Abstract: Excess pore water pressure will be generated in the core during the construction of high rockfill dam, and it dissipates slowly. After water storage, the core will change the unsteady seepage state to the steady flow state; so the seepage characteristics are very complicated. The pore water pressure generated during construction can not be considered in the finite element method for seepage calculation; and the seepage characteristics of earth-rock dam can not be fully understood. Changhe Dam is a gravelly soil core rockfill dam, with maximum height of 240 m. Centrifuge modeling tests are carried out to study the seepage characteristics of Changhe Dam through analyzing the generation and dissipation of pore water pressure in construction and operation periods. Test results show that the pore water pressure would go through periods of generation in the construction, the dissipation after construction, the generation and dissipation in the unsteady seepage state, the stabilization in the steady seepage state. The pore water pressure and duration of each period are influenced by the position and filling water content of the core. The higher the position or filling water content of the core is, the larger the coefficient of pore water pressure during construction is, the shorter the duration of steady seepage is. The higher the position or smaller filling water content is, the larger the potential is. The potential in unsteady seepage state is larger than that in steady seepage state. It is instructive for design and construction of high core rockfill dam.

Key words: high core rockfill dam, pore water pressure, seepage characteristics, water content, centrifugal model test