Modelling Drainage Systems in Hydraulic Fills
An important aspect of designing hydraulic backfill pours is determining the ratio between the filling and drainage times. This paper will present a modelling methodology that can be used to calculate this ratio for a given stope size. The model determines the amount of water that leaves the filling stope using the fluid flow module of Itasca’s Flac3D code. This software also allows more complicated behaviour to be modeled, such as the time dependent drainage of cemented hydraulic fill or the use of drains within the fill mass.
The paper will summarize the theory behind the modelling methodology and will then present the design criteria and assumptions used to build the model. It will then present an analysis of the filling procedure for a typical stope size. This analysis will compare different filling strategies such as a continuous pour versus either a pre-determined staged pour or a model-determined staged pour. The inclusion of drains will then be explored to show how the use of drains can benefit the pour design. Finally, the authors will comment on how the different drainage systems can impact the behaviour of the backfill and on the stope’s barricade fence.