For　an　analysis　of　the　stability　of　an　underground　excavation　in　two　dimensional　space,　the　convergence-confinement　tunnel　design　process　is　usually　applied　to　investigate　the　interaction　of　support　and　ground　of　the　excavation.　In　order　to　achieve　the　design　process,　a　coefficient　of　stress　release　is　defined.　The　stress　release　process　is　realized　using　a　numerical　software　UDEC,　which　is　validated　by　the　closed-form　solution　of　a　circular　tunnel.　The　stability　of　a　cavern　in　rockmass　is　analyzed　based　on　the　convergence-confinement　method　using　UDEC.　The　displacement　around　the　cavern　is　investigated.　The　numerical　results　show　that　the　magnitude　of　displacement　depends　on　the　stress　release,　i.e.,　the　installation　of　support.