USE OF SPECTRAL ANALYSIS OF SURFACE WAVES METHOD FOR DETERMINATION OF MODULI AND THICKNESSES OF PAVEMENT SYSTEMS.

Abstract

The spectal analysis of surface waves (SASW) method is a nondestructive method for determining moduli and thicknesses of pavement systems. By means of a transient impact on the surface of a pavement system (or soil deposit), a group of waves with different frequencies is transmitted to the medium. Seismic wave velocities and, eventually, elastic moduli and thicknesses of the various layers in the pavement system are determined from analysis of the phase information for each frequency determined between two receivers located on the surface. The method has several advantages: it is nondestructive, has a unique solution, and is capable of full automation. The results of three series of tests performed on TX-71 near Columbus, Texas, are presented. Testing was performed on an asphaltic concrete pavement, a continuously reinforced concrete pavement, and a natural soil occupying the median at the site. Elastic moduli determined by using the SASW method are compared with those determined by means of crosshole seismic tests and Dynaflect measurements. Moduli determined by the SASW method are in agreement with those from crosshole tests, whereas moduli back-calculated from Dynaflect measurements compare rather unfavorably with moduli determined by the other two methods.