This thesis examined the reproducing for realities of the residual pore water pressure which I analyzed residual behavior of groundwater of the reservoir limb landslide with drawdown of reservoir level, and worked out admeasurement technique to get residual rate of residual pore water pressure rationaly. Taking into account these rearities, I worked out permeability property of reservoir limb landslide in every geological feature by seepage flow analysis of converse calculation, and next, use this permeability property, I calculated residual rate of pore water pressure which met reservoir drawdown rapidity. In addition, I overwhelmed course of landslide and showed the residual rate which met reservoir drawdown rapidity, permeability of a lump of clay. We can set residual rate of residual pore water pressure to use for stability analysis by these disputation adequately.

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Kyushu Electric Power Co. is constructing the Omarugawa pure pumped-storage power station, which includes an upper regulating reservoir covered with the whole asphalt-concrete facing. This reservoir is composed of high embankment of rock fill materials and excavated rock masses overlain by asphalt-facing. In order to evaluate its seismic safety, general tendencies of dynamic characteristics and places with maximum strain were firstly grasped by 3 D dynamic analyses of the whole regulating reservoir model for inputting earthquake motion with the effect of the site. Then, a series of 2 D dynamic analyses were carried out in detail and the maximum strain of the asphalt-concrete is determined. These analyses were reported in past. In this study, the structural safety of the regulating reservoir was evaluated by comparing the analyzed strain with the experimental failure one for the asphalt-concrete.

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In order to quantify the water quality improvement method by direct removal of the biomass of Phragmites australis which accumulates nutrient salts, the biomass of Phragmites australis under various temperature curve and daily global radiant flux were analyzed and the nutrient content were calculated. The variation of the biomass was related to the total accumulated temperature of early growing season by stored material of rhizomes and of photosynthetically growing season, and the ratio of the respective accumulated temperature. Analysis of annual flux showed that the respiration of aboveground and belowground plant organs was an unavoidable component and changed the energy budget of utilizing photosysthesized materials, caused the variaiton of the biomass. The removable quantity of nutrients of aboveground biomass was changed drastically with respect to the harvest day

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In Japan, there are many concrete gravity dams designed to be constructed on soft rock foundation. In these cases, because shear resistance of a dam foundation does not satisfy a safety condition against sliding, it is necessary to enlarge a dam body to increase shear resistance; a fillet or a foundation treatment with base mat concrete is generally constructed. On the other hand, a replacement method using artificial materials is suggested to improve a soft rock foundation entirely. In this method, a soft rock foundation is replaced by an artificial material, such as a poor mixed concrete or so on, to improve a shear resistance. Furthermore, the stress occurred in a soft rock foundation is dispersed by a foundation replacement; the stress concentration that usually appears at the toe of a concrete dam is lowered. To use this method practically, it is necessary to develop a design method of the foundation replacement. In this study, it is clarified that the effects of shape and size of foundation replacements on an improvement of shear resistance of a soft rock foundation by model tests and numerical analyses.

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Many experimental studies show that some gates suffer self oscillating vibration under the submerged flow condition. There however seems no analytical study investigating the reason why the vibrations occur. Authors present numerical analysis study on flow pattern when the gate oscillates in flow. Navier-Stokes equation was solved by iteration where the gate model mesh moves periodically in flow. Flow pattern obtained here indicates that hydraulic excitation force or damping force from flow is induced by periodical vortex flow under the gate.

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Filter materials are required to be cohesionless. At present, from this point of view, we have the criterion that the percentage of the soil passing the #200 sieve should be less than 5%. However we can use any soil for filters, if we can confirm their high permeability and non-cohesion. We have performed Sand Castle tests proposed by P. Vaughan in order to confirm non-cohesion of filter materials. In addition, we have discussed the method of relaxing restrictions on the percentage finer than the #200 sieve of filter materials for embankment dams.

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