Abstract: Concrete-rockfill combination dam (CRC dam) is composed of concrete wall, rockfill, cushion layer and transition layer. As a new structural pattern, its stress and deformation characteristics are not studied thoroughly. For this reason, a model test is carried out to measure the earth pressure and displacement of CRC dam on alluvium deposit at different heights and to explore the performance of CRC dam in filling and impoundment stage. Then a modified calculation method of earth pressure considering the displacement is proposed. The test result shows that: the rockfill is close to active state at the end of dam filling construction, the earth pressure on the concrete wall is relatively low, while the rockfill is close to static state under the water pressure at the end of impoundment stage, the earth pressure on the concrete wall is approximately one time higher than that of the filling stage. The modified formula well reflects the change rule of the earth pressure with wall displacement during filling and impoundment stage. The minimum of sliding safety factor (SSF) occurs at the end of dam filling period and meets the relevant requirements. The test proves that the CRC dam has good adaptability to alluvium deposit.

Key words: concrete-rockfill combination dam, model test, earth pressure, stability, alluvium deposit