Impact Behavior of the Active Zone within a Frozen Soil Profile

摘要

The report describes a lab experiment with a pavement profile subject to afreeze/thaw cycle. The 5 x 5 x 5 ft lab specimen was instrumented with thermocouples, resistivity sensors, and 48 embedded geophones. The records of these sensors were used to delineate the progress of a freezing front through the soil profile and to implement a tomographic survey. At selected intervals, a 550-lb impulse, lasting 15 milliseconds, was imparted on a circular plate placed on the surficial asphalt layer, and the records at all geophone locations were recorded. The surface deflection bowl was used to backcalculate the moduli of all pavement layers present using a computer code, WESDEF. Then the two sets of moduli from WESDEF and those found from the tomographic survey were used to predict the deflections at all geophone locations. The report describes the comparison of the measured with the predicted deflections to evaluate the capabilities of the backcalculation procedure in the presence of frozen and thawed soil layers. (MM).