The coupled hydro-mechanical processes in fractured rock during tunnel excavation are analyzed

using the stochastic continuum model that represents the spacial variability in hydraulic properties of fractured rock mass. The stochastic permeability fields are generated with the sequential indicator simulation

which is a non-parametric geostatistical technique and allows the input of the permeability probability distribution of arbitrary shape. The resulted permeability fields are then mapped onto the 3D finite element grids for the coupled hydro-mechanical analysis. A joint material model that can represents the weaken planes with specific orientations is used for the mechanical calculation in the study. The results show that the stochastic continuum model can predict the inflow rate into the tunnel; and the natural

spacial variability in hydraulic properties plays an important role in the coupled hydro-mechanical processes of the fractured rock mass. It is also found that the pore pressure will rise quickly before the water has a chance to move and equilibrate at the beginning of every excavation stage. This transient coupled hydro-mechanical effect may cause local failures in rock.