Effect of Particle Size on the Compressive Behavior of Dry Sand under Confinement at High Strain Rates
Dynamic compressive behavior of dry sand (Quikrete #1961 sand quarried in Pensacola, FL) under confinement was characterized using a split Hopkinson pressure bar (SHPB). The as-received dry Eglin sand was sieved into different grain sizes, following the A
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Effect of Particle Size on the Compressive Behavior of Dry Sand under Confinement at High Strain Rates Hongbing Lu, Huiyang Luo, William L. Cooper, and Ranga Komanduri
Abstract Dynamic compressive behavior of dry sand (Quikrete #1961 sand quarried in Pensacola, FL) under confinement was characterized using a split Hopkinson pressure bar (SHPB). The as-received dry Eglin sand was sieved into different grain sizes, following the ASTM D2487 standard. The sand were sorted into 0.60, 0.50, 0.42, 0.30, 0.212, 0.15, and 0.106 mm grains through a set of ASTM E11 sieves of #30, #35, #40, #50, #70, #100 and #140, respectively. Sand grains were confined inside a hollow cylinder of hardened steel and capped by cemented tungsten carbide cylindrical rods. This assembly was subjected to repeated manual shaking to consolidate sand to attain the desired bulk mass densities. It is then sandwiched between incident and transmission bars on SHPB for dynamic compression under high strain rate. Sand specimens of seven particle sizes (shaking into maximum mass density) were characterized to determine the volumetric and deviatoric behaviors at high strain rates, and the particle size effect was discussed. The stress-density relationship and the specific energy absorption were determined as a function of sand grain sizes. The void ratio-axial pressure relationships (e-log p curves) were obtained and the compressibility of sand was determined as a function of sand particle sizes. Keywords Long split hopkinson pressure bar (SHPB) • Granular materials, dynamic compaction • Confinement • Hydrostatic pressure
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Introduction
Dense compacted sand has high compressive strength and high energy absorption capacity. Sand is often used to provide bulk ballistic protection for military structures, and as construction materials widely used in civil engineering structures and highways. Numerous researches on the behavior of sand for geological and civil engineering applications focus primarily on the mechanical behavior at low stress levels and under quasi-static loading conditions [1–4]. Its mechanical behavior under relatively high stresses and high strain rates has not been well understood, due that the experimental technique at that time encountered more difficulties in dynamic characterization of sand than in quasi-static tests. Recently, Luo and Lu et al., successfully resolved this difficulty on the preparation of sand samples with consistent mass densities for dynamic compression on a split Hopkinson pressure bar (SHPB) [5]. The mechanical behaviors of sand and soil have been characterized at high strain rates for moisted water [6], soft soil [7], clayey/silty soil [8], and dry sand [9], etc. However, the pioneer data on sand/soil at high strain rate may be suspectible due to the shortcoming of dynamic experimental technique then. Pulse shaping techniques, developed in recent years for SHPB, can facilitate in establishing dynamic equilibrium and constant strain rate conditions necessary in a valid dynamic
H. Lu (*) • H. Luo Department of M
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