ABSTRACT
Various parameters affect the behaviour of crush pillars in intermediate depth platinum mines. The final crush pillar dimension and overall mining layout is influenced by the original design methodology, mining discipline and the effect of unexpected geological losses. The combination of these factors can prevent the pillars from crushing and achieving the desired post-peak residual state. This may result in unpredictable pillar behaviour and damaging seismicity.
Effective crush pillar design will require the pillars being crushed while being formed at the mining face. A stability analysis has been recommended in the past as a method to design yield pillars at moderate mining depths. The methodology assumes that stable pillar crushing will occur if the local rock mass stiffness is greater than the post-failure stiffness of the crush pillar at the specific pillar location. This paper explores this design methodology and some preliminary numerical results are discussed.
