Monitoring Pavement Response during Spring Thaw Using Fiber-Optic Sensors

Seasonal variation in pavement response is considered to be a major factor affecting pavement performance. Several studies have concluded that in cold climates, most of the pavement damage by fatigue and permanent deformation can be associated with the loss of bearing capacity during spring thaw. The understanding of the bearing capacity loss phenomena needs to be improved and pavement design methodologies dealing specifically with the problem need to be developed. The Quebec Ministry of Transportation, in collaboration with the Laboratoire Central des Ponts et Chaussees (LCPC, France) and Laval University, has undertaken a major research project based on the monitoring of instrumented test sections. Four heavily circulated test sections were constructed and instrumented. Pavement instrumentation includes thermistors, moisture sensors, frost gages, piezometers and heave gauges. Several techniques were used to monitor pavement response during spring. Among others, specially designed strain gauges and multi-depths deflectometers were installed in the test sections. These gauges were built using optic-fibre technology. The paper describes the technology used to develop the new sensors. It also reports on the installation of the instruments and on the measurements taken at the test site under a moving truck during spring thaw. For the covering abstract see ITRD E118503.