Deformation and Stability of Viscoelastic Soil Media

Abstract

Linear viscoelasticity is a more resalistic representation than linear elasticity in studying the deformation and stability problems of saturated cohesive soil media. The linear viscoelastic model is incorporated in terms of volumetric (a single Kelvin unit) and deviatoric (a single Maxwell Unit) components. Elastic-viscoelastic correspondence is utilized to obtain the time-dependent displacement and stress fields. Limitations of the correspondence principle are investigated quantitatively in parallel to stress level and overconsolidation ratio. Factor of safety for stability is considered as the ratio of the time-dependent octahedral shear strength to the time dependent octahedral shear stress. This in turn leads to the observation that a viscoelastic medium may experience a stable state (i.e., factor of safety > 1) upon the application of a particular boundary loading and yet, it may bring itself into an unstable state with time (i.e., factor of safety = 1) even though the shear strength is (or is not) exhibiting an increase during the same interval. This is demonstrated for a strip surface loading and a plane strain problem.