STUDY OF PORE PRESSURES INDUCED IN LABORATORY DYNAMIC CONSOLIDATION

Knowledge of the pore pressure behavior during dynamic impacts on mode rately low permeability soils is essential in averting possible liquef action and effective field implementation of dynamic consolidation. Al though field observations of dynamically induced pore pressures are ab undant in the literature, analytical or numerical approaches for pore pressure prediction are scarce. Herein, the authors advance a simple t echnique to analytically model the laboratory dynamic consolidation by modifying the classical Terzaghi's static consolidation theory. Since the analytical prediction of dynamic surface stress and experimental verification are performed in a companion paper, the surface stress du e to a dynamic impact is assumed to be known in this work. Then, the t ime dependent stress pulse is de-synthesized into a number of constant load steps to predict the subsequent pore pressure behavior. Since th is methodology accounts for even the dynamic stress attenuation within the soil sample, a rigorous closed form solution has to be replaced b y a numerical solution. It is shown how this solution rapidly converge s when the load steps are made sufficiently small. Finally, the analyt ical predictions of dynamic pore pressure are verified by well control led laboratory experiments performed on a special apparatus set up at the University of South Florida.