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Volume 39 (1977)
- Issue 4 Pages 1-
- Issue 3 Pages 109-
- Issue 2 Pages 53-
- Issue 1 Pages 1-
- Issue Special Pages 1･･･
Volume 39, Issue 2
Displaying 1-3 of 3 articles from this issue
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Tsutomu TAKASHI, Takahiro OHRAI, Hideo YAMAMOTO1977 Volume 39 Issue 2 Pages 53-64
Published: June 30, 1977
Released on J-STAGE: January 22, 2010
JOURNAL FREE ACCESSWhen the soft soil freezes accompanying with the water suction, the effective stress increases with the lowering of pore water pressure that takes place near the freezing front, and thereby the unfrozen soil adjacent to it is subjected to a fairly strong dewatering consolidation. In this paper pore water pressure distribution in front of unidirectional freezing front penetrating at a constant rate is analyzed theoretically, and it is found that the lowering of pore water pressure is larger than expected. Therefore the lowering of the pressure may explain a soft soil subsidence after thawing and sludge dewatering by freezing. Influence region of dewatering consolidation, δs, is given by Cυ/U, and transitional time attaining to a steady state, τt, is given by A·Cυ/U2. Here Cυ is coefficient of consolidation, U is frost penetration rate and A is a positive constant.
In the case of soil which is relatively low in the degree of consolidation, the freezing expansion and dewatering consolidation take place simultaneously, and at far from δs in unfrozen soil the result of their mutually subtracted effect is observed as the amount of frost heave. Then, frost heave ratio, ξ, is given approximately by ξ0+nfΓ. Here ξ0is a characteristic constant of the soil, nf is free water content of soil at freezing temperature andΓ is nondimensional volumetric expansion ratio of water at freezing ≅ 0. 09.View full abstractDownload PDF (1835K) -
Iwao TSUCHIYA1977 Volume 39 Issue 2 Pages 65-76
Published: June 30, 1977
Released on J-STAGE: September 04, 2009
JOURNAL FREE ACCESSThere are several drift type perennial snow covers at niches of 1300-1900m above sea level on the southern slope of Mt. Chokai (2237 m, N 39°06, E 140°03') where are lee side places of the winter northwest monsoon. These snow covers turn to ice packs in a year after the snowfall season since the very large depth of snow cover.
During the survey of 1972-1976, the Kai-gata (shell shape) Glacieret at the height of 1400 m, one of these perennial snow (and ice) covers, showed the ablation depth of about 30 m/year and the notable interannual mass variation. In the 1974 spring airborne photogrammetry, the maximum depth of snow cover was estimated at > 45 m after the heavy snowfalls of 1973/74 winter, and the mass of ice in the 1974 fall was over 20 m depth, then the glacieret flowed at a rate of about 20 cm/day during the 1975 summer season as a small niche type glacier.
In the progress of the year-to-year variation of the Kai-gata Glacieret, there are several cases of the observation of the annual boundary layer, the survey of the crystal structure of the boundary, the disappearance of the one year snow cover and the key layer by the 1974 spring eruption of the Mt. Chokai, and the ablation rate of several meter per year at the bottom of the Kai-gata Glacieret is considered.View full abstractDownload PDF (18843K) -
Masami KITAMURA, Masaaki IMANAGA1977 Volume 39 Issue 2 Pages 77-83
Published: June 30, 1977
Released on J-STAGE: September 04, 2009
JOURNAL FREE ACCESSIn order to study the conditions of the tree damage by snow in the heavy-snow area, 1055 trees planted in 1959 on the stand of 0.52 ha have been observed from 1965 to 1975. During the observation period 580 trees had been heavily damaged by snow. In addition, some suppressed trees were cut. Until 1975 only 449 trees remained without heavy damage. Among them, however, some trees slightly damaged at their top parts. It is recognized that the damage is especially severe in the heavy snow year and the damaged trees mainly distribute in the valley and on the steep slope.View full abstractDownload PDF (752K)
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