A study on issues relating to testing of soils and pavements by surface wave methods

Abstract

A study on the differences between testing soils and pavements using surface wave methods is presented. The differences in theoretical dispersion curves are illustrated using the transfer matrix method and the stiffness matrix method for soils and pavements, respectively. The Levenberg-Marquardt and simulated annealing methods are applied for inversion of experimental data on soils and a concrete foundation slab, and the relative merits and differences of the two inversion methods are discussed.

Improving performance and sustainability of unpaved roads: Stabilization and testing

“…In contrast to conventional seismic reflection and refraction methods, the MASW test is capable of measuring modulus profiles of stiff over soft layers (Lin and Ashlock 2011). When applying traditional surface wave analysis methods to pavement systems, several challenges are encountered such as numerical instability when using the transfer matrix method to calculate theoretical dispersion curves at high frequencies, and convergence to a local minimum when using the Levenberg-Marquardt method for inversion (Lin and Ashlock 2011).…”

“…Surface wave methods employ the phenomenon of dispersion of surface waves in layered elastic media, to infer the layer properties (e.g., thickness and modulus) by matching experimental dispersion curves to their theoretical counterparts (Park et al 1998;Park et al 1999;Xia et al 1999). In contrast to the conventional seismic reflection and refraction methods, SWM are capable of measuring modulus profiles of stiff over soft layers (Lin and Ashlock 2011), which applies to both paved and unpaved roads which typically possess stiffer surface courses over softer subgrade layers. In MASW tests, an impact is applied on the ground surface to generate surface waves (e.g., Rayleigh waves for regular profiles with depth-wise increasing stiffness, or quasi-Lamb waves when the stiffest layer is on the surface), and the surface wave motion is measured using an array of geophones or accelerometers (Park et al 1999).…”

“…Based on dispersion characteristics contained in the measured surface motion, the shear wave velocity as a function of depth can be back-calculated through an inversion procedure. However, when applying traditional surface wave analysis methods to pavement systems, several challenges are encountered such as numerical instability when using the transfer matrix method to calculate theoretical dispersion curves at high frequencies, and convergence to a local minimum when using the Levenberg-Marquardt method for inversion (Lin and Ashlock 2011).…”