| A mathematical framework for large strain consolidation of fully saturated soil is presented in this study. Strong and weak forms of the boundary-value problem are derived using both the material and spatial descriptions. The algorithmic treatment of large strain of the solid phase is based on multiplicative decomposition of deformation gradient and is coupled with the algorithm of fluid flow via the Kirchhoff pore water pressure. Balance laws for saturated soil are written following the classical theory of mixture considering soil-water mixture as a two-phase continuum. Since the motion of the fluid phase only affects the Jacobian of solid phase, balance laws are derived completely in terms of the motion of soil skeleton.; Both geometric and material nonlinearities are incorporated in the stated mathematical model. Geometric nonlinearity is represented by the Jacobian and its variation along with proper stress and strain characterization based on updated configuration. Material nonlinearities of soil skeleton are represented in this study by two different constitutive relations (elastoplastic and viscoplastic) based on modified Cam-Clay (MCC) model of critical state soil mechanics.; Proposed mathematical model is linearized in order to obtain consistent tangent operators and subsequently implemented in a displacement-based finite element code PlasFEM, developed by the Geotechnical Engineering group at the University of Florida. Numerical prediction of primary (consolidation and swell) and secondary (creep) consolidation settlement of phosphatic waste clay, found at the construction site of Polk County Expressway in Lakeland, Florida, in presence of vertical wick drains subject to surcharge loading, unloading and subsequent reloading (i.e. road construction) is conducted using PlasFEM. Simulation results showed a very good agreement with the field measurements. |
