In Chausuyama landslide area, drainage works have been performed repeatedly since 1966, and the lowering of the groundwater level in the upper part of the sliding area has been attained by about 20 meters. The movement of soil mass is on the decrease from 1971 to 1975 and the sliding activity is fairly stabilized. The Y-Y measuring lines area in the middle of the secondary sliding area and the south part of Sankaku-yama at the top of the sliding area grow stable. The stabilization of soil mass between the middle and the southwest side of the upper of the sliding area is remarkable. The main problem to be settled in future is to control the movement of soil mass along the C-C measuring lines.

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This paper describes the studies on the states of stress and deformation in the pile of Duble type against the landslide and the movement of the soil around the pile by the model testing.
The experimental results are as follows;
(1) The pile of Duble type in the upper sliding surface can be considered to be a cantilever beam on which a uniformly distributed load (passive earth pressure) acts. But when the pile in the upper sliding surface surpasses a certain length, the amount of reaction increases with rapidity.
(2) The bending moment distribution on the part of the lower sliding surface can be calculated in the same manner as that of the Caisson wall, and maximum bending moment acts on this part.
Based on the exprimental formulas deduced from the above model testing, we have calculated the stress distri bution of the pile of Duble type at Oshida landslide area in Akita prefecture. The resultant value approximattely correspond to the experimental value.

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In spite of use of a strain gauge pipe, we can't always find a slip surface of landslides successfully. One of these causes is due to the interval of gauges. By using the equation of Chang, the interval of gauges can be decided. The authers discuss the interval of gauges for each type of landslides; clays slide, debris slide, weathering rock slide, rock slide. For example the gauges should be put on the surface of a vinyl chloride pipe at the interval of less than 90 cm for the type of clays slide, and for weathering rock slide at a space of at least 45cm.

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Niigata prefecture, it is well known as the occurence areas of landslides in Japan. Most of these landslides concentrate on south-western parts of the prefecture. Every year, extensive damages have been inflicted in these parts by disaster of landslide. Therefore, countermeasure for preventing such disaster must be done urgently.
For discussing stability of slopes in landslides areas, it must have full knowledge of soil properties in soil engineering aspect in these places. However, the investigation and research from soil engineering point of view are not sufficient.
The accumulated data obtained at various locations in Niigata prefecture are analyzed, and some soil properties of landslide areas are made clear. Moreover, the tests based on soil engineering aspect were performed and a few important facts can be detected.

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After the heavy rain the landslide occurred at the beside of local road near Kuroda village, Manba-cho, Tano-Gun, Gunma Prefecture in J apan on the middle of June, 1974.
By the boring for geological survey and prospect working of this place, we recognized the nature of the test pieces of rocks and clay minerals.
This area mainly consists of schalstein of paleozoic system as we called Chichibu formation including thin layers of slate and chert.
Not only the test boring but also the observations on local tohography, it was considered that many landslides has been occurred from early times.
We can fined the two kinds of clay minerals in the cracks and joints of altered strata. One of them (sample No.1002 and 1003) has the elements of fine minerals derived from country rocks and also ammounts of clay minerals (micaceous clay minerals and chlorite) and occured from the horizontal thin cracks and joints in the country rocks, not so long continued.
The other (sample No.1001) comes from the more thick clayey beds of altered zone of schalestein strata, consists of chlorite, micaceous clay and little ammount of montmollironite.
Especially we can recognized the random mixed-layers of mica-montmollironite minerals.
The landslide of this place is considered by such clay minerals as random mixed-layer mica-montmollironite, montmollironite, mica clay minerals and chlorite filling up the pore of rock bed.

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