Investigating the Effect of Pore Fluids on the Stability of Unsaturated Geomaterials

Northwestern University, Evanston IL

Investigators

Abstract

The key objective of this project is to investigate the stress-strain response of multiphase geomaterials and elucidate the mechanical implications of natural and/or artificial alterations in the state of the pore fluids. The multiphasic connotation of geomaterials makes their pore network a convenient setting for the physical interaction among constituents and plays a crucial role on how these materials deform and fail under stress. Rain infiltration, water table fluctuations and injection/extraction of fluids are only some examples of the remarkable interaction between geological materials and the interstitial fluids. There is therefore a pressing need for predictive theories explaining how changes in volume fractions and pore pressures can generate unexpected failures. The study will be based on the combination of advanced constitutive models for multiphase geomaterials and the mathematical theory of bifurcation. For this purpose, the predictive capabilities of modern modeling approaches will be discussed from a theoretical standpoint, with the goal of identifying the hydro-mechanical mechanisms that can originate failure in geotechnical materials. This research will contribute to an improved understanding of the mechanics of failure in geomaterials and has the potential to bridge the gap between the mechanical theories for multiphase media and the fundamental concept of material stability. These advances are important to extend to general saturation conditions a series of tools currently available only for fully saturated geomaterials and devise novel strategies for predicting the initiation of unstable mechanisms. The benefits of the research to society will be a better understanding of the mechanisms that govern the occurrence of geo-hazards, novel modeling tools for the design of geotechnical infrastructures and improved predictions of the consequences of multiphase flow across geological formations.