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Volume 40 (1999 - 200･･･
- Issue 6 Pages 333-
- Issue 5 Pages 260-
- Issue 4 Pages 196-
- Issue 3 Pages 124-
- Issue 2 Pages 60-
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Volume 40, Issue 5
Displaying 1-7 of 7 articles from this issue
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Kenzo KIHO, Takahiro OYAMA, Yasunori MAHARA1999 Volume 40 Issue 5 Pages 260-269
Published: December 10, 1999
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSRecently, the Tertiary sedimentary rock has been being watched as a host rock of the space utilization for the deep underground. In order to estimate a geochemical feature of the underground water in the rock mass, an extraction and analysis of the pore water in the rock is very important method. From this view point, we produced a new apparatus for extracting the pore water in the soft rock, and we applied it to extract the pore water of the core sample which was taken from a deep drill hole.
Before analyzing the pore water, the evaluation of the drilling water effect to the core sample was performed, and its effect was estimated 2 to 12% in sandy rocks at the upper depth, and 0% in mudstone at the lower depth. From the analytical results of the pore water of each depth, it is recognized that the deep seated underground water is rich in sodium and bicarbonate, and the deeper water is lighter in oxygen isotope. It is supposed that the pore water chemistry results from the calcite dissolution and ion exchange of the clay minerals, and the oxygen and hydrogen isotopes in the pore water can be explained as a result of the fractionation during the alteration of plagioclase to kaolinite.View full abstractDownload PDF (1701K) -
Hideo KIYA, Takehiro OHTA1999 Volume 40 Issue 5 Pages 270-280
Published: December 10, 1999
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSOne of the most important problems of tunnel construction is the face collapse and wash-out due to water inflow into the tunnel. In our past research, we performed a fundamental experiment on the relation between the strength of ground and water seepage tests with a simulated tunnel face to measure the critical hydraulic gradient when the test sample collapses.
In the present study, we sampled the soil at a position where the tunnel face actually collapsed, tested it by applying the above method, compared the test results with the actual conditions of the tunnel face and discussed the validity of the method for evaluation of tunnel face conditions. Test results are as follows.
(1) Tests with undisturbed samples well explain the actual condition at the tunnel excavation site.
(2) In the tests with disturbed samples, the fundamental relation between the hydraulic gradient and the relative density of soil is represent at high accuracy by an exponential regression curve which we call “the characteristic curve of seepage failure” with the fine grain content as a parameter. We can evaluate the stability of tunnel face in relative terms by comparing characteristic curve of difficult soil samples.
From the above findings and a study of the conditions for application, we conclude that this method is effectively applicable to the evaluation of the stability of sandy soil tunnel face.View full abstractDownload PDF (2444K) -
Sedimentary Rocks, Miocene Onnagawa Formation, Oga PeninsulaShin-ichi KIMURA, Naotatsu SHIKAZONO, Masato NOHARA, Shuhei IWAI1999 Volume 40 Issue 5 Pages 281-294
Published: December 10, 1999
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSWe examined mineralogical and geochemical studies of weathered shale and siliceous shale, Miocene Onnagawa Formation, Oga peninsula, to understand the migration of trace and rare earth elements during the chemical weathering of sedimentary rocks under oxic environment.
Pyrite is completely decomposed and ferrous iron hydroxide formed in the weathered sedimentary rocks. P, Mn, Co, Ni, Cu, Mo, Pb, U and REEs contents of weathered rocks are quite different from those of parent rocks. The decrease ratios of P, V, Mo, Pb, U and REEs are small with the increasing of increase ratio of Fe2O3* in the weathered rocks. These mineralogical and geochemical variations suggest that dissolved trace and rare earth elements were reaccumulated in the weathered rock by adsorption onto ferrous iron hydroxides.
However, there is significant difference between in the elemental adsorption ratio of shale and siliceous shale. The adsorption ratios of elements onto ferrous iron hydroxides of shale are generally lower than those of siliceous shale. Based on mineral composition of shale and siliceous shale, we conclude that the difference between in the adsorption ratios of shale and siliceous shale was caused by the changes of dissolved elements species and surface charge of ferrous iron hydroxide, because the pH condition for the weathering of pyrite-rich shale was more acidic than that of pyrite-poor siliceous shale.View full abstractDownload PDF (4711K) -
Makoto IMANO, Manabu TSUBOMATU, Yoshihisa HOSHINO1999 Volume 40 Issue 5 Pages 295-298
Published: December 10, 1999
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSMoisture content in the soil is generally measured using a drying oven or neutron moisture meter. However, the former method ever requieres a lot of time if a sample is large in quantity. On the other hand, the latter is not only controlled under low, but is also supplied with stable energy for measuring from nature.
We produced the instrument using muon, a kind of natural cosmic ray, for measuring moisture content by way of experiment. We measured the moisture content in the soil with an 2.8% of error from the value using drying oven. Therefore, this method is likely effective in measuring moisture content in the soil.View full abstractDownload PDF (757K) -
Weiren LIN, Manabu TAKAHASHI, Xiaochun LI, Kiyofumi SUZUKI1999 Volume 40 Issue 5 Pages 299-305
Published: December 10, 1999
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSIt is clear that the permeability of a hydraulically tight rock can be measured accurately only when the side clearance flow between the specimen surface and the jacket material is completely prevented. To verify the effect of jacketing method on permeability measurement, specimens of Shirahama sandstone covered with three different methods were tested by means of the transient pulse technique. The results showed that when a specimen is jacketed with the shrinkable tube only, the side clearance flow may occur and cause overestimation of the permeability. This clearance flow, however, can be prevented by spreading a layer of low-viscosity silicone rubber on the side surfaces of the specimen and end pieces before covering the shrinkable tube.
The equivalent cylindrical capillary radii of the pathway of the side clearance flow under the tested conditions were then quantitatively evaluated. The results illustrated that even when a equivalent cylindrical capillary radius is thin as 0.01mm, its influence on the permeability measurements can be notable. In addition, transmission of the confining pressure from the pressure medium in the vessel to rock specimen was discussed by the theory of elasticity which support that if the young's modulus of a rock specimen is equal to or larger than that of the jacket material, the pressure in the vessel can be fully transmitted to the rock specimen through the jacket material.View full abstractDownload PDF (1362K) -
Hideki INAGAKI1999 Volume 40 Issue 5 Pages 306-315
Published: December 10, 1999
Released on J-STAGE: March 25, 2010
JOURNAL FREE ACCESSMany slope surface failures occurred in the southern part of Fukushima prefecture and the northern part of Tochigi prefecture caused by heavy rainfall of typhoon 9804 on August 1998.
These slope surface failures are characterized as follows.
Many slope failures are located on steep slope along erosion front or below the erosion front, concentrating surface water and underground water.
Thickness of slope failures is very thin as less 1m and the sliding mass contains many roots of plants. However, pyroclastic rock as underlying basement rocks do not contains roots of plants caused by no existence of crack in itself.
These slope failure are named slope failure along roots of plants by author. This paper describes features of the slope failure along roots of plants and reinforcing effects of roots of plants in soil against slope failure.View full abstractDownload PDF (2427K) -
Study Group, Chugoku-Shikoku Branch, Japan Society of Engineering Geology[in Japanese], [in Japanese], [in Japanese], [in Japanese], [in Japane ...1999 Volume 40 Issue 5 Pages 316-321
Published: December 10, 1999
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSSlope failure disasters occurred due to a continuous heavy rainfall on June 29, 1999, causing the death of 31 habitants of Hiroshima Prefecture. Such disasters were mostly resulted from slope collapse and debris flow at living areas adjacent to steep slopes where weathered granite exists in layers.
The collapse layers were made up of highly permeable talus deposits and the so-called Masa (weathered granite). At the base of a failure slope, soft rocks were mostly exposed. It is presumed that a concentrated heavy rain, following a week long continuous rainfall, saturated the highly permeable upper ground layers at a tremendous speed and then lead to collapse of slopes.
The occurrence of these slope-collapse disasters was considered to be due to non-uniformity of the ground's permeability and strength as a primary cause and the rainfall pattern as an occasional cause.View full abstractDownload PDF (3202K)
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