same leakage risk level, the repair urgency of each complete leakage path is calculated, and repairs are carried out in descending order of repair urgency.

[0016] Preferably, the method for calculating the urgency of repair is as follows:

[0017] in, Representing the The equivalent hydraulic conductivity coefficient of the j-th complete leakage path of a sealing gasket. To represent the first The maximum equivalent hydraulic conductivity coefficient of all complete leakage paths of a gasket. For the first The total length of the j-th complete leakage path of a sealing gasket along the x-axis. For the first The maximum value of the multi-factor leakage tendency index of all units in the j-th complete leakage path of the sealing gasket. The threshold value is the preset threshold value for the multi-factor leakage tendency index.

[0018] The technical solution of the present invention has at least the following advantages and beneficial effects: This invention overcomes the isolation defects and lack of physical mechanism of the single contact stress threshold judgment in the prior art by constructing a multi-factor leakage tendency index. It improves the leakage criterion from static numerical comparison to a comprehensive dynamic evaluation that integrates the seepage physical driving mechanism and local field effect, which significantly improves the scientificity and accuracy of leakage risk identification. This invention identifies potential leakage areas based on anisotropic directional seepage tracing, overcoming the fundamental defect that the isotropic assumption of the standard eight-connected region growth algorithm does not match the actual physical reality of seepage. It achieves directional tracing of leakage paths that is more in line with the physical nature, effectively eliminates the problem of false connection of low-stress stripes perpendicular to the seepage direction, and reveals the evolution process of leakage paths from initiation to expansion and connection, which has stronger physical credibility and engineering guidance value. Based on the continuous characteristics of the leakage tendency index and the directional identification results of anisotropic connected regions, this invention establishes a multi-level state discrimination criterion. It can be applied to the numerical simulation results analysis under different compression and misalignment conditions in the design stage, and can also be combined with the interface pressure real-time monitoring system to be developed in the future for online assessment of the waterproof status of tunnel joints during operation, leakage risk evolution prediction and preventive maintenance decision support. This invention is rationally designed and adapted to the real-time data-driven mode of digital twin systems. It can serve as the core technology for the waterproof performance evaluation module in a tunnel digital twin, enabling dynamic synchronization of the physical tunnel and the virtual model in terms of waterproof status, leakage risk prediction, and intelligent maintenance decision-making. Attached Figure Description

[0019] Figure 1 This is a flowchart illustrating the method for searching leakage paths at the interface of a shield tunnel sealing gasket provided in Embodiment 1 of the present invention. Figure 2 This is a schematic diagram of a case of non-uniform contact pressure distribution provided in Embodiment 1 of the present invention; Figure 3 for Figure 2 A schematic diagram illustrating the distribution of the multifactor leakage tendency index in the case study; Figure 4 for Figure 2 A schematic diagram of the results of anisotropic directional seepage tracing in the case study; Figure 5 for Figure 2 A schematic diagram showing the equivalent hydraulic conductivity results for the case. Figure 6 for Figure 2 A comprehensive and visual presentation of case studies; Figure 7 This is a schematic diagram of the repair priority order provided in Embodiment 1 of the present invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0021] Example This embodiment provides a method for searching the leakage path at the interface of a shield tunnel sealing gasket. (See reference...) Figure 1 This includes the following steps: Step S1: Establish the interface contact pressure matrix based on the surface roughness of the sealing gasket.

[0022] Existing methods for obtaining the interfacial contact pressure of gaskets typically simplify the sealing interface to an ideal smooth plane, obtaining a uniform two-dimensional contact stress distribution through macroscopic finite element analysis. This assumption differs fundamentally from engineering reality: the actual surface of an elastic rubber gasket has a microscopically rough morphology, and the actual contact state of the rough peaks results in highly non-uniform contact pressure at the microscopic scale. Water does not permeate in the macroscopically average low-stress zone, but rather leaks along the microscopic gap channels between the rough peaks. Therefore, this embodiment directly incorporates the gasket surface roughness into the construction process of the contact pressure matrix, establishing a method for obtaining the contact pressure matrix that considers surface roughness. Specifically, the method is as follows: Step S101: The contact surface of the sealing gasket is scanned using a three-dimensional optical measurement device to obtain surface height distribution data. Based on the surface height distribution data, key roughness parameters are extracted, including profile arithmetic mean deviation, profile root mean square deviation, and autocorrelation length. A three-dimensional digital roughness surface model of the contact surface of the sealing gasket is generated based on the key roughness parameters.

[0023] Step S102: Construct a contact finite element model of the sealing gasket, and input the three-dimensional digital rough surface model as the real geometric boundary condition of the contact interface (replacing the ideal smooth plane assumption in the traditional method) into the contact finite element model. Apply actual assembly pressure and boundary constraints to the contact finite element model, and solve the contact finite element model using the elastoplastic contact finite element method to obtain the interface contact pressure distribution data of each element of the contact interface of the sealing gasket. The contact state (complete contact, partial contact, or no contact) between the roughness peaks of the sealing gasket can be directly reflected in the finite element solution, thus obtaining the non-uniform contact pressure distribution result that reflects the influence of the real rough surface. The essential difference between this step and the traditional method is that surface roughness is elevated from a "neglected secondary factor" to a "core geometric input that determines the contact state".

[0024] Step S103: Extract and organize the contact pressure distribution data into a two-dimensional interface contact pressure matrix according to the discrete grid positions. Each element in the interface contact pressure matrix directly reflects the actual contact state of the corresponding rough peak, rather than the averaged result under the traditional smooth plane assumption.

[0025] The interface contact pressure matrix in this embodiment is as follows: .

[0026] Its x-th row and y-th column element The interfacial contact pressure of the element representing the contact surface of the sealing gasket at coordinates (x, y) is given. , , Let and n be the total number of columns and rows of the sealing gasket, respectively. Let x represent the cell grid index along the leakage direction (from the water-facing side to the back-facing side), and y represent the cell grid index along the vertical direction of leakage. The number of rows n and columns m of matrix A are determined by the cell grid density.

[0027] A result of a non-uniform contact pressure distribution obtained according to the method in step S1 can be found here. Figure 2 , Figure 2 The horizontal axis represents the length of the gasket, which is also the leakage direction in this case, and the vertical axis represents the width of the gasket, which is perpendicular to the leakage direction. Different colors represent different contact pressures (MPa).

[0028] Step S2: Identify potential leakage units by calculating the multi-factor leakage tendency index of each unit.

[0029] As a preferred embodiment, the method for calculating the multi-factor leakage tendency index is as follows: ; ; ; ; ; ; in, The multi-factor leakage tendency index is the unit with contact surface coordinates (x, y) of the sealing gasket. , , and These are the weighting coefficients. , , and These are, respectively, the base pressure deficit ratio, the stress gradient driving force along the seepage direction, the neighborhood stress field variability, and the geometric position correction coefficient for the element with contact surface coordinates (x, y) of the sealing gasket. The function to find the maximum value, Take the derivative of the interfacial contact pressure at the element (x,y) with respect to x. The length of a unit along the leakage direction. To design external water pressure, and Each of the three elements centered at the contact surface coordinates (x, y) of the sealing gasket is a unit. 3. Standard deviation and mean of interfacial contact pressure of each unit in the neighborhood. This represents the boundary effect coefficient.

[0030] In the above scheme, the base pressure deficit ratio reflects the degree of insufficiency of the unit's interfacial contact pressure relative to the design external water pressure P. The stress gradient driving force along the seepage direction characterizes the physical driving force of water seeping from the upstream side to the downstream side, and is positive only when a pressure drop gradient exists along the seepage direction. The neighborhood stress field variability reflects the dispersion and instability of the local stress field. The geometric position correction factor is responsible for considering the differences in leakage sensitivity caused by stress concentration or relaxation in the gasket edge area.

[0031] Based on this, the method for identifying the potential leakage units is as follows: Set leakage tendency threshold ,like If the unit with the contact surface coordinates of the sealing gasket being (x, y) is determined to be the potential leakage unit.

[0032] All potential leakage units constitute set L. This multi-factor evaluation method overcomes the isolation limitation of single threshold judgment, elevating the leakage criterion from static stress comparison to a comprehensive evaluation integrating physical driving mechanisms and local field effects. Based on Figure 2 The distribution of the multifactor leakage tendency index obtained from the case can be found in [reference needed]. Figure 3 .

[0033] Step S3: Based on the identified potential leakage units, identify potential leakage areas using anisotropic directional seepage tracking to obtain a set of connected regions R, where each element in R represents a connected potential leakage area.

[0034] Traditional eight-connected region growing algorithms are isotropic image segmentation methods. Directly applying them to seepage path identification has significant physical limitations: in actual seepage processes, water flows along the hydraulic gradient direction (from the upstream side to the downstream side), and low-stress "stripes" perpendicular to the flow direction will not form effective seepage channels. Therefore, this embodiment proposes an anisotropic directional seepage tracking algorithm, which achieves connected region identification that better reflects the physical nature of seepage through a triple mechanism of direction weight constraints, seepage driving force criteria, and path bending cost.

[0035] In this embodiment, the method for identifying the potential leakage area based on anisotropic directional seepage tracking is as follows: Let the cell with coordinates (u, v) on the contact surface of the sealing gasket be the potential leakage cell, and obtain its 8-neighbor cell, let... The value range is the coordinates of the 8-neighbor unit of the unit with coordinates (u,v) on the contact surface of the sealing gasket. The cell with coordinates (u,v) on the contact surface of the sealing gasket is set as the initial seed cell, and the neighboring cells that meet the criteria are expanded into the potential leakage cells according to the improved eight-connected region growth algorithm. The neighboring units that are expanded into the potential leakage units are sequentially set as new seed units and then expanded. The termination condition for the improved 8-connected region growing algorithm is the path bending cost between the new seed unit and the initial seed unit. Greater than the preset bending tolerance threshold: ; in, and These are the differences in y-axis and x-axis coordinates between the new seed unit and the initial seed unit, respectively. This mechanism effectively eliminates the possibility of low-stress stripes perpendicular to the main seepage direction being incorrectly connected, ensuring that the identified leakage channels are physically accessible. The bending tolerance threshold is typically set between 0.3 and 0.5.

[0036] All potential leakage units are subjected to directional clustering to generate an anisotropic set of connected regions R.

[0037] In this embodiment, the improved 8-connected region growing algorithm is implemented as follows: Calculate the orientation weights of the element with coordinates (u, v) on the contact surface of the sealing gasket and its 8 neighboring elements. First expand the directions with higher directional weights: ; in, for( The angle between the contact surface of the gasket and the x-axis. and Let be the connectivity weights along the x-axis and y-axis, respectively. In this embodiment, the preferred value is... , ; Calculate the seepage driving force of the element with contact surface coordinates (u,v) of the sealing gasket and its 8 neighboring elements. : ; like If the driving force exceeds the preset minimum threshold, then the corresponding neighborhood will be... This extends to the potential leakage unit. This criterion ensures that the seepage path extends along the direction of pressure reduction, avoiding reverse false connections caused by local stress fluctuations and preventing false expansion caused by numerical noise.

[0038] Figure 4 for Figure 2 A schematic diagram of the results of anisotropic directional seepage tracing in the case.

[0039] Step S4: Screen complete leakage paths based on potential leakage areas, calculate the equivalent hydraulic conductivity coefficient, and determine the leakage risk level of the complete leakage path based on the equivalent hydraulic conductivity coefficient.

[0040] The method for screening complete leakage paths based on potential leakage areas is as follows: Step S401: If the total number of units included by any element in R is less than a preset threshold (e.g., set to 2), then remove that element to form a set of valid domains. .

[0041] Step S402: In the set of valid domains In the search, elements that simultaneously contain both upstream and downstream boundary elements are defined as complete leakage paths. The upstream and downstream boundary elements represent elements with x-axis coordinates of 1 and n, respectively. As long as such an area exists, it is determined that a complete, penetrating leakage path has been formed, and the sealing gasket is in a "leaking" state.

[0042] Step S403: The method for calculating the equivalent hydraulic conductivity coefficient of each complete leakage path based on the leakage tendency index and local geometric features of each unit along the path is as follows: ; in, The equivalent hydraulic conductivity coefficient represents the j-th complete leakage path. Let j be the total length of the j-th complete leakage path along the x-axis. , For and These are the effective flow width of the k-th unit in the j-th complete leakage path, the multi-factor leakage tendency index, and the local equivalent gap height (average gap distance in the non-contact area), respectively. This is the dynamic viscosity of water.

[0043] Step S404: According to The magnitude of the value determines the leakage risk level of the j-th complete leakage path.

[0044] This embodiment draws on the parallel plate gap flow theory, combining the flow capacity of micro-gap with the macro-level multi-factor leakage tendency index, achieving a technological leap from qualitative "whether there is leakage" to quantitative "how much leakage." Based on The value can be obtained through two thresholds. and Leakage risk is classified into three levels: Low-risk leakage channels: There is trace seepage, but it is within an acceptable range and requires regular monitoring. Medium-risk leakage channels: The leakage flow has affected the waterproofing effect, and reinforcement measures are recommended. High-risk leakage channels: The leakage flow rate seriously threatens waterproofing safety and requires immediate attention. Threshold and Determined based on the waterproofing grade and allowable leakage standards of the project.

[0045] Figure 5 for Figure 2 A schematic diagram showing the equivalent hydraulic conductivity coefficient of the case.

[0046] In addition, after obtaining all complete leakage paths, the path with the largest span in the x-axis direction can be selected as the most unfavorable leakage path, which is the weakest link in waterproofing.

[0047] Step S5: Visualize the complete leakage path and its leakage risk level (refer to...). Figures 2-5 ).exist Figures 2-5 Based on this, comprehensive visualization can also be provided. (See attached image) Figure 6 .

[0048] Step S6: Assess the robustness level of the complete leakage path.

[0049] In practical engineering, the waterproof performance of gaskets is simultaneously affected by a combination of factors, including assembly compression, joint misalignment, and assembly torsion angle. Existing methods typically analyze only a single condition and cannot assess the waterproof robustness of gaskets under complex combinations of conditions. Therefore, in this embodiment, the method for evaluating the robustness level of the complete leakage path is as follows: Establish a multi-dimensional operating parameter space for the sealing gasket, including the assembly compression amount. Misalignment and twist angle And generate various sealing gasket conditions with different multi-dimensional working condition parameter spaces; The complete leakage path was selected for various sealing gasket operating conditions; Based on the number of complete leakage paths under various sealing gasket operating conditions Based on the corresponding multidimensional operating parameter space, various sensitivity indices are calculated, including the compression sensitivity index. , Sensitivity index of misalignment and torsion angle sensitivity index : ; ; ; Robustness levels are determined based on sensitivity index.

[0050] The method for classifying the robustness level based on the sensitivity index is as follows: Set the first sensitivity index threshold. Second sensitivity index threshold , ; If the compression sensitivity index The aforementioned misalignment sensitivity index and the torsion angle sensitivity index All are not greater than If the result is positive, it is judged to be of high robustness, which means that the sealing gasket has good waterproof reliability under this combination of working conditions. If the compression sensitivity index The aforementioned misalignment sensitivity index and the torsion angle sensitivity index There exists at least one greater than and less than And none of them are greater than If the robustness is moderate, it means that the waterproof performance of the sealing gasket is somewhat sensitive to changes in working conditions, and a safety margin needs to be reserved in the design. If the compression sensitivity index The aforementioned misalignment sensitivity index and the torsion angle sensitivity index There exists at least one greater than If the condition is not met, it is judged as having low robustness, meaning that the waterproof performance of the gasket is highly sensitive to changes in operating conditions, and its use is not recommended under this combination of operating conditions.

[0051] It should be noted that for Level 1 waterproofing projects (where water seepage is not allowed), it is recommended to use... It is 0.5. The value is 2.0; for Class II waterproofing projects (where minor seepage is permissible), a value of 2.0 can be used. It is 1.5. It is 4.0.

[0052] Step S7: Obtain all sealing gaskets for a shield tunnel, as well as the maximum multi-factor leakage tendency index, leakage risk level, and robustness level for each sealing gasket, and obtain a repair decision.

[0053] In practical engineering applications, a shield tunnel contains dozens to hundreds of segment joints, and each joint's sealing gasket interface may have its own leakage risk. Therefore, the identification results must be translated into actionable operation and maintenance decisions oriented towards multiple sealing gaskets to realize practical value. It should be particularly noted that for shield tunnel segment joints that have already been constructed, the geometry of the sealing gaskets is fixed, and it is impossible to achieve waterproofing enhancement by changing the flange height or cross-sectional shape.

[0054] The method for obtaining the repair decision in this embodiment is as follows: A comprehensive leakage risk matrix can be constructed. , The shield tunnels are respectively the first The matrix, which includes the gasket identification, equivalent hydraulic conductivity, and maximum multi-factor leakage tendency index of each gasket, integrates the scattered joint-level assessment results into a global risk view at the tunnel section level. This allows maintenance personnel to clearly understand the leakage risk distribution of gaskets throughout the entire line, overcoming the limitations of traditional single-point assessments that cannot grasp the overall situation.

[0055] All the sealing gaskets can be arranged from highest to lowest leakage risk level, and this order can be used as the repair priority. During repairs, special inspections and emergency treatments can be arranged for high-risk leakage channels, and if necessary, a water-stop curtain or local secondary lining reinforcement can be activated; medium-risk leakage channels can be included in the regular monitoring plan and re-evaluated quarterly; and routine inspections can be performed on medium-risk leakage channels. This tiered treatment strategy prioritizes the allocation of limited maintenance resources to high-risk areas, realizing a shift from a "comprehensive survey" to a "precisely targeted" maintenance model. A diagram illustrating the repair priority order can be found here. Figure 7 .

[0056] When multiple segment joints simultaneously present medium- to high-risk conditions, it is necessary to determine the order of treatment to achieve a reasonable allocation of operation and maintenance resources. That is, if multiple sealing gaskets have the same leakage risk level, the urgency of repairing each complete leakage path is calculated separately, and repairs are carried out in descending order of urgency to ensure that high-risk joints are treated first.

[0057] As a preferred embodiment, the method for calculating the urgency of the repair is as follows: ; in, Representing the The equivalent hydraulic conductivity coefficient of the j-th complete leakage path of a sealing gasket. To represent the first The maximum equivalent hydraulic conductivity coefficient of all complete leakage paths of a gasket. For the first The total length of the j-th complete leakage path of a sealing gasket along the x-axis. For the first The maximum value of the multi-factor leakage tendency index of all units in the j-th complete leakage path of the sealing gasket. The threshold value is the preset threshold value for the multi-factor leakage tendency index.

[0058] The first term in the above expression reflects the severity of the leakage flux, the second term reflects the path connectivity, and the third term reflects the local leakage peak. This priority ranking mechanism ensures that the most severe leakage channels are addressed first, avoiding blind repairs based on traditional experience-based judgments.

[0059] This embodiment addresses the isolated shortcomings of existing technologies in judging single contact stress thresholds and the discrepancy between the isotropic assumption of the standard eight-connected region growing algorithm and the actual physical reality of seepage. It achieves a technological upgrade by constructing a multi-factor leakage tendency index (LPI) that integrates pressure deficit, stress gradient driving force, neighborhood variability, and geometric position effects, moving from static stress comparison to a comprehensive evaluation of physical driving mechanisms. Furthermore, it innovates the method of moving from isotropic image segmentation to anisotropic physical seepage simulation through a directional seepage tracking algorithm with triple constraints of anisotropic direction weights, seepage driving force criteria, and path bending cost. This method can automatically and quantitatively identify leakage risk areas at the gasket contact interface, accurately track leakage paths connecting the upstream and downstream sides, and scientifically assess the sealing status and provide critical early warnings. It can provide core technical support for shield tunnel waterproofing design, health monitoring, and digital twins.

[0060] The above are merely preferred embodiments of the present invention and are not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for searching leakage paths at the interface of a shield tunnel sealing gasket, characterized in that, Includes the following steps: An interfacial contact pressure matrix is ​​established based on the surface roughness of the gasket. The element in the x-th row and y-th column of the interfacial contact pressure matrix is... The interfacial contact pressure of the element representing the contact surface of the sealing gasket at coordinates (x, y) is given. , , and n are the total number of columns and rows of the sealing gasket, respectively; x represents the cell grid index along the leakage direction; and y represents the cell grid index along the vertical direction of leakage. Potential leakage units are identified by calculating the multi-factor leakage tendency index of each unit. Based on the identified potential leakage units, potential leakage areas are identified through anisotropic directional seepage tracking, resulting in a set of connected regions R, where each element in R represents a connected potential leakage area. Complete leakage paths are screened based on potential leakage areas, and the equivalent hydraulic conductivity coefficient is calculated. The leakage risk level of the complete leakage path is determined based on the equivalent hydraulic conductivity coefficient. Visualize the complete leakage path and its leakage risk level; Assess the robustness level of the complete leakage path; Obtain all sealing gaskets for a shield tunnel, as well as the maximum multifactor leakage tendency index, leakage risk level, and robustness level for each sealing gasket, and make repair decisions.

2. The method for searching leakage paths at the interface of a shield tunnel sealing gasket according to claim 1, characterized in that, The method for establishing the interface contact pressure matrix is ​​as follows: The contact surface of the sealing gasket is scanned using a three-dimensional optical measurement device to obtain surface height distribution data. Based on the surface height distribution data, key roughness parameters are extracted, including profile arithmetic mean deviation, profile root mean square deviation, and autocorrelation length. A three-dimensional digital roughness surface model of the contact surface of the sealing gasket is generated based on the key roughness parameters. A contact finite element model of the sealing gasket is constructed, and a three-dimensional digital rough surface model is input into the contact finite element model as the real geometric boundary condition of the contact interface. Actual assembly pressure and boundary constraints are applied to the contact finite element model, and the contact finite element model is solved by the elastoplastic contact finite element method to obtain the interface contact pressure distribution data of each element of the contact interface of the sealing gasket. The contact pressure distribution data is extracted and organized into a two-dimensional matrix form, namely the interface contact pressure matrix, according to the discrete grid positions.

3. The method for searching leakage paths at the interface of a shield tunnel sealing gasket according to claim 1, characterized in that, The method for calculating the multi-factor leakage tendency index is as follows: ； ； ； ； ； ； in, The multi-factor leakage tendency index is the unit with contact surface coordinates (x, y) of the sealing gasket. , , and These are the weighting coefficients. , , and These are, respectively, the base pressure deficit ratio, the stress gradient driving force along the seepage direction, the neighborhood stress field variability, and the geometric position correction coefficient for the element with contact surface coordinates (x, y) of the sealing gasket. The function to find the maximum value, Take the derivative of the interfacial contact pressure at the element (x,y) with respect to x. The length of a unit along the leakage direction. To design external water pressure, and Each of the three elements centered at the contact surface coordinates (x, y) of the sealing gasket is a unit.

3. Standard deviation and mean of interfacial contact pressure of each unit in the neighborhood. This is the boundary effect coefficient; Set leakage tendency threshold ,like If the unit with the contact surface coordinates of the sealing gasket being (x, y) is determined to be the potential leakage unit.

4. The method for searching the leakage path at the interface of a shield tunnel sealing gasket according to claim 1, characterized in that, The method for identifying potential leakage areas based on anisotropic directional seepage tracing is as follows: Let the cell with coordinates (u, v) on the contact surface of the sealing gasket be the potential leakage cell, and obtain its 8-neighbor cell, let... The value range is the coordinates of the 8-neighbor unit of the unit with coordinates (u,v) on the contact surface of the sealing gasket. The cell with coordinates (u,v) on the contact surface of the sealing gasket is set as the initial seed cell, and the neighboring cells that meet the criteria are expanded into the potential leakage cells according to the improved eight-connected region growth algorithm. The neighboring units that are expanded into the potential leakage units are sequentially set as new seed units and then expanded. The termination condition for the expansion is the path bending cost between the new seed unit and the initial seed unit. Greater than the preset bending tolerance threshold: ； in, and These are the differences in y-axis and x-axis coordinates between the new seed unit and the initial seed unit, respectively. All potential leakage units are subjected to directional clustering to generate an anisotropic set of connected regions R.

5. The method for searching leakage paths at the interface of a shield tunnel sealing gasket according to claim 4, characterized in that, The implementation method of the improved 8-connected region growing algorithm is as follows: Calculate the orientation weights of the element with coordinates (u, v) on the contact surface of the sealing gasket and its 8 neighboring elements. First expand the directions with higher directional weights: ； in, for( The angle between the contact surface of the gasket and the x-axis. and Let be the connectivity weights along the x-axis and y-axis, respectively. ; Calculate the seepage driving force of the element with contact surface coordinates (u,v) of the sealing gasket and its 8 neighboring elements. : ; like If the driving force exceeds the preset minimum threshold, then the corresponding neighborhood will be... This extends to the potential leakage unit.

6. The method for searching leakage paths at the interface of a shield tunnel sealing gasket according to claim 1, characterized in that, The method for screening complete leakage paths based on potential leakage areas is as follows: If the total number of units included by any element in R is less than a preset threshold, then that element is removed to form a set of valid domains. ; In the set of effective domains In the search, elements that simultaneously contain both upstream and downstream boundary elements are defined as complete leakage paths. The upstream and downstream boundary elements represent elements with x-axis coordinates of 1 and n, respectively. The method for calculating the equivalent hydraulic conductivity coefficient of each complete leakage path is as follows: ； in, The equivalent hydraulic conductivity coefficient represents the j-th complete leakage path. Let j be the total length of the j-th complete leakage path along the x-axis. , For and These are the effective flow width of the k-th unit in the j-th complete leakage path, the multi-factor leakage tendency index, and the local equivalent gap height, respectively. The dynamic viscosity of water; according to The magnitude of the value determines the leakage risk level of the j-th complete leakage path.

7. The method for searching leakage paths at the interface of a shield tunnel sealing gasket according to claim 1, characterized in that, The method for evaluating the robustness level of the complete leakage path is as follows: Establish a multi-dimensional operating parameter space for the sealing gasket, including the assembly compression amount. Misalignment and twist angle And generate various sealing gasket conditions with different multi-dimensional working condition parameter spaces; The complete leakage path was selected for various sealing gasket operating conditions; Based on the number of complete leakage paths under various sealing gasket operating conditions Based on the corresponding multidimensional operating parameter space, various sensitivity indices are calculated, including the compression sensitivity index. , Sensitivity index of misalignment and torsion angle sensitivity index : ； ； ； Robustness levels are determined based on sensitivity index.

8. The method for searching leakage paths at the interface of a shield tunnel sealing gasket according to claim 7, characterized in that, The method for classifying the robustness level based on the sensitivity index is as follows: Set the first sensitivity index threshold. Second sensitivity index threshold , ; If the compression sensitivity index The aforementioned misalignment sensitivity index and the torsion angle sensitivity index All are not greater than If so, it is judged to have high robustness; If the compression sensitivity index The aforementioned misalignment sensitivity index and the torsion angle sensitivity index There exists at least one greater than and less than And none of them are greater than If so, it is judged to have moderate robustness; If the compression sensitivity index The aforementioned misalignment sensitivity index and the torsion angle sensitivity index There exists at least one greater than If it is, then it is judged as having low robustness.

9. The method for searching leakage paths at the interface of a shield tunnel sealing gasket according to claim 1, characterized in that, The method for obtaining the repair decision is as follows: Arrange all the gaskets in descending order of leakage risk level, and use this order as the repair priority. If multiple sealing gaskets have the same leakage risk level, the repair urgency of each complete leakage path is calculated, and repairs are carried out in descending order of repair urgency.

10. The method for searching leakage paths at the interface of a shield tunnel sealing gasket according to claim 9, characterized in that, The method for calculating the urgency of the repair is as follows: in, Representing the The equivalent hydraulic conductivity coefficient of the j-th complete leakage path of a sealing gasket. To represent the first The maximum equivalent hydraulic conductivity coefficient of all complete leakage paths of a gasket. For the first The total length of the j-th complete leakage path of a sealing gasket along the x-axis. For the first The maximum value of the multi-factor leakage tendency index of all units in the j-th complete leakage path of the sealing gasket. The threshold value is the preset threshold value for the multi-factor leakage tendency index.

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