An　efficient　unconfined　seepage　analysis　method　is　developed　for　analysing　fluid　flow　in　fractured　rock　mass.　The　proposed　method　discretises　both　porous　rock　matrix　(a　low　permeability　medium)　and　discrete　fracture　networks　(a　high　permeability　medium)　as　permeable　pipe　networks.　A　finite　volume　based　approach　is　used　to　determine　the　equivalent　flow　parameters　in　the　undirected　pipes　for　the　porous　rock　matrix　such　that　seepage　analysis　in　a　fractured　rock　mass　is　carried　out　in　a　consistent　mathematical　framework　which　gives　excellent　computational　accuracy　and　efficiency.　Using　an　auxiliary　boundary　method,　pipe　networks　in　the　vicinity　of　the　phreatic　surface　can　be　adapted　in　unconfined　seepage　problems.　Validated　by　finding　the　phreatic　surface　in　dam　structures,　it　has　been　found　that　the　fracture　orientation,　hydraulic　aperture,　fracture　set　number　and　fracture　distribution　can　affect　the　phreatic　surface　significantly　in　a　fractured　rock　mass.　The　proposed　method　is　applied　to　investigate　the　effectiveness　of　the　water　curtain　system　in　a　water-sealed　underground　crude　oil　storage　cavern.　Grouting　effect　can　also　be　conveniently　investigated　by　the　unified　pipe　network　system.　Results　show　that　the　proposed　method　is　robust　in　seepage　analysis　for　both　fractured　and　porous　rock　masses.　(C)　2016　Elsevier　Ltd.　All　rights　reserved.