3D, Mine scale, Discontinuum, Hydromechanical Coupled, LARGE Open Pit Simulation

Water pressure impacts on stability and rock damage affects flow, but in the past, coupled hydromechanical simulation was uncommon. Now, 3-dimensional, fully or partially coupled hydromechanical simulation for entire mines is possible. The models include large numbers of explicit  discontinuities and are displacement realistic. Some of the largest open pits in the world are now employing Beck Engineering’s 3D HMC FE Models.

How does it work?

The standard, conventional equations governing fluid flow and pore water pressure can be solved simultaneously with the equations for deformation and damage inside 3D mine scale discontinuum models. A relationship between permeability and rock damage is also defined and acts as a constraint on the solution. In a fully coupled simulation the deformation part and the hydrology part are not changed from normal best practice; they are just coupled so that the interactions are accounted for at every time step.

Discontinuities can be handled in a number of ways consistent with normal stress-deformation and hydrological modelling—they can be included explicitly or implicitly and the different hydrogeological domains can be mapped with the geological domains, or as separate volumes. All else being equal, the results for 3d fully coupled modelling are more realistic and the models require fewer assumptions, resulting in lower uncertainty.

Fig.1: Examples of displacements for a 3d mine scale hydromechanical coupled lop model

Fig.3: Examples of poew water pressure and pore fluid velocity for a 3d mine scale hydromechanical coupled lop model

How is it used?

Fully and partially coupled 3-dimensional hydromechanical modelling should become standard practice for pit slope simulations – there are no technical hurdles to using the technology to improve model reliability today. The methods capture an important aspect of pit slope behaviour that isn’t often handled well. Any large slope where pore water pressure is a factor in stability should consider the advantages of undertaking hydromechanical coupled analysis.

Contact dbeck@beckengineering.com.au for more details