Numerical Simulation of the Influence of Initial State of Sand on Element Tests and Micropile Performance

This paper presents a state-dependent constitutive model for sand formulated within the critical-state framework and its implementation into a numerical analysis (FLAC3D) program. The implemented model was verified by using drained triaxial results on sands. The proposed model is shown to capture the stress path dependent behavior of sand over a wide range of densities and confining pressures well based on a unique set of parameters. Numerical simulations of the behavior of a micropile under vertical loading shows that the side and tip resistance, and thus the total resistance of the pile, are functions of the "in situ state" of soil as defined by the kstate parameter phi = e - e(c) in which e is the void ratio and e(c) the void ratio at the critical state. (C) 2011 American Society of Civil Engineers.