Mechanical vibration responses of snow samples near the melting temperature

Abstract

AbstractMechanical properties of snow were investigated by means of a vibration response technique in a frequency range from 10Hz to 1MHz and a temperature range from –15° to –0.1°C with heating and cooling processes. The response signals were divided into two kinds of propagation, transverse and longitudinal waves through the snow sample. The temperature dependence of elastic-wave velocities showed a large decrease above –0.6°C. Poisson’s ratio and Young’s modulus of snow samples were derived from the longitudinal and transverse wave velocities. Poisson’s ratio of snow samples showed a value of 0.35 ± 0.01 below –0.6°C, and dropped to 0.29 or less at –0.1°C. Young’s modulus of snow samples at –0.1°C showed values seven-tenths as large as (25–34%less than) those below –0.6°C. These phenomena suggest weakening and slipping of boundaries between ice particles in snow samples near the melting temperature. The elastic-wave velocities and Young’s modulus change with the density of samples and with time and temperature cycling. These changes are related to the number and state of bonds between ice particles in snow samples.