Effectiveness judgement for groundwater drainage works is carrel out on the basis of drop of groundwater level, drainage quantity of groundwater, and/or movement situation of soil mass. And judgement on horizontal effectiveness is carried out by comparing the distributing condition of one-meter depth temperature before and after the groundwater drainage works. Accordingly this method is a qualitative judgement method.
Then the equation for estimating the scale of water vein was reexamined all over for carring out the quantative judgement of horizontal effectiveness. As the result, it is found out that one-meter depth temperature is largely affected by the existence depth of apex of a water vein, and has almost no connection with the scale of water vein. So, it is possible to draw the contour map of existing depth of apex by utilizing the above mentioned characteristic. And it is possible to judge the effectiveness of groundwater damage works horizontally and quantatively by comparing the contour map before and after the works.
A very favorable result was presented when applied the judgement method to a landslide area in Hyougo Prefecture.

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There are problems to be studied on the changes of the soil structures in shear processes on the case of long creep. We studied these problems with a new trial direct shear apparatus and X-ray photographs.
The characteristics of the apparatus are that one pair of an upper and a lower shear boxes about 600mm long is equipped, and the maximum limit of shear displacement of the lower box is 600mm.
Each test was performed as below. X-ray contrast medium was injected in eight lines at a right angle to shear direction into soil sample compacted in the apparatus.
Then shear test was performed by shear displacement prescribed for each sample within from 15mm to 300mm. After the test, the soil structures were observed with X-ray photographs of them.
The soil structures developed through three stages in the shear processes as below. In the initial stage, the contineous deformation in the direction of the sample thickness appears. In the next stage (failure stage), many small and local shear failures appear everywhere in the sample. Then some of them connect to each other, and develop into a clear and thin shear layer as long as full length of the sample. In the last stage (creep stage), some thin soil masses only in the layer relatively slip with long distances, and the result of this phenomenon, the shear layer gradually changes into a creep layer.

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The Morgenstern-Price and Spencer methods are often applied to the slope stability analysis of noncircular slip surfaces. Both of them satisfy the statically determinate parameters and the equilibrium conditions of forces and moments on the each slice. In this paper, the authors show the outline of the Morgenstern-Price and Spencer methods and compare both of the equilibrium formulas of a force and a moment. By this comparison, we point out that Spencer method is equivalent to Morgenstern-Price method using the approximate moment formula for convergence calculation. The authors also clear up the differences of these methods from the analytical results of the model slope. As the statics formulas of these methods have a generality, it is possible to analyze using an interslice force assumption, which is similar to Janbu's.

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The distribution characteristics of landslides in the serpentine belt were investigated. It was clear that the landslide occurred at the edge of the serpentine belt. The geological, mineralogical and soil mechanical causes of this phenomenon were considered. One is due to the geological reason that the talc and clorite are generated at the edge of serpentine belt by the hydrothermal alteration. Another is due to the soil mechanical reason that the shear strength of the talc and clorite is small.

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As a countermeasure against landslide, the effectiveness of vinyl chloride-made multiple type pipes, which consist of an outer pipe with slits and inner pipes was examined experimentally. In-situ tests were carried out by inserting the pipe into gravelly ground. Laboratory tests were carried out by setting the pile into a sand layer compacted in a soil container. It was found from both the tests that the amount of water drained from the multiple type pipe was notably large compared with that drained from the normal single pipe. It was also shown from the laboratory tests that the amount of drainage from the multiple type pipe increases with the number of the soket connecting the inner and outer pipes.

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