The Spectral-Analysis-of-Surface-Waves (SASW) method is an in situ seismic method that permits detailed profiles of small-strain moduli to be determined at both soil and pavement sites. The method, which is nondestructive, is based on the dispersive characteristic of surface (Rayleigh) waves propagating in a layered medium. One of the principal advantages of this method is that all testing is performed on the ground surface. A second advantage for evaluating the properties of pavement systems is that the method can be used to determine the stiffness of the subgrade before, during, and after placement of the pavement system. These advantages are illustrated using a series of tests on a silty clay subgrade performed before and after placement of a concrete slab 10 in. (0.25 m) thick. A sensitivity study of the subgrade measurements and a method of characterizing nonlinear subgrade behavior are also presented.
Samenvatting