All issues
Volume 21 (1980)
- Issue 4 Pages 181-
- Issue 3 Pages 119-
- Issue 2 Pages 51-
- Issue 1 Pages 1-
Volume 21, Issue 2
Displaying 1-6 of 6 articles from this issue
- |<
- <
- 1
- >
- >|
-
Yoshiroh HAYASHIDA1980 Volume 21 Issue 2 Pages 51-59
Published: June 30, 1980
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSThe ground is always vibrating from the natural and artificial disturbances, it is called a microtremor which measures a few microns in amplitude.
It has been clarified by engineering seismologists that there was a very closed relationship between the earthquake damages and the subsurface structures, and that when the ground was visited by earthquake shocks, the predominant period of the earthquake motion nearly coincides with one of the frequent periods of the microtremor at the respective places.
From the multireflection theory, the microtremor comprises the wave motions magnified by complex multireflection and transmission of the wave within the surface soft layer. Therefore we can estimate the subsurface structures by studying the microtremor.
In this paper, the author reports the results of some theoretical and practical studies on the sounding with the microtremor data and discusses them.View full abstractDownload PDF (1079K) -
Kunio WATANABE, Yosinobu HOSHINO1980 Volume 21 Issue 2 Pages 60-70
Published: June 30, 1980
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSThe open-cracks in large rock mass play an important role in flowing ground water. The main purpose of this paper is to present the method used to estimate the permeability coefficient of natural open-crack from the distribution of its opening width.
We studied on this problem by following procedures.
(1) The numerical method to describe the approximate flow behaviors in open crack was introduced on the basis of Poiseuille law.
(2) Some permeability coefficients of natural open-cracks were calculated from these distributions of opening width by this method.
(3) These calculated values were compared with the values measured by the permeability test apparatus respectively.
As the result, it was found that the permeability coefficient of natural open-crack can be well estimated by this numerical method.View full abstractDownload PDF (1701K) -
Hideo KASAI1980 Volume 21 Issue 2 Pages 71-79
Published: June 30, 1980
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSIn August, 1979, a large-scale mudflow occurred at Hora valley near Tochio area of Kamitakara village (Gifu Pref.), then the area suffered from severe disaster.
In this report, inferred causes and conditions of occurrence of mudflow based on the field investigations at the stricken area are described.
At first, geological constitution and their features of Tochio area were reviewed. Secondary, the author attempted to conjecture conditions of running down of the mudflow based on the detail observations of the mudflow deposit. At last, limitation of rainfall condition on occurrence of mudflow was estimated from hydrological data and past record on the typical disaster at the area.
Results obtained from this investigation are as follows:
1) The debris which was produced by collapse of Nohi-rhyolite at the uppermost-reaches of the valley might run down taking deposit of the channel into the flow.
2) A part of the mudflow began to accumulate at the place where valley suddenly broaden, and remaining part of it run down further and accumulated at the lowermost-reaches in Tochio area.
3) Mean velocity of the mudflow was estimated as follows:
In the valley………6.0-6.5m/sec
At the place where valley suddenly broaden……… 4m/sec
At Tochio area………1.6-2.5m/sec
4) Critical precipitation for occurrence of mudflow at the valley was estimated. It is about 30 mm/hour for intensity of effective precipitation.View full abstractDownload PDF (2443K) -
An Application of Gravitational Method to the Survey of a Tectonic Basin in the HimalayasShigeo MORIBAYASHI, Yuji MARUO1980 Volume 21 Issue 2 Pages 80-87
Published: June 30, 1980
Released on J-STAGE: March 25, 2010
JOURNAL FREE ACCESSGravity survey was carried out to clarify the basement topography of the Kathmandu Valley which is filled with the Quaternary lacustrine sediments. A gravity anomaly map is produced from 112 gravity measurements within a major part of the Kathmandu Valley and a basement contour map is presented based on depth calculations along two sections.
The maximum depth of the basement is estimated to be a little more than 650m from the present surface. Two distinct troughs of basement are detected in the central part of the Valley. The troughs may be a part of fossil valleys of what Hagen (1968) proposed as the Proto-Bagmati River which supposedly had drained south-south-westerly across the Kathmandu Valley during the Plio-Pleistocene time.View full abstractDownload PDF (1106K) -
Yukio OHI1980 Volume 21 Issue 2 Pages 88-97
Published: June 30, 1980
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSThere exist some layers of earth, found principally in Japan's cities, which react with and absorb oxygen in the air, Workers have died of asphyxiation when excavating these strata.
An effective way of preventing this kind of accident is to check before operations begin whether or not the area has been analyzed for oxygen absorbing layers.
The reason for this phenomena lies in the chemical properties of the soil.
This report demonstrates that the presence or absence of oxygen absorption soil can be determined by following chemical tests on soil samples to be taken during geological surveys:
1. Test for redox potential
2. pH test
3. Detremination of oxygen absorption by the Buret method
4. Analysis of ferrous and sulfur ions
In addition, the report shows that in those cases where the taking of samples is difficult, analysis of the oxygen content of gas that escapes from the borehole during gas permeability testing is also effective.View full abstractDownload PDF (1531K) -
[in Japanese]1980 Volume 21 Issue 2 Pages 98-100
Published: June 30, 1980
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSDownload PDF (321K)
- |<
- <
- 1
- >
- >|