Abstract: According to the breakage of shaft,the empirical and the therory formula was put forward and studied the change of plastic zone when the is zero in water-rich strata and proposed the reinforcement.Through the local practice,the settlement of vault reduced to 7.9mm,the convergence of sides reduced to 5mm,the floor heave reduced to 2mm and the plastic zone is 1.8mm.The reinforcement can ensure the safty of the construction of shaft

Key words: warter-rich, plastic zone, failure mechanism, supporting measure, numerical simulation