In this paper, the changes in the undrained shear strength in the consolidation, swelling, and recompression processes for remolded Ariake marine clays are investigated from the point of normalization of the strength characteristics of the clays. It was found that the strength characteristics in the consolidation, swelling, and recompression processes for remolded Ariake marine clays can be normalized using the generalized Hvorslev failure criterion and overconsolidation ratio, OCR, defined by Hvorslev. This normalization procedure embraces the usual one in which the overconsolidation ratio, OCR, is used, and can be applied to clays exhibiting a nonlinear relation between the shear strength and effective normal stress at failure in the normal consolidation process.

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The roof structure of large-size and low-cost cattle barns (hereafter called the example barn), which has an attic space used for fodder store, is investigated from the standpoint of environmental design, for the main purpose of establishing some conditions for avoiding falling dew.
First, a laboratory experiment is carried out using similar materials used for the roofing of the example barn. As a result, the heat transfer coefficient of the natural convection of the material can be obtained suitably as 2.3 W/(m²·K). By use of this value, the improvement of the roof structure used low-cost materials can be proposed as the example barn.
Second, using the data obtained by the investigation of the example barn with falling dew, the ventilation estimate is done by means of three stationaly methods consisting of heat and moisture balance and the architechtural method for the example barn.
As a result, these three values estimated roughly agree with each other.
Third, the physical values of the low-cost cattle barn are simulated as an object of the estimations, obtained by means of using the heat balance equation with the environmental data investigated and the ventilation done. As a result, a rate of increase of more than 50% of the ventilation and a rise in the air temperature can be estimated.
Last, it should be able to say conclusively that, the example barn can not avoid falling dew on the inside part of its roof. Then, as a counterplan to avoid falling dew on the inside part of its roof, a new low-cost structural design of the roof, another look at the size and position of the ventilation should be looked into. Moreover, a fan should be installed for free circulation of the air inside of the barn.

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A highly versatile and efficient numerical model for computing the steady-state backwater profiles in interconnected open channel networks is developed by a combined use of the finite element methed and the Newton-Raphson method. The gradually varied flow equations in differential forms are directly cast into the algebraic finite element equations by the standard Galerkin procedure. The nonlinear element equations as well as the exterior and interior boundary conditions are adapted into a linearized recurrence form in order to render them amenable to the Newton-Raphson scheme. The emphasis is made that, ensuring solution convergency in iterative procedures, the model can successfully be started from the relaxed hydrodynamically cold situation. For verification checks, a few applications of the model are made for the problems for which the differently founded solutionsare available. The solutions obtained, for a complex network, are in close agreement with those of the finite difference model. Also, it is found that the finite element solutions can be more rapidly converged to the correct ones, after only five or six iterations, when compared with the finite difference solutions.

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Effect of soil management on the spatial variability of the soil's physical properties of a double-crop paddy field was examined using statistical methods such as geostatistics. Samples were collected along three transects at 0.5 or 1.5mintervals after the wheat and rice harvest in one paddy fi eld and additional samples were collected along two transects at 3 m intervals before and after soil pudding in another paddy field. All samples were collected from the soil surface and were 100ml in volume. Variables include soil moisture content by weight, soil moisture content by volume and bulk density. The results are summarized as follows:
1. The spatial pattern of soil moisture and bulk density was greatly changed before and after soil puddling.
2. Almost all of the semi-variograms of soil moisture and bulk density of soils, collected after wheat and rice harvest, showed the “pure nugget effect” and no spatial structure was observed.
3. From these results, it was considered that both rotary tilling and soil puddling made the topsoil of a paddy field uniform and the spatial structure made by this management has been maintained temporally.

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To determine the adequate sprinkler system for spraying agrichemicals in citrus groves, the characteristics of the spraying droplet were investigated experimentally. The outline of this study is as follows.
The highest loci of the spraying droplet by the MI type sprinkler with a 27?? nozzle angle was 5-6 in above the ground's surface in case of riser height of 2 m. Therefore, the droplets, especially small ones were easily influenced by wind velocity. The adhesion of the chemical solution was less on the backside of the leaves because of the secondary splash on the leaves or branches was weaker by reason of the small, vertical and slow velocity of the droplets.
As a result of experimenting on the adhesion at different sections on the crown, a sufficient amount of adhesion was obtained at the leaves at the top or middle section of the crown, but it was inferior on the reverse side of the leaves, especially at the skirt or inside of the crown. It was clarified that the adhesion rate for the droplet sprayed with a sprinkler at an angle of 20°-30°was superior to that of 60°-90°.
A sprinkler which can be spray droplets having a diameter from 1.5 to 4.0 mm with a lower angle must be required for increasing the adhesion rate at the skirt and inside of the crown.
As only 15% of the sprayed agrichemical solution adheres to the crown, integrated and comprehensive investigations are required to improve the adhesion efficiency by considering the following factors such as the type and arrangement of the sprinkler, sprinkling method, and reformation of the tree shape.

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On the basis of the former report, the adhesion rate for various types of sprinklers were investigated, nozzle angle improvement was carried out and its effect were verified.
The effect of attaching a wire gauze to the sprinkler head to concentrate the spray with a certainarea was investigated. The results are summarized as follows.
Intermediate pressure sprinkler (M) was most adequate for spraying of agrichemicals, and therewas no difference in the efficiency of the chemical adhesion between the MI and M III type.
The nozzle angle determining the spraying velocity and the spraying angle of the droplets wereinvestigated with improvements being made. As a result of experiments on the adhesion efficiency, the most suitable angle was between 15-20° for the M I type, and 18-20° for the M III type. Themost suitable rotational speed of sprinkler head was from 1.5-2.0rpm for the M I type, and 1.0-1.2rpm for the M III type.
The adhesion of the chemical solution which was sprayed from the miniature and high pressuretype sprinkler with a turbine system was less on the back of leaves. However, it was improved bynozzle size and spraying method at intermediate pressure.
Attaching a wire gauze to the sprinkler head was effective in keeping within the boundary of grove, and it was also effective in improving adhesion rate of the chemical solution onto the crown.

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An investigation was made on the ultimate bearing capacity of deep circular foundations in undrained saturated clay, theoretically and experimentally.
The slip-line fields around two-dimensional model foundations with various kinds of cross sections under vertical loading were observed. When there was movable space of the soil mass between the-foundation side and the ground, like foundations constructed on the bottom of a slope and cones penetrating into the ground, etc., the slip-line fields were found to be the ones in which slip-lines reached the foundation side as Meyerhof had assumed.
However, when there was no movable space of soil mass, like deep foundations and piles, the slipline fields were done to be the one in which slip-lines reached still the ground surface different from Meyerhof's assumption.
The slip-line fields around circular deep foundations in clay were analyzed three-dimensionally under the condition of axi-symmetry, using the observation results and the slip-line fields with the intermediate transient region used for calculating the earth pressure of a broken-back retaining wall by Sokolovsky. The analysis was made under the assumption that the soil was perfectly plastic-rigid and stress fields was satisfied Haar-von Karman's condition.
The results of analysis were expressed as the bearing capacity factors (N_c) in terms of the ratio of depth/width of foundations (D_p/2 R). The in-situ test results obtained earlier were found to agree well with the theoretical bearing capacity factors.

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Many earth dams for irrigation have been built in Japan. Since most of small earth dams were constructed only on the basis of empirical technics, the soil engineering properties of the dams' bodies and foundation ground were not investigated for the most part.
These properties are considered to be very important to provide a reasonable estimation of the safety of earth dams during an earthquake. It is very important in practice use to estimate the soil engineering properties using such soil parameters as soil classification, degree of compaction and N value by the standard penetration test which can be determined easily.
For this purpose, in situ tests (standard penetration test, PS logging, density logging) and laboratory tests (compaction test, permeability test, compression triaxial test, cyclic triaxial test) were carried out for about 34 earth dams which were damaged by the 1983 Mid Japan-Sea Earthquake in both Aomori and Akita Prefecture.
The relationship between the in-situ test parameters and the labolatory test parameters such as the permeability, shear strength (C', φ') and dynamic mechnical properties (deformation charactaristic, liquefaction strength) were determined using these investigations.

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Runoff analysis for actual usage requires that a runoff model should be constructed at anyplace discharge data are measured, even so, the data are good or bad. If a model is strong for these bad data, the model is called ‘robust’. This paper proposes a new runoff analysis method, the RFMD method, using the robust multiple regression analysis. The method uses the Biweight method of the M estimation method. A new concept, RFMD, is introduced according to FMD. The method was applied to the Lies 21 km² dam basin in Yamagata Prefecture. This method gave good results in estimating the discharge. With a comparison with the FMD method, the RFMD method can give similar accuracy as the FMD method, but robustness in much stronger. For separation of the linear runoff, a component of linear runoff of the RFMD method is more independent to RFMD than that of the FMD method. From this point, the RFMD method is superior to the FMD method.

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In general, unconfined compression strength is used for stability analysis of soft ground. It is well known that this parameter has a large variability (uncertainty and randomness). The reliability analysis method is used to consider this variability. In this study, this probabilistic method is applied to the stability analysis of soft ground under a preloading embankment.
When stability of soft ground is analyzed, it is often thought that undrained shear strength increases with the consolidation process. The ground discussed in this paper can be assumed to consist of normally consolidated aged clay layers. In this case, not only undrained shear strength but also consolidation yield stress is needed to calculate the strength incease. These parameters were treated as random variables in this paper.
First, a statistical model of the undrained shear strength and that of consolidation yield stress were defined on the basis of the laboratory tests (unconfined compression test, oedometer test) and as a result of undisturbed soil samples. Then, it was calculated using the Monte Carlo simulation method, the transition of spatial distribution of undrained shear strength with consolidation process. Finally, the φ_u=0 reliability analysis was carried out and stability of the ground was estimated by reliability index β. In conclusion, the effect of strength increase on stability of the ground could be known.

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It is well known that many oxidation ditches have shown a high degree of denitrification. To remove nitrogen, many operation systems of the oxidation ditch have been proposed and used at sewage treatment plants. However, few plants have used falling water as an aerator. In an oxidation ditch, falling water is effectively used as an aerator. The oxidation ditch method applying falling water is as efficient as any other method.
In this paper, intermittent aeration in an oxidation ditch using falling water was investigated for the purpose of removing nitrogen. In this ditch, a pump was used for lifting the water. The intermittent aeration was carried out by on-off operation of the pump.
The experiments of removing nitrogen using this ditch was carried out during November, 1989 and March, 1990. As a result, it was found that a high rate removal of nitrogen was obtained constantly during a mixed liquid temperature below 15°C. When the temperature was above 15°C, higher than 95% of BOD removal ratio and 90% of nitrogen removal ratio were achieved at the same time. The optimum operation for removing nitrogen was carried out under intermittent aeration by 30 min of aeration and 60 min nonaeration as one cycle. In this case, denitrification was achieved during 30-60 min of nonaeration period and nitrification-denitrification processes of activated sludge were effectively accomplished. In the oxidation ditch method, the aerator applying falling water was also effective in removing nitrogen.

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[in Japanese]

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