It is well known that the mechanical properties of compacted cohesive soil varies according to the nature of the soil, moisture content, compacted energy and others related factors. The purpose of compaction is to increase the strength and decrease the permeability of the soils, and this analysis is the most important theme for stability analysis of embankments. The purpose of this study is to clarify the relationships between pF moisture properties and mechanical properties in static compacted cohesive soils.
In this expriment, volcanic ash soil (Kanto loam) and non-volcanic ash soil were used with a drying process. The testing specimen made compacted to uniform dry density at static pressure. To determine the relationships among the pF value, cohesion and internal friction angle, by pF moisture and triaxial compression tests. The main results obtained are as follows:
1) pF moisture characteristic value of volcanic ash soil may be about 4 times as great as that of the non-volcanic ash soil.
2) The stress-strain curve does not indicate peak stress at the low pF range but the phenomenon of ductility failure with creeping.
3) In the pF 4.2-4.5 range, the shape of the stress-strain curve clearly indicates peak stress, the phenomenon was a brittle fracture.
4) Furthermore, at higher pF value, the stress-strain curve was similar to that of high density sand.
5) Cohesion is greatest at pF 4.2 to 4.4, and thickness of water film was about 25 to 35 Å.
6) The relation between internal friction angle φ and the pF value in Kanto loam and Turuoka clay was semi-proportionally linear.
7) Cohesion c and internal friction angle φ with straining was influenced by the pF value.

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In this paper, the physical and chemical properties of crust-formed soil is researched from the viewpoint of both soil texture and land utilization, using four kinds of soil and four varieties of field conditions.
As a result of this research, the following three kinds of crust are recognized.
1. Depositional crust: significant differences exist in the degree of aggregation, specific surface and K concentration between the most external surface layer of soil and the following one.
2. Impacted crust: significant differences exist in the degree of aggregation and K concentration between them.
3. Chemical crust: a significant difference exists only in the K concentration between them.
Therefore, the degree of crust formation can be arranged in the ascending order, 3, 2, 1.
Further, considering some factors concerned with soil erosion, the dispersion ratio has the most significant correlation to the degree of crust formation.
From the facts described above, it is proven that the degree of crust formation can possibly be explained by comparing the degree of aggregation, specific surface, K concentration and dispersion ratio of the most external surface layer of soil with these factors of the following one.

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Regarding the continuous sub-irrigation method using low positive pressure set in porous pipe and negative pressure in soil, this study was carried out to clarify its principle, extent of water supply and infiltration state under a different pressure set and different permeability of the porous pipe. Experiments were also carried out to investigate a better way of setting the low positive pressure in porous pipe or deciding the suitable permeability of porous pipe. The results obtained under the bare soil conditions are as follows.
1) The bigger the pressure set in the porous pipe is, the more the water supply and infiltration distance tend to become larger. However, it was found that their values are not always in proportion to the magnitude of the pressure.
2) The bigger the porous pipe's permeability is, the more water supply and infiltration distance tend to become bigger. However, it was found that their values are not always in proportion to the magnitude of the permeability.
3) It was found that the water supply was dependent on the degree of the dry or wet soil condition as well as the magnitude of pressure set in the porous pipe.
4) It was considered that a greater water supply could be had by increasing pressure in the porous pipe and the use of a negative pressure for the soil in case of porous pipe having a lower permeability.

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This paper presents the results of the effect of hydro-meteorological factors' influence on irrigation water demand of rice fields, throughout the irrigation period, and additionally points out the subject, on building a forecasting system for irrigation water demand from the viewpoint of systematization of water management.
For this analysis, water management records were obtained from a study area, 1, 360 ha, located along the coast of Lake Biwa, and data of irrigation water demand was arranged on a daily basis. On the other hand, hydro-meteorological data was collected from the weather bureau in and around the study area.
Using these data, auto-correlation of daily irrigation water demand was analyzed, and then, the relationship between hydro-meteorological factors and irrigation water demand was clarified by multiple correlation analysis.
Moreover, for estimating the amount of daily average irrigation water demand, multiple regression function was studied by using hydro-meteorological factors.
Results obtained are as follows:
(1) Daily irrigation water demand does not show any peculiar auto-correlation throughout the irrigation period. However, within a day, it fluctuates due to the influence of water control by farmers in the field,
(2) Among the hydro-meteorological factors, the hours of sunshine, daily average temperature and daily rainfall especially have an influence on variations in daily average irrigation water demand throughout the irrigation period,
(3) Relationship between the above-mentioned factors and daily average irrigation water demand can be defined mathematically by a linear multiple regression equation,
(4) However, this equation does not always predict daily irrigation water demand, because fluctuations in irrigation water include factors originating from farm management practices, except for hydrometeorological factors, which can not be illustrated only by a mathematical model, such as the abovementioned equation,
(5) To forecast the irrigation water demand, a new model including the farm management practices needs to be developed.

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This paper presents the results of a study of a forecasting system to determine irrigation water demand so the existing water management system can be modified.
In recent years, the work of irrigation water management personal on large-scale rice field shows signs of improving, through the introduction of a modern water management system. However, the operation work for water supply and water distribution depends on experience and knowledge of the administrator. From this background, it is important to build up a forecasting system which can provide information on water demand on a daily basis.
According to the time series analysis of irrigation water, it has been clarified that daily variations in irrigation water demand can be estimated by using the form of the “If-then” algorithm, knowing about weather and average temperature forecasted on the day, the growing condition of rice and also information regarding water management, especially the past recorded amount of water supply.
To illustrate the “If-then” algorithm mathematically, the idea of “Fuzzy Set” was introduced as a basic concept, and then, the fuzzy variables which comprise the algorithm, that is, four judgment factors for weather, temperature, growing condition of rice and recorded water supply, and grade of regulation for water demand of today, was defined by membership function.
On building the forecasting system of water demand, the process which judges circumstances of the field from information obtained by the administrator was studied, along the structure of the “If-then” algorithm, and then, the grade of regulation for water demand was formulated by a linear multiple regression equation using the fuzzy variables regarding the judgment factors. Moreover, the system which can deal directly with fuzzy information was studied, and was verified by using irrigation water management record.
As a result, it was confimed that the forecasted value fixed from the grade of regulation for water demand showed a good correlation with the amount of irrigation water demand.

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A mathematical model was built for estimating the phosphorus percolated outflow from paddy fields in terms of operating variables such as irrigation flow rate, percolation flow rate, irrigation water quality and fertilizing. This model Consists of balance equations for surface water, soil section of slow percolated flow and quick percolated flow (Mizumiti: water paths), and rate equations for adsorption, desorption, bioturbation and other relevant rate processes.
Six experiments using lysimeters under various paddy field conditions were carried out to estimate the structure and verify validity of this model.
The proposed model could simulate phosphorus concentration in percolated water under various conditions with enough accuracy, reflecting annual changes. Stability of the model with respect to the deviation of the parameters was checked by means of a sensitivity analysis. The proposed model will be applicable to estimate phosphorus outflow in actual paddy fields with extending the boundary conditions.and the parameters to larger paddy fields.

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To study the effect of crust formation regarding land reclamation of MASA soil, some experiments were carried out. In these experiments, two boxes were filled with MASA soil and analyzed regarding several phenomena, which were the transition of soil moisture and characteristics of seepage flow with rainwater infiltration in a 10 cm deep soil layer, and the occurrence condition of surface runoff and infiltration capacity, in relation with rain intensity.
The dimensions of the boxes were 50 (L) ×40 (W) ×25 (D) cm. Soil moisture suction is measured using six tensiometers, inserted on the side at depths of 2, 5, 11 cm in both parts of the upstream and downstream as shown in Fig. 1. The boxes were sloped at 5 degrees. Adequate kinetic energy of the raindrops in the rain simulator, is about 28 J/m²·mm.
Experimental results and consideration
1) Although seepage end of rainwater is extreme shallow at a depth of 2 to 5cm, surface runoff did occur. The reason for this shallow seepage end may be to due to the crust formation due to the impact of the raindrops (volume of coarse porosity in crust was regarded as zero).
2) Value of soil moisture suction in part of the rainwater seepage were from-13 to-20 cmH₂O even at minimum. When surface runoff occur, the rough estimate of water content within soil layer (0 to 5 cm deep) did not completely saturate all the pores. Apparently, in part of the seepage at the time of surface runoff appearance, it may be an unsaturated flow. Due to this fact, it is understood qualitatively that though rain intensity is smaller than saturated hydraulic conductivity, surface runoff may occur.
3) Regarding the constant infiltration rate corresponding to constant rain intensity, constant infiltration rate (the mean value from 50 to 60 min after the start of rain) increased, as the rain intensity increased. Similarly, under continuous rain, as soon as the rain intensity began increasing, the infiltration rate began to increase. The phenomenon of infiltration rate increasing according to an increase in rain intensity, demonstrates the possibility that crust formation is not stable. This view may be regard to be very reasonable that as rain intensity increases, the change in detailed physical environment on the bare surface partially destroys crust formation.

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About 250, 000, small earthen dams for irrigation exist in Japan. Most of them were constructed a long time ago. For example, 75% of them were constructed over a 100 years ago. The safety of small earthen dam during an earthquake is not necessary enough from the recent soil engineering viewpoint. Large earthquakes in the past could have caused damage to them.
Recently, the dynamic effective stress analysis which takes into account of the increasing pore pressure have been proposed. Application of this analysis to small earthen dams is difficult in practical use due to the numerous parameters needed for the analysis.
From this reason, two practical procedures for evaluating earthquake resistance of small earthen dams were proposed in this reserch. The proposed methods are:
(1) Simplified procedure using the soil data of the dam bodies and the foundation ground
(2) The circular arc method for small earthen dams taking into account increasing pore pressure.
Those methods were applied to damaged and not damaged small earthen dams in the 1983 Mid-Japan Sea Earthquake. Allowable judgement of eathquake resistance could be obtained by the method (1). The relationship between safety and settlement at or degree of settlement crest was clarified by this method (2), and the results make it possible to evaluate the settlement at the crest.

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Interferential bed load between unsteadiness and non-equilibrium is studied on the basis of our bed load formula which has been derived in the previous report and is called ‘K·T model’ in this paper. First, the propriety of the model is verified by comparing it with the formula derived by Nakagawa and Tsujimoto based on the Eulerian stochastic model. Second, the K·T model is applied to the non-equilibrium sediment process causing a flow over a wavy bed, and the relationship between the model parameters of the K·T model and the characteristic quantities (wave number and wave height, etc.) of the wavy bed configuration is clarified. Third, the sediment process, where theunsteadiness and non-equilibrium on bed load motion are induced by an unsteady flow over the wavy bed, is analyzed using the K·T model and the linear analysis for the flow. Lastly, the numerical solutions obtained from these analyses for interferential bed load are demonstrated assuming the sedimentary wave formation in a sandy-bed stream.

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It is generally known that the stream lines of groundwater in layered soils, where the hydraulic conductivities are different from each other, refract at the interfaces of each layer. Theoretically, however, it has been proved that refraction might possibly occur in both saturated and unsaturated layered soils. These refractions may have influence on the lateral flow of water and on the anisotropy of water percolation in layered soils, resulting in differences in infiltration capacity, soil moisture retention and discharge between homogeneous soils and layered soils.
The purpose of this paper is to develop the method of visualization of stream lines in saturated and unsaturated layered soils, to verify quantitatively the theory of refraction through the visualization at the interface between different materials and to investigate the applicability of the refraction theory to the anisotropy concept in layered soils.
The stream lines were successfully visualized as shown in Table 2 and Photos. 1-8, and the refrac tion law expressed as Equation (2) was verified to be valid for both saturated and unsaturated materials.(Fig. 5). The effects of the boundary conditions on the flow of water in the soil container were checked by using the regionally defined Laplace Equation (10) as shown in Fig. 6. It was also shown that the anisotropy coefficient of layered soils presented by Zaslaysky seems to be reasonable and useful for the prediction of lateral flows of water in layered slopes.

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A two-phase model for heat conduction in porous media saturated by a single fluid is constructed. Also, it is shown that the simultaneous partial differencial equations. derived from the theory can be accurately solved by the finite element method. Furthermore, using the finite element analyses, the effects of particle size of and fluid properties in porous media on heat conduction are characteristically revealed.

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It is an important objective for Japanese irrigation engineering to establish a quick and reliable judgement method for resistibility against earthquakes of a large number of old/relatively small embankment dams., If it can.give a quantative evaluation of safety depending on the reasons of the judgement, it will be a useful guideline for engineers.
Although, nowadays analytical and constructive techniques have attained remarkable progress, stilt there is a complex and difficult procedure in getting reasonable resistibility against earthquakes regarding earthen structures. This is mainly due to the fact that resistibility is controlled by two factors: one is the seismic risk of the place of construction of the structure, and the other is the aseismatie ability proper for each structure.
From this point of view, the authors have proposed two procedures. The first is an estimation system of probabilistically expected acceleration response spectrum for any place in Japan. The second is a simple judgement system of the seismic resistibility for a given embankment dam. The former is useful for estimating the seismic risk in terms of response acceleration spectrum which is especially important during structural designing. The latter is an estimating system of the seismic resistibility for a given dam using the fuzzy deduction theory from the various construction conditions. Two deduction examples are shown, and the effectveness of the proposed methods are demonstrated.

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The major objective of this study is to clarify the characteristics of the near-bottom flow which strongly affects the resuspension and transport phenomena of sea-bottom sediment in shallow sea areas. Simultaneous measurements of the velocity near sea-bottom and the profiles of suspended sediment concentration were first made at two observation sites in the interior parts of the Ariake Sea which was chosen as the study area. Then an investigation on the characteristics of turbulence and turbulent diffusion of near-bottom flow, and sea-bottom friction was made on the basis of the data obtained.
The fluctuating velocity near the sea-bottom before and after its appearance at low tide is strongly affected by the window wave. The temporal and spatial macro-scales of eddies variate largely with time. The mean values of those in the main flow diricction are a few seconds and a few ten cm, respectively. Also, the variations in the turbulent diffusion coefficient with time are very large. The mean values of those in the main flow and vertical direction are ten cm²/s-a few ten cm²/s and one cm²/s-ten cm²/s, respectively. Further, Richardson's 4/3 power-low established between the diffusion scale and turbulent diffusion coefficient comes into existence for the near-bottom flow in the study area. The sea-bottom friction coefficient ranges from 9.0×10^-4 to 4.0×10^-2, and its mean values is 2.3×10^-3, which is almost equal to the value used commonly, i. e., 2.6×10^-3.

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The thermodynamic theory can not really be applied regarding classical plasticity theories that need yield surface and loading conditions to be assumed. However, a constitutive relation can be derived from the thermodynamic principles using Endochronic theory with singular kernels, which describes the coupling effect between deviatoric and hydrostatic behavior that contains both contraction and dilation. The derivation of the constitutive relation is possible by considering the coupling parameter contained in the definition of intrinsic time measure and a coupling term in evolutional equations for internal variables.
In this paper, by taking the triaxial compression-extensiontest of soils under drained conditions as an example, the solution of the derived stress-dilatancy relation was investigated geometrically. As a result of this consideration, it was found that the derived relation can rationally describe the behavior of compressible materials such as various types of soil or concrete. Also, the direction of future development of Endochronic theory with singular kernels was investigated on the basis of theoretical consideration.

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