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The observations of the snow cover and its sliding down on the galvanized iron roofs

1977; Japanese Society of Snow and Ice; Volume: 39; Issue: 1 Linguagem: Inglês

10.5331/seppyo.39.7

1883-6267

Shinnosuke Miyauchi,

Urban and spatial planning

Recently, many houses built in heavy snow districts have been roofed with galvanized iron sheets which have less friction with snow cover on them. It is convenient that the snow cover on the roofs falls down naturally but its sudden falling is very dangerous. In spite of a wide use of the roof, the condition of the sliding down of the snow on the galvanized iron roof have not as yet been fully investigated.Since 1974, the snow cover on galvanized iron roofs of 76 houses and its sliding down have been observed in Nagaoka city, Tokamachi city and Tsunan town, Niigata prefecture.Following results were obtained from the observation.(1) A large amount of snow was accumulated on the roof, during heavy snow periods from January 9, 1975 to January 13 and from January 18, 1976 to January 24 in the Niigata district. The amount of the snow did not depend upon the gradient of the roof and this leads us to the conclusion that the freezing between the roof surface and snow cover causes such a large amount of snow accumulation on the roof.(2) The sudden sliding of the snow cover occured when the air temperature rose after the heavy snows. In a certain case, the snow fell 6 m far from a house.(3) The coefficient of the friction between the roof surface and the snow cover was estimated from the sudden falling down of the snow cover occured in Tokamachi city and its value is 0.1.