A Coarse-grained Approach to Simulating Smectite Clay Particles and Broader Implications in Historical Preservation

Abstract

Clay swelling is an abundant process that occurs in geological subsurfaces around the world, in some cases expanding the volume of a clay layer by as much as 15 times its original volume, causing critical damage to infrastructure and subsurface machinery like oil drills. Molecular dynamics modeling allows us to better understand this process at the nanoscale, but has not yet allowed us to fully account for atomistic effects on the macro-scale. The aim of this study is to identify existing gaps in current molecular dynamics modeling methods and employ a coarse-grained model that fixes those gaps and is thus more accurate and more efficient at large scales. By successfully developing this model, we are able to gain a more accurate understanding of clay swelling, which allows us to better estimate clay mechanical properties like hydraulic conductivity, permeability, consolidation, and swelling pressure. This study proposes a continuum solvent approach as well as a coarse-graining method for clay particles, ultimately resulting in a more efficient modeling technique than its atomistic counterpart. Employing these new methods of coarse-graining could enable more accurate modeling of clay swelling on larger scales, thus constructing a better understanding of macro-scale clay swelling and abating the risks associated with employing less accurate models to inform large-scale processes like oil drilling and carbon capture. In addition, these methods allow us to better understand the role of clay swelling properties in the specific case of clay barrier protection to prevent groundwater intrusion in historic buildings, ultimately reframing our understanding of sustainability in the context of historic preservation.