scholarly journals FUNDAMENTAL STUDY ON THE EVALUATION OF SNOW LOAD : Part 1 Average density of snow cover

1982 ◽  
Vol 319 (0) ◽  
pp. 32-38
Author(s):  
HIROSHI MAEDA
Keyword(s):  
Snow Cover ◽  
Average Density ◽  
Fundamental Study ◽  
Snow Load

scholarly journals Snow instability evaluation: calculating the skier-induced stress in a multi-layered snowpack

2016 ◽  
Vol 16 (3) ◽  
pp. 775-788 ◽  
Author(s):  
Fabiano Monti ◽  
Johan Gaume ◽  
Alec van Herwijnen ◽  
Jürg Schweizer
Keyword(s):  
Crack Propagation ◽  
Snow Cover ◽  
Stability Index ◽  
Elastic Half Space ◽  
Average Density ◽  
Additional Stress ◽  
New Approach ◽  
Weak Layer ◽  
Failure Initiation ◽  
Induced Stress

Abstract. The process of dry-snow slab avalanche formation can be divided into two phases: failure initiation and crack propagation. Several approaches tried to quantify slab avalanche release probability in terms of failure initiation based on shear stress and strength. Though it is known that both the properties of the weak layer and the slab play a major role in avalanche release, most previous approaches only considered slab properties in terms of slab depth, average density and skier penetration. For example, for the skier stability index, the additional stress (e.g. due to a skier) at the depth of the weak layer is calculated by assuming that the snow cover can be considered a semi-infinite, elastic, half-space. We suggest a new approach based on a simplification of the multi-layered elasticity theory in order to easily compute the additional stress due to a skier at the depth of the weak layer, taking into account the layering of the snow slab and the substratum. We first tested the proposed approach on simplified snow profiles, then on manually observed snow profiles including a stability test and, finally, on simulated snow profiles. Our simple approach reproduced the additional stress obtained by finite element simulations for the simplified profiles well – except that the sequence of layering in the slab cannot be replicated. Once implemented into the classical skier stability index and applied to manually observed snow profiles classified into different stability classes, the classification accuracy improved with the new approach. Finally, we implemented the refined skier stability index into the 1–D snow cover model SNOWPACK. The two study cases presented in this paper showed promising results even though further verification is still needed. In the future, we intend to implement the proposed approach for describing skier-induced stress within a multi-layered snowpack into more complex models which take into account not only failure initiation but also crack propagation.

scholarly journals Snow loads in a changing climate: new risks?

2008 ◽  
Vol 8 (1) ◽  
pp. 1-8 ◽  
Author(s):  
U. Strasser
Keyword(s):  
Snow Cover ◽  
Freezing Point ◽  
Warning System ◽  
Winter Precipitation ◽  
Snow Load ◽  
Time Period ◽  
Sudden Rise ◽  
Trigger Event ◽  
Snow Loads ◽  
Modelling Data

Abstract. In January/February 2006, heavy snowfalls in Bavaria (Germany) lead to a series of infrastructural damage of catastrophic nature. Since on many collapsed roofs the total snow load was not exceptional, serious engineering deficiencies in roof construction and a sudden rise in the total snow load were considered to be the trigger of the events. An analysis of the then meteorological conditions reveals, that the early winter of 2005/2006 was characterised by an exceptional continuous snow cover, temperatures remained around the freezing point and no significant snowmelt was evident. The frequent freezing/thawing cycles were followed by a general compaction of the snow load. This resulted in a re-distribution and a new concentration of the snow load on specific locations on roofs. With respect to climate change, the question arises as to whether the risks relating to snow loads will increase. The future probability of a continuous snow cover occurrence with frequent freezing/thawing cycles will probably decline due to predicted higher temperatures. However, where temperatures remain low, an increase in winter precipitation will result in increased snow loads. Furthermore, the variability of extremes is predicted to increase. If heavy snowfall events are more frequent, the risk of a trigger event will likely increase. Finally, an attempt will be made here in this paper to outline a concept for an operational warning system for the Bavarian region. This system envisages to predict the development and risk of critical snow loads for a 3-day time period, utilising a combination of climate and snow modelling data and using this together with a snow pillow device (located on roofs) and the results of which.

scholarly journals Sensitivity of the results of modeling of seasonal ground freezing to selection of parameterization of the snow cover thermal conductivity

2019 ◽  
Vol 59 (1) ◽  
pp. 67-80 ◽  
Author(s):  
S. P. Pozdniakov ◽  
S. O. Grinevskyi ◽  
E. A. Dedulina ◽  
E. S. Koreko
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Snow Cover ◽  
Soil Profile ◽  
Average Density ◽  
Temperature Correction ◽  
Freezing And Thawing ◽  
Coupled Models ◽  
Seasonal Freezing ◽  
Effective Medium Model

The relationship between the results of calculations of the dynamics of the temperature regime of the in freezing and thawing soil profile with the heating effect of the snow cover is considered. To analyze this connection, two coupled models are used: the model of formation and degradation of snow cover in winter and the model of heat transfer and soil moisture transport in underlying vadoze zone profile. Parametrization of the influence of the snow cover, which at each calculated moment of time has the current average density and depth, on the dynamics of the temperatures of the soil profile is due to the use of its specific thermal resistance, which depends on its current depth and the thermal conductivity coefficient. The coefficient of thermal conductivity of the snow cover is related with its density using six different published empirical relationships. Modeling of heat transfer in freezing and thawing soil is carried out on the example of the field site for monitoring the thermal regime located on the territory of the Zvenigorod Biological Station of Moscow State University. It is shown that the well-known relationships give similar curves for the dynamics of the depth of seasonal freezing, including the degradation of the seasonal freezing layer in the spring period, with the same dynamics of the snow cover. However, the maximum penetration depth of the zero isotherm differs significantly for different snow conductivity-snow density relationships. The tested six relationships were divided into three groups. Minimal freezing is provided by the Sturm model and the effective medium model. The average and rather poorly differentiating freezing from each other is given by the Pavlov, Osokin et al. and Jordan relationships. The greatest value of the freezing depth is obtained with using Pavlov’s relationship with a temperature correction. 

scholarly journals Snow on two-level flat roofs — measured vs. 1990 NBC loads

1992 ◽  
Vol 19 (1) ◽  
pp. 59-67 ◽  
Author(s):  
Donald A. Taylor
Keyword(s):  
Average Density ◽  
Research Needs ◽  
Snow Density ◽  
Limit States ◽  
Snow Load ◽  
Load Factors ◽  
Multi Level ◽  
Snow Loads ◽  
Upper Level ◽  
Flat Roofs

Between 1967 and 1982, depths and specific gravities of snow were recorded on 44 single- and multi-level flat-roofed buildings between Halifax and Edmonton. The average density of snow in the drifts where the roofs change elevation was about 3.0 kN/m3, the value used consequently in the 1990 National Building Code of Canada (NBC). This is some 25% higher than the value used in the 1985 NBC. Data on drift geometry and maximum loads in the drifts are presented and compared with provisions in the 1990 NBC. As well, the paper presents measured values of average and maximum roof-to-ground load ratios for upper level roofs and for lower roofs away from the drifts. These compare favourably with those recommended in the 1985 and 1990 NBC. The statistical variabilities of snow loads and densities are given, since these are required to establish load factors used for limit states design in the NBC. Further research needs are identified. Key words: snow loads, snow drifts, uniform snow, flat roofs, snow density, snow load variability, snow load survey.

scholarly journals Mapping the Characteristics of Snow Cover in Belarus

2020 ◽  
Vol 212 ◽  
pp. 01013
Author(s):  
Aleh Meshyk ◽  
Viktoryia Marozava ◽  
Maryna Barushka
Keyword(s):  
Snow Cover ◽  
Snow Load ◽  
Load Limits

The paper substantiates a necessity to create maps of snow cover characteristics in Belarus. The designed maps can be used by engineers to forecast spring floods on the rivers of Belarus and to assign snow load limits imposed on buildings and structures.

scholarly journals A FUNDAMENTAL STUDY ON SNOW LOAD EVALUATION CONSIDERING UNCAUGHT RAINFALL BY SURVEY OF CONDITIONS AT WEATHER OBSERVATION STATIONS

2018 ◽  
Vol 24 (56) ◽  
pp. 35-40
Author(s):  
Hajime NAKAJIMA ◽  
Satoshi KOMODA ◽  
Shigeto FUJII ◽  
Yuichiro ISHINABE
Keyword(s):  
Fundamental Study ◽  
Snow Load ◽  
Load Evaluation ◽  
Weather Observation

scholarly journals Measurement of water equivalent, average density and height of layered snow cover using UWB electromagnetic pulses.

2021 ◽  
Author(s):  
K.V. Muzalevskiy ◽  
Keyword(s):  
Snow Cover ◽  
Snow Water Equivalent ◽  
Amplitude Ratio ◽  
Farming Systems ◽  
Average Density ◽  
Frozen Soil ◽  
Ultra Wideband ◽  
Coefficient Of Determination ◽  
Test Plot ◽  
Agricultural Field

Abstract. In this work, the processes of interaction of ultra-wideband (UWB) pulses with the duration of 0.47 ns with layered dry snow cover are theoretically investigated. The layered structure of the snow cover was modeled on the basis of experimental data on the height and density profile of the snow cover, which were measured in field on the test plot of an agricultural field in the area of the village. Minino, Krasnoyarsk Territory from November 12, 2020 to March 21, 2021. It is shown that the snow water equivalent (SWE) can be estimated from the time delay of the pulse reflected from the snow-soil interface with the coefficient of determination (R2) R2 = 0.98 and the root-mean-square error (RMSE) RMSE = 5.6 mm in the case of thickness from 4-6 to 39cm and an average density from 0.21 to 0.37 g/cm3 of snow cover. It is shown that the average density of snow cover linearly depends on the amplitude ratio of impulses reflected from the boundaries, snow-soil and air-snow (R2 = 0.55, RMSE = 0.04 g/cm3). The established dependencies make it possible to estimate the height of the snow cover with R2 = 0.95, RMSE = 2.9 cm. The accuracy of the proposed method for measuring SWE, average density and height of snow cover should be further investigated depending on variations in temperature, moisture, density, and texture of frozen soil, as well as under different moisturized conditions of snow. The obtained results are particular relevance in connection with the possibility of implementing this remote sensing method from the UAV, which opens up the prospects for creating a technology for UWB radar mapping of the main characteristics of the snow cover for use in precision farming systems.

scholarly journals Expected Snow Loads on Structures from Incomplete Hydrological Data

1977 ◽  
Vol 19 (81) ◽  
pp. 185-195 ◽  
Author(s):  
J. Martinec
Keyword(s):  
Snow Cover ◽  
Frequency Analysis ◽  
Building Code ◽  
Return Periods ◽  
Snow Load ◽  
Hydrological Data ◽  
Regional Effects ◽  
Direct Measurements ◽  
Snow Loads

Abstract An assessment of snow loads in Switzerland was required for a revision of the building code. Settling curves of snow are used to compute water equivalents of snow if direct measurements are not available. Based on a frequency analysis, relations between the snow load and the altitude are given for various return periods. Problems of regional effects and of converting the snow-cover data to roof loads are outlined.

scholarly journals The remote sensing of snow water equivalent using broadband electromagnetic pulses from an UAV board.

2021 ◽  
Author(s):  
K.V. Muzalevskiy ◽  
Keyword(s):  
Remote Sensing ◽  
Snow Cover ◽  
Snow Water Equivalent ◽  
Test Site ◽  
Average Density ◽  
Information Support ◽  
Agricultural Field ◽  
Electromagnetic Pulses ◽  
Sensing Technology ◽  
Snow Water

In this paper the possibility of snow cover remote sensing from an unmanned aerial vehicle-quadrocopter (UAV) with using a broadband pulse of 1.05 ns duration was investigated on the agricultural field near Minino village, Krasnoyarsk Territory from November 23, 2020 to March 4, 2021. A log-periodic antenna (from 1.36 GHz to 4.89 GHz bandwidth) and a compact vector network analyzer CABAN R60 (LLC Planar, Chelyabinsk) were used to generate, emit and receive broadband pulses. It is shown that both ground-based and remote sensing from the UAV, the time delays between pulses reflected from the air-snow and snow-soil interface linearly depend on the snow water equivalent, measured at the test site. The slope of these linear dependences is determined by the average density of the snow cover. The obtained experimental results show the promising of development of remote sensing technology for radar mapping of the main characteristics of the snow cover from UAV, which can supplement the information support of existing systems used in precision farming.

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