The effect of adsorbed cations on the swelling and slaking properties of clayey soils was examined, using the Na-and Ca-saturated soil blocks shrunk by drying.
The results are as follows:
1) A large difference in swelling between the non-volcanic ash soils and volcanic ash soil was recognized; that is, the swelling of volcanic ash soil was extremely low irrespective of the adsorbed cations (Figs.1, 2, 3, 4).This difference is discussed in relation to the intra-crystalline swelling of soil clay minerals (Fig. 5).
2) In comparison with the swelling of Na-soil of non-volcanic ash soils with that of the Ca-soil, the swelling of Na-soil was larger than that of the Ca-soil (Fig. 4).This difference is discussed in relation to the inter-crystalline swelling controlled by the development of the diffused double layer.
3) As a result of the swelling of three blocks which have different drying-stage, the swelling of volcanic ash soil is extremely low irrespective of the drying-stage, while in Na-soil of non-volcanic ash soils which have high swelling, two tendency is recognized;that is, the swelling of one does not inhibit following the progress of drying, and the swelling of the other does (Fig. 4).The decrease in swelling by drying, involving the low swelling properties of the volcanic ash soil, is discussed in relation to the phenomenon of irreversible aggregation of the soil particles by drying (Fig. 6).
4) The slaking types which each soil block exhibits were divided into four kinds (Photos.1, 2, 3, 4, Table 3).It was clarified that each slaking type is closely related to the swelling properties (Fig. 4, Table 3, Fig.7).

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Recently, it has become evident that the water management system for rational distribution of irrigated water should be clarified, and facilities for water management should be introduced and arranged more pertinently.
The forms of water demand and their properties in farming land are important factors for solving the problems aforementioned, these are understood qualitatively, but their actual conditions are not clear.
Accordingly, in this study the actual conditions of the utilizing forms of intake-water in the mixed areas of a paddy and a dry field are clarified and their characteristic, and countermeasures are discussed.
A more remarkable characteristic is that intake-water can be easily directed into a paddy field.
The basic reason seems to arise from the following fact;excess water in a paddy field does not involve actual damage, and additional water in a paddy field makes easier distribution of irrigated water by other water management;on the contrary, excess water in a dry field brings about wet damage and then regulated without supervision and excess water-intake never occur.
Therefore, in mixed areas of a paddy and a dry field, it is very important to introduce check system for preventing excess distribution of irrigated water into paddy field.

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In this paper, the physical properties, especially the shear strength and pF moisture property of residual andesitic soils, are described.
The results are summarized as follows:
1) The residual andesitic soils are chiefly composed of sand, silt and clay.The clay minerals of these soils are mainly Montmorillonite and Kaolin.These soils have relatively large specific surfaces; therefore, the compaction curves show gentle peaks.
2) The strength parameters, tan φ'and c', of these soils vary considerably according to differences in molding water content.
3) The pF-water content curves of these soils vary considerably according to differences in molding water content.
4) It is assumed from these experiments that the shear strength and the pF moisture property are closely related each other.

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In previous papers, the authors pointed out that some inconsistencies occured when a water hammer of a compound pipeline system was analyzed by the conventional method which transforms a compound pipeline into an equivalent single pipe.The authors proposed a pressure oscillation model to successfully avoid these inconsistencies.In this paper, the pressure oscillation model is further extended to a branched semi-closed pipeline system, so that the water hammer in a branched system is made theoretically clear.
In the pressure oscillation model, the analysis of water hammer is made, presupposing that the velocity energy before the valve chosure is conserved as the oscillation energy, and that the energy is redistributed to each part of the pipeline system under the condition that the inertia and elastic force are balanced.In the present report, first, it is examined how the oscillation energy is allocated to each part of the branched system and how the period of the pressure oscillation is influenced by the allocation. Secondly, the fundamental concept of the allocation of energy is explained by taking an example in the simplest branched system.Then, the validity of this theory is confirmed by means of numerical analysis.
Finally, it is made clear that the above theory can be applied when the time required for the valve to be closure is about one forth of the period of the pressure oscillation.In the conventional water hammer theory, it was known that the governing factors that cause water hammer phenomena change depending whether the valve closure time is less or more than one half of the period.But in a compound pipeline including a branched system, it is made clear from the above theory that the closure time equal to one forth of the period is another crucial point at which conditions for the water hammer phenomena change.

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Some studies have been made over empirical prediction of sediment distribution in reservoirs which is one of the most important factors in designing reservoir. Firstly, historical outline of the subject study has been analyzed and subsequently, some actual application examples of the empirical area-reduction method which has been developed under the leadership of the Bureau of Reclamation of the United States of America to the Japanese reservoir construction project have been investigated.
Namely, notwithstanding almost 90% of the Japanese large-scale dams are classified into types II or III of four standard types on reservoir shape established in U.S.A., their sediment distribution have been probed to show an approximation to that of type I cf the beforementioned reservoir shape classification.
Accordingly, when figuring out the design curve peculiar to the Japanese reservoir dam, sediment distribution area design curves based on reservoir storage curves (See Eqs.4, 5 and Fig.4) and curves to determine depth of sediment in reservoir at dam (See Fig.5) which belong to types II and III are worked out by the method of nonlinear least squares.
Prediction of sediment distribution has been performed over “HN-1” hdam which will have elapsed fourteen years after costruction by applying type II for the evidence of the proposed method the observed results show that type II of Japanese standard has more fairly good agreement between calculated values and observed values in the reservoir storage curve after sedimentation and the reservoir area curve than the type II of U.S.A.standard has.
Furthermore, when utilized for the prediction of cross sediment distribution shape (See Fig.9), it shows that calculated values are fairly good agreement with the observed values under normal water surface level.In addition to that, it shows that prediction of cross sediment distribution shape in the branch reservoir can also be made. On the other hand, when applied to the many other existing reservoir dams in Japan, although the results show that the calculated values are apt to be overestimated in comparison with the actual observed values, the tendency could be observed that type II of Japanese standard had more accuracy in predicing the sediment distribution than the types II or 111 of the U.S.A. standard would have.

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In this paper, it is shown that the changes in effective stress and pore water pressure in the undrained condition in saturated soils can be obtained from a new stress-strain relationship derived from the point of view that soils are regarded as essentially anisotropic deformable bodies. The calculated curves of the stress paths agree well with the empirical results from the tests on Sagami River sand conducted by Tatsuoka et. al as shown in Fig.3.
Furthermore the following conclusions have been obtained:
1) Skempton'spore-pressure coefficient A can be expressed in terms of the deformation coefficients D, G, and K_i introduced in the new stress-strain equations; whether A=1/3 or not is due not to elastic behaviour, but to the isotropic or anisotropic deformation behaviour of soils.
2) In the undrained condition the deformation condition in which the volume of soil does not change dose not govern directly change in pore water pressure but the change in the effective mean normal stress. The pore water pressure change is not independent of external loads (=total stress), the effective mean normal stress is independent of the external loads but depends only on the deformation characteristics of compression and dilatancy.
3) The characteristics of the undrained stress paths can be explained in connexion with the deformation characteristics of compression and dilatancy (Fig. 7).

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A method for slope stability analysis during earthquakes applicable to the proposed optimal design process is described in this paper.
The sensitivity of the safety factor is also used here to predict changes in safety in a linearly extrapolated way, and this has been fundamental throughout these studies.
This method can be applied not only to a part of the proposed optimal design process, but also to the dynamic analysis of slopes independently.
The stability of a slope is discussed to indicate critical conditions expected to appear as a slip line in this study.
The distribution of the response acceleration used in this pseudo-static analysis is determined as it corresponds to acceleration and local instability generated in the dynamic state of the slope.
The procedure as well as the results of the application of this method are stated and the estimation of the risk of the slope is taken into consideration.

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The measurement of temperature distribution in the slab and meteorological observations were carried out and the relationship between temperature variations and meteorological action was found. Using the measurement values and the theory of heat conduction, the analysis of temperature in the slab was carried out.
The summary of the results is shown below.
1) Temperature variations in the slab were large on fine days but small on cloudy and rainy days.(Fig.5)
2) The calculated values of temperature in the slab agreed fairly well with thoes obtained in the measurement.(Fig.6)
3) By consideration of the coefficient of thermal diffusion and the thickness, the temperature variation and distribution in the slab could be determined.(Fig.7, 8)
4) The maximum temperature variation of the slab surface was 30.1°C on a day and 53.7°C during a year.(Fig.9, 10)
5) The maximum temperature differences between the surface and the back of the slab were obtained.(Fig.11.12.13)
6) The correlation between the maximum temperature differences (T_s-T_0.15) _max and the maximum intensities of insolation (J_max) was obtained.(Fig.14)
7) The minimum surface temperatures of the slab (T_{s min}) were nearly equal to the minimum atomospheric temperatures (T_{A min}).Moreover, on cloudy and rainy days, the maximum surface temperatures (T_{s max}) were nearly equal to the maximum atomospheric temperatures (T_{A max}).(Fig.15, 16)
8) The correlation between (T_{s max}-T_{A max}) and J_max on fine days was obtained.(Fig.17)

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