Highway subgrade catastrophe monitoring optical cable laying method

Abstract

The invention relates to the technical field of highway subgrade optical cable laying, in particular to a highway subgrade catastrophe monitoring optical cable laying method, which comprises the following steps of: S1, selecting a monitoring line at a position which is 40-50cm away from a roadside guardrail along a highway driving direction, and preprocessing pavement pit slots, upheaval packages and cracks on the line; s2, a modified milling machine with depth intelligent control and vision assistance is adopted for grooving, a depth excavation section of 3 cm and a filling section of 4 cm are set according to the type of the roadbed, and cleaning and drying are conducted after grooving; s3, laying sensing optical cables in a tension-free state by using a vehicle-mounted winch; s4, high-performance backfill coupling materials are poured in a layered mode and solidified; optical cable signals are monitored in real time through an optical time domain reflectometer S0 in the whole process, and abnormity is repaired in time. The subgrade catastrophe monitoring accuracy and the data reliability are improved, stable coupling of the optical cable and the subgrade is achieved, the construction rework rate and the maintenance cost are reduced, and the device is suitable for different subgrade types and various highway subgrade monitoring scenes.

Description

Technical Field

[0001] This invention relates to the field of optical cable laying technology for highway subgrade, specifically a method for laying optical cables for highway subgrade disaster monitoring. Background Technology

[0002] Currently, optical fiber sensing cables, with their advantages of distributed monitoring, strong anti-interference capabilities, and adaptability to complex environments, have been gradually applied to disaster monitoring of highway subgrades. However, existing optical fiber sensing cable deployment technologies still have many shortcomings in practical applications, making it difficult to meet the requirements of high-precision monitoring and long-term stable operation. The main problems are as follows: Firstly, the selection of monitoring routes lacks scientific standards, and road surface pretreatment is insufficient. Existing methods mostly rely on experience to determine the location of optical cables, with some routes being too close or too far from roadside guardrails. If they are too close, they are easily damaged by collisions during guardrail maintenance, while if they are too far, they are outside the main stress area of ​​the roadbed and cannot accurately capture roadbed deformation signals. At the same time, after the route is selected, the existing road surface defects such as potholes, bumps, and cracks are not treated in a targeted manner. When optical cables are laid directly in trenches, it is easy to cause uneven trenches and uneven stress on the optical cables. In the long term of operation, the optical cables may be damaged due to the expansion of road surface defects, affecting the continuity of monitoring. Secondly, the precision grooving process has defects, making it difficult to guarantee the quality of the grooves. On the one hand, most existing grooving equipment are ordinary cutting machines, lacking intelligent depth control and linear guidance functions. The grooving depth often deviates from the design value (e.g., the cut and fill sections are not differentiated). If it is too deep, it will easily damage the stable structure of the roadbed, while if it is too shallow, it will result in insufficient burial depth of the optical cable and greater impact from vehicle vibration. On the other hand, the cleaning and drying treatment after grooving is not standardized. Residual waste residue, dust or rainwater in the grooves not only affect the fit between the optical cable and the backfill material, but may also accelerate the aging of the outer sheath of the optical cable and shorten the life of the monitoring system. Third, the lack of tension control and real-time monitoring during the fiber optic cable laying process easily leads to cable damage. Current laying methods often involve manual dragging, making it difficult to avoid tension stretching of the cable, resulting in micro-bending of the internal optical fibers and increased signal attenuation. In some operations, the cable is not laid in the center of the trench bottom, but rather against the wall or bent, preventing the roadbed deformation from being evenly transmitted to the cable and causing distorted monitoring data. Furthermore, signal monitoring is not conducted simultaneously during the laying process; cable breakage or excessive attenuation is only discovered after construction is completed, requiring rework and re-digging of the trench, significantly increasing construction costs and time. Fourth, the coupling backfilling process is unreasonable, resulting in poor mechanical coupling effect. Existing backfill materials are mostly ordinary asphalt or concrete. Improper control of heating temperature and time can easily lead to insufficient carbonization or curing, resulting in insufficient strength of the backfill material. During grouting, one-time filling is often used without layered vibration to remove air bubbles. After curing, voids are easily generated, making it impossible for the optical cable to form a stable mechanical coupling with the roadbed. The signal loss is serious during the transmission of roadbed deformation, and the disaster early warning is delayed. At the same time, the shrinkage voids are not filled again after curing, and external rainwater and impurities can easily seep into the trench, corroding the optical cable or damaging the backfill structure, reducing the durability of the monitoring system. Fifth, existing technologies have poor adaptability and are difficult to meet the needs of different roadbed scenarios. For the differences between excavated sections (dense structure) and filled sections (prone to settlement) of roadbeds, the existing deployment methods have not adjusted the process parameters (such as trench depth and backfill material ratio), resulting in inconsistent monitoring accuracy of the same monitoring line in different roadbed sections. Moreover, some processes rely on customized equipment, which is complicated to operate and is limited in its promotion in different regions such as mountainous areas and plains. It is difficult to form a standardized construction process, which restricts the widespread application of optical fiber sensing cable monitoring technology in the field of highway roadbeds.

[0003] In summary, existing optical cable deployment technologies for highway subgrade disaster monitoring have significant shortcomings in aspects such as route selection, precise trenching, optical cable deployment, and coupling backfilling. These shortcomings result in low monitoring accuracy, poor system stability, high construction costs, and insufficient adaptability, failing to meet the actual needs of long-term, precise disaster monitoring of highway subgrades. Therefore, developing a standardized, accurate, stable, and highly adaptable optical cable deployment method has become an urgent technical problem to be solved in the field of highway engineering monitoring. Summary of the Invention

[0004] The purpose of this invention is to provide a method for laying optical cables for monitoring disasters in highway subgrades, so as to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A method for deploying optical cables for monitoring disasters in highway subgrade includes the following steps: S1. Monitoring route selection: Select a monitoring route along the direction of traffic on the highway, 40-50cm away from the roadside guardrail; S2. Precision grooving: Using road grooving equipment, grooves are cut along the selected monitoring line to form a groove with a width of 1cm and a depth of 3-4cm; after grooving, the groove is cleaned and dried to ensure that the groove is clean and dry. S3. Fiber optic cable laying: Lay the sensing fiber optic cable at the bottom of the groove in a tension-free state; S4. Coupling backfill: After heating the high-performance backfill coupling material to a fluid state, it is poured into the groove containing the sensing optical cable and then cured, so that the sensing optical cable forms a mechanical coupling with the roadbed and pavement structure through the high-performance backfill coupling material. The depth of the trench is adjusted according to the type of roadbed: 3cm for the excavation section and 4cm for the embankment section.

[0006] As a preferred option, steps S3 and S4 also include a step S0: using an optical time domain reflectometer to monitor the deployment status of the sensing optical cable in real time; if an abnormal signal is detected, construction is suspended and the optical cable is repaired.

[0007] As a preferred option, in step S1, after selecting the monitoring line, the existing pavement defects on the line are pretreated, including the repair of potholes, bumps and cracks.

[0008] As a preferred option, in step S2, the road grooving equipment is a modified milling machine. This modified milling machine is equipped with a grooving depth intelligent control module and a binocular vision-assisted driving module to ensure the accuracy of the grooving depth and the straightness of the line.

[0009] As a preferred option, the modified milling machine is also equipped with a tool spray cooling device, which sprays water at a rate of 0.5 kg / m to cool the blades during the grooving process.

[0010] As a preferred embodiment, in step S2, the drying process is as follows: when construction is carried out after rain or under humid conditions, a powdered desiccant is applied into the groove. The main components of the desiccant are silica gel or calcium chloride. The reaction time is no more than 10 minutes. After absorbing water, it becomes a free-flowing granular form that is easy to clean.

[0011] As a preferred option, in step S3, a vehicle-mounted winch is used to lay the optical cable. The length of a single winch for the sensing optical cable is 2km, and the optical cable is kept in a slack state during the laying process.

[0012] As a preferred option, in step S4, the heating temperature of the high-performance backfill coupling material does not exceed 200°C, and the heating time does not exceed 30 minutes.

[0013] As a preferred option, in step S4, the grouting adopts a layered backfilling process: first, the fluid coupling material is poured into the groove to a depth of 2-3cm, and after it has initially solidified, the remaining part is poured until it is flush with the groove opening.

[0014] As a preferred approach, after the coupling material has fully cured, a full inspection of the backfill tank is carried out, and local voids caused by curing shrinkage are filled a second time.

[0015] As can be seen from the above technical solution provided by the present invention, the beneficial effects of the method for laying optical cables for monitoring disasters in highway subgrade provided by the present invention are: This invention optimizes and ensures monitoring accuracy through multi-stage technology. In step S1, the monitoring line is selected at a distance of 40-50cm from the roadside guardrail, and existing road surface potholes, bulges, and cracks are pre-treated to ensure that the line fits the key monitoring area of ​​the roadbed. In step S2, the trenching depth is set according to the roadbed type: 3cm for excavation sections and 4cm for filling sections. With the intelligent depth control and vision-assisted driving of the modified milling machine, the trenching accuracy deviation is controlled within 0.1cm, providing precise space for optical cable laying. In addition, step S0 uses an optical time domain reflectometer to monitor the optical cable signal in real time, promptly eliminating problems such as abnormal attenuation and reflection peak shift, avoiding data distortion caused by optical cable damage or positional deviation. Ultimately, this reduces the capture error of disaster information such as roadbed settlement and cracks, and the monitoring data is more consistent with the actual structural state. This invention ensures effective coupling between the optical cable and the roadbed through standardized processes. Step S3 uses a vehicle-mounted winch to lay the optical cable in a tension-free state, avoiding deformation damage caused by stress. Simultaneously, the optical cable is precisely positioned at the center of the trench bottom, ensuring uniform deformation transmission under stress. Step S4 involves layered injection of high-performance backfill coupling material. After the initial injection, air bubbles are removed by vibration, followed by a second injection until the trench opening is flush. Combined with 24 hours of complete curing and strength monitoring, the coupling material achieves a hardness of over 50 MPa and an adhesion strength to the optical cable of no less than 3 MPa, forming a tight mechanical connection structure. This coupling method allows roadbed deformation to be directly and losslessly transmitted to the sensing optical cable, avoiding signal delays or distortions due to insufficient coupling and improving the timeliness of disaster early warning. This invention constructs a full-process construction management and control system. Step S0 involves collecting the baseline curve before optical cable laying, real-time early warning during laying and backfilling (such as triggering audible and visual alerts for optical cable damage, and suspending work due to abnormal coupling material injection), and then retesting and confirming after repair, forming a closed loop of "monitoring-early warning-repair-verification". This can quickly locate and handle problems such as optical cable breakage and coupling material air bubbles, avoiding the retention of potential faults. Step S2 involves cleaning and drying after trenching, and Step S4 involves strict control of coupling material heating and curing parameters (temperature not exceeding 200℃, duration not exceeding 30 minutes), reducing material waste or structural damage caused by improper construction operations. At the same time, all construction data (such as abnormal locations and repair measures) are recorded in detail, facilitating later traceability and significantly reducing rework costs caused by construction errors. This invention enhances system durability through multi-dimensional protection. Step S2 involves cleaning and drying the grooves after slotting to prevent impurities and moisture residue from causing aging of the optical cable sheath. Step S4 uses high-performance backfill coupling material, which not only has high strength but also isolates the optical cable from external rain and dust erosion. Combined with secondary filling to eliminate solidification shrinkage gaps, this further improves the protective effect. Step S0 standardizes repair measures for abnormal optical cables, such as using special repair patches to treat outer sheath damage and controlling the attenuation value within 0.1dB after fusion splicing at fracture points, ensuring stable optical cable performance. These designs enable the monitoring system to withstand the effects of vehicle vibration and environmental temperature and humidity changes during long-term highway operation, reducing subsequent maintenance work such as optical cable replacement and coupling material repair, and lowering the total life-cycle cost. This invention possesses flexible roadbed adaptability; step S2 differentiates the trenching depth based on the structural differences between excavated and filled sections of the roadbed, meeting the monitoring needs of different roadbeds without adjusting the overall construction process; from route selection, trenching, optical cable laying to coupling backfilling, each step of the process is standardized (e.g., fixed trench width of 1cm, single optical cable length of 2km, and unified parameters for layered grouting of coupling material), the operation process is clear and easy to understand, and it does not rely on complex customized equipment. It is applicable to roadbed monitoring scenarios in different regions such as plains and mountains, and can be conveniently applied to both newly built highways and existing highway renovations, significantly improving the scope of technology promotion and practical value. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the steps involved in the deployment of optical cables for monitoring disasters in highway subgrade, according to the present invention. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0018] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific embodiments.

[0019] like Figure 1 As shown in the figure, this embodiment of the invention provides a method for deploying optical cables for monitoring disasters in highway subgrades, including the following steps: S1. Monitoring route selection: Select a monitoring route along the direction of traffic on the highway, 40-50cm away from the roadside guardrail; S2. Precision grooving: Using road grooving equipment, grooves are cut along the selected monitoring line to form a groove with a width of 1cm and a depth of 3-4cm; after grooving, the groove is cleaned and dried to ensure that the groove is clean and dry. S3. Fiber optic cable laying: Lay the sensing fiber optic cable at the bottom of the groove in a tension-free state; S4. Coupling backfill: After heating the high-performance backfill coupling material to a fluid state, it is poured into the groove containing the sensing optical cable and then cured, so that the sensing optical cable forms a mechanical coupling with the roadbed and pavement structure through the high-performance backfill coupling material. The depth of the trench is adjusted according to the type of roadbed: 3cm for the excavation section and 4cm for the embankment section.

[0020] In this embodiment, step S1 is based on the core requirements of highway subgrade disaster monitoring for coverage effectiveness, data accuracy, and construction safety. It involves scientifically selecting the monitoring route location, accurately locating the route coordinates, comprehensively investigating and repairing pavement defects, and ultimately identifying a baseline route that meets the monitoring functions and construction conditions. This provides a clear path for the subsequent precise trenching in step S2 and the fiber optic cable laying in step S3, ensuring from the source that the sensing fiber optic cable can stably and accurately sense the deformation and disaster signals of the subgrade structure, avoiding the impact of improper route selection or pavement defects on the monitoring effect. The detailed steps are as follows: Step S1-1 Preliminary Site Selection and Planning for the Line: With the dual core objectives of comprehensive sensing requirements for highway subgrade disaster monitoring and on-site construction operability, the preliminary site selection process was initiated. First, key constraints for site selection were established, using the highway's driving direction as the baseline axis, strictly limiting the horizontal distance between the monitoring line and the roadside guardrail to within a range of 40cm to 50cm. This distance range simultaneously achieves two core objectives: first, ensuring that the sensor fiber optic cable effectively covers the main subgrade structure after deployment, accurately capturing disaster information such as settlement and cracks within the subgrade, thus guaranteeing the validity of the monitoring data; second, avoiding disturbance zones caused by highway vehicle tracks. The scope of routine maintenance of the area and roadside guardrails should be expanded to reduce the risk of optical cables being damaged by vehicles or maintenance work during subsequent operation. During the site selection process, it is necessary to simultaneously investigate inherent obstacles on the route, including roadside guardrail posts, road drainage wells, roadbed expansion joints, and shoulder ancillary structures. The locations of obstacles should be marked on-site, and the route should be fine-tuned according to the distribution of obstacles to ensure that the adjusted route remains continuous and uninterrupted, and that the horizontal distance between the route and various obstacles is not less than 10cm, so as to avoid equipment jamming or optical cable damage during subsequent trenching construction and optical cable laying. Step S1-2: Precise route positioning and coordinate acquisition: A GNSS real-time dynamic positioning system was used for precise route positioning to ensure the accuracy of subsequent construction. First, nationally established surveying benchmarks along the highway were selected as positioning references. The positioning equipment parameters were calibrated using a system calibration program to ensure positioning errors were kept within acceptable limits. Then, along the initially selected route, continuous coordinate data was collected at fixed intervals of 1 meter. At each interval, three-dimensional coordinate data for one point was collected, including longitudinal mileage coordinates (X-axis), lateral offset coordinates (Y-axis) in the plane coordinate system, and road surface elevation (Z-axis) in the elevation coordinate system, forming a complete... A 3D route coordinate dataset is required. During the acquisition process, the positioning accuracy needs to be verified in real time. The single acquisition error of the plane coordinates must not exceed 5cm, and the single acquisition error of the elevation coordinates must not exceed 3cm. If the error of a certain acquisition point exceeds the threshold, the acquisition operation of that point must be repeated, and the original abnormal data must be removed. After the acquisition is completed, the 3D coordinate dataset is imported into professional surveying software to generate a visualized route trajectory map. The coordinate information of the route direction, turning points, and key control points (such as obstacle avoidance points and roadbed type conversion points) is clearly marked, providing a clear position benchmark for the precise trenching in the subsequent step S2. Step S1-3: Comprehensive investigation of existing road surface defects: Based on the precisely located route trajectory, a comprehensive investigation of existing pavement defects within the route coverage area is conducted using a combination of manual inspection and portable pavement inspection equipment. The defects investigated primarily include three types: potholes, bulges, and cracks. For potholes, a steel tape measure is used to measure and record their length, width, and maximum depth, while also marking the relative position of the pothole edges to the route trajectory. For bulges, a pavement smoothness meter is used to measure the maximum height of the bulge protruding from the pavement, and the lateral and longitudinal extent of the bulge's influence is delineated. For cracks, a crack width meter is used to measure the maximum width of the crack, a tape measure is used to record the total length of the crack, and the direction of the crack's extension (e.g., longitudinal, lateral, or diagonal) is marked. During the investigation, the location information of each defect is precisely correlated with the three-dimensional route coordinates generated in steps S1-2 to establish a defect location distribution map, clearly defining the coordinate range, defect type, and severity level (e.g., mild, moderate, severe) of each defect area, providing detailed data support for subsequent targeted defect pretreatment. Step S1-4: Pre-treatment of road surface defects by classification: For different types and levels of road surface defects identified during the investigation, categorized and graded pretreatment measures were implemented to ensure that the road surface quality within the route area met the requirements for subsequent trenching and optical cable laying. Pothole Repair: For minor potholes (depth less than 3cm), first use a road cutter to cut along the edge of the pothole to form a regular rectangular boundary, with the cutting depth 1cm greater than the maximum depth of the pothole. Then, use a high-pressure blower to remove loose debris, dust, and accumulated water from the pothole, ensuring that the pothole walls and bottom are clean and dry. Use hot-mix asphalt mixture for layered backfilling, with each layer controlled between 3cm and 5cm in thickness. After each layer of backfilling, use a small vibratory roller for compaction, ensuring a compaction degree of over 95%. Finally, backfill until it is flush with the original road surface. For moderate and severe potholes (depth greater than or equal to 3cm), after cutting and cleaning, first lay a layer of emulsified asphalt tack coat at the bottom of the pothole, then backfill and compact the hot-mix asphalt mixture in layers to ensure that the strength of the repaired pothole is consistent with the original road surface. Bump treatment: A small milling machine is used to mill the protruding part of the bump. During the milling process, the elevation monitoring module of the equipment monitors the road surface elevation in real time and adjusts the milling depth according to the monitoring data to ensure that the flatness deviation of the road surface after milling does not exceed 2mm. The connection between the milled area and the surrounding road surface is smoothed by manual grinding to avoid step-like height differences. Crack Treatment: For minor cracks less than 3mm wide, first use a high-pressure gas spray gun to remove dust, debris, and other impurities from the crack. After the crack is dry, use a special caulking gun to inject road sealant into the crack, ensuring that the sealant fills the crack and adheres tightly to the crack wall. After injection, use a scraper to smooth out any excess sealant at the crack opening. For moderate and severe cracks 3mm or wider, first use a road grooving machine to groove and widen the crack along its direction. The grooving width should be controlled between 1cm and 1.5cm, and the grooving depth between 2cm and 3cm. After grooving, use a high-pressure blower to clean the impurities in the grooving, then inject sealant. After the sealant has cured, smooth the surface again to ensure it is flush with the road surface. Steps S1-5: Final confirmation and filing of the route: After completing the pretreatment of road surface defects, a second comprehensive inspection of the monitoring line is conducted, focusing on verifying three key aspects: First, the quality of the pretreated road surface, using a road surface smoothness meter to check the smoothness of the road surface within the line area, ensuring there are no obvious bumps, depressions, or loose areas; second, the completeness of defect repair, checking whether all identified defects have been treated, and whether the appearance and strength of the repaired areas meet the requirements; and third, the continuity of the line direction, confirming whether the adjusted line remains continuous, and whether the distance to the roadside guardrail is always within the range of 40cm to 50cm. Simultaneously, the matching degree between the line coordinates and the actual road surface is verified again using a GNSS real-time dynamic positioning system, ensuring no line deviation or omissions. After confirming that all indicators meet the requirements, a formal monitoring line technical document is generated. The document includes a three-dimensional coordinate dataset, a line trajectory diagram, a defect treatment record table (including defect location, type, treatment method, and acceptance results), and a road surface quality verification report. This technical document serves as the formal basis for the subsequent step S2 precision trenching construction, completing the entire process of monitoring line selection.

[0021] In this embodiment, step S2, based on the monitoring line and pre-treated road surface conditions determined in step S1, involves precisely excavating grooves of the required dimensions using specialized grooving equipment. These grooves are then cleaned and dried to provide a clean, dry, and sized space for the tension-free installation of the sensing optical cable in step S3. Simultaneously, through precise equipment control and process optimization, the grooving process ensures that the original roadbed structure is not damaged, laying the foundation for the subsequent mechanical coupling between the sensing optical cable and the road surface. The detailed steps are as follows: Step S2-1: Debugging and configuration of the slotting equipment: First, the equipment configuration and parameter debugging of the modified milling machine are completed to ensure that the equipment meets the requirements for precise grooving. This modified milling machine needs to be equipped with three core functional modules: the first is an intelligent grooving depth control module, which uses a built-in displacement sensor and pressure feedback unit to collect real-time cutting depth data of the milling cutter, compares it with a preset depth value, and automatically adjusts the cutter lifting height to control the depth deviation to no more than 0.1cm; the second is a binocular vision-assisted driving module, which uses high-definition cameras on both sides of the machine to collect road surface images, and performs real-time image matching with the trajectory map generated in step S1, leading to… The guiding equipment travels in a straight line along the monitoring line to avoid deviation from the line shape and ensure that the deviation between the grooving trajectory and the planned line does not exceed 2cm; the third type is the tool spray cooling device, which includes a water tank, a high-pressure spray pump and a flow control valve. During debugging, the spray flow rate needs to be set to 0.5kg / m to ensure that the tool can be continuously cooled during the cutting process, avoiding accelerated tool wear or carbonization of the road surface material due to high temperature; after all modules of the equipment are debugged, a no-load test run is carried out to check the operating status of each module. After confirming that the depth control accuracy, travel guidance accuracy and spray flow rate all meet the requirements, it enters the ready-to-work state; Step S2-2: Precise setting of slotting parameters: Based on the subgrade type corresponding to the monitoring line, the depth and width parameters of the trench are set. First, the trench width parameter is set to a fixed value of 1cm, which is achieved by replacing the special milling cutter of the modified milling machine. The cutter width must be perfectly matched with the trench width requirement to ensure that the sidewall of the trench is flat and without protrusions after excavation. Then, the trench depth parameter is adjusted according to the subgrade type. If the monitoring line is located in the excavation section of the subgrade, the subgrade structure has a high density, so the trench depth is set to 3cm. If the monitoring line is located in the embankment section of the subgrade, the subgrade may have a risk of future settlement. To ensure that the sensing cable can detect deep deformation, the trench depth is set to 4cm. After the parameters are set, the depth data is entered into the storage unit of the intelligent control module for trench depth. The module automatically converts the set depth into control commands for the cutting tool lifting and lowering, providing a parameter benchmark for subsequent trenching operations. Step S2-3: Precise trenching along the route: The modified milling machine is started and grooving is carried out along the monitoring line determined in step S1. During the operation, the binocular vision-assisted driving module captures road surface images in real time. When the machine is detected to deviate from the planned line, it automatically sends a correction signal to the steering system to adjust the machine's direction and keep the machine traveling in a straight line along the line. The intelligent control module for grooving depth continuously monitors the cutting depth of the cutter, collecting depth data every 10cm. If the depth is found to exceed the set range, such as the depth of the excavation section being greater than 3.1cm or less than 2.9cm, the tool lifting adjustment is immediately triggered to pull the depth back to the set range. At the same time, the tool spray cooling device is activated, spraying cooling water onto the milling cutter at a flow rate of 0.5kg / m. The water flow evenly covers the cutting surface of the cutter, carrying away the heat generated by cutting and keeping the tool's working temperature below 80℃ to avoid overheating and a decrease in cutting efficiency. Grooving operations must be carried out continuously. If the operation is interrupted due to equipment failure or road obstacles, the interruption position must be confirmed by GNSS positioning after restarting. The connection with the already grouted section must overlap by 5cm to ensure that the groove is continuous and without gaps. Step S2-4: Cleaning the inside of the groove: After a section of the grooving operation is completed and the single-section length does not exceed 100 m, immediately clean the groove to remove loose waste residue, dust, and debris in the groove. The cleaning adopts a combined process of high-pressure blowing and negative-pressure dust collection. First, use a high-pressure blower with the air pressure set at 0.8 MPa and blow along the length direction of the groove to blow the fine dust at the bottom and side walls of the groove to the groove opening. Subsequently, use a handheld negative-pressure dust collector to thoroughly suck out the waste residue and dust at the groove opening. The suction port of the dust collector needs to move along the bottom of the groove to ensure that there are no particulate impurities with a particle size greater than 0.5 mm in the groove. After cleaning, check the cleanliness by combining visual inspection and measuring with a steel ruler. If there is no obvious dust or waste residue accumulation on the bottom and side walls of the groove visually and no visible stains on the steel ruler after wiping the bottom of the groove, it is determined that the cleaning is qualified. If there are areas with incomplete cleaning locally, the blowing and dust collection operations need to be repeated until the cleanliness requirements are met. Step S2-5 Control of the dry state of the groove: Perform targeted drying treatment on the groove according to the humidity of the construction environment. If it is sunny during construction and the moisture content of the road surface is less than 5%, adopt the natural air-drying method and let it stand for at least 2 hours. Use a moisture content detector to measure the moisture content of the road surface material at the bottom of the groove in real time. When the moisture content drops below 3%, it is determined that the drying is qualified. If it is after rain or in a humid condition and the moisture content of the road surface is greater than or equal to 5%, powder-like desiccant needs to be released into the groove. The main components of the desiccant are silica gel or calcium chloride. When releasing, it needs to be evenly spread along the length direction of the groove, and the spreading amount is 20 g / m to ensure that the desiccant can fully cover the bottom of the groove. The reaction time between the desiccant and the moisture in the groove does not exceed 10 minutes. After the reaction, the desiccant becomes flowing granular. At this time, a small scraper needs to be used to scrape out the granular desiccant from the groove to avoid residue affecting the subsequent optical cable laying. After scraping, use the moisture content detector to measure the moisture content at the bottom of the groove again and confirm that it has dropped below 3% to complete the drying treatment. Step S2-6 Acceptance and correction of grooving quality: A comprehensive quality inspection was conducted on the cleaned and dried trenches. The inspection criteria included three items: First, the trench width and depth. Using vernier calipers with an accuracy of 0.02cm, a test point was selected every 20m along the trench length to measure the trench width and depth. The trench width should remain stable at 1cm, with a deviation not exceeding 0.05cm. The trench depth in excavated sections should be between 2.9cm and 3.1cm, and in filled sections, it should be between 3.9cm and 4.1cm. Second, the trench alignment. The trench direction was measured using a string line method, with a nylon string stretched along the trench. First, tighten both ends of the trench opening. The maximum distance between the measuring line and the edge of the trench opening should not deviate by more than 2cm. Second, check the condition inside the trench. Visually inspect the bottom of the trench to ensure it is flat without obvious undulations and free of residual waste, desiccant, or water. If any test point does not meet the requirements, it needs to be corrected accordingly. If the trench width or depth is not up to standard, use a small handheld milling machine to cut or sandpaper to adjust it. If the line is off, re-excavate along the correct trajectory to correct it. If the condition inside the trench is not up to standard, clean and dry it again. Only after all test points are up to standard can you proceed to the next step.

[0022] In this embodiment, step S3 is based on the compliant groove cleaned and dried in step S2. Using specialized deployment equipment, the sensing optical cable is precisely laid in the groove bottom in a tension-free state, ensuring the cable's stable position, intact appearance, and absence of stress damage. This provides a prerequisite for effective mechanical coupling between the high-performance backfill coupling material and the roadbed / pavement after the subsequent step S4, ensuring the sensing optical cable can continuously and accurately sense deformation and catastrophic signals of the roadbed structure. The detailed steps are as follows: Step S3-1: Preparation of sensor optical cables and deployment equipment: First, prepare the sensor fiber optic cable and vehicle-mounted winch. Take out a 2km long sensor fiber optic cable from a single reel and lay it flat on a level road surface. Inspect the cable's appearance to ensure the outer sheath is free of damage, scratches, bulges, or other defects, and that the connectors at both ends are intact and secure. Next, check the vehicle-mounted winch's operation. The winch must be equipped with a tension buffer device and a speed adjustment module. During testing, start the winch under no-load to check if the cable winding and unwinding functions are smooth. Then, set the unwinding tension threshold using the tension buffer device (set it to near-zero tension to ensure no pulling force is applied to the fiber optic cable during unwinding). Simultaneously, adjust the winch's unwinding speed to 0.5m / s to ensure a uniform and stable unwinding process. If any defects are found in the sensor fiber optic cable during preparation, replace it immediately. If the vehicle-mounted winch malfunctions, repair and adjust it to normal operation before commencing deployment. Step S3-2: Path positioning and calibration: Using the groove that passed the acceptance test in step S2 as a benchmark, the positioning calibration of the deployment path is carried out; the coordinates of the groove's starting point are read using a GNSS positioning device, and the cable release port of the vehicle-mounted winch is moved to be directly above the groove's starting point. The winch position is adjusted so that the cable release port is aligned with the groove's center; then, along the groove's length, a pair of positioning marker stakes are set on both sides of the groove opening every 50m. A thin nylon line is stretched from the top of the marker stake, with the center line of the thin line coinciding with the groove's center line, forming a visual deployment guide line; at the same time, a small laser locator is installed at the cable release port of the vehicle-mounted winch, and the laser beam is projected onto the guide line to ensure that the optical cable can enter the groove along the guide line direction during the cable release process, avoiding path deviation; after calibration, the alignment accuracy of the cable release port, laser beam, and groove's center line is checked again. If the deviation does not exceed 0.3cm, the calibration is considered qualified; Step S3-3 Tension-free optical cable laying operation: Start the vehicle-mounted winch to begin laying the optical cable, strictly controlling the winch's operating parameters during the process. Lay the cable at a uniform speed of 0.5 m / s, while a designated person follows along the groove to observe and monitor the status of the sensor cable in real time. After the sensor cable is released from the winch, it should fall naturally into the groove, ensuring that the cable is slack at the bottom of the groove, with a sag of no more than 1 cm per 10 m length, and no tension or strain. If the cable gets stuck at the groove opening or rubs against the side wall of the groove, stop the vehicle-mounted winch immediately, manually lift the cable to adjust its position, and avoid damage to the outer sheath caused by local tension due to jamming. Laying a single reel of cable should be continuous. If the process is paused due to a brief equipment malfunction, manually pull the cable back 50 cm before restarting to eliminate any slight tension that may have occurred during the pause, and then continue laying the cable. Step S3-4: Position adjustment within the sensor optical cable trough: After laying 50m of sensor fiber optic cable, adjust its position within the trench. Use a small plastic scraper or tweezers to gently move the cable and position it at the center of the trench bottom. Since the trench width is 1cm, ensure that the distance between the cable and the trench sidewalls is uniform, 0.5cm on each side, without any sticking to the wall, bending, twisting, or overlapping. Be gentle during adjustment to avoid scratching the cable's outer sheath. If a slight bend is found, slowly stretch both ends of the cable to allow the bend to straighten naturally before readjusting it to the center of the trench bottom. After adjustment, measure the deviation between the cable center and the trench center with a steel ruler. A deviation of no more than 0.3cm indicates the position is acceptable. Step S3-5: Immediate acceptance of installation quality: After each 100m of sensor fiber optic cable is laid, an immediate quality inspection is conducted. The inspection includes four core components: 1) Visual inspection: Each section of the fiber optic cable's outer sheath is checked for defects such as damage, scratches, and cracks. 2) Tension inspection: The middle of the fiber optic cable is gently pulled; if there is no noticeable tension and the cable returns to a relaxed state after release, it is considered to have no tension. 3) Position inspection: A test point is selected every 20m along the groove's length, and the deviation between the cable's center and the groove's center is measured with a steel ruler; the deviation at all test points should not exceed 0.3cm. 4) Splice reservation inspection: When a single 2km reel of fiber optic cable is about to be laid, the cable end is led out to the outside of the groove end, reserving a 1m length for splice welding. This reserved section must be neatly coiled and protected to avoid crushing damage. If any problems are found during inspection, such as excessive cable position deviation, it is immediately adjusted with tools. If the outer sheath is damaged, the damaged section of cable must be cut, a new section re-welded, and the laying process continued until the inspection is passed.

[0023] In this embodiment, step S4 is based on the tension-free optical cable laid at the bottom of the groove in step S3. Through heating, pouring, and curing the high-performance backfill coupling material, the optical cable forms a stable mechanical coupling with the roadbed and pavement structure via the high-performance backfill coupling material. This ensures the structural integrity of the groove after backfilling, providing structural support for the accurate transmission of deformation signals by the optical cable during subsequent roadbed disaster monitoring, and preventing data distortion due to insufficient coupling. The detailed steps are as follows: Step S4-1: Preparation and testing of high-performance backfill coupling material: First, prepare the high-performance backfill coupling material. According to the preset formula, pour the coupling material raw materials (including matrix material, curing agent, reinforcing agent, etc.) into a dedicated mixing device. Start the device for uniform mixing, setting the mixing speed to 100 r / min and the mixing time to 15 minutes to ensure the raw materials are fully integrated without particle agglomeration. After mixing, conduct preliminary testing on the high-performance backfill coupling material. The testing includes two aspects: first, visual inspection, observing that the coupling material is a uniform paste without obvious impurities, lumps, or stratification; second, initial viscosity testing, using a viscometer to measure the viscosity of the coupling material, which must be controlled below 500 mPa·s to ensure smooth flow after subsequent heating. If the test reveals lumps or excessive viscosity, restart the mixing device and extend the mixing time by 5 minutes, then test again until the requirements are met. Step S4-2: Heat treatment of high-performance backfill coupling material: The qualified high-performance backfill coupling material is transferred to a dedicated heating device, and the heating program is started for temperature control. During the heating process, the temperature of the coupling material is monitored in real time by the built-in temperature sensor to ensure that the temperature is always controlled within the range of not exceeding 200℃. At the same time, the heating time is strictly controlled, and the total time from the start of heating to the coupling material reaching a fluid state does not exceed 30 minutes. During the heating period, the stirring function of the device must be continuously turned on, and the stirring speed is maintained at 80r / min to avoid local overheating and carbonization or bottom deposition of the coupling material, and to ensure that the formed fluid coupling material is uniform and consistent, without viscosity unevenness caused by local temperature differences. After the heating is completed, the temperature of the fluid coupling material is checked with a temperature detector. Only when the temperature is confirmed to be within the range of 180℃-200℃ can it proceed to the subsequent pouring stage. Step S4-3: First layered grouting of high-performance backfill coupling material: The initial layered filling operation is carried out using a specialized filling gun. High-performance backfill coupling material in a fluid state is introduced into the storage tank of the filling gun. The filling gun is moved at a uniform speed of 0.3 m / s along the length of the groove to ensure the fluid coupling material is evenly injected into the groove. During the filling process, the filling height of the coupling material in the groove must be observed in real time. The filling depth is controlled by the height monitoring device on the filling gun, ultimately achieving a depth of 2-3 cm for the first filling of fluid coupling material. After completing one section (single section length not exceeding 50 m), a small vibrator is immediately used to vibrate the fluid coupling material in the groove. The vibration frequency is set to 50 Hz, and the vibrator is stopped for 10 seconds every 10 cm along the length of the groove to ensure the removal of air bubbles inside the fluid coupling material, preventing air bubble residue from causing voids after subsequent curing. After vibration, the actual depth of the coupling material is measured with a steel ruler, and the deviation must be controlled within ±0.1 cm. If the depth is insufficient, additional filling is carried out to the specified range. Step S4-4: Preliminary curing and condition inspection of high-performance backfill coupling material: After the initial infusion, the fluidized coupling material enters the preliminary curing stage, with a curing time set at 2 hours. During this period, personnel or equipment should be prevented from touching the grooved area to avoid scratches or dents on the surface of the coupling material. After the preliminary curing, the surface condition of the coupling material is inspected, including three aspects: first, surface flatness, observing that there are no obvious protrusions or dents on the surface, and measuring with a flatness meter, with a deviation not exceeding 0.2cm; second, surface integrity, with no cracks, delamination, or holes left by air bubbles; and third, fit with the sensing optical cable, visually observing that there are no gaps between the coupling material and the outer sheath of the optical cable. If a surface dent depth exceeding 0.2cm or a hole is found, a small amount of fluidized coupling material should be used for local replenishment. After replenishment, the area should be left to stand for 30 minutes again to ensure that the replenished area is initially integrated with the original coupling material. Step S4-5: Secondary grouting and groove flushing of high-performance backfill coupling material: After the initial high-performance backfill coupling material has completed its preliminary curing and passed the condition inspection, a second injection operation is carried out. The high-performance backfill coupling material, heated to a fluid state, is again introduced into the injection gun and injected along the length of the groove. During the injection process, the height of the coupling material is observed in real time until the liquid level of the coupling material is flush with the groove opening, i.e., at the same level as the roadbed and pavement surface. After injection, a metal scraper is immediately used to evenly scrape the surface of the coupling material along the length of the groove opening at a speed of 0.2 m / s, ensuring that there is no excess coupling material residue on the surface after scraping and that it blends smoothly with the surrounding pavement. After scraping, the surface flatness is measured again with a flatness meter. The overall deviation must be controlled within ±0.1 cm. If there are any areas that are higher or lower than the pavement surface, a second adjustment with a scraper is required to meet the requirements. Step S4-6: Complete curing and strength monitoring of high-performance backfill coupling material: After the secondary grouting is completed, the process enters the full curing stage, which is set to last 24 hours. During the curing period, the ambient temperature of the construction area must be maintained between 15℃ and 30℃ to avoid slow curing due to low temperatures or cracking due to high temperatures. After full curing, the surface hardness of the high-performance backfill coupling material is tested using a hardness tester. One test point is selected every 100m along the length of the groove, and each test point is measured 3 times and the average value is taken. The hardness must reach the preset design value (e.g., 50MPa). At the same time, an adhesion tester is used to test the adhesion between the coupling material and the sidewall of the groove and the outer sheath of the sensor optical cable. The adhesion must be no less than 3MPa to ensure that there is no risk of detachment between the coupling material and the roadbed, pavement, and sensor optical cable. If the hardness or adhesion does not reach the design value, the cause must be analyzed (e.g., insufficient heating temperature or insufficient curing time), and corresponding measures must be taken (e.g., extending the curing time to 36 hours) and the test must be repeated until the requirements are met. Step S4-7: Full-line inspection and secondary filling of the backfill trench: After the high-performance backfill coupling material has fully cured and its strength monitored, a full-line inspection of the backfill tank is conducted. The inspection combines visual observation with ultrasonic testing: visual inspection checks the tank surface for any missing sections, coupling material shrinkage and settlement, or exposed optical cables; ultrasonic testing is performed every 50m along the length of the tank to detect any cavities within the coupling material. If any missing sections or settlement are found, timely refilling is required. If exposed optical cables are found, the nearby coupling material must be heated, and the optical cable repositioned at the bottom of the tank and cured. If an internal cavity volume exceeds 1cm³, the coupling material must be heated until it melts and fills the cavity before refilling. The heating temperature should not exceed 150℃.

[0024] In this embodiment, steps S3 and S4 also include a step S0. The function of step S0 is to monitor the deployment status of the sensing optical cable in real time using an optical time domain reflectometer based on the entire construction process of the sensing optical cable deployment in step S3 and the coupled backfilling in step S4, promptly identify signal anomalies in the optical cable (such as breakage or excessive loss), and eliminate potential hazards by suspending construction and carrying out repairs. This avoids distortion or failure of subsequent roadbed disaster monitoring data due to abnormal optical cable status, and provides full protection for the functional integrity of the sensing optical cable. The detailed steps are as follows: Step S0-1 Optical Time Domain Reflectometer Adjustment and Calibration: First, the optical time domain reflectometer (OTDR) is debugged and calibrated. The OTD is then taken out and connected to a dedicated test optical cable (of known length and in good condition). The core parameters are set as follows: test wavelength is selected as 1550nm (to match the transmission characteristics of the sensing optical cable); pulse width is adjusted to 10ns (to ensure the test resolution meets the requirements for optical cable status monitoring); and the test range is set to 2.5km (covering a 2km length of a single reel of sensing optical cable, with a margin of safety). The calibration program is started, and the OTD emits light pulses to the test optical cable, receives the reflected signals, and generates a test curve. The deviation between the reflection peak position in the curve and the known length of the test optical cable is compared. If the deviation exceeds 0.1km, the distance calibration coefficient of the device is adjusted until the deviation is less than 0.1km. After calibration, the parameter settings are saved. The OTD is then connected to the beginning of the sensing optical cable to be deployed using a dedicated connector, ensuring that the connection is secure and free of dust to avoid signal interference caused by poor contact. Step S0-2: Monitoring and recording of baseline curves: Before laying the optical cable in step S3, an initial monitoring baseline curve for the sensing optical cable is collected. The optical time-domain reflectometer is activated, and the device emits light pulses to the sensing optical cable, continuously collecting reflection signal data three times with a one-minute interval between each collection. The average of the three data points is used to generate the initial baseline curve. The baseline curve must clearly show the attenuation distribution of the sensing optical cable throughout its entire length, with no obvious abnormal reflection peaks (such as steep reflection peaks caused by breakage) and no local attenuation abrupt changes (attenuation abrupt changes must be less than 0.1 dB / km). The initial baseline curve is stored in the device's memory and simultaneously exported to the monitoring system of the accompanying computer to establish a baseline database for the sensing optical cable, serving as a reference standard for judging whether the signal is abnormal during subsequent construction. If the initial baseline curve is abnormal, the connection status of the first end of the sensing optical cable must be checked immediately or the sensing optical cable segment must be replaced, and the baseline curve must be collected again until it meets the requirements. Real-time monitoring and anomaly warning during optical cable deployment in steps S0-3 and S3: During the cable laying and adjustment process in the optical cable trough using the vehicle-mounted winch in step S3, the optical time domain reflectometer (OTDR) remains continuously running, automatically acquiring the real-time reflection curve of the sensing optical cable every 30 seconds and comparing it with the initial reference curve. During the comparison, two key indicators are monitored: first, the change in attenuation value throughout the entire process; the difference between the real-time attenuation value and the reference attenuation value must be less than 0.2 dB / km. If the difference exceeds 0.2 dB / km, it is determined to be an attenuation anomaly; second, the change in the position of the reflection peak. If a new reflection peak appears in the real-time curve (not at the optical cable joint), or the original reflection peak position shifts by more than 0.2 km, it is determined to be a reflection anomaly. When an attenuation anomaly or a reflection anomaly is detected, the OTD immediately triggers an audible and visual warning, and simultaneously marks the abnormal location on the screen (accurate to a range of 0.1 km), reminding on-site construction personnel to suspend the optical cable laying operation in step S3. Step S0-4: Troubleshooting and Repairing the Fiber Optic Cable Upon receiving an anomaly warning, construction personnel locate the problem along the laid-out sensing optical cables based on the anomaly location marked by the optical time domain reflectometer. If the anomaly is located in an existing section of the cable, the personnel check for damage to the outer sheath (such as scratches caused by friction with the sidewall of the groove), local bending (bending radius less than the minimum allowable bending radius of the cable), or excessive tension (internal structural damage caused by cable tension). If the anomaly is located in an unlaid section of the cable, the personnel check for tangles or knots in the cable reel, or damage to the outer sheath. After identifying the cause, targeted repair measures are taken: for minor damage to the outer sheath, a special optical cable repair patch is used to wrap the damaged area, and the patch is heated to 80°C to fuse with the sheath; for local bending, the cable position is slowly adjusted to restore a natural, relaxed state, ensuring the bending radius meets requirements; for cable breakage or severe damage, the damaged section is cut off, and an optical cable fusion splicer is used for splicing. After splicing, the local reflection curve of the section is re-acquired to ensure the attenuation value at the splice is less than 0.1dB. Real-time monitoring and status maintenance during the coupled backfilling process in steps S0-5 and S4: During step S4, the heating and pouring of the coupling material (first pouring and second pouring) and curing process, the optical time domain reflectometer continues to monitor in real time, with the monitoring frequency adjusted to collect the real-time curve once every 1 minute, focusing on the impact of the coupling material heating temperature and pouring pressure on the optical cable signal. During the pouring process, if the real-time curve shows a brief attenuation fluctuation (fluctuation range 0.1-0.2dB / km) and the fluctuation duration is less than 1 minute, it is determined to be a temporary interference caused by the flow of the coupling material, and there is no need to stop construction. If the fluctuation range exceeds 0.2dB / km or the duration exceeds 1 minute, an alarm is triggered, the pouring operation is suspended, and the optical cable is checked for displacement or pressure damage due to the impact of the coupling material. During the curing process, the stability of the optical cable signal is monitored. If the attenuation increases slowly (more than 0.05dB / km per hour), it is necessary to check whether the curing environment temperature is too high (above 30℃), and take timely measures such as shading and ventilation to control the temperature and avoid changes in optical cable performance due to high temperature. Step S0-6: Re-testing and construction restoration after anomaly repair: After the optical cable is repaired or construction interference is eliminated, the optical time domain reflectometer (OTDR) retest program is started, and five real-time reflection curves are continuously collected. The average value is taken to generate the post-repair curve. The post-repair curve is compared with the initial reference curve again. If the attenuation difference is less than 0.2 dB / km and there are no abnormal reflection peaks, the repair is deemed qualified, the audible and visual warning is lifted, and the construction personnel are allowed to resume the work in steps S3 or S4. If the post-repair curve is still abnormal, the cause of the problem needs to be investigated again, the repair plan needs to be adjusted (such as replacing the fusion splice, readjusting the optical cable position), and the retest is repeated until it is qualified. The process data of each repair and retest (abnormal location, repair measures, retest results) must be recorded in detail in the monitoring log to ensure that the entire construction process is traceable. Final testing and confirmation of the entire line after curing in steps S0-7 and S4: After the coupling material in step S4 has completely cured and secondary filling is completed, a full-line final test of the sensing optical cable is carried out. Using the same parameters as the initial reference curve, an optical time-domain reflectometer (OTDR) is used to collect the final reflection curve of the entire optical cable, which is then compared with the initial reference curve. Simultaneously, the changing trends of all real-time curves during construction are compared. The final test must meet three requirements: first, the attenuation difference throughout the entire length is less than 0.2 dB / km, with no localized areas exceeding the attenuation limit; second, there are no new reflection peaks, and the positions of reflection peaks at existing joints are not shifted; third, the overall shape of the curve is consistent with the initial reference curve, with no permanent signal damage caused by construction. After the final test is passed, a final test report is generated, including the initial reference curve, records of construction process anomalies, repair records, the final test curve, and comparison results. The report is archived in the project monitoring file as a basis for the quality of the sensing optical cable deployment. If the final test fails, the impact of the coupling backfilling process on the optical cable needs to be analyzed (such as pressure on the optical cable caused by the curing shrinkage of the coupling material), a specific treatment plan needs to be developed, and the final test needs to be repeated until it passes.

[0025] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for deploying optical cables for monitoring disasters in highway subgrades, characterized in that: Includes the following steps: S1. Monitoring route selection: Select a monitoring route along the direction of traffic on the highway, 40-50cm away from the roadside guardrail; S2. Precision grooving: Using road grooving equipment, grooves are cut along the selected monitoring line to form a groove with a width of 1cm and a depth of 3-4cm; after grooving, the groove is cleaned and dried to ensure that the groove is clean and dry. S3. Fiber optic cable laying: The sensing fiber optic cable is laid at the bottom of the groove in a tension-free state; S4. Coupling backfill: After heating the high-performance backfill coupling material to a fluid state, it is poured into the groove containing the sensing optical cable and then cured to allow the sensing optical cable to form a mechanical coupling with the roadbed and pavement structure through the high-performance backfill coupling material. The depth of the trench is adjusted according to the type of roadbed: 3cm for the excavation section and 4cm for the embankment section.

2. The method for laying optical cables for highway subgrade disaster monitoring according to claim 1, characterized in that: In steps S3 and S4, there is also a step S0: using an optical time domain reflectometer to monitor the deployment status of the sensing optical cable in real time; if an abnormal signal is detected, construction is suspended and the optical cable is repaired.

3. The method for laying optical cables for highway subgrade disaster monitoring according to claim 1, characterized in that: In step S1, after selecting the monitoring line, the existing pavement defects on the line are pretreated, including the repair of potholes, bumps and cracks.

4. The method for laying optical cables for monitoring disasters in highway subgrades according to claim 1, characterized in that: In step S2, the road grooving equipment is a modified milling machine. This modified milling machine is equipped with a grooving depth intelligent control module and a binocular vision-assisted driving module to ensure the accuracy of the grooving depth and the straightness of the line.

5. The method for laying optical cables for highway subgrade disaster monitoring according to claim 4, characterized in that: The modified milling machine is also equipped with a tool spray cooling device, which sprays water at a rate of 0.5 kg / m to cool the blades during the grooving process.

6. The method for laying optical cables for monitoring disasters in highway subgrades according to claim 1, characterized in that: In step S2, the drying process is as follows: when construction is carried out after rain or under humid conditions, a powdered desiccant is applied into the groove. The main components of the desiccant are silica gel or calcium chloride. The reaction time is no more than 10 minutes. After absorbing water, it becomes a free-flowing granular form that is easy to clean.

7. The method for laying optical cables for highway subgrade disaster monitoring according to claim 1, characterized in that: In step S3, a vehicle-mounted winch is used to lay the optical cable. The single-reel length of the sensing optical cable is 2km, and the optical cable is kept in a slack state during the laying process.

8. The method for laying optical cables for monitoring disasters in highway subgrades according to claim 1, characterized in that: In step S4, the heating temperature of the high-performance backfill coupling material does not exceed 200°C, and the heating time does not exceed 30 minutes.

9. The method for laying optical cables for highway subgrade disaster monitoring according to claim 1, characterized in that: In step S4, the grouting adopts a layered backfilling process: first, the fluid coupling material is poured into the groove to a depth of 2-3cm, and after it has initially solidified, the remaining part is poured until it is flush with the groove opening.

10. The method for laying optical cables for highway subgrade disaster monitoring according to claim 1, characterized in that: After the coupling material has completely solidified, a full inspection of the backfill tank is carried out, and local voids caused by solidification shrinkage are filled a second time.

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