摘要:

This paper explores the computational problem of finding suitable numbers to use in a two-parameter model of snow avalanche dynamics. The two parameters are friction, μ, and a ratio of avalanche mass to drag,M/D. Given a path profile, and a maximum avalanche speed, then it is possible to compute unique values for u andM/D. If only the path profile and the stopping position are known, then it is possible to compute tables of pairs {μ,M/D} which can be tested as predictors of avalanche speeds. To generate these tables it is convenient to scaleM/Din multiples of the total vertical drop of the path. The computations were tested on 136 avalanche paths. Values of {μ,M/D} were stratified, and certain values were rejected as unrealistic.

ISSN:0008-3674    

DOI:10.1139/t81-011

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

A new technique for determining the volumetric unfrozen water content of frozen soils is reported, which uses time domain reflectometry (TDR) to measure the dielectric property. Using precise temperature control, the technique, which was developed previously by others for unfrozen soils, has been successfully applied to the measurement of unfrozen water contents of frozen soils. Curves of the dielectric property versus temperature show a close similarity to unfrozen water content curves, for a variety of soils. Results from experiments on ice–water mixtures and from combined TDR–dilatometry experiments on frozen soils suggest that an empirical relationship obtained by Topp, Davis, and Annan may be applicable to frozen media as well as unfrozen soils. Using this relationship, dielectric values were converted to unfrozen water content values, and the results agreed very closely with published data for similar soils, determined by other methods. For silt loams, agreement is typically within ± 1½% in volumetric water content, and for clays ± 3 %. Some of this difference is undoubtedly due to soil sample variations.

ISSN:0008-3674    

DOI:10.1139/t81-012

出版商:NRC Research Press    

年代:1981

数据来源: NRC

ISSN:0008-3674    

DOI:10.1139/t81-013

出版商:NRC Research Press    

年代:1981

数据来源: NRC

ISSN:0008-3674    

DOI:10.1139/t81-014

出版商:NRC Research Press    

年代:1981

数据来源: NRC

ISSN:0008-3674    

DOI:10.1139/t81-015

出版商:NRC Research Press    

年代:1981

数据来源: NRC

ISSN:0008-3674    

DOI:10.1139/t81-016

出版商:NRC Research Press    

年代:1981

数据来源: NRC

ISSN:0008-3674    

DOI:10.1139/t81-017

出版商:NRC Research Press    

年代:1981

数据来源: NRC

ISSN:0008-3674    

DOI:10.1139/t81-018

出版商:NRC Research Press    

年代:1981

数据来源: NRC

ISSN:0008-3674    

DOI:10.1139/t81-019

出版商:NRC Research Press    

年代:1981

数据来源: NRC

ISSN:0008-3674    

DOI:10.1139/t81-020

出版商:NRC Research Press    

年代:1981

数据来源: NRC