Most of hydrogeologists are facing many problems closely related to groundwater flow in slope, such as runoff in mountaneous area, slope failure, land slide and so on. It has been pointed by many authors that soil pipes developing in slope play an important role on the flow. From the reason, it can be said that the study on effect of soil pipe on the groundwater flow is indispensable to solving the problems.
From the view point, transient behavior of saturated-unsaturated groundwater flow in idealized slope having a soil pipe in it was studied by the use of finite element method of three dimensional form. In addition to the numerical analysis, two types of experiment were performed to prove the analytical results.
Obtained results are as follows;
(1) Finite element method of three dimensional form is very useful to study the effect of soil pipe on the transient behavior of groundwater flow in slope.
(2) Flow velocity becomes high only in soil pipe. Although the total amount of effluent quantity from seepage face become larger, velocity distribution on the face is almost uniform under the condition that the pipe does not reach the face.
(3) Pore pressure become considerably high at terminal point of the pipe in slope.

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Some simple and rapid tests were tried out, which were the tests to get water absorption of rock fragments (WSL) and of the commuted and desiccated powder of the same rock (WA). The extent of slaking (rapid disintegration of soft rock in process of water absorption) is observed during the WSL-test.
The extent of slaking is ranked in 5 grades (A-E) in observation and closely related to the following index of slaking (ISL).
ISL= (WSL-WSAT) / (WA-WSAT) WSAT means saturated moisture content of intact rock before slaking or swelling.
The maximum swelling strain (or expantion: ΔV/V₀) or pressure (PSW) is sufficiently estimated from the values of WA and γ_d (dry density) or WSAT which are able to measure simply. WA represents the latent possibility of expantion of the constituent particles upon removal of the cementation of rock fragments regardless of the clay mineral composition.
The maximum value of ΔV/V₀ in an intact rock is corresponded to the ΔV/V₀ of the artificially compacted rock after commuting, and the ΔV/V₀ of the intact rock in any drying and wetting process can be estimated from this maximum ΔV/V₀ multiplied by the ISL. ΔV/V₀-WA-γ_d diagram and the photographs illustrating the typical features of slaking in each grade are prepared in this paper to estimate ΔV/V₀ and ISL easily.

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The Rock block slide occurred at Hitotsu-tsubota, Showa-mura, Fukushima Prefecture, Japan is found in an almost flat area topographically. Therefore, it seems to be the good field to investigate the geological factors led the rock to block slide except the landform factors.
The present paper shows the mechanism of the rock block slide occurred in this area using geological, geomorphological and hydrogeological data obtained in this work. In this process it seems to be very important to analyses strata with interformational folding from geotechnical and mineralogical method. Especially on the characteristics of clayminerals and quality of groundwater, associated with the sliding and/or bed rocks should be studied in detail.

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