水位急低下時の堤体内浸透挙動に関する遠心実験

Abstract

Embankment dams for power generation and irrigation purposes have often experienced severe damages of slope failure due to a rapid draw-down of the reservoir water in seasons of full operation. This paper concerns seepage behavior in embankment dam during a rapid draw-down of the reservoir water. Distribution of the residual pore water pressure generated in the dam body and its influence on instability of the upstream slope are important points to be discussed. Centrifuge model tests were carried out on several model fills with different permeability, by varying the decreasing rate of the reservoir level, to understand the mechanism of seepage flow during draw-down and variation with time of the residual pore water pressure accumulated in the embankment. Sliding failure of the upstream slope was also realized in the tests to discuss an appropriate procedure of evaluating the residual pore water pressure and its influence on slope stability. The test results and associated analysis of slope stability revealed that the residual pore water pressure generated during rapid draw-down directly leads to a serious damage of the upstream slope, and the procedure of pore water pressure estimation currently adopted in the design gives a safe side value as compared with the tests results.