An empirical approach for the quantification of uniaxial compressive stress-strain of partially saturated granular media under high strain rates

Abstract

While it is qualitatively known that the dynamic stress-strain response of granular media is highly influenced by the initial density and moisture content, a detailed characterization of such behavior has not been reported in the existing literature. This paper proposes a simplified empirical approach to quantify the uniaxial compressive stress-strain behavior of partially saturated granular media at a given saturation and initial dry density that requires only the response at a reference dry density as input. The relations were formulated based on experimental stress-strain data of Stockton Beach sand retrieved using a modified split Hopkinson pressure bar (SHPB) at a strain rate between 1000 and 1300 s⁻¹. The tested sand was confined within a hardened steel tube, exhibiting initial dry densities of 1.46 g/cm³, 1.57 g/cm³, and 1.69 g/cm³ across water saturations ranging from dry to above 90%. Through a parametric investigation, the resulting empirical relations were shown to be promising in representing the specimen behavior before and after the initiation of water lock-up. This study ultimately illustrates the feasibility of empirical modeling techniques in predicting and characterizing the high strain rate response of partially saturated granular media as a bulk system.