Abstract
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.
