Tunnel Construction Sequence Involving Robotic Wet Shotcrete and Rock Drilling Machines
After the application of wet shotcrete using a robotic shotcrete spraying system, the rock drilling machine enters the tunnel to carry out the next phase of excavation or support installation.
✅ Sequence Description
Initial Excavation (if applicable)
The tunnel face is first excavated using a drill-and-blast method or TBM.
Robotic Wet Shotcrete Application
A robotic wet shotcrete machine is deployed to spray concrete on the freshly excavated tunnel surface.
Purpose: Provide immediate support, prevent loose rock from falling, and control groundwater ingress.
Entry of Rock Drilling Machine
After the sprayed concrete has reached sufficient early strength (typically within minutes to hours), the rock drilling machine (jumbo) is moved into position.
Operations:
Drilling blast holes for the next round of excavation (in drill-and-blast tunneling)
Drilling holes for rock bolts, anchors, or probe holes
Instrumentation installation (e.g., extensometers or piezometers)
⚠️ Key Considerations
Shotcrete Setting Time: Ensure the sprayed concrete has achieved sufficient initial set before allowing equipment to move over it.
Ventilation: Proper ventilation must be maintained due to dust and fumes from both shotcreting and drilling.
Safety Coordination: A proper time gap and inspection are required between spraying and machine entry to avoid accidents or premature loading on fresh shotcrete.
🔄 Repeatable Cycle in Drill-and-Blast Tunneling
This sequence (Excavation → Shotcrete → Drilling → Blasting → Mucking → Shotcrete again) is repeated cyclically in the advance of the tunnel.
If you'd like, I can turn this into a method statement, sequence diagram, or construction report section-just let me know your use case.
