In the paddy field, where crop rotation has been practised, the rising of groundwatertable due to the seepage from the neighbouring paddy field has caused the damage of crops. In this paper, the groundwater table in the rotational paddy field separated by the drainage ditch from the neighbouring paddy field was considered for the study of its underdrainage system.
At first, the flow region bounded by an impervious boundaryat a finite depth was considered. The groundwater table was transformed into a straight line by an auxiliary transformation called Zhukovsky's function, such as
G=z-iw/k
where, z is the complex plane, w is the complex potential, k is the hydraulic conductivity and i is the imaginary unit. Then the flow problem could be analysed using the theory of comformal mapping. As a result of this analysis, it was found that the groundwater level was the most affected by the depth of an impervious boundary. When the impervious boundary is fairly deep, the groundwater table will rise up near to the soil surface, but it will fall deeper as theimpervious boundary becomes shallower.
where, z is the complex plane, w is the complex potential, k is the hydraulic conductivity and i is the imaginary unit. Then the flow problem could be analysed using the theory of comformal mapping. As a result of this analysis, it was found that the groundwater level was the most affected by the depth of an impervious boundary. When the impervious boundary is fairly deep, the groundwater table will rise up near to the soil surface, but it will fall deeper as theimpervious boundary becomes shallower.
When the aquifer head is different from the soil surface level, the theoretical analysis for the groundwater table is very difficult. In this case, the author hassolved the problem experimentally using the resistance network analogue of G-plane. The experimental results showed that the groundwater table would always rise up to just the same level as the aquifer head.
From the theoretical and experimental results mentioned above, it was summarized that the groundwater table in the rotational paddy field was raised by theseepage from the neighbouring paddy field and/or from the overlying aquifer, and that the extent of rising was much affected by the boundary conditions of the overlying layer. Accordingly, when the underdrainage in the rotational paddy field which is to be adjacent to a paddy field is planned, it isnecessary to investigate in detail the conditions of the overlying layer, i. e. the existence of an impervious layer or an aquifer and its depth or hydraulic head, respectively.

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In the case of compression oy bulldozer. The soil is not compacted by in impact-force, but by the weight of the machine and vibrations. As the contact pressures caused by a bulldozer are smaller than that by the standard compaction test, the effects of the lower pressure on soils must be examined.
The auther has performed a few experiments uni-axial confined compression test, and the results so far are as follows:
(1) In the case of a contact pressure smaller than 2. 0 kg/cm2, the concave features are seen on Proctor's curve, i. e. the minimum value of γ_d is confirmed.
(2) The moisture ratio at the minimum value of γ_d is nearly equal to the value of Proctor's wopt.
(3) The soil behavior in these compactions may be discussed from the point of view of the bulkingtheory concerned with the capillary forces of soil water

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A method to determine the transmissibility kH by analysing the phenomenon that thetidal fluctuation propagates into the coastal aquifer from the sea with damping effect is studied.
Survey of free groundwater is made. Each sinusoidal wave of the harmonically analysed tidal wave is believed to propagate according to the following cormula
_??_
Transmissibility is determined by the least square method concerning the differences between the observed amplitudes of the groundwater level in the well and the calculated values.
To determine the optimum transmissibility, it is desirable to begin observation with a spring tide, and the shortest practical period of observation is 4-5days.

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In river-water intake in the agricultural water utilization, it is important to estimate the fluctuation in river bed. As a means of solving the problem of bed load, the power spectrum analysis is introduced; and in this connection, the experiments have been made.
For the measurements, a strain gage, which is handy and inexpensive, was employed. With the strain gage attached at the end of a cantilever, the fluctuation in a channel bed free from the water flow was only recorded. The strain gage was placed within the sand bed in an experimental waterway. And an electrical signal correspondent to the fluctuation was produced through the gage; these signals were taken in a tape recorder. In this way, during the course of an experiment, the fluctuation in the channel bed with time could be measured automatically, with water flowing.
The data in the tape recorder were mechanically sampled and digitalized in an A-D converter in corporated in the spectrum computer; and the auto-covariance function and the power-spectrum density function were computed.
As the result, it was revealed that the phenomenon being observed was a typically random one and in the unstable state of sand in a channel bed such as the front of a sand wave the auto-covariance function was with a considerable attenuation slope.
Furthermore, the power-spectrum density function itself was varied periodically. Then though no definite conclusion was possible because of the insufficient data obtained, the fluctuation tended to be large when the dimensionless quantity of the tractive force in flowing water was about 0.2-0.25.
In the future, basical experiments will be made systematically by the procedure described, thereby accumulating the necessary data. And thus the actual situation of bed load and river-bed fluctuation will be made clear from the dynamic characteristics; this information obtained should contribute to the design in river-water utilization.

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This paper shows that a stability analysis of anchored sheet piles may be done applying the principle of least work, when a suitable distribution pattern of earth pressure is assumed. An example is shown in Fig. 1.
aking use of this result, one can easily obtain the tension of an anchor rod, the depth of the buried portion of a sheet pile, and the maximum bending moment and the point it which it occurs when the angle of internal friction is decided, and also the appropriate location of the anchor rod.
Furthemore, the stability analysis of sheet piles without anchor rods for the same earth pressure distribution is shown.

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The Author measured the stress generated by a pneumatic tyred roller (25t) and compared the theoretical values which are calculated under an assumption of the validity of the principle of superposition (Fig. 4-5). Pneumatic pressure of the tyred roller (3. 8 kg/cm²) used for contact pressure. Theoretical stress distributions of Z, Y and X directions are shown Fig. 1-5. Fig. 9-1-9-4 show the experimental stress distributions X direction for Cr. Rm and Tr.
From those studies we find as follows,
(1) Theoretical values almost coincide with the measured values in the case of low speed of the roller or compaction on cohesive soil (Cr., Rm.).
(2) Stress grows larger with the compactive speed of the roller and with the roughness of the ground.
(3) Theoretically and experimentally, the vertical stressσ_z is much larger than horizontal stress σ_x, σ_y which is generated by the vertical load and horizontal load due to the friction between the roller and the soil surface. So that it can be said that σ_z mainly contributed to the compaction.

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We measured stress in the soil body generated by a vibratory roller and compared the statical analysis due to elastic theory (Fig. 5).
The frequency used for compaction was 0-2000 rpm While roller running from the bottom to the top speed. Those experimental data show several results as follows.
(1) The Contact pressure of the vibratory roller had better be considered a rectangular load rather than a line load, taking into account the bearing capacity of compactive surface ground and the stress distribution in the soil.
(2) The higher frequency (f_I) measured by an indicator of the roller generated the greater stress in compacted ground.
(3) Although the theoretical stress σT almost coincides with the measured stress σR at f_I f_I=0, σ_R is usually much bigger than σ_T.
(4) So long as we consider that the dynamic force is generated by the unbalanced mass of the roller, the stress in the field is not to be so large as measured. So the difference between these two values may result from the resonance of the soil body.
(5) σ_R decrease with the roller speed being larger under the same frequency. So that the better compaction will be got with the slower speed for this type of vibratory roller.

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The dynamic properties of the ground while being compacted by the vibration oi vibratory roller were evaluated with the help of laboratory experiments. The results are as follows.
(1) Assuming the ground and roller system as a Voigt model, we need require K, M in eqs.(1) to get resonance frequencies f_n. We can get k_s by eqs.(7)-(12) substituting 1/ 10. of Young's modulus from a triaxial test for E, because of the relationship between elastic and plastic deformation from laboratory experiments.
(2) Measured resonance frequencies are 25-29 Hz for Cr., 27-32 Hz. for Rm. and 30-33 Hz. for Tr.(Fig. 3).
(3) Calculating results by the above procedures are rather smaller than experimental values except Tr. which almost coincide, but are much better than other equations.
(4) f_n of the ground is very much dependent on the density of field.
(5) The coefficient of damping is smaller than 0.1.
(6) From the above results we are able to get the dynamic properties of the ground by a vibratory roller and those results can be said to coincide with the values measured already by other procedures.
(7) Suppose that the compaction of soil depends only upon the magnitude of the force on the soil body, we had better compact according to the resonance frequency of the soil.

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Soil Salinity is a great hindrance for the development of agriculture. A theory of desalinization of saline soil with the cleaning irrigation was developed.
It was based on the macroscopic aspects of the process of desalinization. It was assumed that there were three phases, based on different forc es, in the process of desalinization. They were:(a) the adsor. ption-desorption isotherm of ions on and in the vicinity of soil particle surface.(b) The diffusion mechanism of the soluble salts in the pore spaces of soil body.(c) The transportation of the salts by the major force of water flow coupled with the diffusion through the soil cracks and surface. A fundamental equation has been developed from the above conception of the theory. The analytical solutions in special cases and the numerical solutions of the fundamental equations were also derived. The subsequent paper will be concerned with the experimental verification of this theory.

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In Part 1. of this series, the theory was developed to describe the desalinization process from the adsorption-desorption isotherm, diffusional and hydrodynamic point of view. In the present paper, experimental verification is carried out and the results are discussed in relation to the theory.
The saline soil, subjected to this experiment, was taken from the polder reclaimed land from the sea. The experiment was conducted in a specially designed Soil Electrode Box made of wood, in such a way that the desalinization process was not allowed to be disrupted.
The theory was verified by the following steps.
(1) The Theoretical Diffusion Curve obtained from the theory was compared and contrasted with the Observed Diffusion Curve.
(2) The theoretical amount of the leached salt derived from the theory was checked with the empirical results.
(3) The calculated data of leached salt, obtained from the theory with respect to mean flow velocity were tested with the experimental results.
(4) By the Match-Point Coordinate Method, the soil constants such as α & β were determined from the Diffusion Curves.

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In part 1 and 2 of this series, the theory of desalinization of saline soil and its verification were developed and described. In the present paper, the application of the theory was considered from a number of points.
(1) Effect of α-diffusion constant on the desalinization process.
(2) Effect of β-desorption constant on the desalinization process.
(3) Effect of V-flow velocity on the desalinization process.
(4) Combined effect of the factors on the desalinization process.
(5) Determination of soil constants α and β.
The symbols used below have identical meanings to those used in Part 1 and Part 2.

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