An Evaluation of Shock Waves in Unsaturated Wet Snow

Abstract

The propagation of shock waves in unsaturated wet snow is investigated, both analytically and experimentally.The experimental program was carried out in the laboratory with an electromagnetic stress-wave generator. During each test, impact velocity was measured at the base of the specimen by means of a contacting wire system. Also, pressure was measured at the opposite end with a piezo-resistive pressure transducer with a flat response from below 0.5 to above 100 kHz.Densities of snow samples in the range from 200 to 500 kg m−3were tested. Impact velocities at the base were varied from 20 to as high as 100 rns−1. Propagation distances (specimen lengths) were varied from 2 to 5 cm. Also, for each test, the free water moisture content in the test specimen was carefully measured so that the effect of this property could be evaluated. The test results are reported and the wave attenuation rates are characterized in terms of the parameters discussed above. In addition, these results are compared to test results for dry snow.Finally, wave propagation theory is used to evaluate the material tangent modulus. The theory is also used to calculate particle velocity and density increases produced by the shock waves. The results are compared to those obtained earlier for dry snow.