A structure for monitoring the temperature field of frozen soil roadbed

Abstract

This utility model discloses a temperature field monitoring structure for frozen soil subgrade, overcoming the shortcomings of existing technologies that suffer from insufficient monitoring density or excessively high operating costs, making it difficult to monitor the end face temperature field of frozen soil subgrades. The structure includes a sensor array and a temperature monitoring module. The sensor array contains several temperature-measuring cables, which are layered along the transverse, longitudinal, and depth directions of the frozen soil subgrade to form temperature-measuring cable nodes, achieving full cross-section coverage of the subgrade and increasing monitoring density. The temperature monitoring module includes a temperature acquisition module and a data transmission module. The temperature acquisition module connects to the temperature-measuring cable nodes to collect temperature signals, and the data transmission module connects to the temperature acquisition module to upload signals. Its structure is simple, requires no high-cost components, reduces operating costs, and provides support for accurate monitoring of the temperature field of frozen soil subgrades.

Description

Technical Field

[0001] This utility model relates to the field of frozen soil engineering monitoring technology, specifically to a frozen soil subgrade temperature field monitoring structure. Background Technology

[0002] Permafrost refers to rock and soil masses whose temperature remains below 0℃ for extended periods and contain ice. Its physical and mechanical properties exhibit significant temperature sensitivity, posing multiple threats to engineering construction in cold regions: on the one hand, the frost heave and thaw settlement caused by the ice-to-water phase transition directly lead to uneven deformation of the roadbed; on the other hand, the long-term rheological properties of permafrost further exacerbate the risk of structural instability, especially under thermal disturbances, which can easily form irreversible thaw cycles, resulting in continuous accumulation of settlement during long-term service. Therefore, real-time monitoring of temperature field changes in permafrost roadbeds is crucial.

[0003] However, the significant limitations of current monitoring technologies are mainly reflected in insufficient monitoring density and excessively high operating costs, which directly lead to numerous difficulties in monitoring the temperature field of permafrost roadbed sections. Specifically, single-point temperature measuring cables, limited by their inherent characteristics, suffer from severely insufficient spatial resolution, making it difficult to comprehensively capture temperature changes in different areas of the roadbed and easily creating data blind spots. While high-cost fiber optic grating systems can improve monitoring density to some extent, they face technical bottlenecks such as fragile optical paths, excessive power consumption, and difficult maintenance, resulting in high operating costs and hindering long-term large-scale application. Both of these methods fail to achieve full-area perception of the roadbed cross-section temperature field and also pose a risk of response lag, posing potential safety hazards to projects in cold regions.

[0004] Therefore, there is an urgent need for a technical solution that can continuously monitor the temperature field of the entire cross section of frozen soil roadbed while ensuring low-cost operation, so as to provide technical support for the safety of engineering in cold regions. Utility Model Content

[0005] The purpose of this utility model is to provide a temperature field monitoring structure for frozen soil subgrade, so as to overcome the shortcomings of the existing technology, which makes it difficult to monitor the temperature field at the end face of frozen soil subgrade due to insufficient monitoring density or high operating costs.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A structure for monitoring the temperature field of frozen soil subgrade includes: The sensor array includes several temperature measuring cables, which are laid out in layers along the transverse, longitudinal and depth directions of the frozen soil subgrade to form temperature measuring cable nodes. The temperature monitoring module includes a temperature acquisition module and a data transmission module; the temperature acquisition module is connected to the temperature measuring cable node and is used for temperature signal acquisition. The data transmission module connects to the temperature acquisition module and uploads the temperature signal.

[0007] The temperature measuring cable is an armored temperature measuring cable, with an insulating protective sleeve and a metal protective sleeve arranged sequentially on the outside of the cable.

[0008] The temperature acquisition module is also connected to a signal processing module, which includes a signal conditioning circuit and an edge computing gateway, to receive and process temperature signals.

[0009] It also includes a hybrid energy storage unit, which is used to provide power to the temperature monitoring module.

[0010] The hybrid energy storage unit consists of a solar power unit, a supercapacitor, and a low-temperature lithium battery connected in parallel.

[0011] The solar power unit uses monocrystalline silicon photovoltaic panels and integrates a carbon fiber heating film.

[0012] It also includes a power management module, which is connected to the hybrid energy storage unit. The power management module adjusts the working mode of the hybrid energy storage unit, temperature monitoring module and data transmission module according to the status of the hybrid energy storage unit.

[0013] The temperature acquisition module also integrates a data compression unit and a redundant storage unit.

[0014] The data transmission module uses LoRa self-organizing network units and supports multi-hop relay transmission.

[0015] The temperature acquisition module also integrates a data compression unit and a redundant storage unit. The data compression unit is used to reduce the amount of data, and the redundant storage unit is used to provide additional backup storage space.

[0016] Compared with the prior art, the present invention has the following beneficial technical effects: This invention proposes a temperature field monitoring structure for frozen soil subgrade. To improve monitoring density and eliminate blind spots, the sensor array employs a multi-dimensional, layered layout. Instead of traditional single-point or localized deployment, the temperature measuring cables are laid in layers along the transverse, longitudinal, and depth directions of the frozen soil subgrade, forming cable nodes. This layout covers the key transverse areas, the longitudinal extension range, and the natural foundation area in the depth direction of the frozen soil subgrade, constructing a monitoring network covering the entire subgrade cross-section. This allows for comprehensive capture of temperature signals from different locations within the subgrade, effectively solving the problems of insufficient spatial resolution and data blind spots inherent in traditional single-point monitoring technologies. It provides structural support for accurately acquiring the temperature field distribution of the frozen soil subgrade cross-section.

[0017] In terms of reducing operating costs and improving economic efficiency, this utility model achieves core monitoring functions through a streamlined and efficient modular architecture. The sensor array consists of temperature-measuring cables, eliminating the need for high-cost dedicated monitoring components. Each module focuses on the acquisition and uploading of temperature signals, with direct interconnections between modules. This significantly reduces the procurement expenditure of high-cost equipment, simplifies system maintenance processes, and lowers equipment wear and tear and operating costs during long-term operation. It effectively avoids the problem of excessively high operating costs caused by reliance on high-cost equipment or complex structures in existing technologies, thus improving the economic efficiency and practicality of the technical solution. This makes it more suitable for long-term application in monitoring permafrost subgrades in cold regions. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a frozen soil roadbed temperature field monitoring structure in an embodiment of this utility model.

[0019] Figure 2 This is a schematic diagram of the layout of the roadbed cross-section sensor array in a frozen soil roadbed temperature field monitoring structure according to an embodiment of this utility model.

[0020] Figure 3 This is a schematic diagram of a temperature monitoring module in a frozen soil roadbed temperature field monitoring structure according to an embodiment of this utility model.

[0021] In the diagram, 1. Sensor array; 2. Temperature monitoring module; 3. Frozen soil subgrade; 4. Stone layer; 5. Subgrade fill layer; 6. Pavement structure layer; 7. Temperature measuring cable; 8. Temperature measuring cable node; 9. Data transmission bus; 10. Temperature acquisition module; 11. Data transmission module; 12. Power consumption management module; 13. Hybrid energy storage unit; 14. Concrete foundation. Detailed Implementation

[0022] During engineering construction in cold regions, the physical and mechanical properties of permafrost pose a threat to roadbeds, making real-time monitoring of temperature field changes in permafrost roadbeds crucial. Current monitoring technologies, such as single-point temperature measurement cables, lack sufficient spatial resolution, making it difficult to comprehensively capture temperature changes in different areas of the roadbed and easily creating data blind spots. While fiber optic grating systems can improve monitoring density to some extent, their high operating costs hinder long-term, large-scale application. Both methods fail to achieve comprehensive sensing of the roadbed cross-section temperature field and pose a risk of response lag, posing potential safety hazards to engineering projects in cold regions.

[0023] Therefore, there is an urgent need for a technical solution that can continuously monitor the temperature field of the entire cross section of frozen soil roadbed while ensuring low-cost operation, so as to provide technical support for the safety of engineering in cold regions.

[0024] Based on the above background, this utility model proposes a temperature field monitoring structure for frozen soil subgrade. It takes a three-dimensional sensor array as the core and forms a multi-node monitoring network by layering temperature measuring cables along the transverse, longitudinal and depth sides of the subgrade. This network covers key areas of the subgrade and makes up for the insufficient density of single-point monitoring in the existing technology. At the same time, each module works together to collect and upload temperature signals without the need for high-cost and complex equipment, thus reducing operating costs and overcoming monitoring difficulties.

[0025] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0026] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0027] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installed," "equipped with," "sleeved / connected," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0028] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "several" means two or more, unless otherwise explicitly specified.

[0029] Reference Figure 1 The image shows a specific embodiment of the frozen soil subgrade temperature field monitoring structure provided by this utility model, comprising: The sensor array 1 includes several temperature measuring cables 7, which are laid out in layers along the transverse, longitudinal and depth directions of the frozen soil subgrade to form temperature measuring cable nodes 8. Temperature monitoring module 2 includes temperature acquisition module 10 and data transmission module 11; temperature acquisition module 10 is connected to temperature measuring cable node 8 and is used for temperature signal acquisition. The data transmission module 11 is connected to the temperature acquisition module 10 and uploads the temperature signal.

[0030] The sensor array 1 consists of several temperature-measuring cables 7. These cables are laid out in layers along the transverse, longitudinal, and depth directions of the frozen soil subgrade, forming temperature-measuring cable nodes 8. The transverse layering covers key transverse areas of the frozen soil subgrade, such as the subgrade center and left and right shoulders; the longitudinal layering extends throughout the longitudinal extent of the frozen soil subgrade; and the depth layering reaches the natural foundation beneath the frozen soil subgrade, covering soil layers at different depths. This three-dimensional layered layout allows the temperature-measuring cable nodes 8 to form a monitoring network covering the entire cross-section of the frozen soil subgrade, avoiding the incomplete monitoring range problems caused by traditional single-direction or partial layouts, and ensuring that temperature conditions at different locations along the frozen soil subgrade can be captured.

[0031] Temperature monitoring module 2 is connected to sensor array 1 to collect, process and transmit temperature data. Temperature monitoring module 2 includes temperature acquisition module 10 and data transmission module 11.

[0032] The temperature acquisition module 10 is connected to the temperature measuring cable node 8 and its function is to acquire temperature signals. After the temperature measuring cable node 8 obtains the temperature at various locations in the frozen soil subgrade, it transmits the raw temperature signals to the temperature acquisition module 10. The temperature acquisition module 10, through its signal receiving and processing functions, converts the raw signals into temperature signals that can be subsequently transmitted. The temperature acquisition module 10 is a crucial intermediate link in the transmission of temperature information, ensuring that the temperature information of the frozen soil subgrade can be effectively collected, providing a foundation for subsequent data uploading.

[0033] The data transmission module 11 is connected to the temperature acquisition module 10 and uploads the temperature signals collected by the temperature acquisition module 10. Through the upload function of the data transmission module 11, the temperature signals of the frozen soil subgrade can be transmitted to the backend monitoring platform or storage device, allowing staff to obtain the temperature data of the frozen soil subgrade in a timely manner, realizing remote monitoring of the temperature field of the frozen soil subgrade, and providing data support for subsequent analysis of the temperature changes of the frozen soil subgrade and assessment of the subgrade safety status.

[0034] In another specific embodiment of this utility model, the temperature measuring cable 7 in the frozen soil subgrade temperature field monitoring structure is an armored temperature measuring cable. An insulating protective sleeve and a metal protective sleeve are sequentially arranged on the outside of the cable. In this specific embodiment, the armored temperature measuring cable node 8 uses a 25 mm diameter stainless steel corrugated sheath, internally encapsulating a PT1000 platinum resistance sensor. The node is sealed with high-density silicone and connected to the data transmission bus 9 via an M16 waterproof plug, supporting rapid on-site replacement and enhancing resistance to frost heave, compression, and pull-out. (Refer to...) Figure 2 As shown, armored temperature measuring cables are installed in the subgrade fill layer 5, rubble layer 4, and frozen soil foundation 3 of the frozen soil subgrade below the road structure layer 6. They are laid out in layers along the transverse, longitudinal, and depth directions of the frozen soil subgrade, and the temperature measuring cable nodes 8 form a distributed temperature sensor array 1. The transverse cables are buried in layers along the center of the frozen soil subgrade cross-section, the left and right shoulders, and the left and right slope toes, covering the entire cross-section of the frozen soil subgrade. The depths are vertically buried according to the frozen soil subgrade, with depths of 0.5 meters, 1.5 meters, 2.5 meters, and 3.5 meters, with a vertical spacing of 1 meter, reaching a maximum depth of 11.5 meters. The positioning accuracy is as high as ±0.1 meters, which can accurately capture the freeze-thaw interface and the expansion trend of the thawing zone.

[0035] The temperature acquisition module 10 is also connected to a signal processing module to jointly realize the acquisition, processing, and early warning of temperature signals. The temperature acquisition module 10 is connected to the sensor array 1 via the data transmission bus 9. The temperature acquisition module 10 is also connected to the signal processing module, which includes a signal conditioning circuit and an edge computing gateway, to receive and process temperature signals. The signal conditioning circuit integrates an AD8421 instrumentation amplifier and an ADS1248 24-bit ADC. The AD8421 instrumentation amplifier has a gain of 100 times and an input bias current of less than or equal to 50 picoamps. The ADS1248 24-bit ADC has an effective resolution of 21.5 bits and a sampling rate of 10 SPS, supporting multi-channel synchronous acquisition and improving the accuracy of temperature signal acquisition. The edge computing gateway is based on an STM32H7 microcontroller with a main frequency of 480 MHz. The STM32H7 microcontroller is equipped with a floating-point unit (FPU) and uses a Kalman filter algorithm to eliminate environmental interference in real time. The noise covariance Q of the Kalman filter algorithm is 0.01 degrees Celsius, and the observation noise covariance R is 0.05 degrees Celsius. In another specific embodiment of this invention, the STM32H7 microcontroller can also achieve temperature trend prediction using an LSTM prediction model. The LSTM prediction model has 12 nodes in the input layer corresponding to the temperature sequence of the past 12 hours, 16 nodes in the hidden layer, and 1 node in the output layer. The training error MAE of the LSTM prediction model is less than or equal to 0.3 degrees Celsius. Thirdly, it provides anomaly warnings. When the deviation between the real-time temperature and the predicted value exceeds 1.5 degrees Celsius, a three-level warning system (yellow, orange, and red) is triggered, and the alarm code is pushed in real time through the data transmission module 11. In this specific embodiment, the data transmission module 11 uses a LoRa self-organizing network unit.

[0036] The temperature acquisition module 10 also integrates a data compression unit and a redundant storage unit. The redundant storage unit uses a Samsung KLMAG1JETD 8GB eMMC, which has a write cycle life of 100,000 cycles and retains the most recent 30 days of data according to a cyclic overwrite strategy. The data compression unit is used to reduce the amount of data, and the redundant storage unit is used to provide additional backup storage space to ensure data reliability and integrity.

[0037] The monitoring structure provided in this specific embodiment also includes a hybrid energy storage unit 13, which connects to the temperature acquisition module 10, the data transmission module 11, and the signal processing module, providing stable power to each module. The hybrid energy storage unit 13 consists of a solar power supply unit, a supercapacitor, and a low-temperature lithium battery connected in parallel. The solar power supply unit uses a monocrystalline silicon photovoltaic panel, model Trina TSM-410, with a peak power of 150 watts and a conversion efficiency of 22.3%. It is installed using an adjustable tilt bracket, with the tilt angle calculated based on the local latitude plus 15 degrees. An HW-826 carbon fiber heating film is integrated on the back of the monocrystalline silicon photovoltaic panel. The HW-826 carbon fiber heating film has a power density of 5 watts per square meter, and its size matches the monocrystalline silicon photovoltaic panel. When the ambient temperature is less than or equal to -5 degrees Celsius and the snow depth is greater than or equal to 3 centimeters, intelligent snow removal is automatically activated, with a daily operating time of less than or equal to 2 hours, ensuring stable power supply in extremely cold environments.

[0038] The supercapacitor and low-temperature lithium battery are equipped with a BMS management system, supporting wide temperature range from -40 degrees Celsius to 60 degrees Celsius. They can achieve 90 days of continuous self-powered operation in winter, providing energy guarantee for the long-term stable operation of the monitoring structure.

[0039] The data transmission module 11 is connected to the temperature acquisition module 10 via the data transmission bus 9, and is used to upload the processed temperature signal. In this specific embodiment, the data transmission module 11 adopts a LoRa self-organizing network unit. The LoRa self-organizing network unit node has a built-in SX1276 chip. The SX1276 chip has a transmit power of 20 dBmW and a receive sensitivity of -148 dBmW. It uses the 470 MHz frequency band, supports multi-hop relay transmission, has a maximum relay level of 5 hops, a relay spacing of 500 meters, a maximum communication distance of 1.5 kilometers, and a packet loss rate of less than 0.5%. The transmission strategy utilizes a 4G / 5G dual-mode gateway employing the Quectel RM500Q module. The Quectel RM500Q module supports the 5G NSAN78 band and the 4G TDD-LTE B41 band, prioritizing the 5G network. When the RSRP is greater than or equal to -90 dBmW, the 5G network is activated, with a theoretical uplink speed of 300 Mbps. When the signal strength is less than -90 dBmW, it automatically switches to the 4G network, with a bandwidth of 20 MHz and an uplink speed of 100 Mbps. In the event of a network interruption, the monitoring structure caches the data to 8GBeMMC and attempts to retransmit every 2 hours. The threshold for resuming transmission after a breakpoint is 512 kilobytes, effectively reducing the risk of data loss and ensuring data integrity and transmission reliability.

[0040] The monitoring structure provided in this specific embodiment also includes a power management module 12, which has a built-in dynamic power controller. The power management module 12 is connected to the hybrid energy storage unit 13 and adjusts the working mode of the monitoring structure according to the state of the hybrid energy storage unit 13. Specific modes include normal mode, energy-saving mode, and emergency mode, and the specific triggering conditions for each mode are as follows: The normal mode is triggered when the battery level is greater than 70%, the data acquisition interval is 1 hour, and the data transmission module 11 maintains real-time transmission. The power saving mode is triggered when the battery level is between 30% and 70%, the data collection interval is extended to 4 hours, and the data transmission module 11 is only activated for transmission between 12:00 and 14:00 every day. The emergency mode is triggered when the battery level is less than 30%, the data acquisition interval is extended to 8 hours, and the data transmission module 11 retains only the transmission function of the LoRa self-organizing unit to ensure critical data transmission.

[0041] When specifically deploying the frozen soil subgrade temperature field monitoring structure provided by this utility model, the temperature detection module can be set on the concrete foundation 14. The concrete foundation 14 is made of C35 concrete and has dimensions of 700×350×200mm. M8 anchor bolts are pre-embedded, with a length of 150mm and an anti-freezing pull-out torque greater than or equal to 80kN·m.

[0042] Maintenance operations after the monitoring structure is deployed can be performed only once a year in July. This includes calibrating the temperature sensing cable 7 and replacing the aging lithium batteries in the hybrid energy storage module. Calibration of the temperature sensing cable 7 specifically involves calibrating the PT1000 platinum resistance sensor built into the temperature sensing cable node 8 using a Fluke 754 process calibrator. The PT1000 platinum resistance sensor is replaced when its error exceeds 0.3 degrees Celsius. The lithium battery is forcibly replaced when its capacity decays to below 70% of its nominal value. This reduces the monitoring structure's maintenance frequency to once a year, lowers manual inspection costs, and enables unattended operation.

[0043] Temperature acquisition module 10 acquires temperature signals through temperature measurement cable node 8, and transmits the data to data transmission module 11 via signal processing module; power management module 12 dynamically switches working modes to match appropriate energy supply strategies for each module, ensuring stable operation of the monitoring structure in extremely cold environments.

[0044] Compared with existing technologies, this monitoring structure achieves full-section monitoring with a positioning accuracy of ±0.1 meters through the three-dimensional deployment of a distributed temperature sensor array; the hybrid energy storage and intelligent power consumption design enables 90 days of self-powered operation in winter; dual-mode redundant communication ensures no data loss; and low maintenance frequency reduces costs, ultimately providing efficient and reliable technical support for the safety of cold region engineering projects.

[0045] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed utility model. The scope of protection of this utility model is defined by the appended claims and their equivalents.

Claims

1. A structure for monitoring the temperature field of frozen soil roadbed, characterized in that, include: The sensor array (1) includes several temperature measuring cables (7), which are laid out in layers along the transverse, longitudinal and depth directions of the frozen soil subgrade to form temperature measuring cable nodes (8); The temperature monitoring module (2) includes a temperature acquisition module (10) and a data transmission module (11); the temperature acquisition module (10) is connected to the temperature measuring cable node (8) for temperature signal acquisition; the data transmission module (11) is connected to the temperature acquisition module (10) for uploading the temperature signal. The temperature measuring cable (7) is an armored temperature measuring cable, with an insulating protective sleeve and a metal protective sleeve arranged sequentially on the outside of the cable; the armored temperature measuring cable is installed in the roadbed fill layer (5), the rubble layer (4) and the frozen soil foundation below the road structure layer (6), and is buried in layers along the center of the frozen soil roadbed section, the left and right shoulders and the left and right slope toes; The temperature acquisition module (10) is also connected to a signal processing module, which includes a signal conditioning circuit and an edge computing gateway. The signal processing module receives and processes the temperature signal. The signal conditioning circuit integrates an AD8421 instrumentation amplifier and an ADS1248 24-bit ADC. The edge computing gateway is based on an STM32H7 microcontroller. It also includes a hybrid energy storage unit (13) and a power management module (12). The hybrid energy storage unit (13) is used to provide power to the temperature monitoring module (2). The hybrid energy storage unit (13) is composed of a solar power supply unit, a supercapacitor and a low-temperature lithium battery connected in parallel. The solar power supply unit adopts a monocrystalline silicon photovoltaic panel and integrates a carbon fiber heating film. The power management module (12) is connected to the hybrid energy storage unit (13), and the power management module (12) adjusts the working mode of the hybrid energy storage unit (13), the temperature monitoring module (2) and the data transmission module (11) according to the status of the hybrid energy storage unit (13); The data transmission module (11) adopts LoRa self-organizing network unit and supports multi-hop relay transmission.

2. The structure for monitoring the temperature field of frozen soil roadbed according to claim 1, characterized in that, The temperature acquisition module (10) also integrates a data compression unit and a redundant storage unit.

3. The structure for monitoring the temperature field of frozen soil roadbed according to claim 1, characterized in that, The temperature acquisition module (10) also integrates a data compression unit and a redundant storage unit. The data compression unit is used to reduce the amount of data, and the redundant storage unit is used to provide additional backup storage space.

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