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Volume 25 (1984)
- Issue 4 Pages 158-
- Issue 3 Pages 103-
- Issue 2 Pages 47-
- Issue 1 Pages 1-
Volume 25, Issue 3
Displaying 1-5 of 5 articles from this issue
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Kuniaki SATO, Yasuo SASAKI1984 Volume 25 Issue 3 Pages 103-110
Published: September 30, 1984
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSWhen we deal with the solute dispersion problems in rock ground, the evaluation of dispersion coefficient becomes important as well as the determination of hydraulic parameters like the permeability. This paper presents how to determine the dispersion coefficient of rocks in a laboratory, and the values of dispersion coefficients for many kinds of rocks collected from different locations in this country were determined by using a newly designed apparatus.
The results in this study are summarized as follows:
1) The utility of apparatus proposed in this study was confirmed by the experimental results.
2) The rock dispersion coefficients were 4.75×10-6-4.80×10-9m2/s for all rock samples.
3) The dispersion coefficient increases with increasing Reynolds number.View full abstractDownload PDF (1643K) -
Takeshi ENDO, Motomu ISHII1984 Volume 25 Issue 3 Pages 111-120
Published: September 30, 1984
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSThe plain area in the east part of Tokyo, Musashino Terrace and Shitamachi Lowland, is underlain by Quaternary thick sediments. These sediments are divided stratigraphically into two groups, the lower is the Kitatama Formation and the upper the Tokyo Formation. The general strike of the Formations tends NNWSSE with a very low dip to the northeast. Upper layers of the Tokyo Formation are mainly composed of silt, sand and gravel, forming the aquifer system of artesian groundwater. According to the distribution of Tritium ratio in the groundwater, which of Musashino Terrace has mainly supplied from the surface water of the Tama River.
Withdrawal groundwater from these aquifers has caused the lowering of groundwater level and the land subsidence all over the plain. The lowering of groundwater level and the land subsidence, however, which have continued half a century, rapidly taken favorable turns during recent about ten years due to restrictions of groundwater withdrawal.
Recovering of groundwater level has not only brought about the favorable turn of the land subsidence, but also decreasing the spout of oxygen deficient air through water wells and the cracks of basements at the time of air pressure change or pnuematic work in the underground. It also has advanced the secondary storage of natural water soluble gas, which has reserved originally in the deep layers, the Kazusa Group, into gravel layers beneath the Yurakucho Formation.View full abstractDownload PDF (2040K) -
Takeyasu SUZUKI1984 Volume 25 Issue 3 Pages 121-132
Published: September 30, 1984
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSIt is a well known fact that excess pore pressure builds up when the soil is subjected to cyclic loading. In the case of clays, the dissipation of pore pressure causes long term settlement. Dynamic simple shear test was carried out using different types of clays. Measurement was made of the residual excess pore pressure and volumetric change after cyclic shear. Then, drainage mechanism is discussed in details. The settlement or axial strain caused by the drainage of pore water can be expressed by a hyperbolic function of pore pressure ratio. This relation is not influenced by the amplitude and speed of cyclic shear stress. In addition, it was found that the drainage mechanism of normally consolidated clays after cyclic shear is closely related to the compressive coefficient Cc and swelling coefficient Cs which are obtained by a consolidation test. Finally, the settlement simulation was excuted in order to apply this research to the field, involving discussions on the effect of over consolidation ratio.View full abstractDownload PDF (1692K) -
Shinji AKUTAGAWA, Hidehiko KAZAMA1984 Volume 25 Issue 3 Pages 132-140
Published: September 30, 1984
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSSurface slip on slopes of slightly consolidated sand beds is considered to be one of the important types of failures which occurs most frequently on the natural slopes.
In this paper, the authors described at first, an example of detailed field inspection data on the failures arose in Narita sand group (Pleistocene) and they concluded that the slip plain is situated in the zone of loosened sand laid under the sand zone which is much loosened but reinforced by the roots of plants. They added the field observation of loosening speed on the cutted slopes in similar sand beds and the results of laboratory experiments: strength reduction accompanied with increment of water contents and sharp change of cohesion when void ratio excess 1.0-1.2.
The authors also concidered on the microscopic structure model of these semi-consolidated sand and explained about the process of weaking and surface slip by the microscopic process of loosening.View full abstractDownload PDF (1662K) -
Haruo YAMAZAKI, Eikichi TSUKUDA, Kiyohide MIZUNO1984 Volume 25 Issue 3 Pages 141-145_1
Published: September 30, 1984
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSDownload PDF (5169K)
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