Every blast splits its energy two ways. Applied energy, the shock and heave that break and move rock, does the work. Lost energy escapes as air over-pressure, ground vibration and excess fines. Stemming decides much of that split.
Scaled Depth of Burial in brief
Scaled Depth of Burial (SDOB) measures how well a charge is confined. It relates stemming height to the explosive column, scaled to a reference of 10 hole diameters. When SDOB is controlled, rock breakage improves and environmental impact drops.
Where stemming fails
- Premature venting through the collar before the burden moves
- Stemming ejection that throws material and creates flyrock
- Inconsistent stemming heights from hole to hole
- Water and emulsion mixing with stemming material at the collar
What a stemming plug changes
A stemming plug such as Varistem® sits above the charge and holds the stemming column in place. Product data shows it doubles stemming time to movement and halves stemming ejection velocity.
- Better fragmentation in the cap-rock zone
- Less flyrock and air blast
- Consistent stemming heights regardless of hole depth or loading
- Room to widen patterns, reducing drilling and explosive cost
Protect the hole before you charge it
Confinement starts before loading. Collar savers keep cuttings, water and fauna out of drilled holes, and liners stop water desensitising the product in wet or fractured ground.
