The baseflow recession characteristics of a small mountain river are investigated using a two-dimensional sand model. The results indicate that the baseflow recession curve is affected by the characteristics of groundwater recharge from the unsaturated zone and the diffusive flow in the aquifer. An unconfined ground water model with a recharge from the unsaturated zone is developed for the baseflow model of a small mountain river. The recession curve of this model is Q=Q₁ exp (-δ₁t)+Q₂ (Δh) exp (-Δ₂t), where the first and second terms on the right side are the flow components from the unsaturated zone and the aquifer, respectively, and Δh is the initial difference between the groundwater level at the river and groundwater divide. The baseflow recession characteristics depend on δ₁, δ₂ and the Q₁/Q₂ (Δh) ratio. The equation agrees well with the baseflow recession curves of the study rivers.

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When selective withdrawal from a slit in a two-layered stratified fluid system is supercritical, withdrawal layers are formed in each fluid.
In this paper, an attempt has been made to obtain information on this fluid system. Our system was two-dimensional, steady and laminar.
In this study, it was found that the characteristics of withdrawal layer in our system is much the same as the flow of linear and multi-stratified fluid. That is, the velocity profiles show similar figures, and the maximum velocity is in proportional to x^-1/3 and the thickness of withdrawal layer is to x^1/3 (x is the distance from slit).

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Studies were made on the characteristics of compaction in peaty soils so as to obtain fundamental data on the use of low area. The results obtained are summurized as follows:
(1) In an unrepeated drying process, the dry density (γ_d) of the peat soil increased with a decrease in the moisture ratio (w) attaining a maximum (γ_dmax) under a air-dry condition (Fig. 1).
(2) In the wetting process of peat soil, a peak was found on the compaction curve obtained by the repeat method, but no peak on the compaction curve could be found by the unrepeat method (Figs. 2, 3).
(3) The compaction curve for the non-fiber part of peat soil passed through the No.150 sieve (105μ) under water and showed a peak value of dry density, but no peak was recognized on the compaction curve for the fiber part (the residue on the sieve) (Fig. 4).
(4) In regard to the drying process of peat soil in compaction test by the unrepeat method, the smaller the initial moisture content of the peat soil, the higher was its dry density (Fig. 6).
(5) In peat and muck soils, the larger the content of sand, the higher was the maximum dry density and the smaller the optimum moisture content (w_opt) (Figs. 7, 8).

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In regard to the rational use of fields, it is important to understand seasonal changes in soil aggregates under cultivation conditions.
In this paper, both qualitative and quantitative changes in soil aggregates following the cultivation of soybean or rice, are studied seasonally and distributionally.
The results obtained are as follows:
(1) In autumn, aggregates are formed with the cultivation of soybean. Though whole aggregates are not always stable quantitatively, enlarged stable aggregates remain until the following spring.
(2) The degree of aggregate formation following cultivation of rice depends mainly on the management of soil water. Large stable aggregates are formed under relatively humid conditions involving little change in moisture.
(3) Change in aggregates is better expressed by taking into consideration the rate of solid phase and organic matter in the soil.
(4) Many physical properties of soil except aggregates do not change remarkably with crop cultivation.
Based on the above, crop cultivation does not harm the physical properties of soil, but actually, makes the soil somewhat better.

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The rotational motion of water molecules absorbed on the clay was investigated. According to experimental second moments calculated by the N. M. R. spectra of the proton, the motion depended on ω°. On investigating the values and changes in the pattern of the motion for angle ω, it was concluded that the proton-proton vector in the water molecu, les rotated about an axis of 45° with the clay platelets (Fig. 1).
Based on our results, it is our assumption that the proton-proton vector rotated about an axis of 45° with the clay platelets in the solid state. The theoretical second moments in the rotational motion were calculated. The theoretical values agree well with the experimental results (Figs. 6, 7, 8).
As shown in Fig. 15, it is clear that the angle β_{n, jk} of the rotational motion decreases with the temperature.

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The author showed the observational results of the farm road which was constructed by the preloading method, and which was investigated over a period of three years including both a test of the embankment and the regular construction, and an arrangement of the characteristics and the problems of the settlement of the farm road. Moreover, the author applied the two-dimensional elasto-plastic consolidation analysis by the finite element method to the measured examples and examined the adaptability of the theoretical analysis. And then, the author ascertained that the theoretically calculated values of the consolidation time-settlement agreed very well with the measured ones. Moreover, it became clear that the variations in the pore water pressure and stress could be correctly assumed.

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This paper deals with the physical and chemical properties of clayey soils reclaimed from Tokyo Bay sediments by sand pump dredging, and a comparison is made with andosol and red and yellow soils.
The reclaimed land soils were found to consist of montmorillonite and to have large surface area, cation exchange capacity, soil pH and electric conductivity, and contained large amount of salts.
The liquid and plastic limits of these reclaimed land soils decreased with drying, desaltation and by treatment with calcium, magnesium, potassium and sodium chloride solution.
The addition of potassium chloride decreased the liquid limit of these soils, since pottasium ions inhibited the infiltration of water within the interlayers of the montmorillonite.
In a soil solution of reclaimed land soil improved with calcium, magnesium, potassium and sodium chloride, potassium ion was distributed in a greater concentration than other ions in the field of higher pF.

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This paper presents an analysis of drying shrinkage within a concrete structure. If drying shrinkage is in proportion to water content, the governing equation for drying shrinkage can be directly solved by F. E. M.
First, the analytical results of a 10×10×40cm specimen were found to be in agreement with the experimental results obtained by Kiyama et al.
Secondly, the analysis of a real structure showed small drying shrinkage at the surface following placement. This implies that the proper choice of K and f is important.
Also, drying shrinkage stress was calculated using the thermal stress equation.
Finally, a new equation has been proposed for this calculation.

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In a series of studies, a seepage failure problem of a piece-wise homogeneous sand column caused by a vertically ascending seepage flow is considered. In this paper, based on the previous papers, the effects of the stratified filter with head loss is clarified.
The stratified filter with head loes is referred to as a piece-wise homogeneous sand column which consists of the following sand strata: the upper stratum has a greater coefficient of permeability than the lower stratum. The one-, two-and three-layered sand columns shown in Fig. 2 are compared with one another to clarify the effects of the stratified filter. The stratified filter with head loss has the following effects, from the point of view of internal effective stress:
(1) Critical difference he in the total hydraulic head between the topmost position and the bottom position of the stratified filter is identical in the one-, two-and three-layer cases.
Considering, however, the frictional resistance (at a critical time) between the vertical acryl cylinder wall and sand particles in an experiment with the acryl cylinder model; as for h_c
(one-layer case) <(two-layer case) <(three-layer case), according to the residual effective stress (at a critical time).
(2) Taking an area of the internal effective stress diagram as the parameter of the stability of the stratified filter; as for the stability (see Table 1),
(one-layer case) <(two-layer case) <(three-layer case).
(3) As for the maximum hydraulic gradient which takes place in the bottom layer of the stratified filter (see Table2),
(one-layer case) <(two-layer case) <(three-layer case).
But, on the other hand, as for the minimum hydraulic gradient which takes place in the top layer of the stratified filter (see Table 2),
(one-layer case) >(two-layer case) >(three-layer case).
Considering (2) and (3), the following is obtained:
(4) The lower layer of the stratified filter spends, in upward seepage flow through it, the greater part of difference h in the total hydraulic head between the topmost position and the bottom position of the stratified filter, and the upper layer of the stratified filter contributes to the increase in internal effective stress (i. e., the increase in stability).
Judging from the way each layer of the stratified filter spends, in upward seepage flow through it, difference h in the total hydraulic head (see (4)); the stratified filter has the following characteristic:
(5) By appropriately increasing the number of layers of the stratified filter, the location of the layers where the grain-size distribution must be considered to prevent sand particles from being scoured are able to be limited to the lower portion of the stratified filter.
The design of the stratified filter is related to the three following factors:
(i) the stability of the stratified filter,
(ii) the condition that sand particles must not be scoured, and
(iii) the restriction of the amount of flowing water (i. e., the restriction of water leakage).
(In practice, however, a filter is mostly positioned to meet condition (ii) only.) Conditions (i), (ii) and (iii) are related to the hydraulic gradient within each layer of the stratified filter, and are related to the coefficient of permeability of each layer. It is, therefore, considered that the stratified filter with head loss should be designed from the viewpoint of internal effective stress, taking the coefficient of permeability of each layer of the stratified filter into consideration.

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A lot of data has been obtained due to the recent development of a laboratory apparatus and the numerical analysis methods. However, it seems difficult to simulate the behavior of a fill-type dam subject to earthquake loading, taking into account the pore water pressure developed and the reservoir effects regarding the numerical procedure. Therefore, model tests have been remarkable in evaluating the earthquake-resistant characteristics of embankments.
in the previous papers, the results of the model test supposing the embankment immediately after the construction were investigated by numerical analysis and the system identification procedure. In the present paper, another model test is conducted using a model embankment, of which material is almost completely saturated by the so-called CO₂ replacement. There after, the effects of the reservoir level and of the pore water pressure on the dynamic behavior of the embankment are examined by comparing with the previous results. Those effects are, moreover, investigated with respect to the dynamic deformation parameters identified from the response acceleration records in the same way as shown in the previous work.
The following conclusions are drawn:
1. The embankment with a reservoir should be recognized as the embankment-reservoir vibration system.
2. The pore water pressure developed is affected by the spectral characteristics of the input motion.
3. The dynamic shear rigidity of the embankment decreases in the embankment-reservoir system, while the damping ratio is developed to a lesser extent at the larger strain level.
4. Densely compacted, the saturated model embankment with a reservoir is possibly liquified at the lower layer contrary to the slope failure of the unsaturated model with the reservoir empty.

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