Parameter Estimation in Finite Element Simulations of Rayleigh Waves

Abstract

Spectral analysis of surface waves measurements are used to develop subsurface soil profiles or as a tool to delineate abandoned crown pillar structures. Finite element modeling of Rayleigh waves has practical application in simulating SASW measurements. Developing a reliable and accurate finite element model to simulate Rayleigh waves requires the proper mesh dimensions and attenuation parameters. This research proposes a new simplified methodology for quantifying mesh dispersion effects. In addition, methods of verifying damping ratios for numerical simulations are presented. The evaluation of an array of nodal displacements in the frequency–wave-number domain effectively illustrates mesh dispersion effects and the presence of parasitic modes of vibration. Calculations of damping ratio show that mass and stiffness damping parameters are valid within a specified frequency bandwidth. The new techniques are tested for a half-space model; however, they can be used for the analysis of layered media. In addition, equations are given for the calculation of linear Rayleigh damping. These equations satisfy the conditions of an average damping with minimum variance within the frequency bandwidth of interest.