In the current conditions of mines exploited by caving methods, pre-conditioning by hydraulic fracturing has proven to have positive impacts such as the decrease in the block’s size related to the primary fragmentation. An essential part of the pre-conditioning design is the estimation of the hydraulic fractures length. On the other hand, the energy dissipated by the viscous flow imide the fracture modifies the propagation characteristics of these fractures, making difficult the use of standard methods of fracture mechanics in numerical modelling. For this reason, for plain-strain and axisymmetric cases we propose a numerical resolution strategy, which can be used for any set of hydraulic fracturing parameters. These criteria are based on the pressure and opening values at the inlet, and additionally on their length (or radius). Furthermore, this last characteristic, allow us to modify the propagation criteria in order to generate diagnostic tools for the estimation of fractures dimensions in the field.