The Virginia Smart Road: The Impact of Pavement Instrumentation on Understanding Pavement Performance

摘要

This paper presents the description, calibration procedures,installation, and performance of the instrumentation used at the VirginiaSmart Road to measure flexible pavement response to loading. Alsopresented are the measured horizontal transverse and longitudinal strainsinduced in the hot-mix asphalt (HMA) during compaction with a steeldrum compactor both with and without vibrations. In addition, this paperpresents the data collected and used to determine the verticalcompressive stress pulse induced by a moving truck at different locationsbeneath the pavement surface. These data were also used to determinethe effects of temperature, speed, and tire inflation pressure on themeasured vertical compressive stress and measured horizontal transversestrain, induced by a steering-axle tire of 25.8kN, under the HMA layer.The data were used make a comparison between measured pavementresponses to truck loading with those calculated using linear elastictheory. It was found that HMA is subjected to very high horizontalstrains during compaction—especially when vibration is used. It wasalso found that a haversine equation well represents the measurednormalized vertical compressive stress pulse for a moving vehicle.Haversine duration times varied from 0.02s for a vehicle speed of70km/h at a depth of 40mm to 1.0s for a vehicle speed of 10km/h at adepth of 597mm. As expected, temperature was found to significantlyaffect the measured vertical compressive stress and measured horizontaltransverse strain under the HMA layer. Although speed was found not toaffect the magnitude of the measured vertical compressive stress, it wasfound to affect the loading time. On the other hand, speed was found tosignificantly affect the measured horizontal transverse strain under theHMA layer. Variation in tire inflation pressure from 552kPa to 724kPawas found not to affect the measured vertical compressive stress and themeasured horizontal transverse strain at the bottom of the HMA layer. Acomparison between the measured responses and those calculated using afinite element model that uses linear elastic theory indicated that theelastic theory overestimates pavement responses at low temperatures butsignificantly underestimates these responses at high temperatures. An improved prediction of pavement responses was achieved by modifyingthe bonding conditions at the interfaces, and by modeling HMA as aviscoelastic material.