Pore water pressure response of soil subjected to dynamic loading under saturated and unsaturated conditions

This study presents the results of one of the first attempts to characterize the pore water pressure response of soils subjected to dynamic loading under saturated and unsaturated conditions. The resilient modulus, which captures the soil stiffness under dynamic loading, is a critical parameter for pavement design. It has been recognized that the development of pore water pressure contributes to modulus degradation. Several efforts have been directed to model the effect of air and water pore pressures upon the modulus. However, none of them considered dynamic changes in pressures but rather were based on equilibrium values corresponding to either initial or final conditions. A testing program was conducted to characterize the pore water pressure response of a clayey sand subjected to dynamic loading. Using the results, models capable of predicting the cumulative excess pore pressure under both saturated and unsaturated conditions were proposed. Findings regarding the influence of the controlled variables challenge common beliefs. Upon further research, the proposed models may become a powerful tool not only to overcome unsaturated soil testing limitations, but also to prevent soil failure as a result of excessive pore water pressure development.