Assessing Persistence of Entrapped Gas for Induced Partial Saturation

Abstract

Induced partial saturation (IPS) is a novel method to suppress the generation of excess pore-water pressure and increase the liquefaction resistance of loose granular soils. Mechanical benefits associated with IPS are linked to the persistence of entrapped bubbles. Civil infrastructure operates for decades, often longer than a century, and thus the longevity of gas is a salient consideration for adoption of IPS in practice. Modeling the physical and chemical mechanisms that influence the persistence of entrapped bubbles is a practical avenue to address gas durability on these time scales, a limitation of physical experiments. The governing aqueous-phase advection-diffusion processes and interphase gas kinetics associated with bubble dissolution are simulated in a finite-difference numerical framework, validated with elemental and bench-scale experiments, and then extended to address soil resaturation rates under different subsurface conditions. The study demonstrates that emplaced gas is durable to the extent where diffusion-induced and groundwater seepage-induced dissolution should not discourage advancement of IPS, but will not remain indefinitely. Potential solutions to mitigate the decay of a gassy soil layer are discussed.