Response of moist sand to high rate loading

Abstract
The dynamic response of sand has predominately been characterized at dry and saturated conditions, but much less studied at moist or partially saturated conditions. This work is to aid in better understanding the dynamic behavior of partially saturated sand. In particular, the effects of moisture on the dynamic behavior of poorly graded, silica based sand are explored using a modified Kolsky bar. A controlled loading pulse (pulse shaping) allowed the sample to acquire stress equilibrium and a constant strain-rate. The experiments were conducted at strain-rates of 900 s⁻¹ and 1500 s⁻¹ with the sand specimen passively confined in a hardened steel tube. The sand has a dry density of 1.50 g/cm³ with its moisture contents varying from 0% to 9% by weight. Experimental results indicate that partially saturated sand is more compliant than dry sand. The softening of the partially saturated sand may occur due to the pore water acting as a lubricant between the sand particles.