Sensitivity Analysis of Effective Parameters on the Permeability of Rock Mass Around a Tunnel Available to Purchase

Permeability of rock mass is the most important parameter for computing tunnel inflow. In jointed hard rocks, groundwater mainly flows through discontinuities. Geometrical characterisations of joint set such as orientation, trace length, spacing, and aperturecontrol the permeabilityof the rock mass. In this study a new method is proposed for estimating of the equivalent permeability of rock mass around a tunnel based on intersection probability of rock joint with tunnel walls. This method considers finite joints and interconnectivity of jointed network. Effects of geometrical characterisations of joint sets on the permeability of rock mass are studied using sensitivity analysis of input parameters inthe new proposed model. This analysis demonstrates that the permeability increase with increment of joint length and joint inclination. The increment of joint spacing decreases the permeability. Furthermore, in this new method anisotropy of permeability of the whole rock mass can be determined by computing the permeability in different tunnel trends. Since there is inherent uncertainty in rock joint properties, this procedureincreases understanding oneffective parameters and helps to optimise required design measures for preventing tunnel inundation.