Microtunneling A to Z
Microtunneling is a precise, trenchless method, but the field has its own language! As an operator with over 7 years in microtunnelling (including 2 years hands-on with MARS 450/400), I've compiled this A to Z guide from real site experience. This is not textbook stuff—it's what actually matters on the job. Use this as your quick reference when you're in the pit or briefing the team. Let's go letter by letter! A – Alignment & Annular Space Alignment : The straight-line path from launch to reception shaft. Use laser theodolite or target system to keep deviation under 50mm (MARS machines are forgiving, but over 100mm = big trouble). Annular Space : The gap between pipe OD and bored hole. Keep it 20-50mm for lubricant flow—too tight = friction spike, too wide = settlement risk. B – Bentonite / Borehole Stability Bentonite slurry stabilizes the borehole walls. Mix properly (usually 5-8% concentration). Warning: Poor mixing = cave-in at launch! C – Cutterhead & Cutt...
