Tunnel leakage identification method based on optical fiber sensing

Abstract

The invention relates to the technical field of tunnel leakage identification, in particular to a tunnel leakage identification method based on optical fiber sensing, and the method comprises the steps: obtaining temperature data collected by an optical fiber sensing network disposed along the wall surface of a tunnel; identifying a temperature abnormal point based on the temperature data; determining a potential leakage point according to the position of the temperature abnormal point and the temperature change characteristic; according to the method, firstly, optical fiber sensing networks are arranged in the axial direction and the circumferential direction of the wall face of the tunnel, so that the surface of the whole tunnel is completely covered, and the problem that hidden leakage is difficult to find through a traditional method is solved; and secondly, the method combines active and passive temperature field leakage detection technologies, and the accuracy and reliability of leakage identification are greatly improved. The active heating technology can enhance temperature comparison between a leakage point and a surrounding area, the passive monitoring can realize long-term and continuous leakage monitoring, and the two technologies supplement each other to form a comprehensive monitoring system.

Description

Technical Field

[0001] The invention relates to the technical field of tunnel leakage identification, in particular to a tunnel leakage identification method based on optical fiber sensing. Background Art

[0002] With the acceleration of urbanization and the extensive use of underground space, tunnel engineering plays an increasingly important role in modern infrastructure construction. However, tunnel leakage has always been a major problem that has troubled the engineering community, not only affecting the normal use of tunnels, but also causing serious safety hazards and economic losses.

[0003] Traditional tunnel leakage detection methods mainly rely on manual inspections and regular checks. Although this method is intuitive, it has problems such as low efficiency, strong subjectivity, and difficulty in timely detection of hidden leakage. With the development of technology, some new detection methods have gradually been applied in practice, such as infrared thermal imaging and geological radar. These methods have improved the efficiency and accuracy of detection to a certain extent, but there are still many limitations. For example, infrared thermal imaging is greatly affected by ambient temperature and it is difficult to carry out long-term continuous monitoring; although geological radar can detect the internal conditions of tunnel structures, the equipment is expensive, the operation is complicated, and it is difficult to achieve real-time monitoring.

[0004] In recent years, fiber optic sensing technology has received widespread attention in the field of structural health monitoring due to its advantages such as high sensitivity, resistance to electromagnetic interference, and distributed measurement. However, the application of fiber optic sensing technology to tunnel leakage detection still faces many challenges. First, the tunnel environment is complex, and how to effectively deploy a fiber optic sensing network to achieve comprehensive coverage is a difficult problem. Secondly, the temperature distribution in the tunnel is affected by many factors, and how to accurately identify temperature anomalies caused by leakage is also a key issue. In addition, existing fiber optic sensing methods often lack quantitative assessment of the degree of leakage, making it difficult to provide strong support for tunnel maintenance decisions.

[0005] The principle of distributed optical fiber detection of tunnel leakage is that when water leakage occurs, the temperature of this section of the tunnel will be lower than the surrounding temperature, and the use of distributed optical fiber can detect the temperature change, thereby determining the presence and location of water leakage. At present, due to the late start of distributed optical fiber temperature measurement technology in China, most equipment needs to be imported and is expensive, and distributed optical fiber is not widely used in China. At present, distributed optical fiber is mainly used for leakage detection of water pipelines and dams and fire monitoring in tunnels.

[0006] Li Zhen, Jiang Mengmeng, Yin Qiuyu, etc. [1][2] have conducted research on tunnel fire monitoring systems based on distributed optical fiber sensing technology, and used physical model tests, dynamic simulation, numerical simulation analysis and other methods to verify the feasibility and accuracy of distributed optical fiber in monitoring tunnel fires; Zeng Tiemei et al. [3]In the study of distributed optical fiber monitoring of tunnel fires, it was mentioned that it can be used to detect tunnel leakage, but no further research was conducted; Wang et al. [4] Distributed optical fiber was used to detect leakage in water pipes. The test showed that the distributed optical fiber temperature measurement system has good detection performance for water pipes of different materials; Xu Xiangyu [5] Distributed optical fiber technology is used to monitor the leakage of dams, and the accuracy is verified by numerical analysis and fitting. It can be seen that distributed optical fiber is mostly used for monitoring and early warning of tunnel fires, and there is relatively little research on its use in tunnel leakage detection.

[0007] [1] Jiang Mengmeng. Research on several influencing factors of the application of distributed optical fiber temperature sensing fire detection system in highway tunnels[D]. University of Science and Technology of China, 2014.

[0008] [2] YIN Qiuyu. Research on temperature distribution characteristics of tunnel fire based on distributed optical fiber monitoring[D]. Hubei University of Technology, 2021.

[0009] [3] Zeng Tiemei, Xu Weijun, Hou Jianguo. Application of distributed optical fiber temperature measurement technology in tunnel fire and leakage detection [J]. Journal of Disaster Prevention and Mitigation Engineering, 2007(01):52-56.

[0010] [4]Wang Qiang, Gu Xiaohong, Zhang Zhiwang, Long Zhihong, Zhao Ya. On-LineLeakage Detection in Buried Tap Water Distribution Pipes Using DistributedTemperature Sensing[J]. Journal of Pipeline Systems Engineering and Practice, 2022, 13(2).

[0011] [5]Xu Xiangyu. Research on leakage monitoring method based on distributed optical fiber temperature sensing technology[D]. Hubei University of Technology, 2012.

[0012] In view of the above problems, a new method is urgently needed to achieve comprehensive, accurate and real-time monitoring of tunnel leakage. This method should be able to overcome the limitations of existing technologies and provide more reliable and comprehensive tunnel leakage information, thereby providing strong technical support for the safe operation and maintenance of tunnels. Summary of the invention

[0013] The present invention aims at the deficiencies of the prior art and proposes a tunnel leakage identification method based on optical fiber sensing. The method realizes high-precision and real-time monitoring of tunnel leakage through innovative optical fiber layout scheme, temperature data processing algorithm and leakage assessment model.

[0014] The present invention proposes a tunnel leakage identification method based on optical fiber sensing, comprising:

[0015] The acquisition steps include:

[0016] Obtain temperature data collected by a fiber-optic sensor network arranged along the tunnel wall;

[0017] The processing steps include:

[0018] Based on the temperature data, identifying temperature abnormal points;

[0019] Determine potential leakage points according to the location of the temperature anomaly point and the temperature change characteristics;

[0020] The output steps include:

[0021] Generate a leakage identification result including the location information of the potential leakage point.

[0022] Preferably, the obtaining step specifically comprises:

[0023] Longitudinal armored optical fibers are laid axially and circumferentially along the tunnel wall;

[0024] The optical fiber is laid in a circular manner at the tunnel joints;

[0025] Temperature data is collected through the longitudinal armored optical fiber and the circumferential optical fiber.

[0026] As a preference, it also includes:

[0027] The longitudinal armored optical fiber and the circumferential optical fiber are fixed tightly to the tunnel wall using a clamp.

[0028] Preferably, the processing step further comprises:

[0029] Obtain tunnel ambient temperature data;

[0030] Based on the tunnel environment temperature data, temperature correction is performed on the temperature data.

[0031] Preferably, the processing step further comprises:

[0032] Active temperature field leak detection method is used, including:

[0033] Change the temperature distribution of the tunnel wall through artificial heating system;

[0034] Collect temperature data after heating;

[0035] Based on the temperature data after heating, temperature abnormality points are identified.

[0036] Preferably, the artificial heating system comprises:

[0037] Heating pipes are laid along the tunnel walls;

[0038] A circulating hot water device connected to the heating pipe.

[0039] Preferably, the processing step further comprises:

[0040] Passive temperature field leak detection method is used, including:

[0041] Use self-heating armored temperature measuring optical cable as temperature sensor;

[0042] Collect temperature data during tunnel pit dewatering;

[0043] Based on the temperature data, temperature anomalies caused by water flow are identified.

[0044] Preferably, the processing step further comprises:

[0045] Determine the leakage range based on the spatial distribution characteristics of the temperature anomaly points;

[0046] Evaluate the degree of leakage based on the size of the leakage range.

[0047] Preferably, the processing step further comprises:

[0048] Based on historical temperature data, a normal temperature distribution model of the tunnel is established;

[0049] The current temperature data is compared with the normal temperature distribution model to identify abnormal temperature changes.

[0050] Preferably, the output step further comprises:

[0051] Generate a visual leakage map including the location, scope and extent of leakage;

[0052] When a serious leak is detected, an alarm signal is triggered.

[0053] The beneficial effects of the present invention are mainly reflected in the following aspects:

[0054] The method of the present invention has many significant advantages and beneficial effects. First, by laying out the optical fiber sensing network axially and circumferentially along the tunnel wall, comprehensive coverage of the entire tunnel surface is achieved, overcoming the problem that traditional methods are difficult to detect hidden leaks. Secondly, this method combines active and passive temperature field leak detection technologies, greatly improving the accuracy and reliability of leak identification. Active heating technology can enhance the temperature contrast between the leak point and the surrounding area, while passive monitoring can achieve long-term and continuous leakage monitoring. The two technologies complement each other to form a comprehensive monitoring system.

[0055] In addition, the present invention introduces a normal temperature distribution model based on historical data, which effectively reduces false alarms caused by environmental factors and improves the accuracy of leakage identification. By analyzing the spatial distribution characteristics of temperature anomalies, this method can not only determine the leakage location, but also evaluate the scope and degree of leakage, providing more comprehensive information support for tunnel maintenance decisions.

[0056] Finally, the visual leakage map and multi-level alarm mechanism of the present invention make the monitoring results more intuitive and easy to understand, which helps managers to quickly understand the tunnel conditions and make timely responses. This not only improves the efficiency of tunnel maintenance, but also greatly reduces the risk of safety accidents caused by leakage problems.

[0057] The present invention adopts optical fiber sensing technology, using optical fiber to transmit and detect light of a specific wavelength, and can achieve real-time, online, and continuous monitoring of the object being measured. The optical fiber sensor has high precision and high sensitivity, and can accurately capture the tiny temperature changes caused by leakage, thereby improving the accuracy of leakage monitoring.

[0058] Whether it is active temperature field leak detection or passive temperature field leak detection, the present invention uses the change of temperature field to monitor leakage. Since temperature is a relatively stable physical quantity and is less susceptible to external interference, this method can provide more reliable monitoring results.

[0059] The present invention can realize real-time monitoring of leakage through real-time data collection and analysis of optical fiber network and demodulator, which means that once leakage occurs, the system can immediately issue an alarm, so that measures can be taken in time to deal with it.

[0060] Since the optical fiber network can transmit data over long distances, the present invention can realize remote monitoring, which reduces the frequency and cost of manual inspections and improves monitoring efficiency.

[0061] The present invention can adapt to various complex tunnel and underground engineering environments. The optical fiber sensor can be arranged axially and circumferentially along the tunnel wall to cover various key areas of the tunnel. In addition, the optical fiber sensor also has the characteristics of anti-electromagnetic interference and corrosion resistance, and can work stably in harsh environments.

[0062] The monitoring scheme of the present invention can be adjusted according to actual needs. For example, in active temperature field leak detection, the monitoring effect can be optimized by adjusting the position and power of the heating pipe; in passive temperature field leak detection, the laying position and number of optical cables can be adjusted according to the leakage situation.

[0063] In general, the method provided by the present invention integrates advanced sensing technology, data analysis algorithms and intelligent management methods, providing a new solution for tunnel leakage monitoring. This method can not only improve the safety and durability of tunnels, but also significantly reduce maintenance costs, which is of great significance for improving the overall quality and reliability of urban infrastructure. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Figure 1 It is a schematic diagram of passive temperature field leak detection of the present invention.

[0065] Figure 2 This is a schematic diagram of active temperature field leak detection of the present invention.

[0066] Figure 3 It is a schematic diagram of the optical fiber side leakage optical fiber arrangement of the present invention.

[0067] Figure 4 It is a structural diagram of the Fluke thermal imager of the present invention.

[0068] Figure 5 It is a schematic diagram of the interface for importing IS2 files of the present invention.

[0069] Figure 6 It is another schematic diagram of the interface for importing IS2 files of the present invention.

[0070] Figure 7 Another schematic diagram of the interface for editing infrared thermal images of the present invention.

[0071] Figure 8 This is an infrared thermal image of a serious water seepage area of ​​the present invention.

[0072] Fig. 9 This is an infrared thermal image of water stains on the wall surface of the water seepage area of ​​the present invention.

[0073] Fig.10 This is an infrared thermal image of water accumulation in the water seepage area of ​​the present invention.

[0074] Fig.11 This is an infrared thermal image of a serious water seepage area of ​​the present invention, with water flowing out of the surface.

[0075] Fig.12 This is an infrared thermal image of the cracked area of ​​the present invention, a thermal image of the water seepage area of ​​Dapu Road Tunnel.

[0076] Fig.13 It is the visible light spectrum, infrared thermal imaging diagram at IR003287 and isotherm diagram of the present invention.

[0077] Fig.14 It is the visible light spectrum, red thermal imaging diagram at IR003297 and isotherm diagram of the present invention.

[0078] Fig.15 It is the visible light spectrum, infrared thermal image at IR003314 and isotherm picture of the present invention.

[0079] Fig.16 It is the visible light spectrum, infrared thermal image at IR003326 and isotherm picture of the present invention.

[0080] Fig.17 It is the visible light spectrum, infrared thermal image at IR003336 and isotherm picture of the present invention.

[0081] Fig.18 The visible light spectrum, infrared thermal image at IR003342 and isotherm image of the present invention

[0082] Fig.19 The figure is a flow chart of the method of the present invention.

[0083] Fig. 20 This is a logic block diagram for identifying temperature anomaly points of the present invention.

[0084] Fig.21 It is a logic block diagram of leakage assessment of the present invention. DETAILED DESCRIPTION

[0085] In order to further explain the technical means and effects of the present invention to achieve the predetermined invention purpose, the specific implementation methods, structures, features and effects of the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments thereof. In the following description, different "one embodiment" or "another embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures or characteristics in one or more embodiments may be combined in any suitable form.

[0086] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0087] Example 1

[0088] See also Figure 1-21 The present invention discloses a tunnel leakage identification method based on optical fiber sensing. The method realizes real-time and accurate monitoring of tunnel leakage by laying an optical fiber sensing network on the tunnel wall.

[0089] Specifically, the method of the present invention comprises the following steps:

[0090] First, the temperature data collected by the optical fiber sensing network arranged along the tunnel wall is obtained. Preferably, the optical fiber sensing network includes longitudinal armored optical fibers arranged axially and circumferentially along the tunnel wall, and optical fibers arranged circumferentially at the tunnel joints. This arrangement can achieve full coverage of the entire tunnel surface, especially focusing on monitoring joints prone to leakage.

[0091] Next, based on the acquired temperature data, the temperature anomaly points are identified. In one embodiment of the present invention, the point where the temperature deviation exceeds a preset threshold (such as 3°C) can be identified as a temperature anomaly point by comparing the current temperature with the historical average temperature. The threshold here can be adjusted according to the specific tunnel environment and requirements. For example, in areas with large temperature changes, the threshold can be appropriately increased to 5°C.

[0092] Then, the potential leakage point is determined based on the location of the temperature anomaly point and the temperature change characteristics. For example, if multiple temperature anomaly points are detected continuously within a certain range (such as 1 square meter), and the temperature of these points is lower than the surrounding area, it can be determined that there is a potential leakage in the area. This method can also be combined with factors such as temperature change rate for comprehensive judgment to improve the accuracy of identification.

[0093] Please refer to Figure 13-18 , which are the visible light spectrum, thermal imaging pictures and isothermal pictures of different leakage areas in Dapu Road Tunnel. It can be seen from the figure that the leakage area is highly similar to the low-temperature area in the thermal imaging picture, and the lowest temperature point in the leakage area can be determined from the isothermal picture.

[0094] Finally, a leak identification result is generated, which includes the location information of the potential leak point. This can be a detailed report, including the precise coordinates of the leak point, the degree of temperature anomaly, etc., to facilitate subsequent repairs and treatments.

[0095] In order to improve the quality of temperature data collection, the present invention also proposes a technical solution of using a special clamp to fix the longitudinal armored optical fiber and the circumferential optical fiber tightly to the tunnel wall. This fixing method can minimize the interference of environmental noise and improve the accuracy of temperature measurement. Preferably, a clamp made of elastic material can be used to ensure close contact between the optical fiber and the wall without causing damage to the optical fiber.

[0096] A significant advantage of the method of the present invention is its high sensitivity and real-time performance. Through distributed optical fiber sensing technology, continuous monitoring of the entire tunnel can be achieved to detect potential leakage problems in a timely manner. Compared with traditional manual inspections, this method can greatly improve detection efficiency and accuracy, and reduce labor costs and safety risks.

[0097] In addition, this method has good adaptability. By adjusting parameters such as temperature anomaly judgment threshold and leakage judgment algorithm, it can adapt to different types of tunnels and different environmental conditions. For example, in areas with abundant groundwater, the sensitivity of leakage judgment can be reduced to avoid too many false alarms.

[0098] In general, the present invention provides an efficient and reliable method for identifying tunnel leakage, which is of great significance for improving the safety of tunnels and extending their service life.

[0099] In a preferred embodiment of the present invention, in order to improve the accuracy of temperature data, the method further includes obtaining tunnel ambient temperature data, and correcting the temperature data collected by the optical fiber sensing network based on the ambient temperature data. This step can effectively eliminate the influence of ambient temperature changes on leakage identification. Specifically, a number of ambient temperature sensors can be set at different locations in the tunnel to collect ambient temperature data regularly. Then, the temperature distribution model of the entire tunnel is calculated using an interpolation algorithm, and it is used as a benchmark to correct the temperature data collected by the optical fiber.

[0100] For example, the following formula can be used for temperature correction:

[0101] T corrected =T measured -(T environment -T baseline )

[0102] Among them, T corrected is the corrected temperature, T measured is the original temperature measured by the optical fiber, T environment is the current ambient temperature, T baseline In this way, the interference of factors such as seasonal changes and day and night temperature differences can be effectively eliminated, and the accuracy of leakage identification can be improved.

[0103] The method of the present invention also introduces active temperature field leak detection technology, which is a powerful supplement to passive monitoring. In the active leak detection process, the temperature distribution of the tunnel wall is first changed by an artificial heating system. Preferably, electric heating wires or hot water pipes can be used as heating elements and evenly arranged along the tunnel wall. The heating system can be started regularly or irregularly as needed, for example, once a week or when a leak is suspected.

[0104] Active temperature field leak detection is to use artificial heating to heat the soil and concrete wall around the joints of the continuous wall facing the soil surface. At this time, the water temperature around the joints outside the wall is relatively high. Before the foundation pit is excavated, when the foundation pit is not dewatered, the soil outside the wall is quickly heated. Due to the poor thermal conductivity of the reinforced concrete wall, the temperature inside the wall will not rise significantly. After heating for a period of time, the temperature inside the wall will slowly rise. If there are defects in the wall joints, the water inside and outside the wall are connected at the joints. If water flows into the wall at this time, the wall can detect abnormal temperature rise. During the excavation of the foundation pit, it is necessary to dewater around the foundation pit. If there are defects in the joints, groundwater outside the wall flows into the wall. At this time, the temperature measuring optical cable inside the wall can detect that the temperature rise in the leakage area is slow, because the groundwater outside the wall continues to flow into the pit, and the heating efficiency of the heating system outside the wall is limited. Therefore, the active temperature field leak detection is more effective during the foundation pit dewatering process after the underground continuous wall is built. The artificial heating method uses circulating hot water in heating pipes. The 1.2-inch galvanized steel pipe is fixed to the steel bars on the soil surface of the steel cage on both sides of the continuous wall joint. The optical cable is fixed to the steel bars on the pit surface and soil surface of the steel cage on both sides of the wall joints. It is hoisted into the trench section together with the steel cage.

[0105] After heating, this method collects temperature data after heating and identifies temperature anomalies based on these data. The advantage of this active heating method is that it can significantly enhance the temperature contrast between the leakage point and the surrounding area. The normal area will show a relatively uniform temperature distribution after heating, while the leakage area will have a significant difference in heating rate and final temperature from the surrounding area due to the presence of moisture.

[0106] For example, the following criteria can be set: if the temperature rise in a certain area is less than 80% of the average value of the surrounding areas, or its final temperature is more than 2°C lower than the average value of the surrounding areas, it will be marked as a potential leakage point. These parameters can be adjusted according to actual conditions to achieve the best detection effect.

[0107] In order to achieve efficient active heating, in one embodiment of the present invention, the artificial heating system includes a heating pipe arranged along the tunnel wall and a circulating hot water device connected thereto. This design can ensure the uniformity and controllability of heating. The heating pipe can be made of corrosion-resistant and thermally conductive materials (such as stainless steel or copper pipes), and the diameter is usually between 20-30 mm. The circulating hot water device can select an appropriate power according to the scale and requirements of the tunnel, generally in the range of 10-50 kW.

[0108] In addition, the present invention also proposes a passive temperature field leak detection method as a supplement to active leak detection. This method uses a self-heating armored temperature measuring optical cable as a temperature sensor to collect temperature data during the tunnel foundation pit dewatering process. The characteristic of the self-heating armored temperature measuring optical cable is that it can generate heat by itself when powered on and can measure temperature at the same time. This design cleverly combines the advantages of active heating and passive monitoring.

[0109] Passive temperature field leak detection does not change the temperature of the environment around the continuous wall joint, but raises the temperature of the optical fiber itself. This solution uses a self-heating armored temperature measurement optical cable to achieve the test purpose. Before the excavation of the foundation pit, when there is no artificial precipitation, the optical cable is laid longitudinally in the concrete protective layer on both sides of the joint of the continuous wall near the underground wall facing the pit surface. At this time, unless there is no protective layer outside the optical cable and it is only exposed to the joint defect position, a significant temperature drop will be detected. During the excavation of the foundation pit, the groundwater outside the wall will flow into the pit from the leakage position during the precipitation of the foundation pit. The heating optical cable laid near the joint leakage position will produce abnormal low temperature because the heat is carried away by the water flow. The passive temperature field leak detection test effect is more significant when precipitation is in the process of foundation pit excavation.

[0110] During the dewatering process of the tunnel foundation pit, if there is leakage, the water flow will take away the heat of the optical cable, causing the local temperature to drop. By analyzing these temperature anomalies, the leakage location can be effectively identified. Preferably, a temperature gradient threshold can be set. For example, if the temperature at a certain point is more than 1.5°C lower than that of the adjacent area, and this temperature difference lasts for more than 30 minutes, it is determined that there may be a leakage.

[0111] The advantage of this passive leak detection method is that it can monitor continuously for a long time without the need for additional heating equipment, has low energy consumption, and is suitable for large-scale and long-term leakage monitoring. Especially during tunnel construction or maintenance, this method can provide real-time leakage information, providing an important basis for engineering decision-making.

[0112] By combining active and passive leak detection technologies, the method of the present invention can comprehensively and accurately identify tunnel leakage, providing strong technical support for the safe operation and maintenance of the tunnel. In a further embodiment of the present invention, in order to more comprehensively evaluate the tunnel leakage, the method also includes determining the leakage range based on the spatial distribution characteristics of the temperature anomaly points, and evaluating the leakage degree according to the size of the leakage range. This step can provide tunnel maintenance personnel with more detailed and valuable information, which is helpful for formulating targeted maintenance strategies.

[0113] Specifically, the method first analyzes the spatial aggregation degree of temperature anomaly points. Preferably, a density clustering algorithm such as DBSCAN (Density-Based Spatial Clustering of Applications with Noise) can be used to identify the clustered areas of temperature anomaly points. In one embodiment of the present invention, the clustering parameter ε (neighborhood radius) can be set to 0.5 meters and MinPts (minimum number of points) can be set to 3. This means that if there are at least 3 temperature anomaly points within a radius of 0.5 meters, these points are considered to belong to the same leakage area.

[0114] After determining the leakage range, the method further evaluates the leakage severity. The evaluation criteria can be based on the area of ​​the leakage range and the degree of temperature anomaly. For example, the leakage severity index can be calculated using the following formula:

[0115] S=A×ΔT×w

[0116] Among them, S is the leakage severity index, A is the leakage range area (square meters), ΔT is the average temperature anomaly value in the area (degrees Celsius), and w is the weight coefficient (which can be adjusted according to the specific tunnel conditions, the default value is 1).

[0117] According to the calculated severity index, the leakage degree can be divided into different levels. For example:

[0118] S<5: slight leakage, requiring regular observation;

[0119] 5≤S<20: Moderate leakage, it is recommended to arrange maintenance in the near future;

[0120] S≥20: severe leakage, requiring immediate treatment;

[0121] This quantitative assessment method can help managers better allocate maintenance resources and prioritize the most urgent leaks.

[0122] In order to improve the accuracy and reliability of leakage identification, the method of the present invention also introduces a normal temperature distribution model based on historical data. In practical applications, the temperature distribution in the tunnel usually shows some regular changes, such as changes with depth, season or diurnal cycle. By establishing such a model, abnormal temperature changes can be identified more accurately.

[0123] Specifically, this method first collects long-term temperature monitoring data, usually at least one year of data is required to cover all seasonal changes. Then, a prediction model of the normal temperature distribution of the tunnel is established using time series analysis methods such as the autoregressive integrated moving average model (ARIMA) or the long short-term memory network (LSTM).

[0124] During real-time monitoring, this method compares the current temperature data with the normal temperature distribution predicted by the model. If the difference between the actual temperature and the predicted temperature at a point exceeds a preset threshold (e.g., 3 standard deviations), it is marked as an abnormal temperature change. This method can effectively reduce false alarms caused by normal temperature fluctuations and improve the accuracy of leak identification.

[0125] Finally, in order to intuitively display the leakage identification results and issue an alarm in time, the method of the present invention also includes the functions of generating a visual leakage map and triggering an alarm signal. The visual leakage map is a powerful tool that can help managers quickly understand the overall leakage status of the tunnel.

[0126] In a preferred embodiment of the present invention, the visual leakage map is displayed using a three-dimensional model, integrating information such as tunnel structure, leakage point location, leakage range and leakage degree. Leakage points can be represented by markers of different colors, for example, green for slight leakage, yellow for moderate leakage and red for severe leakage. The leakage range can be represented by a semi-transparent color block, and the color depth corresponds to the leakage degree.

[0127] In addition, the method also sets an alarm mechanism. When a serious leakage is detected, the system will automatically trigger an alarm signal. Preferably, a multi-level alarm mechanism can be set, for example:

[0128] Minor leakage: the system records but does not alarm;

[0129] Moderate leakage: Send reminder emails or text messages to management personnel;

[0130] Serious leakage: Immediately sound and light alarms are issued, and relevant personnel are notified through multiple channels (such as phone calls, text messages, emails, etc.);

[0131] This multi-level alarm mechanism ensures that managers receive important information in a timely manner while avoiding fatigue caused by too many low-level alarms.

[0132] In summary, the tunnel leakage identification method based on optical fiber sensing provided by the present invention realizes comprehensive, accurate and real-time monitoring of tunnel leakage by combining advanced sensing technology, data analysis algorithm and visual display. This method can not only improve the safety and durability of the tunnel, but also significantly reduce maintenance costs, providing an efficient and reliable solution for tunnel management.

[0133] It should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A tunnel leakage identification method based on optical fiber sensing, characterized in that ,include: The acquisition steps include: Obtain temperature data collected by a fiber-optic sensor network arranged along the tunnel wall; The processing steps include: Based on the temperature data, identifying temperature abnormal points; Determine potential leakage points according to the location of the temperature anomaly point and the temperature change characteristics; The output steps include: Generate a leakage identification result including the location information of the potential leakage point.

2. The method according to claim 1, characterized in that ,The acquisition step specifically includes: laying longitudinal armored optical fiber along the axial and circumferential directions of the tunnel wall; The optical fiber is laid in a circular manner at the tunnel joints; Temperature data is collected through the longitudinal armored optical fiber and the circumferential optical fiber.

3. The method according to claim 2, characterized in that , also includes: The longitudinal armored optical fiber and the circumferential optical fiber are fixed tightly to the tunnel wall using a clamp.

4. The method according to claim 1, characterized in that ,The processing steps also include: acquiring tunnel environment temperature data; Based on the tunnel environment temperature data, temperature correction is performed on the temperature data.

5. The method according to claim 1, characterized in that , the processing steps also include: using an active temperature field leak detection method, including: Change the temperature distribution of the tunnel wall through artificial heating system; Collect temperature data after heating; Based on the temperature data after heating, temperature abnormality points are identified.

6. The method according to claim 5, characterized in that ,The artificial heating system includes: a heating pipe arranged along the tunnel wall; A circulating hot water device connected to the heating pipe.

7. The method according to claim 1, characterized in that , the processing steps also include: Passive temperature field leak detection method is used, including: Use self-heating armored temperature measuring optical cable as temperature sensor; Collect temperature data during tunnel pit dewatering; Based on the temperature data, temperature anomalies caused by water flow are identified.

8. The method according to claim 1, characterized in that , the processing steps also include: Determine the leakage range based on the spatial distribution characteristics of the temperature anomaly points; Evaluate the degree of leakage based on the size of the leakage range.

9. The method according to claim 1, characterized in that , the processing steps also include: Based on historical temperature data, a normal temperature distribution model of the tunnel is established; The current temperature data is compared with the normal temperature distribution model to identify abnormal temperature changes.

10. The method according to claim 1, characterized in that , the output step also includes: Generate a visual leakage map including the location, scope and extent of leakage; When a serious leak is detected, an alarm signal is triggered.

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