08/06/2026
Common Process & Operational Issues with Raise Boring Machines (RBM) – And How to Mitigate Them
When it comes to raise boring operations, process-related problems are often the most damaging and can lead to project failure. Here are six critical issues to watch for – plus key prevention tips.
1. Pilot Hole Deviation
One of the toughest challenges. Uneven ground and drill string deformation are the main causes.
✅ Prevention: Ensure the rig is perfectly level and stable from the start. Use a gyro inclinometer for real-time monitoring and active correction. Current tech can keep vertical deviation within 0.8%.
2. Stuck Drilling / Reaming
Common during pilot or reaming stages, often due to hole collapse or falling rock blocks.
✅ Response: Try “down-pressure + forward rotation”. Reduce thrust when entering fractured zones. Only experienced personnel should handle stuck drills.
3. Hole Collapse & Wall Instability
Happens in fault zones, broken formations, or when flushing pressure is improperly set.
✅ Prevention: Use high-quality mud for wall support. Lower bit pressure when drilling through broken ground.
4. Drill Pipe / Tool Breakage
Caused by long-term cyclic stress, severe wear, or bending.
✅ Prevention: Rigorously inspect all pipes. Immediately remove any with excessive wear or signs of bending.
5. Severe Reamer Head & Disc Cutter Damage
High-speed drilling in extremely hard rock or improper parameters (thrust, RPM) leads to abnormal wear or tooth breakage.
✅ Prevention: Adjust drilling parameters based on rock conditions. Avoid aggressive over-speeding.
6. Shaft Wall Stability Risks
In deep high-stress zones or soft rock, wall peeling, squeezing, or deformation can damage the entire shaft structure.
✅ Prevention: Conduct thorough geotechnical analysis beforehand. Adjust support measures and advance rate accordingly.
🎯 Proactive monitoring, proper parameter control, and regular equipment inspection are the keys to avoiding these costly failures.