Fersh snow is caracterized by a friable grain packing with a coordination number less than 3, small values of elastic mave velocities (< 100 m/s), moduli of elasticity(104 - 105 Pa) and strength (<: 102 Pa ). The changes of a snow structure during his desification and diagenesis lead to a considerable increase of these caracteristics which does not be statisfactory described by one function that will be universal for the whole density range.
Analysis of experimental data on the elastic mave velocities and dynamic moduli permit to distinguish the folowing snow density subranges: 30-160, 160-330, 330-550 kg/m3 within of which the changes of elastic properties occur with different intensity and can be described by monotonic functions. The critical (limiting) densities 160, 330 and 550 kg/m3 are caracterized the replacements of the structure-textural trancformation prevelling mechanisms.
Both elastic moduli and strength of a dray coherent snow basically depend on the same structural parameters: a coordination number of structure, an average distance between centers of a contacting grains, a ratio of the average linear grain size and intergrain contact area size. During a snow densification the values of these parameters are changed regulary and, for example, according to our estimations the above mentioned critical densities correspond to coordination numbers 3, 4 and 6. The tensile strength values evaluated from structural parameters and elastic moduli in the whole snow density range are in a good agreement with the experimental data. For the citical densities the strength values were found: 4 * 102, 6 * 103 and 1,2 * 105 Pa. The regularities obtained for dinamic elastic moduli and tensile strength of snow within three above mentioned density subranges are presented and discussed in the paper.
Prof. Anatoly D. Frolov United Sientific Council on Earth Cryology Russian Academy of Sciences Apt 128, Leninsky Prospect 64, Moscow: 117296, Russia Telephone: (095) 930-2634 Fax: (095) 253-1192 E-mail: kvb@kvb.msk.ru (For A.Frolov) Vladimir N. Golubev Geographical Department Moscow State University Moscow, Russia