Quantification of the Dynamic Compressive Response of Two Ottawa Sands

Two types of Ottawa sand (ASTM C778 #20-30 graded sand, denoted OS1, and C109 ASTM #C778 graded sand, denoted OS2) with different particle size distributions were tested in a series of dynamic uniaxial strain experiments using a modified split Hopkinson pressure bar (SHPB) system. The pulse shaper technique was employed to achieve the dynamic force balance and constant strain rate in the sand specimen. The effects of the strain rate, initial void ratio and moisture on the dynamic compression response of sand were examined. Two types of dynamic behavior occurred in the dry sand: solid-like and fluid-like behavior. The OS1 samples exhibited a fluid-like response at all initial void ratios, whereas the OS2 samples exhibited a solid-like response for all void ratios. This difference between the two sands may be due to the difference in the particular size distributions of OS1 and OS2. The initial elastic response of the dry sand samples seemed to be independent of the strain rate. The strain rate effects became more apparent after particle crushing and particle rearrangement began. Under a high degree of saturation, the strain rate effects were immediately apparent, even at lower strains. The dynamic response of sand was remarkably linear until the peak strain was reached.