Over 20 years have passed after beginning of RCD research, and over 15 RCD projects have built or are under construction. On the other side, RCC has been applied to many dams and other projects. Outlines of these two constrution methods have pesented in ICOLD Bulletin 75 “Roller Compacted Concrete for Gravity Dams”- State of the Art. However, technical manuals or other detailed technical reports have been published in only Japan and United States.
A way of thinking about design proportion of extremly dry concrete and the difference between RCD method and RCC method are described in this report. It is expected to contribute to the development of the concrete dam construction.

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Control of cracks caused by the heat of hydration is one of the most important research themes in the design and construction of mass concrete structures such as dams from the view point of functions and durability of structures.
Low heat type cement, embedded pipe cooling and precooling are commonly used for controlling thermal cracks of concrete dams.
This paper discusses about the methodology and applications of precooling usin -196°C liquid nitrogen through the investigations upon the actual uses in Japan and other countries. The effect of precooling is also presented.

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In recent years, many gravity dams are constructed on weak rock foundations. But until now, as to weak rocks, there are few standardized methods to evaluate the engineering properties of rock masses as dam foundations.
In weak rocks, it's very useful to measure the strength of rock specimens for evaluating some engineering properties of rock masses, because they have an intimate relation to those of rock specimens relative to hard rocks.
Needle penetration test is one of the most avaiable methods to evaluate the hardness of weak rocks. As a field evidence, needle penetration gradient (or strength: Np[kgf/mm]) has a well correlation to uniaxial compressive strength. For this reason, it is recognized Np will be a possible indicator of strengh of weak rocks.
But in some cases, needle can't penetrate into rocks. In other words, needle penetration test isn't applicable to following rocks.
1) Th rocks, its grain size is greater than coarse size.
2) The rocks, its uniaxial compressive strength is higher than 100-150kgf/cm² (≅10-15MPa).

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Since the water flowing into the Agigawa Dam has a relatively high concentration of nutrient salts and eutrophication of the reservoir is worried about, the several measures are investigated for conserving the water quality in the reservoir. In the catchment area, efforts to reduce the nutrient load are made through measures such as construction of public sewage systems implemented by the cooperation of the local governmental agencies.
As regards the water flowing into the reservoir, the suspended nutrient salts are removed by precipitation using a storage dam, and a pipeline was installed between the point of inflow and the intake tower to reduce the duration of time the nutrient level of the reservoir. In the reservoir, the fountain has been installed with the aim of deactivation, and hypolimnetic aeration equipment has been installed to prevent the generation of hydrogen sulphide and the elution of minerals. The implementation of these measures is expected to have a considerable eff ect in improving the water quality of the Agigawa Dam Reservoir, where the operations started in April 1991, We will conduct verification and evaluation of these measures.

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The 3-Dimensional automatic Remote Surveying System has been developed for automatic surverying in big sites.
Ordinary surveying requires at least two surveyors. The new system, However, enables a single surveyor to conduct field surverying. All he has to do is just to bring “an intelligent pole”, which is an electronic instrument as a moving target, with him. And a 3-dimensional autotracking surveying machine equipped with a servo unit which permits automatic motorized rotation of the alidade and the telescope in the horizontal and vertical directions, which has been designed mainly for execution of dynamic positioning of moving objects, always tracks the intelligent pole and collects its positioning data. Operating from the pole, He can easily make sure of the survey results transmitted from the station in real time, at the site.
Through the radio and cable multi-network system, all the collected data are put into data bases instantly. These data bases help users with doing all the series of survey works such as drawing, calculation and the other things highly effective and efficiently.
In terms of the automation in construction sites, I think that the automatic positionig technique is one of the most essential one. The completion of this 3-Dimensional Automatic remote system could contribute to the coming out of automatic sites' robots in the near future.

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