DETERMINATION OF IN SITU SHEAR WAVE VELOCITIES FROM SPECTRAL ANALYSIS OF SURFACE WAVES

Abstract

A method for determining elastic moduli at soil and pavement sites was proposed and tested. Surface receivers were utilized to evaluate the Rayleigh wave motion created by a vertical, impulsive source that could excite a wide range of frequencies with a single impact. Analysis was facilitated by using a portable spectral analyzer to study the magnitude and phase of the frequency content of the recorded wave pulse. Results from field testing at two flexible pavement sites and two soil sites indicate that the spectral analysis of surface waves provides an accurate estimation of the velocity (and hence modulus) profile at a site. Moduli calculated from wave propagation velocities were generally comparable to moduli calculated by deflection measurements from Dynaflect testing. (FHWA)