This　paper　investigated　the　undrained　responses　for　deep　circular　tunnels　with　reinforcement　in　saturated　ground　analytically.　An　idealized　model　of　an　axisymmetric　tunnel　with　an　initial　hydrostatic　stress　field　was　proposed.　Plane-strain　analysis　was　performed　to　obtain　the　ground　reaction　curves　by　gradually　decreasing　the　internal　support　pressure　from　the　initial　stress　to　zero　after　tunnel＂　excavation.　The　reinforced　ground　by　full　face　grouting　was　assumed　as　an　equivalent　circular　region　to　consider　the　reinforcement　effect.　Both　of　the　natural　ground　and　the　reinforced　ground　were　assumed　as　the　elastic-perfectly　plastic　materials　satisfying　the　Mohr-Coulomb　yield　criterion.　The　proposed　model　was　used　to　estimate　the　efficiency　of　the　reinforcement　parameters　for　a　deep　underwater　tunnel.　The　analytical　results　were　validated　by　the　numerical　results.　Results　show　that　as　the　decrease　of　internal　support　pressure,　the　plastic　zone　may　firstly　appear　not　only　in　the　reinforced　ground　or　in　the　natural　ground,　but　also　appear　in　the　two　zones　simultaneously.　Six　forms　of　different　plastic　zone　distributions　were　categorized.　The　ground　reaction　curve　for　each　form　was　analyzed　and　8　critical　support　pressures　were　obtained　in　the　unified　theoretical　framework　for　the　specific　boundary　conditions.　The　present　model　has　advantages　in　undrained　analysis　of　ground　reaction　curves　for　deep　tunnels　in　saturated　ground　considering　the　effects　of　ground　reinforcement　compared　with　the　classical　model.