Abstract: The seepage stability of high earth rockfill dam greatly depends on the protection of filter layer on core-wall material. Under impounding and long-term running conditions, the core wall undergoes complex structural load, saturation and water effects. Being affected by differential settlement, complex structural stress, hydraulic fracturing and seepage flow, the core wall when cracks formed will meet severe situations for seepage stability and filter layer of protection. To solve above problems, reverse filtration tests on unconventional filling material and slurry were designed to simulate the scouring and blocking of the particles under the cracking of the core wall by the reverse filter material and the deposition process in the crack. The results show that core wall particles are intercepted and deposited on the upstream surface of the filter layer. The filter material can effectively prevent the loss of clay particles. When the core-wall material and the filter material meet the filter criterion, the filter layer can still effectively protect the core-wall material under extreme conditions.

Key words: earth core wall dam, core-wall material slurry, seepage test, filter protection test