With regard to multi-purpose dam operations during floods, delayed operations and excess impoundment over the normal water revel are occasionally reported since there are no applicable rules when the reservoir water level is very low below the normal water revel in a summer flood season. In order to prevent such risks on a necessary flood control operation and improve its function, adjustment operations based on the water level threshold discharge method may be effective. This paper verifies the effectiveness of the method with past flood data and propose further improvement plan in order to minimize the risks such as rising speed of the downstream river water level.

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KIDO Dam is a gravity concrete dam with about 500,000m³ volume of the bank in Fukushima Prefecture. In this construction, JIOCE mixer was adopted as mixing the RCD concrete for the first time in Japan. Moreover, it is improved the efficiency of dam concrete construction by the automation system of the cable crane applies in temporary facilities of the dam, the precast formwork was applied positively for the gallery and the other structures in the dam, as result the rationalization of construction was executed. In this report, it is described construction experience including the quality of the RCD concrete by JIOCE mixer in this construction, the automation system of the cable crane, and a precast formwork and so on.

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This paper are discussed the liquefaction-proof design of aged embankment dam rehabilitation referring to the construction of new embankment dams with liquefaction-proof zoning pattern. The Zoning pattern for rehabilitation to prevent the liquefaction of the aged embankment dam, is basic technique that the shell zones are constructed to applied the counterweight on the upstream and downstream slopes of the old embankment, and filter zones were constructed to dissipate the excess pore pressure generating in the old embankment during earthquake.

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