Abstract
Pavement deflection is the primary indicator reflecting road-bearing capacity. The falling weight deflectometer (FWD) and the Benkelman beam deflectometer (BBD) are widely used in deflection measurement, and are suitable for measuring the elastic deflection of pavement under static loading or dynamic impact loading. In recent years, there has been an increasing interest in continuous dynamic deflectometers, especially velocity-based deflectometers. The velocity-based continuous dynamic deflectometers, such as the laser dynamic deflectometer (LDD), are used to solve the problems of traffic speed and non-destructive pavement deflection measurement. However, there can be many deviations caused by the varied environmental parameters in practical application. In this article, through the review of the mechanism of the Euler-Bernoulli beam upon an elastic foundation and the corresponding influencing factors, the internal and external factors causing dynamic deflection measurement deviation are analyzed and summarized. The influences of pavement temperature, vehicle speed, pavement condition, and other factors are summarized and discussed. On this basis, a model of environmental parameter correction for the continuous dynamic deflectometer is established using a regression analysis method. Numbers of experiments confirmed the reliability of the correction model under different measurement conditions. The correlation experiments between the LDD and different types of deflectometer confirmed the accuracy of the correction model under different measurement conditions. The results showed that the correction model for the continuous deflection measurement of pavements under dynamic loads has strong robustness in different environments and conditions.
Highlights
Deflection is an important index reflecting the comprehensive bearing capacity of subgrade and pavement, which is influenced by the compacted material density [1] and material stiffness [2]
Static load deflection measurement and dynamic impact deflection measurement are limited in practical application as they need sufficient response time for the deformation and recovery
Greenwood Engineering of Denmark and ZOYON of China have developed methods based on the velocity-based measurement of pavement deformation and a theoretical model of the deflection value. They produce products such as the high-speed deflectograph (HSD), the traffic speed deflectometer (TSD), and the laser dynamic deflectometer (LDD), which have been successful in both theory and application [14]–[17]
Summary
Deflection is an important index reflecting the comprehensive bearing capacity of subgrade and pavement, which is influenced by the compacted material density [1] and material stiffness [2]. Greenwood Engineering of Denmark and ZOYON of China have developed methods based on the velocity-based measurement of pavement deformation and a theoretical model of the deflection value They produce products such as the high-speed deflectograph (HSD), the traffic speed deflectometer (TSD), and the laser dynamic deflectometer (LDD), which have been successful in both theory and application [14]–[17]. Starting with the analysis of the mechanism of the LDD and the quantitative influencing factors, the potential main influencing factors are considered as the dynamic load, vehicle speed, pavement roughness, and pavement temperature Based on these findings, a recommended correction model for the environmental parameters of the continuous dynamic deflectometer is presented, the feasibility of which was confirmed by repeatability and correlation experiments.
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