Wanqiu Liu

Functionality Enhancement of Industrialized Optical Fiber Sensors and System Developed for Full-Scale Pavement Monitoring

Pavements always play a predominant role in transportation. Health monitoring of pavements is becoming more and more significant, as frequently suffering from cracks, rutting, and slippage renders them prematurely out of service. Effective and reliable sensing elements are thus in high demand to make prognosis on the mechanical properties and occurrence of damage to pavements. Therefore, in this paper, various types of functionality enhancement of industrialized optical fiber sensors for pavement monitoring are developed, with the corresponding operational principles clarified in theory and the performance double checked by basic experiments. Furthermore, a self-healing optical fiber sensing network system is adopted to accomplish full-scale monitoring of pavements. The application of optical fiber sensors assembly and self-healing network system in pavement has been carried out to validate the feasibility. It has been proved that the research in this article provides a valuable method and meaningful guidance for the integrity monitoring of civil structures, especially pavements.

The behavior of a novel raw material-encapsulated FBG sensor for pavement monitoring

Technology on pavement monitoring has been paid more and more attention by government, engineers and scholars. Conventional methods, such as artificial inspection and core sampling, have defect in low efficiency and limited coverage, and modern technologies, such as spectrum analysis and integral imaging, have poor resistance to external interference and high cost, which reveals that common approaches have fallen behind the development of road engineering. Therefore, a novel raw material-encapsulated FBG strain sensor is put forward, thinking over outstanding advantages of fiber Bragg grating and perfect incorporation between coating layers and host layers. Numerical analysis and experiments have been done to inspect behavior of the sensing system. Results indicate that it can well detect the actual performance of pavements, and the sensor presents a high-precision, real-time and long-term monitoring, owning function of road disaster warming, which promise it an extensive future in pavement monitoring.

Optical fiber based sensing system design for the health monitoring of multi-layered pavement structure

This paper introduces an optical fiber based sensing system design for multi-layered pavement structural health monitoring. The co-line and integration design of FBG (Fiber Bragg Gating) sensors and BOTDR (Brillouin Optical Time Domain Reflectometry) sensors will ensure the large scale damage monitoring and local high accurate strain measurement. The function of pavement structure multi-scale shape measurement will provide real time subgrade settlement and rutting information. The sensor packaging methodology and strain transfer problem of the system will also be discussed in this paper. Primary lab tests prove the potential and feasibility of the practical application of the sensing system.

Design and Testing of a Large-Scale Shape-Monitoring Sensor Based on Fiber-Bragg-Grating Sensing Technique for Pavement Structure

AbstractOn-site pavement structural-performance monitoring is a challenging task. High accuracy, large coverage, and good reliability of the embedded sensors are the key factors to ensure monitorin...

Distributed pavement subgrade shape monitoring based on FBG sensing technique

It is often difficult to monitor the subgrade performance of an in service highway structure due to its depth and large in size. Traditional sensors for pavement performance monitoring are usually point-wise sensors and therefore cannot fulfill the requirement for large coverage. This paper introduces a shape measurement sensor based on Fiber Bragg Grating (FBG) sensing technique for pavement structure developed by our research group. It can provide large-scale layer shape measurement using only one FBG sensing element and can bear the high compaction force and high temperature during pavement construction. The proposed sensor has been test in lab to show high accuracy in measurement. In the construction of the He-da highway in Jilin province, the proposed sensor has been applied to monitor the subgrade performance for the first time. Ten sets of the sensors with individual length of about 15 m have been embedded and the performance data have been collected twice. The embedding process and monitoring data will be introduced and discussed. The results have shown the potential of the proposed sensor for future large scale application.

Performance of a movable flexible pipe-encapsulated FBG sensor developed for shape monitoring of multi-layered pavement structure

The large span and heterogeneous components of multi-layered pavement structure usually bring about stochastic damage, and many modern approaches, such as ground penetrating radar, integral imaging and optical fiber sensing technology, have been employed to detect the degeneration mechanism. Restricted by the cost and universality, novel elements for pavement monitoring are in high demand. Optical fiber sensing technology for high sensitivity, long stability, anti-corrosion and resistance to water erosion then is considered. Therefore, a movable FBG sensor located in flexible pipe is developed, which has long stroke inside inner wall of the hollow pipe, and a full-scale shape of the structure could be sketched just with one FBG. Theoretical and experimental methods about establishing the relationship between wavelength variable and curvature have been provided, and function about reconfiguring the coordinate is converted to a mathematic question. Move over, transfer error modification has been taken into account for modify related error. Multi-layered pavement model embedded with this sensor will be accomplished to inspect its performance in later work. The work in the paper affords a feasible method for shape monitoring and would be potentially valuable for the maintenance and inverse design of pavement structure.

Strain transfer error analysis of optical fiber sensors with local debonding interface

Structural health monitoring has become more and more popular in application of damage diagnosis and safety assessment. Optical fiber sensors, as one of the most efficient sensing elements, for the superior advantages of long-term stability and durability, good geometrical shape-versatility, corrosion resistance and anti-electromagnetic interference, are widely used in diverse technological fields. Measurement precision of the sensor is thus emphasized and strain transfer analysis put forward to explain the action mechanism and improve the test accuracy. Theoretical derivation on strain transfer error analysis of optical fiber sensor applied to structure with local debonding interface is carried out in this paper. Cases that optical fiber sensors are bonded on the surface of structure and embedded in structure are discussed, respectively, and related error modification functions are provided. The research is meaningful for improving the precision of optical fiber sensors applied to structures with the existing of local debonding interface, which will be ultimately serve for showing true mechanical state of structures.