ABSTRACT
The relevancy of the flow rate into the tunnel to the block volume and block surface area has been investigated. A set of numerical simulations with Itasca 3DEC version 7.0 is performed in order to define each parameter’s impact on the inflow rate to the tunnel. The numerical model consists of a fractured rock mass that includes three joint sets with a fixed value of the hydraulic aperture and level of water table. The tunnel has a circular cross-section and the fluid flows only through the area between the fracture planes. Different values of the block volume and block surface are achieved by variation of the orientation and spacing of the joint sets. The block volume and surface are calculated both by analytical and numerical methods. For this, a new analytical model is developed for calculation of the block surface area. Based on the results of the numerical simulations of the inflow rate, it is deduced that the inflow rate increases by decrease of the block volume and block surface. Among them, the relationship between the inflow rate and block volume is more relevant than block surface area. In addition, it is proved that the common analytical method for calculation of the block volume needs to be revised for obtaining more reliable results.
