Longueur de la tige de forage : pourquoi plus long n'est pas toujours mieux
Rock Drill Rod Length Selection: Why Longer Is Not Always Better
In tunnel development and underground mining, drill rod length has a direct effect on drilling efficiency, equipment mobility, and the quality of the drilling cycle. A longer rod can increase single-pass drilling depth, but it is not automatically the best choice for every job.
The right selection depends on the excavation profile, designed hole depth, available operating space, drilling rig configuration, and production plan.
Select for Fit, Not Maximum Length
A common assumption is that longer drill rods always mean deeper holes and higher productivity. In reality, drill rod selection is about matching the rod to the working conditions.
An oversized rod can limit boom movement, restrict machine positioning, complicate hole changes, and reduce operator working space. These issues may slow the drilling cycle instead of improving it.
How Drill Rod Length Affects the Drilling Cycle
In drill-and-blast operations, the advance achieved in each cycle is closely linked to hole depth. A longer rod can reduce the frequency of rod coupling and uncoupling, allowing a drilling jumbo to complete deeper holes with fewer interruptions.
Where site conditions support it, fewer rod changes can improve process continuity, reduce auxiliary time, and lower manual handling requirements. However, these benefits only apply when the equipment can operate safely and effectively within the available space.
Typical Use Cases for 2.5 m and 3 m Drill Rods
2.5 m Drill Rods: Flexible Choice for Confined Areas
A 2.5 m rod is generally better suited to smaller tunnel sections, restricted sites, and work areas where equipment movement is limited. Its shorter length supports more flexible boom adjustment, multi-hole positioning, and angle changes.
This makes it useful where maneuverability is more important than maximum single-pass drilling depth.
3 m Drill Rods: Higher Efficiency in Open Working Areas
A 3 m rod is better suited to larger excavation profiles with adequate working room. The longer drilling reach can reduce the number of rod changes and simplify the drilling process, supporting a higher advance per drilling cycle.
It is most appropriate where project targets require efficient advance and the drilling rig has sufficient clearance to operate without restriction.
Avoid Oversized Drill Rods in Small Tunnel Sections
In small tunnel sections, efficiency problems are often caused by limited operating space rather than insufficient drilling depth. Using an overly long drill rod can make it difficult to position the boom, turn or relocate the rig, switch between holes, and maintain a practical working area for the operator.
A balanced selection may involve choosing between 2.5 m and 3 m rods according to the excavation width, height, planned hole depth, and rig operating envelope.
The final configuration should always be confirmed by the equipment manufacturer, qualified site engineers, and the approved drilling plan.
