The　critical　suction　pressure　will　lead　to　the　difference　in　equivalent　overburdens　at　the　skirt-tip　level　between　outside　and　inside　the　caisson　exceeds　N(c)(r)s(u)　(N-c(r)　is　the　local　reverse　bearing　capacity　factor,　and　s(u)　is　the　undrained　shear　strength　of　clay　at　the　skirt-tip),　which　may　induce　the　local　reverse　bearing　capacity　failure　of　soil　near　the　skirt-tip.　As　a　result,　soil　flows　into　the　caisson　cavity,　making　soil　plug　heave　higher　that　prevents　the　caisson　from　penetrating　to　its　desired　depth.　This　paper　is　the　first　to　apply　the　limit　analysis　to　obtain　a　theoretical　study　on　determining　the　critical　suction　pressure　based　on　the　local　reverse　failure　mechanism　near　the　skirt-tip.　This　study　is　also　the　first　to　consider　the　effects　of　adhesion　factors　along　the　inside　(alpha(i))　and　outside　(alpha(o))　of　the　skirt　wall　on　the　local　reverse　bearing　capacity　failure　mechanism　reflecting　that　N-c(r)　includes　alpha(i)　and　alpha(o).　It　is　shown　that　N-c(r)　ranges　from　5.14　(alpha(i)=alpha(o)=0)　to　8.28　(alpha(i)=alpha(o)=1),　and　the　values　of　alpha(o)　and　alpha(i)　are　all　between　0　and　1.　In　addition,　the　critical　penetration　depth　can　be　determined　under　the　condition　that　the　critical　suction　pressure　equals　the　required　suction　pressure.　And,　the　proposed　method　of　calculating　the　critical　penetration　depth　is　testified　to　be　in　good　agreement　with　the　experimental　results.