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Volume 48 (2007 - 200･･･
- Issue 6 Pages 285-
- Issue 5 Pages 232-
- Issue 4 Pages 162-
- Issue 3 Pages 116-
- Issue 2 Pages 66-
- Issue 1 Pages 2-
Volume 48, Issue 4
Displaying 1-6 of 6 articles from this issue
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Satoru KAWASAKI, Sang Ho CHO, Katsuhiko KANEKO2007 Volume 48 Issue 4 Pages 162-169
Published: October 10, 2007
Released on J-STAGE: March 26, 2010
JOURNAL FREE ACCESSIn general, rocks are oxidized and weathered when they are exposed to the surface of the earth by natural erosions or man-made excavations. As a consequence, the strength of rocks that suffered such weathering decreases in the end. Provided that a new method which can estimate weathering thickness of rocks nondestructively, simply and quantitatively in the fields is developed, it is expected that the method is useful for the practical fields such as engineering geology, geotechnical engineering and so forth.
In order to develop a new estimation method for weathering thickness of rocks like boring cores or relatively shallow weathering layers of outcropping rock masses, the authors produced four kinds of man-made weathering rocks modeled on natural weathering rocks. Then a series of Equotip rebound hardness tests was conducted by using man-made weathering rocks. Furthermore, an experimental investigation was carried out by taking notice of especially weathering thickness of man-made weathering rocks and the ratio of weathering layers to nonweathering layers in rebound hardness. In this paper, firstly the man-made weathering rock model by which weathering thickness of weathering rocks and shallow weathering layers of rock masses can be estimated is explained. Secondly, some investigation results of the method for producing weathering layers of man-made weathering rocks and homogeneity of produced weathering layers are reported. Lastly, a new method for estimating weathering thickness of man-made weathering rocks nondestructively, simply and quantitatively is suggested by using rebound hardness of man-made weathering rocks, weathering layers and nonweathering layers, respectively.View full abstractDownload PDF (2096K) -
Takahito KUROKI, Nozomi ISO, Kensuke GOTO2007 Volume 48 Issue 4 Pages 170-179
Published: October 10, 2007
Released on J-STAGE: March 26, 2010
JOURNAL FREE ACCESSA lot of slope failures occurred on sideslopes of the mountain at Dazaifu city, Fukuoka pref. due to the 2003 Kyushu heavy rainfalls. In this study, at the upper reaches of Hara River, we investigated a sideslope where two slope failures had occurred. Then we discussed three relationships between joints of basement rock and landforms, soil horizon and slope failure, and the degrees of soil creep estimated by deformation of trees and landforms. Three joint systems exist in the basement rock. We classified the sideslope into seven landforms, crest, deep sidehollow, shallow side-hollow, terrace of smooth slope, landslide scar of valley floor, cliff and convex break of slope. Thick soil overlies basement rock and is creeping from crest to valley floor. Many forms of the basement rock were also classified. They are valley, hollow and stairs affected by the joint systems, and two buried convex breaks of slope affected by climatic change. These breaks of slope do not always exist just under the convex breaks of slope on the surface. The strength of soil creep is larger where the level of basement rock drops suddenly and at the valley side of convex break of the surface than other locations. On the basement rock, the soil creep is small at the crest side and is large at the valley side of the buried convex break of slope in strength. The soil which arrives and stagnates in the valley makes the shallow side-hollow and terrace of smooth slope. The causes of the slope failures are presumed that the soil above weathered angular gravels or decomposed granite was saturated with water by the heavy rainfalls, and then the stability of the soil decreased.
The joint systems on the basement rock affect the forms of sideslope, forms of basement rock and landforms, and trends of soil creep at the area. Consequently, we propose to survey not only landforms but also soil, trees, and joint systems of basement rock for the available prediction of the area induced slope failure.View full abstractDownload PDF (3838K) -
Hisafumi ASAUE, Katsuaki KOIKE, Toru YOSHINAGA, Shinichi TAKAKURA2007 Volume 48 Issue 4 Pages 180-191
Published: October 10, 2007
Released on J-STAGE: March 26, 2010
JOURNAL FREE ACCESSSome recent large earthquakes in Japan occurred in the areas where past seismic activity of faults had not been recorded well. For this reason, clarifying deep geologic structures and physical properties becomes more and more important for understanding genetic mechanism of earthquakes. MT (magnetotelluric) survey is one of the useful geophysical prospecting methods to detect such deep structures. The purpose of this study is to elucidate a relationship between the deep fault structures detectable from the MT-resistivity and the hypocenter distributions of microearthquakes. The Futagawa-Hinagu faults zone, typical active faults in central Kyushu, southwest Japan, was selected as a test site. It has a specific geological setting because the two faults with different strikes and surrounding lithologies seem to be connected topographically. From the 2D-inversion analysis of the apparent resistivity and phase data, laterally large change of resistivity was detected below the aerophoto lineaments. Because the northern part of the Hinagu Fault is not accompanied with extensive and remarkable low resistivity anomaly contrary to the Futagawa Fault, its damage zone is considered to be small. The low anomaly zones along the fault are limited to the southern part, which may result from the intersection between the fault and the Usuki-Yatsushiro Tectonic Line. It is noteworthy therefore that the fault structure, mechanical property, and regional stress field may be largely different between the Futagawa and Hinagu faults regardless of their adjacency. Considering the spatial density of the hypocenter distributions from 1995 to 2005, the Futagawa-Hinagu faults zone can be divided into four sub-zones I to IV toward the south. Based on the relationship between the MT deep resistivity and the hypocenter distributions, occurrence mechanisms of the earthquakes were discussed for each sub-zone. This examination clarified that the Futagawa and Hinagu faults are largely different in damage structure, mechanical property, and tectonic stress environment.View full abstractDownload PDF (7302K) -
[in Japanese], [in Japanese], [in Japanese], [in Japanese], [in Japane ...2007 Volume 48 Issue 4 Pages 192-202
Published: October 10, 2007
Released on J-STAGE: March 26, 2010
JOURNAL FREE ACCESSAt the offshore of Mid-Niigata Prefecture, a big earthquake of M6.8 occurred at 10: 13 on July 16th in 2007. The hypocenter of the main shock was 17km deep, and the maximum JMA seismic intensity 6+ was recorded over a wide coastal area. It gave serious damage to Kashiwazaki City, Kariwa Village, Izumozaki Town, Nagaoka City in Niigata Prefecture, and lizuna Town in Nagano Prefecture.
Japan Society of Engineering Geology (JSEG) started the urgent investigation from the next morning on July 17th headed by Dr. Nozaki, T. (vice president of Hokuriku Branch), and the preliminary report was uploaded to the web site of JSEG in a few days. Following this pre-investigation, JSEG organized investigative mission leaded by Prof. Yamagishi, H. (president of Hokuriku Branch) and supported by Debris Disaster Committee (Chairman: Prof. Chigira, M.) of the JSEG headquarters, and 13 volunteer members from Tokyo, Sapporo and Niigata were dispatched to the stricken area on August 3rd, when the maximum temperature had reached to 36°C. The temporary report by this mission was also uploaded to the web site of JESG.
On the basis of these field survey, particularly on the liquefaction and landslides both of which are typical seismic disasters, their situation and mechanisms are discussed in this paper.View full abstractDownload PDF (9105K) -
Kazushi MORI2007 Volume 48 Issue 4 Pages 203-206
Published: October 10, 2007
Released on J-STAGE: March 26, 2010
JOURNAL FREE ACCESSIn order to monitor small amount of seepage water appeared on downstream surface of earth dam, the author tried to use tippingbucket rain gauge successfully and concluded that the seepage water is derived from rainfall.View full abstractDownload PDF (784K) -
Hiroyuki OHNO, Mami OKU, Masafumi YOSHIDA, Toshiaki TSUTSUMI, Noriyuki ...2007 Volume 48 Issue 4 Pages 207-217
Published: October 10, 2007
Released on J-STAGE: March 26, 2010
JOURNAL FREE ACCESSRecently, not only in the advanced country but also in the developing country, the energy demand has increased a developing economy. It is impossible to fill all energy demand by a current fossil fuel. And, in the use of the fossil fuel, there is a problem on the environment to exhaust a lot of carbon dioxides which are the one of the factors of global warming. According to such a trend, the renewable energy as the photovoltaic and wind power generation is remarkable. The use of renewable energy is promoted in not only Europe and Japan, but also East Asia. The renewable energy is a regional distributed one, and its generation site is a compact scaled one. The regional distributed energy is produced and consumed in the community, so we need to suggest/consult considering to the characteristics of an individual region. Our geological engineers have grasped the characteristics at region, thus, we will also resolve the renewable energy problem at community.View full abstractDownload PDF (2445K)
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