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Volume 40 (1999 - 200･･･
- Issue 6 Pages 333-
- Issue 5 Pages 260-
- Issue 4 Pages 196-
- Issue 3 Pages 124-
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Volume 40, Issue 6
Displaying 1-5 of 5 articles from this issue
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Slope Failure at San-in Railway Line between Nago and Nagato-OhiHiroshi OHSHIMA2000 Volume 40 Issue 6 Pages 333-339
Published: February 10, 2000
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSAbout twenty years ago a large slope failure happened at San-in Railway Line between Nago and Nagato-Ohi. There were 3 times of failure within 2 months. The author surveyed the field after the 2nd failure, and persisted that it had better to reopen the railway after removing earth and sand on the top of the slope. Although the compromise was unwilling, the author finally agreed to reopen the operation under the condition of carrying out the measurement of land distortion. However, 3rd failure happened after 2 weeks of reopening. Fortunately, the failure occurred in 40 minutes after from a train passed the area. It was the calamity with a possibility of becoming a large disaster by the case.
Why did it become such a situation? The author looks back on this disaster based on past data and memorandums, and takes a good reflection and gets some teachings for the future.View full abstractDownload PDF (2360K) -
Tatsutoshi KONDO2000 Volume 40 Issue 6 Pages 340-345
Published: February 10, 2000
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSIt is the most important target of geological site investigation to know if there would be any hazardous geological condition that might cause any increase of construction costs or long delay of construction duration.
With respect to the geological site investigations, it is obvious that identification of strata or stratigraphic correlation should be based on any scientific and geological methodology deductively. However, concerning geological surveying and drawing of geological structure surfaces, the location and extension of them should be estimated inductively based on geological events found at outcrops. Generally speaking, geological map as a solution of geological investigation might not be unique but has many solution candidates, since neither the quality nor numbers of the geological events satisfy the demands required to perform a complete geological map. As a result, the geologic maps might disagree with the actual structure in reality. The article consists of cralifying uncertainty of geological investigations which will be an important factor for the risk assessment and of proposing anew idea of geological investigation to reduce uncertainty.
The results of geological investigation should be used from the view point of the two aspects consisting of risk assessment with respect to geological structure and of site characterization to know the stability of tunnel ground.
The author describes that the inductive optimization method for geological mapping proposed will perform any effective consideration on tunnel design work, construction procedure as well, from the view point of risk assessment and site characterization.View full abstractDownload PDF (1378K) -
Keiji SHIRAI, Makoto NASU2000 Volume 40 Issue 6 Pages 346-354
Published: February 10, 2000
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSTunnels have sometimes caused to collapses, damages, deformations under construction or in operation.
To develope the measures for prevention of collapses, the authers have studied case histories for the past 40 years about the collapse examples under tunnel construction.
This paper describes that tunnel collapses have close relationship to the geological conditions, and they are liable to occur extremely in the geological boundaries between the different rockmasses.View full abstractDownload PDF (1446K) -
Takeshi TANAKA2000 Volume 40 Issue 6 Pages 355-366
Published: February 10, 2000
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSNatunal resources development starts from resources prospecting. Resources prospecting and engineering geological survey have so many common grounds as to their technique and object that the two fields should coopeate more closely. Among the techniques and knowledges employed in the engineering geological survey, the following may be of particular importance to resources prospecting, that is, seismic survey, numerical analysis of fault and fracture-systems based on rock mechanics, knowledge of rock mass classification and groundwater hydrology. On the contrary, application of the resources prospecting techniques to engineering geological survey may be most useful in surface and underground geological survey, geophysical and geochemical surveys, drilling, alteration survey etc. Because of the growing trend of larger scale civil engineering construction these days, undergroung geologic data such as those required in mining geology are becoming more and more important in engineering geological survey. In view of the close relationship between the above two fields of the applied geology, it is desirable for young geologists working in either field to have experience of the counter field as much as possible. In case of being employed in either of both fields surveying for the earth, the systematic action of environmental assessment including global emvironmental problem is important.View full abstractDownload PDF (2468K) -
Isao SHIOZAKI, Tetsuo IGARI, Kazuhiro OONUMA, Hiroyuki YAMAMOTO2000 Volume 40 Issue 6 Pages 367-373
Published: February 10, 2000
Released on J-STAGE: February 23, 2010
JOURNAL FREE ACCESSAt the Akaishizawa tunneling work in the sandstone and clay slate regions, the oxygen content of the air in the tunnel decreased to about 18% accompanying a great quantity of seepage water. To investigate the cause of the decrease in the oxygen content, hydrogeochemical investigations of seepage water were carried out. Dissolved oxygen, Eh, pH, electric conductivity, water temperature, ionic composition, tritium, oxygen isotope ratio and hydrogen isotope ratio were analyzed. From the results, it was made clear that the decrease in the oxygen content was induced by the dissolution of oxygen in the gushed water.View full abstractDownload PDF (1933K)
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