Research on Load-Signal Response of Distributed Optical Fiber Based on Hamburg Rut Test

Abstract

In this paper, the distributed optical-fiber sensing technology is introduced in response monitoring of asphalt pavement under loading. The corresponding immersion monitoring scheme is proposed. To study the change rule of optical-fiber sensing signal in asphalt concrete at different loadings and temperatures, a distributed optical-fiber sensing testing system is established. The system includes the light source, sensing element, asphalt concrete structure, a photoelectric detection module, and a data acquisition module. The encapsulated optical fiber sensor is embedded in the asphalt concrete rutting specimen, and the indoor Hamburg rutting test method is employed. Under different temperatures and different size loads, the rutting specimens are loaded with periodically moving rubber wheels to simulate actual asphalt road traffic loads. Taking the optical fiber signal sensitivity and signal strength as evaluation indicators, the acquired optical fiber signal is defined in two stages: no-load stage and loading stage. The quantitative relationship between fiber signal characteristics, load magnitude, and ambient temperature in two stages are studied. The results show that under the Hamburg rutting test, the fiber signal is steady, and information like the loading characteristics and period characteristics can be obtained from the fiber signal curve. Under 30°C, 45°C, and 60°C, the fiber optic signal sensitivity and load magnitude are linearly correlated. Under the conditions of 45°C and 60°C, the increasing speed of the fiber signal sensitivity with loading is larger than that at 30°C. Compared with high temperature (45°C–60°C), the fiber signal sensitivity value increases faster at low temperatures (30°C–45°C). The higher the temperature, the more dispersed the optical fiber signal sensitivity value distribution. The research results are of great significance to verify and improve the distributed optical fiber technology system in applications of road engineering.