Strong earthquake shaking may cause cracking of concrete gravity dams and threaten safety of the dams. Hence, possible cracking of a dam body must be studied carefully. In this paper, a coupled FE-BE method is developed for nonlinear dynamic analysis of a dam-reservoir system with rigid foundation. The possible cracking of a concrete gravity dam under intense ground shaking is analyzed to find effects of dam-reservoir interaction and added mass technique on the cracking of dam body, followed by discussion on effects of reinforcing bars on reducing the earthquakeinduced cracking. Through these, the present method is proved its validity.

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Selective intake facilities are equipped on many dams for water quality management, by which the water can be taken selectively from the required layer of water quality. In the past intake form of opening and closing of gate valve, the frequent maintenance and repair works make it complicated for the dam management. In this study, a GATELESS intake structure of multi-hole type is researched from the viewpoint of easy maintenance. In stead of the intake gate, the air valves by supplying/exhausing compression of the air is developed and the technological consideration is carried out with this intake structure.

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A new aseismatic asphalt mixture suitable for underwater construction has been developed, to be used for thin facing or lining of dams and other large-scale hydraulic structures. This mixture possesses sufficient fluidity for uniform spreading over specified area, even underwater. Furthermore, the hardened (in a room temperature) mixture would remain stable under large seismic load due to its elasticity similar to rubber, and would exhibit excellent water-tightnessand durability owing its compact molecular structure. The mixture consists of aggregates, fillers, and a special comprising mainly of bitumen. Tire chips were used as an aggregate to enable conservation of resources. A special coupling agent was used to avoid separation of the chips from the binder, and a viscosity reducing agent was used to lower manufacturing temperature approximately 30°C below the normal figure. As such, CO₂ generated during production (hot mixing) is much less than usual. Since the spreading temperature of the mixture is below 100°C, safe underwater construction is possible. In addition, cost is reduced because of shorter construction period resulting from the thin working thickness (approximately 30mm). More than 25 years have passed since construction of most of the large-scale hydraulic structures in Japan, and they are awaiting extensive repair works. In addition to water-tightness, seismic resistivity is indispensable for repairing materials used in Japan where earthquakes frequently occur. The asphalt mixture developed for the study enables safe and prompt repair works through a totally new construction method taking into account seismic resistivity and environmental conservation, to be used even during services of dams.

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It is quite important to establish a technique to predict precipitation with high accuracy for next five hours, in order to properly manage and operate a dam. The statistical analysis based on the existing meteorological data as well as the observation at the site using Doppler radar allowed us to obtain necessary data and information for development of the precipitation prediction technique. We conducted the analysis of the precipitation specifications in the vicinity of the dam based on these research results, and developed the precipitation prediction technique with high accuracy for next five hours.

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The RCD construction method is safe, quick, and low-cost method of constructing dams based on dam-construction machines and rational methods. Discharge facilities and control facilities must to be built inside a dam, so short period of time and proper installation of these facilities are indispensable for rational dam construction. A case study is presented in which a manufacturer of discharge facilities and a dam constructor cooperated to quickly build dam facilities using the advantages of the RCD construction method.

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