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Volume 27 (1990 - 199･･･
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Volume 27, Issue 4
Displaying 1-5 of 5 articles from this issue
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1923 Nebukawa-station LandslideTosbitaka KAMAI1991 Volume 27 Issue 4 Pages 1-8_1
Published: March 25, 1991
Released on J-STAGE: February 25, 2011
JOURNAL FREE ACCESSThe Nebukawa-station Landslide was triggered by the Kanto earthquake in 1923. Both geological and geotechnical studies point out that the landslide failed rapidly by shearing (compression failure) in the weak pumice layer which was accompanied with the unique deformation named “squeezing-out” that is, the upper layer, mainly massive lava flow, subsided and squeezed out the underlying pumice layer to the front of slide, and the slope collapsed successively.
The elastic-plastic FEM analyses both on the landslide and the simplified three-layers model indicate that the “squeezing-out” is one of the common deformation type on slope which consists of thin weak intertrappean layer (e. g. pumice) and gentle dipping (less than 10 degree) thick rigid layers (e. g. lava).
Several geologic evidences support the idea that the landslide with the “squeezing-out” deformation occurs in dissected slope of stratovolcano, and sometimes leads to the run-off of debris, high speed and long distance; these will then provide basic information useful for disaster prevention planning.View full abstractDownload PDF (4907K) -
Application to Landslide Area Occurred in Hirose District in Nagano CityNorikazu YOSHIZAWA, Masayoshi MARUYAMA, Isao NAGAO, Kouzou MURASE, Shi ...1991 Volume 27 Issue 4 Pages 9-17
Published: March 25, 1991
Released on J-STAGE: February 25, 2011
JOURNAL FREE ACCESSPhotogrammetry technique is applied to landslide behaviour monitoring and underground slide surface analysis in this paper. The landslide behaviour information necessary to measure of disaster reduction and prevention can be obtained speedily, correctly and safely by this technique. Three dimensional displacement of ground objects such as rocks, trees, farms and various artificial structures can be traced by photogrammetries taken at different recording chance. Analyzing these data, moving direction and velocity of sliding block is distinguished. Depth and shape of the underground slide surface can be presumed by least square method. Accordingly, warning region of the landslide is demarcated on a map.This paper demonstrates utility of the photogrammetry applied to observation and analysis of landslide occurred in Hirose district in Nagano city.View full abstractDownload PDF (2624K) -
Tetsuya KUBOTA, Hiroyuki NAKAMURA1991 Volume 27 Issue 4 Pages 18-25_1
Published: March 25, 1991
Released on J-STAGE: February 25, 2011
JOURNAL FREE ACCESSThe detective method for landslide which occures suddenly without any sign seems to be important these days.
To this purpose, a estimation method using the critical slip surface analysis by dynamic programming combined with reliable analysis is established.
It might eliminate a error of unknown under ground condition, and can treat impact factor triggers landslide as well as slope nature, whereas it's not perfect. This method is useful to estimate the landslide susceptibility.View full abstractDownload PDF (1214K) -
Hiromasa HIURA, Kyoji SASSA, Keiji OHTE, Masahiro KAIBORI1991 Volume 27 Issue 4 Pages 26-32_1
Published: March 25, 1991
Released on J-STAGE: February 25, 2011
JOURNAL FREE ACCESSIn this study, the authors have taken a case study of landslide caused by partial liquefaction of sheer zone. The dealt landslide is located at Hakaba in Hamada city in Shimane Prefecture which occurred on the occasion of the Shimane disaster in 1983.
The critical condition of liquefaction of sandy materials without earthquake was studied by the undrained load cotrolled triaxial compression test in use of the Toyoura standard sand and a torrent doposit susceptible of debris flows. As a result, the void ratio and the degree of saturation were found to be the most effective factors concerning the critical condition of liquefaction.
The undrained load controlled triaxial compression test of the soil sampled at the Nakaba landslide has revealed that the grain size distribution characteristic is also an important factor on liquefaction, namely the lack of relatively finer grains leads to the liquefaction on the occasion of rapid loading.
Authors have concluded that, in case of the Nakaba landslide, a small upper landslide gave rapid loading to the lower slope where finer grains above the bed rock had been eroded by ground water, and it resulted in prtial liquefaction of this eroded and saturated zene. It caused the main disastrous landslide destroying seven houses and killing fifteen persons.View full abstractDownload PDF (2918K) -
Hiroshi KIAWABE, Hirofumi SHIBANO, Kunihiko NISHIO, Isao YAMAGUCHI1991 Volume 27 Issue 4 Pages 33-36
Published: March 25, 1991
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSThe relationship between pore water pressure and displacement was examined which had been obtained by the experiment on the artificial occurrence of landslide on the natural slope. The results obtained are as follows.
1) Strain rate increases exponentially as pore water pressure increases.
2) If the relationship between rate of change of pore water pressure and strain rate of the ground can be regarded as the relationship between input and output in the linear system, the spectral ratio of the strain rate to the rate of change of pore water pressure can be approximately expressed by the system function of the Voigt Model or the Bingham Model.
3) It is presumed from 2) that the pore water pressure has had direct effects upon the land deformation in this experiment.
4) In the band of higher frequency the discrepancy between the spectral ratio in 2) and the theoretical values calculated from the system functions is caused by the assumption that the phenomena were regarded as the linear system. It is thought that the actual phenomena show the nonlinearity as in 1) by some factors of the lowering of strength of the ground and so forth.View full abstractDownload PDF (455K)
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