Dissipation of dynamic deformation energy in pavements of automobile roads

Introduction. The network of highways is one of the factors ensuring sustainable development of both plain and mountainous territories. Effective monitoring of road condition using modern non - destructive methods is an integral element of ensuring their normative condition. One of the promising ways to improve nondestructive testing methods is the energy approach based on the indicator of dissipation of deformation energy. Methods. The mathematical model considered in this paper is based on the solution of the system of dynamic Lame equations in displacements. The solution is constructed by applying the properties of the Fourier transform, and methods of discrete harmonic analysis. The output data are the amplitude - time and amplitude - frequency characteristics of the displacements on the pavement surface. The elastic properties of pavement layers are described by the elastic moduli and Poisson’s coefficients of the layer materials, and the viscous properties by the tangents of the loss angles of longitudinal and transverse waves. Results and discussion. A numerical experiment was carried out to investigate the influence of elastic and viscous characteristics of pavement layers on the value of strain energy dissipation. The values of strain energy dissipation were calculated by dynamic hysteresis loops obtained by superimposing the amplitude - temporal characteristic of the shock loading impulse on the amplitude - temporal characteristic of displacements on the pavement surface. It was found that varying the elastic modulus of asphalt concrete has the greatest effect on the amount of energy dissipation in the zone from 0 to approximately 1.8 m from the point of impact load application. The modulus of elasticity of the base layer affects the change in energy dissipation in the entire study area, gradually converging to zero at a distance of 2.1 m from the point of impact loading. The modulus of elasticity of the working layer of the subgrade has a significant effect on the energy dissipation in the whole investigated area. Viscous characteristics have much less influence on the energy dissipation value in some cases leading to qualitative changes in its distribution. Conclusion. The obtained results can serve to improve the existing methods of nondestructive testing of road pavements, in particular, when developing effective procedures for correcting the parameters of the calculated response relative to the experimental one.