Frequency Response of Layered Media under Different Conditions of Interlayer Adhesion by the Example of Road Pavement

The dynamic response of a layered medium (using road pavement as an example) to a dynamic impact for the conditions of cohesive contact between individual layers and complete slippage is analyzed. To solve this problem, a mathematical model of the dynamic stress-strain state of a layered half-space is used, based on solving the Lamé equation in displacements, using the Hankel integral transform, amplitude–frequency characteristic (AFC) of accelerations on the medium surface under study, obtained directly from the displacement AFCs. In the course of a numerical experiment on this model, it is found that the case of adhesive contact between the layers of the road pavement corresponds to the presence of one clearly expressed frequency extremum on the acceleration AFC. The case of “complete slippage” corresponds to the presence of a number of frequency extrema on the acceleration AFC. In this case, when modeling the full slip at the boundary of the half-space lower layer and the underlying half-space and varying the elastic modulus of the half-space, the presence of a clearly defined frequency extremum in the range of 426–531 Hz is noted, presumably corresponding to oscillations of the underlying half-space itself. The established patterns can be used to improve the methods and means of non-destructive testing of layered media, in particular to increase the information content of their structural state, which is necessary for making decisions on repair or overhaul.