Most of slopes of levee made by land consolidation may often be wide at a steep sloping area.Therefore, the work for weeding should be difficult in terms of the shortage of labor and the advanced age of farmers.
In the present paper, we investigated on the paddy field, in which land consolidation has been achieved, to clarify the form of weeding levee and the present condition of weeding work. Results obtained are as follows:
1) The levee slope tends to make steep sloping parts in order to be reduced unusable land.
2) As heavy labor by using power grass cutter needs for weeding work, farmers are used to devise various methods to lighten the work.But some farmers should stop the levee weeding work due to their heavy labor.
3) The weeding work varies with method and the part on the slope of levee.As the trim-up method which needs heavy labor is adopted at the slope toe, worker's physical burden may inevitably increase.It may be expected the countermeasure to lighten for weeding work at the slope which is needed heavy labor, especially at the toe of the slope.

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Accidents in weeding work sometimes occur seriously by using the power grass cutter on paddy field in a steep sloping area. In the present paper, we examined danger in weeding work and the farmer's measures.We indicated the necessity to set berm at the levee slope and proposed the form and the arrangement of levee slope for safe and efficient weeding work.
Results and considerations are as follows:
1) The safety and efficiency in weeding work has been desired by farmers, however, safety measure was not fully established.Some farmers take the measure to set a step on the levee slope.
2) To make gentle sloping and to set berm have been desired for the design of levee slope. However, its design has not much been taken practical use because of increasing unusable land.
3) To set berm is very important for safe and efficient weeding work, so, we proposed the berm form reducing unusable land, and devised to set berm form both at the middle of the slope and slope toe.

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There are two ways to weed levee efficiently by improving farm land consolidation technique.One is to reduce weeding area, and the other is to form the farm shape suitable to weeding.In this paper, by model simulation on relation between field shape and weeding area, we examined the former from the following two points of view.(1) Area of levee and it's slope.(2) Length of road and drainage canal.
The results are as follows.
1) Making paddy field lot horizontally wide is effective for reduction of weeding area the tendency grow stronger in sloping lands.
2) For the purpose of shortening road and canal length, horizontally wide lot is effective too.
3) The “Counter Form”farm land consolidation type which we have been proposed is also effective to reduction of weeding area.

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There are two ways to weed levee efficiently by improving farm land consolidation technique.One is to reduce weeding area, the other is to form the farm shape suitable to weeding. In this paper, we mainly examined the latter-the former in the 4th paper of this series.
We took notice of the fact that the shape of drainage canal and levee has considerable influence on efficiency of levee weeding.And, we examined on the relationship between weeding labor and the shape.
The results are as follows.
1) Whole surface lining or underground laying of drainage canal is of great help for efficiency of weeding labor.
2) These method of construction have different adoptive conditions.So, we arranged the conditions and described elementary items.
3) The “Counter Form”farm land consolidation type which we have proposed is also effective to reduction of weeding labor.

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This study is to explicate an analysis of residents' opinions and sense for the improvement of river environment in rural areas.We conducted a questionnaire on the residents using six simulation models which were made on the basis of a picture of Iu River of Yakumo Village in Shimane Prefecture by computer image processing.Fifteen bipolar adjective phrases that express the emotion of river environment such as natural or artificial feeling, good or poor harmonious feeling were determined.The mean values of evaluation of these adjective phrases related to each improvement plan of river were calculated with Semantic-Differential method on the basis of questionnaire for the residents.
As a result of analysis, the following became clear.There are significant regional differences in the importance of the functions of river such as flood control, water utilization, water amenity and environmental preservation.And, two common factors, Comfortableness-factor and Activity-factor, determining emotional evaluation of river environment were chosen based on the factor-loadings of the adjective phrases which were obtained by the factor analysis method.The improvement plans of river, using not concrete or stone wall but vegetable materials such as lawn, are highly rated in each local groups of investigated rural areas.But, there are regional differences in evaluation of the improvement plan of river in case of setting up playthings easily in riverside or covering bank protection with stonewall, even if the river is improved with lawn.

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The loading process of pollutants and inorganic ions from a paddy field was observed on nine occasions caused by rainfalls of 14-38mm in depth during a non-planting period from 14 September, 1991 to 14 May, 1992 (243 days).The water samples were collected in a small weir which was placed at the outlet of the paddy field (2, 070m², soil infiltrability: 1.3×10^-1mm·h^-1) to measure the volume of discharges.Precipitation and dry fallout were deposited and then collected once a month to estimate the amounts of the external supply of the materials.
The first drop from the weir occured, on the average, after a precipitation of 3.5mm.Before the surface soil of the paddy was plowed, the highest concentrations of SS, TCOD_Mn., TN and TP containing particulate constituents were found in the first outflow of the discharge, followed by a gradual decrease.After the plowing, the profiles of the pollutographs showed a similar tendency, but the concentrations became several times higher than those shown during the non-plowing period and reached at the maximum around the peak of the hydrograph.Correlations between the surface loading of the materials Lsi and the amount of the corresponding rainfall Ri were found to give the following E_q., L_si=a (Ri-r) ^b, where a, b were coefficients calculated by the least squares method.γ(=3.5 in this case) was the depth of the rainfall which did not cause surface discharge because of percolation.Values of a and b for TCOD_Mn, TN, TP and NO₃-N calculated from the data obtained before the plowing differed from those after.From the equations and the data of the rainfalls during the non-planting period, the runoff loadings of TCOD_Mn, TN, TP and K⁺ for the period were calculated as 62.6, 14.4, 3.37 and 37.4 kg·ha^-1, respectively.These values were as large as 2.38, 1.29, 7.12 and 17.0 times, respectively, of the external supply from the precipitation and the dry fallout during the same period.

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According to the standard specifications of the structures being constructed on saturated loose sand ground such as drainage pumping ones, the FL value, the factor of safety against liquefaction defined by the ratio of dynamic shear strength to cyclic shear stress, is adopted as the judgement of liquefaction when earthquake occurs.In addition, it is recommended that the maximum ground acceleration value is employed to estimate the cyclic shear stresses in soil deposit.
In this paper, the authors conduct the probabilistic liquefaction analysis introducing the distributions of annual largest acceleration values obtained from historical seismicity data in the liquefied site at Niigata Earthquake, Kawagishi in Niigata City.Furthermore, we calculate the optimum values in case of the construction methods of heaping up soils and SCP for preventing liquefaction with the aid of the minimum cost criterion.In conclusion, it is shown that the optimum values are determined by nothing but the cost index which is related to the degree of importance of the structure.

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The mechanical behaviour of a single cell grain storage silo under non?axisymmetric loads such as wind and seismic forces was investigated.The study was carried out by the use of finite element method (FEM) incorporating planar elements which are transformed into shell elements.The representation of the non?axisymmetrical loading on a selected silo model shell wall has been illustrated.Further, some of the generated deformations and internal stresses based on the developed procedure and adopted reference wind velocity of 35m/s and seismic coefficients of 0.339 (for silo body), and 0.281 (for stored content) which are consistent with the suggestions given in the JSAE standard codes have been presented.
The generated deformation and stresses due to the non-axisymmetrical loading on silo in use were compared to those of the normal state silo.From the results it was found that these loading induced large deformation and stresses on the silo wall, for example, wind generated maximum bending moment was about 1.4 times more than that due to normal state silo.Likewise, seismic force generated higher value of about 3 and 2 times of the normal state and wind load respectively.

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It is important to investigate thoroughly the change in long-term runoff properties due to land reclamation.Rainfall-outflow records for a period of 12 years, from 1980 to 1991, have been collected for two adjacent catchment areas, namely A and B, at Gojo Yoshino area of the Nara Prefecture.Catchment A is a reclaimed farmland area, while catchment B is a natural forest.The method of ‘paired watershed’ was used to analyze the long-term runoff properties in terms of outflow hydrograph, outflow duration curve, and runoff ratio.
For the summer period characterized by scanty rainfall, the results obtained showed a higher value of total runoff discharge for catchment A.Outflow duration curves for the two catchments showed that the previous finding is valid for outflow depth less than about 0.5mm/d.The difference in runoff ratios for both catchments, during irrigation periods, expressed in terms of water losses was found to be about 112 mm, which was mostly seemed to be attributed to the difference in evapotranspiration.
The results proved that the scanty runoff from the reclaimed farmland is more than that from the adjacent forest; that is, the forest does not play a role in increasing the scanty runoff in this case.

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It is important to use conformable constitutive model and the parameters for fiel condition, when designing or analyzing soil structure and ground stability.Therefore, it is necessary to determine the model and the parameters from soil testing, which represent the stress and deformation conditions at field precisely.Considered from field conditions, not a few structures and grounds are under plane strain condition, and, two?dimensional analyzing model, that is, plane strain model are often used for computer calculating.And recently, more attention are payed to estimate the deformation and strength characteristics of clay which construct soil structures and grounds.
In such a present circumstances, soil performance under plane strain condition is considered to be predicted more exactly.In this paper, strength and deformation characteristics of clay under plane strain condition are investigated.Firstly, from the results of undrained static shear of K₀-consolidated kaolin, some essential characteristics of clayey soils are investigated, and compared them with sandy soils.
From the test result, it is revealed that the development of pore water pressure and intermediate principal stress are different from sandy soil, while some essential characteristics of K₀-consolidated clay is confirmed, that is to say, there is a certain relation between K₀ andφ[= arcsin ((σ1-σ₃)/(σ₁+σ₃))] values, and the shear strain at the peak strength is very small. Furthermore, it is clarified that coefficient of intermediate principal stress (i.e.b value) results in a constant value, instead of the different conditions of testing, for example, preconsolidation history and drained condition and so on.And from the result of conventional triaxial test, the method of estimating plane strain strength at critical state is proposed.It is found that the proposal method can explain the test results very well.

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Runoff and water budget changes due to farm land reclamation are discussed on the basis of observed data for 8 water years from 1981 through 1988 at two experimental catchments A and B in Wajima-Yanagida district, Ishikawa Prefecture.The catchment A of 11.0 ha was reclaimed in 1979 to use it as an orchard farm.And the catchment B of 14.7 ha located near the catchment A is remained as a forest land yet.In this paper, the comparison of runoff and water budget characteristics of those two catchments is carried out.The results obtained are summarized as follows:
(1) By farm land reclamation, the time of flood concentration shortens considerably, the retention capacity of rainwater of the catchment decreases slightly, and the peak discharge of flood increases.
(2) Daily runoff hydrographs and flow-duration curves of both catchments show that the low-water flow in the drought period decreases obviously by reclamation.
(3) The ratios of actual evapotranspiration to evaporation from water surface are 0.71 in catchment A and 0.78 in catchment B, respectively.That is, the evapotranspiration decreases a little after the reclamation.
(4) The changes of runoff ratio reveal that the annual runoff volume increases slightly.The change of evapotranspiration may become one reason for those runoff changes.

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The Long and Short Terms Runoff Model (LST Model) is applied to two experimental catchments of reclaimed farm land and forest, both located in Wajima-Yanagida district, Ishikawa Prefecture, on the basis of observed data for 8 water years from 1981 through 1988. The data for the last 4 years, in which the data have been recorded without rest even in winter season, are used for the identification of model parameters.Then all data for 8 years are used for the verification of identified models.The results obtained are summarized as follows:
(1) The simulated hydrographs show good agreement with the observed ones in both catchments. It can be concluded that the model explains well the runoff changes due to land reclamation.
(2) The model parameter changes due to reclamation are found only upon the ones of upper tank corresponding to the prompt runoff.That is, the runoff changes due to reclamation are mainly governed by the surface layer changes.
(3) The annual mean water budget for 8 years estimated by the model shows that the total runoff volume increases slightly due to changes of evapotranspiration, and the groundwater runoff volume decreases due to changes of distribution of runoff components after the reclamation.

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In order to obtain a satisfactory result, the author has been conducting “Experimental Research on the Reclamation of Junsai Paddy Fields” since 1976, and illustrates his explanation by citing examples of fields reclaimed and swamps where water shields have naturally developed. These results have made it possible to write specifications for those fields.This report aims to consider how such test fields are reclaimed on the basis of the specifications, with special regard to the actual work taken.The actual yield was also examined.The results may be summarized as follows:
1) The test fields are reclaimed in a such manner that their cultivation might be simplified as much as possible.Table 1 shows the overall construction system, the construction order, the material quantities and the specifications.Reclamation of the fields is made roughly in accordance with the specifications as shown in Table 1.It was also found that there is much wasted time and labor in the conventional reclamation method because the builder can use his discretion in choosing the specifications;
2) Medium size swamp bulldozers and swamp backhoes are generally used to reclaim Junsai paddy fields.Fig.3 has been drawn by examining the reclamation process.The standard construction schedule given in this figure has revealed that the proper order for the standard construction schedule consists of surface soil handling, foundation work, levee work and surface soil work;
3) The completion of newly reclaimed Junsai paddy fields can be evaluated using the yield and quality of these Junsai.The actual yield from the fields for a five-year period from 1988 to 1992 is given in Table 3.The findings shown in this table reveal that it exceeds the average yield from fields throughout Akita Prefecture and in the Yamamoto District.

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Based on the questionnaire to land improvement districts under construction of land consolidation projects, the following principal component analysis are carried out.(1) 7 clusters are classified by 9 principal components.These components are the agricultural condition, land, human relations, production conditons, the agricultural structure improvement policy, non agricultural land, land use change, drawing of land use map and farmers'payments.(2) The districts which initiate projects are categorized into 3 clusters by 4 factors.These are farmers'payments, production conditions, non agricultural land and farm road construction.(3) The districts where farmers agreed to implement projects are divided into 3 clusters by 3 factors of increase of agricultural productivity, agricultural structure improvement policy and farming operations.(4) The districts where farmers disagreed to promote projects are grouped into 4 clusters by 5 factors. These are human relations, production control, agricultural conditions, disposition for substitute lots and farmers'payment.
Moreover, the causes for the farmers'disagreements in unexecuted projects are studied by means of multidimentsional quantification I.As a results, it is clear that the farmers who opposed projects have doubts on substitute lots, farming management, land reduction by disposition for substitute lots and rice cultivation control.

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The Penke Aqueduct Bridge with a span length of 30 meters over the Penke UtashinaiRiver on the Hokkai Main Canal is replaced by a new one with that of 137.4 meters.The bridge has to be completed within the non-iirrigation period.For reducing the construction period, the shifting method by which the 6, 500 tf PC continuous girder bridge assembled the year before is to be slid into place is adopted.The method, which has never been used on such a scale both at home and abroad, consists of lifting the bridge girder on 6 rails by means of 36 jacks whose bottom is capable of slipping, and anchoring the rails as they are before sliding the bridge into place with jacks in the horizontal direction.The result has revealed that this method allows those girders to successfully travel a distance of 50 meters in 3 days with the aid of advanced technology.

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[in Japanese]

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