Seepage behavior of drainage zoning in a concrete faced gravel-fill dam via centrifuge and numerical modeling

Sandy gravel materials have recently been utilized in place of crushed rock materials as the main rockfill materials in Concrete Faced Rockfill Dams (CRFD) to address geological and environmental problems. In this paper, an experimental scheme for centrifuge modeling was developed to simulate a Concrete Faced Gravel-fill Dam (CFGD). The dam considered in this study was designed to implement a drainage zone of high permeability in the main gravel-fill zone to enhance safety against accidental water infiltration into the dam. Two centrifuge tests were performed and compared to investigate the performance of the drainage zone. The first test was done with the drainage zone and the second without the drainage zone. In the centrifuge tests, water infiltration was simulated by raising the water table over pre-implemented cracks on the model face slab. The infiltration behaviors were monitored by pore water pressure transducers. The centrifuge tests showed that the drainage zone of the CFGD effectively drains infiltrating water out of the dam body in a short time. Numerical modeling was also performed to help understand the process of seepage through cracks.