This paper describes several sources of external dilution affecting the
stope walls during underground sub-level and bench stoping. Factors
which control ground behaviour such as the geometry of the openings, the
influence of geological discontinuities, stress re-distribution and blasting
practices are discussed. Crown stope instability due to stress
concentrations induced by changes in the excavation geometry, is
discussed and the most efficient ways to sequence blasting within a stope
are analysed. Effects of undercutting by blasting, blast damage in the near
field and cut-off slot blast designs are analysed. The influence of dynamic
loading on the exposed walls as well as the practice of blasting fill passes
within stope crowns are discussed.