Asphalt pavement distributed optical fiber permanent deformation monitoring method under moving load

Abstract

The invention belongs to the technical field of pavement monitoring methods, and particularly discloses a distributed optical fiber permanent deformation monitoring method for an asphalt pavement under a moving load. The method comprises the following steps: laying a single-mode optical fiber in a test piece; laying a full-bridge strain gauge in the test piece; monitoring an optical fiber vibration signal of the test piece during the movement of a test wheel and a strain change of the test piece during the movement of the test wheel in real time through a strain acquisition instrument; processing the optical fiber vibration signal and the strain change by using matlab data analysis software; analyzing the data change trend according to the processed optical fiber vibration signal and the strain change, and establishing a mathematical relationship between the two; and according to the mathematical relationship, distributed monitoring of the permanent deformation of the asphalt pavement under the moving load by the optical fiber vibration signals is realized. By the adoption of the bituminous pavement distributed optical fiber permanent deformation monitoring method under the moving load, real-time, dynamic, large-range, long-distance and high-precision monitoring of bituminous pavement permanent deformation is achieved, and the defects in the prior art are overcome.

Description

Technical Field

[0001] The present invention relates to the technical field of pavement monitoring methods, and in particular to a distributed optical fiber permanent deformation monitoring method for asphalt pavement under moving load. Background Art

[0002] With rapid economic development, the continuous expansion of transportation infrastructure construction, and the ever-increasing size of road networks, pavement deformation monitoring has become a crucial issue for improving road safety and traffic efficiency. While current pavement deformation monitoring methods, such as point sensors, infrared technology, radar detection, and digital imaging, are widely used in engineering practice, they have significant limitations, particularly for monitoring pavement over large areas and long distances.

[0003] Current monitoring methods have the following main shortcomings:

[0004] Local limitations: Current monitoring methods can only obtain information from a limited number of monitoring points, making it difficult to achieve comprehensive monitoring of permanent deformation of a large area of ​​road surface, resulting in local information being unable to represent the overall road surface condition.

[0005] Lack of real-time performance: Some monitoring technologies, such as infrared technology and digital imaging, require post-data processing and cannot achieve real-time monitoring and dynamic evaluation, which limits their application in complex traffic conditions.

[0006] Limited monitoring accuracy: Technologies such as radar detection are greatly affected by environmental factors, such as signal interference and temperature changes, which may lead to reduced monitoring accuracy, especially for the detection of small deformations.

[0007] High equipment costs and complex maintenance: Some monitoring technologies, such as point sensor systems, require a large number of sensors and supporting equipment, which have high installation and maintenance costs and are easily damaged in harsh environments, making them unfavorable for long-term stable operation. Summary of the Invention

[0008] The purpose of the present invention is to provide a distributed optical fiber permanent deformation monitoring method for asphalt pavement under moving load, so as to realize real-time, dynamic, large-scale, long-distance and high-precision monitoring of permanent deformation of asphalt pavement and overcome the shortcomings of the existing technology.

[0009] To achieve the above objectives, the present invention provides a method for monitoring the permanent deformation of asphalt pavement under moving loads using distributed optical fiber, comprising the following steps:

[0010] Step 1: Establish a distributed optical fiber deformation monitoring system and lay a single-mode optical fiber in a double-layer asphalt mixture rutting specimen: the double-layer asphalt mixture rutting specimen includes a first layer rutting board and a second layer rutting board;

[0011] Step 2: Build a strain monitoring system and install full-bridge strain gauges in the double-layer asphalt mixture rutting specimen:

[0012] Step 3: Data acquisition: using a strain gauge to monitor in real time the optical fiber vibration signal and strain changes of the double-layer asphalt mixture rutting specimen during the standard rutting test when the test wheel moves;

[0013] Step 4: Data processing: using Matlab data analysis software to process the optical fiber vibration signal and strain change in step 3;

[0014] Step 5: Establishing a mathematical relationship: Analyze the data change trend of the optical fiber vibration signal and strain change processed in step 4, and establish a mathematical relationship between the two based on the data change trend;

[0015] Step 6: Establishing the evaluation model: Based on the mathematical relationship in step 5, the distributed monitoring of the permanent deformation of the asphalt pavement under the moving load by the optical fiber vibration signal is realized.

[0016] Preferably, in step 1, a single-mode optical fiber laying route perpendicular to the test wheel movement direction is set in the laying area on the upper surface of the double-layer asphalt mixture rutting specimen, an optical fiber groove is engraved along the optical fiber laying route, a single-mode optical fiber is laid straight in the groove, and epoxy resin is filled in the optical fiber groove to form a protective shell after the epoxy resin is cured.

[0017] Preferably, in step 2, the laying position of the full-bridge strain gauge is set on the upper surface of the lower layer of the double-layer asphalt mixture rutting specimen, a groove matching the size of the full-bridge strain gauge is prepared at the laying position, a fine sand layer and asphalt are laid on the lower part of the groove, the full-bridge strain gauge is embedded in the groove, a fine sand layer and asphalt are laid on the upper part of the full-bridge strain gauge to form a protective layer, and then the second layer of rutting plate is synthesized.

[0018] Preferably, in step 3, the strain collector is connected to the single-mode optical fiber to ensure stable signal transmission, and the acquisition frequency is adjusted according to the test wheel movement speed and the test piece characteristics to capture the complete vibration signal. During the standard rutting test, the vibration signal generated when the test wheel moves is transmitted to the optical fiber, and the strain collector records these signals in real time; the full-bridge strain gauge is connected to the strain collector to ensure that the strain data collected by the full-bridge strain gauge can be transmitted to the strain collector in real time. During the movement of the test wheel, the strain collector monitors the strain changes of the test piece in real time and records the stress response feedback from the full-bridge strain gauge.

[0019] Preferably, in step 4, the optical fiber vibration signal is converted from the time domain to the frequency domain by Fourier transform, and the frequency domain feature data is extracted.

[0020] Preferably, in step 4, the singular values ​​and abnormal points in the strain change data of step 3 are eliminated using MATLAB data analysis software.

[0021] The advantages and beneficial effects of the present invention using the above-mentioned distributed optical fiber permanent deformation monitoring method for asphalt pavement under moving load are:

[0022] 1. Continuous Distributed Monitoring: This invention uses distributed fiber optic technology to continuously monitor the entire fiber line, rather than being limited to a single monitoring point. It can obtain strain and displacement data across the entire monitoring area, enabling a more accurate assessment of the road's overall permanent deformation.

[0023] 2. Real-time data acquisition: Distributed acoustic sensing (DAS) and dynamic strain acquisition technologies are used to achieve real-time data collection and transmission. By quickly acquiring vibration signals and strain data, timely and reliable basic data is provided for dynamic assessment of road deformation.

[0024] 3. Efficient monitoring at low cost: Fiber optic materials are corrosion-resistant and age-resistant, resulting in a long service life and requiring less frequent maintenance than traditional electrical sensors. This significantly reduces the maintenance cost of long-term monitoring and is particularly suitable for road monitoring projects requiring long-term, stable operation.

[0025] 4. Accurate monitoring results: The present invention can accurately detect tiny strain and displacement changes in the road surface with high sensitivity. It can be used to detect road deformation or damage at an early stage and provide timely warnings, thereby avoiding greater road safety hazards.

[0026] 5. Strong anti-interference ability: The optical fiber monitoring system has strong anti-electromagnetic interference ability and is not affected by external environmental factors (such as lightning, corrosion, high temperature, etc.). Therefore, even in harsh climate and traffic conditions, the monitoring system can still maintain stable and reliable operation.

[0027] 6. Strong range monitoring capability: Distributed fiber optic technology enables comprehensive monitoring of large-scale and long-distance road surfaces, overcoming the limitations of traditional point sensors and providing a holistic road health assessment.

[0028] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Schematic diagram of the layout of the distributed optical fiber deformation monitoring system of the present invention;

[0030] Figure 2 It is a schematic diagram of the layout of the strain monitoring system of the present invention.

[0031] Reference numerals

[0032] 1. Optical fiber; 2. Double-layer asphalt mixture rutting specimen; 3. First layer rutting plate; 4. Second layer rutting plate; 5. Full-bridge strain gauge. DETAILED DESCRIPTION

[0033] The technical solution of the present invention is further described below with reference to the accompanying drawings and embodiments.

[0034] Unless otherwise defined, the technical or scientific terms used in the present invention shall have the usual meanings understood by persons of ordinary skill in the field to which the present invention belongs. The words "first", "second" and similar terms used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Words such as "include" or "comprise" mean that the elements or objects preceding the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connect" or "connected" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0035] Example 1

[0036] A method for monitoring permanent deformation of an asphalt pavement under a moving load using a distributed optical fiber 1 includes the following steps:

[0037] Step 1: Establish a distributed optical fiber 1 deformation monitoring system:

[0038] Step 1.1, laying a single-mode optical fiber 1 in a double-layer asphalt mixture rutting specimen 2: the double-layer asphalt mixture rutting specimen 2 includes a first layer rutting plate 3, a second layer rutting plate 4 (such as Figure 1 shown);

[0039] Step 1.1.1: Mark the position of the fiber 1 laying line on the upper surface of the double-layer asphalt mixture rutting specimen 2, ensuring that it is located in the middle of the single-mode fiber 1 laying area and perpendicular to the direction of test wheel movement to effectively capture the vibration signal under the action of the test wheel;

[0040] Step 1.1.2: Create a groove for the fiber 1 along the planned fiber 1 laying route in the asphalt mixture surface. The width and depth of the groove must be precisely controlled based on the diameter of the single-mode fiber 1 to ensure a tight fit without affecting the stability of the optical signal. The single-mode fiber 1 is then laid straight in the groove.

[0041] In step 1.1.3, epoxy resin is injected into the groove of optical fiber 1 to completely cover the single-mode optical fiber 1. An epoxy resin with high adhesion, durability and crack resistance is selected to provide long-term and effective protection, and a solid protective shell is formed after natural curing to effectively prevent damage to optical fiber 1 from the external environment.

[0042] Step 2: Build a strain monitoring system:

[0043] Step 2.1: Lay a full-bridge strain sensor in the double-layer asphalt mixture rutting specimen 2:

[0044] Step 2.1.1, set the laying position of the full-bridge strain gauge 5 in the middle position of the upper surface of the lower layer of the specimen to ensure that it is located in the stress concentration area, so as to obtain accurate strain data according to the structure of the lower layer of the double-layer asphalt mixture rutting specimen 2 (such as Figure 2 shown);

[0045] Step 2.1.2: Make a groove at the selected placement location that exactly matches the size of the strain gauge. Ensure that its depth and width allow the strain gauge to be flush with the specimen surface after embedding, without affecting the overall mechanical properties of the specimen.

[0046] Step 2.1.3: First, lay a layer of fine sand and asphalt material at the bottom of the groove, and then embed the full-bridge strain gauge 5 therein to reduce the direct impact of external stress on the strain gauge and protect its sensitive components;

[0047] In step 2.1.4, a layer of fine sand and asphalt material is laid on the strain gauge to form a protective layer, ensuring that it completely covers the strain gauge and is tightly bonded to the surrounding asphalt material. Finally, a second layer of asphalt mixture rutting plate is synthesized to restore the integrity of the specimen.

[0048] Step 3, data collection:

[0049] Step 3.1: Use the DAS data acquisition device to monitor the vibration signal of optical fiber 1 in real time. Connect single-mode optical fiber 1 to the DAS data acquisition device to ensure stable signal transmission. Adjust the acquisition frequency based on the test wheel movement speed and test specimen characteristics to capture the complete vibration signal. During the standard rutting test, the vibration signal generated by the test wheel movement is transmitted to optical fiber 1, and the DAS data acquisition device records these signals in real time.

[0050] In step 3.2, the full-bridge strain gauge 5 is connected to the dynamic strain collector to ensure that the strain data collected by the strain gauge can be transmitted to the collector in real time. During the movement of the test wheel, the dynamic strain collector monitors the strain changes of the test piece in real time and records the stress response fed back by the strain gauge.

[0051] Step 4, data processing:

[0052] Step 4.1.1: Use Matlab data analysis software to denoise the optical fiber 1 vibration signal collected in step 3.1 to eliminate environmental interference and measurement noise;

[0053] Step 4.1.2: Convert the denoised signal to the frequency domain by Fourier transform, and extract the frequency domain feature data.

[0054] In step 4.2, the strain data collected in step 3.2 were analyzed using MATLAB data analysis software to remove singular values ​​and outliers to ensure the accuracy of the data.

[0055] Step 5, mathematical relationship establishment:

[0056] Step 5.1, perform trend analysis on the frequency domain characteristics of the vibration signal of optical fiber 1 to extract characteristic variables related to permanent deformation of the road surface;

[0057] Step 5.2: Determine the strain characteristics of the pavement under load based on the changing trend of the strain data;

[0058] Step 5.3: Establish a mathematical relationship between the data in steps 5.1 and 5.2 based on their changing trends.

[0059] Step 6: Evaluation model establishment:

[0060] Step 6.1, quantifying the permanent deformation of the road surface based on the mathematical relationship established in step 5 and combining the characteristics of the frequency domain signal of optical fiber 1;

[0061] In step 6.2, based on the distribution characteristics of the vibration signal of optical fiber 1, distributed dynamic monitoring of the permanent deformation of the asphalt pavement under the action of moving load is realized, covering the entire surface of the specimen to achieve large-scale, high-precision deformation assessment, and displaying the monitoring results through visualization tools or data reports.

[0062] Therefore, the present invention utilizes the aforementioned distributed fiber-optic permanent deformation monitoring method for asphalt pavement under moving loads. This method utilizes distributed fiber-optic technology to achieve continuous monitoring along the entire fiber line, rather than being limited to a single monitoring point. Distributed acoustic sensing (DAS) and dynamic strain acquisition technologies enable real-time data collection and transmission. This distributed fiber-optic technology enables comprehensive monitoring of pavement over large areas and long distances, overcoming the limitations of traditional point-based sensors and providing a holistic assessment of pavement health.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A distributed optical fiber permanent deformation monitoring method for asphalt pavement under moving load, characterized in that: The steps include: Step 1: Establish a distributed optical fiber deformation monitoring system and lay a single-mode optical fiber in a double-layer asphalt mixture rutting specimen, where the double-layer asphalt mixture rutting specimen includes a first layer rutting plate and a second layer rutting plate; Step 2: Build a strain monitoring system and install full-bridge strain gauges in the double-layer asphalt mixture rutting specimen: Step 3: Data acquisition: using a strain gauge to monitor in real time the optical fiber vibration signal and strain changes of the double-layer asphalt mixture rutting specimen during the standard rutting test when the test wheel moves; Step 4: Data processing: using Matlab data analysis software to process the optical fiber vibration signal and strain change in step 3; Step 5: Establishing a mathematical relationship: Analyze the data change trend of the optical fiber vibration signal and strain change processed in step 4, and establish a mathematical relationship between the two based on the data change trend; Step 6: Establishing the evaluation model: Based on the mathematical relationship in step 5, the distributed monitoring of the permanent deformation of the asphalt pavement under the moving load by the optical fiber vibration signal is realized.

2. The method for monitoring permanent deformation of asphalt pavement under moving load using distributed optical fiber according to claim 1, characterized in that: In step 1, a single-mode optical fiber laying route perpendicular to the test wheel movement direction is set in the laying area on the upper surface of the double-layer asphalt mixture rutting specimen, and an optical fiber groove is engraved along the optical fiber laying route. The single-mode optical fiber is laid straight in the groove, and the optical fiber groove is filled with epoxy resin. After the epoxy resin is cured, a protective shell is formed.

3. The distributed optical fiber permanent deformation monitoring method for asphalt pavement under moving load according to claim 1 is characterized in that: In step 2, the laying position of the full-bridge strain gauge is set on the upper surface of the lower layer of the double-layer asphalt mixture rutting specimen, and a groove matching the size of the full-bridge strain gauge is prepared at the laying position. After laying a layer of fine sand and asphalt at the bottom of the groove, the full-bridge strain gauge is embedded in the groove, and a layer of fine sand and asphalt is laid on the upper part of the full-bridge strain gauge to form a protective layer, and then the second layer of rutting plate is synthesized.

4. The method for monitoring permanent deformation of asphalt pavement under moving load using distributed optical fiber according to claim 1, characterized in that: In step 3, the strain collector is connected to the single-mode optical fiber to ensure stable signal transmission, and the acquisition frequency is adjusted according to the test wheel movement speed and the test piece characteristics to capture the complete vibration signal. During the standard rutting test, the vibration signal generated when the test wheel moves is transmitted to the optical fiber, and the strain collector records these signals in real time; the full-bridge strain gauge is connected to the strain collector to ensure that the strain data collected by the full-bridge strain gauge can be transmitted to the strain collector in real time. During the movement of the test wheel, the strain collector monitors the strain changes of the test piece in real time and records the stress response feedback from the full-bridge strain gauge.

5. The method for monitoring permanent deformation of asphalt pavement under moving load using distributed optical fiber according to claim 1, characterized in that: In step 4, the optical fiber vibration signal is converted from the time domain to the frequency domain through Fourier transform, and the frequency domain feature data is extracted.

6. The method for monitoring permanent deformation of asphalt pavement under moving load using distributed optical fiber according to claim 1, characterized in that: In step 4, the MATLAB data analysis software is used to remove the singular values ​​and abnormal points in the strain change data of step 3.

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