In order to prevent cavitation damages and vibration, and to estimate load for structural design, it is nessesary to know the pressure characteristics of conduit pipes. Hydraulic model tests are executed to examine the pressure characteristics of bent circular conduits, especially to know the effects of curvature radius and refraction angle of approximated type using straight pipes. Experimental results of inside wall pressure are compared with calculation results assuming two dimensional potential flow which circulates around concentric circle, and the effect of refraction of approximated type and secondary flow generated by bent flow are cleared.

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Seepage flow in the foundation rock of dams is either in laminar flow or turbulent flow depending on opening of cracks in rock. In this paper, characteristics of seepage flow in foundation rock of dams are discussed using numerical non-linear analysis in several conditions. It is understood that distribution of flow velocity along the planned grout curtain line and the effect of grout curtain is greatly influenced by seepage flow condition.

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On dams constructed in mountainous areas, radiation can lead to rapid cooling. When the time interval between placement lifts is prolonged, there is a danger of excessive cooling, resulting in temperature stress on interior restraints and on placed lifts. This paper, through models based on observed data, shows the effect of radiative cooling on the cooling of dam surface areas. Also, in order to counteract the effect of excessive cooling on restraints between lifts, temperature stress on finished lifts can be mitigated through the use of a two-step primary cooling period.

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An experimental study was done on self compacting concrete with large maximum size of aggregate for dam construction. For self compactability, resistance to segregation and good pumpability, the mixture proportions were selected by trial batches. On the pumping test of concrete, the properties as pressure loss in pipeline were grasped. The slump flow for self compacting and homogeneous concrete was confirmed from the test of casting in a large box. The state of flow, the influence of covering time on a layer to homogeneity and the shear strength at horizontal joint were investigated on the placing test in relatively wide yard.

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Although the gradient of excavation of a large slope is generally determined in accordance with the physical properties of bedrock, no design specification taking into consideration the dimension of the slope has been drawn up so far. In addition, deformation has been observed even in some large slopes with a empirical stable gradient. Therefore, in order to clarify how the dimensions of excavation (height and gradient) affect the stress state in slopes and natural grounds, elastic analysis by two-dimensional finite element method using ten models in which the shape and physical properties are simplified was carried out. From the analysis the following findings were obtained. The larger the slope, the larger the effect due to excavation gradient on the stress state in the slope and the natural ground becomes. Furthermore, partial factor of safety shows a minimum value around right above the toe of slope. Therefore, if the bedrock is a linear elastic material and its strength is assumed, the critical-dimensions of excavation for a certain value of safety factor is given by the combination of strength of bedrock, and height and gradient of excavation. These findings correspond to the existing date obtained from the previous field studies, which enable the results of the analysis to apply to the actual cases with the use of strength of bedrock, height and gradient of slopes as parameters.

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The ground for the saddle dam at the right bank of the Yamaguchi Regulating Reservoir is strongly weathered and is broken at low injection pressure because of low critical pressure. Diaphragm wail was applied to the foundation treatment under these conditions. The report describes the construction of diaphragm wall, outlines the construction methods applied to ensure that water would not leak through the joint between the grouted area and diaphragm wall, and verifies the water tightness based on the results of a test filling of the reservoir.

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