Modelling of stope and gully support systems.

Rock related accidents most frequently take place at stope faces and in gullies near the face. A review is presented of the challenges of modelling deep level excavations. Recent efforts by CSIR Miningtek to use numerical models to evaluate various aspects of stope and gully support systems are described. Both FLAC, an explicit finite difference code and UDEC, a distinct element code, also based on a finite difference method, were used to: model the influence of backfill stiffness and distance to the face on hangingwall stability; investigate the effect on the stability of the stope hangingwall of the spacing of support units, support unit force and areal coverage of support; and to assess the relationship between gully pack force and gully sidewall damage. Good modelling results can be obtained where mechanisms influencing global rock mass behaviour and stability are active, but modelling of local mechanisms associated with the local stability of blocky hangingwalls still requires development.
Rock related accidents most frequently take place at stope faces and in gullies near the face. A review is presented of the challenges of modelling deep level excavations. Recent efforts by CSIR Miningtek to use numerical models to evaluate various aspects of stope and gully support systems are described. Both FLAC, an explicit finite difference code and UDEC, a distinct element code, also based on a finite difference method, were used to: model the influence of backfill stiffness and distance to the face on hangingwall stability; investigate the effect on the stability of the stope hangingwall of the spacing of support units, support unit force and areal coverage of support; and to assess the relationship between gully pack force and gully sidewall damage. Good modelling results can be obtained where mechanisms influencing global rock mass behaviour and stability are active, but modelling of local mechanisms associated with the local stability of blocky hangingwalls still requires development.