Pore Pressure Dissipation Behavior Surrounding Driven Piles and Cone Penetrometers

Driven piles are a common foundation used to support highway bridges. Data gathered from instrumented piles and piezocone tests in finegrained soils indicate that variable pore pressure profiles, which depend on the overconsolidation ratio of the soil, can develop during penetration. For piles driven in soft clays and silts, the pore pressure profiles developed show a monotonically decreasing response with time. However, for piles driven in heavily overconsolidated silts and clays, the pore pressure profiles show dilatory behavior, with the pore pressure behavior increasing from the initial measured value to a maximum, and then decreasing to hydrostatic values. A theoretical framework is presented that combines cavity expansion theory and critical state soil mechanics with an analytical solution to the radical consolidation equation to estimate the pore pressure response as a function of time and to evaluate the coefficient of consolidation of fine-grained soils on the basis of instrumented pile and piezocone data. The method is able to describe the pore pressure response curve in soils that demonstrate either monotonically decreasing or dilatory pore pressure behavior. Driven pile data from three sites are used to verify the estimations of the model.