Recently,　fruitful　results　of　geotechnical　problems　solved　by　the　NMM　(abbreviated　form　for　the　numerical　manifold　method)　have　been　gained.　In　the　present　work,　a　free　surface　updating　strategy　is　implemented　into　the　NMM　to　simulate　unconfined　seepage　flow　in　the　soil-rock　mixtures　(SRMs).　Several　examples　are　employed　to　validate　the　effectiveness　and　correctness　of　the　proposed　numerical　model.　Results　from　the　numerical　examples　indicate　that　the　proposed　model　can　predict　the　location　of　free　surface　with　high　accuracy,　as　well　as　capture　the　main　feature　of　the　unconfined　seepage　flow.　In　addition,　the　influence　of　rock　blocks　on　the　seepage　flow　in　the　SRMs　can　be　captured.