To properly construct impermeable embankment, typically the core zone of rock-fill dam, it is required to ensure a sufficiently low hydraulic conductivity, in addition to sufficiently high strength. To this end, the grading characteristic and moisture content, w, of fill material are controlled and the w value and dry density of compacted soil are measured and controlled. Conventionally, the compaction is controlled by lower limit management of the degree of compaction, Dc, and upper and lower limit management of w. In this method, however, it is difficult to efficiently exclude poor-quality compaction while facilitating high-quality compaction. To solve these problems for the construction of a 139 m-high Koishiwaragawa dam, a series of laboratory and test filling was performed at various compaction energy levels, soil types, and w values. It was confirmed that the compaction becomes more efficient by implementing a relevant lower bound control of the saturation degree, Sr, together with the control of w and Dc specified based on the Sr control. The quality control record during the dam construction showed that the new method could achieve sufficiently high quality of embankment, even higher than a number of previous similar rock-fill dams.
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