Surface‐Wave Dispersion in Partially Saturated Soils: The Role of Capillary Forces

Improving our understanding of the relation between water content and seismic signatures unconsolidated superficial soils is an important objective in overall field hydrogeophysics. Current approaches to constrain vadose zone from data are based on computing ratio compressional shear wave velocities Vp/Vs. While this allows for detection pronounced changes saturation, such as groundwater table, it essentially insensitive variations saturation-depth profile. Conversely, evidence shows that surface waves sensitive both location table Classic rock physics models unable explain corresponding observations. We propose estimate surface-wave accounting capillary suction effects. extend Hertz-Mindlin model using Bishop's effective stress definition, thus stiffness associated with stresses acting soil's frame. then compute elastic properties partially saturated medium Biot-Gassmann-Wood model. Considering a 1D porous under steady-state saturation conditions, given by Richards' equation, we simulate body-wave travel times dispersion characteristics different depths overlying soil textures. Our results illustrate phase velocity curves remarkably effects soils, exhibiting up 20% 10–100 Hz frequency range. These effects, which particularly medium-to fine-grained virtually nonexistent Vp/Vs profiles.