Predominant modes for Rayleigh wave propagation using the dynamic stiffness matrix approach

Abstract

In case of irregular dispersive media, a proper analysis of higher modes existing in a dispersion plot becomes essential for predicting the shear wave velocity profile of ground on the basis of surface wave tests. In such cases, an establishment of the predominant mode becomes quite important. In the current investigation for Rayleigh wave propagation, the predominant modes have been evaluated by maximizing the normalized vertical displacements along the free surface. Eigenvectors computed from the dynamic stiffness matrix (DSM) approach are analyzed to find the predominant mode. The results obtained are then compared with those reported in the literature. By varying the displacement amplitude ratios of the predominant mode to the other modes, dispersion plots have also been generated from the multichannel analysis of surface waves (MASW) method. The establishment of the predominant mode becomes especially significant, where usually only two to six sensors are employed and the governing (predominant) modal dispersion curve is usually observed rather than several multiple modes, which can be otherwise identified by using around 24 to 48 sensors.