All issues
Volume 55 (2014 - 201･･･
- Issue 6 Pages 279-
- Issue 5 Pages 216-
- Issue 4 Pages 156-
- Issue 3 Pages 110-
- Issue 2 Pages 64-
- Issue 1 Pages 2-
Volume 55, Issue 2
Displaying 1-3 of 3 articles from this issue
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Original Article
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Shallow Landslides Induced by Rainstorms in the Area Underlain by the Cretaceous Izumi Group, Ehime PrefectureMakoto MATSUZAWA, Masahiro CHIGIRA, Shoji DOSIDA, Takeshi NAKAMURAArticle type: Original Article
2014 Volume 55 Issue 2 Pages 64-76
Published: June 10, 2014
Released on J-STAGE: July 31, 2014
JOURNAL FREE ACCESSMany landslides were induced by the heavy rainfall of Typhoons 0415 and 0421 in Niihama city, east Ehime prefecture. Detailed geomorphic analysis by using airborne laser scanner and geologic investigation revealed the geomorphic and geologic features of landslide sites. The affected area is underlain by the Cretaceous Izumi Group consisting of alternating beds of sandstone, mudstone, and granule conglomerate; the Izumi Group had been supposed to be not susceptible to shallow landslides by rainstorms. Landslide sites were not controlled by lithology but were controlled by the intensity of weathering: the most common landslides were shallow slides of a soil layer derived from heavily weathered rocks. Airborne laser scanner detected landslides of 2004 and of previous years and convex slope breaks. Landslide crowns are aligned laterally to form convex slope breaks, which are "denudation front": Slopes just above these denudation fronts and on heavily weathered rocks are the most susceptible slopes to rainstorms.View full abstractDownload PDF (21049K)
Report
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Osami ENDO, Yoshitaka MATSUURA, Masayasu FUKAMIZU, Takehide NAGASE, Ko ...Article type: Report
2014 Volume 55 Issue 2 Pages 77-85
Published: June 10, 2014
Released on J-STAGE: July 31, 2014
JOURNAL FREE ACCESSWe were compared classification of the rock mass including open cracks (opening width is 0.5 - 2 mm) by observing open cracks in the borehole and in the inspection adit, and by using seismic tomography. As a result, it was confirmed that can be divided by the seismic velocity(Vp) quantitatively into the zone of including open cracks and including almost no open cracks. The seismic velocity of the zone including open cracks was 0.5-2.4 km/s, the seismic velocity of the zone including almost no open cracks was 2.4-4.0 km/s.View full abstractDownload PDF (16010K)
Short Report
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Youco ISONO, Takayuki KIMURA, Satoru NAKASHIMAArticle type: Short Report
2014 Volume 55 Issue 2 Pages 86-92
Published: June 10, 2014
Released on J-STAGE: July 31, 2014
JOURNAL FREE ACCESSIn order to examine the possible application of near-infrared spectroscopy for engineering geological materials, we measured near-infrared reflectance spectra on 10 grains of feldspars for eight test pieces of Sanin granites and eighteen test pieces of Ryoke granites, which are measured for their uniaxial compression strength and P and S wave velocities. By converting reflection spectra to absorption spectra using Kubelka-Munk formula and by calculating areas of absorption bands at 1,450, 1,950, 2,250 and 2,350 nm, the average band areas of feldspars are correlated with the rock strength. As a result, the 2,250 and 2,350 nm bands (hydroxyl groups) for feldspars of Sanin granites and the 1,450 and 1,950 nm bands (interlayer or adsorbed water) for feldspars of Ryoke granites were found to have relatively good negative relations with the rock strength or P and S wave velocities. Since X-ray powder diffraction analyses and polarizing microscope observation detected sericite, chlorite and smectite-clay minerals, these near-infrared absorption band areas can be taken as indicators of hydration degrees of feldspars. These band areas can also be used as indicators of rock strength. Although further quantitative analyses are needed, near infrared spectroscopy can be a potential non-destructive technique for evaluating the rock strength.View full abstractDownload PDF (3980K)
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