Applied Math Seminar

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A thermomechanical model for frozen sediments

Speaker: Colin Meyer

Location: Warren Weaver Hall 1302

Date: Friday, March 25, 2022, 2:30 p.m.

Synopsis:

Ice-infiltrated sediment, known as a frozen fringe, leads to phenomena such as frost heave, ice lenses, and meters of debris-rich ice under glaciers. Understanding the dynamics of frozen fringe development is important as frost heave is responsible for damaging infrastructure at high latitudes; frozen sediments at the base of glaciers can modulate glacier flow, influencing the rate of global sea level rise; and frozen water ice exists within the sediments of the top several meters on Mars and in places on the Moon. Here we study the fluid physics of interstitial freezing water in sediments and focus on the conditions relevant for subglacial and planetary environments. We describe the thermomechanics of liquid water flow through and freezing in ice-saturated frozen sediments. The force balance that governs the frozen fringe thickness depends on the weight of the overlying material, the thermomolecular force between ice and sediments across premelted films of liquid, and the water pressure within liquid films that is required by flow according to Darcy's law. Our model accounts for premelting at ice-sediment contacts, partial ice saturation of the pore space, water flow through the fringe, the thermodynamics of the ice-water-sediment interface, and vertical force balance. We explicitly account for the formation of ice lenses, regions of pure ice that cleave the fringe at the depth where the interparticle force vanishes.