Understanding creep dynamics in model earth systems

Wait long enough and everything flows. In the case of "solid" materials, this is achieved by sub-yield deformations – creep. Over time, the effects of creep can significantly reduce material integrity and lead to catastrophic yielding. Understanding the dynamics of creep in systems like soil, sand, cement etc., i.e. granular materials, is important to inform how we work with these systems and prevent effects of catastrophic failure. In this talk, we focus on understanding creep in yield-stress materials. We compare the creep dynamics in a model yield-stress fluid, Carbopol, and a model earth system, Kaolinite + sand. Through rheological measurements and imaging, we analyze how these systems respond to a sub-critical stress. We characterize the power law scaling of creep relaxation and investigate how introducing friction changes the behavior of Carbopol and Kaolinite. We also investigate how the scaling of creep can reveal details about rheological models for yield stress fluids.