Monitoring of pavement deflections using geophones

ABSTRACT

The paper presents tests performed on an instrumented motorway section, to monitor traffic and pavement deflections using geophones. Geophones are sensors used to measure displacement velocities, and by integrating their signal, it is possible to monitor vertical displacements. In this study, 4 geophones have been installed in the base layer of the pavement, and their measurements have been recorded under real traffic, during a period of approximately 18 months, using a remote control data acquisition system, transferring the data to a server. Different methods of treatment of the geophone measurements have been proposed: the first application concerns the detection of different heavy vehicle silhouettes, by analysing the number of peaks of the displacement signals; the second application concerns the measurement of vehicle speeds, by determining the time difference between the measurements of two geophones. The third application concerns the measurement of pavement deflections. To measure accurately the deflection, a procedure has been developed, to correct the geophone response, which is attenuated in the low frequency range. This procedure has been validated by measurements under controlled loading conditions, on the IFSTTAR accelerated pavement testing facility, and then applied to in situ measurements. In conclusion, the study shows that geophones, which present the advantage of being relatively inexpensive and robust sensors, offer interesting possibilities for pavement monitoring.

KEYWORDS:

• Pavement monitoring
• remote monitoring
• geophone
• data acquisition
• deflection

Disclosure statement

No potential conflict of interest was reported by the author