Landslides

Measurement of the Apparent Friction Angle During Motion by the High-Speed Ring Shear Apparatus

Kyoji SASSA, Jong-Hak LEE

1993 Volume 30 Issue 1 Pages 1-10_1
Published: June 15, 1993
Released on J-STAGE: June 28, 2010

DOIhttps://doi.org/10.3313/jls1964.30.1

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The motion of landslide will be regulated by the internal friction angle and pore pressure during the motion of landslide. Types of pore pressure generation along the slip plane during the motion of landslide have been classified in three types. Sassa has proposed that pore pressure generation in the typical long run-out landslides such as the1984 Ontake landslide in Japan and the 1983 Sale landslide in China should be resulted from the rapid loading of landside mass onto the saturated alluvial deposits. Samples were collected from the alluvial deposits on which the mentioned-above landslides traveled, and the apparent friction angle during the rapid loading condition was measured by the high-speed ring shear apparatus. A new sled model (originally proposed by Heim) using this measured apparent friction angle could well explain the reason of low apparent friction and long travel distance of both disastrous and very mobile landslides.

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Quaternary Volcanic Activity and Ancient Landslides in the “Green-tuff” region of the Tohoku district

Shinro ABE, Hiroshi MORIYA, Tomio MORIAI

1993 Volume 30 Issue 1 Pages 11-18_1
Published: June 15, 1993
Released on J-STAGE: February 25, 2011

DOIhttps://doi.org/10.3313/jls1964.30.11

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The date of the ancient landslides in the “Greentuff” region of the Tohoku district has been approximately determined by rediocarbon dating and so on.
However, the mechanism of the occurrence of the ancient landslides has not been defined except for the vague idea that it is probably influenced by the climate, eustratic change in sea level, and landforms.
The present detailed studies of some large ancient landslides in the “Green-tuff” region with special emphasis on the distributive forms of sliding rock mass and phroclastic flow deposit show that the occurrence of the original rock slides is greatly affected by the Quaternary volcanic activity at the end of the Diluvium and in the earliest Alluvium times.

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Landslide Deformation and Movement based on Tow Dimensional Surface Displacement

Kaichi HAYAKAWA, Nobuyuki TAKAHAMA

1993 Volume 30 Issue 1 Pages 19-26_1
Published: June 15, 1993
Released on J-STAGE: June 28, 2010

DOIhttps://doi.org/10.3313/jls1964.30.19

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The authors proposed an analytical approach of the two dimensional distributions of surface displacements. The measurments by the electro-optical distance meter have been carried out in each snow cover and summer periods since 1990 at Higashi-nomyo landslide site in Niigata Prefecture. The results are as follows:
1) The characteristics of deformation and movement of the slide blocks became clear after calculating the two dimensional distribution of movement and strains from displacement measurments.
2) The slope movements in snow cover and summer period reveal the different patterns.
3) The contour line map of surface displacements is useful to understand the whole aspect of the slope deformations and movements.

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Change Type of Pore Water Pressure in Landslide Area

Kiyoteru MARUYAMA

1993 Volume 30 Issue 1 Pages 27-35_1
Published: June 15, 1993
Released on J-STAGE: February 25, 2011

DOIhttps://doi.org/10.3313/jls1964.30.27

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The behaviour of pore water pressure was investigated in some landslide areas. In this report, the type of pore water pressure was classified, and some remarks were made on the method of slope stability analysis in case that the excess pore water pressure is generated.
Further, the method to select the suitable countermeasures for landslide stabilization planning was examined. As a result of this analysis, the behaviour of pore water pressure change is classified in four types. It is necessary to install countermeasures under the consideration of each type of pore water pressure change.

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Determent Effect of Anchor Works Constructed in Landslide by Using Discrete Analysis

Hiroyuki YOSHIMATSU, Morito NAKAYAMA

1993 Volume 30 Issue 1 Pages 36-44_1
Published: June 15, 1993
Released on J-STAGE: February 25, 2011

DOIhttps://doi.org/10.3313/jls1964.30.36

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This paper discussed some problems in regard to the design of anchor work constructed in landslide. Discrete analysis of RBSM (Rigid Bodies spring Model) was used for the evaluation on mechanical effect of anchor arranged in simple slope models. The obtained basic information was as follows.
The whole mass movement along the slip surface is prevented by anchor, however partial failure in interior zone of mass occurs by the increase of external force. Forms of partial failure are different depending on the difference of anchor location. The most suitable anchor location exists in the viewpoint of partial failure.
The anchor stress analyzed by RBSM is lower than the calculated one by using present design equation based on Fellenius method for anchor work. The difference of both originates from the following reason. The former method evaluates the equilibrium conditions of internal force between each slice, though the latter doesn't. The most suitable anchor location decided from the view point of stress is not always same one from Partial failure.

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[title in Japanese]

[in Japanese]

1993 Volume 30 Issue 1 Pages 45-56
Published: June 15, 1993
Released on J-STAGE: June 28, 2010

DOIhttps://doi.org/10.3313/jls1964.30.45

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