Abstract: Firstly, the momentum equilibrium equation, the continuity equation for water and the elastoplastic matrix are established. Secondly, by using the Galerkin method all the governing equations are discretized in the space domain and in the time domain respectively; then a two dimensional FEM code for coupling hydro-mechanical elastoplastic analysis of saturated-unsaturated porous medium is developed tentatively. Through a numerical computation for the assumed coupled hydro-mechanical problem of prestressed bolting support in a saturated- unsaturated soil body located a seepage field, it is shown that under the saturated-unsaturated condition , the prestressed bolting decreases mainly the plastic zone in the soil body; its restraint action for displacements changes according to the soil positions; and its influence on sepage field is not obvious.

Key words: saturated-unsaturated geologic medium, hydro-mechanical coupling, 2D FEM code, bolting support