Laboratory investigation of seepage coefficient through crushed-rock dams

ABSTRACT The importance of investigating flow behaviour through porous structures lies in indicating the amount of energy dissipation through the spillway. In the present work, a laboratory study was conducted in order to study the variability of the hydraulic gradient and seepage coefficient of a spillway constructed from crushed rocks of different gradations under different flow conditions. Four different models of rock spillway are used with different grain sizes under a constant height. The results show that the values of the turbulent seepage coefficient for the models used range between 13 and 49 cm/s. Even though the models with minimum and moderate grain sizes (d50 of 27 and 30 mm) should have high porosity, the water flows more slowly than with other given sizes. The maximum effective diameter used in the study results in the highest seepage coefficient. As a result, at a constant flow condition, the grain size directly affects the flow behaviour through the spillway.