Improved parameterization to invert Rayleigh-wave data for shallow profiles containing stiff inclusions

Abstract

Inversion of shear-wave velocity profiles from phase-velocity measurements of Rayleigh-wave energy for sites containing stiff layers can be erroneous if such layers are not characterized in the starting or reference model. Incorporation of a priori knowledge then is key for converging upon a realistic or meaningful solution. Resolving soil profiles in desert regions where stiff layers cemented with calcium carbonate are intermixed with softer, uncemented media is an application for which locating shallow stiff inclusions has important implications. Identification of the stiff layers is critical for foundation design and cost estimating of excavations. A parameterization that seems adequate for this problem is to solve for anticipated high-stiffness layers embedded in a coarser (background) profile that captures the general shear-wave velocity trend of the study area. The optimization is accomplished by using simulated annealing. Uncertainty measures resulting from the inversion are helpful for describing the influence of the parameterization on final model estimates.

Rayleigh-Wave Dispersive Energy Imaging Using a High-Resolution Linear Radon Transform

“…Multichannel Analysis of Surface Waves (MASW) analysis is an efficient tool to obtain the vertical shear (S)-wave velocity profile (e.g., MCMECHAN and YEDLIN, 1981;SONG et al, 1989;XIA et al, 1999XIA et al, , 2002aXIA et al, , b, 2006aPARK et al, 1999;CALDERóN-MACíAS and LUKE, 2007;LUO et al, 2007). Large amplitudes of surface waves allow accurate reconstruction of shallow structures in a noisy environment via inversion of observed dispersion curves (XIA et al, 2004).…”

Dipping-interface Mapping Using Mode-separated Rayleigh Waves

“…Multichannel analysis of surface waves (MASW) method is a non-invasive geophysical technique that uses the dispersive characteristic of Rayleigh waves to estimate the vertical shear (S)-wave velocity (SONG et al, 1989;XIA et al, 1999XIA et al, , 2002aXIA et al, , b, 2006PARK et al, 1999;CALDERÓ N-MACÍAS and LUKE, 2007;LUO et al, 2007). A pseudo-2D S-wave velocity section is constructed by aligning 1D models at the midpoint of each receiver spread and using a spatial interpolation scheme XIA et al, 2005; An appealing solution to efficiently image dispersive energy and separate multimode Rayleigh waves can be obtained by high-resolution LRT (SACCHI and ULRYCH, 1995;SCHONEWILLE and DUIJNDAM, 2001;TRAD et al, 2002TRAD et al, , 2003ETHAN and MATTHIAS, 2006).…”

Generation of a pseudo-2D shear-wave velocity section by inversion of a series of 1D dispersion curves

“…Multichannel Analysis of Surface Waves (MASW) analysis is an efficient tool to obtain a vertical S-wave velocity profile (Song et al, 1989;Park et al, 1999;Xia et al, 1999Xia et al, , 2002aXia et al, ,b, 2006Calderón-Macías and Luke, 2007;Luo et al, 2007). The large amplitude of surface waves allows an accurate reconstruction of shallow structures in a noisy environment by inversion of observed dispersion curves.…”