Collapse　mechanism　for　the　tunnel　or　underground　cavern　is　important　for　the　support　system　design.　This　paper　investigates　the　progressive　failure　phenomenon　of　the　shallow　tunnel　roof　under　the　condition　of　plane　strain　by　virtue　of　the　functional　catastrophe　theory.　Firstly,　considering　the　plastic　strain　energy　as　an　index　for　the　state　of　the　studied　system,　the　analytical　solutions　for　the　profile　curves　of　the　collapsing　blocks　from　the　shallow　tunnel　roof　including　the　＇underground＇　collapse　and　＇spalling＇　collapse　are　deduced　on　the　basis　of　the　nonlinear　power-law　failure　criterion.　Moreover,　the　criterions　are　derived　to　estimate　whether　the　progressive　failure　phenomena　including　the　＇underground＇　collapses　and　＇spalling＇　collapses　for　shallow　tunnel　roof　would　occurr　or　not.　Then,　the　analytical　prediction　obtained　from　this　paper　for　the　shallow　tunnels　is　compared　with　the　existing　analytical　prediction　for　the　deep　tunnels.　Finally,　the　comparisons　of　the　results　between　analytical　prediction　obtained　from　this　paper　and　two　existing　model　tests　are　conducted　to　demonstrate　the　validity　of　the　proposed　analytical　methodology.