Wind tunnel investigation of snow accumulations on a single flat roof and a two-level flat roof using artificial snow Part 1: Field survey of snow accumulations on real buildings by aerial photogrammetry and eye-measurements

摘要

This paper focuses the relationship between the prevailing wind direction and the distribution of snow accumulations on a single flat roof and a two-level flat roof. On the roofs except the lower roof of two-level roof, the results by the aerial photogrammetry show that the scouring zone of roof snow formed in "fan shape" and "deformed heart shape", respectively, and the drift zone formed in several ridges around both sides of the scouring zone to the edges of the roof. The snow accumulations on roofs are likely to form due to cumulative effects of multiple snowstorms during a winter, nevertheless the results by the eye-measurements, more than thirty times through the winter, show that the roof snow accumulations have a tendency to preserve the constant pattern. On the lower roof of a two-level flat roof, the degree of unbalanced snow depth is smaller than that of upper roof and the mean value of snow depth was approximately equal to that of grand snow.