Full-waveform inversion for imaging spatially varying subsoil density

Abstract

Bulk density (ρ) of soil is an important parameter that reflects the ability of the soil to provide structural support, solute and water transport, and soil aeration. Subsoil density generally exhibits significant spatial variation, which is vital information to simulate water/solute movement in soils, to evaluate embankment stability, estimate groundwater effects for predicting crop productivity, and forecast the seismic site response, among others. Density of soil can also vary with time. With rapid climate change and growing use of the underground space, change of soil density at a given location can eventually increase soil vulnerability, eventually causing structural failure and ground collapse. There are several established approaches to measure density in the field or in the laboratory on soil samples. Those approaches cannot generally capture the spatial variability of density, and often the estimates do not represent the undisturbed soil condition. There are several surface geophysical methods that do capture the lateral variability of density in a noninvasive manner, but they either lack in resolution, or being indirectly linked to density, require empirical relations to derive density, or are essentially based on the assumption of an one-dimensional (1D) earth structure....