Constellation, le dépôt institutionnel de l'Université du Québec à Chicoutimi

Résumé

The surface area of the fractures at the wall of a tunnel is used to develop a representative index, as inflow index, for the prediction and the classification of the inflow rate to a tunnel that is excavated in a fractured rock mass. For this purpose, an analytical model has been developed for the calculation of the inflow index based on geometrical characteristics of the discontinuities and of the tunnel. The result of the analytical model is validated by numerical simulations using 3DEC version 7.0 software. Furthermore, the simulation results demonstrate the capacity of the inflow index to predict the inflow rate to the tunnel. At a constant value of the water head, the inflow rate to the tunnel increases with increasing value of the inflow index. In addition, the inflow rate could be classified to various levels, based on the values of inflow index. The study has identified that the hydraulic aperture, joint spacing, tunnel radius and the angle between tunnel and normal to joint sets have the most important impacts on the inflow index and among them, the effect of hydraulic aperture is the most important one.