On the High Strain Rate Response of Partially Saturated Porous Media

Abstract

Exploring the dynamic response of porous media is of paramount importance across industrial sectors ranging from civil engineering to defence. However, the behaviour of porous media under high strain rate loading is infrequently characterised and poorly understood. The incorporation of water giving rise to a partially saturated state further exacerbates the challenges in evaluating the response of such materials under dynamic conditions. This dissertation aims to address current deficiencies in contemporary knowledge by exploring the compressive high strain rate behaviour of partially saturated porous media via experimental testing using a modified split Hopkinson pressure bar. Materials consisting of Sydney sand, poorly graded glass beads, and well graded glass beads are examined under strain rates ranging from 800 s-1 to 2100 s-1 at saturations from 0% to above 90%. It was identified that the stress-strain response is highly complex and sensitive to multiple controlled parameters including strain rate, grain shape, specimen gradation, initial dry density, and confinement environment, which are all in turn further influenced by the degree of saturation. The energy density and extent of grain crushing in relation to the saturation, initial dry density, and lateral confinement environment were also quantified to further understand the role of pore water in influencing the energy absorption and breakage of particles under high strain rate loading conditions. Experimental results extracted as part of this study will effectively aid in the development and calibration of multi-scale multi-phase constitutive mechanical models with the potential for implementation throughout engineering practice.