Viscoelastic Properties of Snow and Sand

The frequency dependence of dynamic properties of the viscoelastic solids is studied based on the theory of linear viscoelasticity. The variation of dynamic moduli, viscosity, and the loss factor with frequency is explained by use of a relatively simple form of creep function. Employing a newly developed method of determining the dynamic response of materials, which enables one to obtain the results at any desired frequency, experimental results on snow and sand are obtained from steady state vibration over a large range of frequency. The experimental results agree with predictions of the theory of linear viscoelasticity, in which the distribution function of relaxation times is assumed equal to a constant divided by time between two time limits. It is shown that the theory developed is approximately obeyed by the test results on snow, but deviation from the theory is noted for the soil (Ottawa sand) used. In general, the dynamic moduli of both snow and soil increase slightly with frequency, the dynamic viscosity shows a decrease, and the loss factor remains, more or less, constant with frequency.